mirror of
https://git.proxmox.com/git/mirror_ubuntu-kernels.git
synced 2025-11-25 14:26:44 +00:00
b6c1c5745c
LoadPin limits loading of kernel modules, firmware and certain other files to a 'pinned' file system (typically a read-only rootfs). To provide more flexibility LoadPin is being extended to also allow loading these files from trusted dm-verity devices. For that purpose LoadPin can be provided with a list of verity root digests that it should consider as trusted. Add a bunch of helpers to allow LoadPin to check whether a DM device is a trusted verity device. The new functions broadly fall in two categories: those that need access to verity internals (like the root digest), and the 'glue' between LoadPin and verity. The new file dm-verity-loadpin.c contains the glue functions. Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Acked-by: Mike Snitzer <snitzer@kernel.org> Link: https://lore.kernel.org/lkml/20220627083512.v7.1.I3e928575a23481121e73286874c4c2bdb403355d@changeid Signed-off-by: Kees Cook <keescook@chromium.org>
75 lines
1.5 KiB
C
75 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
#include <linux/list.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/dm-verity-loadpin.h>
|
|
|
|
#include "dm.h"
|
|
#include "dm-verity.h"
|
|
|
|
#define DM_MSG_PREFIX "verity-loadpin"
|
|
|
|
LIST_HEAD(dm_verity_loadpin_trusted_root_digests);
|
|
|
|
static bool is_trusted_verity_target(struct dm_target *ti)
|
|
{
|
|
u8 *root_digest;
|
|
unsigned int digest_size;
|
|
struct dm_verity_loadpin_trusted_root_digest *trd;
|
|
bool trusted = false;
|
|
|
|
if (!dm_is_verity_target(ti))
|
|
return false;
|
|
|
|
if (dm_verity_get_root_digest(ti, &root_digest, &digest_size))
|
|
return false;
|
|
|
|
list_for_each_entry(trd, &dm_verity_loadpin_trusted_root_digests, node) {
|
|
if ((trd->len == digest_size) &&
|
|
!memcmp(trd->data, root_digest, digest_size)) {
|
|
trusted = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
kfree(root_digest);
|
|
|
|
return trusted;
|
|
}
|
|
|
|
/*
|
|
* Determines whether the file system of a superblock is located on
|
|
* a verity device that is trusted by LoadPin.
|
|
*/
|
|
bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev)
|
|
{
|
|
struct mapped_device *md;
|
|
struct dm_table *table;
|
|
struct dm_target *ti;
|
|
int srcu_idx;
|
|
bool trusted = false;
|
|
|
|
if (list_empty(&dm_verity_loadpin_trusted_root_digests))
|
|
return false;
|
|
|
|
md = dm_get_md(bdev->bd_dev);
|
|
if (!md)
|
|
return false;
|
|
|
|
table = dm_get_live_table(md, &srcu_idx);
|
|
|
|
if (dm_table_get_num_targets(table) != 1)
|
|
goto out;
|
|
|
|
ti = dm_table_get_target(table, 0);
|
|
|
|
if (is_trusted_verity_target(ti))
|
|
trusted = true;
|
|
|
|
out:
|
|
dm_put_live_table(md, srcu_idx);
|
|
dm_put(md);
|
|
|
|
return trusted;
|
|
}
|