diff options
| -rw-r--r-- | Documentation/filesystems/fscrypt.rst | 12 | ||||
| -rw-r--r-- | fs/crypto/hooks.c | 6 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 3 | ||||
| -rw-r--r-- | include/linux/fscrypt.h | 4 |
4 files changed, 16 insertions, 9 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 43dd989e2a3f..08c23b60e016 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -451,10 +451,18 @@ astute users may notice some differences in behavior: - Unencrypted files, or files encrypted with a different encryption policy (i.e. different key, modes, or flags), cannot be renamed or linked into an encrypted directory; see `Encryption policy - enforcement`_. Attempts to do so will fail with EPERM. However, + enforcement`_. Attempts to do so will fail with EXDEV. However, encrypted files can be renamed within an encrypted directory, or into an unencrypted directory. + Note: "moving" an unencrypted file into an encrypted directory, e.g. + with the `mv` program, is implemented in userspace by a copy + followed by a delete. Be aware that the original unencrypted data + may remain recoverable from free space on the disk; prefer to keep + all files encrypted from the very beginning. The `shred` program + may be used to overwrite the source files but isn't guaranteed to be + effective on all filesystems and storage devices. + - Direct I/O is not supported on encrypted files. Attempts to use direct I/O on such files will fall back to buffered I/O. @@ -541,7 +549,7 @@ not be encrypted. Except for those special files, it is forbidden to have unencrypted files, or files encrypted with a different encryption policy, in an encrypted directory tree. Attempts to link or rename such a file into -an encrypted directory will fail with EPERM. This is also enforced +an encrypted directory will fail with EXDEV. This is also enforced during ->lookup() to provide limited protection against offline attacks that try to disable or downgrade encryption in known locations where applications may later write sensitive data. It is recommended diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 926e5df20ec3..56debb1fcf5e 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -58,7 +58,7 @@ int __fscrypt_prepare_link(struct inode *inode, struct inode *dir) return err; if (!fscrypt_has_permitted_context(dir, inode)) - return -EPERM; + return -EXDEV; return 0; } @@ -82,13 +82,13 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, if (IS_ENCRYPTED(new_dir) && !fscrypt_has_permitted_context(new_dir, d_inode(old_dentry))) - return -EPERM; + return -EXDEV; if ((flags & RENAME_EXCHANGE) && IS_ENCRYPTED(old_dir) && !fscrypt_has_permitted_context(old_dir, d_inode(new_dentry))) - return -EPERM; + return -EXDEV; } return 0; } diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index f490de921ce8..bd7eaf9b3f00 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -151,8 +151,7 @@ EXPORT_SYMBOL(fscrypt_ioctl_get_policy); * malicious offline violations of this constraint, while the link and rename * checks are needed to prevent online violations of this constraint. * - * Return: 1 if permitted, 0 if forbidden. If forbidden, the caller must fail - * the filesystem operation with EPERM. + * Return: 1 if permitted, 0 if forbidden. */ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) { diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index eec604840568..e5194fc3983e 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -489,7 +489,7 @@ static inline int fscrypt_require_key(struct inode *inode) * in an encrypted directory tree use the same encryption policy. * * Return: 0 on success, -ENOKEY if the directory's encryption key is missing, - * -EPERM if the link would result in an inconsistent encryption policy, or + * -EXDEV if the link would result in an inconsistent encryption policy, or * another -errno code. */ static inline int fscrypt_prepare_link(struct dentry *old_dentry, @@ -519,7 +519,7 @@ static inline int fscrypt_prepare_link(struct dentry *old_dentry, * We also verify that the rename will not violate the constraint that all files * in an encrypted directory tree use the same encryption policy. * - * Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the + * Return: 0 on success, -ENOKEY if an encryption key is missing, -EXDEV if the * rename would cause inconsistent encryption policies, or another -errno code. */ static inline int fscrypt_prepare_rename(struct inode *old_dir, |