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, 86 insertions, 0 deletions

diff --git a/include/net/gtp.h b/include/net/gtp.h
new file mode 100644
index 000000000..c0253c870
--- /dev/null
+++ b/include/net/gtp.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _GTP_H_
+#define _GTP_H_
+
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <net/rtnetlink.h>
+
+/* General GTP protocol related definitions. */
+
+#define GTP0_PORT	3386
+#define GTP1U_PORT	2152
+
+/* GTP messages types */
+#define GTP_ECHO_REQ	1	/* Echo Request */
+#define GTP_ECHO_RSP	2	/* Echo Response */
+#define GTP_TPDU	255
+
+#define GTPIE_RECOVERY	14
+
+struct gtp0_header {	/* According to GSM TS 09.60. */
+	__u8	flags;
+	__u8	type;
+	__be16	length;
+	__be16	seq;
+	__be16	flow;
+	__u8	number;
+	__u8	spare[3];
+	__be64	tid;
+} __attribute__ ((packed));
+
+struct gtp1_header {	/* According to 3GPP TS 29.060. */
+	__u8	flags;
+	__u8	type;
+	__be16	length;
+	__be32	tid;
+} __attribute__ ((packed));
+
+struct gtp1_header_long {	/* According to 3GPP TS 29.060. */
+	__u8	flags;
+	__u8	type;
+	__be16	length;
+	__be32	tid;
+	__be16	seq;
+	__u8	npdu;
+	__u8	next;
+} __packed;
+
+/* GTP Information Element */
+struct gtp_ie {
+	__u8	tag;
+	__u8	val;
+} __packed;
+
+struct gtp0_packet {
+	struct gtp0_header gtp0_h;
+	struct gtp_ie ie;
+} __packed;
+
+struct gtp1u_packet {
+	struct gtp1_header_long gtp1u_h;
+	struct gtp_ie ie;
+} __packed;
+
+struct gtp_pdu_session_info {	/* According to 3GPP TS 38.415. */
+	u8	pdu_type;
+	u8	qfi;
+};
+
+static inline bool netif_is_gtp(const struct net_device *dev)
+{
+	return dev->rtnl_link_ops &&
+		!strcmp(dev->rtnl_link_ops->kind, "gtp");
+}
+
+#define GTP1_F_NPDU	0x01
+#define GTP1_F_SEQ	0x02
+#define GTP1_F_EXTHDR	0x04
+#define GTP1_F_MASK	0x07
+
+struct gtp_ext_hdr {
+	__u8	len;
+	__u8	data[];
+};
+
+#endif