src/shared/base-filesystem.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Kay Sievers
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stdbool.h>
  23 #include <stdlib.h>
  24 #include <sys/stat.h>
  25 #include <syslog.h>
  26 #include <unistd.h>
  27
  28 #include "alloc-util.h"
  29 #include "base-filesystem.h"
  30 #include "fd-util.h"
  31 #include "log.h"
  32 #include "macro.h"
  33 #include "string-util.h"
  34 #include "umask-util.h"
  35 #include "user-util.h"
  36 #include "util.h"
  37
  38 typedef struct BaseFilesystem {
  39         const char *dir;
  40         mode_t mode;
  41         const char *target;
  42         const char *exists;
  43         bool ignore_failure;
  44 } BaseFilesystem;
  45
  46 static const BaseFilesystem table[] = {
  47         { "bin",      0, "usr/bin\0",                  NULL },
  48         { "lib",      0, "usr/lib\0",                  NULL },
  49         { "root",  0755, NULL,                         NULL, true },
  50         { "sbin",     0, "usr/sbin\0",                 NULL },
  51         { "usr",   0755, NULL,                         NULL },
  52         { "var",   0755, NULL,                         NULL },
  53         { "etc",   0755, NULL,                         NULL },
  54 #if defined(__i386__) || defined(__x86_64__)
  55         { "lib64",    0, "usr/lib/x86_64-linux-gnu\0"
  56                          "usr/lib64\0",                "ld-linux-x86-64.so.2" },
  57 #endif
  58 };
  59
  60 int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
  61         _cleanup_close_ int fd = -1;
  62         unsigned i;
  63         int r = 0;
  64
  65         fd = open(root, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
  66         if (fd < 0)
  67                 return log_error_errno(errno, "Failed to open root file system: %m");
  68
  69         for (i = 0; i < ELEMENTSOF(table); i ++) {
  70                 if (faccessat(fd, table[i].dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0)
  71                         continue;
  72
  73                 if (table[i].target) {
  74                         const char *target = NULL, *s;
  75
  76                         /* check if one of the targets exists */
  77                         NULSTR_FOREACH(s, table[i].target) {
  78                                 if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  79                                         continue;
  80
  81                                 /* check if a specific file exists at the target path */
  82                                 if (table[i].exists) {
  83                                         _cleanup_free_ char *p = NULL;
  84
  85                                         p = strjoin(s, "/", table[i].exists, NULL);
  86                                         if (!p)
  87                                                 return log_oom();
  88
  89                                         if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  90                                                 continue;
  91                                 }
  92
  93                                 target = s;
  94                                 break;
  95                         }
  96
  97                         if (!target)
  98                                 continue;
  99
 100                         r = symlinkat(target, fd, table[i].dir);
 101                         if (r < 0 && errno != EEXIST)
 102                                 return log_error_errno(errno, "Failed to create symlink at %s/%s: %m", root, table[i].dir);
 103
 104                         if (uid != UID_INVALID || gid != UID_INVALID) {
 105                                 if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 106                                         return log_error_errno(errno, "Failed to chown symlink at %s/%s: %m", root, table[i].dir);
 107                         }
 108
 109                         continue;
 110                 }
 111
 112                 RUN_WITH_UMASK(0000)
 113                         r = mkdirat(fd, table[i].dir, table[i].mode);
 114                 if (r < 0 && errno != EEXIST) {
 115                         log_full_errno(table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno,
 116                                        "Failed to create directory at %s/%s: %m", root, table[i].dir);
 117
 118                         if (!table[i].ignore_failure)
 119                                 return -errno;
 120                 }
 121
 122                 if (uid != UID_INVALID || gid != UID_INVALID) {
 123                         if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 124                                 return log_error_errno(errno, "Failed to chown directory at %s/%s: %m", root, table[i].dir);
 125                 }
 126         }
 127
 128         return 0;
 129 }