| 1 | // SPDX-License-Identifier: GPL-2.0-only |
|---|---|
| 2 | |
| 3 | #include <linux/list.h> |
| 4 | #include <linux/kernel.h> |
| 5 | #include <linux/dm-verity-loadpin.h> |
| 6 | |
| 7 | #include "dm.h" |
| 8 | #include "dm-core.h" |
| 9 | #include "dm-verity.h" |
| 10 | |
| 11 | #define DM_MSG_PREFIX "verity-loadpin" |
| 12 | |
| 13 | LIST_HEAD(dm_verity_loadpin_trusted_root_digests); |
| 14 | |
| 15 | static bool is_trusted_verity_target(struct dm_target *ti) |
| 16 | { |
| 17 | int verity_mode; |
| 18 | u8 *root_digest; |
| 19 | unsigned int digest_size; |
| 20 | struct dm_verity_loadpin_trusted_root_digest *trd; |
| 21 | bool trusted = false; |
| 22 | |
| 23 | if (!dm_is_verity_target(ti)) |
| 24 | return false; |
| 25 | |
| 26 | verity_mode = dm_verity_get_mode(ti); |
| 27 | |
| 28 | if ((verity_mode != DM_VERITY_MODE_EIO) && |
| 29 | (verity_mode != DM_VERITY_MODE_RESTART) && |
| 30 | (verity_mode != DM_VERITY_MODE_PANIC)) |
| 31 | return false; |
| 32 | |
| 33 | if (dm_verity_get_root_digest(ti, root_digest: &root_digest, digest_size: &digest_size)) |
| 34 | return false; |
| 35 | |
| 36 | list_for_each_entry(trd, &dm_verity_loadpin_trusted_root_digests, node) { |
| 37 | if ((trd->len == digest_size) && |
| 38 | !memcmp(p: trd->data, q: root_digest, size: digest_size)) { |
| 39 | trusted = true; |
| 40 | break; |
| 41 | } |
| 42 | } |
| 43 | |
| 44 | kfree(objp: root_digest); |
| 45 | |
| 46 | return trusted; |
| 47 | } |
| 48 | |
| 49 | /* |
| 50 | * Determines whether the file system of a superblock is located on |
| 51 | * a verity device that is trusted by LoadPin. |
| 52 | */ |
| 53 | bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev) |
| 54 | { |
| 55 | struct mapped_device *md; |
| 56 | struct dm_table *table; |
| 57 | struct dm_target *ti; |
| 58 | int srcu_idx; |
| 59 | bool trusted = false; |
| 60 | |
| 61 | if (bdev == NULL) |
| 62 | return false; |
| 63 | |
| 64 | if (list_empty(head: &dm_verity_loadpin_trusted_root_digests)) |
| 65 | return false; |
| 66 | |
| 67 | md = dm_get_md(dev: bdev->bd_dev); |
| 68 | if (!md) |
| 69 | return false; |
| 70 | |
| 71 | table = dm_get_live_table(md, srcu_idx: &srcu_idx); |
| 72 | |
| 73 | if (table->num_targets != 1) |
| 74 | goto out; |
| 75 | |
| 76 | ti = dm_table_get_target(t: table, index: 0); |
| 77 | |
| 78 | if (is_trusted_verity_target(ti)) |
| 79 | trusted = true; |
| 80 | |
| 81 | out: |
| 82 | dm_put_live_table(md, srcu_idx); |
| 83 | dm_put(md); |
| 84 | |
| 85 | return trusted; |
| 86 | } |
| 87 |