2 Commits

Author	SHA1	Message	Date
Eric Biggers	bb4f8ead47	f2fs: fix error handling in f2fs_end_enable_verity() ... commit 3c0315424f upstream. f2fs didn't properly clean up if verity failed to be enabled on a file: - It left verity metadata (pages past EOF) in the page cache, which would be exposed to userspace if the file was later extended. - It didn't truncate the verity metadata at all (either from cache or from disk) if an error occurred while setting the verity bit. Fix these bugs by adding a call to truncate_inode_pages() and ensuring that we truncate the verity metadata (both from cache and from disk) in all error paths. Also rework the code to cleanly separate the success path from the error paths, which makes it much easier to understand. Finally, log a message if f2fs_truncate() fails, since it might otherwise fail silently. Reported-by: Yunlei He <heyunlei@hihonor.com> Fixes: 95ae251fe8 ("f2fs: add fs-verity support") Cc: <stable@vger.kernel.org> # v5.4+ Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>	2021-05-19 10:08:32 +02:00
Eric Biggers	95ae251fe8	f2fs: add fs-verity support ... Add fs-verity support to f2fs. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for the full documentation. The f2fs support for fs-verity consists of: - Adding a filesystem feature flag and an inode flag for fs-verity. - Implementing the fsverity_operations to support enabling verity on an inode and reading/writing the verity metadata. - Updating ->readpages() to verify data as it's read from verity files and to support reading verity metadata pages. - Updating ->write_begin(), ->write_end(), and ->writepages() to support writing verity metadata pages. - Calling the fs-verity hooks for ->open(), ->setattr(), and ->ioctl(). Like ext4, f2fs stores the verity metadata (Merkle tree and fsverity_descriptor) past the end of the file, starting at the first 64K boundary beyond i_size. This approach works because (a) verity files are readonly, and (b) pages fully beyond i_size aren't visible to userspace but can be read/written internally by f2fs with only some relatively small changes to f2fs. Extended attributes cannot be used because (a) f2fs limits the total size of an inode's xattr entries to 4096 bytes, which wouldn't be enough for even a single Merkle tree block, and (b) f2fs encryption doesn't encrypt xattrs, yet the verity metadata *must* be encrypted when the file is because it contains hashes of the plaintext data. Acked-by: Jaegeuk Kim <jaegeuk@kernel.org> Acked-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Eric Biggers <ebiggers@google.com>	2019-08-12 19:33:51 -07:00