diff options
Diffstat (limited to 'src/utils_blockdev.c')
| -rw-r--r-- | src/utils_blockdev.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/utils_blockdev.c b/src/utils_blockdev.c new file mode 100644 index 0000000..a96f309 --- /dev/null +++ b/src/utils_blockdev.c @@ -0,0 +1,189 @@ +/* + * 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; +} |