commit 80f6e3080b upstream.
If the file size is almost S64_MAX, the calculated number of Merkle tree
levels exceeds FS_VERITY_MAX_LEVELS, causing FS_IOC_ENABLE_VERITY to
fail. This is unintentional, since as the comment above the definition
of FS_VERITY_MAX_LEVELS states, it is enough for over U64_MAX bytes of
data using SHA-256 and 4K blocks. (Specifically, 4096*128**8 >= 2**64.)
The bug is actually that when the number of blocks in the first level is
calculated from i_size, there is a signed integer overflow due to i_size
being signed. Fix this by treating i_size as unsigned.
This was found by the new test "generic: test fs-verity EFBIG scenarios"
(https://lkml.kernel.org/r/b1d116cd4d0ea74b9cd86f349c672021e005a75c.1631558495.git.boris@bur.io).
This didn't affect ext4 or f2fs since those have a smaller maximum file
size, but it did affect btrfs which allows files up to S64_MAX bytes.
Reported-by: Boris Burkov <boris@bur.io>
Fixes: 3fda4c617e ("fs-verity: implement FS_IOC_ENABLE_VERITY ioctl")
Fixes: fd2d1acfca ("fs-verity: add the hook for file ->open()")
Cc: <stable@vger.kernel.org> # v5.4+
Reviewed-by: Boris Burkov <boris@bur.io>
Link: https://lore.kernel.org/r/20210916203424.113376-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 a function for filesystems to call to implement the
FS_IOC_ENABLE_VERITY ioctl. This ioctl enables fs-verity on a file.
See the "FS_IOC_ENABLE_VERITY" section of
Documentation/filesystems/fsverity.rst for the documentation.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
