From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: util-linux-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:50467 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963Ab2LJMjm (ORCPT ); Mon, 10 Dec 2012 07:39:42 -0500 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id A22DEA500D for ; Mon, 10 Dec 2012 13:39:41 +0100 (CET) From: Werner Fink To: util-linux@vger.kernel.org Cc: Karel Zak , Werner Fink Subject: [PATCH 4/5] sulogin: mount temporary /dev and /proc if not found Date: Mon, 10 Dec 2012 13:27:10 +0100 Message-Id: <1355142431-8199-1-git-send-email-werner@suse.de> In-Reply-To: <20121207170118.GG603@rampage> References: <20121207170118.GG603@rampage> In-Reply-To: <20121207170118.GG603@rampage> References: <20121207170118.GG603@rampage> Sender: util-linux-owner@vger.kernel.org List-ID: On Fri, Dec 07, 2012 at 12:01:18PM -0500, Dave Reisner wrote: > > If you're in the initramfs, rootfs is tmpfs. Won't your statfs check > return a buffer which has f_type == TMPFS_MAGIC even if /dev is not > mounted? Indeed it could be a poroblem, therefore I've moved the stuff to lib/conosle.c and switch over to device comparission as you suggested. Also if /dev has been mounted by this code I'll also create missing nodes during scan of e.g. /proc/consoles On Fri, Dec 07, 2012 at 09:00:57AM +0100, Werner Fink wrote: > > This is very usefull if initrd can not loaded that is no /dev and no > /proc is found. Also if the /etc/shadow and /etc/passwd is copied into > the initrd the sulogin can be used in initrd even before /dev and/or /proc > are mounted. Signed-off-by: Werner Fink --- configure.ac | 10 +++++++++ lib/consoles.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 76 insertions(+) diff --git configure.ac configure.ac index 3be3715..631002f 100644 --- configure.ac +++ configure.ac @@ -1296,6 +1296,16 @@ if test "x$enable_use_tty_group" = xyes; then AC_DEFINE(USE_TTY_GROUP, 1, [Should wall and write be installed setgid tty?]) fi +AC_ARG_ENABLE([use-emergency-dev], + AS_HELP_STRING([--disable-use-emergency-dev], [do not use emergency mount of /dev and /proc for sulogin]), + [], enable_use_emergency_dev=yes +) +AM_CONDITIONAL(USE_EMERGENCY_DEV, test "x$enable_use_emergency_dev" = xyes) + +if test "x$enable_use_emergency_dev" = xyes; then + AC_DEFINE(USE_EMERGENCY_DEV, 1, [Should sulogin use a emergency mount of /dev and /proc?]) +fi + AC_ARG_ENABLE([makeinstall-chown], AS_HELP_STRING([--disable-makeinstall-chown], [do not do chown-like operations during "make install"]), [], enable_makeinstall_chown=yes diff --git lib/consoles.c lib/consoles.c index 38c8208..9f0617a 100644 --- lib/consoles.c +++ lib/consoles.c @@ -39,6 +39,16 @@ #include #include +#ifdef USE_EMERGENCY_DEV +# include +# include +# include +# include +# ifndef MNT_DETACH +# define MNT_DETACH 2 +# endif +#endif + #include "c.h" #include "canonicalize.h" #include "consoles.h" @@ -77,6 +87,57 @@ dbgprint(const char *mesg, ...) fputc('\n', stderr); } +#ifdef USE_EMERGENCY_DEV +/* + * Make C library standard calls such like ttyname(3) work + * even if the system does not show any of the standard + * directories. + */ + +static uint32_t mounts; +# define MNT_PROCFS 0x0001 +# define MNT_DEVTMPFS 0x0002 + +static __attribute__((__destructor__)) void putmounts(void) +{ + if (mounts & MNT_DEVTMPFS) + umount2("/dev", MNT_DETACH); + if (mounts & MNT_PROCFS) + umount2("/proc", MNT_DETACH); +} + +# define dovoid(f) if ((f)){} +static __attribute__((__constructor__)) void getmounts(void) +{ + struct stat rt; + struct stat xt; + if (mounts) { + mounts = 0; + return; + } + if (stat("/", &rt) != 0) { + warn("can not get file status of root file system\n"); + return; + } + if (stat("/proc", &xt) == 0 && rt.st_dev == xt.st_dev) { + if (mount("proc", "/proc", "proc", MS_RELATIME, NULL) == 0) + mounts |= MNT_PROCFS; + } + if (stat("/dev", &xt) == 0 && rt.st_dev == xt.st_dev) { + if (mount("devtmpfs", "/dev", "devtmpfs", MS_RELATIME, "mode=0755,nr_inodes=0") == 0) { + mounts |= MNT_DEVTMPFS; + (void)mknod("/dev/console", S_IFCHR|S_IRUSR|S_IWUSR, makedev(TTYAUX_MAJOR, 1)); + if (symlink("/proc/self/fd", "/dev/fd") == 0) { + dovoid(symlink("fd/0", "/dev/stdin")); + dovoid(symlink("fd/1", "/dev/stdout")); + dovoid(symlink("fd/2", "/dev/stderr")); + } + } + } +} +# undef dovoid +#endif + /* * Read and allocate one line from file, * the caller has to free the result @@ -182,6 +243,11 @@ char* scandev(DIR *dir, dev_t comparedev) continue; if ((size_t)snprintf(path, sizeof(path), "/dev/%s", dent->d_name) >= sizeof(path)) continue; +#ifdef USE_EMERGENCY_DEV + if (mounts & MNT_DEVTMPFS) + (void)mknod(path, S_IFCHR|S_IRUSR|S_IWUSR, comparedev); +#endif + name = canonicalize_path(path); break; } -- 1.7.10.4