Commit Graph

8 Commits

Author SHA1 Message Date
Eric Biggers bde4933490 fs-verity: move structs needed for file signing to UAPI header
Although it isn't used directly by the ioctls,
"struct fsverity_descriptor" is required by userspace programs that need
to compute fs-verity file digests in a standalone way.  Therefore
it's also needed to sign files in a standalone way.

Similarly, "struct fsverity_formatted_digest" (previously called
"struct fsverity_signed_digest" which was misleading) is also needed to
sign files if the built-in signature verification is being used.

Therefore, move these structs to the UAPI header.

While doing this, try to make it clear that the signature-related fields
in fsverity_descriptor aren't used in the file digest computation.

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-11-23 19:30:14 -08:00
Eric Biggers ed45e20164 fs-verity: rename "file measurement" to "file digest"
I originally chose the name "file measurement" to refer to the fs-verity
file digest to avoid confusion with traditional full-file digests or
with the bare root hash of the Merkle tree.

But the name "file measurement" hasn't caught on, and usually people are
calling it something else, usually the "file digest".  E.g. see
"struct fsverity_digest" and "struct fsverity_formatted_digest", the
libfsverity_compute_digest() and libfsverity_sign_digest() functions in
libfsverity, and the "fsverity digest" command.

Having multiple names for the same thing is always confusing.

So to hopefully avoid confusion in the future, rename
"fs-verity file measurement" to "fs-verity file digest".

This leaves FS_IOC_MEASURE_VERITY as the only reference to "measure" in
the kernel, which makes some amount of sense since the ioctl is actively
"measuring" the file.

I'll be renaming this in fsverity-utils too (though similarly the
'fsverity measure' command, which is a wrapper for
FS_IOC_MEASURE_VERITY, will stay).

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-11-16 11:40:12 -08:00
Eric Biggers 9e90f30e78 fs-verity: rename fsverity_signed_digest to fsverity_formatted_digest
The name "struct fsverity_signed_digest" is causing confusion because it
isn't actually a signed digest, but rather it's the way that the digest
is formatted in order to be signed.  Rename it to
"struct fsverity_formatted_digest" to prevent this confusion.

Also update the struct's comment to clarify that it's specific to the
built-in signature verification support and isn't a requirement for all
fs-verity users.

I'll be renaming this struct in fsverity-utils too.

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-11-16 11:40:11 -08:00
Mauro Carvalho Chehab 9303c9d5e9 docs: get rid of :c:type explicit declarations for structs
The :c:type:`foo` only works properly with structs before
Sphinx 3.x.

On Sphinx 3.x, structs should now be declared using the
.. c:struct, and referenced via :c:struct tag.

As we now have the automarkup.py macro, that automatically
convert:
	struct foo

into cross-references, let's get rid of that, solving
several warnings when building docs with Sphinx 3.x.

Reviewed-by: André Almeida <andrealmeid@collabora.com> # blk-mq.rst
Reviewed-by: Takashi Iwai <tiwai@suse.de> # sound
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
2020-10-15 07:49:40 +02:00
Randy Dunlap 59bc120ecd Documentation: filesystems: fsverity: drop doubled word
Drop the doubled word "the".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Theodore Y. Ts'o <tytso@mit.edu>
Cc: linux-fscrypt@vger.kernel.org
Link: https://lore.kernel.org/r/20200703214325.31036-6-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-05 14:44:29 -06:00
Eric Biggers 73f0ec02d6 docs: fs-verity: mention statx() support
Document that the statx() system call can now be used to check whether a
file is a verity file.

Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-11-13 12:15:34 -08:00
Eric Biggers c0d782a3cc docs: fs-verity: document first supported kernel version
I had meant to replace these TODOs with the actual version when applying
the patches, but forgot to do so.  Do it now.

Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-11-13 12:15:34 -08:00
Eric Biggers 6ff2deb2e8 fs-verity: add a documentation file
Add a documentation file for fs-verity, covering:

- Introduction
- Use cases
- User API
    - FS_IOC_ENABLE_VERITY
    - FS_IOC_MEASURE_VERITY
    - FS_IOC_GETFLAGS
- Accessing verity files
- File measurement computation
    - Merkle tree
    - fs-verity descriptor
- Built-in signature verification
- Filesystem support
    - ext4
    - f2fs
- Implementation details
    - Verifying data
        - Pagecache
        - Block device based filesystems
- Userspace utility
- Tests
- FAQ

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-07-28 16:59:15 -07:00