lib/namespace.c

   1 /*
   2  * namespace.c
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <fcntl.h>
  11 #include <dirent.h>
  12 #include <limits.h>
  13
  14 #include "utils.h"
  15 #include "namespace.h"
  16
  17 static void bind_etc(const char *name)
  18 {
  19         char etc_netns_path[PATH_MAX];
  20         char netns_name[PATH_MAX];
  21         char etc_name[PATH_MAX];
  22         struct dirent *entry;
  23         DIR *dir;
  24
  25         snprintf(etc_netns_path, sizeof(etc_netns_path), "%s/%s", NETNS_ETC_DIR, name);
  26         dir = opendir(etc_netns_path);
  27         if (!dir)
  28                 return;
  29
  30         while ((entry = readdir(dir)) != NULL) {
  31                 if (strcmp(entry->d_name, ".") == 0)
  32                         continue;
  33                 if (strcmp(entry->d_name, "..") == 0)
  34                         continue;
  35                 snprintf(netns_name, sizeof(netns_name), "%s/%s", etc_netns_path, entry->d_name);
  36                 snprintf(etc_name, sizeof(etc_name), "/etc/%s", entry->d_name);
  37                 if (mount(netns_name, etc_name, "none", MS_BIND, NULL) < 0) {
  38                         fprintf(stderr, "Bind %s -> %s failed: %s\n",
  39                                 netns_name, etc_name, strerror(errno));
  40                 }
  41         }
  42         closedir(dir);
  43 }
  44
  45 int netns_switch(char *name)
  46 {
  47         char net_path[PATH_MAX];
  48         int netns;
  49
  50         snprintf(net_path, sizeof(net_path), "%s/%s", NETNS_RUN_DIR, name);
  51         netns = open(net_path, O_RDONLY | O_CLOEXEC);
  52         if (netns < 0) {
  53                 fprintf(stderr, "Cannot open network namespace \"%s\": %s\n",
  54                         name, strerror(errno));
  55                 return -1;
  56         }
  57
  58         if (setns(netns, CLONE_NEWNET) < 0) {
  59                 fprintf(stderr, "setting the network namespace \"%s\" failed: %s\n",
  60                         name, strerror(errno));
  61                 goto fail_close;
  62         }
  63
  64         if (unshare(CLONE_NEWNS) < 0) {
  65                 fprintf(stderr, "unshare failed: %s\n", strerror(errno));
  66                 goto fail_close;
  67         }
  68         /* Don't let any mounts propagate back to the parent */
  69         if (mount("", "/", "none", MS_SLAVE | MS_REC, NULL)) {
  70                 fprintf(stderr, "\"mount --make-rslave /\" failed: %s\n",
  71                         strerror(errno));
  72                 goto fail_close;
  73         }
  74         /* Mount a version of /sys that describes the network namespace */
  75         if (umount2("/sys", MNT_DETACH) < 0) {
  76                 fprintf(stderr, "umount of /sys failed: %s\n", strerror(errno));
  77                 goto fail_close;
  78         }
  79         if (mount(name, "/sys", "sysfs", 0, NULL) < 0) {
  80                 fprintf(stderr, "mount of /sys failed: %s\n",strerror(errno));
  81                 goto fail_close;
  82         }
  83
  84         /* Setup bind mounts for config files in /etc */
  85         bind_etc(name);
  86         return 0;
  87 fail_close:
  88         close(netns);
  89         return -1;
  90 }
  91
  92 int netns_get_fd(const char *name)
  93 {
  94         char pathbuf[PATH_MAX];
  95         const char *path, *ptr;
  96
  97         path = name;
  98         ptr = strchr(name, '/');
  99         if (!ptr) {
 100                 snprintf(pathbuf, sizeof(pathbuf), "%s/%s",
 101                         NETNS_RUN_DIR, name );
 102                 path = pathbuf;
 103         }
 104         return open(path, O_RDONLY);
 105 }
 106
 107 int netns_foreach(int (*func)(char *nsname, void *arg), void *arg)
 108 {
 109         DIR *dir;
 110         struct dirent *entry;
 111
 112         dir = opendir(NETNS_RUN_DIR);
 113         if (!dir)
 114                 return -1;
 115
 116         while ((entry = readdir(dir)) != NULL) {
 117                 if (strcmp(entry->d_name, ".") == 0)
 118                         continue;
 119                 if (strcmp(entry->d_name, "..") == 0)
 120                         continue;
 121                 if (func(entry->d_name, arg))
 122                         break;
 123         }
 124
 125         closedir(dir);
 126         return 0;
 127 }