Currently the registration of the fsverity sysctls happens in
signature.c, which couples it to CONFIG_FS_VERITY_BUILTIN_SIGNATURES.
This makes it hard to add new sysctls unrelated to builtin signatures.
Also, some users have started checking whether the directory
/proc/sys/fs/verity exists as a way to tell whether fsverity is
supported. This isn't the intended method; instead, the existence of
/sys/fs/$fstype/features/verity should be checked, or users should just
try to use the fsverity ioctls. Regardless, it should be made to work
as expected without a dependency on CONFIG_FS_VERITY_BUILTIN_SIGNATURES.
Therefore, move the sysctl registration into init.c. With
CONFIG_FS_VERITY_BUILTIN_SIGNATURES, nothing changes. Without it, but
with CONFIG_FS_VERITY, an empty list of sysctls is now registered.
Link: https://lore.kernel.org/r/20230705212743.42180-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Since CONFIG_FS_VERITY is a bool, not a tristate, fs/verity/ can only be
builtin or absent entirely; it can't be a loadable module. Therefore,
the error code that gets returned from the fsverity_init() initcall is
never used. If any part of the initcall does fail, which should never
happen, the kernel will be left in a bad state.
Following the usual convention for builtin code, just panic the kernel
if any of part of the initcall fails.
Link: https://lore.kernel.org/r/20230705212743.42180-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
I've gotten very little use out of these debug messages, and I'm not
aware of anyone else having used them.
Indeed, sprinkling pr_debug around is not really a best practice these
days, especially for filesystem code. Tracepoints are used instead.
Let's just remove these and start from a clean slate.
This change does not affect info, warning, and error messages.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221215060420.60692-1-ebiggers@kernel.org
Embedding the file path inside kernel source code files isn't
particularly useful as often files are moved around and the paths become
incorrect. checkpatch.pl warns about this since v5.10-rc1.
Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
To meet some users' needs, add optional support for having fs-verity
handle a portion of the authentication policy in the kernel. An
".fs-verity" keyring is created to which X.509 certificates can be
added; then a sysctl 'fs.verity.require_signatures' can be set to cause
the kernel to enforce that all fs-verity files contain a signature of
their file measurement by a key in this keyring.
See the "Built-in signature verification" section of
Documentation/filesystems/fsverity.rst for the full documentation.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add functions that verify data pages that have been read from a
fs-verity file, against that file's Merkle tree. These will be called
from filesystems' ->readpage() and ->readpages() methods.
Since data verification can block, a workqueue is provided for these
methods to enqueue verification work from their bio completion callback.
See the "Verifying data" section of
Documentation/filesystems/fsverity.rst for more information.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add the fsverity_file_open() function, which prepares an fs-verity file
to be read from. If not already done, it loads the fs-verity descriptor
from the filesystem and sets up an fsverity_info structure for the inode
which describes the Merkle tree and contains the file measurement. It
also denies all attempts to open verity files for writing.
This commit also begins the include/linux/fsverity.h header, which
declares the interface between fs/verity/ and filesystems.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add the beginnings of the fs/verity/ support layer, including the
Kconfig option and various helper functions for hashing. To start, only
SHA-256 is supported, but other hash algorithms can easily be added.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
