selftests/bpf: Tests for BPF_SK_LOOKUP attach point

Add tests to test_progs that exercise:

 - attaching/detaching/querying programs to BPF_SK_LOOKUP hook,
 - redirecting socket lookup to a socket selected by BPF program,
 - failing a socket lookup on BPF program's request,
 - error scenarios for selecting a socket from BPF program,
 - accessing BPF program context,
 - attaching and running multiple BPF programs.

Run log:

  bash-5.0# ./test_progs -n 70
  #70/1 query lookup prog:OK
  #70/2 TCP IPv4 redir port:OK
  #70/3 TCP IPv4 redir addr:OK
  #70/4 TCP IPv4 redir with reuseport:OK
  #70/5 TCP IPv4 redir skip reuseport:OK
  #70/6 TCP IPv6 redir port:OK
  #70/7 TCP IPv6 redir addr:OK
  #70/8 TCP IPv4->IPv6 redir port:OK
  #70/9 TCP IPv6 redir with reuseport:OK
  #70/10 TCP IPv6 redir skip reuseport:OK
  #70/11 UDP IPv4 redir port:OK
  #70/12 UDP IPv4 redir addr:OK
  #70/13 UDP IPv4 redir with reuseport:OK
  #70/14 UDP IPv4 redir skip reuseport:OK
  #70/15 UDP IPv6 redir port:OK
  #70/16 UDP IPv6 redir addr:OK
  #70/17 UDP IPv4->IPv6 redir port:OK
  #70/18 UDP IPv6 redir and reuseport:OK
  #70/19 UDP IPv6 redir skip reuseport:OK
  #70/20 TCP IPv4 drop on lookup:OK
  #70/21 TCP IPv6 drop on lookup:OK
  #70/22 UDP IPv4 drop on lookup:OK
  #70/23 UDP IPv6 drop on lookup:OK
  #70/24 TCP IPv4 drop on reuseport:OK
  #70/25 TCP IPv6 drop on reuseport:OK
  #70/26 UDP IPv4 drop on reuseport:OK
  #70/27 TCP IPv6 drop on reuseport:OK
  #70/28 sk_assign returns EEXIST:OK
  #70/29 sk_assign honors F_REPLACE:OK
  #70/30 sk_assign accepts NULL socket:OK
  #70/31 access ctx->sk:OK
  #70/32 narrow access to ctx v4:OK
  #70/33 narrow access to ctx v6:OK
  #70/34 sk_assign rejects TCP established:OK
  #70/35 sk_assign rejects UDP connected:OK
  #70/36 multi prog - pass, pass:OK
  #70/37 multi prog - drop, drop:OK
  #70/38 multi prog - pass, drop:OK
  #70/39 multi prog - drop, pass:OK
  #70/40 multi prog - pass, redir:OK
  #70/41 multi prog - redir, pass:OK
  #70/42 multi prog - drop, redir:OK
  #70/43 multi prog - redir, drop:OK
  #70/44 multi prog - redir, redir:OK
  #70 sk_lookup:OK
  Summary: 1/44 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200717103536.397595-16-jakub@cloudflare.com

tools/testing/selftests/bpf/network_helpers.c

@@ -73,29 +73,8 @@ int start_server(int family, int type, const char *addr_str, __u16 port,
 	socklen_t len;
 	int fd;
 
-	if (family == AF_INET) {
-		struct sockaddr_in *sin = (void *)&addr;
-
-		sin->sin_family = AF_INET;
-		sin->sin_port = htons(port);
-		if (addr_str &&
-		    inet_pton(AF_INET, addr_str, &sin->sin_addr) != 1) {
-			log_err("inet_pton(AF_INET, %s)", addr_str);
+	if (make_sockaddr(family, addr_str, port, &addr, &len))
 		return -1;
-		}
-		len = sizeof(*sin);
-	} else {
-		struct sockaddr_in6 *sin6 = (void *)&addr;
-
-		sin6->sin6_family = AF_INET6;
-		sin6->sin6_port = htons(port);
-		if (addr_str &&
-		    inet_pton(AF_INET6, addr_str, &sin6->sin6_addr) != 1) {
-			log_err("inet_pton(AF_INET6, %s)", addr_str);
-			return -1;
-		}
-		len = sizeof(*sin6);
-	}
 
 	fd = socket(family, type, 0);
 	if (fd < 0) {
@@ -194,3 +173,36 @@ int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms)
 
 	return 0;
 }
+
+int make_sockaddr(int family, const char *addr_str, __u16 port,
+		  struct sockaddr_storage *addr, socklen_t *len)
+{
+	if (family == AF_INET) {
+		struct sockaddr_in *sin = (void *)addr;
+
+		sin->sin_family = AF_INET;
+		sin->sin_port = htons(port);
+		if (addr_str &&
+		    inet_pton(AF_INET, addr_str, &sin->sin_addr) != 1) {
+			log_err("inet_pton(AF_INET, %s)", addr_str);
+			return -1;
+		}
+		if (len)
+			*len = sizeof(*sin);
+		return 0;
+	} else if (family == AF_INET6) {
+		struct sockaddr_in6 *sin6 = (void *)addr;
+
+		sin6->sin6_family = AF_INET6;
+		sin6->sin6_port = htons(port);
+		if (addr_str &&
+		    inet_pton(AF_INET6, addr_str, &sin6->sin6_addr) != 1) {
+			log_err("inet_pton(AF_INET6, %s)", addr_str);
+			return -1;
+		}
+		if (len)
+			*len = sizeof(*sin6);
+		return 0;
+	}
+	return -1;
+}

tools/testing/selftests/bpf/network_helpers.h

@@ -37,5 +37,7 @@ int start_server(int family, int type, const char *addr, __u16 port,
 		 int timeout_ms);
 int connect_to_fd(int server_fd, int timeout_ms);
 int connect_fd_to_fd(int client_fd, int server_fd, int timeout_ms);
+int make_sockaddr(int family, const char *addr_str, __u16 port,
+		  struct sockaddr_storage *addr, socklen_t *len);
 
 #endif