src/shared/base-filesystem.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2014 Kay Sievers
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <stdlib.h>
  24 #include <sys/stat.h>
  25 #include <unistd.h>
  26
  27 #include "alloc-util.h"
  28 #include "base-filesystem.h"
  29 #include "fd-util.h"
  30 #include "log.h"
  31 #include "macro.h"
  32 #include "string-util.h"
  33 #include "umask-util.h"
  34 #include "user-util.h"
  35 #include "util.h"
  36
  37 typedef struct BaseFilesystem {
  38         const char *dir;
  39         mode_t mode;
  40         const char *target;
  41         const char *exists;
  42         bool ignore_failure;
  43 } BaseFilesystem;
  44
  45 static const BaseFilesystem table[] = {
  46         { "bin",      0, "usr/bin\0",                  NULL },
  47         { "lib",      0, "usr/lib\0",                  NULL },
  48         { "root",  0755, NULL,                         NULL, true },
  49         { "sbin",     0, "usr/sbin\0",                 NULL },
  50         { "usr",   0755, NULL,                         NULL },
  51         { "var",   0755, NULL,                         NULL },
  52         { "etc",   0755, NULL,                         NULL },
  53 #if defined(__i386__) || defined(__x86_64__)
  54         { "lib64",    0, "usr/lib/x86_64-linux-gnu\0"
  55                          "usr/lib64\0",                "ld-linux-x86-64.so.2" },
  56 #endif
  57 };
  58
  59 int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
  60         _cleanup_close_ int fd = -1;
  61         unsigned i;
  62         int r = 0;
  63
  64         fd = open(root, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
  65         if (fd < 0)
  66                 return log_error_errno(errno, "Failed to open root file system: %m");
  67
  68         for (i = 0; i < ELEMENTSOF(table); i ++) {
  69                 if (faccessat(fd, table[i].dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0)
  70                         continue;
  71
  72                 if (table[i].target) {
  73                         const char *target = NULL, *s;
  74
  75                         /* check if one of the targets exists */
  76                         NULSTR_FOREACH(s, table[i].target) {
  77                                 if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  78                                         continue;
  79
  80                                 /* check if a specific file exists at the target path */
  81                                 if (table[i].exists) {
  82                                         _cleanup_free_ char *p = NULL;
  83
  84                                         p = strjoin(s, "/", table[i].exists, NULL);
  85                                         if (!p)
  86                                                 return log_oom();
  87
  88                                         if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  89                                                 continue;
  90                                 }
  91
  92                                 target = s;
  93                                 break;
  94                         }
  95
  96                         if (!target)
  97                                 continue;
  98
  99                         r = symlinkat(target, fd, table[i].dir);
 100                         if (r < 0 && errno != EEXIST)
 101                                 return log_error_errno(errno, "Failed to create symlink at %s/%s: %m", root, table[i].dir);
 102
 103                         if (uid != UID_INVALID || gid != UID_INVALID) {
 104                                 if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 105                                         return log_error_errno(errno, "Failed to chown symlink at %s/%s: %m", root, table[i].dir);
 106                         }
 107
 108                         continue;
 109                 }
 110
 111                 RUN_WITH_UMASK(0000)
 112                         r = mkdirat(fd, table[i].dir, table[i].mode);
 113                 if (r < 0 && errno != EEXIST) {
 114                         log_full_errno(table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno,
 115                                        "Failed to create directory at %s/%s: %m", root, table[i].dir);
 116
 117                         if (!table[i].ignore_failure)
 118                                 return -errno;
 119                 }
 120
 121                 if (uid != UID_INVALID || gid != UID_INVALID) {
 122                         if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 123                                 return log_error_errno(errno, "Failed to chown directory at %s/%s: %m", root, table[i].dir);
 124                 }
 125         }
 126
 127         return 0;
 128 }