xio-namespaces.c

   1 /* Source: xio-namespaces.c */
   2 /* Copyright Gerhard Rieger and contributors (see file CHANGES) */
   3 /* Published under the GNU General Public License V.2, see file COPYING */
   4
   5 /* This file contains Linux namespace related code */
   6
   7 #include "xiosysincludes.h"
   8 #include "xioopen.h"
   9
  10 #include "xio-namespaces.h"
  11
  12 #if WITH_NAMESPACES
  13
  14 const struct optdesc opt_set_netns   = { "netns",      NULL, OPT_SET_NETNS,   GROUP_PROCESS, PH_INIT, TYPE_STRING, OFUNC_SET_NAMESPACE,   0, 0, 0 };
  15
  16
  17 /* Set the given namespace. Requires root or the appropriate CAP_*-
  18    Returns 0 on success, or -1 on error. */
  19 int xio_set_namespace(
  20         const char *nstype,
  21         const char *nsname)
  22 {
  23         char nspath[PATH_MAX];
  24         int nsfd;
  25         int rc;
  26
  27         if (!xioparms.experimental) {
  28                 Error1("option \"%s\" requires use of --experimental", nstype);
  29         }
  30
  31         snprintf(nspath, sizeof(nspath)-1, "/run/%s/%s", nstype, nsname);
  32         Info1("switching to net namespace \"%s\"", nsname);
  33         nsfd = Open(nspath, O_RDONLY|O_CLOEXEC, 000);
  34         if (nsfd < 0) {
  35                 Error2("open(%s, O_RDONLY|O_CLOEXEC): %s", nspath, strerror(errno));
  36                 return -1;
  37         }
  38         rc = Setns(nsfd, CLONE_NEWNET);
  39         if (rc < 0) {
  40                 Error2("setns(%d, CLONE_NEWNET): %s", nsfd, strerror(errno));
  41                 Close(nsfd);
  42         }
  43         Close(nsfd);
  44         return 0;
  45 }
  46
  47 int xio_apply_namespace(
  48         struct opt *opts)
  49 {
  50         int old_netfd;
  51         char *netns_name;
  52         char old_nspath[PATH_MAX];
  53         int rc;
  54
  55         if (retropt_string(opts, OPT_SET_NETNS, &netns_name) < 0)
  56                 return 0;
  57
  58         /* Get path describing current namespace */
  59         snprintf(old_nspath, sizeof(old_nspath)-1, "/proc/"F_pid"/ns/net",
  60                  Getpid());
  61
  62         /* Get a file descriptor to current ns for later reset */
  63         old_netfd = Open(old_nspath, O_RDONLY|O_CLOEXEC, 000);
  64         if (old_netfd < 0) {
  65                 Error2("open(%s, O_RDONLY|O_CLOEXEC): %s",
  66                        old_nspath, strerror(errno));
  67                 free(netns_name);
  68                 return -1;
  69         }
  70         if (old_netfd == 0) {
  71                 /* 0 means not netns option, oops */
  72                 Error1("%s(): INTERNAL", __func__);
  73                 free(netns_name);
  74                 Close(old_netfd);
  75                 return -1;
  76         }
  77         rc = xio_set_namespace("netns", netns_name);
  78         free(netns_name);
  79         if (rc < 0) {
  80                 Close(old_netfd);
  81                 return -1;
  82         }
  83
  84         return old_netfd;
  85 }
  86
  87 /* Sets the given namespace to that of process 1, this is assumed to be the
  88    systems default.
  89    Returns 0 on success, or -1 on error. */
  90 int xio_reset_namespace(
  91         int saved_netfd)
  92 {
  93         int rc;
  94
  95         rc = Setns(saved_netfd, CLONE_NEWNET);
  96         if (rc < 0) {
  97                 Error2("xio_reset_namespace(%d): %s", saved_netfd, strerror(errno));
  98                 Close(saved_netfd);
  99                 return STAT_NORETRY;
 100         }
 101         Close(saved_netfd);
 102         return 0;
 103 }
 104
 105 #endif /* WITH_NAMESPACES */