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path: root/include/linux/fscrypt.h
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2019-05-12Merge tag 'upstream-5.2-rc1' of ↵Linus Torvalds
ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs Pull UBI/UBIFS updates from Richard Weinberger: - fscrypt framework usage updates - One huge fix for xattr unlink - Cleanup of fscrypt ifdefs - Fix for our new UBIFS auth feature * tag 'upstream-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs: ubi: wl: Fix uninitialized variable ubifs: Drop unnecessary setting of zbr->znode ubifs: Remove ifdefs around CONFIG_UBIFS_ATIME_SUPPORT ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTION ubifs: Limit number of xattrs per inode ubifs: orphan: Handle xattrs like files ubifs: journal: Handle xattrs like files ubifs: find.c: replace swap function with built-in one ubifs: Do not skip hash checking in data nodes ubifs: work around high stack usage with clang ubifs: remove unused function __ubifs_shash_final ubifs: remove unnecessary #ifdef around fscrypt_ioctl_get_policy() ubifs: remove unnecessary calls to set up directory key
2019-05-07ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTIONSascha Hauer
ifdefs reduce readablity and compile coverage. This removes the ifdefs around CONFIG_FS_ENCRYPTION by using IS_ENABLED and relying on static inline wrappers. A new static inline wrapper for setting sb->s_cop is introduced to allow filesystems to unconditionally compile in their s_cop operations. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-04-17fscrypt: cache decrypted symlink target in ->i_linkEric Biggers
Path lookups that traverse encrypted symlink(s) are very slow because each encrypted symlink needs to be decrypted each time it's followed. This also involves dropping out of rcu-walk mode. Make encrypted symlinks faster by caching the decrypted symlink target in ->i_link. The first call to fscrypt_get_symlink() sets it. Then, the existing VFS path lookup code uses the non-NULL ->i_link to take the fast path where ->get_link() isn't called, and lookups in rcu-walk mode remain in rcu-walk mode. Also set ->i_link immediately when a new encrypted symlink is created. To safely free the symlink target after an RCU grace period has elapsed, introduce a new function fscrypt_free_inode(), and make the relevant filesystems call it just before actually freeing the inode. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-17fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertextEric Biggers
->lookup() in an encrypted directory begins as follows: 1. fscrypt_prepare_lookup(): a. Try to load the directory's encryption key. b. If the key is unavailable, mark the dentry as a ciphertext name via d_flags. 2. fscrypt_setup_filename(): a. Try to load the directory's encryption key. b. If the key is available, encrypt the name (treated as a plaintext name) to get the on-disk name. Otherwise decode the name (treated as a ciphertext name) to get the on-disk name. But if the key is concurrently added, it may be found at (2a) but not at (1a). In this case, the dentry will be wrongly marked as a ciphertext name even though it was actually treated as plaintext. This will cause the dentry to be wrongly invalidated on the next lookup, potentially causing problems. For example, if the racy ->lookup() was part of sys_mount(), then the new mount will be detached when anything tries to access it. This is despite the mountpoint having a plaintext path, which should remain valid now that the key was added. Of course, this is only possible if there's a userspace race. Still, the additional kernel-side race is confusing and unexpected. Close the kernel-side race by changing fscrypt_prepare_lookup() to also set the on-disk filename (step 2b), consistent with the d_flags update. Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-17fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directoryEric Biggers
Make __d_move() clear DCACHE_ENCRYPTED_NAME on the source dentry. This is needed for when d_splice_alias() moves a directory's encrypted alias to its decrypted alias as a result of the encryption key being added. Otherwise, the decrypted alias will incorrectly be invalidated on the next lookup, causing problems such as unmounting a mount the user just mount()ed there. Note that we don't have to support arbitrary moves of this flag because fscrypt doesn't allow dentries with DCACHE_ENCRYPTED_NAME to be the source or target of a rename(). Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-17fscrypt: fix race allowing rename() and link() of ciphertext dentriesEric Biggers
Close some race conditions where fscrypt allowed rename() and link() on ciphertext dentries that had been looked up just prior to the key being concurrently added. It's better to return -ENOKEY in this case. This avoids doing the nonsensical thing of encrypting the names a second time when searching for the actual on-disk dir entries. It also guarantees that DCACHE_ENCRYPTED_NAME dentries are never rename()d, so the dcache won't have support all possible combinations of moving DCACHE_ENCRYPTED_NAME around during __d_move(). Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-17fscrypt: clean up and improve dentry revalidationEric Biggers
Make various improvements to fscrypt dentry revalidation: - Don't try to handle the case where the per-directory key is removed, as this can't happen without the inode (and dentries) being evicted. - Flag ciphertext dentries rather than plaintext dentries, since it's ciphertext dentries that need the special handling. - Avoid doing unnecessary work for non-ciphertext dentries. - When revalidating ciphertext dentries, try to set up the directory's i_crypt_info to make sure the key is really still absent, rather than invalidating all negative dentries as the previous code did. An old comment suggested we can't do this for locking reasons, but AFAICT this comment was outdated and it actually works fine. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-16fscrypt: use READ_ONCE() to access ->i_crypt_infoEric Biggers
->i_crypt_info starts out NULL and may later be locklessly set to a non-NULL value by the cmpxchg() in fscrypt_get_encryption_info(). But ->i_crypt_info is used directly, which technically is incorrect. It's a data race, and it doesn't include the data dependency barrier needed to safely dereference the pointer on at least one architecture. Fix this by using READ_ONCE() instead. Note: we don't need to use smp_load_acquire(), since dereferencing the pointer only requires a data dependency barrier, which is already included in READ_ONCE(). We also don't need READ_ONCE() in places where ->i_crypt_info is unconditionally dereferenced, since it must have already been checked. Also downgrade the cmpxchg() to cmpxchg_release(), since RELEASE semantics are sufficient on the write side. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-04-16fscrypt: drop inode argument from fscrypt_get_ctx()Eric Biggers
The only reason the inode is being passed to fscrypt_get_ctx() is to verify that the encryption key is available. However, all callers already ensure this because if we get as far as trying to do I/O to an encrypted file without the key, there's already a bug. Therefore, remove this unnecessary argument. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2019-01-23fscrypt: return -EXDEV for incompatible rename or link into encrypted dirEric Biggers
Currently, trying to rename or link a regular file, directory, or symlink into an encrypted directory fails with EPERM when the source file is unencrypted or is encrypted with a different encryption policy, and is on the same mountpoint. It is correct for the operation to fail, but the choice of EPERM breaks tools like 'mv' that know to copy rather than rename if they see EXDEV, but don't know what to do with EPERM. Our original motivation for EPERM was to encourage users to securely handle their data. Encrypting files by "moving" them into an encrypted directory can be insecure because the unencrypted data may remain in free space on disk, where it can later be recovered by an attacker. It's much better to encrypt the data from the start, or at least try to securely delete the source data e.g. using the 'shred' program. However, the current behavior hasn't been effective at achieving its goal because users tend to be confused, hack around it, and complain; see e.g. https://github.com/google/fscrypt/issues/76. And in some cases it's actually inconsistent or unnecessary. For example, 'mv'-ing files between differently encrypted directories doesn't work even in cases where it can be secure, such as when in userspace the same passphrase protects both directories. Yet, you *can* already 'mv' unencrypted files into an encrypted directory if the source files are on a different mountpoint, even though doing so is often insecure. There are probably better ways to teach users to securely handle their files. For example, the 'fscrypt' userspace tool could provide a command that migrates unencrypted files into an encrypted directory, acting like 'shred' on the source files and providing appropriate warnings depending on the type of the source filesystem and disk. Receiving errors on unimportant files might also force some users to disable encryption, thus making the behavior counterproductive. It's desirable to make encryption as unobtrusive as possible. Therefore, change the error code from EPERM to EXDEV so that tools looking for EXDEV will fall back to a copy. This, of course, doesn't prevent users from still doing the right things to securely manage their files. Note that this also matches the behavior when a file is renamed between two project quota hierarchies; so there's precedent for using EXDEV for things other than mountpoints. xfstests generic/398 will require an update with this change. [Rewritten from an earlier patch series by Michael Halcrow.] Cc: Michael Halcrow <mhalcrow@google.com> Cc: Joe Richey <joerichey@google.com> Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-01-23fscrypt: remove filesystem specific build config optionChandan Rajendra
In order to have a common code base for fscrypt "post read" processing for all filesystems which support encryption, this commit removes filesystem specific build config option (e.g. CONFIG_EXT4_FS_ENCRYPTION) and replaces it with a build option (i.e. CONFIG_FS_ENCRYPTION) whose value affects all the filesystems making use of fscrypt. Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Eric Biggers <ebiggers@google.com>
2018-01-11fscrypt: move fscrypt_symlink_data to fscrypt_private.hEric Biggers
Now that all filesystems have been converted to use the symlink helper functions, they no longer need the declaration of 'struct fscrypt_symlink_data'. Move it from fscrypt.h to fscrypt_private.h. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: new helper functions for ->symlink()Eric Biggers
Currently, filesystems supporting fscrypt need to implement some tricky logic when creating encrypted symlinks, including handling a peculiar on-disk format (struct fscrypt_symlink_data) and correctly calculating the size of the encrypted symlink. Introduce helper functions to make things a bit easier: - fscrypt_prepare_symlink() computes and validates the size the symlink target will require on-disk. - fscrypt_encrypt_symlink() creates the encrypted target if needed. The new helpers actually fix some subtle bugs. First, when checking whether the symlink target was too long, filesystems didn't account for the fact that the NUL padding is meant to be truncated if it would cause the maximum length to be exceeded, as is done for filenames in directories. Consequently users would receive ENAMETOOLONG when creating symlinks close to what is supposed to be the maximum length. For example, with EXT4 with a 4K block size, the maximum symlink target length in an encrypted directory is supposed to be 4093 bytes (in comparison to 4095 in an unencrypted directory), but in FS_POLICY_FLAGS_PAD_32-mode only up to 4064 bytes were accepted. Second, symlink targets of "." and ".." were not being encrypted, even though they should be, as these names are special in *directory entries* but not in symlink targets. Fortunately, we can fix this simply by starting to encrypt them, as old kernels already accept them in encrypted form. Third, the output string length the filesystems were providing when doing the actual encryption was incorrect, as it was forgotten to exclude 'sizeof(struct fscrypt_symlink_data)'. Fortunately though, this bug didn't make a difference. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: trim down fscrypt.h includesEric Biggers
fscrypt.h included way too many other headers, given that it is included by filesystems both with and without encryption support. Trim down the includes list by moving the needed includes into more appropriate places, and removing the unneeded ones. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_is_dot_dotdot() to fs/crypto/fname.cEric Biggers
Only fs/crypto/fname.c cares about treating the "." and ".." filenames specially with regards to encryption, so move fscrypt_is_dot_dotdot() from fscrypt.h to there. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_valid_enc_modes() to fscrypt_private.hEric Biggers
The encryption modes are validated by fs/crypto/, not by individual filesystems. Therefore, move fscrypt_valid_enc_modes() from fscrypt.h to fscrypt_private.h. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_operations declaration to fscrypt_supp.hEric Biggers
Filesystems now only define their fscrypt_operations when they are compiled with encryption support, so move the fscrypt_operations declaration from fscrypt.h to fscrypt_supp.h. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: split fscrypt_dummy_context_enabled() into supp/notsupp versionsEric Biggers
fscrypt_dummy_context_enabled() accesses ->s_cop, which now is only set when the filesystem is built with encryption support. This didn't actually matter because no filesystems called it. However, it will start being used soon, so fix it by moving it from fscrypt.h to fscrypt_supp.h and stubbing it out in fscrypt_notsupp.h. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_ctx declaration to fscrypt_supp.hEric Biggers
Filesystems only ever access 'struct fscrypt_ctx' through fscrypt functions. But when a filesystem is built without encryption support, these functions are all stubbed out, so the declaration of fscrypt_ctx is unneeded. Therefore, move it from fscrypt.h to fscrypt_supp.h. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_control_page() to supp/notsupp headersEric Biggers
fscrypt_control_page() is already split into two versions depending on whether the filesystem is being built with encryption support or not. Move them into the appropriate headers. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-01-11fscrypt: move fscrypt_has_encryption_key() to supp/notsupp headersEric Biggers
fscrypt_has_encryption_key() is already split into two versions depending on whether the filesystem is being built with encryption support or not. Move them into the appropriate headers. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-11-14Merge tag 'fscrypt-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt Pull fscrypt updates from Ted Ts'o: "Lots of cleanups, mostly courtesy by Eric Biggers" * tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt: fscrypt: lock mutex before checking for bounce page pool fscrypt: add a documentation file for filesystem-level encryption ext4: switch to fscrypt_prepare_setattr() ext4: switch to fscrypt_prepare_lookup() ext4: switch to fscrypt_prepare_rename() ext4: switch to fscrypt_prepare_link() ext4: switch to fscrypt_file_open() fscrypt: new helper function - fscrypt_prepare_setattr() fscrypt: new helper function - fscrypt_prepare_lookup() fscrypt: new helper function - fscrypt_prepare_rename() fscrypt: new helper function - fscrypt_prepare_link() fscrypt: new helper function - fscrypt_file_open() fscrypt: new helper function - fscrypt_require_key() fscrypt: remove unneeded empty fscrypt_operations structs fscrypt: remove ->is_encrypted() fscrypt: switch from ->is_encrypted() to IS_ENCRYPTED() fs, fscrypt: add an S_ENCRYPTED inode flag fscrypt: clean up include file mess
2017-10-18fscrypt: new helper function - fscrypt_prepare_setattr()Eric Biggers
Introduce a helper function for filesystems to call when processing ->setattr() on a possibly-encrypted inode. It handles enforcing that an encrypted file can only be truncated if its encryption key is available. Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: new helper function - fscrypt_prepare_lookup()Eric Biggers
Introduce a helper function which prepares to look up the given dentry in the given directory. If the directory is encrypted, it handles loading the directory's encryption key, setting the dentry's ->d_op to fscrypt_d_ops, and setting DCACHE_ENCRYPTED_WITH_KEY if the directory's encryption key is available. Note: once all filesystems switch over to this, we'll be able to move fscrypt_d_ops and fscrypt_set_encrypted_dentry() to fscrypt_private.h. Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: new helper function - fscrypt_prepare_rename()Eric Biggers
Introduce a helper function which prepares to rename a file into a possibly encrypted directory. It handles loading the encryption keys for the source and target directories if needed, and it handles enforcing that if the target directory (and the source directory for a cross-rename) is encrypted, then the file being moved into the directory has the same encryption policy as its containing directory. Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: new helper function - fscrypt_prepare_link()Eric Biggers
Introduce a helper function which prepares to link an inode into a possibly-encrypted directory. It handles setting up the target directory's encryption key, then verifying that the link won't violate the constraint that all files in an encrypted directory tree use the same encryption policy. Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: new helper function - fscrypt_require_key()Eric Biggers
Add a helper function which checks if an inode is encrypted, and if so, tries to set up its encryption key. This is a pattern which is duplicated in multiple places in each of ext4, f2fs, and ubifs --- for example, when a regular file is asked to be opened or truncated. Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: remove ->is_encrypted()Eric Biggers
Now that all callers of fscrypt_operations.is_encrypted() have been switched to IS_ENCRYPTED(), remove ->is_encrypted(). Reviewed-by: Chao Yu <yuchao0@huawei.com> Acked-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-10-18fscrypt: clean up include file messDave Chinner
Filesystems have to include different header files based on whether they are compiled with encryption support or not. That's nasty and messy. Instead, rationalise the headers so we have a single include fscrypt.h and let it decide what internal implementation to include based on the __FS_HAS_ENCRYPTION define. Filesystems set __FS_HAS_ENCRYPTION to 1 before including linux/fscrypt.h if they are built with encryption support. Otherwise, they must set __FS_HAS_ENCRYPTION to 0. Add guards to prevent fscrypt_supp.h and fscrypt_notsupp.h from being directly included by filesystems. Signed-off-by: Dave Chinner <dchinner@redhat.com> [EB: use 1 and 0 rather than defined/undefined] Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>