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/*
* Linux block devices helpers
*
* Copyright (C) 2018-2021 Red Hat, Inc. All rights reserved.
* Copyright (C) 2018-2021 Ondrej Kozina
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "cryptsetup.h"
#include <dirent.h>
#ifdef HAVE_SYS_SYSMACROS_H
# include <sys/sysmacros.h> /* for major, minor */
#endif
#include <uuid/uuid.h>
#define DM_UUID_LEN 129
#define DM_BY_ID_PREFIX "dm-uuid-"
#define DM_BY_ID_PREFIX_LEN 8
#define DM_UUID_PREFIX "CRYPT-"
#define DM_UUID_PREFIX_LEN 6
#define UUID_LEN 37 /* 36 + \0, libuuid ... */
static int dm_prepare_uuid(const char *type, const char *uuid, char *buf, size_t buflen)
{
char *ptr, uuid2[UUID_LEN] = {0};
uuid_t uu;
unsigned i = 0;
/* Remove '-' chars */
if (uuid) {
if (uuid_parse(uuid, uu) < 0) {
log_dbg("Requested UUID %s has invalid format.", uuid);
return 0;
}
for (ptr = uuid2, i = 0; i < UUID_LEN; i++)
if (uuid[i] != '-') {
*ptr = uuid[i];
ptr++;
}
}
snprintf(buf, buflen, DM_UUID_PREFIX "%s%s%s%s",
type ?: "", type ? "-" : "",
uuid2[0] ? uuid2 : "", uuid2[0] ? "-" : "");
return 1;
}
/* return number of holders in general, if matched dm_uuid prefix it's returned via dm_name */
/* negative value is error */
static int lookup_holder_dm_name(const char *dm_uuid, size_t max_len, dev_t devno, char *dm_name, size_t dm_name_length)
{
struct dirent *entry;
char dm_subpath[PATH_MAX], data_dev_dir[PATH_MAX], uuid[max_len];
ssize_t s;
struct stat st;
int dmfd, fd, len, r = 0; /* not found */
DIR *dir;
if (!dm_name || !dm_name_length)
return -EINVAL;
*dm_name = '\0';
len = snprintf(data_dev_dir, PATH_MAX, "/sys/dev/block/%u:%u/holders", major(devno), minor(devno));
if (len < 0 || len >= PATH_MAX)
return -EINVAL;
if (!(dir = opendir(data_dev_dir)))
/* map ENOTDIR to ENOENT we'll handle both errors same */
return errno == ENOTDIR ? -ENOENT : -errno;
while (r != 1 && (entry = readdir(dir))) {
if (entry->d_name[0] == '.' ||
!strncmp(entry->d_name, "..", 2))
continue;
/* there's a holder */
r++;
/* we already have a dm_name, just count remaining holders */
if (*dm_name != '\0')
continue;
len = snprintf(dm_subpath, PATH_MAX, "%s/%s", entry->d_name, "dm");
if (len < 0 || len >= PATH_MAX) {
r = -EINVAL;
break;
}
/* looking for dm-X/dm directory, symlinks are fine */
dmfd = openat(dirfd(dir), dm_subpath, O_DIRECTORY | O_RDONLY);
if (dmfd < 0)
continue;
fd = openat(dmfd, "uuid", O_RDONLY);
if (fd < 0) {
close(dmfd);
continue;
}
if (fstat(fd, &st) || !S_ISREG(st.st_mode)) {
close(fd);
close(dmfd);
continue;
}
/* reads binary data */
s = read_buffer(fd, uuid, max_len - 1);
close(fd);
uuid[s > 0 ? s : 0] = '\0';
if (!strncmp(uuid, dm_uuid, strlen(dm_uuid)))
log_dbg("Found candidate device %s", entry->d_name);
else {
close(dmfd);
continue;
}
fd = openat(dmfd, "name", O_RDONLY);
if (fd < 0) {
close(dmfd);
continue;
}
if (fstat(fd, &st) || !S_ISREG(st.st_mode)) {
close(fd);
close(dmfd);
continue;
}
/* reads binary data */
s = read_buffer(fd, dm_name, dm_name_length - 1);
close(fd);
close(dmfd);
if (s > 1) {
dm_name[s-1] = '\0';
log_dbg("Found dm device %s", dm_name);
}
}
closedir(dir);
return r;
}
int tools_lookup_crypt_device(struct crypt_device *cd, const char *type,
const char *data_device_path, char *name, size_t name_length)
{
int r;
char *c;
struct stat st;
char dev_uuid[DM_UUID_LEN + DM_BY_ID_PREFIX_LEN] = DM_BY_ID_PREFIX;
if (!dm_prepare_uuid(type, crypt_get_uuid(cd), dev_uuid + DM_BY_ID_PREFIX_LEN, DM_UUID_LEN))
return -EINVAL;
c = strrchr(dev_uuid, '-');
if (!c)
return -EINVAL;
/* cut of dm name */
*c = '\0';
log_dbg("Looking for any dm device with prefix: %s", dev_uuid);
if (stat(data_device_path, &st) < 0)
return -ENODEV;
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
r = lookup_holder_dm_name(dev_uuid + DM_BY_ID_PREFIX_LEN, DM_UUID_LEN,
st.st_rdev, name, name_length);
return r;
}
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