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, 48 insertions, 0 deletions

diff --git a/rust/helpers/security.c b/rust/helpers/security.c
new file mode 100644
index 000000000..8d0a25fcf
--- /dev/null
+++ b/rust/helpers/security.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/security.h>
+
+#ifndef CONFIG_SECURITY
+__rust_helper void rust_helper_security_cred_getsecid(const struct cred *c,
+						      u32 *secid)
+{
+	security_cred_getsecid(c, secid);
+}
+
+__rust_helper int rust_helper_security_secid_to_secctx(u32 secid,
+						       struct lsm_context *cp)
+{
+	return security_secid_to_secctx(secid, cp);
+}
+
+__rust_helper void rust_helper_security_release_secctx(struct lsm_context *cp)
+{
+	security_release_secctx(cp);
+}
+
+__rust_helper int
+rust_helper_security_binder_set_context_mgr(const struct cred *mgr)
+{
+	return security_binder_set_context_mgr(mgr);
+}
+
+__rust_helper int
+rust_helper_security_binder_transaction(const struct cred *from,
+					const struct cred *to)
+{
+	return security_binder_transaction(from, to);
+}
+
+__rust_helper int
+rust_helper_security_binder_transfer_binder(const struct cred *from,
+					    const struct cred *to)
+{
+	return security_binder_transfer_binder(from, to);
+}
+
+__rust_helper int rust_helper_security_binder_transfer_file(
+	const struct cred *from, const struct cred *to, const struct file *file)
+{
+	return security_binder_transfer_file(from, to, file);
+}
+#endif