drivers/md/dm-verity-loadpin.c

   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, &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(trd->data, root_digest, digest_size)) {
  39                         trusted = true;
  40                         break;
  41                 }
  42         }
  43
  44         kfree(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(&dm_verity_loadpin_trusted_root_digests))
  65                 return false;
  66
  67         md = dm_get_md(bdev->bd_dev);
  68         if (!md)
  69                 return false;
  70
  71         table = dm_get_live_table(md, &srcu_idx);
  72
  73         if (table->num_targets != 1)
  74                 goto out;
  75
  76         ti = dm_table_get_target(table, 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 }