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