| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <sys/mount.h> |
| |
| #include "alloc-util.h" |
| #include "blockdev-util.h" |
| #include "chase-symlinks.h" |
| #include "devnum-util.h" |
| #include "escape.h" |
| #include "main-func.h" |
| #include "mkdir.h" |
| #include "mount-util.h" |
| #include "mountpoint-util.h" |
| #include "path-util.h" |
| #include "string-util.h" |
| #include "volatile-util.h" |
| |
| static int make_volatile(const char *path) { |
| _cleanup_free_ char *old_usr = NULL; |
| int r; |
| |
| assert(path); |
| |
| r = chase_symlinks("/usr", path, CHASE_PREFIX_ROOT, &old_usr, NULL); |
| if (r < 0) |
| return log_error_errno(r, "/usr not available in old root: %m"); |
| |
| r = mkdir_p("/run/systemd/volatile-sysroot", 0700); |
| if (r < 0) |
| return log_error_errno(r, "Couldn't generate volatile sysroot directory: %m"); |
| |
| r = mount_nofollow_verbose(LOG_ERR, "tmpfs", "/run/systemd/volatile-sysroot", "tmpfs", MS_STRICTATIME, "mode=0755" TMPFS_LIMITS_ROOTFS); |
| if (r < 0) |
| goto finish_rmdir; |
| |
| if (mkdir("/run/systemd/volatile-sysroot/usr", 0755) < 0) { |
| r = log_error_errno(errno, "Failed to create /usr directory: %m"); |
| goto finish_umount; |
| } |
| |
| r = mount_nofollow_verbose(LOG_ERR, old_usr, "/run/systemd/volatile-sysroot/usr", NULL, MS_BIND|MS_REC, NULL); |
| if (r < 0) |
| goto finish_umount; |
| |
| r = bind_remount_recursive("/run/systemd/volatile-sysroot/usr", MS_RDONLY, MS_RDONLY, NULL); |
| if (r < 0) { |
| log_error_errno(r, "Failed to remount /usr read-only: %m"); |
| goto finish_umount; |
| } |
| |
| r = umount_recursive(path, 0); |
| if (r < 0) { |
| log_error_errno(r, "Failed to unmount %s: %m", path); |
| goto finish_umount; |
| } |
| |
| if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) |
| log_warning_errno(errno, "Failed to remount %s MS_SLAVE|MS_REC, ignoring: %m", path); |
| |
| r = mount_nofollow_verbose(LOG_ERR, "/run/systemd/volatile-sysroot", path, NULL, MS_MOVE, NULL); |
| |
| finish_umount: |
| (void) umount_recursive("/run/systemd/volatile-sysroot", 0); |
| |
| finish_rmdir: |
| (void) rmdir("/run/systemd/volatile-sysroot"); |
| |
| return r; |
| } |
| |
| static int make_overlay(const char *path) { |
| _cleanup_free_ char *escaped_path = NULL; |
| bool tmpfs_mounted = false; |
| const char *options = NULL; |
| int r; |
| |
| assert(path); |
| |
| r = mkdir_p("/run/systemd/overlay-sysroot", 0700); |
| if (r < 0) |
| return log_error_errno(r, "Couldn't create overlay sysroot directory: %m"); |
| |
| r = mount_nofollow_verbose(LOG_ERR, "tmpfs", "/run/systemd/overlay-sysroot", "tmpfs", MS_STRICTATIME, "mode=0755" TMPFS_LIMITS_ROOTFS); |
| if (r < 0) |
| goto finish; |
| |
| tmpfs_mounted = true; |
| |
| if (mkdir("/run/systemd/overlay-sysroot/upper", 0755) < 0) { |
| r = log_error_errno(errno, "Failed to create /run/systemd/overlay-sysroot/upper: %m"); |
| goto finish; |
| } |
| |
| if (mkdir("/run/systemd/overlay-sysroot/work", 0755) < 0) { |
| r = log_error_errno(errno, "Failed to create /run/systemd/overlay-sysroot/work: %m"); |
| goto finish; |
| } |
| |
| escaped_path = shell_escape(path, ",:"); |
| if (!escaped_path) { |
| r = log_oom(); |
| goto finish; |
| } |
| |
| options = strjoina("lowerdir=", escaped_path, ",upperdir=/run/systemd/overlay-sysroot/upper,workdir=/run/systemd/overlay-sysroot/work"); |
| r = mount_nofollow_verbose(LOG_ERR, "overlay", path, "overlay", 0, options); |
| |
| finish: |
| if (tmpfs_mounted) |
| (void) umount_verbose(LOG_ERR, "/run/systemd/overlay-sysroot", UMOUNT_NOFOLLOW); |
| |
| (void) rmdir("/run/systemd/overlay-sysroot"); |
| return r; |
| } |
| |
| static int run(int argc, char *argv[]) { |
| VolatileMode m = _VOLATILE_MODE_INVALID; |
| const char *path; |
| dev_t devt; |
| int r; |
| |
| log_setup(); |
| |
| if (argc > 3) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), |
| "Too many arguments. Expected directory and mode."); |
| |
| r = query_volatile_mode(&m); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine volatile mode from kernel command line: %m"); |
| if (r == 0 && argc >= 2) { |
| /* The kernel command line always wins. However if nothing was set there, the argument passed here wins instead. */ |
| m = volatile_mode_from_string(argv[1]); |
| if (m < 0) |
| return log_error_errno(m, "Couldn't parse volatile mode: %s", argv[1]); |
| } |
| |
| if (argc < 3) |
| path = "/sysroot"; |
| else { |
| path = argv[2]; |
| |
| if (isempty(path)) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), |
| "Directory name cannot be empty."); |
| if (!path_is_absolute(path)) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), |
| "Directory must be specified as absolute path."); |
| if (path_equal(path, "/")) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), |
| "Directory cannot be the root directory."); |
| } |
| |
| if (!IN_SET(m, VOLATILE_YES, VOLATILE_OVERLAY)) |
| return 0; |
| |
| r = path_is_mount_point(path, NULL, AT_SYMLINK_FOLLOW); |
| if (r < 0) |
| return log_error_errno(r, "Couldn't determine whether %s is a mount point: %m", path); |
| if (r == 0) |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "%s is not a mount point.", path); |
| |
| r = path_is_temporary_fs(path); |
| if (r < 0) |
| return log_error_errno(r, "Couldn't determine whether %s is a temporary file system: %m", path); |
| if (r > 0) { |
| log_info("%s already is a temporary file system.", path); |
| return 0; |
| } |
| |
| /* We are about to replace the root directory with something else. Later code might want to know what we |
| * replaced here, hence let's save that information as a symlink we can later use. (This is particularly |
| * relevant for the overlayfs case where we'll fully obstruct the view onto the underlying device, hence |
| * querying the backing device node from the file system directly is no longer possible. */ |
| r = get_block_device_harder(path, &devt); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine device major/minor of %s: %m", path); |
| else if (r > 0) { /* backed by block device */ |
| _cleanup_free_ char *dn = NULL; |
| |
| r = device_path_make_major_minor(S_IFBLK, devt, &dn); |
| if (r < 0) |
| return log_error_errno(r, "Failed to format device node path: %m"); |
| |
| if (symlink(dn, "/run/systemd/volatile-root") < 0) |
| log_warning_errno(errno, "Failed to create symlink /run/systemd/volatile-root: %m"); |
| } |
| |
| if (m == VOLATILE_YES) |
| return make_volatile(path); |
| else { |
| assert(m == VOLATILE_OVERLAY); |
| return make_overlay(path); |
| } |
| } |
| |
| DEFINE_MAIN_FUNCTION(run); |
