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, 82 insertions, 0 deletions

diff --git a/include/net/inet_common.h b/include/net/inet_common.h
new file mode 100644
index 000000000..3d747896b
--- /dev/null
+++ b/include/net/inet_common.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _INET_COMMON_H
+#define _INET_COMMON_H
+
+#include <linux/indirect_call_wrapper.h>
+#include <linux/net.h>
+#include <linux/netdev_features.h>
+#include <linux/types.h>
+#include <net/sock.h>
+
+extern const struct proto_ops inet_stream_ops;
+extern const struct proto_ops inet_dgram_ops;
+
+/*
+ *	INET4 prototypes used by INET6
+ */
+
+struct msghdr;
+struct net;
+struct page;
+struct sock;
+struct socket;
+
+int inet_release(struct socket *sock);
+int inet_stream_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
+			int addr_len, int flags);
+int __inet_stream_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
+			  int addr_len, int flags, int is_sendmsg);
+int inet_dgram_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
+		       int addr_len, int flags);
+int inet_accept(struct socket *sock, struct socket *newsock,
+		struct proto_accept_arg *arg);
+void __inet_accept(struct socket *sock, struct socket *newsock,
+		   struct sock *newsk);
+int inet_send_prepare(struct sock *sk);
+int inet_sendmsg(struct socket *sock, struct msghdr *msg, size_t size);
+void inet_splice_eof(struct socket *sock);
+int inet_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+		 int flags);
+int inet_shutdown(struct socket *sock, int how);
+int inet_listen(struct socket *sock, int backlog);
+int __inet_listen_sk(struct sock *sk, int backlog);
+void inet_sock_destruct(struct sock *sk);
+int inet_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int addr_len);
+int inet_bind_sk(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len);
+/* Don't allocate port at this moment, defer to connect. */
+#define BIND_FORCE_ADDRESS_NO_PORT	(1 << 0)
+/* Grab and release socket lock. */
+#define BIND_WITH_LOCK			(1 << 1)
+/* Called from BPF program. */
+#define BIND_FROM_BPF			(1 << 2)
+/* Skip CAP_NET_BIND_SERVICE check. */
+#define BIND_NO_CAP_NET_BIND_SERVICE	(1 << 3)
+int __inet_bind(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len,
+		u32 flags);
+int inet_getname(struct socket *sock, struct sockaddr *uaddr,
+		 int peer);
+int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
+int inet_ctl_sock_create(struct sock **sk, unsigned short family,
+			 unsigned short type, unsigned char protocol,
+			 struct net *net);
+int inet_recv_error(struct sock *sk, struct msghdr *msg, int len);
+
+struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb);
+int inet_gro_complete(struct sk_buff *skb, int nhoff);
+struct sk_buff *inet_gso_segment(struct sk_buff *skb,
+				 netdev_features_t features);
+
+static inline void inet_ctl_sock_destroy(struct sock *sk)
+{
+	if (sk)
+		sock_release(sk->sk_socket);
+}
+
+#define indirect_call_gro_receive(f2, f1, cb, head, skb)	\
+({								\
+	unlikely(gro_recursion_inc_test(skb)) ?			\
+		NAPI_GRO_CB(skb)->flush |= 1, NULL :		\
+		INDIRECT_CALL_2(cb, f2, f1, head, skb);		\
+})
+
+#endif