wg: Add support to set bind-dev on Linux

src/config.c

@@ -104,6 +104,30 @@ static inline bool parse_fwmark(uint32_t *fwmark, uint32_t *flags, const char *v
 	return false;
 }
 
+#ifdef __linux__
+static inline bool parse_bind_dev(uint32_t *bind_dev, char *bind_dev_name, uint32_t *flags, const char *value)
+{
+	if (strlen (value) > IFNAMSIZ) {
+		fprintf(stderr, "BindDev must be shorter or equal to %d chars, found: '%s'\n", IFNAMSIZ, value);
+		return false;
+	}
+
+	snprintf(bind_dev_name, IFNAMSIZ, "%s", value);
+	unsigned int i = if_nametoindex(value);
+	if (errno) {
+		fprintf(stderr, "Failed to get ifIndex for BindDev '%s': %s\n", value, strerror(errno));
+		return false;
+	}
+
+	*flags |= WGDEVICE_HAS_BIND_DEV;
+	*bind_dev = (int) i;
+
+	printf ("bind-dev %s translates to %d\n", value, i);
+
+	return true;
+}
+#endif
+
 static inline bool parse_key(uint8_t key[static WG_KEY_LEN], const char *value)
 {
 	if (!key_from_base64(key, value)) {
@@ -446,6 +470,10 @@ static bool process_line(struct config_ctx *ctx, const char *line)
 			ret = parse_port(&ctx->device->listen_port, &ctx->device->flags, value);
 		else if (key_match("FwMark"))
 			ret = parse_fwmark(&ctx->device->fwmark, &ctx->device->flags, value);
+#ifdef __linux__
+		else if (key_match("BindDev"))
+			ret = parse_bind_dev(&ctx->device->bind_dev, (char *) &ctx->device->bind_dev_name, &ctx->device->flags, value);
+#endif
 		else if (key_match("PrivateKey")) {
 			ret = parse_key(ctx->device->private_key, value);
 			if (ret)
@@ -582,6 +610,13 @@ struct wgdevice *config_read_cmd(const char *argv[], int argc)
 				goto error;
 			argv += 2;
 			argc -= 2;
+#ifdef __linux__
+		} else if (!strcmp(argv[0], "bind-dev") && argc >= 2 && !peer) {
+			if (!parse_bind_dev(&device->bind_dev, (char *) device->bind_dev_name, &device->flags, argv[1]))
+				goto error;
+			argv += 2;
+			argc -= 2;
+#endif
 		} else if (!strcmp(argv[0], "private-key") && argc >= 2 && !peer) {
 			if (!parse_keyfile(device->private_key, argv[1]))
 				goto error;

src/containers.h

@@ -71,7 +71,8 @@ enum {
 	WGDEVICE_HAS_PRIVATE_KEY = 1U << 1,
 	WGDEVICE_HAS_PUBLIC_KEY = 1U << 2,
 	WGDEVICE_HAS_LISTEN_PORT = 1U << 3,
-	WGDEVICE_HAS_FWMARK = 1U << 4
+	WGDEVICE_HAS_FWMARK = 1U << 4,
+	WGDEVICE_HAS_BIND_DEV = 1U << 5
 };
 
 struct wgdevice {
@@ -87,6 +88,9 @@ struct wgdevice {
 	uint16_t listen_port;
 
 	struct wgpeer *first_peer, *last_peer;
+
+	uint32_t bind_dev;
+	char bind_dev_name[IFNAMSIZ];
 };
 
 #define for_each_wgpeer(__dev, __peer) for ((__peer) = (__dev)->first_peer; (__peer); (__peer) = (__peer)->next_peer)

src/ipc-linux.h

@@ -32,6 +32,15 @@ struct interface {
 	bool is_wireguard;
 };
 
+static void get_bind_dev_name(char *ifname, const int ifindex)
+{
+       if_indextoname (ifindex, ifname);
+       if (errno) {
+               fprintf(stderr, "Failed to get interface name for BindDev with ID '%d': %s\n", ifindex, strerror(errno));
+               ifname = "ERROR";
+       }
+}
+
 static int parse_linkinfo(const struct nlattr *attr, void *data)
 {
 	struct interface *interface = data;
@@ -165,6 +174,8 @@ static int kernel_set_device(struct wgdevice *dev)
 			mnl_attr_put_u16(nlh, WGDEVICE_A_LISTEN_PORT, dev->listen_port);
 		if (dev->flags & WGDEVICE_HAS_FWMARK)
 			mnl_attr_put_u32(nlh, WGDEVICE_A_FWMARK, dev->fwmark);
+		if (dev->flags & WGDEVICE_HAS_BIND_DEV)
+			mnl_attr_put_u32(nlh, WGDEVICE_A_BIND_IFINDEX, dev->bind_dev);
 		if (dev->flags & WGDEVICE_REPLACE_PEERS)
 			flags |= WGDEVICE_F_REPLACE_PEERS;
 		if (flags)
@@ -439,6 +450,15 @@ static int parse_device(const struct nlattr *attr, void *data)
 		if (!mnl_attr_validate(attr, MNL_TYPE_U32))
 			device->fwmark = mnl_attr_get_u32(attr);
 		break;
+	case WGDEVICE_A_BIND_IFINDEX:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U32)) {
+			device->bind_dev = mnl_attr_get_u32(attr);
+			if (device->bind_dev) {
+				device->flags |= WGDEVICE_HAS_BIND_DEV;
+				get_bind_dev_name(device->bind_dev_name, device->bind_dev);
+			}
+		}
+		break;
 	case WGDEVICE_A_PEERS:
 		return mnl_attr_parse_nested(attr, parse_peers, device);
 	}

src/man/wg.8

@@ -36,7 +36,7 @@ Sub-commands that take an INTERFACE must be passed a WireGuard interface.
 .SH COMMANDS
 
 .TP
-\fBshow\fP { \fI<interface>\fP | \fIall\fP | \fIinterfaces\fP } [\fIpublic-key\fP | \fIprivate-key\fP | \fIlisten-port\fP | \fIfwmark\fP | \fIpeers\fP | \fIpreshared-keys\fP | \fIendpoints\fP | \fIallowed-ips\fP | \fIlatest-handshakes\fP | \fIpersistent-keepalive\fP | \fItransfer\fP | \fIdump\fP]
+\fBshow\fP { \fI<interface>\fP | \fIall\fP | \fIinterfaces\fP } [\fIpublic-key\fP | \fIprivate-key\fP | \fIlisten-port\fP | \fIbind-dev\fP | \fIfwmark\fP | \fIpeers\fP | \fIpreshared-keys\fP | \fIendpoints\fP | \fIallowed-ips\fP | \fIlatest-handshakes\fP | \fIpersistent-keepalive\fP | \fItransfer\fP | \fIdump\fP]
 Shows current WireGuard configuration and runtime information of specified \fI<interface>\fP.
 If no \fI<interface>\fP is specified, \fI<interface>\fP defaults to \fIall\fP.
 If \fIinterfaces\fP is specified, prints a list of all WireGuard interfaces,
@@ -55,7 +55,7 @@ transfer-rx, transfer-tx, persistent-keepalive.
 Shows the current configuration of \fI<interface>\fP in the format described
 by \fICONFIGURATION FILE FORMAT\fP below.
 .TP
-\fBset\fP \fI<interface>\fP [\fIlisten-port\fP \fI<port>\fP] [\fIfwmark\fP \fI<fwmark>\fP] [\fIprivate-key\fP \fI<file-path>\fP] [\fIpeer\fP \fI<base64-public-key>\fP [\fIremove\fP] [\fIpreshared-key\fP \fI<file-path>\fP] [\fIendpoint\fP \fI<ip>:<port>\fP] [\fIpersistent-keepalive\fP \fI<interval seconds>\fP] [\fIallowed-ips\fP \fI<ip1>/<cidr1>\fP[,\fI<ip2>/<cidr2>\fP]...] ]...
+\fBset\fP \fI<interface>\fP [\fIlisten-port\fP \fI<port>\fP] [\fIbind-dev\fP \fI<bind-dev>\fP] [\fIfwmark\fP \fI<fwmark>\fP] [\fIprivate-key\fP \fI<file-path>\fP] [\fIpeer\fP \fI<base64-public-key>\fP [\fIremove\fP] [\fIpreshared-key\fP \fI<file-path>\fP] [\fIendpoint\fP \fI<ip>:<port>\fP] [\fIpersistent-keepalive\fP \fI<interval seconds>\fP] [\fIallowed-ips\fP \fI<ip1>/<cidr1>\fP[,\fI<ip2>/<cidr2>\fP]...] ]...
 Sets configuration values for the specified \fI<interface>\fP. Multiple
 \fIpeer\fPs may be specified, and if the \fIremove\fP argument is given
 for a peer, that peer is removed, not configured. If \fIlisten-port\fP
@@ -137,6 +137,9 @@ PrivateKey \(em a base64 private key generated by \fIwg genkey\fP. Required.
 ListenPort \(em a 16-bit port for listening. Optional; if not specified, chosen
 randomly.
 .IP \(bu
+BindDev \(em an interface to bind the listening/sending UDP socket to. This can be
+use to make Wireguard send/receive encrypted packets via a VRF on Linux. Optional.
+.IP \(bu
 FwMark \(em a 32-bit fwmark for outgoing packets. If set to 0 or "off", this
 option is disabled. May be specified in hexadecimal by prepending "0x". Optional.
 .P

src/set.c

@@ -18,7 +18,7 @@ int set_main(int argc, const char *argv[])
 	int ret = 1;
 
 	if (argc < 3) {
-		fprintf(stderr, "Usage: %s %s <interface> [listen-port <port>] [fwmark <mark>] [private-key <file path>] [peer <base64 public key> [remove] [preshared-key <file path>] [endpoint <ip>:<port>] [persistent-keepalive <interval seconds>] [allowed-ips <ip1>/<cidr1>[,<ip2>/<cidr2>]...] ]...\n", PROG_NAME, argv[0]);
+		fprintf(stderr, "Usage: %s %s <interface> [listen-port <port>] [bind-dev <interface>] [fwmark <mark>] [private-key <file path>] [peer <base64 public key> [remove] [preshared-key <file path>] [endpoint <ip>:<port>] [persistent-keepalive <interval seconds>] [allowed-ips <ip1>/<cidr1>[,<ip2>/<cidr2>]...] ]...\n", PROG_NAME, argv[0]);
 		return 1;
 	}
 

src/show.c

@@ -202,7 +202,7 @@ static char *bytes(uint64_t b)
 static const char *COMMAND_NAME;
 static void show_usage(void)
 {
-	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | listen-port | fwmark | peers | preshared-keys | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive | dump]\n", PROG_NAME, COMMAND_NAME);
+	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | listen-port | bind-dev | fwmark | peers | preshared-keys | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive | dump]\n", PROG_NAME, COMMAND_NAME);
 }
 
 static void pretty_print(struct wgdevice *device)
@@ -220,6 +220,8 @@ static void pretty_print(struct wgdevice *device)
 		terminal_printf("  " TERMINAL_BOLD "listening port" TERMINAL_RESET ": %u\n", device->listen_port);
 	if (device->fwmark)
 		terminal_printf("  " TERMINAL_BOLD "fwmark" TERMINAL_RESET ": 0x%x\n", device->fwmark);
+	if (device->bind_dev)
+		terminal_printf("  " TERMINAL_BOLD "bind dev" TERMINAL_RESET ": %s\n", device->bind_dev_name);
 	if (device->first_peer) {
 		sort_peers(device);
 		terminal_printf("\n");
@@ -261,7 +263,11 @@ static void dump_print(struct wgdevice *device, bool with_interface)
 	printf("%s\t", maybe_key(device->public_key, device->flags & WGDEVICE_HAS_PUBLIC_KEY));
 	printf("%u\t", device->listen_port);
 	if (device->fwmark)
-		printf("0x%x\n", device->fwmark);
+		printf("0x%x\t", device->fwmark);
+	else
+		printf("off\t");
+	if (device->bind_dev)
+		printf("%s\n", device->bind_dev_name);
 	else
 		printf("off\n");
 	for_each_wgpeer(device, peer) {
@@ -311,6 +317,17 @@ static bool ugly_print(struct wgdevice *device, const char *param, bool with_int
 			printf("0x%x\n", device->fwmark);
 		else
 			printf("off\n");
+	} else if (!strcmp(param, "bind-dev")) {
+		if (with_interface)
+			printf("%s\t", device->name);
+#ifdef __linux__
+		if (device->bind_dev)
+			printf("%s\n", device->bind_dev_name);
+		else
+			printf("off\n");
+#else
+		printf("(unsupported)\n");
+#endif
 	} else if (!strcmp(param, "endpoints")) {
 		if (with_interface)
 			printf("%s\t", device->name);

src/showconf.c

@@ -42,6 +42,8 @@ int showconf_main(int argc, const char *argv[])
 		printf("ListenPort = %u\n", device->listen_port);
 	if (device->fwmark)
 		printf("FwMark = 0x%x\n", device->fwmark);
+	if (device->bind_dev)
+		printf("BindDev = %s\n", device->bind_dev_name);
 	if (device->flags & WGDEVICE_HAS_PRIVATE_KEY) {
 		key_to_base64(base64, device->private_key);
 		printf("PrivateKey = %s\n", base64);

src/uapi/linux/linux/wireguard.h

@@ -157,6 +157,7 @@ enum wgdevice_attribute {
 	WGDEVICE_A_LISTEN_PORT,
 	WGDEVICE_A_FWMARK,
 	WGDEVICE_A_PEERS,
+	WGDEVICE_A_BIND_IFINDEX,
 	__WGDEVICE_A_LAST
 };
 #define WGDEVICE_A_MAX (__WGDEVICE_A_LAST - 1)