Systemd/src/basic/rm-rf.c

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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stddef.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <unistd.h>
#include "alloc-util.h"
#include "btrfs-util.h"
#include "cgroup-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "log.h"
#include "macro.h"
Split out part of mount-util.c into mountpoint-util.c The idea is that anything which is related to actually manipulating mounts is in mount-util.c, but functions for mountpoint introspection are moved to the new file. Anything which requires libmount must be in mount-util.c. This was supposed to be a preparation for further changes, with no functional difference, but it results in a significant change in linkage: $ ldd build/libnss_*.so.2 (before) build/libnss_myhostname.so.2: linux-vdso.so.1 (0x00007fff77bf5000) librt.so.1 => /lib64/librt.so.1 (0x00007f4bbb7b2000) libmount.so.1 => /lib64/libmount.so.1 (0x00007f4bbb755000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f4bbb734000) libc.so.6 => /lib64/libc.so.6 (0x00007f4bbb56e000) /lib64/ld-linux-x86-64.so.2 (0x00007f4bbb8c1000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007f4bbb51b000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007f4bbb512000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f4bbb4e3000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007f4bbb45e000) libdl.so.2 => /lib64/libdl.so.2 (0x00007f4bbb458000) build/libnss_mymachines.so.2: linux-vdso.so.1 (0x00007ffc19cc0000) librt.so.1 => /lib64/librt.so.1 (0x00007fdecb74b000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fdecb744000) libmount.so.1 => /lib64/libmount.so.1 (0x00007fdecb6e7000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fdecb6c6000) libc.so.6 => /lib64/libc.so.6 (0x00007fdecb500000) /lib64/ld-linux-x86-64.so.2 (0x00007fdecb8a9000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007fdecb4ad000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007fdecb4a2000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fdecb475000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007fdecb3f0000) libdl.so.2 => /lib64/libdl.so.2 (0x00007fdecb3ea000) build/libnss_resolve.so.2: linux-vdso.so.1 (0x00007ffe8ef8e000) librt.so.1 => /lib64/librt.so.1 (0x00007fcf314bd000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fcf314b6000) libmount.so.1 => /lib64/libmount.so.1 (0x00007fcf31459000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fcf31438000) libc.so.6 => /lib64/libc.so.6 (0x00007fcf31272000) /lib64/ld-linux-x86-64.so.2 (0x00007fcf31615000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007fcf3121f000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007fcf31214000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fcf311e7000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007fcf31162000) libdl.so.2 => /lib64/libdl.so.2 (0x00007fcf3115c000) build/libnss_systemd.so.2: linux-vdso.so.1 (0x00007ffda6d17000) librt.so.1 => /lib64/librt.so.1 (0x00007f610b83c000) libcap.so.2 => /lib64/libcap.so.2 (0x00007f610b835000) libmount.so.1 => /lib64/libmount.so.1 (0x00007f610b7d8000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f610b7b7000) libc.so.6 => /lib64/libc.so.6 (0x00007f610b5f1000) /lib64/ld-linux-x86-64.so.2 (0x00007f610b995000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007f610b59e000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007f610b593000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f610b566000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007f610b4e1000) libdl.so.2 => /lib64/libdl.so.2 (0x00007f610b4db000) (after) build/libnss_myhostname.so.2: linux-vdso.so.1 (0x00007fff0b5e2000) librt.so.1 => /lib64/librt.so.1 (0x00007fde0c328000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fde0c307000) libc.so.6 => /lib64/libc.so.6 (0x00007fde0c141000) /lib64/ld-linux-x86-64.so.2 (0x00007fde0c435000) build/libnss_mymachines.so.2: linux-vdso.so.1 (0x00007ffdc30a7000) librt.so.1 => /lib64/librt.so.1 (0x00007f06ecabb000) libcap.so.2 => /lib64/libcap.so.2 (0x00007f06ecab4000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f06eca93000) libc.so.6 => /lib64/libc.so.6 (0x00007f06ec8cd000) /lib64/ld-linux-x86-64.so.2 (0x00007f06ecc15000) build/libnss_resolve.so.2: linux-vdso.so.1 (0x00007ffe95747000) librt.so.1 => /lib64/librt.so.1 (0x00007fa56a80f000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fa56a808000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fa56a7e7000) libc.so.6 => /lib64/libc.so.6 (0x00007fa56a621000) /lib64/ld-linux-x86-64.so.2 (0x00007fa56a964000) build/libnss_systemd.so.2: linux-vdso.so.1 (0x00007ffe67b51000) librt.so.1 => /lib64/librt.so.1 (0x00007ffb32113000) libcap.so.2 => /lib64/libcap.so.2 (0x00007ffb3210c000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007ffb320eb000) libc.so.6 => /lib64/libc.so.6 (0x00007ffb31f25000) /lib64/ld-linux-x86-64.so.2 (0x00007ffb3226a000) I don't quite understand what is going on here, but let's not be too picky.
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#include "mountpoint-util.h"
#include "path-util.h"
#include "rm-rf.h"
#include "stat-util.h"
#include "string-util.h"
static bool is_physical_fs(const struct statfs *sfs) {
return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
}
int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
int ret = 0, r;
struct statfs sfs;
assert(fd >= 0);
/* This returns the first error we run into, but nevertheless
* tries to go on. This closes the passed fd. */
if (!(flags & REMOVE_PHYSICAL)) {
r = fstatfs(fd, &sfs);
if (r < 0) {
safe_close(fd);
return -errno;
}
if (is_physical_fs(&sfs)) {
/* We refuse to clean physical file systems with this call,
* unless explicitly requested. This is extra paranoia just
* to be sure we never ever remove non-state data. */
_cleanup_free_ char *path = NULL;
(void) fd_get_path(fd, &path);
log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
strna(path));
safe_close(fd);
return -EPERM;
}
}
d = fdopendir(fd);
if (!d) {
safe_close(fd);
return errno == ENOENT ? 0 : -errno;
}
FOREACH_DIRENT_ALL(de, d, return -errno) {
bool is_dir;
struct stat st;
if (dot_or_dot_dot(de->d_name))
continue;
if (de->d_type == DT_UNKNOWN ||
(de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
if (ret == 0 && errno != ENOENT)
ret = -errno;
continue;
}
is_dir = S_ISDIR(st.st_mode);
} else
is_dir = de->d_type == DT_DIR;
if (is_dir) {
int subdir_fd;
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/* if root_dev is set, remove subdirectories only if device is same */
if (root_dev && st.st_dev != root_dev->st_dev)
continue;
subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
if (subdir_fd < 0) {
if (ret == 0 && errno != ENOENT)
ret = -errno;
continue;
}
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/* Stop at mount points */
r = fd_is_mount_point(fd, de->d_name, 0);
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if (r < 0) {
if (ret == 0 && r != -ENOENT)
ret = r;
safe_close(subdir_fd);
continue;
}
if (r) {
safe_close(subdir_fd);
continue;
}
if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
/* This could be a subvolume, try to remove it */
r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
if (r < 0) {
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if (!IN_SET(r, -ENOTTY, -EINVAL)) {
if (ret == 0)
ret = r;
safe_close(subdir_fd);
continue;
}
/* ENOTTY, then it wasn't a
* btrfs subvolume, continue
* below. */
} else {
/* It was a subvolume, continue. */
safe_close(subdir_fd);
continue;
}
}
/* We pass REMOVE_PHYSICAL here, to avoid
* doing the fstatfs() to check the file
* system type again for each directory */
r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
if (r < 0 && ret == 0)
ret = r;
if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
if (ret == 0 && errno != ENOENT)
ret = -errno;
}
} else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
if (unlinkat(fd, de->d_name, 0) < 0) {
if (ret == 0 && errno != ENOENT)
ret = -errno;
}
}
}
return ret;
}
int rm_rf(const char *path, RemoveFlags flags) {
int fd, r;
struct statfs s;
assert(path);
/* For now, don't support dropping subvols when also only dropping directories, since we can't do
* this race-freely. */
if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
return -EINVAL;
/* We refuse to clean the root file system with this
* call. This is extra paranoia to never cause a really
* seriously broken system. */
if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW))
return log_error_errno(SYNTHETIC_ERRNO(EPERM),
"Attempted to remove entire root file system (\"%s\"), and we can't allow that.",
path);
if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
/* Try to remove as subvolume first */
r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
if (r >= 0)
return r;
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if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
return r;
/* Not btrfs or not a subvolume */
}
fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
if (fd < 0) {
if (!IN_SET(errno, ENOTDIR, ELOOP))
return -errno;
if (!(flags & REMOVE_PHYSICAL)) {
if (statfs(path, &s) < 0)
return -errno;
if (is_physical_fs(&s))
return log_error_errno(SYNTHETIC_ERRNO(EPERM),
"Attempted to remove files from a disk file system under \"%s\", refusing.",
path);
}
if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
if (unlink(path) < 0 && errno != ENOENT)
return -errno;
return 0;
}
r = rm_rf_children(fd, flags, NULL);
if (flags & REMOVE_ROOT) {
if (rmdir(path) < 0) {
if (r == 0 && errno != ENOENT)
r = -errno;
}
}
return r;
}