Line data Source code
1 : /* SPDX-License-Identifier: LGPL-2.1+ */
2 :
3 : #include <sys/stat.h>
4 : #include <sys/statfs.h>
5 :
6 : #include "alloc-util.h"
7 : #include "blockdev-util.h"
8 : #include "btrfs-util.h"
9 : #include "dirent-util.h"
10 : #include "fd-util.h"
11 : #include "fileio.h"
12 : #include "missing.h"
13 : #include "parse-util.h"
14 : #include "stat-util.h"
15 :
16 0 : int block_get_whole_disk(dev_t d, dev_t *ret) {
17 0 : char p[SYS_BLOCK_PATH_MAX("/partition")];
18 0 : _cleanup_free_ char *s = NULL;
19 : dev_t devt;
20 : int r;
21 :
22 0 : assert(ret);
23 :
24 0 : if (major(d) == 0)
25 0 : return -ENODEV;
26 :
27 : /* If it has a queue this is good enough for us */
28 0 : xsprintf_sys_block_path(p, "/queue", d);
29 0 : if (access(p, F_OK) >= 0) {
30 0 : *ret = d;
31 0 : return 0;
32 : }
33 :
34 : /* If it is a partition find the originating device */
35 0 : xsprintf_sys_block_path(p, "/partition", d);
36 0 : if (access(p, F_OK) < 0)
37 0 : return -errno;
38 :
39 : /* Get parent dev_t */
40 0 : xsprintf_sys_block_path(p, "/../dev", d);
41 0 : r = read_one_line_file(p, &s);
42 0 : if (r < 0)
43 0 : return r;
44 :
45 0 : r = parse_dev(s, &devt);
46 0 : if (r < 0)
47 0 : return r;
48 :
49 : /* Only return this if it is really good enough for us. */
50 0 : xsprintf_sys_block_path(p, "/queue", devt);
51 0 : if (access(p, F_OK) < 0)
52 0 : return -errno;
53 :
54 0 : *ret = devt;
55 0 : return 1;
56 : }
57 :
58 0 : int get_block_device(const char *path, dev_t *dev) {
59 : struct stat st;
60 : struct statfs sfs;
61 :
62 0 : assert(path);
63 0 : assert(dev);
64 :
65 : /* Gets the block device directly backing a file system. If
66 : * the block device is encrypted, returns the device mapper
67 : * block device. */
68 :
69 0 : if (lstat(path, &st))
70 0 : return -errno;
71 :
72 0 : if (major(st.st_dev) != 0) {
73 0 : *dev = st.st_dev;
74 0 : return 1;
75 : }
76 :
77 0 : if (statfs(path, &sfs) < 0)
78 0 : return -errno;
79 :
80 0 : if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
81 0 : return btrfs_get_block_device(path, dev);
82 :
83 0 : *dev = 0;
84 0 : return 0;
85 : }
86 :
87 0 : int block_get_originating(dev_t dt, dev_t *ret) {
88 0 : _cleanup_closedir_ DIR *d = NULL;
89 0 : _cleanup_free_ char *t = NULL;
90 0 : char p[SYS_BLOCK_PATH_MAX("/slaves")];
91 0 : struct dirent *de, *found = NULL;
92 : const char *q;
93 : dev_t devt;
94 : int r;
95 :
96 : /* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
97 : * trying to find the next underlying layer. */
98 :
99 0 : xsprintf_sys_block_path(p, "/slaves", dt);
100 0 : d = opendir(p);
101 0 : if (!d)
102 0 : return -errno;
103 :
104 0 : FOREACH_DIRENT_ALL(de, d, return -errno) {
105 :
106 0 : if (dot_or_dot_dot(de->d_name))
107 0 : continue;
108 :
109 0 : if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
110 0 : continue;
111 :
112 0 : if (found) {
113 0 : _cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
114 :
115 : /* We found a device backed by multiple other devices. We don't really support automatic
116 : * discovery on such setups, with the exception of dm-verity partitions. In this case there are
117 : * two backing devices: the data partition and the hash partition. We are fine with such
118 : * setups, however, only if both partitions are on the same physical device. Hence, let's
119 : * verify this. */
120 :
121 0 : u = path_join(p, de->d_name, "../dev");
122 0 : if (!u)
123 0 : return -ENOMEM;
124 :
125 0 : v = path_join(p, found->d_name, "../dev");
126 0 : if (!v)
127 0 : return -ENOMEM;
128 :
129 0 : r = read_one_line_file(u, &a);
130 0 : if (r < 0)
131 0 : return log_debug_errno(r, "Failed to read %s: %m", u);
132 :
133 0 : r = read_one_line_file(v, &b);
134 0 : if (r < 0)
135 0 : return log_debug_errno(r, "Failed to read %s: %m", v);
136 :
137 : /* Check if the parent device is the same. If not, then the two backing devices are on
138 : * different physical devices, and we don't support that. */
139 0 : if (!streq(a, b))
140 0 : return -ENOTUNIQ;
141 : }
142 :
143 0 : found = de;
144 : }
145 :
146 0 : if (!found)
147 0 : return -ENOENT;
148 :
149 0 : q = strjoina(p, "/", found->d_name, "/dev");
150 :
151 0 : r = read_one_line_file(q, &t);
152 0 : if (r < 0)
153 0 : return r;
154 :
155 0 : r = parse_dev(t, &devt);
156 0 : if (r < 0)
157 0 : return -EINVAL;
158 :
159 0 : if (major(devt) == 0)
160 0 : return -ENOENT;
161 :
162 0 : *ret = devt;
163 0 : return 1;
164 : }
165 :
166 0 : int get_block_device_harder(const char *path, dev_t *ret) {
167 : int r;
168 :
169 0 : assert(path);
170 0 : assert(ret);
171 :
172 : /* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
173 : * immediate parent, if there is one. */
174 :
175 0 : r = get_block_device(path, ret);
176 0 : if (r <= 0)
177 0 : return r;
178 :
179 0 : r = block_get_originating(*ret, ret);
180 0 : if (r < 0)
181 0 : log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
182 :
183 0 : return 1;
184 : }
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