The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=4c9f648852629d757165796bb3cd97bb84a0e483
commit 4c9f648852629d757165796bb3cd97bb84a0e483 Author: Konstantin Belousov <[email protected]> AuthorDate: 2026-07-10 19:02:54 +0000 Commit: Konstantin Belousov <[email protected]> CommitDate: 2026-07-14 15:43:45 +0000 init(8): extract reroot transient code into reroot_seed Since init become dynamically linked, reroot appeared to be broken because init copies itself into a transient tmpfs mount to continue controlling execution right after the reboot(REROOT) syscall. Because the binary is dynamically linked, it cannot be properly executed. Provide a minimal static binary 'reroot_seed' embedded into the init as byte stream, which performs what the 'init -r' did, namely, the second phase reroot. For the static build of init as part of the /rescue crunch, keep the inline reroot code. Reported and tested by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D58164 --- sbin/Makefile | 2 + sbin/init/Makefile | 9 +++- sbin/init/init.c | 91 +++++++++++++++++++++++++++------- sbin/init/reroot_seed.embed.s | 4 ++ sbin/reroot_seed/Makefile | 6 +++ sbin/reroot_seed/reroot_seed.c | 109 +++++++++++++++++++++++++++++++++++++++++ 6 files changed, 203 insertions(+), 18 deletions(-) diff --git a/sbin/Makefile b/sbin/Makefile index ef953e80ba1e..f936a9646fa9 100644 --- a/sbin/Makefile +++ b/sbin/Makefile @@ -25,6 +25,8 @@ SUBDIR=adjkerntz \ ggate \ growfs \ ifconfig \ + reroot_seed \ + .WAIT \ init \ kldconfig \ kldload \ diff --git a/sbin/init/Makefile b/sbin/init/Makefile index 342df4596a72..1e319f1bb828 100644 --- a/sbin/init/Makefile +++ b/sbin/init/Makefile @@ -2,9 +2,16 @@ CONFGROUPS= CONFTTYS PACKAGE=runtime PROG= init MAN= init.8 +SRCS= init.c PRECIOUSPROG= INSTALLFLAGS=-b -B.bak -CFLAGS+=-DDEBUGSHELL -DSECURE -DLOGIN_CAP -DCOMPAT_SYSV_INIT +CFLAGS.init.c+=-DDEBUGSHELL -DSECURE -DLOGIN_CAP -DCOMPAT_SYSV_INIT +.ifdef RESCUE +CFLAGS.init.c+=-DRESCUE +.else +SRCS+= reroot_seed.embed.s +ACFLAGS.reroot_seed.embed.s+=-I${OBJTOP}/sbin/reroot_seed +.endif LIBADD= util crypt CONFTTYSNAME= ttys diff --git a/sbin/init/init.c b/sbin/init/init.c index db680c7f73bd..1e07ca1d09c0 100644 --- a/sbin/init/init.c +++ b/sbin/init/init.c @@ -116,7 +116,9 @@ static state_func_t catatonia(void); static state_func_t death(void); static state_func_t death_single(void); static state_func_t reroot(void); +#ifdef RESCUE static state_func_t reroot_phase_two(void); +#endif static state_func_t run_script(const char *); @@ -269,7 +271,11 @@ invalid: * This code assumes that we always get arguments through flags, * never through bits set in some random machine register. */ - while ((c = getopt(argc, argv, "dsfr")) != -1) + while ((c = getopt(argc, argv, "dsf" +#ifdef RESCUE + "r" +#endif + )) != -1) switch (c) { case 'd': devfs = true; @@ -280,9 +286,11 @@ invalid: case 'f': runcom_mode = FASTBOOT; break; +#ifdef RESCUE case 'r': initial_transition = reroot_phase_two; break; +#endif default: warning("unrecognized flag '-%c'", c); break; @@ -388,7 +396,10 @@ invalid: free(s); } - if (initial_transition != reroot_phase_two) { +#ifdef RESCUE + if (initial_transition != reroot_phase_two) +#endif + { /* * Unmount reroot leftovers. This runs after init(8) * gets reexecuted after reroot_phase_two() is done. @@ -628,6 +639,7 @@ write_stderr(const char *message) write(STDERR_FILENO, message, strlen(message)); } +#ifdef RESCUE static int read_file(const char *path, void **bufp, size_t *bufsizep) { @@ -678,6 +690,7 @@ read_file(const char *path, void **bufp, size_t *bufsizep) return (0); } +#endif /* RESCUE */ static int create_file(const char *path, const void *buf, size_t bufsize) @@ -738,16 +751,14 @@ mount_tmpfs(const char *fspath) return (0); } +#ifndef RESCUE +extern char reroot_seed_start[], reroot_seed_end[]; + static state_func_t reroot(void) { - void *buf; - size_t bufsize; int error; - buf = NULL; - bufsize = 0; - revoke_ttys(); runshutdown(); @@ -762,32 +773,27 @@ reroot(void) goto out; } - /* - * Copy the init binary into tmpfs, so that we can unmount - * the old rootfs without committing suicide. - */ - error = read_file(init_path_argv0, &buf, &bufsize); - if (error != 0) - goto out; error = mount_tmpfs(_PATH_REROOT); if (error != 0) goto out; - error = create_file(_PATH_REROOT_INIT, buf, bufsize); + error = create_file(_PATH_REROOT_INIT, reroot_seed_start, + reroot_seed_end - reroot_seed_start); if (error != 0) goto out; /* * Execute the temporary init. */ - execl(_PATH_REROOT_INIT, _PATH_REROOT_INIT, "-r", NULL); + execl(_PATH_REROOT_INIT, _PATH_REROOT_INIT, NULL); emergency("cannot exec %s: %m", _PATH_REROOT_INIT); out: emergency("reroot failed; going to single user mode"); - free(buf); return (state_func_t) single_user; } +#else /* !RESCUE */ + static state_func_t reroot_phase_two(void) { @@ -839,6 +845,57 @@ out: return (state_func_t) single_user; } +static state_func_t +reroot(void) +{ + void *buf; + size_t bufsize; + int error; + + buf = NULL; + bufsize = 0; + + revoke_ttys(); + runshutdown(); + + /* + * Make sure nobody can interfere with our scheme. + * Ignore ESRCH, which can apparently happen when + * there are no processes to kill. + */ + error = kill(-1, SIGKILL); + if (error != 0 && errno != ESRCH) { + emergency("kill(2) failed: %m"); + goto out; + } + + /* + * Copy the init binary into tmpfs, so that we can unmount + * the old rootfs without committing suicide. + */ + error = read_file(init_path_argv0, &buf, &bufsize); + if (error != 0) + goto out; + error = mount_tmpfs(_PATH_REROOT); + if (error != 0) + goto out; + error = create_file(_PATH_REROOT_INIT, buf, bufsize); + if (error != 0) + goto out; + + /* + * Execute the temporary init. + */ + execl(_PATH_REROOT_INIT, _PATH_REROOT_INIT, "-r", NULL); + emergency("cannot exec %s: %m", _PATH_REROOT_INIT); + +out: + emergency("reroot failed; going to single user mode"); + return (state_func_t) single_user; +} + +#endif /* !RESCUE */ + /* * Bring the system up single user. */ diff --git a/sbin/init/reroot_seed.embed.s b/sbin/init/reroot_seed.embed.s new file mode 100644 index 000000000000..5871c41f06d0 --- /dev/null +++ b/sbin/init/reroot_seed.embed.s @@ -0,0 +1,4 @@ + .globl reroot_seed_start, reroot_seed_end +reroot_seed_start: + .incbin "reroot_seed" +reroot_seed_end: diff --git a/sbin/reroot_seed/Makefile b/sbin/reroot_seed/Makefile new file mode 100644 index 000000000000..584775aa287f --- /dev/null +++ b/sbin/reroot_seed/Makefile @@ -0,0 +1,6 @@ +PROG= reroot_seed +MAN= +NO_SHARED= YES +INTERNALPROG= YES + +.include <bsd.prog.mk> diff --git a/sbin/reroot_seed/reroot_seed.c b/sbin/reroot_seed/reroot_seed.c new file mode 100644 index 000000000000..9ba8516ba70f --- /dev/null +++ b/sbin/reroot_seed/reroot_seed.c @@ -0,0 +1,109 @@ +/*- + * SPDX-License-Identifier: BSD-3-Clause + * + * Copyright (c) 1991, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Donn Seeley at Berkeley Software Design, Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/param.h> +#include <sys/mount.h> +#include <sys/reboot.h> +#include <sys/sysctl.h> + +#include <err.h> +#include <kenv.h> +#include <paths.h> +#include <stdarg.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <unistd.h> + +static void emergency(const char *, ...) __printflike(1, 2); + +static void +emergency(const char *message, ...) +{ + va_list ap; + va_start(ap, message); + + vsyslog(LOG_EMERG, message, ap); + va_end(ap); +} + +int +main(void) +{ + char init_path[PATH_MAX], *path, *path_component; + size_t init_path_len; + int nbytes, error; + + openlog("init", LOG_CONS, LOG_AUTH); + + /* + * Ask the kernel to mount the new rootfs. + */ + error = reboot(RB_REROOT); + if (error != 0) { + emergency("RB_REBOOT failed: %m"); + _exit(1); + } + + /* + * Figure out where the destination init(8) binary is. Note that + * the path could be different than what we've started with. Use + * the value from kenv, if set, or the one from sysctl otherwise. + * The latter defaults to a hardcoded value, but can be overridden + * by a build time option. + */ + nbytes = kenv(KENV_GET, "init_path", init_path, sizeof(init_path)); + if (nbytes <= 0) { + init_path_len = sizeof(init_path); + error = sysctlbyname("kern.init_path", + init_path, &init_path_len, NULL, 0); + if (error != 0) { + emergency("failed to retrieve kern.init_path: %m"); + _exit(1); + } + } + + /* + * Repeat the init search logic from sys/kern/init_path.c + */ + path_component = init_path; + while ((path = strsep(&path_component, ":")) != NULL) { + /* + * Execute init(8) from the new rootfs. + */ + execl(path, path, NULL); + } + emergency("cannot exec init from %s: %m", init_path); + _exit(1); +}
