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, 35 insertions, 0 deletions

diff --git a/include/keys/asymmetric-parser.h b/include/keys/asymmetric-parser.h
new file mode 100644
index 000000000..516a3f511
--- /dev/null
+++ b/include/keys/asymmetric-parser.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Asymmetric public-key cryptography data parser
+ *
+ * See Documentation/crypto/asymmetric-keys.rst
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _KEYS_ASYMMETRIC_PARSER_H
+#define _KEYS_ASYMMETRIC_PARSER_H
+
+struct key_preparsed_payload;
+
+/*
+ * Key data parser.  Called during key instantiation.
+ */
+struct asymmetric_key_parser {
+	struct list_head	link;
+	struct module		*owner;
+	const char		*name;
+
+	/* Attempt to parse a key from the data blob passed to add_key() or
+	 * keyctl_instantiate().  Should also generate a proposed description
+	 * that the caller can optionally use for the key.
+	 *
+	 * Return EBADMSG if not recognised.
+	 */
+	int (*parse)(struct key_preparsed_payload *prep);
+};
+
+extern int register_asymmetric_key_parser(struct asymmetric_key_parser *);
+extern void unregister_asymmetric_key_parser(struct asymmetric_key_parser *);
+
+#endif /* _KEYS_ASYMMETRIC_PARSER_H */