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 };
  53
  54 bool mount_point_is_api(const char *path) {
  55         unsigned i;
  56
  57         /* Checks if this mount point is considered "API", and hence
  58          * should be ignored */
  59
  60         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
  61                 if (path_startswith(path, mount_table[i].where))
  62                         return true;
  63
  64         return false;
  65 }
  66
  67 static int mount_one(const MountPoint *p) {
  68         int r;
  69
  70         assert(p);
  71
  72         if ((r = path_is_mount_point(p->where)) < 0)
  73                 return r;
  74
  75         if (r > 0)
  76                 return 0;
  77
  78         /* The access mode here doesn't really matter too much, since
  79          * the mounted file system will take precedence anyway. */
  80         mkdir_p(p->where, 0755);
  81
  82         log_debug("Mounting %s to %s of type %s with options %s.",
  83                   p->what,
  84                   p->where,
  85                   p->type,
  86                   strna(p->options));
  87
  88         if (mount(p->what,
  89                   p->where,
  90                   p->type,
  91                   p->flags,
  92                   p->options) < 0) {
  93                 log_error("Failed to mount %s: %s", p->where, strerror(errno));
  94                 return p->fatal ? -errno : 0;
  95         }
  96
  97         return 0;
  98 }
  99
 100 static int mount_cgroup_controllers(void) {
 101         int r;
 102         FILE *f;
 103         char buf [256];
 104
 105         /* Mount all available cgroup controllers. */
 106
 107         if (!(f = fopen("/proc/cgroups", "re")))
 108                 return -ENOENT;
 109
 110         /* Ignore the header line */
 111         fgets(buf, sizeof(buf), f);
 112
 113         for (;;) {
 114                 MountPoint p;
 115                 char *controller, *where;
 116
 117                 if (fscanf(f, "%ms %*i %*i %*i", &controller) != 1) {
 118
 119                         if (feof(f))
 120                                 break;
 121
 122                         log_error("Failed to parse /proc/cgroups.");
 123                         r = -EIO;
 124                         goto finish;
 125                 }
 126
 127                 if (asprintf(&where, "/cgroup/%s", controller) < 0) {
 128                         free(controller);
 129                         r = -ENOMEM;
 130                         goto finish;
 131                 }
 132
 133                 zero(p);
 134                 p.what = "cgroup";
 135                 p.where = where;
 136                 p.type = "cgroup";
 137                 p.options = controller;
 138                 p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
 139                 p.fatal = false;
 140
 141                 r = mount_one(&p);
 142                 free(controller);
 143                 free(where);
 144
 145                 if (r < 0)
 146                         goto finish;
 147         }
 148
 149         r = 0;
 150
 151 finish:
 152         fclose(f);
 153
 154         return r;
 155 }
 156
 157 int mount_setup(void) {
 158         int r;
 159         unsigned i;
 160
 161         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
 162                 if ((r = mount_one(mount_table+i)) < 0)
 163                         return r;
 164
 165         return mount_cgroup_controllers();
 166 }