685 lines
26 KiB
C
685 lines
26 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <fcntl.h>
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#include <sys/mount.h>
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#include "alloc-util.h"
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#include "chase.h"
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#include "errno-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "filesystems.h"
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#include "fs-util.h"
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#include "log.h"
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#include "mountpoint-util.h"
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#include "nulstr-util.h"
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#include "path-util.h"
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#include "stat-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "unaligned.h"
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/* This is the original MAX_HANDLE_SZ definition from the kernel, when the API was introduced. We use that in place of
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* any more currently defined value to future-proof things: if the size is increased in the API headers, and our code
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* is recompiled then it would cease working on old kernels, as those refuse any sizes larger than this value with
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* EINVAL right-away. Hence, let's disconnect ourselves from any such API changes, and stick to the original definition
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* from when it was introduced. We use it as a start value only anyway (see below), and hence should be able to deal
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* with large file handles anyway. */
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#define ORIGINAL_MAX_HANDLE_SZ 128
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bool is_name_to_handle_at_fatal_error(int err) {
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/* name_to_handle_at() can return "acceptable" errors that are due to the context. For example
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* the file system does not support name_to_handle_at() (EOPNOTSUPP), or the syscall was blocked
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* (EACCES/EPERM; maybe through seccomp, because we are running inside of a container), or
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* the mount point is not triggered yet (EOVERFLOW, think autofs+nfs4), or some general name_to_handle_at()
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* flakiness (EINVAL). However other errors are not supposed to happen and therefore are considered
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* fatal ones. */
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assert(err < 0);
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if (ERRNO_IS_NEG_NOT_SUPPORTED(err))
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return false;
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if (ERRNO_IS_NEG_PRIVILEGE(err))
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return false;
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return !IN_SET(err, -EOVERFLOW, -EINVAL);
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}
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int name_to_handle_at_loop(
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int fd,
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const char *path,
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struct file_handle **ret_handle,
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int *ret_mnt_id,
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uint64_t *ret_unique_mnt_id,
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int flags) {
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int r;
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assert(fd >= 0 || fd == AT_FDCWD);
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assert((flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH|AT_HANDLE_FID)) == 0);
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/* We need to invoke name_to_handle_at() in a loop, given that it might return EOVERFLOW when the specified
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* buffer is too small. Note that in contrast to what the docs might suggest, MAX_HANDLE_SZ is only good as a
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* start value, it is not an upper bound on the buffer size required.
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*
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* This improves on raw name_to_handle_at() also in one other regard: ret_handle and ret_mnt_id can be passed
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* as NULL if there's no interest in either.
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*
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* If unique mount id is requested via ret_unique_mnt_id, try AT_HANDLE_MNT_ID_UNIQUE flag first
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* (needs kernel v6.12), and fall back to statx() if not supported. If neither worked, and caller
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* also specifies ret_mnt_id, then the old-style mount id is returned, -EUNATCH otherwise. */
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if (isempty(path)) {
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flags |= AT_EMPTY_PATH;
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path = "";
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}
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for (size_t n = ORIGINAL_MAX_HANDLE_SZ;;) {
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_cleanup_free_ struct file_handle *h = NULL;
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h = malloc0(offsetof(struct file_handle, f_handle) + n);
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if (!h)
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return -ENOMEM;
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h->handle_bytes = n;
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if (ret_unique_mnt_id) {
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uint64_t mnt_id;
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/* The kernel will still use this as uint64_t pointer */
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r = name_to_handle_at(fd, path, h, (int *) &mnt_id, flags|AT_HANDLE_MNT_ID_UNIQUE);
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if (r >= 0) {
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if (ret_handle)
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*ret_handle = TAKE_PTR(h);
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*ret_unique_mnt_id = mnt_id;
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if (ret_mnt_id)
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*ret_mnt_id = -1;
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return 1;
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}
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if (errno == EOVERFLOW)
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goto grow;
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if (errno != EINVAL)
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return -errno;
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}
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int mnt_id;
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r = name_to_handle_at(fd, path, h, &mnt_id, flags);
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if (r >= 0) {
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if (ret_unique_mnt_id) {
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/* Hmm, AT_HANDLE_MNT_ID_UNIQUE is not supported? Let's try to acquire
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* the unique mount id from statx() then, which has a slightly lower
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* kernel version requirement (6.8 vs 6.12). */
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struct statx sx;
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r = xstatx(fd, path,
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at_flags_normalize_nofollow(flags & (AT_SYMLINK_FOLLOW|AT_EMPTY_PATH))|AT_STATX_DONT_SYNC,
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STATX_MNT_ID_UNIQUE,
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&sx);
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if (r >= 0) {
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if (ret_handle)
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*ret_handle = TAKE_PTR(h);
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*ret_unique_mnt_id = sx.stx_mnt_id;
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if (ret_mnt_id)
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*ret_mnt_id = -1;
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return 1;
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}
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if (r != -EUNATCH || !ret_mnt_id)
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return r;
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*ret_unique_mnt_id = 0;
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}
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if (ret_handle)
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*ret_handle = TAKE_PTR(h);
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if (ret_mnt_id)
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*ret_mnt_id = mnt_id;
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return 0;
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}
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if (errno != EOVERFLOW)
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return -errno;
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grow:
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/* If name_to_handle_at() didn't increase the byte size, then this EOVERFLOW is caused by
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* something else (apparently EOVERFLOW is returned for untriggered nfs4 autofs mounts
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* sometimes), not by the too small buffer. In that case propagate EOVERFLOW */
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if (h->handle_bytes <= n)
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return -EOVERFLOW;
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/* The buffer was too small. Size the new buffer by what name_to_handle_at() returned. */
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n = h->handle_bytes;
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/* paranoia: check for overflow (note that .handle_bytes is unsigned only) */
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if (n > UINT_MAX - offsetof(struct file_handle, f_handle))
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return -EOVERFLOW;
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}
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}
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int name_to_handle_at_try_fid(
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int fd,
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const char *path,
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struct file_handle **ret_handle,
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int *ret_mnt_id,
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uint64_t *ret_unique_mnt_id,
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int flags) {
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int r;
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assert(fd >= 0 || fd == AT_FDCWD);
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/* First issues name_to_handle_at() with AT_HANDLE_FID. If this fails and this is not a fatal error
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* we'll try without the flag, in order to support older kernels that didn't have AT_HANDLE_FID
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* (i.e. older than Linux 6.5). */
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r = name_to_handle_at_loop(fd, path, ret_handle, ret_mnt_id, ret_unique_mnt_id, flags | AT_HANDLE_FID);
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if (r >= 0 || is_name_to_handle_at_fatal_error(r))
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return r;
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return name_to_handle_at_loop(fd, path, ret_handle, ret_mnt_id, ret_unique_mnt_id, flags & ~AT_HANDLE_FID);
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}
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int name_to_handle_at_u64(int fd, const char *path, uint64_t *ret) {
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_cleanup_free_ struct file_handle *h = NULL;
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int r;
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assert(fd >= 0 || fd == AT_FDCWD);
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/* This provides the first 64bit of the file handle. */
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r = name_to_handle_at_loop(fd, path, &h, /* ret_mnt_id= */ NULL, /* ret_unique_mnt_id= */ NULL, /* flags= */ 0);
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if (r < 0)
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return r;
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if (h->handle_bytes < sizeof(uint64_t))
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return -EBADMSG;
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if (ret)
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/* Note, "struct file_handle" is 32bit aligned usually, but we need to read a 64bit value from it */
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*ret = unaligned_read_ne64(h->f_handle);
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return 0;
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}
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bool file_handle_equal(const struct file_handle *a, const struct file_handle *b) {
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if (a == b)
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return true;
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if (!a != !b)
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return false;
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if (a->handle_type != b->handle_type)
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return false;
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return memcmp_nn(a->f_handle, a->handle_bytes, b->f_handle, b->handle_bytes) == 0;
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}
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struct file_handle* file_handle_dup(const struct file_handle *fh) {
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_cleanup_free_ struct file_handle *fh_copy = NULL;
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assert(fh);
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fh_copy = malloc0(offsetof(struct file_handle, f_handle) + fh->handle_bytes);
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if (!fh_copy)
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return NULL;
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fh_copy->handle_bytes = fh->handle_bytes;
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fh_copy->handle_type = fh->handle_type;
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memcpy(fh_copy->f_handle, fh->f_handle, fh->handle_bytes);
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return TAKE_PTR(fh_copy);
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}
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int is_mount_point_at(int dir_fd, const char *path, int flags) {
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int r;
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assert(dir_fd >= 0 || IN_SET(dir_fd, AT_FDCWD, XAT_FDROOT));
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assert((flags & ~AT_SYMLINK_FOLLOW) == 0);
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if (path_equal(path, "/"))
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return true;
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if (dir_fd == XAT_FDROOT && isempty(path))
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return true;
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struct statx sx;
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r = xstatx_full(dir_fd, path,
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at_flags_normalize_nofollow(flags) |
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AT_NO_AUTOMOUNT | /* don't trigger automounts – mounts are a local concept, hence no need to trigger automounts to determine STATX_ATTR_MOUNT_ROOT */
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AT_STATX_DONT_SYNC, /* don't go to the network for this – for similar reasons */
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/* xstatx_flags = */ 0,
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STATX_TYPE|STATX_INO,
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/* optional_mask = */ 0,
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STATX_ATTR_MOUNT_ROOT,
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&sx);
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if (r < 0)
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return r;
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if (FLAGS_SET(sx.stx_attributes, STATX_ATTR_MOUNT_ROOT))
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return true;
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/* When running on chroot environment, the root may not be a mount point, but we unconditionally
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* return true when the input is "/" in the above, but the shortcut may not work e.g. when the path
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* is relative. */
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struct statx sx2;
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r = xstatx(AT_FDCWD,
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"/",
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AT_STATX_DONT_SYNC,
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STATX_TYPE|STATX_INO,
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&sx2);
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if (r < 0)
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return r;
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return statx_inode_same(&sx, &sx2);
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}
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/* flags can be AT_SYMLINK_FOLLOW or 0 */
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int path_is_mount_point_full(const char *path, const char *root, int flags) {
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_cleanup_close_ int dir_fd = -EBADF;
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int r;
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assert(path);
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assert((flags & ~AT_SYMLINK_FOLLOW) == 0);
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if (empty_or_root(root))
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return is_mount_point_at(AT_FDCWD, path, flags);
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r = chase(path, root,
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FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? 0 : CHASE_NOFOLLOW,
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/* ret_path= */ NULL, &dir_fd);
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if (r < 0)
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return r;
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return is_mount_point_at(dir_fd, /* path= */ NULL, flags);
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}
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static int path_get_mnt_id_at_internal(int dir_fd, const char *path, bool unique, uint64_t *ret) {
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struct statx sx;
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int r;
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assert(dir_fd >= 0 || IN_SET(dir_fd, AT_FDCWD, XAT_FDROOT));
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assert(ret);
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r = xstatx(dir_fd, path,
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AT_SYMLINK_NOFOLLOW |
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AT_NO_AUTOMOUNT | /* don't trigger automounts, mnt_id is a local concept */
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AT_STATX_DONT_SYNC, /* don't go to the network, mnt_id is a local concept */
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unique ? STATX_MNT_ID_UNIQUE : STATX_MNT_ID,
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&sx);
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if (r < 0)
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return r;
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*ret = sx.stx_mnt_id;
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return 0;
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}
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int path_get_mnt_id_at(int dir_fd, const char *path, int *ret) {
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uint64_t mnt_id;
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int r;
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r = path_get_mnt_id_at_internal(dir_fd, path, /* unique = */ false, &mnt_id);
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if (r < 0)
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return r;
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assert(mnt_id <= INT_MAX);
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*ret = (int) mnt_id;
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return 0;
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}
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int path_get_unique_mnt_id_at(int dir_fd, const char *path, uint64_t *ret) {
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return path_get_mnt_id_at_internal(dir_fd, path, /* unique = */ true, ret);
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}
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bool fstype_is_network(const char *fstype) {
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const char *x;
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x = startswith(fstype, "fuse.");
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if (x)
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fstype = x;
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if (nulstr_contains(filesystem_sets[FILESYSTEM_SET_NETWORK].value, fstype))
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return true;
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/* Filesystems not present in the internal database */
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return STR_IN_SET(fstype,
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"davfs",
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"glusterfs",
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"lustre",
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"sshfs");
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}
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bool fstype_needs_quota(const char *fstype) {
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/* 1. quotacheck needs to be run for some filesystems after they are mounted
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* if the filesystem was not unmounted cleanly.
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* 2. You may need to run quotaon to enable quota usage tracking and/or
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* enforcement.
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* ext2 - needs 1) and 2)
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* ext3 - needs 2) if configured using usrjquota/grpjquota mount options
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* ext4 - needs 1) if created without journal, needs 2) if created without QUOTA
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* filesystem feature
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* reiserfs - needs 2).
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* jfs - needs 2)
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* f2fs - needs 2) if configured using usrjquota/grpjquota/prjjquota mount options
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* xfs - nothing needed
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* gfs2 - nothing needed
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* ocfs2 - nothing needed
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* btrfs - nothing needed
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* for reference see filesystem and quota manpages */
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return STR_IN_SET(fstype,
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"ext2",
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"ext3",
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"ext4",
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"reiserfs",
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"jfs",
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"f2fs");
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}
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bool fstype_is_api_vfs(const char *fstype) {
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assert(fstype);
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const FilesystemSet *fs;
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FOREACH_ARGUMENT(fs,
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filesystem_sets + FILESYSTEM_SET_BASIC_API,
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filesystem_sets + FILESYSTEM_SET_AUXILIARY_API,
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filesystem_sets + FILESYSTEM_SET_PRIVILEGED_API,
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filesystem_sets + FILESYSTEM_SET_TEMPORARY)
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if (nulstr_contains(fs->value, fstype))
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return true;
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/* Filesystems not present in the internal database */
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return STR_IN_SET(fstype,
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"autofs",
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"cpuset");
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}
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bool fstype_is_blockdev_backed(const char *fstype) {
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const char *x;
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x = startswith(fstype, "fuse.");
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if (x)
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fstype = x;
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return !STR_IN_SET(fstype, "9p", "overlay") && !fstype_is_network(fstype) && !fstype_is_api_vfs(fstype);
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}
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bool fstype_is_ro(const char *fstype) {
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/* All Linux file systems that are necessarily read-only */
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return STR_IN_SET(fstype,
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"DM_verity_hash",
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"cramfs",
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"erofs",
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"iso9660",
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"squashfs");
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}
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bool fstype_can_discard(const char *fstype) {
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assert(fstype);
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/* Use a curated list as first check, to avoid calling fsopen() which might load kmods, which might
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* not be allowed in our MAC context. */
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if (STR_IN_SET(fstype, "btrfs", "f2fs", "ext4", "vfat", "xfs"))
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return true;
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/* On new kernels we can just ask the kernel */
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return mount_option_supported(fstype, "discard", NULL) > 0;
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}
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const char* fstype_norecovery_option(const char *fstype) {
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int r;
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assert(fstype);
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/* Use a curated list as first check, to avoid calling fsopen() which might load kmods, which might
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* not be allowed in our MAC context. */
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if (STR_IN_SET(fstype, "ext3", "ext4", "xfs"))
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return "norecovery";
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/* btrfs dropped support for the "norecovery" option in 6.8
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* (https://github.com/torvalds/linux/commit/a1912f712188291f9d7d434fba155461f1ebef66) and replaced
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* it with rescue=nologreplay, so we check for the new name first and fall back to checking for the
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* old name if the new name doesn't work. */
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if (streq(fstype, "btrfs")) {
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r = mount_option_supported(fstype, "rescue=nologreplay", NULL);
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if (r == -EAGAIN) {
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log_debug_errno(r, "Failed to check for btrfs 'rescue=nologreplay' option, assuming old kernel with 'norecovery': %m");
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return "norecovery";
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}
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if (r < 0)
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log_debug_errno(r, "Failed to check for btrfs 'rescue=nologreplay' option, assuming it is not supported: %m");
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if (r > 0)
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return "rescue=nologreplay";
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}
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/* On new kernels we can just ask the kernel */
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return mount_option_supported(fstype, "norecovery", NULL) > 0 ? "norecovery" : NULL;
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}
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bool fstype_can_fmask_dmask(const char *fstype) {
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assert(fstype);
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/* Use a curated list as first check, to avoid calling fsopen() which might load kmods, which might
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* not be allowed in our MAC context. If we don't know ourselves, on new kernels we can just ask the
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* kernel. */
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return streq(fstype, "vfat") || (mount_option_supported(fstype, "fmask", "0177") > 0 && mount_option_supported(fstype, "dmask", "0077") > 0);
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}
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|
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bool fstype_can_uid_gid(const char *fstype) {
|
||
/* All file systems that have a uid=/gid= mount option that fixates the owners of all files and
|
||
* directories, current and future. Note that this does *not* ask the kernel via
|
||
* mount_option_supported() here because the uid=/gid= setting of various file systems mean different
|
||
* things: some apply it only to the root dir inode, others to all inodes in the file system. Thus we
|
||
* maintain the curated list below. 😢 */
|
||
|
||
return STR_IN_SET(fstype,
|
||
"adfs",
|
||
"exfat",
|
||
"fat",
|
||
"hfs",
|
||
"hpfs",
|
||
"iso9660",
|
||
"msdos",
|
||
"ntfs",
|
||
"vfat");
|
||
}
|
||
|
||
int dev_is_devtmpfs(void) {
|
||
_cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
|
||
int mount_id, r;
|
||
char *e;
|
||
|
||
r = path_get_mnt_id("/dev", &mount_id);
|
||
if (r < 0)
|
||
return r;
|
||
|
||
r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo);
|
||
if (r == -ENOENT)
|
||
return proc_mounted() > 0 ? -ENOENT : -ENOSYS;
|
||
if (r < 0)
|
||
return r;
|
||
|
||
for (;;) {
|
||
_cleanup_free_ char *line = NULL;
|
||
int mid;
|
||
|
||
r = read_line(proc_self_mountinfo, LONG_LINE_MAX, &line);
|
||
if (r < 0)
|
||
return r;
|
||
if (r == 0)
|
||
break;
|
||
|
||
if (sscanf(line, "%i", &mid) != 1)
|
||
continue;
|
||
|
||
if (mid != mount_id)
|
||
continue;
|
||
|
||
e = strstrafter(line, " - ");
|
||
if (!e)
|
||
continue;
|
||
|
||
/* accept any name that starts with the currently expected type */
|
||
if (startswith(e, "devtmpfs"))
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
static int mount_fd(
|
||
const char *source,
|
||
int target_fd,
|
||
const char *filesystemtype,
|
||
unsigned long mountflags,
|
||
const void *data) {
|
||
|
||
assert(target_fd >= 0);
|
||
|
||
if (mount(source, FORMAT_PROC_FD_PATH(target_fd), filesystemtype, mountflags, data) < 0) {
|
||
if (errno != ENOENT)
|
||
return -errno;
|
||
|
||
/* ENOENT can mean two things: either that the source is missing, or that /proc/ isn't
|
||
* mounted. Check for the latter to generate better error messages. */
|
||
if (proc_mounted() == 0)
|
||
return -ENOSYS;
|
||
|
||
return -ENOENT;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
int mount_nofollow(
|
||
const char *source,
|
||
const char *target,
|
||
const char *filesystemtype,
|
||
unsigned long mountflags,
|
||
const void *data) {
|
||
|
||
_cleanup_close_ int fd = -EBADF;
|
||
|
||
assert(target);
|
||
|
||
/* In almost all cases we want to manipulate the mount table without following symlinks, hence
|
||
* mount_nofollow() is usually the way to go. The only exceptions are environments where /proc/ is
|
||
* not available yet, since we need /proc/self/fd/ for this logic to work. i.e. during the early
|
||
* initialization of namespacing/container stuff where /proc is not yet mounted (and maybe even the
|
||
* fs to mount) we can only use traditional mount() directly.
|
||
*
|
||
* Note that this disables following only for the final component of the target, i.e symlinks within
|
||
* the path of the target are honoured, as are symlinks in the source path everywhere. */
|
||
|
||
fd = open(target, O_PATH|O_CLOEXEC|O_NOFOLLOW);
|
||
if (fd < 0)
|
||
return -errno;
|
||
|
||
return mount_fd(source, fd, filesystemtype, mountflags, data);
|
||
}
|
||
|
||
const char* mount_propagation_flag_to_string(unsigned long flags) {
|
||
|
||
switch (flags & (MS_SHARED|MS_SLAVE|MS_PRIVATE)) {
|
||
case 0:
|
||
return "";
|
||
case MS_SHARED:
|
||
return "shared";
|
||
case MS_SLAVE:
|
||
return "slave";
|
||
case MS_PRIVATE:
|
||
return "private";
|
||
}
|
||
|
||
return NULL;
|
||
}
|
||
|
||
int mount_propagation_flag_from_string(const char *name, unsigned long *ret) {
|
||
|
||
if (isempty(name))
|
||
*ret = 0;
|
||
else if (streq(name, "shared"))
|
||
*ret = MS_SHARED;
|
||
else if (streq(name, "slave"))
|
||
*ret = MS_SLAVE;
|
||
else if (streq(name, "private"))
|
||
*ret = MS_PRIVATE;
|
||
else
|
||
return -EINVAL;
|
||
return 0;
|
||
}
|
||
|
||
bool mount_propagation_flag_is_valid(unsigned long flag) {
|
||
return IN_SET(flag, 0, MS_SHARED, MS_PRIVATE, MS_SLAVE);
|
||
}
|
||
|
||
bool mount_new_api_supported(void) {
|
||
static int cache = -1;
|
||
int r;
|
||
|
||
if (cache >= 0)
|
||
return cache;
|
||
|
||
/* This is the newest API among the ones we use, so use it as boundary */
|
||
r = RET_NERRNO(mount_setattr(-EBADF, NULL, 0, NULL, 0));
|
||
if (r == 0 || ERRNO_IS_NOT_SUPPORTED(r)) /* This should return an error if it is working properly */
|
||
return (cache = false);
|
||
|
||
return (cache = true);
|
||
}
|
||
|
||
int mount_option_supported(const char *fstype, const char *key, const char *value) {
|
||
_cleanup_close_ int fd = -EBADF;
|
||
int r;
|
||
|
||
/* Checks if the specified file system supports a mount option. Returns > 0 if it supports it, == 0 if
|
||
* it does not. Return -EAGAIN if we can't determine it. And any other error otherwise. */
|
||
|
||
assert(fstype);
|
||
assert(key);
|
||
|
||
fd = fsopen(fstype, FSOPEN_CLOEXEC);
|
||
if (fd < 0)
|
||
return log_debug_errno(errno, "Failed to open superblock context for '%s': %m", fstype);
|
||
|
||
/* Various file systems support fs context only in recent kernels (e.g. btrfs). For older kernels
|
||
* fsconfig() with FSCONFIG_SET_STRING/FSCONFIG_SET_FLAG never fail. Which sucks, because we want to
|
||
* use it for testing support, after all. Let's hence do a check if the file system got converted yet
|
||
* first. */
|
||
if (fsconfig(fd, FSCONFIG_SET_FD, "adefinitelynotexistingmountoption", NULL, fd) < 0) {
|
||
/* If FSCONFIG_SET_FD is not supported for the fs, then the file system was not converted to
|
||
* the new mount API yet. If it returns EINVAL the mount option doesn't exist, but the fstype
|
||
* is converted. */
|
||
if (errno == EOPNOTSUPP)
|
||
return -EAGAIN; /* fs not converted to new mount API → don't know */
|
||
if (errno != EINVAL)
|
||
return log_debug_errno(errno, "Failed to check if file system '%s' has been converted to new mount API: %m", fstype);
|
||
|
||
/* So FSCONFIG_SET_FD worked, but the option didn't exist (we got EINVAL), this means the fs
|
||
* is converted. Let's now ask the actual question we wonder about. */
|
||
} else
|
||
return log_debug_errno(SYNTHETIC_ERRNO(EAGAIN), "FSCONFIG_SET_FD worked unexpectedly for '%s', whoa!", fstype);
|
||
|
||
if (value)
|
||
r = fsconfig(fd, FSCONFIG_SET_STRING, key, value, 0);
|
||
else
|
||
r = fsconfig(fd, FSCONFIG_SET_FLAG, key, NULL, 0);
|
||
if (r < 0) {
|
||
if (errno == EINVAL)
|
||
return false; /* EINVAL means option not supported. */
|
||
|
||
return log_debug_errno(errno, "Failed to set '%s%s%s' on '%s' superblock context: %m",
|
||
key, value ? "=" : "", strempty(value), fstype);
|
||
}
|
||
|
||
return true; /* works! */
|
||
}
|
||
|
||
bool path_below_api_vfs(const char *p) {
|
||
assert(p);
|
||
|
||
/* API VFS are either directly mounted on any of these three paths, or below it. */
|
||
return PATH_STARTSWITH_SET(p, "/dev", "/sys", "/proc");
|
||
}
|