selftests/bpf: Test packet range of pointers sharing an idgrafted

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/include/net/netevent.h b/include/net/netevent.h
new file mode 100644
index 000000000..1be3757a8
--- /dev/null
+++ b/include/net/netevent.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NET_EVENT_H
+#define _NET_EVENT_H
+
+/*
+ *	Generic netevent notifiers
+ *
+ *	Authors:
+ *      Tom Tucker              <tom@opengridcomputing.com>
+ *      Steve Wise              <swise@opengridcomputing.com>
+ *
+ * 	Changes:
+ */
+
+struct dst_entry;
+struct neighbour;
+struct notifier_block ;
+
+struct netevent_redirect {
+	struct dst_entry *old;
+	struct dst_entry *new;
+	struct neighbour *neigh;
+	const void *daddr;
+};
+
+enum netevent_notif_type {
+	NETEVENT_NEIGH_UPDATE = 1, /* arg is struct neighbour ptr */
+	NETEVENT_REDIRECT,	   /* arg is struct netevent_redirect ptr */
+	NETEVENT_DELAY_PROBE_TIME_UPDATE, /* arg is struct neigh_parms ptr */
+	NETEVENT_IPV4_MPATH_HASH_UPDATE, /* arg is struct net ptr */
+	NETEVENT_IPV6_MPATH_HASH_UPDATE, /* arg is struct net ptr */
+	NETEVENT_IPV4_FWD_UPDATE_PRIORITY_UPDATE, /* arg is struct net ptr */
+};
+
+int register_netevent_notifier(struct notifier_block *nb);
+int unregister_netevent_notifier(struct notifier_block *nb);
+int call_netevent_notifiers(unsigned long val, void *v);
+
+#endif