+/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
#include "escape.h"
#include "fd-util.h"
#include "fileio.h"
+#include "fs-util.h"
#include "hashmap.h"
#include "mount-util.h"
#include "parse-util.h"
#include "string-util.h"
#include "strv.h"
+/* This is the original MAX_HANDLE_SZ definition from the kernel, when the API was introduced. We use that in place of
+ * any more currently defined value to future-proof things: if the size is increased in the API headers, and our code
+ * is recompiled then it would cease working on old kernels, as those refuse any sizes larger than this value with
+ * EINVAL right-away. Hence, let's disconnect ourselves from any such API changes, and stick to the original definition
+ * from when it was introduced. We use it as a start value only anyway (see below), and hence should be able to deal
+ * with large file handles anyway. */
+#define ORIGINAL_MAX_HANDLE_SZ 128
+
+int name_to_handle_at_loop(
+ int fd,
+ const char *path,
+ struct file_handle **ret_handle,
+ int *ret_mnt_id,
+ int flags) {
+
+ _cleanup_free_ struct file_handle *h;
+ size_t n = ORIGINAL_MAX_HANDLE_SZ;
+
+ /* We need to invoke name_to_handle_at() in a loop, given that it might return EOVERFLOW when the specified
+ * buffer is too small. Note that in contrast to what the docs might suggest, MAX_HANDLE_SZ is only good as a
+ * start value, it is not an upper bound on the buffer size required.
+ *
+ * This improves on raw name_to_handle_at() also in one other regard: ret_handle and ret_mnt_id can be passed
+ * as NULL if there's no interest in either. */
+
+ h = malloc0(offsetof(struct file_handle, f_handle) + n);
+ if (!h)
+ return -ENOMEM;
+
+ h->handle_bytes = n;
+
+ for (;;) {
+ int mnt_id = -1;
+
+ if (name_to_handle_at(fd, path, h, &mnt_id, flags) >= 0) {
+
+ if (ret_handle) {
+ *ret_handle = h;
+ h = NULL;
+ }
+
+ if (ret_mnt_id)
+ *ret_mnt_id = mnt_id;
+
+ return 0;
+ }
+ if (errno != EOVERFLOW)
+ return -errno;
+
+ if (!ret_handle && ret_mnt_id && mnt_id >= 0) {
+
+ /* As it appears, name_to_handle_at() fills in mnt_id even when it returns EOVERFLOW when the
+ * buffer is too small, but that's undocumented. Hence, let's make use of this if it appears to
+ * be filled in, and the caller was interested in only the mount ID an nothing else. */
+
+ *ret_mnt_id = mnt_id;
+ return 0;
+ }
+
+ /* If name_to_handle_at() didn't increase the byte size, then this EOVERFLOW is caused by something
+ * else (apparently EOVERFLOW is returned for untriggered nfs4 mounts sometimes), not by the too small
+ * buffer. In that case propagate EOVERFLOW */
+ if (h->handle_bytes <= n)
+ return -EOVERFLOW;
+
+ /* The buffer was too small. Size the new buffer by what name_to_handle_at() returned. */
+ n = h->handle_bytes;
+ if (offsetof(struct file_handle, f_handle) + n < n) /* check for addition overflow */
+ return -EOVERFLOW;
+
+ free(h);
+ h = malloc0(offsetof(struct file_handle, f_handle) + n);
+ if (!h)
+ return -ENOMEM;
+
+ h->handle_bytes = n;
+ }
+}
+
static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) {
char path[strlen("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];
_cleanup_free_ char *fdinfo = NULL;
if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */
return -EOPNOTSUPP;
if (r < 0)
- return -errno;
+ return r;
p = startswith(fdinfo, "mnt_id:");
if (!p) {
}
int fd_is_mount_point(int fd, const char *filename, int flags) {
- union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT;
+ _cleanup_free_ struct file_handle *h = NULL, *h_parent = NULL;
int mount_id = -1, mount_id_parent = -1;
bool nosupp = false, check_st_dev = true;
struct stat a, b;
* subvolumes have different st_dev, even though they aren't
* real mounts of their own. */
- r = name_to_handle_at(fd, filename, &h.handle, &mount_id, flags);
- if (r < 0) {
- if (errno == ENOSYS)
- /* This kernel does not support name_to_handle_at()
- * fall back to simpler logic. */
+ r = name_to_handle_at_loop(fd, filename, &h, &mount_id, flags);
+ if (IN_SET(r, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL))
+ /* This kernel does not support name_to_handle_at() at all (ENOSYS), or the syscall was blocked
+ * (EACCES/EPERM; maybe through seccomp, because we are running inside of a container?), or the mount
+ * point is not triggered yet (EOVERFLOW, think nfs4), or some general name_to_handle_at() flakiness
+ * (EINVAL): fall back to simpler logic. */
+ goto fallback_fdinfo;
+ else if (r == -EOPNOTSUPP)
+ /* This kernel or file system does not support name_to_handle_at(), hence let's see if the upper fs
+ * supports it (in which case it is a mount point), otherwise fallback to the traditional stat()
+ * logic */
+ nosupp = true;
+ else if (r < 0)
+ return r;
+
+ r = name_to_handle_at_loop(fd, "", &h_parent, &mount_id_parent, AT_EMPTY_PATH);
+ if (r == -EOPNOTSUPP) {
+ if (nosupp)
+ /* Neither parent nor child do name_to_handle_at()? We have no choice but to fall back. */
goto fallback_fdinfo;
- else if (errno == EOPNOTSUPP)
- /* This kernel or file system does not support
- * name_to_handle_at(), hence let's see if the
- * upper fs supports it (in which case it is a
- * mount point), otherwise fallback to the
- * traditional stat() logic */
- nosupp = true;
else
- return -errno;
- }
-
- r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH);
- if (r < 0) {
- if (errno == EOPNOTSUPP) {
- if (nosupp)
- /* Neither parent nor child do name_to_handle_at()?
- We have no choice but to fall back. */
- goto fallback_fdinfo;
- else
- /* The parent can't do name_to_handle_at() but the
- * directory we are interested in can?
- * If so, it must be a mount point. */
- return 1;
- } else
- return -errno;
- }
+ /* The parent can't do name_to_handle_at() but the directory we are interested in can? If so,
+ * it must be a mount point. */
+ return 1;
+ } else if (r < 0)
+ return r;
/* The parent can do name_to_handle_at() but the
* directory we are interested in can't? If so, it
* assume this is the root directory, which is a mount
* point. */
- if (h.handle.handle_bytes == h_parent.handle.handle_bytes &&
- h.handle.handle_type == h_parent.handle.handle_type &&
- memcmp(h.handle.f_handle, h_parent.handle.f_handle, h.handle.handle_bytes) == 0)
+ if (h->handle_bytes == h_parent->handle_bytes &&
+ h->handle_type == h_parent->handle_type &&
+ memcmp(h->f_handle, h_parent->f_handle, h->handle_bytes) == 0)
return 1;
return mount_id != mount_id_parent;
fallback_fdinfo:
r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id);
- if (IN_SET(r, -EOPNOTSUPP, -EACCES))
+ if (IN_SET(r, -EOPNOTSUPP, -EACCES, -EPERM))
goto fallback_fstat;
if (r < 0)
return r;
}
/* flags can be AT_SYMLINK_FOLLOW or 0 */
-int path_is_mount_point(const char *t, int flags) {
- _cleanup_close_ int fd = -1;
+int path_is_mount_point(const char *t, const char *root, int flags) {
_cleanup_free_ char *canonical = NULL, *parent = NULL;
+ _cleanup_close_ int fd = -1;
+ int r;
assert(t);
+ assert((flags & ~AT_SYMLINK_FOLLOW) == 0);
if (path_equal(t, "/"))
return 1;
* /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
* look at needs to be /usr, not /. */
if (flags & AT_SYMLINK_FOLLOW) {
- canonical = canonicalize_file_name(t);
- if (!canonical)
- return -errno;
+ r = chase_symlinks(t, root, 0, &canonical);
+ if (r < 0)
+ return r;
t = canonical;
}
if (fd < 0)
return -errno;
- return fd_is_mount_point(fd, basename(t), flags);
+ return fd_is_mount_point(fd, last_path_component(t), flags);
+}
+
+int path_get_mnt_id(const char *path, int *ret) {
+ int r;
+
+ r = name_to_handle_at_loop(AT_FDCWD, path, NULL, ret, 0);
+ if (IN_SET(r, -EOPNOTSUPP, -ENOSYS, -EACCES, -EPERM, -EOVERFLOW, -EINVAL)) /* kernel/fs don't support this, or seccomp blocks access, or untriggered mount, or name_to_handle_at() is flaky */
+ return fd_fdinfo_mnt_id(AT_FDCWD, path, 0, ret);
+
+ return r;
}
int umount_recursive(const char *prefix, int flags) {
return 0;
}
-int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
+/* Use this function only if do you have direct access to /proc/self/mountinfo
+ * and need the caller to open it for you. This is the case when /proc is
+ * masked or not mounted. Otherwise, use bind_remount_recursive. */
+int bind_remount_recursive_with_mountinfo(const char *prefix, bool ro, char **blacklist, FILE *proc_self_mountinfo) {
_cleanup_set_free_free_ Set *done = NULL;
_cleanup_free_ char *cleaned = NULL;
int r;
+ assert(proc_self_mountinfo);
+
/* Recursively remount a directory (and all its submounts) read-only or read-write. If the directory is already
* mounted, we reuse the mount and simply mark it MS_BIND|MS_RDONLY (or remove the MS_RDONLY for read-write
* operation). If it isn't we first make it one. Afterwards we apply MS_BIND|MS_RDONLY (or remove MS_RDONLY) to
return -ENOMEM;
for (;;) {
- _cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
_cleanup_set_free_free_ Set *todo = NULL;
bool top_autofs = false;
char *x;
if (!todo)
return -ENOMEM;
- proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
- if (!proc_self_mountinfo)
- return -errno;
+ rewind(proc_self_mountinfo);
for (;;) {
_cleanup_free_ char *path = NULL, *p = NULL, *type = NULL;
while ((x = set_steal_first(todo))) {
r = set_consume(done, x);
- if (r == -EEXIST || r == 0)
+ if (IN_SET(r, 0, -EEXIST))
continue;
if (r < 0)
return r;
/* Deal with mount points that are obstructed by a later mount */
- r = path_is_mount_point(x, 0);
- if (r == -ENOENT || r == 0)
+ r = path_is_mount_point(x, NULL, 0);
+ if (IN_SET(r, 0, -ENOENT))
continue;
if (r < 0)
return r;
}
}
+int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
+ _cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
+
+ proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
+ if (!proc_self_mountinfo)
+ return -errno;
+
+ return bind_remount_recursive_with_mountinfo(prefix, ro, blacklist, proc_self_mountinfo);
+}
+
int mount_move_root(const char *path) {
assert(path);
}
bool fstype_is_network(const char *fstype) {
- static const char table[] =
- "afs\0"
- "cifs\0"
- "smbfs\0"
- "sshfs\0"
- "ncpfs\0"
- "ncp\0"
- "nfs\0"
- "nfs4\0"
- "gfs\0"
- "gfs2\0"
- "glusterfs\0"
- "pvfs2\0" /* OrangeFS */
- "ocfs2\0"
- "lustre\0"
- ;
-
const char *x;
x = startswith(fstype, "fuse.");
if (x)
fstype = x;
- return nulstr_contains(table, fstype);
+ return STR_IN_SET(fstype,
+ "afs",
+ "cifs",
+ "smbfs",
+ "sshfs",
+ "ncpfs",
+ "ncp",
+ "nfs",
+ "nfs4",
+ "gfs",
+ "gfs2",
+ "glusterfs",
+ "pvfs2", /* OrangeFS */
+ "ocfs2",
+ "lustre");
+}
+
+bool fstype_is_api_vfs(const char *fstype) {
+ return STR_IN_SET(fstype,
+ "autofs",
+ "bpf",
+ "cgroup",
+ "cgroup2",
+ "configfs",
+ "cpuset",
+ "debugfs",
+ "devpts",
+ "devtmpfs",
+ "efivarfs",
+ "fusectl",
+ "hugetlbfs",
+ "mqueue",
+ "proc",
+ "pstore",
+ "ramfs",
+ "securityfs",
+ "sysfs",
+ "tmpfs",
+ "tracefs");
+}
+
+bool fstype_is_ro(const char *fstype) {
+ /* All Linux file systems that are necessarily read-only */
+ return STR_IN_SET(fstype,
+ "DM_verity_hash",
+ "iso9660",
+ "squashfs");
+}
+
+bool fstype_can_discard(const char *fstype) {
+ return STR_IN_SET(fstype,
+ "btrfs",
+ "ext4",
+ "vfat",
+ "xfs");
}
int repeat_unmount(const char *path, int flags) {
FLAG(MS_I_VERSION),
FLAG(MS_STRICTATIME),
FLAG(MS_LAZYTIME),
- y, NULL);
+ y);
if (!x)
return NULL;
if (!y)
else if ((flags & MS_BIND) && !type)
log_debug("Bind-mounting %s on %s (%s \"%s\")...",
what, where, strnull(fl), strempty(options));
+ else if (flags & MS_MOVE)
+ log_debug("Moving mount %s → %s (%s \"%s\")...",
+ what, where, strnull(fl), strempty(options));
else
log_debug("Mounting %s on %s (%s \"%s\")...",
strna(type), where, strnull(fl), strempty(options));
return log_error_errno(errno, "Failed to unmount %s: %m", what);
return 0;
}
+
+const char *mount_propagation_flags_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_flags_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;
+}
projects / thirdparty / systemd.git / blobdiff