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authorLinus Torvalds <torvalds@linux-foundation.org>2018-02-04 21:43:12 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-04 21:43:12 +0300
commit3462ac57033e79a87dbae2497773f22b9c536fbc (patch)
tree08d0b98ac665ad0cd0e85bde0342fd2650424db5 /Documentation
parent617aebe6a97efa539cc4b8a52adccd89596e6be0 (diff)
parent0b1dfa4cc6c60052b2c30ead316fa84c46d3c43c (diff)
downloadlinux-3462ac57033e79a87dbae2497773f22b9c536fbc.tar.xz
Merge tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt
Pull fscrypt updates from Ted Ts'o: "Refactor support for encrypted symlinks to move common code to fscrypt" Ted also points out about the merge: "This makes the f2fs symlink code use the fscrypt_encrypt_symlink() from the fscrypt tree. This will end up dropping the kzalloc() -> f2fs_kzalloc() change, which means the fscrypt-specific allocation won't get tested by f2fs's kmalloc error injection system; which is fine" * tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt: (26 commits) fscrypt: fix build with pre-4.6 gcc versions fscrypt: remove 'ci' parameter from fscrypt_put_encryption_info() fscrypt: document symlink length restriction fscrypt: fix up fscrypt_fname_encrypted_size() for internal use fscrypt: define fscrypt_fname_alloc_buffer() to be for presented names fscrypt: calculate NUL-padding length in one place only fscrypt: move fscrypt_symlink_data to fscrypt_private.h fscrypt: remove fscrypt_fname_usr_to_disk() ubifs: switch to fscrypt_get_symlink() ubifs: switch to fscrypt ->symlink() helper functions ubifs: free the encrypted symlink target f2fs: switch to fscrypt_get_symlink() f2fs: switch to fscrypt ->symlink() helper functions ext4: switch to fscrypt_get_symlink() ext4: switch to fscrypt ->symlink() helper functions fscrypt: new helper function - fscrypt_get_symlink() fscrypt: new helper functions for ->symlink() fscrypt: trim down fscrypt.h includes fscrypt: move fscrypt_is_dot_dotdot() to fs/crypto/fname.c fscrypt: move fscrypt_valid_enc_modes() to fscrypt_private.h ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/fscrypt.rst10
1 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 776ddc655f79..cfbc18f0d9c9 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -448,8 +448,14 @@ astute users may notice some differences in behavior:
- The st_size of an encrypted symlink will not necessarily give the
length of the symlink target as required by POSIX. It will actually
- give the length of the ciphertext, which may be slightly longer than
- the plaintext due to the NUL-padding.
+ give the length of the ciphertext, which will be slightly longer
+ than the plaintext due to NUL-padding and an extra 2-byte overhead.
+
+- The maximum length of an encrypted symlink is 2 bytes shorter than
+ the maximum length of an unencrypted symlink. For example, on an
+ EXT4 filesystem with a 4K block size, unencrypted symlinks can be up
+ to 4095 bytes long, while encrypted symlinks can only be up to 4093
+ bytes long (both lengths excluding the terminating null).
Note that mmap *is* supported. This is possible because the pagecache
for an encrypted file contains the plaintext, not the ciphertext.