ipe/stable-7.3 PR 20260925

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Merge tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe

Pull IPE fixes from Fan Wu:
 "Two fixes for use-after-free issues found by recent LLM-assisted code
  analysis.

   - move successful policy load auditing under the new policy
     directory's inode lock, preventing a concurrent policy deletion
     from freeing the policy while it is still being audited

   - protect the dm-verity root hash with RCU, preventing policy
     evaluation from racing with root hash replacement during preresume"

* tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe:
  ipe: protect the dm-verity root hash with RCU
  ipe: fix use-after-free when auditing a newly loaded policy

security/ipe/eval.c

@@ -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,

security/ipe/eval.h

@@ -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 */
 

security/ipe/fs.c

@@ -159,18 +159,16 @@ static ssize_t new_policy(struct file *f, const char __user *data,
 	}
 
 	rc = ipe_new_policyfs_node(p);
-	if (rc)
-		goto out;
 
 out:
 	kfree(copy);
 	if (rc < 0) {
 		ipe_free_policy(p);
 		ipe_audit_policy_load(ERR_PTR(rc));
-	} else {
-		ipe_audit_policy_load(p);
+		return rc;
 	}
-	return (rc < 0) ? rc : len;
+
+	return len;
 }
 
 static const struct file_operations np_fops = {

security/ipe/hooks.c

@@ -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:

security/ipe/policy_fs.c

@@ -481,6 +481,9 @@ int ipe_new_policyfs_node(struct ipe_policy *p)
 	inode_lock(root);
 	p->policyfs = policyfs;
 	root->i_private = p;
+	/* Only audit signed policies from userspace */
+	if (p->pkcs7)
+		ipe_audit_policy_load(p);
 	inode_unlock(root);
 
 	return 0;