From: Eric Biggers <ebiggers@xxxxxxxxxx> Document that encryption reduces the maximum length of a symlink target slightly. Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- Documentation/filesystems/fscrypt.rst | 10 ++++++++-- 1 file 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. -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fscrypt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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