1#define _ATFILE_SOURCE
2#include <sys/types.h>
3#include <sys/stat.h>
4#include <sys/wait.h>
5#include <sys/inotify.h>
6#include <sys/mount.h>
7#include <sys/param.h>
8#include <sys/syscall.h>
9#include <stdio.h>
10#include <string.h>
11#include <sched.h>
12#include <fcntl.h>
13#include <dirent.h>
14#include <errno.h>
15#include <unistd.h>
16
17#include "utils.h"
18#include "ip_common.h"
19
20#define NETNS_RUN_DIR "/var/run/netns"
21#define NETNS_ETC_DIR "/etc/netns"
22
23#ifndef CLONE_NEWNET
24#define CLONE_NEWNET 0x40000000	/* New network namespace (lo, device, names sockets, etc) */
25#endif
26
27#ifndef MNT_DETACH
28#define MNT_DETACH	0x00000002	/* Just detach from the tree */
29#endif /* MNT_DETACH */
30
31#ifndef HAVE_SETNS
32static int setns(int fd, int nstype)
33{
34#ifdef __NR_setns
35	return syscall(__NR_setns, fd, nstype);
36#else
37	errno = ENOSYS;
38	return -1;
39#endif
40}
41#endif /* HAVE_SETNS */
42
43
44static void usage(void) __attribute__((noreturn));
45
46static void usage(void)
47{
48	fprintf(stderr, "Usage: ip netns list\n");
49	fprintf(stderr, "       ip netns add NAME\n");
50	fprintf(stderr, "       ip netns delete NAME\n");
51	fprintf(stderr, "       ip netns exec NAME cmd ...\n");
52	fprintf(stderr, "       ip netns monitor\n");
53	exit(-1);
54}
55
56int get_netns_fd(const char *name)
57{
58	char pathbuf[MAXPATHLEN];
59	const char *path, *ptr;
60
61	path = name;
62	ptr = strchr(name, '/');
63	if (!ptr) {
64		snprintf(pathbuf, sizeof(pathbuf), "%s/%s",
65			NETNS_RUN_DIR, name );
66		path = pathbuf;
67	}
68	return open(path, O_RDONLY);
69}
70
71static int netns_list(int argc, char **argv)
72{
73	struct dirent *entry;
74	DIR *dir;
75
76	dir = opendir(NETNS_RUN_DIR);
77	if (!dir)
78		return 0;
79
80	while ((entry = readdir(dir)) != NULL) {
81		if (strcmp(entry->d_name, ".") == 0)
82			continue;
83		if (strcmp(entry->d_name, "..") == 0)
84			continue;
85		printf("%s\n", entry->d_name);
86	}
87	closedir(dir);
88	return 0;
89}
90
91static void bind_etc(const char *name)
92{
93	char etc_netns_path[MAXPATHLEN];
94	char netns_name[MAXPATHLEN];
95	char etc_name[MAXPATHLEN];
96	struct dirent *entry;
97	DIR *dir;
98
99	snprintf(etc_netns_path, sizeof(etc_netns_path), "%s/%s", NETNS_ETC_DIR, name);
100	dir = opendir(etc_netns_path);
101	if (!dir)
102		return;
103
104	while ((entry = readdir(dir)) != NULL) {
105		if (strcmp(entry->d_name, ".") == 0)
106			continue;
107		if (strcmp(entry->d_name, "..") == 0)
108			continue;
109		snprintf(netns_name, sizeof(netns_name), "%s/%s", etc_netns_path, entry->d_name);
110		snprintf(etc_name, sizeof(etc_name), "/etc/%s", entry->d_name);
111		if (mount(netns_name, etc_name, "none", MS_BIND, NULL) < 0) {
112			fprintf(stderr, "Bind %s -> %s failed: %s\n",
113				netns_name, etc_name, strerror(errno));
114		}
115	}
116	closedir(dir);
117}
118
119static int netns_exec(int argc, char **argv)
120{
121	/* Setup the proper environment for apps that are not netns
122	 * aware, and execute a program in that environment.
123	 */
124	const char *name, *cmd;
125	char net_path[MAXPATHLEN];
126	int netns;
127
128	if (argc < 1) {
129		fprintf(stderr, "No netns name specified\n");
130		return -1;
131	}
132	if (argc < 2) {
133		fprintf(stderr, "No cmd specified\n");
134		return -1;
135	}
136	name = argv[0];
137	cmd = argv[1];
138	snprintf(net_path, sizeof(net_path), "%s/%s", NETNS_RUN_DIR, name);
139	netns = open(net_path, O_RDONLY);
140	if (netns < 0) {
141		fprintf(stderr, "Cannot open network namespace: %s\n",
142			strerror(errno));
143		return -1;
144	}
145	if (setns(netns, CLONE_NEWNET) < 0) {
146		fprintf(stderr, "seting the network namespace failed: %s\n",
147			strerror(errno));
148		return -1;
149	}
150
151	if (unshare(CLONE_NEWNS) < 0) {
152		fprintf(stderr, "unshare failed: %s\n", strerror(errno));
153		return -1;
154	}
155	/* Mount a version of /sys that describes the network namespace */
156	if (umount2("/sys", MNT_DETACH) < 0) {
157		fprintf(stderr, "umount of /sys failed: %s\n", strerror(errno));
158		return -1;
159	}
160	if (mount(name, "/sys", "sysfs", 0, NULL) < 0) {
161		fprintf(stderr, "mount of /sys failed: %s\n",strerror(errno));
162		return -1;
163	}
164
165	/* Setup bind mounts for config files in /etc */
166	bind_etc(name);
167
168	if (execvp(cmd, argv + 1)  < 0)
169		fprintf(stderr, "exec of %s failed: %s\n",
170			cmd, strerror(errno));
171	exit(-1);
172}
173
174static int netns_delete(int argc, char **argv)
175{
176	const char *name;
177	char netns_path[MAXPATHLEN];
178
179	if (argc < 1) {
180		fprintf(stderr, "No netns name specified\n");
181		return -1;
182	}
183
184	name = argv[0];
185	snprintf(netns_path, sizeof(netns_path), "%s/%s", NETNS_RUN_DIR, name);
186	umount2(netns_path, MNT_DETACH);
187	if (unlink(netns_path) < 0) {
188		fprintf(stderr, "Cannot remove %s: %s\n",
189			netns_path, strerror(errno));
190		return -1;
191	}
192	return 0;
193}
194
195static int netns_add(int argc, char **argv)
196{
197	/* This function creates a new network namespace and
198	 * a new mount namespace and bind them into a well known
199	 * location in the filesystem based on the name provided.
200	 *
201	 * The mount namespace is created so that any necessary
202	 * userspace tweaks like remounting /sys, or bind mounting
203	 * a new /etc/resolv.conf can be shared between uers.
204	 */
205	char netns_path[MAXPATHLEN];
206	const char *name;
207	int fd;
208
209	if (argc < 1) {
210		fprintf(stderr, "No netns name specified\n");
211		return -1;
212	}
213	name = argv[0];
214
215	snprintf(netns_path, sizeof(netns_path), "%s/%s", NETNS_RUN_DIR, name);
216
217	/* Create the base netns directory if it doesn't exist */
218	mkdir(NETNS_RUN_DIR, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
219
220	/* Create the filesystem state */
221	fd = open(netns_path, O_RDONLY|O_CREAT|O_EXCL, 0);
222	if (fd < 0) {
223		fprintf(stderr, "Could not create %s: %s\n",
224			netns_path, strerror(errno));
225		return -1;
226	}
227	close(fd);
228	if (unshare(CLONE_NEWNET) < 0) {
229		fprintf(stderr, "Failed to create a new network namespace: %s\n",
230			strerror(errno));
231		goto out_delete;
232	}
233
234	/* Bind the netns last so I can watch for it */
235	if (mount("/proc/self/ns/net", netns_path, "none", MS_BIND, NULL) < 0) {
236		fprintf(stderr, "Bind /proc/self/ns/net -> %s failed: %s\n",
237			netns_path, strerror(errno));
238		goto out_delete;
239	}
240	return 0;
241out_delete:
242	netns_delete(argc, argv);
243	exit(-1);
244	return -1;
245}
246
247
248static int netns_monitor(int argc, char **argv)
249{
250	char buf[4096];
251	struct inotify_event *event;
252	int fd;
253	fd = inotify_init();
254	if (fd < 0) {
255		fprintf(stderr, "inotify_init failed: %s\n",
256			strerror(errno));
257		return -1;
258	}
259	if (inotify_add_watch(fd, NETNS_RUN_DIR, IN_CREATE | IN_DELETE) < 0) {
260		fprintf(stderr, "inotify_add_watch failed: %s\n",
261			strerror(errno));
262		return -1;
263	}
264	for(;;) {
265		ssize_t len = read(fd, buf, sizeof(buf));
266		if (len < 0) {
267			fprintf(stderr, "read failed: %s\n",
268				strerror(errno));
269			return -1;
270		}
271		for (event = (struct inotify_event *)buf;
272		     (char *)event < &buf[len];
273		     event = (struct inotify_event *)((char *)event + sizeof(*event) + event->len)) {
274			if (event->mask & IN_CREATE)
275				printf("add %s\n", event->name);
276			if (event->mask & IN_DELETE)
277				printf("delete %s\n", event->name);
278		}
279	}
280	return 0;
281}
282
283int do_netns(int argc, char **argv)
284{
285	if (argc < 1)
286		return netns_list(0, NULL);
287
288	if ((matches(*argv, "list") == 0) || (matches(*argv, "show") == 0) ||
289	    (matches(*argv, "lst") == 0))
290		return netns_list(argc-1, argv+1);
291
292	if (matches(*argv, "help") == 0)
293		usage();
294
295	if (matches(*argv, "add") == 0)
296		return netns_add(argc-1, argv+1);
297
298	if (matches(*argv, "delete") == 0)
299		return netns_delete(argc-1, argv+1);
300
301	if (matches(*argv, "exec") == 0)
302		return netns_exec(argc-1, argv+1);
303
304	if (matches(*argv, "monitor") == 0)
305		return netns_monitor(argc-1, argv+1);
306
307	fprintf(stderr, "Command \"%s\" is unknown, try \"ip netns help\".\n", *argv);
308	exit(-1);
309}
310