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47f04616f2
Add a NULL check for the 'bdev' parameter of
dm_verity_loadpin_is_bdev_trusted(). The function is called
by loadpin_check(), which passes the block device that
corresponds to the super block of the file system from which
a file is being loaded. Generally a super_block structure has
an associated block device, however that is not always the
case (e.g. tmpfs).
Cc: stable@vger.kernel.org # v6.0+
Fixes: b6c1c5745c ("dm: Add verity helpers for LoadPin")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/20230627202800.1.Id63f7f59536d20f1ab83e1abdc1fda1471c7d031@changeid
Signed-off-by: Kees Cook <keescook@chromium.org>
86 lines
1.7 KiB
C
86 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/list.h>
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#include <linux/kernel.h>
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#include <linux/dm-verity-loadpin.h>
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#include "dm.h"
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#include "dm-core.h"
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#include "dm-verity.h"
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#define DM_MSG_PREFIX "verity-loadpin"
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LIST_HEAD(dm_verity_loadpin_trusted_root_digests);
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static bool is_trusted_verity_target(struct dm_target *ti)
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{
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int verity_mode;
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u8 *root_digest;
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unsigned int digest_size;
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struct dm_verity_loadpin_trusted_root_digest *trd;
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bool trusted = false;
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if (!dm_is_verity_target(ti))
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return false;
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verity_mode = dm_verity_get_mode(ti);
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if ((verity_mode != DM_VERITY_MODE_EIO) &&
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(verity_mode != DM_VERITY_MODE_RESTART) &&
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(verity_mode != DM_VERITY_MODE_PANIC))
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return false;
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if (dm_verity_get_root_digest(ti, &root_digest, &digest_size))
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return false;
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list_for_each_entry(trd, &dm_verity_loadpin_trusted_root_digests, node) {
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if ((trd->len == digest_size) &&
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!memcmp(trd->data, root_digest, digest_size)) {
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trusted = true;
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break;
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}
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}
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kfree(root_digest);
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return trusted;
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}
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/*
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* Determines whether the file system of a superblock is located on
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* a verity device that is trusted by LoadPin.
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*/
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bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev)
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{
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struct mapped_device *md;
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struct dm_table *table;
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struct dm_target *ti;
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int srcu_idx;
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bool trusted = false;
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if (bdev == NULL)
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return false;
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if (list_empty(&dm_verity_loadpin_trusted_root_digests))
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return false;
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md = dm_get_md(bdev->bd_dev);
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if (!md)
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return false;
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table = dm_get_live_table(md, &srcu_idx);
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if (table->num_targets != 1)
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goto out;
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ti = dm_table_get_target(table, 0);
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if (is_trusted_verity_target(ti))
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trusted = true;
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out:
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dm_put_live_table(md, srcu_idx);
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dm_put(md);
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return trusted;
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}
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