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 <fcntl.h>
  24 #include <stdbool.h>
  25 #include <stdlib.h>
  26 #include <sys/stat.h>
  27 #include <syslog.h>
  28 #include <unistd.h>
  29
  30 #include "alloc-util.h"
  31 #include "base-filesystem.h"
  32 #include "fd-util.h"
  33 #include "log.h"
  34 #include "macro.h"
  35 #include "string-util.h"
  36 #include "umask-util.h"
  37 #include "user-util.h"
  38 #include "util.h"
  39
  40 typedef struct BaseFilesystem {
  41         const char *dir;
  42         mode_t mode;
  43         const char *target;
  44         const char *exists;
  45         bool ignore_failure;
  46 } BaseFilesystem;
  47
  48 static const BaseFilesystem table[] = {
  49         { "bin",      0, "usr/bin\0",                  NULL },
  50         { "lib",      0, "usr/lib\0",                  NULL },
  51         { "root",  0755, NULL,                         NULL, true },
  52         { "sbin",     0, "usr/sbin\0",                 NULL },
  53         { "usr",   0755, NULL,                         NULL },
  54         { "var",   0755, NULL,                         NULL },
  55         { "etc",   0755, NULL,                         NULL },
  56 #if defined(__i386__) || defined(__x86_64__)
  57         { "lib64",    0, "usr/lib/x86_64-linux-gnu\0"
  58                          "usr/lib64\0",                "ld-linux-x86-64.so.2" },
  59 #endif
  60 };
  61
  62 int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
  63         _cleanup_close_ int fd = -1;
  64         unsigned i;
  65         int r = 0;
  66
  67         fd = open(root, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
  68         if (fd < 0)
  69                 return log_error_errno(errno, "Failed to open root file system: %m");
  70
  71         for (i = 0; i < ELEMENTSOF(table); i ++) {
  72                 if (faccessat(fd, table[i].dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0)
  73                         continue;
  74
  75                 if (table[i].target) {
  76                         const char *target = NULL, *s;
  77
  78                         /* check if one of the targets exists */
  79                         NULSTR_FOREACH(s, table[i].target) {
  80                                 if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  81                                         continue;
  82
  83                                 /* check if a specific file exists at the target path */
  84                                 if (table[i].exists) {
  85                                         _cleanup_free_ char *p = NULL;
  86
  87                                         p = strjoin(s, "/", table[i].exists, NULL);
  88                                         if (!p)
  89                                                 return log_oom();
  90
  91                                         if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
  92                                                 continue;
  93                                 }
  94
  95                                 target = s;
  96                                 break;
  97                         }
  98
  99                         if (!target)
 100                                 continue;
 101
 102                         r = symlinkat(target, fd, table[i].dir);
 103                         if (r < 0 && errno != EEXIST)
 104                                 return log_error_errno(errno, "Failed to create symlink at %s/%s: %m", root, table[i].dir);
 105
 106                         if (uid != UID_INVALID || gid != UID_INVALID) {
 107                                 if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 108                                         return log_error_errno(errno, "Failed to chown symlink at %s/%s: %m", root, table[i].dir);
 109                         }
 110
 111                         continue;
 112                 }
 113
 114                 RUN_WITH_UMASK(0000)
 115                         r = mkdirat(fd, table[i].dir, table[i].mode);
 116                 if (r < 0 && errno != EEXIST) {
 117                         log_full_errno(table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno,
 118                                        "Failed to create directory at %s/%s: %m", root, table[i].dir);
 119
 120                         if (!table[i].ignore_failure)
 121                                 return -errno;
 122                 }
 123
 124                 if (uid != UID_INVALID || gid != UID_INVALID) {
 125                         if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
 126                                 return log_error_errno(errno, "Failed to chown directory at %s/%s: %m", root, table[i].dir);
 127                 }
 128         }
 129
 130         return 0;
 131 }