fs/cpuhelper.c

   1 /*
   2  * Copyright (C) 2005 by Latchesar Ionkov <lucho@ionkov.net>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * LATCHESAR IONKOV AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  19  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  20  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include <unistd.h>
  26 #include <sched.h>
  27 #include <string.h>
  28 #include <sys/mount.h>
  29 #include <sys/types.h>
  30 #include <sys/wait.h>
  31 #include <sys/stat.h>
  32 #include <errno.h>
  33 #include <signal.h>
  34 #include <linux/unistd.h>
  35
  36 #define MS_MOVE 8192
  37
  38 static char *host;
  39 static int port;
  40 static char *uname;
  41 static char *cmd;
  42 static char **args;
  43 static char mntpt[256];
  44
  45 int
  46 procfn(void *a)
  47 {
  48         int n;
  49         char opts[256];
  50         char mdir[256];
  51
  52         snprintf(opts, sizeof(opts), "name=%s,port=%d,debug=1", uname, port);
  53         n = mount(host, mntpt, "9P", 0, opts);
  54         if (n < 0) {
  55                 perror("mount");
  56                 return -1;
  57         }
  58
  59         snprintf(mdir, sizeof(mdir), "%s/dev", mntpt);
  60         n = mount("/dev", mdir, NULL, MS_BIND, NULL);
  61         if (n < 0) {
  62                 perror("bind dev");
  63                 return -1;
  64         }
  65
  66         snprintf(mdir, sizeof(mdir), "%s/proc", mntpt);
  67         n = mount("/proc", mdir, NULL, MS_BIND, NULL);
  68         if (n < 0) {
  69                 perror("bind proc");
  70                 return -1;
  71         }
  72
  73         snprintf(mdir, sizeof(mdir), "%s/sys", mntpt);
  74         n = mount("/sys", mdir, NULL, MS_BIND, NULL);
  75         if (n < 0) {
  76                 perror("bind sys");
  77                 return -1;
  78         }
  79
  80         chdir(mntpt);
  81
  82         n = mount(mntpt, "/", NULL, MS_MOVE, NULL);
  83         if (n < 0) {
  84                 perror("move mount");
  85                 return -1;
  86         }
  87
  88         chroot(".");
  89
  90         execv(cmd, args);
  91         snprintf(mdir, sizeof(mdir), "execv %s", cmd);
  92         perror(mdir);
  93         return -1;
  94 }
  95
  96 static void
  97 usage()
  98 {
  99         fprintf(stderr, "cpud uname host port\n");
 100         exit(-1);
 101 }
 102
 103 int
 104 main(int argc, char **argv)
 105 {
 106         int i, nargs;
 107         char *s;
 108         pid_t pid, p;
 109         char stk[10000];
 110
 111         if (argc < 4)
 112                 usage();
 113
 114         uname = argv[1];
 115         host = argv[2];
 116         port = strtol(argv[3], &s, 10);
 117         if (*s != 0)
 118                 usage();
 119
 120         nargs = argc - 3;
 121         if (nargs < 2)
 122                 nargs = 2;
 123
 124         cmd = "/bin/bash";
 125         args = calloc(nargs, sizeof(char *));
 126         if (argc > 4) {
 127                 cmd = argv[4];
 128                 for(i = 4; i < argc; i++)
 129                         args[i-4] = argv[i];
 130         } else {
 131                 cmd = "/bin/bash";
 132                 args[1] = "--login";
 133         }
 134
 135         args[0] = cmd;
 136
 137         snprintf(mntpt, sizeof(mntpt), "/tmp/cpu%d", getpid());
 138         mkdir(mntpt, 0700);
 139         pid = clone(procfn, stk + 5000, CLONE_NEWNS | CLONE_FILES
 140                 | CLONE_PTRACE | SIGCHLD, NULL);
 141
 142         if ((int) pid == -1) {
 143                 perror("clone");
 144                 exit(-1);
 145         }
 146
 147         p = waitpid(pid, NULL, 0);
 148         if ((int) p == -1) {
 149                 perror("waitpid");
 150                 exit(-1);
 151         }
 152
 153         if (!rmdir(mntpt))
 154                 perror("rmdir");
 155
 156         return 0;
 157 }