bpf, sockmap: Build helper to create connected socket pair

A common operation for testing is to spin up a pair of sockets that are
connected. Then we can use these to run specific tests that need to
send data, check BPF programs and so on.

The sockmap_listen programs already have this logic lets move it into
the new sockmap_helpers header file for general use.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20230523025618.113937-11-john.fastabend@gmail.com

1 files changed, 118 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h b/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
index 5aa99e6adcb4..d12665490a90 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
@@ -269,4 +269,122 @@ static inline struct sockaddr *sockaddr(struct sockaddr_storage *ss)
 	return (struct sockaddr *)ss;
 }
 
+static inline int add_to_sockmap(int sock_mapfd, int fd1, int fd2)
+{
+	u64 value;
+	u32 key;
+	int err;
+
+	key = 0;
+	value = fd1;
+	err = xbpf_map_update_elem(sock_mapfd, &key, &value, BPF_NOEXIST);
+	if (err)
+		return err;
+
+	key = 1;
+	value = fd2;
+	return xbpf_map_update_elem(sock_mapfd, &key, &value, BPF_NOEXIST);
+}
+
+static inline int create_pair(int s, int family, int sotype, int *c, int *p)
+{
+	struct sockaddr_storage addr;
+	socklen_t len;
+	int err = 0;
+
+	len = sizeof(addr);
+	err = xgetsockname(s, sockaddr(&addr), &len);
+	if (err)
+		return err;
+
+	*c = xsocket(family, sotype, 0);
+	if (*c < 0)
+		return errno;
+	err = xconnect(*c, sockaddr(&addr), len);
+	if (err) {
+		err = errno;
+		goto close_cli0;
+	}
+
+	*p = xaccept_nonblock(s, NULL, NULL);
+	if (*p < 0) {
+		err = errno;
+		goto close_cli0;
+	}
+	return err;
+close_cli0:
+	close(*c);
+	return err;
+}
+
+static inline int create_socket_pairs(int s, int family, int sotype,
+				      int *c0, int *c1, int *p0, int *p1)
+{
+	int err;
+
+	err = create_pair(s, family, sotype, c0, p0);
+	if (err)
+		return err;
+
+	err = create_pair(s, family, sotype, c1, p1);
+	if (err) {
+		close(*c0);
+		close(*p0);
+	}
+	return err;
+}
+
+static inline int enable_reuseport(int s, int progfd)
+{
+	int err, one = 1;
+
+	err = xsetsockopt(s, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+	if (err)
+		return -1;
+	err = xsetsockopt(s, SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF, &progfd,
+			  sizeof(progfd));
+	if (err)
+		return -1;
+
+	return 0;
+}
+
+static inline int socket_loopback_reuseport(int family, int sotype, int progfd)
+{
+	struct sockaddr_storage addr;
+	socklen_t len;
+	int err, s;
+
+	init_addr_loopback(family, &addr, &len);
+
+	s = xsocket(family, sotype, 0);
+	if (s == -1)
+		return -1;
+
+	if (progfd >= 0)
+		enable_reuseport(s, progfd);
+
+	err = xbind(s, sockaddr(&addr), len);
+	if (err)
+		goto close;
+
+	if (sotype & SOCK_DGRAM)
+		return s;
+
+	err = xlisten(s, SOMAXCONN);
+	if (err)
+		goto close;
+
+	return s;
+close:
+	xclose(s);
+	return -1;
+}
+
+static inline int socket_loopback(int family, int sotype)
+{
+	return socket_loopback_reuseport(family, sotype, -1);
+}
+
+
 #endif // __SOCKMAP_HELPERS__