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, 84 insertions, 0 deletions

diff --git a/include/net/gen_stats.h b/include/net/gen_stats.h
new file mode 100644
index 000000000..856b5e90f
--- /dev/null
+++ b/include/net/gen_stats.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_GEN_STATS_H
+#define __NET_GEN_STATS_H
+
+#include <linux/gen_stats.h>
+#include <linux/socket.h>
+#include <linux/rtnetlink.h>
+#include <linux/pkt_sched.h>
+
+/* Throughput stats.
+ * Must be initialized beforehand with gnet_stats_basic_sync_init().
+ *
+ * If no reads can ever occur parallel to writes (e.g. stack-allocated
+ * bstats), then the internal stat values can be written to and read
+ * from directly. Otherwise, use _bstats_set/update() for writes and
+ * gnet_stats_add_basic() for reads.
+ */
+struct gnet_stats_basic_sync {
+	u64_stats_t bytes;
+	u64_stats_t packets;
+	struct u64_stats_sync syncp;
+} __aligned(2 * sizeof(u64));
+
+struct net_rate_estimator;
+
+struct gnet_dump {
+	spinlock_t *      lock;
+	struct sk_buff *  skb;
+	struct nlattr *   tail;
+
+	/* Backward compatibility */
+	int               compat_tc_stats;
+	int               compat_xstats;
+	int               padattr;
+	void *            xstats;
+	int               xstats_len;
+	struct tc_stats   tc_stats;
+};
+
+void gnet_stats_basic_sync_init(struct gnet_stats_basic_sync *b);
+int gnet_stats_start_copy(struct sk_buff *skb, int type, spinlock_t *lock,
+			  struct gnet_dump *d, int padattr);
+
+int gnet_stats_start_copy_compat(struct sk_buff *skb, int type,
+				 int tc_stats_type, int xstats_type,
+				 spinlock_t *lock, struct gnet_dump *d,
+				 int padattr);
+
+int gnet_stats_copy_basic(struct gnet_dump *d,
+			  const struct gnet_stats_basic_sync __percpu *cpu,
+			  const struct gnet_stats_basic_sync *b, bool running);
+void gnet_stats_add_basic(struct gnet_stats_basic_sync *bstats,
+			  const struct gnet_stats_basic_sync __percpu *cpu,
+			  const struct gnet_stats_basic_sync *b, bool running);
+int gnet_stats_copy_basic_hw(struct gnet_dump *d,
+			     const struct gnet_stats_basic_sync __percpu *cpu,
+			     const struct gnet_stats_basic_sync *b, bool running);
+int gnet_stats_copy_rate_est(struct gnet_dump *d,
+			     struct net_rate_estimator __rcu **ptr);
+int gnet_stats_copy_queue(struct gnet_dump *d,
+			  const struct gnet_stats_queue __percpu *cpu_q,
+			  const struct gnet_stats_queue *q, __u32 qlen);
+void gnet_stats_add_queue(struct gnet_stats_queue *qstats,
+			  const struct gnet_stats_queue __percpu *cpu_q,
+			  const struct gnet_stats_queue *q);
+int gnet_stats_copy_app(struct gnet_dump *d, void *st, int len);
+
+int gnet_stats_finish_copy(struct gnet_dump *d);
+
+int gen_new_estimator(struct gnet_stats_basic_sync *bstats,
+		      struct gnet_stats_basic_sync __percpu *cpu_bstats,
+		      struct net_rate_estimator __rcu **rate_est,
+		      spinlock_t *lock,
+		      bool running, struct nlattr *opt);
+void gen_kill_estimator(struct net_rate_estimator __rcu **ptr);
+int gen_replace_estimator(struct gnet_stats_basic_sync *bstats,
+			  struct gnet_stats_basic_sync __percpu *cpu_bstats,
+			  struct net_rate_estimator __rcu **ptr,
+			  spinlock_t *lock,
+			  bool running, struct nlattr *opt);
+bool gen_estimator_active(struct net_rate_estimator __rcu **ptr);
+bool gen_estimator_read(struct net_rate_estimator __rcu **ptr,
+			struct gnet_stats_rate_est64 *sample);
+#endif