src/basic/blockdev-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <unistd.h>
   4
   5 #include "alloc-util.h"
   6 #include "blockdev-util.h"
   7 #include "btrfs-util.h"
   8 #include "dirent-util.h"
   9 #include "fd-util.h"
  10 #include "fileio.h"
  11 #include "missing_magic.h"
  12 #include "parse-util.h"
  13 #include "stat-util.h"
  14
  15 int block_get_whole_disk(dev_t d, dev_t *ret) {
  16         char p[SYS_BLOCK_PATH_MAX("/partition")];
  17         _cleanup_free_ char *s = NULL;
  18         dev_t devt;
  19         int r;
  20
  21         assert(ret);
  22
  23         if (major(d) == 0)
  24                 return -ENODEV;
  25
  26         /* If it has a queue this is good enough for us */
  27         xsprintf_sys_block_path(p, "/queue", d);
  28         if (access(p, F_OK) >= 0) {
  29                 *ret = d;
  30                 return 0;
  31         }
  32
  33         /* If it is a partition find the originating device */
  34         xsprintf_sys_block_path(p, "/partition", d);
  35         if (access(p, F_OK) < 0)
  36                 return -errno;
  37
  38         /* Get parent dev_t */
  39         xsprintf_sys_block_path(p, "/../dev", d);
  40         r = read_one_line_file(p, &s);
  41         if (r < 0)
  42                 return r;
  43
  44         r = parse_dev(s, &devt);
  45         if (r < 0)
  46                 return r;
  47
  48         /* Only return this if it is really good enough for us. */
  49         xsprintf_sys_block_path(p, "/queue", devt);
  50         if (access(p, F_OK) < 0)
  51                 return -errno;
  52
  53         *ret = devt;
  54         return 1;
  55 }
  56
  57 int get_block_device(const char *path, dev_t *dev) {
  58         struct stat st;
  59         struct statfs sfs;
  60
  61         assert(path);
  62         assert(dev);
  63
  64         /* Gets the block device directly backing a file system. If
  65          * the block device is encrypted, returns the device mapper
  66          * block device. */
  67
  68         if (lstat(path, &st))
  69                 return -errno;
  70
  71         if (major(st.st_dev) != 0) {
  72                 *dev = st.st_dev;
  73                 return 1;
  74         }
  75
  76         if (statfs(path, &sfs) < 0)
  77                 return -errno;
  78
  79         if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
  80                 return btrfs_get_block_device(path, dev);
  81
  82         *dev = 0;
  83         return 0;
  84 }
  85
  86 int block_get_originating(dev_t dt, dev_t *ret) {
  87         _cleanup_closedir_ DIR *d = NULL;
  88         _cleanup_free_ char *t = NULL;
  89         char p[SYS_BLOCK_PATH_MAX("/slaves")];
  90         struct dirent *de, *found = NULL;
  91         const char *q;
  92         dev_t devt;
  93         int r;
  94
  95         /* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
  96          * trying to find the next underlying layer.  */
  97
  98         xsprintf_sys_block_path(p, "/slaves", dt);
  99         d = opendir(p);
 100         if (!d)
 101                 return -errno;
 102
 103         FOREACH_DIRENT_ALL(de, d, return -errno) {
 104
 105                 if (dot_or_dot_dot(de->d_name))
 106                         continue;
 107
 108                 if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
 109                         continue;
 110
 111                 if (found) {
 112                         _cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
 113
 114                         /* We found a device backed by multiple other devices. We don't really support automatic
 115                          * discovery on such setups, with the exception of dm-verity partitions. In this case there are
 116                          * two backing devices: the data partition and the hash partition. We are fine with such
 117                          * setups, however, only if both partitions are on the same physical device. Hence, let's
 118                          * verify this. */
 119
 120                         u = path_join(p, de->d_name, "../dev");
 121                         if (!u)
 122                                 return -ENOMEM;
 123
 124                         v = path_join(p, found->d_name, "../dev");
 125                         if (!v)
 126                                 return -ENOMEM;
 127
 128                         r = read_one_line_file(u, &a);
 129                         if (r < 0)
 130                                 return log_debug_errno(r, "Failed to read %s: %m", u);
 131
 132                         r = read_one_line_file(v, &b);
 133                         if (r < 0)
 134                                 return log_debug_errno(r, "Failed to read %s: %m", v);
 135
 136                         /* Check if the parent device is the same. If not, then the two backing devices are on
 137                          * different physical devices, and we don't support that. */
 138                         if (!streq(a, b))
 139                                 return -ENOTUNIQ;
 140                 }
 141
 142                 found = de;
 143         }
 144
 145         if (!found)
 146                 return -ENOENT;
 147
 148         q = strjoina(p, "/", found->d_name, "/dev");
 149
 150         r = read_one_line_file(q, &t);
 151         if (r < 0)
 152                 return r;
 153
 154         r = parse_dev(t, &devt);
 155         if (r < 0)
 156                 return -EINVAL;
 157
 158         if (major(devt) == 0)
 159                 return -ENOENT;
 160
 161         *ret = devt;
 162         return 1;
 163 }
 164
 165 int get_block_device_harder(const char *path, dev_t *ret) {
 166         int r;
 167
 168         assert(path);
 169         assert(ret);
 170
 171         /* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
 172          * immediate parent, if there is one. */
 173
 174         r = get_block_device(path, ret);
 175         if (r <= 0)
 176                 return r;
 177
 178         r = block_get_originating(*ret, ret);
 179         if (r < 0)
 180                 log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
 181
 182         return 1;
 183 }