selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c
new file mode 100644
index 000000000..d8a7bde94
--- /dev/null
+++ b/security/apparmor/crypto.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy loading interface function definitions.
+ *
+ * Copyright 2013 Canonical Ltd.
+ *
+ * Fns to provide a checksum of policy that has been loaded this can be
+ * compared to userspace policy compiles to check loaded policy is what
+ * it should be.
+ */
+
+#include <crypto/sha2.h>
+
+#include "include/apparmor.h"
+#include "include/crypto.h"
+
+unsigned int aa_hash_size(void)
+{
+	return SHA256_DIGEST_SIZE;
+}
+
+char *aa_calc_hash(void *data, size_t len)
+{
+	char *hash;
+
+	hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
+	if (!hash)
+		return ERR_PTR(-ENOMEM);
+
+	sha256(data, len, hash);
+	return hash;
+}
+
+int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
+			 size_t len)
+{
+	struct sha256_ctx sctx;
+	__le32 le32_version = cpu_to_le32(version);
+
+	if (!aa_g_hash_policy)
+		return 0;
+
+	profile->hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
+	if (!profile->hash)
+		return -ENOMEM;
+
+	sha256_init(&sctx);
+	sha256_update(&sctx, (u8 *)&le32_version, 4);
+	sha256_update(&sctx, (u8 *)start, len);
+	sha256_final(&sctx, profile->hash);
+	return 0;
+}
+
+int __init init_profile_hash(void)
+{
+	if (apparmor_initialized)
+		aa_info_message("AppArmor sha256 policy hashing enabled");
+	return 0;
+}