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ipe: protect the dm-verity root hash with RCU

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ipe_bdev_setintegrity() frees the old root hash when dm-verity publishes
a new one on ->preresume, while policy evaluation can still be
dereferencing it.

Protect the root hash with RCU. The evaluation path already runs under
rcu_read_lock().

Fixes: e155858dd9 ("ipe: add support for dm-verity as a trust provider")
Cc: stable@vger.kernel.org
Assisted-by: LLM
[FW: remove model name according to latest guideline]
Signed-off-by: Fan Wu <wufan@kernel.org>
This commit is contained in:
Fan Wu 2026-09-22 20:13:49 -07:00
parent 9814077275
commit 2776e9c285
3 changed files with 26 additions and 10 deletions
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12
security/ipe/eval.c
View File

@ -134,10 +134,14 @@ static bool evaluate_boot_verified(const struct ipe_eval_ctx *const ctx)
static bool evaluate_dmv_roothash(const struct ipe_eval_ctx *const ctx,
struct ipe_prop *p)
{
return !!ctx->ipe_bdev &&
!!ctx->ipe_bdev->root_hash &&
ipe_digest_eval(p->value,
ctx->ipe_bdev->root_hash);
const struct digest_info *root_hash;
if (!ctx->ipe_bdev)
return false;
root_hash = rcu_dereference(ctx->ipe_bdev->root_hash);
return root_hash && ipe_digest_eval(p->value, root_hash);
}
#else
static bool evaluate_dmv_roothash(const struct ipe_eval_ctx *const ctx,

2
security/ipe/eval.h
View File

@ -27,7 +27,7 @@ struct ipe_bdev {
#ifdef CONFIG_IPE_PROP_DM_VERITY_SIGNATURE
bool dm_verity_signed;
#endif /* CONFIG_IPE_PROP_DM_VERITY_SIGNATURE */
struct digest_info *root_hash;
struct digest_info __rcu *root_hash;
};
#endif /* CONFIG_IPE_PROP_DM_VERITY */

22
security/ipe/hooks.c
View File

@ -9,6 +9,7 @@
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/blk_types.h>
#include <linux/rcupdate.h>
#include "ipe.h"
#include "hooks.h"
@ -232,7 +233,20 @@ void ipe_bdev_free_security(struct block_device *bdev)
{
struct ipe_bdev *blob = ipe_bdev(bdev);
ipe_digest_free(blob->root_hash);
ipe_digest_free(rcu_access_pointer(blob->root_hash));
}
static void ipe_set_dmverity_roothash(struct ipe_bdev *blob,
struct digest_info *info)
{
struct digest_info *old;
/* Protected by device-mapper's md->suspend_lock */
old = rcu_replace_pointer(blob->root_hash, info, true);
if (old) {
synchronize_rcu();
ipe_digest_free(old);
}
}
#ifdef CONFIG_IPE_PROP_DM_VERITY_SIGNATURE
@ -280,8 +294,7 @@ int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type typ
return -EINVAL;
if (!value) {
ipe_digest_free(blob->root_hash);
blob->root_hash = NULL;
ipe_set_dmverity_roothash(blob, NULL);
return 0;
}
@ -301,8 +314,7 @@ int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type typ
info->digest_len = digest->digest_len;
ipe_digest_free(blob->root_hash);
blob->root_hash = info;
ipe_set_dmverity_roothash(blob, info);
return 0;
err: