src/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/systemd",          "cgroup",      "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
  51 };
  52
  53 bool mount_point_is_api(const char *path) {
  54         unsigned i;
  55
  56         /* Checks if this mount point is considered "API", and hence
  57          * should be ignored */
  58
  59         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
  60                 if (path_startswith(path, mount_table[i].where))
  61                         return true;
  62
  63         return path_startswith(path, "/cgroup/");
  64 }
  65
  66 static int mount_one(const MountPoint *p) {
  67         int r;
  68
  69         assert(p);
  70
  71         if ((r = path_is_mount_point(p->where)) < 0)
  72                 return r;
  73
  74         if (r > 0)
  75                 return 0;
  76
  77         /* The access mode here doesn't really matter too much, since
  78          * the mounted file system will take precedence anyway. */
  79         mkdir_p(p->where, 0755);
  80
  81         log_debug("Mounting %s to %s of type %s with options %s.",
  82                   p->what,
  83                   p->where,
  84                   p->type,
  85                   strna(p->options));
  86
  87         if (mount(p->what,
  88                   p->where,
  89                   p->type,
  90                   p->flags,
  91                   p->options) < 0) {
  92                 log_error("Failed to mount %s: %s", p->where, strerror(errno));
  93                 return p->fatal ? -errno : 0;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int mount_cgroup_controllers(void) {
 100         int r;
 101         FILE *f;
 102         char buf [256];
 103
 104         /* Mount all available cgroup controllers that are built into the kernel. */
 105
 106         if (!(f = fopen("/proc/cgroups", "re")))
 107                 return -ENOENT;
 108
 109         /* Ignore the header line */
 110         (void) fgets(buf, sizeof(buf), f);
 111
 112         for (;;) {
 113                 MountPoint p;
 114                 char *controller, *where;
 115
 116                 if (fscanf(f, "%ms %*i %*i %*i", &controller) != 1) {
 117
 118                         if (feof(f))
 119                                 break;
 120
 121                         log_error("Failed to parse /proc/cgroups.");
 122                         r = -EIO;
 123                         goto finish;
 124                 }
 125
 126                 if (asprintf(&where, "/cgroup/%s", controller) < 0) {
 127                         free(controller);
 128                         r = -ENOMEM;
 129                         goto finish;
 130                 }
 131
 132                 zero(p);
 133                 p.what = "cgroup";
 134                 p.where = where;
 135                 p.type = "cgroup";
 136                 p.options = controller;
 137                 p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
 138                 p.fatal = false;
 139
 140                 r = mount_one(&p);
 141                 free(controller);
 142                 free(where);
 143
 144                 if (r < 0)
 145                         goto finish;
 146         }
 147
 148         r = 0;
 149
 150 finish:
 151         fclose(f);
 152
 153         return r;
 154 }
 155
 156 int mount_setup(void) {
 157         int r;
 158         unsigned i;
 159
 160         for (i = 0; i < ELEMENTSOF(mount_table); i ++)
 161                 if ((r = mount_one(mount_table+i)) < 0)
 162                         return r;
 163
 164         return mount_cgroup_controllers();
 165 }