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, 133 insertions, 0 deletions

diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
new file mode 100644
index 000000000..a6c2897bc
--- /dev/null
+++ b/include/keys/system_keyring.h
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* System keyring containing trusted public keys.
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _KEYS_SYSTEM_KEYRING_H
+#define _KEYS_SYSTEM_KEYRING_H
+
+#include <linux/key.h>
+
+enum blacklist_hash_type {
+	/* TBSCertificate hash */
+	BLACKLIST_HASH_X509_TBS = 1,
+	/* Raw data hash */
+	BLACKLIST_HASH_BINARY = 2,
+};
+
+#ifdef CONFIG_SYSTEM_TRUSTED_KEYRING
+
+extern int restrict_link_by_builtin_trusted(struct key *keyring,
+					    const struct key_type *type,
+					    const union key_payload *payload,
+					    struct key *restriction_key);
+int restrict_link_by_digsig_builtin(struct key *dest_keyring,
+				    const struct key_type *type,
+				    const union key_payload *payload,
+				    struct key *restriction_key);
+extern __init int load_module_cert(struct key *keyring);
+
+#else
+#define restrict_link_by_builtin_trusted restrict_link_reject
+#define restrict_link_by_digsig_builtin restrict_link_reject
+
+static inline __init int load_module_cert(struct key *keyring)
+{
+	return 0;
+}
+
+#endif
+
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+extern int restrict_link_by_builtin_and_secondary_trusted(
+	struct key *keyring,
+	const struct key_type *type,
+	const union key_payload *payload,
+	struct key *restriction_key);
+int restrict_link_by_digsig_builtin_and_secondary(struct key *keyring,
+						  const struct key_type *type,
+						  const union key_payload *payload,
+						  struct key *restriction_key);
+void __init add_to_secondary_keyring(const char *source, const void *data, size_t len);
+#else
+#define restrict_link_by_builtin_and_secondary_trusted restrict_link_by_builtin_trusted
+#define restrict_link_by_digsig_builtin_and_secondary restrict_link_by_digsig_builtin
+static inline void __init add_to_secondary_keyring(const char *source, const void *data, size_t len)
+{
+}
+#endif
+
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+extern int restrict_link_by_builtin_secondary_and_machine(
+	struct key *dest_keyring,
+	const struct key_type *type,
+	const union key_payload *payload,
+	struct key *restrict_key);
+extern void __init set_machine_trusted_keys(struct key *keyring);
+#else
+#define restrict_link_by_builtin_secondary_and_machine restrict_link_by_builtin_trusted
+static inline void __init set_machine_trusted_keys(struct key *keyring)
+{
+}
+#endif
+
+#ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
+extern int mark_hash_blacklisted(const u8 *hash, size_t hash_len,
+			       enum blacklist_hash_type hash_type);
+extern int is_hash_blacklisted(const u8 *hash, size_t hash_len,
+			       enum blacklist_hash_type hash_type);
+extern int is_binary_blacklisted(const u8 *hash, size_t hash_len);
+#else
+static inline int is_hash_blacklisted(const u8 *hash, size_t hash_len,
+				      enum blacklist_hash_type hash_type)
+{
+	return 0;
+}
+
+static inline int is_binary_blacklisted(const u8 *hash, size_t hash_len)
+{
+	return 0;
+}
+#endif
+
+struct pkcs7_message;
+#ifdef CONFIG_SYSTEM_REVOCATION_LIST
+extern int add_key_to_revocation_list(const char *data, size_t size);
+extern int is_key_on_revocation_list(struct pkcs7_message *pkcs7);
+#else
+static inline int add_key_to_revocation_list(const char *data, size_t size)
+{
+	return 0;
+}
+static inline int is_key_on_revocation_list(struct pkcs7_message *pkcs7)
+{
+	return -ENOKEY;
+}
+#endif
+
+#ifdef CONFIG_IMA_BLACKLIST_KEYRING
+extern struct key *ima_blacklist_keyring;
+
+static inline struct key *get_ima_blacklist_keyring(void)
+{
+	return ima_blacklist_keyring;
+}
+#else
+static inline struct key *get_ima_blacklist_keyring(void)
+{
+	return NULL;
+}
+#endif /* CONFIG_IMA_BLACKLIST_KEYRING */
+
+#if defined(CONFIG_INTEGRITY_PLATFORM_KEYRING) && \
+	defined(CONFIG_SYSTEM_TRUSTED_KEYRING)
+extern void __init set_platform_trusted_keys(struct key *keyring);
+#else
+static inline void set_platform_trusted_keys(struct key *keyring)
+{
+}
+#endif
+
+#endif /* _KEYS_SYSTEM_KEYRING_H */