Add support for running multi-user in a chroot() environment.
How it works: - after successful execution of /etc/rc, check the value of "init.root" sysctl node, if it's different than "/", chroot() into its value and run /etc/rc inside the chroot(), - in single-user, return back to the original / file system. Allows running with / file system on e.g., cgd(4), vnd(4) or ccd(4) volumes. Idea first discussed with Matt Thomas, implemented by Jachym Holecek <freza (at) liberouter.org> with some nitpicks by me. Successfully used by me for almost a year with / on a cgd(4) volume (for more information about the setup check ftp://ftp.NetBSD.org/pub/NetBSD/misc/salo/init-chroot/ ).
This commit is contained in:
salo
parent
c8d2679980
commit
b0b7590bc7
@ -1,4 +1,4 @@
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# $NetBSD: Makefile,v 1.35 2005/01/13 03:21:59 lukem Exp $
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# $NetBSD: Makefile,v 1.36 2006/04/18 11:40:26 salo Exp $
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# @(#)Makefile 8.1 (Berkeley) 7/19/93
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PROG= init
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@ -10,7 +10,7 @@ CPPFLAGS+= -DMFS_DEV_IF_NO_CONSOLE -DSUPPORT_UTMP -DSUPPORT_UTMPX
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.ifdef SMALLPROG
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CPPFLAGS+= -DLETS_GET_SMALL
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.else
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CPPFLAGS+= -DALTSHELL -DSECURE
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CPPFLAGS+= -DALTSHELL -DSECURE -DCHROOT
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DPADD+= ${LIBCRYPT}
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LDADD+= -lcrypt
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.endif
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@ -1,4 +1,4 @@
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$NetBSD: NOTES,v 1.2 1995/03/18 14:56:29 cgd Exp $
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$NetBSD: NOTES,v 1.3 2006/04/18 11:40:26 salo Exp $
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POSIX and init:
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--------------
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@ -101,8 +101,13 @@ init is responsible for utmp and wtmp maintenance (ick)
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necessary states and state transitions (gleaned from the man page):
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1: single user shell (with password checking?); on exit, go to 2
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2: rc script: on exit 0, go to 3; on exit N (error), go to 1
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3: read ttys file: on completion, go to 4
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2: run rc script, on exit 0 check if init.root sysctl != "/", if it
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differs then fork + chroot into the value of init.root and run
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/etc/rc inside the chroot: on exit 0, go to 3; on exit N (error),
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go to 1 (applies also to /etc/rc when init.root == "/")
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3: read ttys file: on completion, go to 4. If we did chroot in
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state 2, we chroot after forking each getty to the same dir
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(init.root is not re-read)
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4: multi-user operation: on SIGTERM, go to 7; on SIGHUP, go to 5;
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on SIGTSTP, go to 6
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5: clean up mode (re-read ttys file, killing off controlling processes
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@ -1,4 +1,4 @@
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.\" $NetBSD: init.8,v 1.37 2005/11/13 18:39:53 elad Exp $
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.\" $NetBSD: init.8,v 1.38 2006/04/18 11:40:26 salo Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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@ -32,7 +32,7 @@
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.\"
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.\" @(#)init.8 8.6 (Berkeley) 5/26/95
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.\"
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.Dd November 13, 2005
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.Dd April 18, 2006
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.Dt INIT 8
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.Os
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.Sh NAME
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@ -78,11 +78,28 @@ exits with a non-zero (error) exit code, commence single user
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operation by giving the super-user a shell on the console by going
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to state 1 (single user).
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Otherwise, proceed to state 3.
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.Pp
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If value of the
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.Dq init.root
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sysctl node is not equal to
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.Pa /
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at this point, the
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.Pa /etc/rc
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process will be run inside a
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.Xr chroot 2
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indicated by sysctl with the same error handling as above.
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.It
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Set up ttys as specified in
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.Xr ttys 5 .
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See below for more information.
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On completion, continue to state 4.
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If we did chroot in state 2, each
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.Xr getty 8
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process will be run in the same
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.Xr chroot 2
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path as in 2 (that is, the value of
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.Dq init.root
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sysctl is not re-read).
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.It
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Multi-user operation.
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Depending upon the signal received, change state appropriately;
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@ -130,6 +147,26 @@ The password check is skipped if the
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is marked as
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.Dq secure .
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.Pp
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It should be noted that while
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.Nm
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has the ability to start multi-user operation inside a
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.Xr chroot 2
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environment, the
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.Nm
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process itself will always run in the
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.Dq original root directory .
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This also implies that single-user mode is always started in the original
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root, giving the possibility to create multi-user sessions in different
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root directories over time. The
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.Dq init.root
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sysctl node is fabricated by
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.Nm
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at startup and re-created any time it's found to be missing. Type of the
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node is string capable of holding full pathname, and is only accessible by
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the superuser (unless explicitly destroyed and re-created with different
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specification). The node becomes read-only after securelevel 1 has been
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reached.
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.Pp
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The kernel runs with four different levels of security.
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Any superuser process can raise the security level, but only
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.Nm
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@ -403,7 +440,8 @@ device driver because of a persistent device error condition.
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.Xr mfs 8 ,
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.Xr rc 8 ,
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.Xr reboot 8 ,
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.Xr shutdown 8
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.Xr shutdown 8 ,
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.Xr sysctl 8
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.Sh HISTORY
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A
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.Nm
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260
sbin/init/init.c
260
sbin/init/init.c
@ -1,4 +1,4 @@
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/* $NetBSD: init.c,v 1.72 2006/03/17 15:53:46 rumble Exp $ */
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/* $NetBSD: init.c,v 1.73 2006/04/18 11:40:26 salo Exp $ */
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/*-
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* Copyright (c) 1991, 1993
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@ -42,7 +42,7 @@ __COPYRIGHT("@(#) Copyright (c) 1991, 1993\n"
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#if 0
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static char sccsid[] = "@(#)init.c 8.2 (Berkeley) 4/28/95";
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#else
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__RCSID("$NetBSD: init.c,v 1.72 2006/03/17 15:53:46 rumble Exp $");
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__RCSID("$NetBSD: init.c,v 1.73 2006/04/18 11:40:26 salo Exp $");
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#endif
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#endif /* not lint */
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@ -135,12 +135,6 @@ state_func_t death(void);
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enum { AUTOBOOT, FASTBOOT } runcom_mode = AUTOBOOT;
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void transition(state_t);
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#ifndef LETS_GET_SMALL
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state_t requested_transition = runcom;
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#else /* LETS_GET_SMALL */
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state_t requested_transition = single_user;
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#endif /* LETS_GET_SMALL */
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void setctty(const char *);
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typedef struct init_session {
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@ -174,16 +168,31 @@ int getsecuritylevel(void);
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int setupargv(session_t *, struct ttyent *);
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int clang;
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#ifndef LETS_GET_SMALL
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void clear_session_logs(session_t *, int);
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#endif
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int start_session_db(void);
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void add_session(session_t *);
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void del_session(session_t *);
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session_t *find_session(pid_t);
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DB *session_db;
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int do_setttyent(void);
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#ifndef LETS_GET_SMALL
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state_t requested_transition = runcom;
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void clear_session_logs(session_t *, int);
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state_func_t runetcrc(int);
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#ifdef CHROOT
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int did_multiuser_chroot = 0;
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char rootdir[PATH_MAX];
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int shouldchroot(void);
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int createsysctlnode(void);
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#endif /* CHROOT */
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#else /* LETS_GET_SMALL */
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state_t requested_transition = single_user;
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#endif /* !LETS_GET_SMALL */
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#ifdef MFS_DEV_IF_NO_CONSOLE
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#define NINODE 1024
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@ -309,6 +318,11 @@ main(int argc, char **argv)
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(void)close(1);
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(void)close(2);
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#if !defined(LETS_GET_SMALL) && defined(CHROOT)
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/* Create "init.root" sysctl node. */
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createsysctlnode();
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#endif /* !LETS_GET_SMALL && CHROOT*/
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/*
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* Start the state machine.
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*/
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@ -392,6 +406,29 @@ warning(const char *message, ...)
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vsyslog(LOG_ALERT, message, ap);
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va_end(ap);
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closelog();
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#if 0
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/*
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* XXX: syslog seems to just plain not work in console-only
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* XXX: situation... that should be fixed. Let's leave this
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* XXX: note + code here in case someone gets in trouble and
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* XXX: wants to debug. -- Jachym Holecek <freza@liberouter.org>
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*/
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{
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char errbuf[1024];
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int fd, len;
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/* We can't do anything on errors, anyway... */
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fd = open(_PATH_CONSOLE, O_WRONLY);
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if (fd == -1)
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return ;
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/* %m will get lost... */
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len = vsnprintf(errbuf, sizeof(errbuf), message, ap);
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(void)write(fd, (void *)errbuf, len);
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(void)close(fd);
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}
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#endif
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}
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/*
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@ -566,6 +603,11 @@ single_user(void)
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char altshell[128];
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#endif /* ALTSHELL */
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#if !defined(LETS_GET_SMALL) && defined(CHROOT)
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/* Clear previous idea, just in case. */
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did_multiuser_chroot = 0;
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#endif /* !LETS_GET_SMALL && CHROOT */
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/*
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* If the kernel is in secure mode, downgrade it to insecure mode.
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*/
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@ -722,11 +764,10 @@ single_user(void)
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}
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#ifndef LETS_GET_SMALL
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/*
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* Run the system startup script.
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*/
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/* ARGSUSED */
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state_func_t
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runcom(void)
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runetcrc(int trychroot)
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{
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pid_t pid, wpid;
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int status;
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@ -745,11 +786,20 @@ runcom(void)
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argv[0] = "sh";
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argv[1] = _PATH_RUNCOM;
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argv[2] = runcom_mode == AUTOBOOT ? "autoboot" : 0;
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argv[2] = (runcom_mode == AUTOBOOT ? "autoboot" : 0);
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argv[3] = 0;
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(void)sigprocmask(SIG_SETMASK, &sa.sa_mask, NULL);
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#ifdef CHROOT
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if (trychroot)
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if (chroot(rootdir) != 0) {
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warning("failed to chroot to %s, error: %m",
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rootdir);
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_exit(1); /* force single user mode */
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}
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#endif /* CHROOT */
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(void)execv(INIT_BSHELL, __UNCONST(argv));
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stall("can't exec %s for %s: %m", INIT_BSHELL, _PATH_RUNCOM);
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_exit(1); /* force single user mode */
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@ -805,6 +855,43 @@ runcom(void)
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if (WEXITSTATUS(status))
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return (state_func_t)single_user;
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return (state_func_t) read_ttys;
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}
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/*
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* Run the system startup script.
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*/
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state_func_t
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runcom(void)
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{
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state_func_t next_step;
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/* Run /etc/rc and choose next state depending on the result. */
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next_step = runetcrc(0);
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if (next_step != (state_func_t) read_ttys)
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return (state_func_t) next_step;
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#ifdef CHROOT
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/*
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* If init.root sysctl does not point to "/", we'll chroot and run
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* The Real(tm) /etc/rc now. Global variable rootdir will tell us
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* where to go.
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*/
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if (shouldchroot()) {
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next_step = runetcrc(1);
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if (next_step != (state_func_t) read_ttys)
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return (state_func_t) next_step;
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did_multiuser_chroot = 1;
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} else {
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did_multiuser_chroot = 0;
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}
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#endif /* CHROOT */
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/*
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* Regardless of whether in chroot or not, we booted successfuly.
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* It's time to spawn gettys (ie. next_step's value at this point).
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*/
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runcom_mode = AUTOBOOT; /* the default */
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/* NB: should send a message to the session logger to avoid blocking. */
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#ifdef SUPPORT_UTMPX
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@ -1034,8 +1121,19 @@ read_ttys(void)
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free_session(sp);
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}
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sessions = NULL;
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if (start_session_db())
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if (start_session_db()) {
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warning("read_ttys: start_session_db failed, death\n");
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#ifdef CHROOT
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/* If /etc/rc ran in chroot, we want to kill any survivors. */
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if (did_multiuser_chroot)
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return (state_func_t)death;
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else
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#endif /* CHROOT */
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return (state_func_t)single_user;
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}
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do_setttyent();
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/*
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* Allocate a session entry for each active port.
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@ -1044,7 +1142,6 @@ read_ttys(void)
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while ((typ = getttyent()) != NULL)
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if ((snext = new_session(sp, ++session_index, typ)) != NULL)
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sp = snext;
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endttyent();
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return (state_func_t)multi_user;
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@ -1102,6 +1199,16 @@ start_getty(session_t *sp)
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if (pid)
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return pid;
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#ifdef CHROOT
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/* If /etc/rc did proceed inside chroot, we have to try as well. */
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if (did_multiuser_chroot)
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if (chroot(rootdir) != 0) {
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stall("can't chroot getty '%s' inside %s: %m",
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sp->se_getty_argv[0], rootdir);
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_exit(1);
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}
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#endif /* CHROOT */
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if (current_time > sp->se_started &&
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current_time - sp->se_started < GETTY_SPACING) {
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warning("getty repeating too quickly on port %s, sleeping",
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@ -1249,6 +1356,8 @@ clean_ttys(void)
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for (sp = sessions; sp; sp = sp->se_next)
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sp->se_flags &= ~SE_PRESENT;
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do_setttyent();
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devlen = sizeof(_PATH_DEV) - 1;
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while ((typ = getttyent()) != NULL) {
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++session_index;
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@ -1501,6 +1610,7 @@ mfs_dev(void)
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mfile[0].len ? "./MAKEDEV" : "/etc/MAKEDEV",
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"init", NULL);
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_exit(1);
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/* NOTREACHED */
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case -1:
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break;
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@ -1518,3 +1628,115 @@ mfs_dev(void)
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return (-1);
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}
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#endif
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int
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do_setttyent(void)
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{
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endttyent();
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#ifdef CHROOT
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if (did_multiuser_chroot) {
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char path[PATH_MAX];
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snprintf(path, sizeof(path), "%s/%s", rootdir, _PATH_TTYS);
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return setttyentpath(path);
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} else
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#endif /* CHROOT */
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return setttyent();
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}
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#if !defined(LETS_GET_SMALL) && defined(CHROOT)
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int
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createsysctlnode()
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{
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struct sysctlnode node;
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int mib[2];
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size_t len;
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/*
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* Create top-level dynamic sysctl node. Its child nodes will only
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* be readable by the superuser, since regular mortals should not
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* care ("Sssh, it's a secret!"). Additionally, both nodes become
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* read-only at securelevel 1.
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*/
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len = sizeof(struct sysctlnode);
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mib[0] = CTL_CREATE;
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memset(&node, 0, len);
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node.sysctl_flags = SYSCTL_VERSION | CTLFLAG_READWRITE |
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CTLFLAG_PRIVATE | CTLFLAG_READONLY1 | CTLTYPE_NODE;
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node.sysctl_num = CTL_CREATE;
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snprintf(node.sysctl_name, SYSCTL_NAMELEN, "init");
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if (sysctl(&mib[0], 1, &node, &len, &node, len) == -1) {
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warning("could not create init node, error = %d", errno);
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return (-1);
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}
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/*
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* Create second level dynamic node capable of holding pathname.
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* Provide "/" as the default value.
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*/
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len = sizeof(struct sysctlnode);
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mib[0] = node.sysctl_num;
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mib[1] = CTL_CREATE;
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memset(&node, 0, len);
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node.sysctl_flags = SYSCTL_VERSION | CTLFLAG_READWRITE |
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CTLFLAG_READONLY1 | CTLTYPE_STRING | CTLFLAG_OWNDATA;
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node.sysctl_size = _POSIX_PATH_MAX;
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node.sysctl_data = __UNCONST("/");
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node.sysctl_num = CTL_CREATE;
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snprintf(node.sysctl_name, SYSCTL_NAMELEN, "root");
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if (sysctl(&mib[0], 2, NULL, NULL, &node, len) == -1) {
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warning("could not create init.root node, error = %d", errno);
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return (-1);
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}
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return (0);
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}
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int
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shouldchroot()
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{
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struct sysctlnode node;
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size_t len, cnt;
|
||||
int mib;
|
||||
|
||||
len = sizeof(struct sysctlnode);
|
||||
|
||||
if (sysctlbyname("init.root", rootdir, &len, NULL, 0) == -1) {
|
||||
warning("could not read init.root, error = %d", errno);
|
||||
|
||||
/* Child killed our node. Recreate it. */
|
||||
if (errno == ENOENT) {
|
||||
/* Destroy whatever is left, recreate from scratch. */
|
||||
if (sysctlnametomib("init", &mib, &cnt) != -1) {
|
||||
memset(&node, 0, sizeof(node));
|
||||
node.sysctl_flags = SYSCTL_VERSION;
|
||||
node.sysctl_num = mib;
|
||||
mib = CTL_DESTROY;
|
||||
|
||||
(void)sysctl(&mib, 1, NULL, NULL, &node,
|
||||
sizeof(node));
|
||||
}
|
||||
|
||||
createsysctlnode();
|
||||
}
|
||||
|
||||
/* We certainly won't chroot. */
|
||||
return (0);
|
||||
}
|
||||
|
||||
if (rootdir[len] != '\0' || strlen(rootdir) != len - 1) {
|
||||
warning("init.root is not a string");
|
||||
return (0);
|
||||
}
|
||||
|
||||
if (strcmp(rootdir, "/") == 0)
|
||||
return (0);
|
||||
|
||||
return (1);
|
||||
}
|
||||
|
||||
#endif /* !LETS_GET_SMALL && CHROOT */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user