Add the more simple utility to unshare the namespaces.

From: Daniel Lezcano <dlezcano@fr.ibm.com>

lt-lxc-unshare <options> [command]
Options are:
	 -f      : fork and unshare (automatic when unsharing the pids)
	 -m      : unshare the mount points
	 -p      : unshare the pids
	 -h      : unshare the utsname
	 -i      : unshare the sysv ipc
	 -n      : unshare the network
	 -u <id> : unshare the users and set a new id
	 if -f or -p is specified, <command> is mandatory)

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

diff --git a/src/lxc/lxc_unshare.c b/src/lxc/lxc_unshare.c
new file mode 100644 (file)
index 0000000..489ede0
--- /dev/null
+++ b/src/lxc/lxc_unshare.c
@@ -0,0 +1,147 @@
+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <dlezcano at fr.ibm.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <getopt.h>
+#include <string.h>
+#include <signal.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "lxc_namespace.h"
+
+void usage(char *cmd)
+{
+       fprintf(stderr, "%s <options> [command]\n", basename(cmd));
+       fprintf(stderr, "Options are:\n");
+       fprintf(stderr, "\t -f      : fork and unshare (automatic when unsharing the pids)\n");
+       fprintf(stderr, "\t -m      : unshare the mount points\n");
+       fprintf(stderr, "\t -p      : unshare the pids\n");
+       fprintf(stderr, "\t -h      : unshare the utsname\n");
+       fprintf(stderr, "\t -i      : unshare the sysv ipc\n");
+       fprintf(stderr, "\t -n      : unshare the network\n");
+       fprintf(stderr, "\t -u <id> : unshare the users and set a new id\n");
+       fprintf(stderr, "\t if -f or -p is specified, <command> is mandatory)\n");
+       _exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+       int nbargs = 0, status = 1, hastofork = 0;
+       char **args, opt;
+       long flags = 0;
+       uid_t uid;
+       pid_t pid;
+
+       while ((opt = getopt(argc, argv, "fmphiu:n")) != -1) {
+               switch (opt) {
+               case 'm':
+                       flags |= CLONE_NEWNS;
+                       break;
+               case 'p':
+                       flags |= CLONE_NEWPID;
+                       break;
+               case 'h':
+                       flags |= CLONE_NEWUTS;
+                       break;
+               case 'i':
+                       flags |= CLONE_NEWIPC;
+                       break;
+               case 'u':
+                       flags |= CLONE_NEWUSER;
+                       uid = atoi(optarg);
+                       break;
+               case 'n':
+                       flags |= CLONE_NEWNET;
+                       break;
+               case 'f':
+                       hastofork = 1;
+                       break;
+               }
+
+               nbargs++;
+       }
+
+       args = &argv[optind];
+       argc -= nbargs;
+
+       if (!flags)
+               usage(argv[0]);
+
+       if ((flags & CLONE_NEWPID) || hastofork) {
+
+               if (!argv[optind] || !strlen(argv[optind]))
+                       usage(argv[0]);
+
+               pid = fork_ns(flags);
+
+               if (pid < 0) {
+                       fprintf(stderr, "failed to fork into a new namespace: %s\n",
+                               strerror(errno));
+                       return 1;
+               }
+
+               if (!pid) {
+                       if (flags & CLONE_NEWUSER && setuid(uid)) {
+                               fprintf(stderr, "failed to set uid %d: %s\n",
+                                       uid, strerror(errno));
+                               exit(1);
+                       }
+
+                       execvp(args[0], args);
+                       fprintf(stderr, "failed to exec: '%s': %s\n",
+                               argv[0], strerror(errno));
+                       exit(1);
+               }
+               
+               if (waitpid(pid, &status, 0) < 0)
+                       fprintf(stderr, "failed to wait for '%d'\n", pid);
+               
+               return status;
+       }
+
+       if (unshare_ns(flags)) {
+               fprintf(stderr, "failed to unshare the current process: %s\n",
+                       strerror(errno));
+               return 1;
+       }
+
+       if (flags & CLONE_NEWUSER && setuid(uid)) {
+               fprintf(stderr, "failed to set uid %d: %s\n",
+                       uid, strerror(errno));
+               return 1;
+       }
+
+       if (argv[optind] && strlen(argv[optind])) {
+               execvp(args[0], args);
+               fprintf(stderr, "failed to exec: '%s': %s\n",
+                       argv[0], strerror(errno));
+               return 1;
+       }
+
+       return 0;
+}
+