From 78a1b96bcf7a0721c7852bb1475218c3cbef884a Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Sun, 4 Aug 2019 19:35:47 -0700 Subject: fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS ioctl Add a root-only variant of the FS_IOC_REMOVE_ENCRYPTION_KEY ioctl which removes all users' claims of the key, not just the current user's claim. I.e., it always removes the key itself, no matter how many users have added it. This is useful for forcing a directory to be locked, without having to figure out which user ID(s) the key was added under. This is planned to be used by a command like 'sudo fscrypt lock DIR --all-users' in the fscrypt userspace tool (http://github.com/google/fscrypt). Reviewed-by: Theodore Ts'o Signed-off-by: Eric Biggers --- fs/crypto/keyring.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) (limited to 'fs/crypto') diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index c654effb83f5..8c600ead0e2e 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -11,6 +11,7 @@ * * - FS_IOC_ADD_ENCRYPTION_KEY * - FS_IOC_REMOVE_ENCRYPTION_KEY + * - FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS * - FS_IOC_GET_ENCRYPTION_KEY_STATUS * * See the "User API" section of Documentation/filesystems/fscrypt.rst for more @@ -699,8 +700,10 @@ static int try_to_lock_encrypted_files(struct super_block *sb, /* * Try to remove an fscrypt master encryption key. * - * This removes the current user's claim to the key, then removes the key itself - * if no other users have claims. + * FS_IOC_REMOVE_ENCRYPTION_KEY (all_users=false) removes the current user's + * claim to the key, then removes the key itself if no other users have claims. + * FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS (all_users=true) always removes the + * key itself. * * To "remove the key itself", first we wipe the actual master key secret, so * that no more inodes can be unlocked with it. Then we try to evict all cached @@ -715,7 +718,7 @@ static int try_to_lock_encrypted_files(struct super_block *sb, * For more details, see the "Removing keys" section of * Documentation/filesystems/fscrypt.rst. */ -int fscrypt_ioctl_remove_key(struct file *filp, void __user *_uarg) +static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users) { struct super_block *sb = file_inode(filp)->i_sb; struct fscrypt_remove_key_arg __user *uarg = _uarg; @@ -751,9 +754,12 @@ int fscrypt_ioctl_remove_key(struct file *filp, void __user *_uarg) down_write(&key->sem); - /* If relevant, remove current user's claim to the key */ + /* If relevant, remove current user's (or all users) claim to the key */ if (mk->mk_users && mk->mk_users->keys.nr_leaves_on_tree != 0) { - err = remove_master_key_user(mk); + if (all_users) + err = keyring_clear(mk->mk_users); + else + err = remove_master_key_user(mk); if (err) { up_write(&key->sem); goto out_put_key; @@ -809,8 +815,21 @@ out_put_key: err = put_user(status_flags, &uarg->removal_status_flags); return err; } + +int fscrypt_ioctl_remove_key(struct file *filp, void __user *uarg) +{ + return do_remove_key(filp, uarg, false); +} EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key); +int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *uarg) +{ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + return do_remove_key(filp, uarg, true); +} +EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key_all_users); + /* * Retrieve the status of an fscrypt master encryption key. * -- cgit v1.2.3