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, 62 insertions, 0 deletions

diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
new file mode 100644
index 000000000..c3e5d9fa6
--- /dev/null
+++ b/drivers/scsi/iscsi_tcp.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * iSCSI Initiator TCP Transport
+ * Copyright (C) 2004 Dmitry Yusupov
+ * Copyright (C) 2004 Alex Aizman
+ * Copyright (C) 2005 - 2006 Mike Christie
+ * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
+ * maintained by open-iscsi@googlegroups.com
+ *
+ * See the file COPYING included with this distribution for more details.
+ */
+
+#ifndef ISCSI_SW_TCP_H
+#define ISCSI_SW_TCP_H
+
+#include <scsi/libiscsi.h>
+#include <scsi/libiscsi_tcp.h>
+
+struct socket;
+struct iscsi_tcp_conn;
+
+/* Socket connection send helper */
+struct iscsi_sw_tcp_send {
+	struct iscsi_hdr	*hdr;
+	struct iscsi_segment	segment;
+	struct iscsi_segment	data_segment;
+};
+
+struct iscsi_sw_tcp_conn {
+	struct socket		*sock;
+	/* Taken when accessing the sock from the netlink/sysfs interface */
+	struct mutex		sock_lock;
+
+	struct work_struct	recvwork;
+	bool			queue_recv;
+
+	struct iscsi_sw_tcp_send out;
+	/* old values for socket callbacks */
+	void			(*old_data_ready)(struct sock *);
+	void			(*old_state_change)(struct sock *);
+	void			(*old_write_space)(struct sock *);
+
+	/* data and header digests */
+	u32			tx_crc;	/* CRC32C (Tx) */
+	u32			rx_crc;	/* CRC32C (Rx) */
+
+	/* MIB custom statistics */
+	uint32_t		sendpage_failures_cnt;
+	uint32_t		discontiguous_hdr_cnt;
+};
+
+struct iscsi_sw_tcp_host {
+	struct iscsi_session	*session;
+};
+
+struct iscsi_sw_tcp_hdrbuf {
+	struct iscsi_hdr	hdrbuf;
+	char			hdrextbuf[ISCSI_MAX_AHS_SIZE +
+		                                  ISCSI_DIGEST_SIZE];
+};
+
+#endif /* ISCSI_SW_TCP_H */