Merge pull request #12024 from poettering/bindtoifindex

use SO_BINDTOIFINDEX where appropriate

src/basic/missing_socket.h

@@ -32,6 +32,10 @@ struct sockaddr_vm {
 #define SO_PEERGROUPS 59
 #endif
 
+#ifndef SO_BINDTOIFINDEX
+#define SO_BINDTOIFINDEX 62
+#endif
+
 #ifndef SOL_NETLINK
 #define SOL_NETLINK 270
 #endif

src/basic/socket-label.c

@@ -68,9 +68,11 @@ int socket_address_listen(
         }
 
         if (IN_SET(socket_address_family(a), AF_INET, AF_INET6)) {
-                if (bind_to_device)
-                        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, bind_to_device, strlen(bind_to_device)+1) < 0)
-                                return -errno;
+                if (bind_to_device) {
+                        r = socket_bind_to_ifname(fd, bind_to_device);
+                        if (r < 0)
+                                return r;
+                }
 
                 if (reuse_port) {
                         r = setsockopt_int(fd, SOL_SOCKET, SO_REUSEPORT, true);

src/basic/socket-util.c

@@ -1354,3 +1354,39 @@ int sockaddr_un_set_path(struct sockaddr_un *ret, const char *path) {
                 return (int) (offsetof(struct sockaddr_un, sun_path) + l + 1); /* include trailing NUL in size */
         }
 }
+
+int socket_bind_to_ifname(int fd, const char *ifname) {
+        assert(fd >= 0);
+
+        /* Call with NULL to drop binding */
+
+        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen_ptr(ifname)) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int socket_bind_to_ifindex(int fd, int ifindex) {
+        char ifname[IFNAMSIZ] = "";
+
+        assert(fd >= 0);
+
+        if (ifindex <= 0) {
+                /* Drop binding */
+                if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, NULL, 0) < 0)
+                        return -errno;
+
+                return 0;
+        }
+
+        if (setsockopt(fd, SOL_SOCKET, SO_BINDTOIFINDEX, &ifindex, sizeof(ifindex)) >= 0)
+                return 0;
+        if (errno != ENOPROTOOPT)
+                return -errno;
+
+        /* Fall back to SO_BINDTODEVICE on kernels < 5.0 which didn't have SO_BINDTOIFINDEX */
+        if (!if_indextoname(ifindex, ifname))
+                return -errno;
+
+        return socket_bind_to_ifname(fd, ifname);
+}

src/basic/socket-util.h

@@ -198,3 +198,6 @@ static inline int setsockopt_int(int fd, int level, int optname, int value) {
 
         return 0;
 }
+
+int socket_bind_to_ifname(int fd, const char *ifname);
+int socket_bind_to_ifindex(int fd, int ifindex);