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, 90 insertions, 0 deletions

diff --git a/include/trace/events/sctp.h b/include/trace/events/sctp.h
new file mode 100644
index 000000000..d4aac3436
--- /dev/null
+++ b/include/trace/events/sctp.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sctp
+
+#if !defined(_TRACE_SCTP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SCTP_H
+
+#include <net/sctp/structs.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(sctp_probe_path,
+
+	TP_PROTO(struct sctp_transport *sp,
+		 const struct sctp_association *asoc),
+
+	TP_ARGS(sp, asoc),
+
+	TP_STRUCT__entry(
+		__field(__u64, asoc)
+		__field(__u32, primary)
+		__array(__u8, ipaddr, sizeof(union sctp_addr))
+		__field(__u32, state)
+		__field(__u32, cwnd)
+		__field(__u32, ssthresh)
+		__field(__u32, flight_size)
+		__field(__u32, partial_bytes_acked)
+		__field(__u32, pathmtu)
+	),
+
+	TP_fast_assign(
+		__entry->asoc = (unsigned long)asoc;
+		__entry->primary = (sp == asoc->peer.primary_path);
+		memcpy(__entry->ipaddr, &sp->ipaddr, sizeof(union sctp_addr));
+		__entry->state = sp->state;
+		__entry->cwnd = sp->cwnd;
+		__entry->ssthresh = sp->ssthresh;
+		__entry->flight_size = sp->flight_size;
+		__entry->partial_bytes_acked = sp->partial_bytes_acked;
+		__entry->pathmtu = sp->pathmtu;
+	),
+
+	TP_printk("asoc=%#llx%s ipaddr=%pISpc state=%u cwnd=%u ssthresh=%u "
+		  "flight_size=%u partial_bytes_acked=%u pathmtu=%u",
+		  __entry->asoc, __entry->primary ? "(*)" : "",
+		  __entry->ipaddr, __entry->state, __entry->cwnd,
+		  __entry->ssthresh, __entry->flight_size,
+		  __entry->partial_bytes_acked, __entry->pathmtu)
+);
+
+TRACE_EVENT(sctp_probe,
+
+	TP_PROTO(const struct sctp_endpoint *ep,
+		 const struct sctp_association *asoc,
+		 struct sctp_chunk *chunk),
+
+	TP_ARGS(ep, asoc, chunk),
+
+	TP_STRUCT__entry(
+		__field(__u64, asoc)
+		__field(__u32, mark)
+		__field(__u16, bind_port)
+		__field(__u16, peer_port)
+		__field(__u32, pathmtu)
+		__field(__u32, rwnd)
+		__field(__u16, unack_data)
+	),
+
+	TP_fast_assign(
+		struct sk_buff *skb = chunk->skb;
+
+		__entry->asoc = (unsigned long)asoc;
+		__entry->mark = skb->mark;
+		__entry->bind_port = ep->base.bind_addr.port;
+		__entry->peer_port = asoc->peer.port;
+		__entry->pathmtu = asoc->pathmtu;
+		__entry->rwnd = asoc->peer.rwnd;
+		__entry->unack_data = asoc->unack_data;
+	),
+
+	TP_printk("asoc=%#llx mark=%#x bind_port=%d peer_port=%d pathmtu=%d "
+		  "rwnd=%u unack_data=%d",
+		  __entry->asoc, __entry->mark, __entry->bind_port,
+		  __entry->peer_port, __entry->pathmtu, __entry->rwnd,
+		  __entry->unack_data)
+);
+
+#endif /* _TRACE_SCTP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>