[PATCH 6/7] tools: allow setting of transit net

[Julian Orth <ju.orth@gmail.com>]

The command is

wg set <device> [...] transit-net <pid|file-path> [...]

For example:

wg set wg0 transit-net 1
wg set wg0 transit-net /proc/1/ns/net
---
 src/tools/config.c     | 32 ++++++++++++++++++++++++++++++++
 src/tools/containers.h |  6 +++++-
 src/tools/ipc.c        |  4 ++++
 src/tools/man/wg.8     |  9 +++++++--
 src/tools/set.c        |  2 +-
 5 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/src/tools/config.c b/src/tools/config.c
index 93525fb..b266026 100644
--- a/src/tools/config.c
+++ b/src/tools/config.c
@@ -14,6 +14,7 @@
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <errno.h>
+#include <fcntl.h>
 
 #include "config.h"
 #include "containers.h"
@@ -74,6 +75,30 @@ static inline bool parse_port(uint16_t *port, uint32_t *flags, const char *value
 	return ret == 0;
 }
 
+static bool parse_transit_net(struct wgdevice *device, const char *arg)
+{
+	/* U32 arg -> PID */
+	if (isdigit(*arg)) {
+		char *end;
+		unsigned long pid = strtoul(arg, &end, 10);
+		if (!*end && pid <= UINT32_MAX) {
+			device->transit_net_pid = pid;
+			device->flags |= WGDEVICE_HAS_TRANSIT_NET_PID;
+			return true;
+		}
+	}
+
+	/* Otherwise -> file path */
+	device->transit_net_fd = open(arg, O_RDONLY);
+	if (device->transit_net_fd >= 0) {
+		device->flags |= WGDEVICE_HAS_TRANSIT_NET_FD;
+		return true;
+	}
+
+	perror("fopen");
+	return false;
+}
+
 static inline bool parse_fwmark(uint32_t *fwmark, uint32_t *flags, const char *value)
 {
 	unsigned long ret;
@@ -392,6 +417,8 @@ static bool process_line(struct config_ctx *ctx, const char *line)
 	if (ctx->is_device_section) {
 		if (key_match("ListenPort"))
 			ret = parse_port(&ctx->device->listen_port, &ctx->device->flags, value);
+		else if (key_match("TransitNet"))
+			ret = parse_transit_net(ctx->device, value);
 		else if (key_match("FwMark"))
 			ret = parse_fwmark(&ctx->device->fwmark, &ctx->device->flags, value);
 		else if (key_match("PrivateKey")) {
@@ -525,6 +552,11 @@ struct wgdevice *config_read_cmd(char *argv[], int argc)
 				goto error;
 			argv += 2;
 			argc -= 2;
+		} else if (!strcmp(argv[0], "transit-net") && argc >= 2 && !peer) {
+			if (!parse_transit_net(device, argv[1]))
+				goto error;
+			argv += 2;
+			argc -= 2;
 		} else if (!strcmp(argv[0], "fwmark") && argc >= 2 && !peer) {
 			if (!parse_fwmark(&device->fwmark, &device->flags, argv[1]))
 				goto error;
diff --git a/src/tools/containers.h b/src/tools/containers.h
index 455d998..188f909 100644
--- a/src/tools/containers.h
+++ b/src/tools/containers.h
@@ -58,7 +58,9 @@ 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_TRANSIT_NET_PID = 1U << 5,
+	WGDEVICE_HAS_TRANSIT_NET_FD = 1U << 6,
 };
 
 struct wgdevice {
@@ -72,6 +74,8 @@ struct wgdevice {
 
 	uint32_t fwmark;
 	uint16_t listen_port;
+	uint32_t transit_net_pid;
+	int transit_net_fd;
 
 	struct wgpeer *first_peer, *last_peer;
 };
diff --git a/src/tools/ipc.c b/src/tools/ipc.c
index e3ef789..1bc98ed 100644
--- a/src/tools/ipc.c
+++ b/src/tools/ipc.c
@@ -569,6 +569,10 @@ again:
 			mnl_attr_put(nlh, WGDEVICE_A_PRIVATE_KEY, sizeof(dev->private_key), dev->private_key);
 		if (dev->flags & WGDEVICE_HAS_LISTEN_PORT)
 			mnl_attr_put_u16(nlh, WGDEVICE_A_LISTEN_PORT, dev->listen_port);
+		if (dev->flags & WGDEVICE_HAS_TRANSIT_NET_PID)
+			mnl_attr_put_u32(nlh, WGDEVICE_A_TRANSIT_NET_PID, dev->transit_net_pid);
+		if (dev->flags & WGDEVICE_HAS_TRANSIT_NET_FD)
+			mnl_attr_put_u32(nlh, WGDEVICE_A_TRANSIT_NET_FD, (uint32_t)dev->transit_net_fd);
 		if (dev->flags & WGDEVICE_HAS_FWMARK)
 			mnl_attr_put_u32(nlh, WGDEVICE_A_FWMARK, dev->fwmark);
 		if (dev->flags & WGDEVICE_REPLACE_PEERS)
diff --git a/src/tools/man/wg.8 b/src/tools/man/wg.8
index 5bae7ca..fd4caab 100644
--- a/src/tools/man/wg.8
+++ b/src/tools/man/wg.8
@@ -55,12 +55,17 @@ 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] [\fItransit-net\fP \fI<pid|file-path>\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
 is not specified, the port will be chosen randomly when the
-interface comes up. Both \fIprivate-key\fP and \fIpreshared-key\fP must
+interface comes up. If transit-net is not specified, the network namespace
+through which encrypted packets are routed is the one in which the device
+was created. Otherwise the network namespace through which encrypted packets are
+routed is the one specified by the argument. If the argument is an unsigned
+32-bit integer, it is interpeted as a process id, otherwise it is interpreted as
+a file path. Both \fIprivate-key\fP and \fIpreshared-key\fP must
 be a files, because command line arguments are not considered private on
 most systems but if you are using
 .BR bash (1),
diff --git a/src/tools/set.c b/src/tools/set.c
index d44fed9..fb11ed0 100644
--- a/src/tools/set.c
+++ b/src/tools/set.c
@@ -18,7 +18,7 @@ int set_main(int argc, 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>] [transit-net <pid|file path>] [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;
 	}
 
-- 
2.18.0