fix(driver): round of small fixes and improvements around unix socket…

… paths handling in drivers.

Signed-off-by: Federico Di Pierro <[email protected]>

driver/bpf/filler_helpers.h

@@ -420,14 +420,22 @@ static __always_inline bool bpf_getsockname(struct socket *sock,
 		struct unix_sock *u;
 		struct unix_address *addr;
 
-		if(peer)
+		if(peer) {
 			sk = _READ(((struct unix_sock *)sk)->peer);
+			if(!sk) {
+				return false;
+			}
+		}
 
 		u = (struct unix_sock *)sk;
 		addr = _READ(u->addr);
 		if(!addr) {
 			sunaddr->sun_family = AF_UNIX;
 			sunaddr->sun_path[0] = 0;
+			// The first byte to 0 can be confused with an `abstract socket address` for this reason
+			// we put also the second byte to 0 to comunicate to the caller that the address is not
+			// valid.
+			sunaddr->sun_path[1] = 0;
 		} else {
 			unsigned int len = _READ(addr->len);
 
@@ -897,13 +905,11 @@ static __always_inline long bpf_fd_to_socktuple(struct filler_data *data,
 			us_name = ((struct sockaddr_un *)peer_address)->sun_path;
 		}
 
-		size = 1 + 8 + 8;
 		int res = unix_socket_path(
 		        &data->buf[(data->state->tail_ctx.curoff + 1 + 8 + 8) & SCRATCH_SIZE_HALF],
 		        us_name,
 		        UNIX_PATH_MAX);
-		size += res;
-
+		size = 1 + 8 + 8 + res;
 		break;
 	}
 	}

driver/modern_bpf/helpers/store/auxmap_store_params.h

@@ -776,7 +776,7 @@ static __always_inline void auxmap__store_socktuple_param(struct auxiliary_map *
 
 	case AF_UNIX: {
 		struct unix_sock *socket_local = (struct unix_sock *)sk;
-		struct unix_sock *socket_remote = (struct unix_sock *)BPF_CORE_READ(socket_local, peer);
+		struct unix_sock *socket_peer = (struct unix_sock *)BPF_CORE_READ(socket_local, peer);
 		char *path = NULL;
 
 		/* Pack the tuple info:
@@ -787,18 +787,16 @@ static __always_inline void auxmap__store_socktuple_param(struct auxiliary_map *
 		 */
 		push__u8(auxmap->data, &auxmap->payload_pos, socket_family_to_scap(socket_family));
 		if(direction == OUTBOUND) {
-			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_remote);
+			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_peer);
 			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_local);
-			path = BPF_CORE_READ(socket_remote, addr, name[0].sun_path);
+			path = BPF_CORE_READ(socket_peer, addr, name[0].sun_path);  // empty
 		} else {
 			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_local);
-			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_remote);
+			push__u64(auxmap->data, &auxmap->payload_pos, (uint64_t)socket_peer);
 			path = BPF_CORE_READ(socket_local, addr, name[0].sun_path);
 		}
 
-		unsigned long start_reading_point;
-		char first_path_byte = *(char *)path;
-		if(first_path_byte == '\0') {
+		if(path[0] == '\0') {
 			/* Please note exceptions in the `sun_path`:
 			 * Taken from: https://man7.org/linux/man-pages/man7/unix.7.html
 			 *
@@ -808,14 +806,12 @@ static __always_inline void auxmap__store_socktuple_param(struct auxiliary_map *
 			 *
 			 * So in this case, we need to skip the initial `\0`.
 			 */
-			start_reading_point = (unsigned long)path + 1;
-		} else {
-			start_reading_point = (unsigned long)path;
+			path++;
 		}
 
 		uint16_t written_bytes = push__charbuf(auxmap->data,
 		                                       &auxmap->payload_pos,
-		                                       start_reading_point,
+		                                       (unsigned long)path,
 		                                       MAX_UNIX_SOCKET_PATH,
 		                                       KERNEL);
 		final_param_len = FAMILY_SIZE + KERNEL_POINTER + KERNEL_POINTER + written_bytes;

driver/ppm_events.c

@@ -861,6 +861,11 @@ static struct socket *ppm_sockfd_lookup_light(int fd, int *err, int *fput_needed
 */
 
 static void unix_socket_path(char *dest, const char *path, size_t size) {
+	if(path == NULL) {
+		dest[0] = '\0';
+		return;
+	}
+
 	if(path[0] == '\0') {
 		/* Please note exceptions in the `sun_path`:
 		 * Taken from: https://man7.org/linux/man-pages/man7/unix.7.html
@@ -1173,7 +1178,8 @@ uint16_t fd_to_socktuple(int fd,
 		} else {
 			*(uint64_t *)(targetbuf + 1) = (uint64_t)(unsigned long)speer;
 			*(uint64_t *)(targetbuf + 1 + 8) = (uint64_t)(unsigned long)us;
-			sock_getname(sock, (struct sockaddr *)&peer_address, 1);
+			err = sock_getname(sock, (struct sockaddr *)&peer_address, 1);
+			ASSERT(err == 0);
 			us_name = ((struct sockaddr_un *)&peer_address)->sun_path;
 		}
 

test/libsinsp_e2e/unix_udp_client_server.cpp

@@ -57,8 +57,8 @@ class unix_udp_server {
 
 	void run() {
 		int sock;
-		struct sockaddr_un name;
-		struct sockaddr_un caddr;
+		struct sockaddr_un name = {};
+		struct sockaddr_un caddr = {};
 		socklen_t address_length = sizeof(struct sockaddr_un);
 		char buf[1024];
 
@@ -122,7 +122,7 @@ class unix_udp_client {
 public:
 	void run() {
 		int sock;
-		struct sockaddr_un name;
+		struct sockaddr_un name = {};
 
 		/* Create socket on which to send. */
 		sock = socket(AF_UNIX, SOCK_DGRAM, 0);