diff options
| -rw-r--r-- | README.md | 91 | ||||
| -rw-r--r-- | actions/config.go | 4 | ||||
| -rw-r--r-- | actions/context.go | 19 | ||||
| -rw-r--r-- | actions/policy.go | 89 | ||||
| -rw-r--r-- | actions/protector.go | 6 | ||||
| -rw-r--r-- | cmd/fscrypt/commands.go | 195 | ||||
| -rw-r--r-- | cmd/fscrypt/errors.go | 24 | ||||
| -rw-r--r-- | cmd/fscrypt/flags.go | 43 | ||||
| -rw-r--r-- | cmd/fscrypt/fscrypt.go | 2 | ||||
| -rw-r--r-- | cmd/fscrypt/protector.go | 6 | ||||
| -rw-r--r-- | cmd/fscrypt/status.go | 18 | ||||
| -rw-r--r-- | crypto/crypto.go | 43 | ||||
| -rw-r--r-- | crypto/crypto_test.go | 81 | ||||
| -rw-r--r-- | crypto/key.go | 56 | ||||
| -rw-r--r-- | keyring/fs_keyring.go | 318 | ||||
| -rw-r--r-- | keyring/keyring.go | 155 | ||||
| -rw-r--r-- | keyring/keyring_test.go | 350 | ||||
| -rw-r--r-- | keyring/user_keyring.go (renamed from security/keyring.go) | 90 | ||||
| -rw-r--r-- | metadata/checks.go | 35 | ||||
| -rw-r--r-- | metadata/config_test.go | 44 | ||||
| -rw-r--r-- | metadata/constants.go | 18 | ||||
| -rw-r--r-- | metadata/metadata.pb.go | 142 | ||||
| -rw-r--r-- | metadata/metadata.proto | 3 | ||||
| -rw-r--r-- | metadata/policy.go | 170 | ||||
| -rw-r--r-- | metadata/policy_test.go | 63 | ||||
| -rw-r--r-- | pam/pam.go | 19 | ||||
| -rw-r--r-- | pam_fscrypt/pam_fscrypt.go | 86 | ||||
| -rw-r--r-- | security/privileges.go | 8 |
28 files changed, 1795 insertions, 383 deletions
@@ -91,7 +91,8 @@ Concretely, fscrypt contains the following functionality: * `fscrypt setup MOUNTPOINT` - Gets a filesystem ready for use with fscrypt * `fscrypt encrypt DIRECTORY` - Encrypts an empty directory * `fscrypt unlock DIRECTORY` - Unlocks an encrypted directory -* `fscrypt purge MOUNTPOINT` - Removes keys for a filesystem before unmounting +* `fscrypt lock DIRECTORY` - Locks an encrypted directory +* `fscrypt purge MOUNTPOINT` - Locks all encrypted directories on a filesystem * `fscrypt status [PATH]` - Gets detailed info about filesystems or paths * `fscrypt metadata` - Manages policies or protectors directly @@ -193,8 +194,10 @@ that looks like the following: "options": { "padding": "32", "contents": "AES_256_XTS", - "filenames": "AES_256_CTS" - } + "filenames": "AES_256_CTS", + "policy_version": "1" + }, + "use_fs_keyring_for_v1_policies": false } ``` @@ -236,6 +239,25 @@ The fields are: documentation](https://www.kernel.org/doc/html/latest/filesystems/fscrypt.html#encryption-modes-and-usage) for more details about the supported algorithms. + * "policy\_version" is the version of encryption policy to use. + The choices are "1" and "2". Directories created with policy + version "2" are only usable on kernel v5.4 or later, but are + preferable to version "1" if you don't mind this restriction. + +* "use\_fs\_keyring\_for\_v1\_policies" specifies whether to add keys + for v1 encryption policies to the filesystem keyring, rather than to + user keyrings. This can solve [issues with processes being unable + to access encrypted files](#cant-log-in-with-ssh-even-when-users-encrypted-home-directory-is-unlocked). + However, it requires kernel v5.4 or later, and it makes unlocking + and locking encrypted directories require root. + + The purpose of this setting is to allow people to take advantage of + some of the improvements in Linux v5.4 on encrypted directories that + are also compatible with older kernels. If you don't need + compatibility with older kernels, it's better to not use this + setting and instead (re-)create your encrypted directories with + `"policy_version": "2"`. + ### Setting up the PAM module Note that to make use of the installed PAM module, your @@ -278,8 +300,9 @@ after `pam_unix.so` in `/etc/pam.d/common-session` or similar. The `lock_policies` option locks the directories protected with the user's login passphrase when the last session ends. The `drop_caches` option tells fscrypt to clear the filesystem caches when the last session closes, ensuring all the -locked data is inaccessible. All the types also support the `debug` option which -prints additional debug information to the syslog. +locked data is inaccessible; this only needed for v1 encryption policies. +All the types also support the `debug` option which prints additional +debug information to the syslog. ## Note about stability @@ -360,24 +383,23 @@ POLICY UNLOCKED PROTECTORS "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: Yes Protected with 1 protector: PROTECTOR LINKED DESCRIPTION 7626382168311a9d No custom protector "Super Secret" -# Purging a filesystem locks all the files. ->>>>> sudo fscrypt purge /mnt/disk --user=$USER -WARNING: Encrypted data on this filesystem will be inaccessible until unlocked again!! -Purge all policy keys from "/mnt/disk" and drop global inode cache? [y/N] y -Policies purged for "/mnt/disk". - +# Lock the directory. 'sudo' and the '--user' argument are only +# required if the directory uses a v1 encryption policy. +>>>>> sudo fscrypt lock /mnt/disk/dir1 --user=$USER +Encrypted data removed from filesystem cache. +"/mnt/disk/dir1" is now locked. >>>>> fscrypt status /mnt/disk/dir1 "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: No Protected with 1 protector: @@ -398,7 +420,7 @@ Enter custom passphrase for protector "Super Secret": "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: Yes Protected with 1 protector: @@ -410,7 +432,7 @@ Hello World #### Quiet Version ```bash ->>>>> sudo fscrypt purge /mnt/disk --user=$USER --quiet --force +>>>>> sudo fscrypt lock /mnt/disk/dir1 --quiet --user=$USER >>>>> echo "hunter2" | fscrypt unlock /mnt/disk/dir1 --quiet ``` @@ -434,7 +456,7 @@ Enter login passphrase for joerichey: "/mnt/disk/dir2" is encrypted with fscrypt. Policy: fe1c92009abc1cff -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: Yes Protected with 1 protector: @@ -470,7 +492,7 @@ PROTECTOR LINKED DESCRIPTION "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: Yes Protected with 1 protector: @@ -566,7 +588,7 @@ fe1c92009abc1cff No 6891f0a901f0065e "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: No Protected with 1 protector: @@ -582,7 +604,7 @@ Protector 2c75f519b9c9959d now protecting policy 16382f282d7b29ee. "/mnt/disk/dir1" is encrypted with fscrypt. Policy: 16382f282d7b29ee -Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS +Options: padding:32 contents:AES_256_XTS filenames:AES_256_CTS policy_version:1 Unlocked: No Protected with 2 protectors: @@ -715,6 +737,37 @@ shred -u file However, `shred` isn't guaranteed to be effective on all filesystems and storage devices. +#### Can't log in with ssh even when user's encrypted home directory is unlocked + +This is caused by a limitation in the original design of Linux +filesystem encryption which made it difficult to ensure that all +processes can access unlocked encrypted files. This issue can also +manifest in other ways such as Docker containers being unable to +access encrypted files, or NetworkManager being unable to access +certificates if they are located in an encrypted directory. + +If you are using kernel v5.4 or later, you can fix this by setting the +following in `/etc/fscrypt.conf`: + + "use_fs_keyring_for_v1_policies": true + +However, this makes manually unlocking and locking encrypted +directories start to require root. (The PAM module will still work.) +E.g., you'll need to run `sudo fscrypt unlock`, not `fscrypt unlock`. + +Alternatively, you can upgrade your encrypted directories to use v2 +encryption policies by setting the following in the "options" section +of `/etc/fscrypt.conf`: + + "policy_version": "2" + +... and then for each of your encrypted directories, using `fscrypt +encrypt` to encrypt a new empty directory, copying your files into it, +and replacing the original directory with it. This will fix the key +access problems, while also keeping `fscrypt unlock` and `fscrypt +lock` usable by non-root users. This is the recommended solution if +you don't need to access your files on kernels older than v5.4. + ## Legal Copyright 2017 Google Inc. under the diff --git a/actions/config.go b/actions/config.go index 7fdaf5b..6b019df 100644 --- a/actions/config.go +++ b/actions/config.go @@ -133,6 +133,10 @@ func getConfig() (*metadata.Config, error) { config.Options.Filenames = metadata.DefaultOptions.Filenames log.Printf("Falling back to filenames mode of %q", config.Options.Filenames) } + if config.Options.PolicyVersion == 0 { + config.Options.PolicyVersion = metadata.DefaultOptions.PolicyVersion + log.Printf("Falling back to policy version of %d", config.Options.PolicyVersion) + } if err := config.CheckValidity(); err != nil { return nil, errors.Wrap(ErrBadConfigFile, err.Error()) diff --git a/actions/context.go b/actions/context.go index 5a56789..f07f225 100644 --- a/actions/context.go +++ b/actions/context.go @@ -37,6 +37,7 @@ import ( "github.com/pkg/errors" "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/metadata" "github.com/google/fscrypt/util" ) @@ -57,10 +58,13 @@ type Context struct { // modified after being loaded to customise parameters. Config *metadata.Config // Mount is the filesystem relative to which all Protectors and Policies - // are added, edited, removed, and applied. + // are added, edited, removed, and applied, and to which policies using + // the filesystem keyring are provisioned. Mount *filesystem.Mount - // TargetUser is the user for which protectors are created and to whose - // keyring policies are provisioned. + // TargetUser is the user for whom protectors are created, and to whose + // keyring policies using the user keyring are provisioned. It's also + // the user for whom the keys are claimed in the filesystem keyring when + // v2 policies are provisioned. TargetUser *user.User } @@ -145,6 +149,15 @@ func (ctx *Context) getService() string { return unix.FSCRYPT_KEY_DESC_PREFIX } +func (ctx *Context) getKeyringOptions() *keyring.Options { + return &keyring.Options{ + Mount: ctx.Mount, + User: ctx.TargetUser, + Service: ctx.getService(), + UseFsKeyringForV1Policies: ctx.Config.GetUseFsKeyringForV1Policies(), + } +} + // getProtectorOption returns the ProtectorOption for the protector on the // context's mountpoint with the specified descriptor. func (ctx *Context) getProtectorOption(protectorDescriptor string) *ProtectorOption { diff --git a/actions/policy.go b/actions/policy.go index 875a01f..41e108e 100644 --- a/actions/policy.go +++ b/actions/policy.go @@ -28,8 +28,8 @@ import ( "github.com/google/fscrypt/crypto" "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/metadata" - "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" ) @@ -44,8 +44,8 @@ var ( ) // PurgeAllPolicies removes all policy keys on the filesystem from the kernel -// keyring. In order for this removal to have an effect, the filesystem should -// also be unmounted. +// keyring. In order for this to fully take effect, the filesystem may also need +// to be unmounted or caches dropped. func PurgeAllPolicies(ctx *Context) error { if err := ctx.checkContext(); err != nil { return err @@ -56,12 +56,16 @@ func PurgeAllPolicies(ctx *Context) error { } for _, policyDescriptor := range policies { - service := ctx.getService() - err = security.RemoveKey(service+policyDescriptor, ctx.TargetUser) - + err = keyring.RemoveEncryptionKey(policyDescriptor, ctx.getKeyringOptions(), false) switch errors.Cause(err) { - case nil, security.ErrKeySearch: + case nil, keyring.ErrKeyNotPresent: // We don't care if the key has already been removed + case keyring.ErrKeyFilesOpen: + log.Printf("Key for policy %s couldn't be fully removed because some files are still in-use", + policyDescriptor) + case keyring.ErrKeyAddedByOtherUsers: + log.Printf("Key for policy %s couldn't be fully removed because other user(s) have added it too", + policyDescriptor) default: return err } @@ -94,11 +98,17 @@ func CreatePolicy(ctx *Context, protector *Protector) (*Policy, error) { return nil, err } + keyDescriptor, err := crypto.ComputeKeyDescriptor(key, ctx.Config.Options.PolicyVersion) + if err != nil { + key.Wipe() + return nil, err + } + policy := &Policy{ Context: ctx, data: &metadata.PolicyData{ Options: ctx.Config.Options, - KeyDescriptor: crypto.ComputeDescriptor(key), + KeyDescriptor: keyDescriptor, }, key: key, created: true, @@ -188,17 +198,16 @@ func (policy *Policy) Descriptor() string { return policy.data.KeyDescriptor } -// Description returns the description that will be used when the key for this -// Policy is inserted into the keyring -func (policy *Policy) Description() string { - return policy.Context.getService() + policy.Descriptor() -} - // Options returns the encryption options of this policy. func (policy *Policy) Options() *metadata.EncryptionOptions { return policy.data.Options } +// Version returns the version of this policy. +func (policy *Policy) Version() int64 { + return policy.data.Options.PolicyVersion +} + // Destroy removes a policy from the filesystem. The internal key should still // be wiped with Lock(). func (policy *Policy) Destroy() error { @@ -374,11 +383,24 @@ func (policy *Policy) Apply(path string) error { return metadata.SetPolicy(path, policy.data) } -// IsProvisioned returns a boolean indicating if the policy has its key in the -// keyring, meaning files and directories using this policy are accessible. -func (policy *Policy) IsProvisioned() bool { - _, err := security.FindKey(policy.Description(), policy.Context.TargetUser) - return err == nil +// GetProvisioningStatus returns the status of this policy's key in the keyring. +func (policy *Policy) GetProvisioningStatus() keyring.KeyStatus { + status, _ := keyring.GetEncryptionKeyStatus(policy.Descriptor(), + policy.Context.getKeyringOptions()) + return status +} + +// IsProvisionedByTargetUser returns true if the policy's key is present in the +// target kernel keyring, but not if that keyring is a filesystem keyring and +// the key only been added by users other than Context.TargetUser. +func (policy *Policy) IsProvisionedByTargetUser() bool { + return policy.GetProvisioningStatus() == keyring.KeyPresent +} + +// IsFullyDeprovisioned returns true if the policy has been fully deprovisioned, +// including by all users and with all files protected by it having been closed. +func (policy *Policy) IsFullyDeprovisioned() bool { + return policy.GetProvisioningStatus() == keyring.KeyAbsent } // Provision inserts the Policy key into the kernel keyring. This allows reading @@ -387,13 +409,34 @@ func (policy *Policy) Provision() error { if policy.key == nil { return ErrLocked } - return crypto.InsertPolicyKey(policy.key, policy.Description(), policy.Context.TargetUser) + return keyring.AddEncryptionKey(policy.key, policy.Descriptor(), + policy.Context.getKeyringOptions()) } // Deprovision removes the Policy key from the kernel keyring. This prevents -// reading and writing to the directory once the caches are cleared. -func (policy *Policy) Deprovision() error { - return security.RemoveKey(policy.Description(), policy.Context.TargetUser) +// reading and writing to the directory --- unless the target keyring is a user +// keyring, in which case caches must be dropped too. +func (policy *Policy) Deprovision(allUsers bool) error { + return keyring.RemoveEncryptionKey(policy.Descriptor(), + policy.Context.getKeyringOptions(), allUsers) +} + +// NeedsUserKeyring returns true if Provision and Deprovision for this policy +// will use a user keyring, not a filesystem keyring. +func (policy *Policy) NeedsUserKeyring() bool { + return policy.Version() == 1 && !policy.Context.Config.GetUseFsKeyringForV1Policies() +} + +// NeedsRootToProvision returns true if Provision and Deprovision will require +// root for this policy in the current configuration. +func (policy *Policy) NeedsRootToProvision() bool { + return policy.Version() == 1 && policy.Context.Config.GetUseFsKeyringForV1Policies() +} + +// CanBeAppliedWithoutProvisioning returns true if this process can apply this +// policy to a directory without first calling Provision. +func (policy *Policy) CanBeAppliedWithoutProvisioning() bool { + return policy.Version() == 1 || util.IsUserRoot() } // commitData writes the Policy's current data to the filesystem. diff --git a/actions/protector.go b/actions/protector.go index fe5d694..4bd7c15 100644 --- a/actions/protector.go +++ b/actions/protector.go @@ -140,7 +140,11 @@ func CreateProtector(ctx *Context, name string, keyFn KeyFunc) (*Protector, erro if protector.key, err = crypto.NewRandomKey(metadata.InternalKeyLen); err != nil { return nil, err } - protector.data.ProtectorDescriptor = crypto.ComputeDescriptor(protector.key) + protector.data.ProtectorDescriptor, err = crypto.ComputeKeyDescriptor(protector.key, 1) + if err != nil { + protector.Lock() + return nil, err + } if err = protector.Rewrap(keyFn); err != nil { protector.Lock() diff --git a/cmd/fscrypt/commands.go b/cmd/fscrypt/commands.go index a3bfef2..41009b0 100644 --- a/cmd/fscrypt/commands.go +++ b/cmd/fscrypt/commands.go @@ -30,6 +30,7 @@ import ( "github.com/google/fscrypt/actions" "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/metadata" "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" @@ -134,11 +135,47 @@ func encryptAction(c *cli.Context) error { return nil } +// validateKeyringPrereqs ensures we're ready to add, remove, or get the status +// of the key for the given encryption policy (if policy != nil) or for the +// current default encryption policy (if policy == nil). +func validateKeyringPrereqs(ctx *actions.Context, policy *actions.Policy) error { + var policyVersion int64 + if policy == nil { + policyVersion = ctx.Config.Options.PolicyVersion + } else { + policyVersion = policy.Version() + } + // If it's a v2 policy, we're good to go, since non-root users can + // add/remove v2 policy keys directly to/from the filesystem, where they + // are usable by the filesystem on behalf of any process. + if policyVersion != 1 { + return nil + } + if ctx.Config.GetUseFsKeyringForV1Policies() { + // We'll be using the filesystem keyring, but it's a v1 + // encryption policy so root is required. + if !util.IsUserRoot() { + return ErrFsKeyringPerm + } + return nil + } + // We'll be using the target user's user keyring, so make sure a user + // was explicitly specified if the command is being run as root, and + // make sure that user's keyring is accessible. + if userFlag.Value == "" && util.IsUserRoot() { + return ErrSpecifyUser + } + if _, err := keyring.UserKeyringID(ctx.TargetUser, true); err != nil { + return err + } + return nil +} + // encryptPath sets up encryption on path and provisions the policy to the // keyring unless --skip-unlock is used. On failure, an error is returned, any // metadata creation is reverted, and the directory is unmodified. func encryptPath(path string) (err error) { - targetUser, err := parseUserFlag(!skipUnlockFlag.Value) + targetUser, err := parseUserFlag() if err != nil { return } @@ -154,10 +191,24 @@ func encryptPath(path string) (err error) { if policyFlag.Value != "" { log.Printf("getting policy for %q", path) - policy, err = getPolicyFromFlag(policyFlag.Value, ctx.TargetUser) + if policy, err = getPolicyFromFlag(policyFlag.Value, ctx.TargetUser); err != nil { + return + } + + if !skipUnlockFlag.Value { + if err = validateKeyringPrereqs(ctx, policy); err != nil { + return + } + } } else { log.Printf("creating policy for %q", path) + if !skipUnlockFlag.Value { + if err = validateKeyringPrereqs(ctx, nil); err != nil { + return + } + } + protector, created, protErr := selectOrCreateProtector(ctx) // Successfully created protector should be reverted on failure. if protErr != nil { @@ -173,28 +224,32 @@ func encryptPath(path string) (err error) { if err = protector.Unlock(existingKeyFn); err != nil { return } - policy, err = actions.CreatePolicy(ctx, protector) + if policy, err = actions.CreatePolicy(ctx, protector); err != nil { + return + } } // Successfully created policy should be reverted on failure. - if err != nil { - return - } defer func() { policy.Lock() if err != nil { - policy.Deprovision() + policy.Deprovision(false) policy.Revert() } }() - // Unlock() first, so if the Unlock() fails the directory isn't changed. - if !skipUnlockFlag.Value { + // Unlock() and Provision() first, so if that if these fail the + // directory isn't changed, and also because v2 policies can't be + // applied while deprovisioned unless the process is running as root. + if !skipUnlockFlag.Value || !policy.CanBeAppliedWithoutProvisioning() { if err = policy.Unlock(optionFn, existingKeyFn); err != nil { return } if err = policy.Provision(); err != nil { return } + if skipUnlockFlag.Value { + defer policy.Deprovision(false) + } } if err = policy.Apply(path); os.IsPermission(errors.Cause(err)) { // EACCES at this point indicates ownership issues. @@ -281,8 +336,8 @@ var Unlock = cli.Command{ appropriate key into the keyring. This requires unlocking one of the protectors protecting this directory (either by selecting a protector or specifying one with %s). This directory will be - locked again upon reboot, or after running "fscrypt purge" and - unmounting the corresponding filesystem.`, directoryArg, + locked again upon reboot, or after running "fscrypt lock" or + "fscrypt purge".`, directoryArg, shortDisplay(unlockWithFlag)), Flags: []cli.Flag{unlockWithFlag, keyFileFlag, userFlag}, Action: unlockAction, @@ -293,7 +348,7 @@ func unlockAction(c *cli.Context) error { return expectedArgsErr(c, 1, false) } - targetUser, err := parseUserFlag(true) + targetUser, err := parseUserFlag() if err != nil { return newExitError(c, err) } @@ -309,9 +364,14 @@ func unlockAction(c *cli.Context) error { if err != nil { return newExitError(c, err) } + // Ensure the keyring is ready. + if err = validateKeyringPrereqs(ctx, policy); err != nil { + return newExitError(c, err) + } // Check if directory is already unlocked - if policy.IsProvisioned() { - log.Printf("policy %s is already provisioned", policy.Descriptor()) + if policy.IsProvisionedByTargetUser() { + log.Printf("policy %s is already provisioned by %v", + policy.Descriptor(), ctx.TargetUser.Username) return newExitError(c, errors.Wrapf(ErrPolicyUnlocked, path)) } @@ -328,6 +388,97 @@ func unlockAction(c *cli.Context) error { return nil } +func dropCachesIfRequested(c *cli.Context, ctx *actions.Context) error { + if dropCachesFlag.Value { + if err := security.DropFilesystemCache(); err != nil { + return err + } + fmt.Fprintf(c.App.Writer, "Encrypted data removed from filesystem cache.\n") + } else { + fmt.Fprintf(c.App.Writer, "Filesystem %q should now be unmounted.\n", ctx.Mount.Path) + } + return nil +} + +// Lock takes an encrypted directory and locks it, undoing Unlock. +var Lock = cli.Command{ + Name: "lock", + ArgsUsage: directoryArg, + Usage: "lock an encrypted directory", + Description: fmt.Sprintf(`This command takes %s, an encrypted directory + which has been unlocked by fscrypt, and locks the directory by + removing the encryption key from the kernel. I.e., it undoes the + effect of 'fscrypt unlock'. + + For this to be effective, all files in the directory must first + be closed. + + If the directory uses a v1 encryption policy, then the %s=true + option may be needed to properly lock it. Root is required for + this. + + If the directory uses a v2 encryption policy, then a non-root + user can lock it, but only if it's the same user who unlocked it + originally and if no other users have unlocked it too. + + WARNING: even after the key has been removed, decrypted data may + still be present in freed memory, where it may still be + recoverable by an attacker who compromises system memory. To be + fully safe, you must reboot with a power cycle.`, + directoryArg, shortDisplay(dropCachesFlag)), + Flags: []cli.Flag{dropCachesFlag, userFlag, allUsersFlag}, + Action: lockAction, +} + +func lockAction(c *cli.Context) error { + if c.NArg() != 1 { + return expectedArgsErr(c, 1, false) + } + + targetUser, err := parseUserFlag() + if err != nil { + return newExitError(c, err) + } + path := c.Args().Get(0) + ctx, err := actions.NewContextFromPath(path, targetUser) + if err != nil { + return newExitError(c, err) + } + + log.Printf("performing sanity checks") + // Ensure path is encrypted and filesystem is using fscrypt. + policy, err := actions.GetPolicyFromPath(ctx, path) + if err != nil { + return newExitError(c, err) + } + // Ensure the keyring is ready. + if err = validateKeyringPrereqs(ctx, policy); err != nil { + return newExitError(c, err) + } + // Check if directory is already locked + if policy.IsFullyDeprovisioned() { + log.Printf("policy %s is already fully deprovisioned", policy.Descriptor()) + return newExitError(c, errors.Wrapf(ErrPolicyLocked, path)) + } + // Check for permission to drop caches, if it will be needed. + if policy.NeedsUserKeyring() && dropCachesFlag.Value && !util.IsUserRoot() { + return newExitError(c, ErrDropCachesPerm) + } + + if err = policy.Deprovision(allUsersFlag.Value); err != nil { + return newExitError(c, err) + } + + if policy.NeedsUserKeyring() { + if err = dropCachesIfRequested(c, ctx); err != nil { + return newExitError(c, err) + } + } + + fmt.Fprintf(c.App.Writer, "%q is now locked.\n", path) + return nil +} + // Purge removes all the policy keys from the keyring (also need unmount). var Purge = cli.Command{ Name: "purge", @@ -377,7 +528,7 @@ func purgeAction(c *cli.Context) error { } } - targetUser, err := parseUserFlag(true) + targetUser, err := parseUserFlag() if err != nil { return newExitError(c, err) } @@ -386,6 +537,9 @@ func purgeAction(c *cli.Context) error { if err != nil { return newExitError(c, err) } + if err = validateKeyringPrereqs(ctx, nil); err != nil { + return newExitError(c, err) + } question := fmt.Sprintf("Purge all policy keys from %q", ctx.Mount.Path) if dropCachesFlag.Value { @@ -401,13 +555,8 @@ func purgeAction(c *cli.Context) error { } fmt.Fprintf(c.App.Writer, "Policies purged for %q.\n", ctx.Mount.Path) - if dropCachesFlag.Value { - if err = security.DropFilesystemCache(); err != nil { - return newExitError(c, err) - } - fmt.Fprintf(c.App.Writer, "Encrypted data removed from filesystem cache.\n") - } else { - fmt.Fprintf(c.App.Writer, "Filesystem %q should now be unmounted.\n", ctx.Mount.Path) + if err = dropCachesIfRequested(c, ctx); err != nil { + return newExitError(c, err) } return nil } @@ -527,7 +676,7 @@ func createProtectorAction(c *cli.Context) error { return expectedArgsErr(c, 1, false) } - targetUser, err := parseUserFlag(false) + targetUser, err := parseUserFlag() if err != nil { return newExitError(c, err) } diff --git a/cmd/fscrypt/errors.go b/cmd/fscrypt/errors.go index 288e697..5239155 100644 --- a/cmd/fscrypt/errors.go +++ b/cmd/fscrypt/errors.go @@ -34,8 +34,8 @@ import ( "github.com/google/fscrypt/actions" "github.com/google/fscrypt/crypto" "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/metadata" - "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" ) @@ -56,12 +56,14 @@ var ( ErrAllLoadsFailed = errors.New("could not load any protectors") ErrMustBeRoot = errors.New("this command must be run as root") ErrPolicyUnlocked = errors.New("this file or directory is already unlocked") + ErrPolicyLocked = errors.New("this file or directory is already locked") ErrBadOwners = errors.New("you do not own this directory") ErrNotEmptyDir = errors.New("not an empty directory") ErrNotPassphrase = errors.New("protector does not use a passphrase") ErrUnknownUser = errors.New("unknown user") ErrDropCachesPerm = errors.New("inode cache can only be dropped as root") ErrSpecifyUser = errors.New("user must be specified when run as root") + ErrFsKeyringPerm = errors.New("root is required to add/remove v1 encryption policy keys to/from filesystem") ) var loadHelpText = fmt.Sprintf("You may need to mount a linked filesystem. Run with %s for more information.", shortDisplay(verboseFlag)) @@ -94,11 +96,20 @@ func getErrorSuggestions(err error) string { needs to be enabled for this filesystem. See the documentation on how to enable encryption on ext4 systems (and the risks of doing so).` - case security.ErrSessionUserKeying: + case keyring.ErrKeyFilesOpen: + return `Directory was incompletely locked because some files are + still open. These files remain accessible. Try killing + any processes using files in the directory, then + re-running 'fscrypt lock'.` + case keyring.ErrKeyAddedByOtherUsers: + return `Directory couldn't be fully locked because other user(s) + have unlocked it. If you want to force the directory to + be locked, use 'sudo fscrypt lock --all-users DIR'.` + case keyring.ErrSessionUserKeying: return `This is usually the result of a bad PAM configuration. Either correct the problem in your PAM stack, enable pam_keyinit.so, or run "keyctl link @u @s".` - case security.ErrAccessUserKeyring: + case keyring.ErrAccessUserKeyring: return fmt.Sprintf(`You can only use %s to access the user keyring of another user if you are running as root.`, shortDisplay(userFlag)) @@ -135,6 +146,13 @@ func getErrorSuggestions(err error) string { properly clear the inode cache, or it should be run with %s=false (this may leave encrypted files and directories in an accessible state).`, shortDisplay(dropCachesFlag)) + case ErrFsKeyringPerm: + return `Either this command should be run as root, or you should + set '"use_fs_keyring_for_v1_policies": false' in + /etc/fscrypt.conf, or you should re-create your + encrypted directories using v2 encryption policies + rather than v1 (this requires setting '"policy_version": + "2"' in the "options" section of /etc/fscrypt.conf).` case ErrSpecifyUser: return fmt.Sprintf(`When running this command as root, you usually still want to provision/remove keys for a normal diff --git a/cmd/fscrypt/flags.go b/cmd/fscrypt/flags.go index 16a75dc..b7933c9 100644 --- a/cmd/fscrypt/flags.go +++ b/cmd/fscrypt/flags.go @@ -33,7 +33,6 @@ import ( "github.com/urfave/cli" "github.com/google/fscrypt/actions" - "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" ) @@ -117,7 +116,7 @@ var ( allFlags = []prettyFlag{helpFlag, versionFlag, verboseFlag, quietFlag, forceFlag, legacyFlag, skipUnlockFlag, timeTargetFlag, sourceFlag, nameFlag, keyFileFlag, protectorFlag, - unlockWithFlag, policyFlag} + unlockWithFlag, policyFlag, allUsersFlag} // universalFlags contains flags that should be on every command universalFlags = []cli.Flag{verboseFlag, quietFlag, helpFlag} ) @@ -163,12 +162,22 @@ var ( } dropCachesFlag = &boolFlag{ Name: "drop-caches", - Usage: `After purging the keys from the keyring, drop the - associated caches for the purge to take effect. Without - this flag, cached encrypted files may still have their - plaintext visible. Requires root privileges.`, + Usage: `After removing the key(s) from the keyring, drop the + kernel's filesystem caches if needed. Without this flag, + files encrypted with v1 encryption policies may still be + accessible. This flag is not needed for v2 encryption + policies. This flag, if actually needed, requires root + privileges.`, Default: true, } + allUsersFlag = &boolFlag{ + Name: "all-users", + Usage: `Lock the directory no matter which user(s) have unlocked + it. Requires root privileges. This flag is only + necessary if the directory was unlocked by a user + different from the one you're locking it as. This flag + is only implemented for v2 encryption policies.`, + } ) // Option flags: used to specify options instead of being prompted for them @@ -283,24 +292,10 @@ func getPolicyFromFlag(flagValue string, targetUser *user.User) (*actions.Policy } // parseUserFlag returns the user specified by userFlag or the current effective -// user if the flag value is missing. If the effective user is root, however, a -// user must specified in the flag. If checkKeyring is true, we also make sure -// there are no problems accessing the user keyring. -func parseUserFlag(checkKeyring bool) (targetUser *user.User, err error) { +// user if the flag value is missing. +func parseUserFlag() (targetUser *user.User, err error) { if userFlag.Value != "" { - targetUser, err = user.Lookup(userFlag.Value) - } else { - if util.IsUserRoot() { - return nil, ErrSpecifyUser - } - targetUser, err = util.EffectiveUser() - } - if err != nil { - return nil, err - } - - if checkKeyring { - _, err = security.UserKeyringID(targetUser, true) + return user.Lookup(userFlag.Value) } - return targetUser, err + return util.EffectiveUser() } diff --git a/cmd/fscrypt/fscrypt.go b/cmd/fscrypt/fscrypt.go index 9ac8e2f..b6549f4 100644 --- a/cmd/fscrypt/fscrypt.go +++ b/cmd/fscrypt/fscrypt.go @@ -76,7 +76,7 @@ func main() { // Initialize command list and setup all of the commands. app.Action = defaultAction - app.Commands = []cli.Command{Setup, Encrypt, Unlock, Purge, Status, Metadata} + app.Commands = []cli.Command{Setup, Encrypt, Unlock, Lock, Purge, Status, Metadata} for i := range app.Commands { setupCommand(&app.Commands[i]) } diff --git a/cmd/fscrypt/protector.go b/cmd/fscrypt/protector.go index 8cbcf03..25f1984 100644 --- a/cmd/fscrypt/protector.go +++ b/cmd/fscrypt/protector.go @@ -26,6 +26,7 @@ import ( "github.com/google/fscrypt/actions" "github.com/google/fscrypt/filesystem" "github.com/google/fscrypt/metadata" + "github.com/google/fscrypt/util" ) // createProtector makes a new protector on either ctx.Mount or if the requested @@ -37,6 +38,11 @@ func createProtectorFromContext(ctx *actions.Context) (*actions.Protector, error } log.Printf("using source: %s", ctx.Config.Source.String()) + if ctx.Config.Source == metadata.SourceType_pam_passphrase && + userFlag.Value == "" && util.IsUserRoot() { + return nil, ErrSpecifyUser + } + name, err := promptForName(ctx) if err != nil { return nil, err diff --git a/cmd/fscrypt/status.go b/cmd/fscrypt/status.go index 375899b..bf11495 100644 --- a/cmd/fscrypt/status.go +++ b/cmd/fscrypt/status.go @@ -31,6 +31,7 @@ import ( "github.com/google/fscrypt/actions" "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/metadata" ) @@ -65,6 +66,19 @@ func yesNoString(b bool) string { return "No" } +func policyUnlockedStatus(policy *actions.Policy) string { + switch policy.GetProvisioningStatus() { + case keyring.KeyPresent, keyring.KeyPresentButOnlyOtherUsers: + return "Yes" + case keyring.KeyAbsent: + return "No" + case keyring.KeyAbsentButFilesBusy: + return "Partially (incompletely locked)" + default: + return "Unknown" + } +} + // writeGlobalStatus prints all the filesystems that use (or could use) fscrypt. func writeGlobalStatus(w io.Writer) error { mounts, err := filesystem.AllFilesystems() @@ -160,7 +174,7 @@ func writeFilesystemStatus(w io.Writer, ctx *actions.Context) error { continue } - fmt.Fprintf(t, "%s\t%s\t%s\n", descriptor, yesNoString(policy.IsProvisioned()), + fmt.Fprintf(t, "%s\t%s\t%s\n", descriptor, policyUnlockedStatus(policy), strings.Join(policy.ProtectorDescriptors(), ", ")) } return t.Flush() @@ -180,7 +194,7 @@ func writePathStatus(w io.Writer, path string) error { fmt.Fprintln(w) fmt.Fprintf(w, "Policy: %s\n", policy.Descriptor()) fmt.Fprintf(w, "Options: %s\n", policy.Options()) - fmt.Fprintf(w, "Unlocked: %s\n", yesNoString(policy.IsProvisioned())) + fmt.Fprintf(w, "Unlocked: %s\n", policyUnlockedStatus(policy)) fmt.Fprintln(w) options := policy.ProtectorOptions() diff --git a/crypto/crypto.go b/crypto/crypto.go index 8de8134..9a138d0 100644 --- a/crypto/crypto.go +++ b/crypto/crypto.go @@ -28,7 +28,7 @@ // - key stretching (SHA256-based HKDF) // - key wrapping/unwrapping (Encrypt then MAC) // - passphrase-based key derivation (Argon2id) -// - descriptor computation (double SHA512) +// - key descriptor computation (double SHA512, or HKDF-SHA512) package crypto import ( @@ -38,6 +38,7 @@ import ( "crypto/sha256" "crypto/sha512" "encoding/hex" + "io" "github.com/pkg/errors" "golang.org/x/crypto/argon2" @@ -167,7 +168,7 @@ func Unwrap(wrappingKey *Key, data *metadata.WrappedKeyData) (*Key, error) { return nil, ErrBadAuth } - secretKey, err := newBlankKey(len(data.EncryptedKey)) + secretKey, err := NewBlankKey(len(data.EncryptedKey)) if err != nil { return nil, err } @@ -176,16 +177,42 @@ func Unwrap(wrappingKey *Key, data *metadata.WrappedKeyData) (*Key, error) { return secretKey, nil } -// ComputeDescriptor computes the descriptor for a given cryptographic key. In -// keeping with the process used in e4crypt, this uses the initial bytes -// (formatted as hexadecimal) of the double application of SHA512 on the key. -func ComputeDescriptor(key *Key) string { +func computeKeyDescriptorV1(key *Key) string { h1 := sha512.Sum512(key.data) h2 := sha512.Sum512(h1[:]) - length := hex.DecodedLen(metadata.DescriptorLen) + length := hex.DecodedLen(metadata.PolicyDescriptorLenV1) return hex.EncodeToString(h2[:length]) } +func computeKeyDescriptorV2(key *Key) (string, error) { + // This algorithm is specified by the kernel. It uses unsalted + // HKDF-SHA512, where the application-information string is the prefix + // "fscrypt\0" followed by the HKDF_CONTEXT_KEY_IDENTIFIER byte. + hkdf := hkdf.New(sha512.New, key.data, nil, []byte("fscrypt\x00\x01")) + h := make([]byte, hex.DecodedLen(metadata.PolicyDescriptorLenV2)) + if _, err := io.ReadFull(hkdf, h); err != nil { + return "", err + } + return hex.EncodeToString(h), nil +} + +// ComputeKeyDescriptor computes the descriptor for a given cryptographic key. +// If policyVersion=1, it uses the first 8 bytes of the double application of +// SHA512 on the key. Use this for protectors and v1 policy keys. +// If policyVersion=2, it uses HKDF-SHA512 to compute a key identifier that's +// compatible with the kernel's key identifiers for v2 policy keys. +// In both cases, the resulting bytes are formatted as hex. +func ComputeKeyDescriptor(key *Key, policyVersion int64) (string, error) { + switch policyVersion { + case 1: + return computeKeyDescriptorV1(key), nil + case 2: + return computeKeyDescriptorV2(key) + default: + return "", errors.Errorf("policy version of %d is invalid", policyVersion) + } +} + // PassphraseHash uses Argon2id to produce a Key given the passphrase, salt, and // hashing costs. This method is designed to take a long time and consume // considerable memory. For more information, see the documentation at @@ -196,7 +223,7 @@ func PassphraseHash(passphrase *Key, salt []byte, costs *metadata.HashingCosts) p := uint8(costs.Parallelism) key := argon2.IDKey(passphrase.data, salt, t, m, p, metadata.InternalKeyLen) - hash, err := newBlankKey(metadata.InternalKeyLen) + hash, err := NewBlankKey(metadata.InternalKeyLen) if err != nil { return nil, err } diff --git a/crypto/crypto_test.go b/crypto/crypto_test.go index 6f973ef..6eb0b02 100644 --- a/crypto/crypto_test.go +++ b/crypto/crypto_test.go @@ -30,11 +30,7 @@ import ( "os" "testing" - "golang.org/x/sys/unix" - "github.com/google/fscrypt/metadata" - "github.com/google/fscrypt/security" - "github.com/google/fscrypt/util" ) // Reader that always returns the same byte @@ -53,16 +49,11 @@ func makeKey(b byte, n int) (*Key, error) { } var ( - fakeValidDescriptor = "0123456789abcdef" - fakeSalt = bytes.Repeat([]byte{'a'}, metadata.SaltLen) - fakePassword = []byte("password") - defaultService = unix.FSCRYPT_KEY_DESC_PREFIX - - fakeValidPolicyKey, _ = makeKey(42, metadata.PolicyKeyLen) - fakeInvalidPolicyKey, _ = makeKey(42, metadata.PolicyKeyLen-1) - fakeWrappingKey, _ = makeKey(17, metadata.InternalKeyLen) + fakeSalt = bytes.Repeat([]byte{'a'}, metadata.SaltLen) + fakePassword = []byte("password") - testUser, _ = util.EffectiveUser() + fakeValidPolicyKey, _ = makeKey(42, metadata.PolicyKeyLen) + fakeWrappingKey, _ = makeKey(17, metadata.InternalKeyLen) ) // As the passphrase hashing function clears the passphrase, we need to make @@ -242,43 +233,6 @@ func TestKeyLargeResize(t *testing.T) { } } -// Adds and removes a key with various services. -func TestAddRemoveKeys(t *testing.T) { - for _, service := range []string{defaultService, "ext4:", "f2fs:"} { - validDescription := service + fakeValidDescriptor - if err := InsertPolicyKey(fakeValidPolicyKey, validDescription, testUser); err != nil { - t.Error(err) - } - if err := security.RemoveKey(validDescription, testUser); err != nil { - t.Error(err) - } - } -} - -// Adds a key twice (both should succeed) -func TestAddTwice(t *testing.T) { - validDescription := defaultService + fakeValidDescriptor - InsertPolicyKey(fakeValidPolicyKey, validDescription, testUser) - if InsertPolicyKey(fakeValidPolicyKey, validDescription, testUser) != nil { - t.Error("InsertPolicyKey should not fail if key already exists") - } - security.RemoveKey(validDescription, testUser) -} - -// Makes sure a key fails with bad policy or service -func TestBadAddKeys(t *testing.T) { - validDescription := defaultService + fakeValidDescriptor - if InsertPolicyKey(fakeInvalidPolicyKey, validDescription, testUser) == nil { - security.RemoveKey(validDescription, testUser) - t.Error("InsertPolicyKey should fail with bad policy key") - } - invalidDescription := "ext4" + fakeValidDescriptor - if InsertPolicyKey(fakeValidPolicyKey, invalidDescription, testUser) == nil { - security.RemoveKey(invalidDescription, testUser) - t.Error("InsertPolicyKey should fail with bad service") - } -} - // Check that we can create random keys. All this test does to test the // "randomness" is generate a page of random bytes and attempts compression. // If the data can be compressed it is probably not very random. This isn't @@ -510,6 +464,33 @@ func TestUnwrapWrongData(t *testing.T) { } } +func TestComputeKeyDescriptorV1(t *testing.T) { + descriptor, err := ComputeKeyDescriptor(fakeValidPolicyKey, 1) + if err != nil { + t.Fatal(err) + } + if descriptor != "8290608a029c5aae" { + t.Errorf("wrong v1 descriptor: %s", descriptor) + } +} + +func TestComputeKeyDescriptorV2(t *testing.T) { + descriptor, err := ComputeKeyDescriptor(fakeValidPolicyKey, 2) + if err != nil { + t.Fatal(err) + } + if descriptor != "2139f52bf8386ee99845818ac7e91c4a" { + t.Errorf("wrong v2 descriptor: %s", descriptor) + } +} + +func TestComputeKeyDescriptorBadVersion(t *testing.T) { + _, err := ComputeKeyDescriptor(fakeValidPolicyKey, 0) + if err == nil { + t.Error("computing key descriptor with bad version should fail") + } +} + // Run our test cases for passphrase hashing func TestPassphraseHashing(t *testing.T) { for i, testCase := range hashTestCases { diff --git a/crypto/key.go b/crypto/key.go index 52efb54..2220652 100644 --- a/crypto/key.go +++ b/crypto/key.go @@ -33,7 +33,6 @@ import ( "io" "log" "os" - "os/user" "runtime" "unsafe" @@ -41,7 +40,6 @@ import ( "golang.org/x/sys/unix" "github.com/google/fscrypt/metadata" - "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" ) @@ -94,9 +92,9 @@ type Key struct { data []byte } -// newBlankKey constructs a blank key of a specified length and returns an error +// NewBlankKey constructs a blank key of a specified length and returns an error // if we are unable to allocate or lock the necessary memory. -func newBlankKey(length int) (*Key, error) { +func NewBlankKey(length int) (*Key, error) { if length == 0 { return &Key{data: nil}, nil } else if length < 0 { @@ -167,7 +165,7 @@ func (key *Key) resize(requestedSize int) (*Key, error) { } defer key.Wipe() - resizedKey, err := newBlankKey(requestedSize) + resizedKey, err := NewBlankKey(requestedSize) if err != nil { return nil, err } @@ -175,6 +173,18 @@ func (key *Key) resize(requestedSize int) (*Key, error) { return resizedKey, nil } +// Data returns a slice of the key's underlying data. Note that this may become +// outdated if the key is resized. +func (key *Key) Data() []byte { + return key.data +} + +// UnsafePtr returns an unsafe pointer to the key's underlying data. Note that +// this will only be valid as long as the key is not resized. +func (key *Key) UnsafePtr() unsafe.Pointer { + return util.Ptr(key.data) +} + // UnsafeToCString makes a copy of the string's data into a null-terminated C // string allocated by C. Note that this method is unsafe as this C copy has no // locking or wiping functionality. The key shouldn't contain any `\0` bytes. @@ -190,7 +200,7 @@ func (key *Key) UnsafeToCString() unsafe.Pointer { // ensure that this original copy is secured. func NewKeyFromCString(str unsafe.Pointer) (*Key, error) { size := C.strlen((*C.char)(str)) - key, err := newBlankKey(int(size)) + key, err := NewBlankKey(int(size)) if err != nil { return nil, err } @@ -203,7 +213,7 @@ func NewKeyFromCString(str unsafe.Pointer) (*Key, error) { func NewKeyFromReader(reader io.Reader) (*Key, error) { // Use an initial key size of a page. As Mmap allocates a page anyway, // there isn't much additional overhead from starting with a whole page. - key, err := newBlankKey(os.Getpagesize()) + key, err := NewBlankKey(os.Getpagesize()) if err != nil { return nil, err } @@ -235,7 +245,7 @@ func NewKeyFromReader(reader io.Reader) (*Key, error) { // NewFixedLengthKeyFromReader constructs a key with a specified length by // reading exactly length bytes from reader. func NewFixedLengthKeyFromReader(reader io.Reader, length int) (*Key, error) { - key, err := newBlankKey(length) + key, err := NewBlankKey(length) if err != nil { return nil, err } @@ -246,30 +256,6 @@ func NewFixedLengthKeyFromReader(reader io.Reader, length int) (*Key, error) { return key, nil } -// InsertPolicyKey puts the provided policy key into the kernel keyring with the -// provided description, and type logon. The key must be a policy key. -func InsertPolicyKey(key *Key, description string, targetUser *user.User) error { - if err := util.CheckValidLength(metadata.PolicyKeyLen, key.Len()); err != nil { - return errors.Wrap(err, "policy key") - } - - // Create our payload (containing an FscryptKey) - payload, err := newBlankKey(int(unsafe.Sizeof(unix.FscryptKey{}))) - if err != nil { - return err - } - defer payload.Wipe() - - // Cast the payload to an FscryptKey so we can initialize the fields. - fscryptKey := (*unix.FscryptKey)(util.Ptr(payload.data)) - // Mode is ignored by the kernel - fscryptKey.Mode = 0 - fscryptKey.Size = metadata.PolicyKeyLen - copy(fscryptKey.Raw[:], key.data) - - return security.InsertKey(payload.data, description, targetUser) -} - var ( // The recovery code is base32 with a dash between each block of 8 characters. encoding = base32.StdEncoding @@ -290,7 +276,7 @@ func WriteRecoveryCode(key *Key, writer io.Writer) error { } // We store the base32 encoded data (without separators) in a temp key - encodedKey, err := newBlankKey(encodedLength) + encodedKey, err := NewBlankKey(encodedLength) if err != nil { return err } @@ -318,7 +304,7 @@ func WriteRecoveryCode(key *Key, writer io.Writer) error { // be given the same level of protection as a raw cryptographic key. func ReadRecoveryCode(reader io.Reader) (*Key, error) { // We store the base32 encoded data (without separators) in a temp key - encodedKey, err := newBlankKey(encodedLength) + encodedKey, err := NewBlankKey(encodedLength) if err != nil { return nil, err } @@ -347,7 +333,7 @@ func ReadRecoveryCode(reader io.Reader) (*Key, error) { } // Now we decode the key, resizing if necessary - decodedKey, err := newBlankKey(decodedLength) + decodedKey, err := NewBlankKey(decodedLength) if err != nil { return nil, err } diff --git a/keyring/fs_keyring.go b/keyring/fs_keyring.go new file mode 100644 index 0000000..42c1648 --- /dev/null +++ b/keyring/fs_keyring.go @@ -0,0 +1,318 @@ +/* + * fs_keyring.go - Add/remove encryption policy keys to/from filesystem + * + * Copyright 2019 Google LLC + * Author: Eric Biggers (ebiggers@google.com) + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may not + * use this file except in compliance with the License. You may obtain a copy of + * the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations under + * the License. + */ + +package keyring + +/* +#include <string.h> +*/ +import "C" + +import ( + "encoding/hex" + "log" + "os" + "os/user" + "sync" + "unsafe" + + "github.com/pkg/errors" + "golang.org/x/sys/unix" + + "github.com/google/fscrypt/crypto" + "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/security" + "github.com/google/fscrypt/util" +) + +var ( + fsKeyringSupported bool + fsKeyringSupportedKnown bool + fsKeyringSupportedLock sync.Mutex +) + +func checkForFsKeyringSupport(mount *filesystem.Mount) bool { + dir, err := os.Open(mount.Path) + if err != nil { + log.Printf("Unexpected error opening %q. Assuming filesystem keyring is unsupported.", + mount.Path) + return false + } + defer dir.Close() + + // FS_IOC_ADD_ENCRYPTION_KEY with a NULL argument will fail with ENOTTY + // if the ioctl isn't supported. Otherwise it should fail with EFAULT. + // + // Note that there's no need to check for FS_IOC_REMOVE_ENCRYPTION_KEY + // support separately, since it's guaranteed to be available if + // FS_IOC_ADD_ENCRYPTION_KEY is. There's also no need to check for + // support on every filesystem separately, since either the kernel + // supports the ioctls on all fscrypt-capable filesystems or it doesn't. + _, _, errno := unix.Syscall(unix.SYS_IOCTL, dir.Fd(), unix.FS_IOC_ADD_ENCRYPTION_KEY, 0) + if errno == unix.ENOTTY { + log.Printf("Kernel doesn't support filesystem keyring. Falling back to user keyring.") + return false + } + if errno == unix.EFAULT { + log.Printf("Detected support for filesystem keyring") + } else { + // EFAULT is expected, but as long as we didn't get ENOTTY the + // ioctl should be available. + log.Printf("Unexpected error from FS_IOC_ADD_ENCRYPTION_KEY(%q, NULL): %v", mount.Path, errno) + } + return true +} + +// isFsKeyringSupported returns true if the kernel supports the ioctls to +// add/remove fscrypt keys directly to/from the filesystem. For support to be +// detected, the given Mount must be for a filesystem that supports fscrypt. +func isFsKeyringSupported(mount *filesystem.Mount) bool { + fsKeyringSupportedLock.Lock() + defer fsKeyringSupportedLock.Unlock() + if !fsKeyringSupportedKnown { + fsKeyringSupported = checkForFsKeyringSupport(mount) + fsKeyringSupportedKnown = true + } + return fsKeyringSupported +} + +// buildKeySpecifier converts the key descriptor string to an FscryptKeySpecifier. +func buildKeySpecifier(spec *unix.FscryptKeySpecifier, descriptor string) error { + descriptorBytes, err := hex.DecodeString(descriptor) + if err != nil { + return errors.Errorf("key descriptor %q is invalid", descriptor) + } + switch len(descriptorBytes) { + case unix.FSCRYPT_KEY_DESCRIPTOR_SIZE: + spec.Type = unix.FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR + case unix.FSCRYPT_KEY_IDENTIFIER_SIZE: + spec.Type = unix.FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER + default: + return errors.Errorf("key descriptor %q has unknown length", descriptor) + } + copy(spec.U[:], descriptorBytes) + return nil +} + +type savedPrivs struct { + ruid, euid, suid int +} + +// dropPrivsIfNeeded drops privileges (UIDs only) to the given user if we're +// working with a v2 policy key, and if the user is different from the user the +// process is currently running as. +// +// This is needed to change the effective UID so that FS_IOC_ADD_ENCRYPTION_KEY +// and FS_IOC_REMOVE_ENCRYPTION_KEY will add/remove a claim to the key for the +// intended user, and so that FS_IOC_GET_ENCRYPTION_KEY_STATUS will return the +// correct status flags for the user. +func dropPrivsIfNeeded(user *user.User, spec *unix.FscryptKeySpecifier) (*savedPrivs, error) { + if spec.Type == unix.FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR { + // v1 policy keys don't have any concept of user claims. + return nil, nil + } + targetUID := util.AtoiOrPanic(user.Uid) + ruid, euid, suid := security.GetUids() + if euid == targetUID { + return nil, nil + } + if err := security.SetUids(targetUID, targetUID, euid); err != nil { + return nil, err + } + return &savedPrivs{ruid, euid, suid}, nil +} + +// restorePrivs restores root privileges if needed. +func restorePrivs(privs *savedPrivs) error { + if privs != nil { + return security.SetUids(privs.ruid, privs.euid, privs.suid) + } + return nil +} + +// validateKeyDescriptor validates that the correct key descriptor was provided. +// This isn't really necessary; this is just an extra sanity check. +func validateKeyDescriptor(spec *unix.FscryptKeySpecifier, descriptor string) (string, error) { + if spec.Type != unix.FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER { + // v1 policy key: the descriptor is chosen arbitrarily by + // userspace, so there's nothing to validate. + return descriptor, nil + } + // v2 policy key. The descriptor ("identifier" in the kernel UAPI) is + // calculated as a cryptographic hash of the key itself. The kernel + // ignores the provided value, and calculates and returns it itself. So + // verify that the returned value is as expected. If it's not, the key + // doesn't actually match the encryption policy we thought it was for. + actual := hex.EncodeToString(spec.U[:unix.FSCRYPT_KEY_IDENTIFIER_SIZE]) + if descriptor == actual { + return descriptor, nil + } + return actual, + errors.Errorf("provided and actual key descriptors differ (%q != %q)", + descriptor, actual) +} + +// fsAddEncryptionKey adds the specified encryption key to the specified filesystem. +func fsAddEncryptionKey(key *crypto.Key, descriptor string, + mount *filesystem.Mount, user *user.User) error { + + dir, err := os.Open(mount.Path) + if err != nil { + return err + } + defer dir.Close() + + argKey, err := crypto.NewBlankKey(int(unsafe.Sizeof(unix.FscryptAddKeyArg{})) + key.Len()) + if err != nil { + return err + } + defer argKey.Wipe() + arg := (*unix.FscryptAddKeyArg)(argKey.UnsafePtr()) + + if err = buildKeySpecifier(&arg.Key_spec, descriptor); err != nil { + return err + } + + raw := unsafe.Pointer(uintptr(argKey.UnsafePtr()) + unsafe.Sizeof(*arg)) + arg.Raw_size = uint32(key.Len()) + C.memcpy(raw, key.UnsafePtr(), C.size_t(key.Len())) + + savedPrivs, err := dropPrivsIfNeeded(user, &arg.Key_spec) + if err != nil { + return err + } + _, _, errno := unix.Syscall(unix.SYS_IOCTL, dir.Fd(), + unix.FS_IOC_ADD_ENCRYPTION_KEY, uintptr(argKey.UnsafePtr())) + restorePrivs(savedPrivs) + + log.Printf("FS_IOC_ADD_ENCRYPTION_KEY(%q, %s, <raw>) = %v", mount.Path, descriptor, errno) + if errno != 0 { + return errors.Wrap(ErrKeyAdd, errno.Error()) + } + if descriptor, err = validateKeyDescriptor(&arg.Key_spec, descriptor); err != nil { + fsRemoveEncryptionKey(descriptor, mount, user) + return err + } + return nil +} + +// fsRemoveEncryptionKey removes the specified encryption key from the specified +// filesystem. +func fsRemoveEncryptionKey(descriptor string, mount *filesystem.Mount, + user *user.User) error { + + dir, err := os.Open(mount.Path) + if err != nil { + return err + } + defer dir.Close() + + var arg unix.FscryptRemoveKeyArg + if err = buildKeySpecifier(&arg.Key_spec, descriptor); err != nil { + return err + } + + ioc := unix.FS_IOC_REMOVE_ENCRYPTION_KEY + iocName := "FS_IOC_REMOVE_ENCRYPTION_KEY" + var savedPrivs *savedPrivs + if user == nil { + ioc = unix.FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS + iocName = "FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS" + } else { + savedPrivs, err = dropPrivsIfNeeded(user, &arg.Key_spec) + if err != nil { + return err + } + } + _, _, errno := unix.Syscall(unix.SYS_IOCTL, dir.Fd(), uintptr(ioc), uintptr(unsafe.Pointer(&arg))) + restorePrivs(savedPrivs) + + log.Printf("%s(%q, %s) = %v, removal_status_flags=0x%x", + iocName, mount.Path, descriptor, errno, arg.Removal_status_flags) + switch errno { + case 0: + switch { + case arg.Removal_status_flags&unix.FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS != 0: + return ErrKeyAddedByOtherUsers + case arg.Removal_status_flags&unix.FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY != 0: + return ErrKeyFilesOpen + } + return nil + case unix.ENOKEY: + // ENOKEY means either the key is completely missing or that the + // current user doesn't have a claim to it. Distinguish between + // these two cases by getting the key status. + if user != nil { + status, _ := fsGetEncryptionKeyStatus(descriptor, mount, user) + if status == KeyPresentButOnlyOtherUsers { + return ErrKeyAddedByOtherUsers + } + } + return ErrKeyNotPresent + default: + return errors.Wrap(ErrKeyRemove, errno.Error()) + } +} + +// fsGetEncryptionKeyStatus gets the status of the specified encryption key on +// the specified filesystem. +func fsGetEncryptionKeyStatus(descriptor string, mount *filesystem.Mount, + user *user.User) (KeyStatus, error) { + + dir, err := os.Open(mount.Path) + if err != nil { + return KeyStatusUnknown, err + } + defer dir.Close() + + var arg unix.FscryptGetKeyStatusArg + err = buildKeySpecifier(&arg.Key_spec, descriptor) + if err != nil { + return KeyStatusUnknown, err + } + + savedPrivs, err := dropPrivsIfNeeded(user, &arg.Key_spec) + if err != nil { + return KeyStatusUnknown, err + } + _, _, errno := unix.Syscall(unix.SYS_IOCTL, dir.Fd(), + unix.FS_IOC_GET_ENCRYPTION_KEY_STATUS, uintptr(unsafe.Pointer(&arg))) + restorePrivs(savedPrivs) + + log.Printf("FS_IOC_GET_ENCRYPTION_KEY_STATUS(%q, %s) = %v, status=%d, status_flags=0x%x", + mount.Path, descriptor, errno, arg.Status, arg.Status_flags) + if errno != 0 { + return KeyStatusUnknown, errors.Wrap(ErrKeySearch, errno.Error()) + } + switch arg.Status { + case unix.FSCRYPT_KEY_STATUS_ABSENT: + return KeyAbsent, nil + case unix.FSCRYPT_KEY_STATUS_PRESENT: + if arg.Key_spec.Type != unix.FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR && + (arg.Status_flags&unix.FSCRYPT_KEY_STATUS_FLAG_ADDED_BY_SELF) == 0 { + return KeyPresentButOnlyOtherUsers, nil + } + return KeyPresent, nil + case unix.FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED: + return KeyAbsentButFilesBusy, nil + default: + return KeyStatusUnknown, + errors.Wrapf(ErrKeySearch, "unknown key status (%d)", arg.Status) + } +} diff --git a/keyring/keyring.go b/keyring/keyring.go new file mode 100644 index 0000000..5a75153 --- /dev/null +++ b/keyring/keyring.go @@ -0,0 +1,155 @@ +/* + * keyring.go - Add/remove encryption policy keys to/from kernel + * + * Copyright 2019 Google LLC + * Author: Eric Biggers (ebiggers@google.com) + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may not + * use this file except in compliance with the License. You may obtain a copy of + * the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations under + * the License. + */ + +// Package keyring manages adding, removing, and getting the status of +// encryption policy keys to/from the kernel. Most public functions are in +// keyring.go, and they delegate to either user_keyring.go or fs_keyring.go, +// depending on whether a user keyring or a filesystem keyring is being used. +// +// v2 encryption policies always use the filesystem keyring. +// v1 policies use the user keyring by default, but can be configured to use the +// filesystem keyring instead (requires root and kernel v5.4+). +package keyring + +import ( + "encoding/hex" + "os/user" + "strconv" + + "github.com/pkg/errors" + "golang.org/x/sys/unix" + + "github.com/google/fscrypt/crypto" + "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/metadata" + "github.com/google/fscrypt/util" +) + +// Keyring error values +var ( + ErrKeyAdd = util.SystemError("could not add key to the keyring") + ErrKeyRemove = util.SystemError("could not remove key from the keyring") + ErrKeyNotPresent = errors.New("key not present or already removed") + ErrKeyFilesOpen = errors.New("some files using the key are still open") + ErrKeyAddedByOtherUsers = errors.New("other users have added the key too") + ErrKeySearch = errors.New("could not find key with descriptor") + ErrSessionUserKeying = errors.New("user keyring not linked into session keyring") + ErrAccessUserKeyring = errors.New("could not access user keyring") + ErrLinkUserKeyring = util.SystemError("could not link user keyring into root keyring") +) + +// Options are the options which specify *which* keyring the key should be +// added/removed/gotten to, and how. +type Options struct { + // Mount is the filesystem to which the key should be + // added/removed/gotten. + Mount *filesystem.Mount + // User is the user for whom the key should be added/removed/gotten. + User *user.User + // Service is the prefix to prepend to the description of the keys in + // user keyrings. Not relevant for filesystem keyrings. + Service string + // UseFsKeyringForV1Policies is true if keys for v1 encryption policies + // should be put in the filesystem's keyring (if supported) rather than + // in the user's keyring. Note that this makes AddEncryptionKey and + // RemoveEncryptionKey require root privileges. + UseFsKeyringForV1Policies bool +} + +func shouldUseFsKeyring(descriptor string, options *Options) bool { + // For v1 encryption policy keys, use the filesystem keyring if + // use_fs_keyring_for_v1_policies is set in /etc/fscrypt.conf and the + // kernel supports it. + if len(descriptor) == hex.EncodedLen(unix.FSCRYPT_KEY_DESCRIPTOR_SIZE) { + return options.UseFsKeyringForV1Policies && isFsKeyringSupported(options.Mount) + } + // For v2 encryption policy keys, always use the filesystem keyring; the + // kernel doesn't support any other way. + return true +} + +// AddEncryptionKey adds an encryption policy key to a kernel keyring. It uses +// either the filesystem keyring for the target Mount or the user keyring for +// the target User. +func AddEncryptionKey(key *crypto.Key, descriptor string, options *Options) error { + if err := util.CheckValidLength(metadata.PolicyKeyLen, key.Len()); err != nil { + return errors.Wrap(err, "policy key") + } + if shouldUseFsKeyring(descriptor, options) { + return fsAddEncryptionKey(key, descriptor, options.Mount, options.User) + } + return userAddKey(key, options.Service+descriptor, options.User) +} + +// RemoveEncryptionKey removes an encryption policy key from a kernel keyring. +// It uses either the filesystem keyring for the target Mount or the user +// keyring for the target User. +func RemoveEncryptionKey(descriptor string, options *Options, allUsers bool) error { + if shouldUseFsKeyring(descriptor, options) { + user := options.User + if allUsers { + user = nil + } + return fsRemoveEncryptionKey(descriptor, options.Mount, user) + } + return userRemoveKey(options.Service+descriptor, options.User) +} + +// KeyStatus is an enum that represents the status of a key in a kernel keyring. +type KeyStatus int + +// The possible values of KeyStatus. +const ( + KeyStatusUnknown = 0 + iota + KeyAbsent + KeyAbsentButFilesBusy + KeyPresent + KeyPresentButOnlyOtherUsers +) + +func (status KeyStatus) String() string { + switch status { + case KeyStatusUnknown: + return "Unknown" + case KeyAbsent: + return "Absent" + case KeyAbsentButFilesBusy: + return "AbsentButFilesBusy" + case KeyPresent: + return "Present" + case KeyPresentButOnlyOtherUsers: + return "PresentButOnlyOtherUsers" + default: + return strconv.Itoa(int(status)) + } +} + +// GetEncryptionKeyStatus gets the status of an encryption policy key in a +// kernel keyring. It uses either the filesystem keyring for the target Mount +// or the user keyring for the target User. +func GetEncryptionKeyStatus(descriptor string, options *Options) (KeyStatus, error) { + if shouldUseFsKeyring(descriptor, options) { + return fsGetEncryptionKeyStatus(descriptor, options.Mount, options.User) + } + _, err := userFindKey(options.Service+descriptor, options.User) + if err != nil { + return KeyAbsent, nil + } + return KeyPresent, nil +} diff --git a/keyring/keyring_test.go b/keyring/keyring_test.go new file mode 100644 index 0000000..8912556 --- /dev/null +++ b/keyring/keyring_test.go @@ -0,0 +1,350 @@ +/* + * keyring_test.go - tests for the keyring package + * + * Copyright 2017 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may not + * use this file except in compliance with the License. You may obtain a copy of + * the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations under + * the License. + */ + +package keyring + +import ( + "os/user" + "strconv" + "testing" + + "golang.org/x/sys/unix" + + "github.com/google/fscrypt/crypto" + "github.com/google/fscrypt/filesystem" + "github.com/google/fscrypt/metadata" + "github.com/google/fscrypt/util" +) + +// Reader that always returns the same byte +type ConstReader byte + +func (r ConstReader) Read(b []byte) (n int, err error) { + for i := range b { + b[i] = byte(r) + } + return len(b), nil +} + +// Makes a key of the same repeating byte +func makeKey(b byte, n int) (*crypto.Key, error) { + return crypto.NewFixedLengthKeyFromReader(ConstReader(b), n) +} + +var ( + defaultService = unix.FSCRYPT_KEY_DESC_PREFIX + testUser, _ = util.EffectiveUser() + fakeValidPolicyKey, _ = makeKey(42, metadata.PolicyKeyLen) + fakeInvalidPolicyKey, _ = makeKey(42, metadata.PolicyKeyLen-1) + fakeV1Descriptor = "0123456789abcdef" + fakeV2Descriptor, _ = crypto.ComputeKeyDescriptor(fakeValidPolicyKey, 2) +) + +func assertKeyStatus(t *testing.T, descriptor string, options *Options, + expectedStatus KeyStatus) { + status, err := GetEncryptionKeyStatus(descriptor, options) + if err != nil { + t.Error(err) + } + if status != expectedStatus { + t.Errorf("Expected key status %v but got key status %v", expectedStatus, status) + } +} + +// getTestMount retrieves the Mount for a test filesystem, or skips the test if +// no test filesystem is available. +func getTestMount(t *testing.T) *filesystem.Mount { + root, err := util.TestRoot() + if err != nil { + t.Skip(err) + } + mount, err := filesystem.GetMount(root) + if err != nil { + t.Skip(err) + } + return mount +} + +// getTestMountV2 is like getTestMount, but it also checks that the +// filesystem keyring and v2 encryption policies are supported. +func getTestMountV2(t *testing.T) *filesystem.Mount { + mount := getTestMount(t) + if !isFsKeyringSupported(mount) { + t.Skip("No support for fs keyring, skipping test.") + } + return mount +} + +func requireRoot(t *testing.T) { + if !util.IsUserRoot() { + t.Skip("Not root, skipping test.") + } +} + +// getNonRootUsers checks for root permission, then returns the users for uids +// 1000...1000+count-1. If this fails, the test is skipped. +func getNonRootUsers(t *testing.T, count int) []*user.User { + requireRoot(t) + users := make([]*user.User, count) + for i := 0; i < count; i++ { + uid := 1000 + i + user, err := user.LookupId(strconv.Itoa(uid)) + if err != nil { + t.Skip(err) + } + users[i] = user + } + return users +} + +func getOptionsForFsKeyringUsers(t *testing.T, numNonRootUsers int) (rootOptions *Options, userOptions []*Options) { + mount := getTestMountV2(t) + nonRootUsers := getNonRootUsers(t, numNonRootUsers) + rootOptions = &Options{ + Mount: mount, + User: testUser, + } + userOptions = make([]*Options, numNonRootUsers) + for i := 0; i < numNonRootUsers; i++ { + userOptions[i] = &Options{ + Mount: mount, + User: nonRootUsers[i], + } + } + return +} + +// testAddAndRemoveKey does the common tests for adding+removing keys that are +// run in multiple configurations (v1 policies with user keyring, v1 policies +// with fs keyring, and v2 policies with fs keyring). +func testAddAndRemoveKey(t *testing.T, descriptor string, options *Options) { + + // Basic add, get status, and remove + if err := AddEncryptionKey(fakeValidPolicyKey, descriptor, options); err != nil { + t.Error(err) + } + assertKeyStatus(t, descriptor, options, KeyPresent) + if err := RemoveEncryptionKey(descriptor, options, false); err != nil { + t.Error(err) + } + assertKeyStatus(t, descriptor, options, KeyAbsent) + err := RemoveEncryptionKey(descriptor, options, false) + if err != ErrKeyNotPresent { + t.Error(err) + } + + // Adding a key twice should succeed + if err := AddEncryptionKey(fakeValidPolicyKey, descriptor, options); err != nil { + t.Error(err) + } + if err := AddEncryptionKey(fakeValidPolicyKey, descriptor, options); err != nil { + t.Error("AddEncryptionKey should not fail if key already exists") + } + RemoveEncryptionKey(descriptor, options, false) + assertKeyStatus(t, descriptor, options, KeyAbsent) + + // Adding a key with wrong length should fail + if err := AddEncryptionKey(fakeInvalidPolicyKey, descriptor, options); err == nil { + RemoveEncryptionKey(descriptor, options, false) + t.Error("AddEncryptionKey should fail with wrong-length key") + } + assertKeyStatus(t, descriptor, options, KeyAbsent) +} + +func TestUserKeyringDefaultService(t *testing.T) { + options := &Options{ + User: testUser, + Service: defaultService, + UseFsKeyringForV1Policies: false, + } + testAddAndRemoveKey(t, fakeV1Descriptor, options) +} + +func TestUserKeyringExt4Service(t *testing.T) { + options := &Options{ + User: testUser, + Service: "ext4:", + UseFsKeyringForV1Policies: false, + } + testAddAndRemoveKey(t, fakeV1Descriptor, options) +} + +func TestUserKeyringF2fsService(t *testing.T) { + options := &Options{ + User: testUser, + Service: "f2fs:", + UseFsKeyringForV1Policies: false, + } + testAddAndRemoveKey(t, fakeV1Descriptor, options) +} + +func TestFsKeyringV1PolicyKey(t *testing.T) { + requireRoot(t) + mount := getTestMountV2(t) + options := &Options{ + Mount: mount, + User: testUser, + UseFsKeyringForV1Policies: true, + } + testAddAndRemoveKey(t, fakeV1Descriptor, options) +} + +func TestV2PolicyKey(t *testing.T) { + mount := getTestMountV2(t) + options := &Options{ + Mount: mount, + User: testUser, + } + testAddAndRemoveKey(t, fakeV2Descriptor, options) +} + +func TestV2PolicyKeyCannotBeRemovedByAnotherUser(t *testing.T) { + rootOptions, userOptions := getOptionsForFsKeyringUsers(t, 2) + user1Options := userOptions[0] + user2Options := userOptions[1] + + // Add key as non-root user. + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, user1Options); err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresentButOnlyOtherUsers) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + + // Key shouldn't be removable by another user, even root. + err := RemoveEncryptionKey(fakeV2Descriptor, user2Options, false) + if err != ErrKeyAddedByOtherUsers { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresentButOnlyOtherUsers) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + err = RemoveEncryptionKey(fakeV2Descriptor, rootOptions, false) + if err != ErrKeyAddedByOtherUsers { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresentButOnlyOtherUsers) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + + if err := RemoveEncryptionKey(fakeV2Descriptor, user1Options, false); err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyAbsent) +} + +func TestV2PolicyKeyMultipleUsers(t *testing.T) { + rootOptions, userOptions := getOptionsForFsKeyringUsers(t, 2) + user1Options := userOptions[0] + user2Options := userOptions[1] + + // Add key as two non-root users. + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, user1Options); err != nil { + t.Error(err) + } + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, user2Options); err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + + // Remove key as one user. + err := RemoveEncryptionKey(fakeV2Descriptor, user1Options, false) + if err != ErrKeyAddedByOtherUsers { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresentButOnlyOtherUsers) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + + // Remove key as the other user. + err = RemoveEncryptionKey(fakeV2Descriptor, user2Options, false) + if err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyAbsent) +} + +func TestV2PolicyKeyWrongDescriptor(t *testing.T) { + mount := getTestMountV2(t) + options := &Options{ + Mount: mount, + User: testUser, + } + // one wrong but valid hex, and one not valid hex + wrongV2Descriptors := []string{"abcdabcdabcdabcdabcdabcdabcdabcd", "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"} + + for _, desc := range wrongV2Descriptors { + if err := AddEncryptionKey(fakeValidPolicyKey, desc, options); err == nil { + RemoveEncryptionKey(desc, options, false) + t.Error("For v2 policy keys, AddEncryptionKey should fail if the descriptor is wrong") + } + } +} + +func TestV2PolicyKeyBadMount(t *testing.T) { + options := &Options{ + Mount: &filesystem.Mount{Path: "/NONEXISTENT_MOUNT"}, + User: testUser, + } + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, options); err == nil { + RemoveEncryptionKey(fakeV2Descriptor, options, false) + t.Error("AddEncryptionKey should have failed with bad mount!") + } + if err := RemoveEncryptionKey(fakeV2Descriptor, options, false); err == nil { + t.Error("RemoveEncryptionKey should have failed with bad mount!") + } + status, err := GetEncryptionKeyStatus(fakeV2Descriptor, options) + if err == nil { + t.Error("GetEncryptionKeyStatus should have failed with bad mount!") + } + if status != KeyStatusUnknown { + t.Error("GetEncryptionKeyStatus should have returned unknown status!") + } +} + +func TestV2PolicyKeyRemoveForAllUsers(t *testing.T) { + rootOptions, userOptions := getOptionsForFsKeyringUsers(t, 2) + user1Options := userOptions[0] + user2Options := userOptions[1] + + // Add key as two non-root users. + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, user1Options); err != nil { + t.Error(err) + } + if err := AddEncryptionKey(fakeValidPolicyKey, fakeV2Descriptor, user2Options); err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyPresent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyPresentButOnlyOtherUsers) + + // Remove key for all users as root. + err := RemoveEncryptionKey(fakeV2Descriptor, rootOptions, true) + if err != nil { + t.Error(err) + } + assertKeyStatus(t, fakeV2Descriptor, user1Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, user2Options, KeyAbsent) + assertKeyStatus(t, fakeV2Descriptor, rootOptions, KeyAbsent) +} diff --git a/security/keyring.go b/keyring/user_keyring.go index 3236775..71f519d 100644 --- a/security/keyring.go +++ b/keyring/user_keyring.go @@ -1,5 +1,6 @@ /* - * keyring.go - Handles inserting/removing into user keyrings. + * user_keyring.go - Add/remove encryption policy keys to/from user keyrings. + * This is the deprecated mechanism; see fs_keyring.go for the new mechanism. * * Copyright 2017 Google Inc. * Author: Joe Richey (joerichey@google.com) @@ -17,62 +18,69 @@ * the License. */ -package security +package keyring import ( - "fmt" - "log" "os/user" "runtime" + "unsafe" "github.com/pkg/errors" "golang.org/x/sys/unix" + "fmt" + "log" + + "github.com/google/fscrypt/crypto" + "github.com/google/fscrypt/security" "github.com/google/fscrypt/util" ) // KeyType is always logon as required by filesystem encryption. const KeyType = "logon" -// Keyring related error values -var ( - ErrKeySearch = errors.New("could not find key with descriptor") - ErrKeyRemove = util.SystemError("could not remove key from the keyring") - ErrKeyInsert = util.SystemError("could not insert key into the keyring") - ErrSessionUserKeying = errors.New("user keyring not linked into session keyring") - ErrAccessUserKeyring = errors.New("could not access user keyring") - ErrLinkUserKeyring = util.SystemError("could not link user keyring into root keyring") -) - -// FindKey tries to locate a key in the kernel keyring with the provided -// description. The key ID is returned if we can find the key. An error is -// returned if the key does not exist. -func FindKey(description string, targetUser *user.User) (int, error) { +// userAddKey puts the provided policy key into the user keyring for the +// specified user with the provided description, and type logon. +func userAddKey(key *crypto.Key, description string, targetUser *user.User) error { runtime.LockOSThread() // ensure target user keyring remains possessed in thread keyring defer runtime.UnlockOSThread() - keyringID, err := UserKeyringID(targetUser, false) + // Create our payload (containing an FscryptKey) + payload, err := crypto.NewBlankKey(int(unsafe.Sizeof(unix.FscryptKey{}))) if err != nil { - return 0, err + return err } + defer payload.Wipe() - keyID, err := unix.KeyctlSearch(keyringID, KeyType, description, 0) - log.Printf("KeyctlSearch(%d, %s, %s) = %d, %v", keyringID, KeyType, description, keyID, err) + // Cast the payload to an FscryptKey so we can initialize the fields. + fscryptKey := (*unix.FscryptKey)(payload.UnsafePtr()) + // Mode is ignored by the kernel + fscryptKey.Mode = 0 + fscryptKey.Size = uint32(key.Len()) + copy(fscryptKey.Raw[:], key.Data()) + + keyringID, err := UserKeyringID(targetUser, true) if err != nil { - return 0, errors.Wrap(ErrKeySearch, err.Error()) + return err } - return keyID, err + keyID, err := unix.AddKey(KeyType, description, payload.Data(), keyringID) + log.Printf("KeyctlAddKey(%s, %s, <data>, %d) = %d, %v", + KeyType, description, keyringID, keyID, err) + if err != nil { + return errors.Wrap(ErrKeyAdd, err.Error()) + } + return nil } -// RemoveKey tries to remove a policy key from the kernel keyring with the +// userRemoveKey tries to remove a policy key from the user keyring with the // provided description. An error is returned if the key does not exist. -func RemoveKey(description string, targetUser *user.User) error { +func userRemoveKey(description string, targetUser *user.User) error { runtime.LockOSThread() // ensure target user keyring remains possessed in thread keyring defer runtime.UnlockOSThread() - keyID, err := FindKey(description, targetUser) + keyID, err := userFindKey(description, targetUser) if err != nil { - return err + return ErrKeyNotPresent } // We use KEYCTL_INVALIDATE instead of KEYCTL_REVOKE because @@ -85,24 +93,24 @@ func RemoveKey(description string, targetUser *user.User) error { return nil } -// InsertKey puts the provided data into the kernel keyring with the provided -// description. -func InsertKey(data []byte, description string, targetUser *user.User) error { +// userFindKey tries to locate a key in the user keyring with the provided +// description. The key ID is returned if we can find the key. An error is +// returned if the key does not exist. +func userFindKey(description string, targetUser *user.User) (int, error) { runtime.LockOSThread() // ensure target user keyring remains possessed in thread keyring defer runtime.UnlockOSThread() - keyringID, err := UserKeyringID(targetUser, true) + keyringID, err := UserKeyringID(targetUser, false) if err != nil { - return err + return 0, err } - keyID, err := unix.AddKey(KeyType, description, data, keyringID) - log.Printf("KeyctlAddKey(%s, %s, <data>, %d) = %d, %v", - KeyType, description, keyringID, keyID, err) + keyID, err := unix.KeyctlSearch(keyringID, KeyType, description, 0) + log.Printf("KeyctlSearch(%d, %s, %s) = %d, %v", keyringID, KeyType, description, keyID, err) if err != nil { - return errors.Wrap(ErrKeyInsert, err.Error()) + return 0, errors.Wrap(ErrKeySearch, err.Error()) } - return nil + return keyID, err } // UserKeyringID returns the key id of the target user's user keyring. We also @@ -155,13 +163,13 @@ func userKeyringIDLookup(uid int) (keyringID int, err error) { // - Keyring linking permissions use the euid // So we have to change both the ruid and euid to make this work, // setting the suid to 0 so that we can later switch back. - ruid, euid, suid := getUids() + ruid, euid, suid := security.GetUids() if ruid != uid || euid != uid { - if err = setUids(uid, uid, 0); err != nil { + if err = security.SetUids(uid, uid, 0); err != nil { return } defer func() { - resetErr := setUids(ruid, euid, suid) + resetErr := security.SetUids(ruid, euid, suid) if resetErr != nil { err = resetErr } diff --git a/metadata/checks.go b/metadata/checks.go index 4fe4531..84fd208 100644 --- a/metadata/checks.go +++ b/metadata/checks.go @@ -119,7 +119,7 @@ func (p *ProtectorData) CheckValidity() error { if err := p.WrappedKey.CheckValidity(); err != nil { return errors.Wrap(err, "wrapped protector key") } - if err := util.CheckValidLength(DescriptorLen, len(p.ProtectorDescriptor)); err != nil { + if err := util.CheckValidLength(ProtectorDescriptorLen, len(p.ProtectorDescriptor)); err != nil { return errors.Wrap(err, "protector descriptor") } @@ -138,7 +138,17 @@ func (e *EncryptionOptions) CheckValidity() error { if err := e.Contents.CheckValidity(); err != nil { return errors.Wrap(err, "contents encryption mode") } - return errors.Wrap(e.Filenames.CheckValidity(), "filenames encryption mode") + if err := e.Filenames.CheckValidity(); err != nil { + return errors.Wrap(err, "filenames encryption mode") + } + // If PolicyVersion is unset, treat it as 1. + if e.PolicyVersion == 0 { + e.PolicyVersion = 1 + } + if e.PolicyVersion != 1 && e.PolicyVersion != 2 { + return errors.Errorf("policy version of %d is invalid", e.PolicyVersion) + } + return nil } // CheckValidity ensures the fields are valid and have the correct lengths. @@ -152,7 +162,7 @@ func (w *WrappedPolicyKey) CheckValidity() error { if err := util.CheckValidLength(PolicyKeyLen, len(w.WrappedKey.EncryptedKey)); err != nil { return errors.Wrap(err, "encrypted key") } - err := util.CheckValidLength(DescriptorLen, len(w.ProtectorDescriptor)) + err := util.CheckValidLength(ProtectorDescriptorLen, len(w.ProtectorDescriptor)) return errors.Wrap(err, "wrapping protector descriptor") } @@ -167,11 +177,26 @@ func (p *PolicyData) CheckValidity() error { return errors.Wrapf(err, "policy key slot %d", i) } } - if err := util.CheckValidLength(DescriptorLen, len(p.KeyDescriptor)); err != nil { + + if err := p.Options.CheckValidity(); err != nil { + return errors.Wrap(err, "policy options") + } + + var expectedLen int + switch p.Options.PolicyVersion { + case 1: + expectedLen = PolicyDescriptorLenV1 + case 2: + expectedLen = PolicyDescriptorLenV2 + default: + return errors.Errorf("policy version of %d is invalid", p.Options.PolicyVersion) + } + + if err := util.CheckValidLength(expectedLen, len(p.KeyDescriptor)); err != nil { return errors.Wrap(err, "policy key descriptor") } - return errors.Wrap(p.Options.CheckValidity(), "policy options") + return nil } // CheckValidity ensures the Config has all the necessary info for its Source. diff --git a/metadata/config_test.go b/metadata/config_test.go index d184a87..83c1eb0 100644 --- a/metadata/config_test.go +++ b/metadata/config_test.go @@ -48,8 +48,10 @@ var testConfigString = `{ "options": { "padding": "32", "contents": "AES_256_XTS", - "filenames": "AES_256_CTS" - } + "filenames": "AES_256_CTS", + "policy_version": "1" + }, + "use_fs_keyring_for_v1_policies": false } ` @@ -77,3 +79,41 @@ func TestRead(t *testing.T) { t.Errorf("did not match: %s", testConfig) } } + +// Makes sure we can parse a legacy config file that doesn't have the fields +// that were added later. +func TestOptionalFields(t *testing.T) { + contents := `{ + "source": "custom_passphrase", + "hash_costs": { + "time": "10", + "memory": "4096", + "parallelism": "8" + }, + "compatibility": "", + "options": { + "padding": "32", + "contents": "AES_256_XTS", + "filenames": "AES_256_CTS" + } + } + ` + buf := bytes.NewBufferString(contents) + cfg, err := ReadConfig(buf) + if err != nil { + t.Fatal(err) + } + if cfg.GetUseFsKeyringForV1Policies() { + t.Error("use_fs_keyring_for_v1_policies should be false, but was true") + } + if cfg.Options.PolicyVersion != 0 { + t.Errorf("policy version should be 0, but was %d", cfg.Options.PolicyVersion) + } + if err = cfg.CheckValidity(); err != nil { + t.Error(err) + } + // CheckValidity() should change an unset policy version to 1. + if cfg.Options.PolicyVersion != 1 { + t.Errorf("policy version should be 1 now, but was %d", cfg.Options.PolicyVersion) + } +} diff --git a/metadata/constants.go b/metadata/constants.go index 8855ae3..fa6b8a7 100644 --- a/metadata/constants.go +++ b/metadata/constants.go @@ -27,8 +27,12 @@ import ( // Lengths for our keys, buffers, and strings used in fscrypt. const ( - // DescriptorLen is the length of all Protector and Policy descriptors. - DescriptorLen = 2 * unix.FSCRYPT_KEY_DESCRIPTOR_SIZE + // Length of policy descriptor (in hex chars) for v1 encryption policies + PolicyDescriptorLenV1 = 2 * unix.FSCRYPT_KEY_DESCRIPTOR_SIZE + // Length of protector descriptor (in hex chars) + ProtectorDescriptorLen = PolicyDescriptorLenV1 + // Length of policy descriptor (in hex chars) for v2 encryption policies + PolicyDescriptorLenV2 = 2 * unix.FSCRYPT_KEY_IDENTIFIER_SIZE // We always use 256-bit keys internally (compared to 512-bit policy keys). InternalKeyLen = 32 IVLen = 16 @@ -40,11 +44,13 @@ const ( ) var ( - // DefaultOptions use the supported encryption modes and max padding. + // DefaultOptions use the supported encryption modes, max padding, and + // policy version 1. DefaultOptions = &EncryptionOptions{ - Padding: 32, - Contents: EncryptionOptions_AES_256_XTS, - Filenames: EncryptionOptions_AES_256_CTS, + Padding: 32, + Contents: EncryptionOptions_AES_256_XTS, + Filenames: EncryptionOptions_AES_256_CTS, + PolicyVersion: 1, } // DefaultSource is the source we use if none is specified. DefaultSource = SourceType_custom_passphrase diff --git a/metadata/metadata.pb.go b/metadata/metadata.pb.go index bd3ee2a..e6067f9 100644 --- a/metadata/metadata.pb.go +++ b/metadata/metadata.pb.go @@ -45,7 +45,7 @@ func (x SourceType) String() string { return proto.EnumName(SourceType_name, int32(x)) } func (SourceType) EnumDescriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{0} + return fileDescriptor_metadata_0a34c99c54153da9, []int{0} } // Type of encryption; should match declarations of unix.FSCRYPT_MODE @@ -87,7 +87,7 @@ func (x EncryptionOptions_Mode) String() string { return proto.EnumName(EncryptionOptions_Mode_name, int32(x)) } func (EncryptionOptions_Mode) EnumDescriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{3, 0} + return fileDescriptor_metadata_0a34c99c54153da9, []int{3, 0} } // Cost parameters to be used in our hashing functions. @@ -104,7 +104,7 @@ func (m *HashingCosts) Reset() { *m = HashingCosts{} } func (m *HashingCosts) String() string { return proto.CompactTextString(m) } func (*HashingCosts) ProtoMessage() {} func (*HashingCosts) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{0} + return fileDescriptor_metadata_0a34c99c54153da9, []int{0} } func (m *HashingCosts) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_HashingCosts.Unmarshal(m, b) @@ -159,7 +159,7 @@ func (m *WrappedKeyData) Reset() { *m = WrappedKeyData{} } func (m *WrappedKeyData) String() string { return proto.CompactTextString(m) } func (*WrappedKeyData) ProtoMessage() {} func (*WrappedKeyData) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{1} + return fileDescriptor_metadata_0a34c99c54153da9, []int{1} } func (m *WrappedKeyData) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_WrappedKeyData.Unmarshal(m, b) @@ -219,7 +219,7 @@ func (m *ProtectorData) Reset() { *m = ProtectorData{} } func (m *ProtectorData) String() string { return proto.CompactTextString(m) } func (*ProtectorData) ProtoMessage() {} func (*ProtectorData) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{2} + return fileDescriptor_metadata_0a34c99c54153da9, []int{2} } func (m *ProtectorData) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_ProtectorData.Unmarshal(m, b) @@ -293,6 +293,7 @@ type EncryptionOptions struct { Padding int64 `protobuf:"varint,1,opt,name=padding,proto3" json:"padding,omitempty"` Contents EncryptionOptions_Mode `protobuf:"varint,2,opt,name=contents,proto3,enum=metadata.EncryptionOptions_Mode" json:"contents,omitempty"` Filenames EncryptionOptions_Mode `protobuf:"varint,3,opt,name=filenames,proto3,enum=metadata.EncryptionOptions_Mode" json:"filenames,omitempty"` + PolicyVersion int64 `protobuf:"varint,4,opt,name=policy_version,json=policyVersion,proto3" json:"policy_version,omitempty"` XXX_NoUnkeyedLiteral struct{} `json:"-"` XXX_unrecognized []byte `json:"-"` XXX_sizecache int32 `json:"-"` @@ -302,7 +303,7 @@ func (m *EncryptionOptions) Reset() { *m = EncryptionOptions{} } func (m *EncryptionOptions) String() string { return proto.CompactTextString(m) } func (*EncryptionOptions) ProtoMessage() {} func (*EncryptionOptions) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{3} + return fileDescriptor_metadata_0a34c99c54153da9, []int{3} } func (m *EncryptionOptions) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_EncryptionOptions.Unmarshal(m, b) @@ -343,6 +344,13 @@ func (m *EncryptionOptions) GetFilenames() EncryptionOptions_Mode { return EncryptionOptions_default } +func (m *EncryptionOptions) GetPolicyVersion() int64 { + if m != nil { + return m.PolicyVersion + } + return 0 +} + type WrappedPolicyKey struct { ProtectorDescriptor string `protobuf:"bytes,1,opt,name=protector_descriptor,json=protectorDescriptor,proto3" json:"protector_descriptor,omitempty"` WrappedKey *WrappedKeyData `protobuf:"bytes,2,opt,name=wrapped_key,json=wrappedKey,proto3" json:"wrapped_key,omitempty"` @@ -355,7 +363,7 @@ func (m *WrappedPolicyKey) Reset() { *m = WrappedPolicyKey{} } func (m *WrappedPolicyKey) String() string { return proto.CompactTextString(m) } func (*WrappedPolicyKey) ProtoMessage() {} func (*WrappedPolicyKey) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{4} + return fileDescriptor_metadata_0a34c99c54153da9, []int{4} } func (m *WrappedPolicyKey) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_WrappedPolicyKey.Unmarshal(m, b) @@ -403,7 +411,7 @@ func (m *PolicyData) Reset() { *m = PolicyData{} } func (m *PolicyData) String() string { return proto.CompactTextString(m) } func (*PolicyData) ProtoMessage() {} func (*PolicyData) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{5} + return fileDescriptor_metadata_0a34c99c54153da9, []int{5} } func (m *PolicyData) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_PolicyData.Unmarshal(m, b) @@ -446,20 +454,21 @@ func (m *PolicyData) GetWrappedPolicyKeys() []*WrappedPolicyKey { // Data stored in the config file type Config struct { - Source SourceType `protobuf:"varint,1,opt,name=source,proto3,enum=metadata.SourceType" json:"source,omitempty"` - HashCosts *HashingCosts `protobuf:"bytes,2,opt,name=hash_costs,json=hashCosts,proto3" json:"hash_costs,omitempty"` - Compatibility string `protobuf:"bytes,3,opt,name=compatibility,proto3" json:"compatibility,omitempty"` - Options *EncryptionOptions `protobuf:"bytes,4,opt,name=options,proto3" json:"options,omitempty"` - XXX_NoUnkeyedLiteral struct{} `json:"-"` - XXX_unrecognized []byte `json:"-"` - XXX_sizecache int32 `json:"-"` + Source SourceType `protobuf:"varint,1,opt,name=source,proto3,enum=metadata.SourceType" json:"source,omitempty"` + HashCosts *HashingCosts `protobuf:"bytes,2,opt,name=hash_costs,json=hashCosts,proto3" json:"hash_costs,omitempty"` + Compatibility string `protobuf:"bytes,3,opt,name=compatibility,proto3" json:"compatibility,omitempty"` + Options *EncryptionOptions `protobuf:"bytes,4,opt,name=options,proto3" json:"options,omitempty"` + UseFsKeyringForV1Policies bool `protobuf:"varint,5,opt,name=use_fs_keyring_for_v1_policies,json=useFsKeyringForV1Policies,proto3" json:"use_fs_keyring_for_v1_policies,omitempty"` + XXX_NoUnkeyedLiteral struct{} `json:"-"` + XXX_unrecognized []byte `json:"-"` + XXX_sizecache int32 `json:"-"` } func (m *Config) Reset() { *m = Config{} } func (m *Config) String() string { return proto.CompactTextString(m) } func (*Config) ProtoMessage() {} func (*Config) Descriptor() ([]byte, []int) { - return fileDescriptor_metadata_fa046c95c3cd6aa1, []int{6} + return fileDescriptor_metadata_0a34c99c54153da9, []int{6} } func (m *Config) XXX_Unmarshal(b []byte) error { return xxx_messageInfo_Config.Unmarshal(m, b) @@ -507,6 +516,13 @@ func (m *Config) GetOptions() *EncryptionOptions { return nil } +func (m *Config) GetUseFsKeyringForV1Policies() bool { + if m != nil { + return m.UseFsKeyringForV1Policies + } + return false +} + func init() { proto.RegisterType((*HashingCosts)(nil), "metadata.HashingCosts") proto.RegisterType((*WrappedKeyData)(nil), "metadata.WrappedKeyData") @@ -519,49 +535,53 @@ func init() { proto.RegisterEnum("metadata.EncryptionOptions_Mode", EncryptionOptions_Mode_name, EncryptionOptions_Mode_value) } -func init() { proto.RegisterFile("metadata/metadata.proto", fileDescriptor_metadata_fa046c95c3cd6aa1) } - -var fileDescriptor_metadata_fa046c95c3cd6aa1 = []byte{ - // 656 bytes of a gzipped FileDescriptorProto - 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x9c, 0x94, 0xef, 0x6a, 0xdb, 0x3c, - 0x14, 0xc6, 0x5f, 0xdb, 0x69, 0xd2, 0x9c, 0xfc, 0x79, 0x5d, 0xb5, 0x6f, 0x5f, 0xb3, 0x7d, 0x09, - 0xde, 0x06, 0x65, 0x94, 0x8e, 0x66, 0x74, 0x6c, 0x30, 0x06, 0x5d, 0x5a, 0xb6, 0xae, 0x94, 0x75, - 0x4a, 0xe8, 0x36, 0x18, 0x04, 0xd5, 0x56, 0x1b, 0x51, 0xdb, 0x12, 0x96, 0x42, 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0xc4, 0x23, 0x8e, 0x05, 0xb1, 0x0c, 0xf4, 0x1f, 0xac, 0x7b, 0x13, 0x21, 0xd9, + 0x8a, 0x6c, 0xaa, 0x73, 0x1c, 0x4f, 0x55, 0x15, 0x56, 0xee, 0xa2, 0xa0, 0xff, 0xee, 0xcf, 0xfe, + 0x04, 0x00, 0x00, 0xff, 0xff, 0xfc, 0x97, 0x5e, 0xdf, 0xf8, 0x05, 0x00, 0x00, } diff --git a/metadata/metadata.proto b/metadata/metadata.proto index 735181e..81b3bf9 100644 --- a/metadata/metadata.proto +++ b/metadata/metadata.proto @@ -77,6 +77,8 @@ message EncryptionOptions { Mode contents = 2; Mode filenames = 3; + + int64 policy_version = 4; } message WrappedPolicyKey { @@ -97,4 +99,5 @@ message Config { HashingCosts hash_costs = 2; string compatibility = 3; EncryptionOptions options = 4; + bool use_fs_keyring_for_v1_policies = 5; } diff --git a/metadata/policy.go b/metadata/policy.go index f9af44a..b95bf42 100644 --- a/metadata/policy.go +++ b/metadata/policy.go @@ -42,14 +42,14 @@ var ( ErrBadEncryptionOptions = util.SystemError("invalid encryption options provided") ) -// policyIoctl is a wrapper for the ioctl syscall. It passes the correct -// pointers and file descriptors to the IOCTL syscall. This function also takes -// some of the unclear errors returned by the syscall and translates then into -// more specific error strings. -func policyIoctl(file *os.File, request uintptr, policy *unix.FscryptPolicyV1) error { +// policyIoctl is a wrapper around the ioctls that get and set encryption +// policies: FS_IOC_GET_ENCRYPTION_POLICY, FS_IOC_GET_ENCRYPTION_POLICY_EX, and +// FS_IOC_SET_ENCRYPTION_POLICY. It translates the raw errno values into more +// descriptive errors. +func policyIoctl(file *os.File, request uintptr, arg unsafe.Pointer) error { // The returned errno value can sometimes give strange errors, so we // return encryption specific errors. - _, _, errno := unix.Syscall(unix.SYS_IOCTL, file.Fd(), request, uintptr(unsafe.Pointer(policy))) + _, _, errno := unix.Syscall(unix.SYS_IOCTL, file.Fd(), request, uintptr(arg)) switch errno { case 0: return nil @@ -61,7 +61,6 @@ func policyIoctl(file *os.File, request uintptr, policy *unix.FscryptPolicyV1) e // ENOENT was returned instead of ENODATA on some filesystems before v4.11. return ErrNotEncrypted case unix.EEXIST: - // EINVAL was returned instead of EEXIST on some filesystems before v4.11. return ErrEncrypted default: return errno @@ -75,6 +74,42 @@ var ( unix.FSCRYPT_POLICY_FLAGS_PAD_16, unix.FSCRYPT_POLICY_FLAGS_PAD_32} ) +// flagsToPadding returns the amount of padding specified in the policy flags. +func flagsToPadding(flags uint8) int64 { + paddingFlag := int64(flags & unix.FS_POLICY_FLAGS_PAD_MASK) + + // This lookup should always succeed + padding, ok := util.Lookup(paddingFlag, flagsArray, paddingArray) + if !ok { + log.Panicf("padding flag of %x not found", paddingFlag) + } + return padding +} + +func buildV1PolicyData(policy *unix.FscryptPolicyV1) *PolicyData { + return &PolicyData{ + KeyDescriptor: hex.EncodeToString(policy.Master_key_descriptor[:]), + Options: &EncryptionOptions{ + Padding: flagsToPadding(policy.Flags), + Contents: EncryptionOptions_Mode(policy.Contents_encryption_mode), + Filenames: EncryptionOptions_Mode(policy.Filenames_encryption_mode), + PolicyVersion: 1, + }, + } +} + +func buildV2PolicyData(policy *unix.FscryptPolicyV2) *PolicyData { + return &PolicyData{ + KeyDescriptor: hex.EncodeToString(policy.Master_key_identifier[:]), + Options: &EncryptionOptions{ + Padding: flagsToPadding(policy.Flags), + Contents: EncryptionOptions_Mode(policy.Contents_encryption_mode), + Filenames: EncryptionOptions_Mode(policy.Filenames_encryption_mode), + PolicyVersion: 2, + }, + } +} + // GetPolicy returns the Policy data for the given directory or file (includes // the KeyDescriptor and the encryption options). Returns an error if the // path is not encrypted or the policy couldn't be retrieved. @@ -85,28 +120,36 @@ func GetPolicy(path string) (*PolicyData, error) { } defer file.Close() - var policy unix.FscryptPolicyV1 - if err = policyIoctl(file, unix.FS_IOC_GET_ENCRYPTION_POLICY, &policy); err != nil { + // First try the new version of the ioctl. This works for both v1 and v2 policies. + var arg unix.FscryptGetPolicyExArg + arg.Size = uint64(unsafe.Sizeof(arg.Policy)) + policyPtr := util.Ptr(arg.Policy[:]) + err = policyIoctl(file, unix.FS_IOC_GET_ENCRYPTION_POLICY_EX, unsafe.Pointer(&arg)) + if err == ErrEncryptionNotSupported { + // Fall back to the old version of the ioctl. This works for v1 policies only. + err = policyIoctl(file, unix.FS_IOC_GET_ENCRYPTION_POLICY, policyPtr) + arg.Size = uint64(unsafe.Sizeof(unix.FscryptPolicyV1{})) + } + if err != nil { return nil, errors.Wrapf(err, "get encryption policy %s", path) } - - // Convert the padding flag into an amount of padding - paddingFlag := int64(policy.Flags & unix.FSCRYPT_POLICY_FLAGS_PAD_MASK) - - // This lookup should always succeed - padding, ok := util.Lookup(paddingFlag, flagsArray, paddingArray) - if !ok { - log.Panicf("padding flag of %x not found", paddingFlag) + switch arg.Policy[0] { // arg.policy.version + case unix.FSCRYPT_POLICY_V1: + if arg.Size != uint64(unsafe.Sizeof(unix.FscryptPolicyV1{})) { + // should never happen + return nil, errors.New("unexpected size for v1 policy") + } + return buildV1PolicyData((*unix.FscryptPolicyV1)(policyPtr)), nil + case unix.FSCRYPT_POLICY_V2: + if arg.Size != uint64(unsafe.Sizeof(unix.FscryptPolicyV2{})) { + // should never happen + return nil, errors.New("unexpected size for v2 policy") + } + return buildV2PolicyData((*unix.FscryptPolicyV2)(policyPtr)), nil + default: + return nil, errors.Errorf("unsupported encryption policy version [%d]", + arg.Policy[0]) } - - return &PolicyData{ - KeyDescriptor: hex.EncodeToString(policy.Master_key_descriptor[:]), - Options: &EncryptionOptions{ - Padding: padding, - Contents: EncryptionOptions_Mode(policy.Contents_encryption_mode), - Filenames: EncryptionOptions_Mode(policy.Filenames_encryption_mode), - }, - }, nil } // For improved performance, use the DIRECT_KEY flag when using ciphers that @@ -121,6 +164,52 @@ func shouldUseDirectKeyFlag(options *EncryptionOptions) bool { return options.Contents == EncryptionOptions_Adiantum } +func buildPolicyFlags(options *EncryptionOptions) uint8 { + // This lookup should always succeed (as policy is valid) + flags, ok := util.Lookup(options.Padding, paddingArray, flagsArray) + if !ok { + log.Panicf("padding of %d was not found", options.Padding) + } + if shouldUseDirectKeyFlag(options) { + flags |= unix.FSCRYPT_POLICY_FLAG_DIRECT_KEY + } + return uint8(flags) +} + +func setV1Policy(file *os.File, options *EncryptionOptions, descriptorBytes []byte) error { + policy := unix.FscryptPolicyV1{ + Version: unix.FSCRYPT_POLICY_V1, + Contents_encryption_mode: uint8(options.Contents), + Filenames_encryption_mode: uint8(options.Filenames), + Flags: uint8(buildPolicyFlags(options)), + } + + // The descriptor should always be the correct length (as policy is valid) + if len(descriptorBytes) != unix.FSCRYPT_KEY_DESCRIPTOR_SIZE { + log.Panic("wrong descriptor size for v1 policy") + } + copy(policy.Master_key_descriptor[:], descriptorBytes) + + return policyIoctl(file, unix.FS_IOC_SET_ENCRYPTION_POLICY, unsafe.Pointer(&policy)) +} + +func setV2Policy(file *os.File, options *EncryptionOptions, descriptorBytes []byte) error { + policy := unix.FscryptPolicyV2{ + Version: unix.FSCRYPT_POLICY_V2, + Contents_encryption_mode: uint8(options.Contents), + Filenames_encryption_mode: uint8(options.Filenames), + Flags: uint8(buildPolicyFlags(options)), + } + + // The descriptor should always be the correct length (as policy is valid) + if len(descriptorBytes) != unix.FSCRYPT_KEY_IDENTIFIER_SIZE { + log.Panic("wrong descriptor size for v2 policy") + } + copy(policy.Master_key_identifier[:], descriptorBytes) + + return policyIoctl(file, unix.FS_IOC_SET_ENCRYPTION_POLICY, unsafe.Pointer(&policy)) +} + // SetPolicy sets up the specified directory to be encrypted with the specified // policy. Returns an error if we cannot set the policy for any reason (not a // directory, invalid options or KeyDescriptor, etc). @@ -135,30 +224,21 @@ func SetPolicy(path string, data *PolicyData) error { return errors.Wrap(err, "invalid policy") } - // This lookup should always succeed (as policy is valid) - flags, ok := util.Lookup(data.Options.Padding, paddingArray, flagsArray) - if !ok { - log.Panicf("padding of %d was not found", data.Options.Padding) - } - descriptorBytes, err := hex.DecodeString(data.KeyDescriptor) if err != nil { - return errors.New("invalid descriptor: " + data.KeyDescriptor) - } - - if shouldUseDirectKeyFlag(data.Options) { - flags |= unix.FSCRYPT_POLICY_FLAG_DIRECT_KEY + return errors.New("invalid key descriptor: " + data.KeyDescriptor) } - policy := unix.FscryptPolicyV1{ - Version: unix.FSCRYPT_POLICY_V1, - Contents_encryption_mode: uint8(data.Options.Contents), - Filenames_encryption_mode: uint8(data.Options.Filenames), - Flags: uint8(flags), + switch data.Options.PolicyVersion { + case 1: + err = setV1Policy(file, data.Options, descriptorBytes) + case 2: + err = setV2Policy(file, data.Options, descriptorBytes) + default: + err = errors.Errorf("policy version of %d is invalid", data.Options.PolicyVersion) } - copy(policy.Master_key_descriptor[:], descriptorBytes) - if err = policyIoctl(file, unix.FS_IOC_SET_ENCRYPTION_POLICY, &policy); err == unix.EINVAL { + if err == unix.EINVAL { // Before kernel v4.11, many different errors all caused unix.EINVAL to be returned. // We try to disambiguate this error here. This disambiguation will not always give // the correct error due to a potential race condition on path. @@ -195,7 +275,7 @@ func CheckSupport(path string) error { Flags: math.MaxUint8, } - err = policyIoctl(file, unix.FS_IOC_SET_ENCRYPTION_POLICY, &badPolicy) + err = policyIoctl(file, unix.FS_IOC_SET_ENCRYPTION_POLICY, unsafe.Pointer(&badPolicy)) switch err { case nil: log.Panicf(`FS_IOC_SET_ENCRYPTION_POLICY succeeded when it should have failed. diff --git a/metadata/policy_test.go b/metadata/policy_test.go index ad9dd80..3c0704a 100644 --- a/metadata/policy_test.go +++ b/metadata/policy_test.go @@ -26,17 +26,30 @@ import ( "testing" "github.com/golang/protobuf/proto" + "golang.org/x/sys/unix" "github.com/google/fscrypt/util" ) -const goodDescriptor = "0123456789abcdef" +const goodV1Descriptor = "0123456789abcdef" -var goodPolicy = &PolicyData{ - KeyDescriptor: goodDescriptor, +var goodV1Policy = &PolicyData{ + KeyDescriptor: goodV1Descriptor, Options: DefaultOptions, } +var goodV2EncryptionOptions = &EncryptionOptions{ + Padding: 32, + Contents: EncryptionOptions_AES_256_XTS, + Filenames: EncryptionOptions_AES_256_CTS, + PolicyVersion: 2, +} + +var goodV2Policy = &PolicyData{ + KeyDescriptor: "0123456789abcdef0123456789abcdef", + Options: goodV2EncryptionOptions, +} + // Creates a temporary directory for testing. func createTestDirectory(t *testing.T) (directory string, err error) { baseDirectory, err := util.TestRoot() @@ -83,7 +96,7 @@ func TestSetPolicyEmptyDirectory(t *testing.T) { } defer os.RemoveAll(directory) - if err = SetPolicy(directory, goodPolicy); err != nil { + if err = SetPolicy(directory, goodV1Policy); err != nil { t.Error(err) } } @@ -96,7 +109,7 @@ func TestSetPolicyNonemptyDirectory(t *testing.T) { } defer os.RemoveAll(directory) - if err = SetPolicy(directory, goodPolicy); err == nil { + if err = SetPolicy(directory, goodV1Policy); err == nil { t.Error("should have failed to set policy on a nonempty directory") } } @@ -109,7 +122,7 @@ func TestSetPolicyFile(t *testing.T) { } defer os.RemoveAll(directory) - if err = SetPolicy(file, goodPolicy); err == nil { + if err = SetPolicy(file, goodV1Policy); err == nil { t.Error("should have failed to set policy on a file") } } @@ -141,15 +154,15 @@ func TestGetPolicyEmptyDirectory(t *testing.T) { defer os.RemoveAll(directory) var actualPolicy *PolicyData - if err = SetPolicy(directory, goodPolicy); err != nil { + if err = SetPolicy(directory, goodV1Policy); err != nil { t.Fatal(err) } if actualPolicy, err = GetPolicy(directory); err != nil { t.Fatal(err) } - if !proto.Equal(actualPolicy, goodPolicy) { - t.Errorf("policy %+v does not equal expected policy %+v", actualPolicy, goodPolicy) + if !proto.Equal(actualPolicy, goodV1Policy) { + t.Errorf("policy %+v does not equal expected policy %+v", actualPolicy, goodV1Policy) } } @@ -165,3 +178,35 @@ func TestGetPolicyUnencrypted(t *testing.T) { t.Error("should have failed to set policy on a file") } } + +func requireV2PolicySupport(t *testing.T, directory string) { + file, err := os.Open(directory) + if err != nil { + t.Fatal(err) + } + defer file.Close() + + err = policyIoctl(file, unix.FS_IOC_GET_ENCRYPTION_POLICY_EX, nil) + if err == ErrEncryptionNotSupported { + t.Skip("No support for v2 encryption policies, skipping test") + } +} + +// Tests that a non-root user cannot set a v2 encryption policy unless the key +// has been added. +func TestSetV2PolicyNoKey(t *testing.T) { + if util.IsUserRoot() { + t.Skip("This test cannot be run as root") + } + directory, err := createTestDirectory(t) + if err != nil { + t.Fatal(err) + } + defer os.RemoveAll(directory) + requireV2PolicySupport(t, directory) + + err = SetPolicy(directory, goodV2Policy) + if err == nil { + t.Error("shouldn't have been able to set v2 policy without key added") + } +} @@ -127,26 +127,31 @@ func (h *Handle) GetItem(i Item) (unsafe.Pointer, error) { return data, nil } -// StartAsPamUser sets the effective privileges to that of the PAM user, and -// configures the PAM user's keyrings to be properly linked. +// StartAsPamUser sets the effective privileges to that of the PAM user. func (h *Handle) StartAsPamUser() error { - if _, err := security.UserKeyringID(h.PamUser, true); err != nil { - log.Printf("Setting up keyrings in PAM: %v", err) - } userPrivs, err := security.UserPrivileges(h.PamUser) if err != nil { return err } - if h.origPrivs, err = security.ProcessPrivileges(); err != nil { + origPrivs, err := security.ProcessPrivileges() + if err != nil { + return err + } + if err = security.SetProcessPrivileges(userPrivs); err != nil { return err } - return security.SetProcessPrivileges(userPrivs) + h.origPrivs = origPrivs + return nil } // StopAsPamUser restores the original privileges that were running the // PAM module (this is usually root). func (h *Handle) StopAsPamUser() error { + if h.origPrivs == nil { + return nil + } err := security.SetProcessPrivileges(h.origPrivs) + h.origPrivs = nil if err != nil { log.Print(err) } diff --git a/pam_fscrypt/pam_fscrypt.go b/pam_fscrypt/pam_fscrypt.go index c7f9931..a7582cc 100644 --- a/pam_fscrypt/pam_fscrypt.go +++ b/pam_fscrypt/pam_fscrypt.go @@ -36,6 +36,7 @@ import ( "github.com/google/fscrypt/actions" "github.com/google/fscrypt/crypto" + "github.com/google/fscrypt/keyring" "github.com/google/fscrypt/pam" "github.com/google/fscrypt/security" ) @@ -81,6 +82,43 @@ func Authenticate(handle *pam.Handle, _ map[string]bool) error { return errors.Wrap(err, "could not set AUTHTOK data") } +func beginProvisioningOp(handle *pam.Handle, policy *actions.Policy) error { + if policy.NeedsRootToProvision() { + return handle.StopAsPamUser() + } + return nil +} + +func endProvisioningOp(handle *pam.Handle, policy *actions.Policy) error { + if policy.NeedsRootToProvision() { + return handle.StartAsPamUser() + } + return nil +} + +// Set up the PAM user's keyring if needed by any encryption policies. +func setupUserKeyringIfNeeded(handle *pam.Handle, policies []*actions.Policy) error { + needed := false + for _, policy := range policies { + if policy.NeedsUserKeyring() { + needed = true + break + } + } + if !needed { + return nil + } + err := handle.StopAsPamUser() + if err != nil { + return err + } + _, err = keyring.UserKeyringID(handle.PamUser, true) + if err != nil { + log.Printf("Setting up keyrings in PAM: %v", err) + } + return handle.StartAsPamUser() +} + // OpenSession provisions any policies protected with the login protector. func OpenSession(handle *pam.Handle, _ map[string]bool) error { // We will always clear the AUTHTOK data @@ -107,6 +145,10 @@ func OpenSession(handle *pam.Handle, _ map[string]bool) error { return nil } + if err = setupUserKeyringIfNeeded(handle, policies); err != nil { + return errors.Wrapf(err, "setting up user keyring") + } + log.Printf("unlocking %d policies protected with AUTHTOK", len(policies)) keyFn := func(_ actions.ProtectorInfo, retry bool) (*crypto.Key, error) { if retry { @@ -134,8 +176,9 @@ func OpenSession(handle *pam.Handle, _ map[string]bool) error { // We don't stop provisioning polices on error, we try all of them. for _, policy := range policies { - if policy.IsProvisioned() { - log.Printf("policy %s already provisioned", policy.Descriptor()) + if policy.IsProvisionedByTargetUser() { + log.Printf("policy %s already provisioned by %v", + policy.Descriptor(), handle.PamUser.Username) continue } if err := policy.UnlockWithProtector(protector); err != nil { @@ -144,11 +187,19 @@ func OpenSession(handle *pam.Handle, _ map[string]bool) error { } defer policy.Lock() - if err := policy.Provision(); err != nil { - log.Printf("provisioning policy %s: %s", policy.Descriptor(), err) + if err := beginProvisioningOp(handle, policy); err != nil { + return err + } + provisionErr := policy.Provision() + if err := endProvisioningOp(handle, policy); err != nil { + return err + } + if provisionErr != nil { + log.Printf("provisioning policy %s: %s", policy.Descriptor(), provisionErr) continue } - log.Printf("policy %s provisioned", policy.Descriptor()) + log.Printf("policy %s provisioned by %v", policy.Descriptor(), + handle.PamUser.Username) } return nil } @@ -163,7 +214,8 @@ func CloseSession(handle *pam.Handle, args map[string]bool) error { } var errLock, errCache error - // Don't automatically drop privileges, we may need them to drop caches. + // Don't automatically drop privileges, since we may need them to + // deprovision policies or to drop caches. if args[lockFlag] { log.Print("locking polices protected with login protector") errLock = lockLoginPolicies(handle) @@ -200,17 +252,29 @@ func lockLoginPolicies(handle *pam.Handle) error { return nil } + if err = setupUserKeyringIfNeeded(handle, policies); err != nil { + return errors.Wrapf(err, "setting up user keyring") + } + // We will try to deprovision all of the policies. for _, policy := range policies { - if !policy.IsProvisioned() { - log.Printf("policy %s not provisioned", policy.Descriptor()) + if !policy.IsProvisionedByTargetUser() { + log.Printf("policy %s not provisioned by %v", + policy.Descriptor(), handle.PamUser.Username) continue } - if err := policy.Deprovision(); err != nil { - log.Printf("deprovisioning policy %s: %s", policy.Descriptor(), err) + if err := beginProvisioningOp(handle, policy); err != nil { + return err + } + deprovisionErr := policy.Deprovision(false) + if err := endProvisioningOp(handle, policy); err != nil { + return err + } + if deprovisionErr != nil { + log.Printf("deprovisioning policy %s: %s", policy.Descriptor(), deprovisionErr) continue } - log.Printf("policy %s deprovisioned", policy.Descriptor()) + log.Printf("policy %s deprovisioned by %v", policy.Descriptor(), handle.PamUser.Username) } return nil } diff --git a/security/privileges.go b/security/privileges.go index 3a1ca81..e5751b5 100644 --- a/security/privileges.go +++ b/security/privileges.go @@ -19,9 +19,7 @@ // Package security manages: // - Cache clearing (cache.go) -// - Keyring Operations (keyring.go) // - Privilege manipulation (privileges.go) -// - Maintaining the link between the root and user keyrings. package security // Use the libc versions of setreuid, setregid, and setgroups instead of the @@ -142,7 +140,8 @@ func SetProcessPrivileges(privs *Privileges) error { return nil } -func setUids(ruid, euid, suid int) error { +// SetUids sets the process's real, effective, and saved UIDs. +func SetUids(ruid, euid, suid int) error { log.Printf("Setting ruid=%d euid=%d suid=%d", ruid, euid, suid) // We elevate all the privs before setting them. This prevents issues // with (ruid=1000,euid=1000,suid=0), where just a single call to @@ -156,7 +155,8 @@ func setUids(ruid, euid, suid int) error { return nil } -func getUids() (int, int, int) { +// GetUids gets the process's real, effective, and saved UIDs. +func GetUids() (int, int, int) { var ruid, euid, suid C.uid_t C.getresuid(&ruid, &euid, &suid) return int(ruid), int(euid), int(suid) |