socket: enable setting of fwmark

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

src/completion/wg.bash-completion

@@ -19,7 +19,7 @@ _wg_completion() {
 	fi
 
 	if [[ $COMP_CWORD -eq 3 && ${COMP_WORDS[1]} == show && ${COMP_WORDS[2]} != interfaces ]]; then
-		COMPREPLY+=( $(compgen -W "public-key private-key preshared-key listen-port peers endpoints allowed-ips latest-handshakes persistent-keepalive transfer" -- "${COMP_WORDS[3]}") )
+		COMPREPLY+=( $(compgen -W "public-key private-key preshared-key listen-port peers endpoints allowed-ips fwmark latest-handshakes persistent-keepalive transfer" -- "${COMP_WORDS[3]}") )
 		return
 	fi
 
@@ -31,9 +31,10 @@ _wg_completion() {
 
 	[[ ${COMP_WORDS[1]} == set ]] || return
 
-	local has_listen_port=0 has_private_key=0 has_preshared_key=0 has_peer=0 has_remove=0 has_endpoint=0 has_persistent_keepalive=0 has_allowed_ips=0 words=() i j
+	local has_listen_port=0 has_fwmark=0 has_private_key=0 has_preshared_key=0 has_peer=0 has_remove=0 has_endpoint=0 has_persistent_keepalive=0 has_allowed_ips=0 words=() i j
 	for ((i=3;i<COMP_CWORD;i+=2)); do
 		[[ ${COMP_WORDS[i]} == listen-port ]] && has_listen_port=1
+		[[ ${COMP_WORDS[i]} == fwmark ]] && has_fwmark=1
 		[[ ${COMP_WORDS[i]} == private-key ]] && has_private_key=1
 		[[ ${COMP_WORDS[i]} == preshared-key ]] && has_preshared_key=1
 		[[ ${COMP_WORDS[i]} == peer ]] && { has_peer=$i; break; }
@@ -41,6 +42,7 @@ _wg_completion() {
 	if [[ $has_peer -eq 0 ]]; then
 		if ((COMP_CWORD % 2 != 0)); then
 			[[ $has_listen_port -eq 1 ]] || words+=( listen-port )
+			[[ $has_fwmark -eq 1 ]] || words+=( fwmark )
 			[[ $has_private_key -eq 1 ]] || words+=( private-key )
 			[[ $has_preshared_key -eq 1 ]] || words+=( preshared-key )
 			words+=( peer )

src/config.c

@@ -91,6 +91,25 @@ static inline uint16_t parse_port(const char *value)
 	return port;
 }
 
+static inline bool parse_fwmark(uint32_t *fwmark, unsigned int *flags, const char *value)
+{
+	unsigned long ret;
+	char *end;
+	int base = 10;
+
+	if (value[0] == '0' && value[1] == 'x') {
+		value += 2;
+		base = 16;
+	}
+	ret = strtoul(value, &end, base);
+	if (!*value || *end || ret > UINT32_MAX)
+		return false;
+	*fwmark = ret;
+	if (!ret)
+		*flags |= WGDEVICE_REMOVE_FWMARK;
+	return true;
+}
+
 static inline bool parse_key(uint8_t key[static WG_KEY_LEN], const char *value)
 {
 	uint8_t tmp[WG_KEY_LEN + 1];
@@ -281,6 +300,8 @@ static bool process_line(struct config_ctx *ctx, const char *line)
 	if (ctx->is_device_section) {
 		if (key_match("ListenPort"))
 			ret = !!(ctx->buf.dev->port = parse_port(value));
+		else if (key_match("FwMark"))
+			ret = parse_fwmark(&ctx->buf.dev->fwmark, &ctx->buf.dev->flags, value);
 		else if (key_match("PrivateKey")) {
 			ret = parse_key(ctx->buf.dev->private_key, value);
 			if (!ret)
@@ -372,6 +393,8 @@ bool config_read_finish(struct config_ctx *ctx)
 	}
 	if (ctx->buf.dev->flags & WGDEVICE_REPLACE_PEERS && !key_is_valid(ctx->buf.dev->preshared_key))
 		ctx->buf.dev->flags |= WGDEVICE_REMOVE_PRESHARED_KEY;
+	if (ctx->buf.dev->flags & WGDEVICE_REPLACE_PEERS && !ctx->buf.dev->fwmark)
+		ctx->buf.dev->flags |= WGDEVICE_REMOVE_FWMARK;
 
 	for_each_wgpeer(ctx->buf.dev, peer, i) {
 		if (!key_is_valid(peer->public_key)) {
@@ -448,6 +471,11 @@ bool config_read_cmd(struct wgdevice **device, char *argv[], int argc)
 				goto error;
 			argv += 2;
 			argc -= 2;
+		} else if (!strcmp(argv[0], "fwmark") && argc >= 2 && !buf.dev->num_peers) {
+			if (!parse_fwmark(&buf.dev->fwmark, &buf.dev->flags, argv[1]))
+				goto error;
+			argv += 2;
+			argc -= 2;
 		} else if (!strcmp(argv[0], "private-key") && argc >= 2 && !buf.dev->num_peers) {
 			char *line;
 			int ret = read_line(&line, argv[1]);

src/set.c

@@ -13,7 +13,7 @@ int set_main(int argc, char *argv[])
 	int ret = 1;
 
 	if (argc < 3) {
-		fprintf(stderr, "Usage: %s %s <interface> [listen-port <port>] [private-key <file path>] [peer <base64 public key> [remove] [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>] [fwmark <mark>] [private-key <file path>] [peer <base64 public key> [remove] [endpoint <ip>:<port>] [persistent-keepalive <interval seconds>] [allowed-ips <ip1>/<cidr1>[,<ip2>/<cidr2>]...] ]...\n", PROG_NAME, argv[0]);
 		return 1;
 	}
 

src/show.c

@@ -203,7 +203,7 @@ static char *bytes(uint64_t b)
 static const char *COMMAND_NAME = NULL;
 static void show_usage(void)
 {
-	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | preshared-key | listen-port | peers | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive]\n", PROG_NAME, COMMAND_NAME);
+	fprintf(stderr, "Usage: %s %s { <interface> | all | interfaces } [public-key | private-key | preshared-key | listen-port | fwmark | peers | endpoints | allowed-ips | latest-handshakes | transfer | persistent-keepalive]\n", PROG_NAME, COMMAND_NAME);
 }
 
 static void pretty_print(struct wgdevice *device)
@@ -222,6 +222,8 @@ static void pretty_print(struct wgdevice *device)
 		terminal_printf("  " TERMINAL_BOLD "pre-shared key" TERMINAL_RESET ": %s\n", masked_key(device->preshared_key));
 	if (device->port)
 		terminal_printf("  " TERMINAL_BOLD "listening port" TERMINAL_RESET ": %u\n", device->port);
+	if (device->fwmark)
+		terminal_printf("  " TERMINAL_BOLD "fwmark" TERMINAL_RESET ": 0x%x\n", device->fwmark);
 	if (device->num_peers) {
 		sort_peers(device);
 		terminal_printf("\n");
@@ -271,6 +273,10 @@ static bool ugly_print(struct wgdevice *device, const char *param, bool with_int
 		if (with_interface)
 			printf("%s\t", device->interface);
 		printf("%u\n", device->port);
+	} else if (!strcmp(param, "fwmark")) {
+		if (with_interface)
+			printf("%s\t", device->interface);
+		printf("0x%x\n", device->fwmark);
 	} else if (!strcmp(param, "endpoints")) {
 		if (with_interface)
 			printf("%s\t", device->interface);

src/showconf.c

@@ -44,7 +44,9 @@ int showconf_main(int argc, char *argv[])
 
 	printf("[Interface]\n");
 	if (device->port)
-		printf("ListenPort = %d\n", device->port);
+		printf("ListenPort = %u\n", device->port);
+	if (device->fwmark)
+		printf("FwMark = 0x%x\n", device->fwmark);
 	if (memcmp(device->private_key, zero, WG_KEY_LEN)) {
 		b64_ntop(device->private_key, WG_KEY_LEN, b64, b64_len(WG_KEY_LEN));
 		printf("PrivateKey = %s\n", b64);

src/wg-quick.bash

@@ -78,10 +78,15 @@ add_if() {
 }
 
 del_if() {
-	if [[ $(ip route show table all) =~ .*\ dev\ $INTERFACE\ table\ ([0-9]+)\ .* ]]; then
+	DEFAULT_TABLE=$(("$(wg show "$INTERFACE" fwmark)"))
-		while [[ -n $(ip rule show table ${BASH_REMATCH[1]}) ]]; do
+	if [[ $DEFAULT_TABLE -ne 0 ]]; then
-			cmd ip rule delete table "${BASH_REMATCH[1]}"
+		while [[ -n $(ip -4 rule show table $DEFAULT_TABLE) ]]; do
-			[[ $(ip rule show table main) == *"from all lookup main suppress_prefixlength 0"* ]] && cmd ip rule delete table main suppress_prefixlength 0
+			cmd ip -4 rule delete table $DEFAULT_TABLE
+			[[ $(ip -4 rule show table main) == *"from all lookup main suppress_prefixlength 0"* ]] && cmd ip -4 rule delete table main suppress_prefixlength 0
+		done
+		while [[ -n $(ip -6 rule show table $DEFAULT_TABLE) ]]; do
+			cmd ip -6 rule delete table $DEFAULT_TABLE
+			[[ $(ip -6 rule show table main) == *"from all lookup main suppress_prefixlength 0"* ]] && cmd ip -6 rule delete table main suppress_prefixlength 0
 		done
 	fi
 	cmd ip link delete dev "$INTERFACE"
@@ -104,22 +109,22 @@ add_route() {
 }
 
 DEFAULT_TABLE=
-PREVIOUS_ENDPOINT=
 add_default() {
-	[[ $(join <(wg show "$INTERFACE" allowed-ips) <(wg show "$INTERFACE" endpoints)) =~ ([A-Za-z0-9/+=]{44})\ ([0-9a-f/.:]+ )*${1//./\\.}\ ([0-9a-f/.:]+ )*\[?([0-9.:a-f]+)\]?:[0-9]+ ]] && local endpoint="${BASH_REMATCH[4]}"
-	[[ -n $endpoint ]] || return 0
-	local first=0
 	if [[ -z $DEFAULT_TABLE ]]; then
-		first=1
 		DEFAULT_TABLE=51820
 		while [[ -n $(ip route show table $DEFAULT_TABLE) ]]; do ((DEFAULT_TABLE++)); done
 	fi
-	cmd ip route add "$1" dev "$INTERFACE" table $DEFAULT_TABLE
+	local proto=-4
-	[[ $PREVIOUS_ENDPOINT == "$endpoint" ]] && return 0
+	[[ $1 == *:* ]] && proto=-6
-	PREVIOUS_ENDPOINT="$endpoint"
+	cmd wg set "$INTERFACE" fwmark $DEFAULT_TABLE
-	cmd ip rule add not to "$endpoint" table $DEFAULT_TABLE
+	cmd ip $proto route add "$1" dev "$INTERFACE" table $DEFAULT_TABLE
-	[[ $first -eq 1 ]] || return 0
+	cmd ip $proto rule add not fwmark $DEFAULT_TABLE table $DEFAULT_TABLE
-	cmd ip rule add table main suppress_prefixlength 0
+	cmd ip $proto rule add table main suppress_prefixlength 0
+	local key equals value
+	while read -r key equals value; do
+		[[ $value -eq 1 ]] && sysctl -q "$key=2"
+	done < <(sysctl -a -r 'net\.ipv4.conf\..+\.rp_filter')
+	return 0
 }
 
 set_config() {

src/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 | \fIpreshared-key\fP | \fIlisten-port\fP | \fIpeers\fP | \fIendpoints\fP | \fIallowed-ips\fP | \fIlatest-handshakes\fP | \fIpersistent-keepalive\fP | \fItransfer\fP]
+\fBshow\fP { \fI<interface>\fP | \fIall\fP | \fIinterfaces\fP } [\fIpublic-key\fP | \fIprivate-key\fP | \fIpreshared-key\fP | \fIlisten-port\fP | \fIfwmark\fP | \fIpeers\fP | \fIendpoints\fP | \fIallowed-ips\fP | \fIlatest-handshakes\fP | \fIpersistent-keepalive\fP | \fItransfer\fP]
 Shows current WireGuard configuration 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,
@@ -49,7 +49,7 @@ newlines and tabs, meant to be used in scripts.
 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] [\fIprivate-key\fP \fI<file-path>\fP] [\fIpreshared-key\fP \fI<file-path>\fP] [\fIpeer\fP \fI<base64-public-key>\fP [\fIremove\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] [\fIfwmark\fP \fI<fwmark>\fP] [\fIprivate-key\fP \fI<file-path>\fP] [\fIpreshared-key\fP \fI<file-path>\fP] [\fIpeer\fP \fI<base64-public-key>\fP [\fIremove\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
@@ -125,6 +125,8 @@ for post-quantum resistance.
 .IP \(bu
 ListenPort \(em a 16-bit port for listening. Optional; if not specified, chosen
 randomly.
+.IP \(bu
+FwMark \(em a 32-bit fwmark for outgoing packets. Optional.
 .P
 The \fIPeer\fP sections may contain the following fields:
 .IP \(bu