mount-setup.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/mount.h>
  23 #include <errno.h>
  24 #include <sys/stat.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <libgen.h>
  28 #include <assert.h>
  29
  30 #include "mount-setup.h"
  31 #include "log.h"
  32 #include "macro.h"
  33 #include "util.h"
  34
  35 typedef struct MountPoint {
  36         const char *what;
  37         const char *where;
  38         const char *type;
  39         const char *options;
  40         unsigned long flags;
  41         bool fatal;
  42 } MountPoint;
  43
  44 static const MountPoint mount_table[] = {
  45         { "proc",        "/proc",                    "proc",        NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
  46         { "sysfs",       "/sys",                     "sysfs",       NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
  47         { "devtmps",     "/dev",                     "devtmpfs",    "mode=755",  MS_NOSUID,                    true },
  48         { "tmpfs",       "/dev/shm",                 "tmpfs",       "mode=1777", MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
  49         { "devpts",      "/dev/pts",                 "devpts",      NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
  50         { "cgroup",      "/cgroup/debug",            "cgroup",      "debug",     MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
  51         { "debugfs",     "/sys/kernel/debug",        "debugfs",     NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
  52         { "binfmt_misc", "/proc/sys/fs/binfmt_misc", "binfmt_misc", NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
  53 };
  54
  55 bool mount_point_is_api(const char *path) {
  56         unsigned i;
  57
  58         /* Checks if this mount point is considered "API", and hence
  59          * should be ignored */
  60
  61         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
  62                 if (path_startswith(path, mount_table[i].where))
  63                         return true;
  64
  65         return path_startswith(path, "/cgroup/");
  66 }
  67
  68 static int mount_one(const MountPoint *p) {
  69         int r;
  70
  71         assert(p);
  72
  73         if ((r = path_is_mount_point(p->where)) < 0)
  74                 return r;
  75
  76         if (r > 0)
  77                 return 0;
  78
  79         /* The access mode here doesn't really matter too much, since
  80          * the mounted file system will take precedence anyway. */
  81         mkdir_p(p->where, 0755);
  82
  83         log_debug("Mounting %s to %s of type %s with options %s.",
  84                   p->what,
  85                   p->where,
  86                   p->type,
  87                   strna(p->options));
  88
  89         if (mount(p->what,
  90                   p->where,
  91                   p->type,
  92                   p->flags,
  93                   p->options) < 0) {
  94                 log_error("Failed to mount %s: %s", p->where, strerror(errno));
  95                 return p->fatal ? -errno : 0;
  96         }
  97
  98         return 0;
  99 }
 100
 101 static int mount_cgroup_controllers(void) {
 102         int r;
 103         FILE *f;
 104         char buf [256];
 105
 106         /* Mount all available cgroup controllers. */
 107
 108         if (!(f = fopen("/proc/cgroups", "re")))
 109                 return -ENOENT;
 110
 111         /* Ignore the header line */
 112         fgets(buf, sizeof(buf), f);
 113
 114         for (;;) {
 115                 MountPoint p;
 116                 char *controller, *where;
 117
 118                 if (fscanf(f, "%ms %*i %*i %*i", &controller) != 1) {
 119
 120                         if (feof(f))
 121                                 break;
 122
 123                         log_error("Failed to parse /proc/cgroups.");
 124                         r = -EIO;
 125                         goto finish;
 126                 }
 127
 128                 if (asprintf(&where, "/cgroup/%s", controller) < 0) {
 129                         free(controller);
 130                         r = -ENOMEM;
 131                         goto finish;
 132                 }
 133
 134                 zero(p);
 135                 p.what = "cgroup";
 136                 p.where = where;
 137                 p.type = "cgroup";
 138                 p.options = controller;
 139                 p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
 140                 p.fatal = false;
 141
 142                 r = mount_one(&p);
 143                 free(controller);
 144                 free(where);
 145
 146                 if (r < 0)
 147                         goto finish;
 148         }
 149
 150         r = 0;
 151
 152 finish:
 153         fclose(f);
 154
 155         return r;
 156 }
 157
 158 int mount_setup(void) {
 159         int r;
 160         unsigned i;
 161
 162         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
 163                 if ((r = mount_one(mount_table+i)) < 0)
 164                         return r;
 165
 166         return mount_cgroup_controllers();
 167 }