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fd83c98e8a462b9b5ae07e3d7a2ace500b50c172
systemd/src/shared/blockdev-util.c
T
Yu Watanabe fd690a4b7f blockdev-util: introduce block_device_new_from_fd() and block_device_new_from_path() 
These are possible replacements of get_block_device(),
get_block_device_harder(), path_get_whole_disk(), and friends.
2022-09-28 17:42:23 +09:00

791 lines
22 KiB
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <linux/blkpg.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <unistd.h>
#include "sd-device.h"
#include "alloc-util.h"
#include "blockdev-util.h"
#include "btrfs-util.h"
#include "device-util.h"
#include "devnum-util.h"
#include "dirent-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "missing_magic.h"
#include "parse-util.h"
static int fd_get_devnum(int fd, BlockDeviceLookupFlag flags, dev_t *ret) {
struct stat st;
dev_t devnum;
int r;
assert(fd >= 0);
assert(ret);
if (fstat(fd, &st) < 0)
return -errno;
if (S_ISBLK(st.st_mode))
devnum = st.st_rdev;
else if (!FLAGS_SET(flags, BLOCK_DEVICE_LOOKUP_BACKING))
return -ENOTBLK;
else if (!S_ISREG(st.st_mode) && !S_ISDIR(st.st_mode))
return -ENOTBLK;
else if (major(st.st_dev) != 0)
devnum = st.st_dev;
else {
/* If major(st.st_dev) is zero, this might mean we are backed by btrfs, which needs special
* handing, to get the backing device node. */
r = fcntl(fd, F_GETFL);
if (r < 0)
return -errno;
if (FLAGS_SET(r, O_PATH)) {
_cleanup_close_ int regfd = -1;
/* The fstat() above we can execute on an O_PATH fd. But the btrfs ioctl we cannot.
* Hence acquire a "real" fd first, without the O_PATH flag. */
regfd = fd_reopen(fd, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (regfd < 0)
return regfd;
r = btrfs_get_block_device_fd(regfd, &devnum);
} else
r = btrfs_get_block_device_fd(fd, &devnum);
if (r == -ENOTTY) /* not btrfs */
return -ENOTBLK;
if (r < 0)
return r;
}
*ret = devnum;
return 0;
}
int block_device_is_whole_disk(sd_device *dev) {
const char *s;
int r;
assert(dev);
r = sd_device_get_subsystem(dev, &s);
if (r < 0)
return r;
if (!streq(s, "block"))
return -ENOTBLK;
r = sd_device_get_devtype(dev, &s);
if (r < 0)
return r;
return streq(s, "disk");
}
int block_device_get_whole_disk(sd_device *dev, sd_device **ret) {
int r;
assert(dev);
assert(ret);
/* Do not unref returned sd_device object. */
r = block_device_is_whole_disk(dev);
if (r < 0)
return r;
if (r == 0) {
r = sd_device_get_parent(dev, &dev);
if (r == -ENOENT) /* Already removed? Let's return a recognizable error. */
return -ENODEV;
if (r < 0)
return r;
r = block_device_is_whole_disk(dev);
if (r < 0)
return r;
if (r == 0)
return -ENXIO;
}
*ret = dev;
return 0;
}
static int block_device_get_originating(sd_device *dev, sd_device **ret) {
_cleanup_(sd_device_unrefp) sd_device *first_found = NULL;
const char *suffix;
sd_device *child;
dev_t devnum = 0; /* avoid false maybe-uninitialized warning */
/* For the specified block device tries to chase it through the layers, in case LUKS-style DM
* stacking is used, trying to find the next underlying layer. */
assert(dev);
assert(ret);
FOREACH_DEVICE_CHILD_WITH_SUFFIX(dev, child, suffix) {
sd_device *child_whole_disk;
dev_t n;
if (!path_startswith(suffix, "slaves"))
continue;
if (block_device_get_whole_disk(child, &child_whole_disk) < 0)
continue;
if (sd_device_get_devnum(child_whole_disk, &n) < 0)
continue;
if (!first_found) {
first_found = sd_device_ref(child);
devnum = n;
continue;
}
/* We found a device backed by multiple other devices. We don't really support automatic
* discovery on such setups, with the exception of dm-verity partitions. In this case there
* are two backing devices: the data partition and the hash partition. We are fine with such
* setups, however, only if both partitions are on the same physical device. Hence, let's
* verify this by iterating over every node in the 'slaves/' directory and comparing them with
* the first that gets returned by readdir(), to ensure they all point to the same device. */
if (n != devnum)
return -ENOTUNIQ;
}
if (!first_found)
return -ENOENT;
*ret = TAKE_PTR(first_found);
return 1; /* found */
}
int block_device_new_from_fd(int fd, BlockDeviceLookupFlag flags, sd_device **ret) {
_cleanup_(sd_device_unrefp) sd_device *dev = NULL;
dev_t devnum;
int r;
assert(fd >= 0);
assert(ret);
r = fd_get_devnum(fd, flags, &devnum);
if (r < 0)
return r;
r = sd_device_new_from_devnum(&dev, 'b', devnum);
if (r < 0)
return r;
if (FLAGS_SET(flags, BLOCK_DEVICE_LOOKUP_ORIGINATING)) {
_cleanup_(sd_device_unrefp) sd_device *dev_origin = NULL;
sd_device *dev_whole_disk;
r = block_device_get_whole_disk(dev, &dev_whole_disk);
if (r < 0)
return r;
r = block_device_get_originating(dev_whole_disk, &dev_origin);
if (r < 0 && r != -ENOENT)
return r;
if (r > 0)
device_unref_and_replace(dev, dev_origin);
}
if (FLAGS_SET(flags, BLOCK_DEVICE_LOOKUP_WHOLE_DISK)) {
sd_device *dev_whole_disk;
r = block_device_get_whole_disk(dev, &dev_whole_disk);
if (r < 0)
return r;
*ret = sd_device_ref(dev_whole_disk);
return 0;
}
*ret = sd_device_ref(dev);
return 0;
}
int block_device_new_from_path(const char *path, BlockDeviceLookupFlag flags, sd_device **ret) {
_cleanup_close_ int fd = -1;
assert(path);
assert(ret);
fd = open(path, O_CLOEXEC|O_PATH);
if (fd < 0)
return -errno;
return block_device_new_from_fd(fd, flags, ret);
}
int block_get_whole_disk(dev_t d, dev_t *ret) {
char p[SYS_BLOCK_PATH_MAX("/partition")];
_cleanup_free_ char *s = NULL;
dev_t devt;
int r;
assert(ret);
if (major(d) == 0)
return -ENODEV;
/* If it has a queue this is good enough for us */
xsprintf_sys_block_path(p, "/queue", d);
if (access(p, F_OK) >= 0) {
*ret = d;
return 0;
}
if (errno != ENOENT)
return -errno;
/* If it is a partition find the originating device */
xsprintf_sys_block_path(p, "/partition", d);
if (access(p, F_OK) < 0)
return -errno;
/* Get parent dev_t */
xsprintf_sys_block_path(p, "/../dev", d);
r = read_one_line_file(p, &s);
if (r < 0)
return r;
r = parse_devnum(s, &devt);
if (r < 0)
return r;
/* Only return this if it is really good enough for us. */
xsprintf_sys_block_path(p, "/queue", devt);
if (access(p, F_OK) < 0)
return -errno;
*ret = devt;
return 1;
}
int get_block_device_fd(int fd, dev_t *ret) {
struct stat st;
int r;
assert(fd >= 0);
assert(ret);
/* Gets the block device directly backing a file system. If the block device is encrypted, returns
* the device mapper block device. */
if (fstat(fd, &st))
return -errno;
if (major(st.st_dev) != 0) {
*ret = st.st_dev;
return 1;
}
r = fcntl(fd, F_GETFL);
if (r < 0)
return -errno;
if (FLAGS_SET(r, O_PATH) && (S_ISREG(st.st_mode) || S_ISDIR(st.st_mode))) {
_cleanup_close_ int real_fd = -1;
/* The fstat() above we can execute on an O_PATH fd. But the btrfs ioctl we cannot. Hence
* acquire a "real" fd first, without the O_PATH flag. */
real_fd = fd_reopen(fd, O_RDONLY|O_CLOEXEC);
if (real_fd < 0)
return real_fd;
r = btrfs_get_block_device_fd(real_fd, ret);
} else
r = btrfs_get_block_device_fd(fd, ret);
if (r > 0)
return 1;
if (r != -ENOTTY) /* not btrfs */
return r;
*ret = 0;
return 0;
}
int get_block_device(const char *path, dev_t *ret) {
_cleanup_close_ int fd = -1;
assert(path);
assert(ret);
fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
if (fd < 0)
return -errno;
return get_block_device_fd(fd, ret);
}
int block_get_originating(dev_t dt, dev_t *ret) {
_cleanup_(sd_device_unrefp) sd_device *dev = NULL, *origin = NULL;
int r;
assert(ret);
r = sd_device_new_from_devnum(&dev, 'b', dt);
if (r < 0)
return r;
r = block_device_get_originating(dev, &origin);
if (r < 0)
return r;
return sd_device_get_devnum(origin, ret);
}
int get_block_device_harder_fd(int fd, dev_t *ret) {
int r;
assert(fd >= 0);
assert(ret);
/* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
* immediate parent, if there is one. */
r = get_block_device_fd(fd, ret);
if (r <= 0)
return r;
r = block_get_originating(*ret, ret);
if (r < 0)
log_debug_errno(r, "Failed to chase block device, ignoring: %m");
return 1;
}
int get_block_device_harder(const char *path, dev_t *ret) {
_cleanup_close_ int fd = -1;
assert(path);
assert(ret);
fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
if (fd < 0)
return -errno;
return get_block_device_harder_fd(fd, ret);
}
int lock_whole_block_device(dev_t devt, int operation) {
_cleanup_close_ int lock_fd = -1;
dev_t whole_devt;
int r;
/* Let's get a BSD file lock on the whole block device, as per: https://systemd.io/BLOCK_DEVICE_LOCKING */
r = block_get_whole_disk(devt, &whole_devt);
if (r < 0)
return r;
lock_fd = r = device_open_from_devnum(S_IFBLK, whole_devt, O_RDONLY|O_CLOEXEC|O_NONBLOCK, NULL);
if (r < 0)
return r;
if (flock(lock_fd, operation) < 0)
return -errno;
return TAKE_FD(lock_fd);
}
int blockdev_partscan_enabled(int fd) {
_cleanup_free_ char *p = NULL, *buf = NULL;
unsigned long long ull;
struct stat st;
int r;
/* Checks if partition scanning is correctly enabled on the block device */
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
return -ENOMEM;
r = read_one_line_file(p, &buf);
if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
* partition block device, not the whole block device. And that means we have no
* partition scanning on for it (we do for its parent, but not for the partition
* itself). */
return false;
if (r < 0)
return r;
r = safe_atollu_full(buf, 16, &ull);
if (r < 0)
return r;
#ifndef GENHD_FL_NO_PART_SCAN
#define GENHD_FL_NO_PART_SCAN (0x0200)
#endif
return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
}
static int blockdev_is_encrypted(const char *sysfs_path, unsigned depth_left) {
_cleanup_free_ char *p = NULL, *uuids = NULL;
_cleanup_closedir_ DIR *d = NULL;
int r, found_encrypted = false;
assert(sysfs_path);
if (depth_left == 0)
return -EINVAL;
p = path_join(sysfs_path, "dm/uuid");
if (!p)
return -ENOMEM;
r = read_one_line_file(p, &uuids);
if (r != -ENOENT) {
if (r < 0)
return r;
/* The DM device's uuid attribute is prefixed with "CRYPT-" if this is a dm-crypt device. */
if (startswith(uuids, "CRYPT-"))
return true;
}
/* Not a dm-crypt device itself. But maybe it is on top of one? Follow the links in the "slaves/"
* subdir. */
p = mfree(p);
p = path_join(sysfs_path, "slaves");
if (!p)
return -ENOMEM;
d = opendir(p);
if (!d) {
if (errno == ENOENT) /* Doesn't have underlying devices */
return false;
return -errno;
}
for (;;) {
_cleanup_free_ char *q = NULL;
struct dirent *de;
errno = 0;
de = readdir_no_dot(d);
if (!de) {
if (errno != 0)
return -errno;
break; /* No more underlying devices */
}
q = path_join(p, de->d_name);
if (!q)
return -ENOMEM;
r = blockdev_is_encrypted(q, depth_left - 1);
if (r < 0)
return r;
if (r == 0) /* we found one that is not encrypted? then propagate that immediately */
return false;
found_encrypted = true;
}
return found_encrypted;
}
int fd_is_encrypted(int fd) {
char p[SYS_BLOCK_PATH_MAX(NULL)];
dev_t devt;
int r;
r = get_block_device_fd(fd, &devt);
if (r < 0)
return r;
if (r == 0) /* doesn't have a block device */
return false;
xsprintf_sys_block_path(p, NULL, devt);
return blockdev_is_encrypted(p, 10 /* safety net: maximum recursion depth */);
}
int path_is_encrypted(const char *path) {
char p[SYS_BLOCK_PATH_MAX(NULL)];
dev_t devt;
int r;
r = get_block_device(path, &devt);
if (r < 0)
return r;
if (r == 0) /* doesn't have a block device */
return false;
xsprintf_sys_block_path(p, NULL, devt);
return blockdev_is_encrypted(p, 10 /* safety net: maximum recursion depth */);
}
int fd_get_whole_disk(int fd, bool backing, dev_t *ret) {
dev_t devt;
int r;
assert(fd >= 0);
assert(ret);
r = fd_get_devnum(fd, backing ? BLOCK_DEVICE_LOOKUP_BACKING : 0, &devt);
if (r < 0)
return r;
return block_get_whole_disk(devt, ret);
}
int path_get_whole_disk(const char *path, bool backing, dev_t *ret) {
_cleanup_close_ int fd = -1;
fd = open(path, O_CLOEXEC|O_PATH);
if (fd < 0)
return -errno;
return fd_get_whole_disk(fd, backing, ret);
}
int block_device_add_partition(
int fd,
const char *name,
int nr,
uint64_t start,
uint64_t size) {
assert(fd >= 0);
assert(name);
assert(nr > 0);
struct blkpg_partition bp = {
.pno = nr,
.start = start,
.length = size,
};
struct blkpg_ioctl_arg ba = {
.op = BLKPG_ADD_PARTITION,
.data = &bp,
.datalen = sizeof(bp),
};
if (strlen(name) >= sizeof(bp.devname))
return -EINVAL;
strcpy(bp.devname, name);
return RET_NERRNO(ioctl(fd, BLKPG, &ba));
}
int block_device_remove_partition(
int fd,
const char *name,
int nr) {
assert(fd >= 0);
assert(name);
assert(nr > 0);
struct blkpg_partition bp = {
.pno = nr,
};
struct blkpg_ioctl_arg ba = {
.op = BLKPG_DEL_PARTITION,
.data = &bp,
.datalen = sizeof(bp),
};
if (strlen(name) >= sizeof(bp.devname))
return -EINVAL;
strcpy(bp.devname, name);
return RET_NERRNO(ioctl(fd, BLKPG, &ba));
}
int block_device_resize_partition(
int fd,
int nr,
uint64_t start,
uint64_t size) {
assert(fd >= 0);
assert(nr > 0);
struct blkpg_partition bp = {
.pno = nr,
.start = start,
.length = size,
};
struct blkpg_ioctl_arg ba = {
.op = BLKPG_RESIZE_PARTITION,
.data = &bp,
.datalen = sizeof(bp),
};
return RET_NERRNO(ioctl(fd, BLKPG, &ba));
}
int partition_enumerator_new(sd_device *dev, sd_device_enumerator **ret) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
const char *s;
int r;
assert(dev);
assert(ret);
/* Refuse invocation on partition block device, insist on "whole" device */
r = block_device_is_whole_disk(dev);
if (r < 0)
return r;
if (r == 0)
return -ENXIO; /* return a recognizable error */
r = sd_device_enumerator_new(&e);
if (r < 0)
return r;
r = sd_device_enumerator_allow_uninitialized(e);
if (r < 0)
return r;
r = sd_device_enumerator_add_match_parent(e, dev);
if (r < 0)
return r;
r = sd_device_get_sysname(dev, &s);
if (r < 0)
return r;
/* Also add sysname check for safety. Hopefully, this also improves performance. */
s = strjoina(s, "*");
r = sd_device_enumerator_add_match_sysname(e, s);
if (r < 0)
return r;
r = sd_device_enumerator_add_match_subsystem(e, "block", /* match = */ true);
if (r < 0)
return r;
r = sd_device_enumerator_add_match_property(e, "DEVTYPE", "partition");
if (r < 0)
return r;
*ret = TAKE_PTR(e);
return 0;
}
int block_device_remove_all_partitions(sd_device *dev, int fd) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
_cleanup_(sd_device_unrefp) sd_device *dev_unref = NULL;
_cleanup_close_ int fd_close = -1;
bool has_partitions = false;
sd_device *part;
int r, k = 0;
assert(dev || fd >= 0);
if (!dev) {
r = block_device_new_from_fd(fd, 0, &dev_unref);
if (r < 0)
return r;
dev = dev_unref;
}
r = partition_enumerator_new(dev, &e);
if (r < 0)
return r;
if (fd < 0) {
fd_close = sd_device_open(dev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|O_RDONLY);
if (fd_close < 0)
return fd_close;
fd = fd_close;
}
FOREACH_DEVICE(e, part) {
const char *v, *devname;
int nr;
has_partitions = true;
r = sd_device_get_devname(part, &devname);
if (r < 0)
return r;
r = sd_device_get_property_value(part, "PARTN", &v);
if (r < 0)
return r;
r = safe_atoi(v, &nr);
if (r < 0)
return r;
r = block_device_remove_partition(fd, devname, nr);
if (r == -ENODEV) {
log_debug("Kernel removed partition %s before us, ignoring", devname);
continue;
}
if (r < 0) {
log_debug_errno(r, "Failed to remove partition %s: %m", devname);
k = k < 0 ? k : r;
continue;
}
log_debug("Removed partition %s", devname);
}
return k < 0 ? k : has_partitions;
}
int block_device_has_partitions(sd_device *dev) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
int r;
assert(dev);
/* Checks if the specified device currently has partitions. */
r = partition_enumerator_new(dev, &e);
if (r < 0)
return r;
return !!sd_device_enumerator_get_device_first(e);
}
int blockdev_reread_partition_table(sd_device *dev) {
_cleanup_close_ int fd = -1;
assert(dev);
/* Try to re-read the partition table. This only succeeds if none of the devices is busy. */
fd = sd_device_open(dev, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (fd < 0)
return fd;
if (flock(fd, LOCK_EX|LOCK_NB) < 0)
return -errno;
if (ioctl(fd, BLKRRPART, 0) < 0)
return -errno;
return 0;
}
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