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916ef6232c
Verity targets can be configured to ignore corrupted data blocks.
LoadPin must only trust verity targets that are configured to
perform some kind of enforcement when data corruption is detected,
like returning an error, restarting the system or triggering a
panic.
Fixes: b6c1c5745c ("dm: Add verity helpers for LoadPin")
Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220907133055.1.Ic8a1dafe960dc0f8302e189642bc88ebb785d274@changeid
83 lines
1.7 KiB
C
83 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 (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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