selftest: bpf: Add test for bpf_tcp_sock() and RAW socket.

Let's extend sockopt_sk.c to cover bpf_tcp_sock() for the
wrong socket type.

Before:
  # ./test_progs -t sockopt_sk
  [  151.948613] ==================================================================
  [  151.951376] BUG: KASAN: slab-out-of-bounds in sol_tcp_sockopt+0xc7/0x8e0
  [  151.954159] Read of size 8 at addr ffff88801083d760 by task test_progs/1259
  ...
  run_test:FAIL:getsetsockopt unexpected error: -1 (errno 0)
  #427     sockopt_sk:FAIL

After:
  #427     sockopt_sk:OK

While at it, missing free() is fixed up.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20260504210610.180150-3-kuniyu@google.com

2 files changed, 32 insertions, 1 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
index 53637431ec5d..3a41c517b918 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
@@ -190,7 +190,7 @@ static int getsetsockopt(void)
 	fd = socket(AF_NETLINK, SOCK_RAW, 0);
 	if (fd < 0) {
 		log_err("Failed to create AF_NETLINK socket");
-		return -1;
+		goto err;
 	}
 
 	buf.u32 = 1;
@@ -211,6 +211,21 @@ static int getsetsockopt(void)
 	}
 	ASSERT_EQ(optlen, 8, "Unexpected NETLINK_LIST_MEMBERSHIPS value");
 
+	/* Trick bpf_tcp_sock() with IPPROTO_TCP */
+	close(fd);
+	fd = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
+	if (!ASSERT_OK_FD(fd, "socket"))
+		goto err;
+
+	/* The BPF prog intercepts this before the kernel sees it, any
+	 * optlen works. Go with 4 bytes for simplicity.
+	 */
+	buf.u32 = 1;
+	optlen = sizeof(buf.u32);
+	err = setsockopt(fd, SOL_TCP, TCP_SAVED_SYN, &buf, optlen);
+	if (!ASSERT_ERR(err, "setsockopt(TCP_SAVED_SYN)"))
+		goto err;
+
 	free(big_buf);
 	close(fd);
 	return 0;
diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c b/tools/testing/selftests/bpf/progs/sockopt_sk.c
index cb990a7d3d45..5e0b27e7855c 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -149,6 +149,20 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	if (sk && sk->family == AF_NETLINK)
 		goto out;
 
+	if (sk && sk->family == AF_INET && sk->type == SOCK_RAW) {
+		struct bpf_tcp_sock *tp = bpf_tcp_sock(sk);
+
+		if (tp) {
+			char saved_syn[60];
+
+			bpf_getsockopt(sk, SOL_TCP, TCP_SAVED_SYN,
+				       &saved_syn, sizeof(saved_syn));
+			goto consumed;
+		}
+
+		goto out;
+	}
+
 	/* Make sure bpf_get_netns_cookie is callable.
 	 */
 	if (bpf_get_netns_cookie(NULL) == 0)
@@ -224,6 +238,8 @@ int _setsockopt(struct bpf_sockopt *ctx)
 		return 0; /* couldn't get sk storage */
 
 	storage->val = optval[0];
+
+consumed:
 	ctx->optlen = -1; /* BPF has consumed this option, don't call kernel
 			   * setsockopt handler.
 			   */