~ubuntu-branches/ubuntu/trusty/bash/trusty-security

Platform-Specific Configuration and Operation Notes

===================================================

1.  configure --without-gnu-malloc on:

	alpha running OSF/1, Linux, or NetBSD (malloc needs 8-byte alignment;

	bash malloc has 8-byte alignment now, but I have no alphas to test on)

	next running NeXT/OS; machines running Openstep

	all machines running SunOS YP code: SunOS4, SunOS5, HP/UX, if you

	have problems with username completion or tilde expansion for

	usernames found via YP/NIS

	linux (optional, but don't do it if you're using Doug Lea's malloc)

	QNX 4.2

	other OSF/1 machines (KSR/1, HP, IBM AIX/ESA)

	AIX

	sparc SVR4, SVR4.2 (ICL reference port)

	DG/UX

	Cray

	Haiku OS

	NetBSD/sparc (malloc needs 8-byte alignment; bash malloc has 8-byte

	alignment now, but I have no NetBSD machines to test on)

	BSD/OS 2.1, 3.x if you want to use loadable builtins

	Motorola m68k machines running System V.3.  There is a file descriptor

	leak caused by using the bash malloc because closedir(3) needs to read

	freed memory to find the file descriptor to close

2.  Configure using shlicc2 on BSD/OS 2.1 and BSD/OS 3.x to use loadable

    builtins

3.  Bash cannot be built in a directory separate from the source directory

    using configure --srcdir=... unless the version of `make' you're using

    does $VPATH handling right.  The script support/mkclone can be used to

    create a `build tree' using symlinks to get around this.

4.  I've had reports that username completion (as well as tilde expansion

    and \u prompt expansion) does not work on IRIX 5.3 when linking with

    -lnsl.  This is only a problem when you're running NIS, since

    apparently -lnsl supports only /etc/passwd and not the NIS functions

    for retrieving usernames and passwords.  Editing the Makefile after

    configure runs and removing the `-lnsl' from the assignment to `LIBS'

    fixes the problem.

5.  There is a problem with the `makewhatis' script in older (pre-7.0)

    versions of Red Hat Linux.  Running `makewhatis' with bash-2.0 or

    later versions results in error messages like this:

    /usr/sbin/makewhatis: cd: manpath: No such file or directory

    /usr/sbin/makewhatis: manpath/whatis: No such file or directory

    chmod: manpath/whatis: No such file or directory

    /usr/sbin/makewhatis: cd: catpath: No such file or directory

    /usr/sbin/makewhatis: catpath/whatis: No such file or directory

    chmod: catpath/whatis: No such file or directory

    The problem is with `makewhatis'.  Red Hat (and possibly other

    Linux distributors) uses a construct like this in the code:

        eval path=$"$pages"path

    to do indirect variable expansion.  This `happened to work' in

    bash-1.14 and previous versions, but that was more an accident

    of implementation than anything else -- it was never supported

    and certainly is not portable.

    Bash-2.0 has a new feature that gives a new meaning to $"...".

    This is explained more completely in item 1 in the COMPAT file.

    The three lines in the `makewhatis' script that need to be changed

    look like this:

             eval $topath=$"$topath":$name

    [...]

       eval path=$"$pages"path

    [...]

    eval path=$"$pages"path

    The portable way to write this code is

             eval $topath="\$$topath":$name

       eval path="\$$pages"path

    eval path="\$$pages"path

    You could also experiment with another new bash feature: ${!var}.

    This does indirect variable expansion, making the use of eval

    unnecessary.

6.  There is a problem with syslogd on many Linux distributions (Red Hat

    and Slackware are two that I have received reports about).  syslogd

    sends a SIGINT to its parent process, which is waiting for the daemon

    to finish its initialization.  The parent process then dies due to

    the SIGINT, and bash reports it, causing unexpected console output

    while the system is booting that looks something like

	starting daemons: syslogd/etc/rc.d/rc.M: line 29: 38 Interrupt ${NET}/syslogd

    Bash-2.0 reports events such as processes dying in scripts due to

    signals when the standard output is a tty.  Bash-1.14.x and previous

    versions did not report such events.

    This should probably be reported as a bug to whatever Linux distributor

    people see the problem on.  In my opinion, syslogd should be changed to

    use some other method of communication, or the wrapper function (which

    appeared to be `daemon' when I looked at it some time ago) or script

    (which appeared to be `syslog') should catch SIGINT, since it's an

    expected event, and exit cleanly.

7.  Several people have reported that `dip' (a program for SLIP/PPP

    on Linux) does not work with bash-2.0 installed as /bin/sh.

    I don't run any Linux boxes myself, and do not have the dip

    code handy to look at, but the `problem' with bash-2.0, as

    it has been related to me, is that bash requires the `-p'

    option to be supplied at invocation if it is to run setuid

    or setgid. 

    This means, among other things, that setuid or setgid programs

    which call system(3) (a horrendously bad practice in any case)

    relinquish their setuid/setgid status in the child that's forked

    to execute /bin/sh. 

    The following is an *unofficial* patch to bash-2.0 that causes it

    to not require `-p' to run setuid or setgid if invoked as `sh'.

    It has been reported to work on Linux.  It will make your system

    vulnerable to bogus system(3) calls in setuid executables.

--- ../bash-2.0.orig/shell.c    Wed Dec 18 14:16:30 1996

+++ shell.c     Fri Mar  7 13:12:03 1997

@@ -347,7 +347,7 @@

   if (posixly_correct)

     posix_initialize (posixly_correct);

-  if (running_setuid && privileged_mode == 0)

+  if (running_setuid && privileged_mode == 0 && act_like_sh == 0)

     disable_priv_mode ();

   /* Need to get the argument to a -c option processed in the

8.  Some people have asked about binding all of the keys in a PC-keyboard-

    style numeric keypad to readline functions.  Here's something I

    received from the gnu-win32 list that may help.  Insert the following

    lines into ~/.inputrc:

# home key

"\e[1~":beginning-of-line

# insert key

"\e[2~":kill-whole-line

# del key

"\e[3~":delete-char

# end key

"\e[4~":end-of-line

# pgup key

"\e[5~":history-search-forward

# pgdn key

"\e[6~":history-search-backward

9.  Hints for building under Minix 2.0 (Contributed by Terry R. McConnell,

    <tmc@barnyard.syr.edu>)

   The version of /bin/sh distributed with Minix is not up to the job of

   running the configure script. The easiest solution is to swap /bin/sh

   with /usr/bin/ash. Then use chmem(1) to increase the memory allocated

   to /bin/sh. The following settings are known to work:

   text         data     bss   stack  memory

   63552  9440          3304   65536  141832  /bin/sh

   If you have problems with make or yacc it may be worthwhile first to

   install the GNU versions of these utilities before attempting to build

   bash. (As of this writing, all of these utilities are available for the

   i386 as pre-built binaries via anonymous ftp at math.syr.edu in the

   pub/mcconnell/minix directory. Note that the GNU version of yacc is called

   bison.)

   Unless you want to see lots of warnings about old-style declarations,

   do LOCAL_CFLAGS=-wo; export LOCAL_CFLAGS before running configure.

   (These warnings are harmless, but annoying.)

   configure will insist that you supply a host type. For example, do

   ./configure --host=i386-pc-minix.

   Minix does not support the system calls required for a proper 

   implementation of ulimit().  The `ulimit' builtin will not be available.

   Configure will fail to notice that many things like uid_t are indeed

   typedef'd in <sys/types.h>, because it uses egrep for this purpose

   and minix has no egrep. You could try making a link /usr/bin/egrep -->

   /usr/bin/grep. Better is to install the GNU version of grep in

   /usr/local/bin and make the link /usr/local/bin/egrep -->/usr/local/bin/grep.

   (These must be hard links, of course, since Minix does not support

   symbolic links.)

   You will see many warnings of the form:

   warning: unknown s_type: 98

   I have no idea what this means, but it doesn't seem to matter.

10. If you do not have /usr/ccs/bin in your PATH when building on SunOS 5.x

    (Solaris 2), the configure script will be unable to find `ar' and

    `ranlib' (of course, ranlib is unnecessary).  Make sure your $PATH

    includes /usr/ccs/bin on SunOS 5.x.  This generally manifests itself

    with libraries not being built and make reporting errors like

    `cr: not found' when library construction is attempted.

11. Building a statically-linked bash on Solaris 2.5.x, 2.6, 7, or 8 is

    complicated.

    It's not possible to build a completely statically-linked binary, since

    part of the C library depends on dynamic linking.  The following recipe

    assumes that you're using gcc and the Solaris ld (/usr/ccs/bin/ld) on

    Solaris 2.5.x or 2.6:

	configure --enable-static-link

	make STATIC_LD= LOCAL_LIBS='-Wl,-B,dynamic -ldl -Wl,-B,static'

    This should result in a bash binary that depends only on libdl.so:

	thor(2)$ ldd bash

	        libdl.so.1 =>    /usr/lib/libdl.so.1

    If you're using the Sun C Compiler (Sun WorkShop C Compiler version

    4.2 was what I used), you should be able to get away with using

	configure --enable-static-link

	make STATIC_LD=  LOCAL_LIBS='-B dynamic -ldl -B static'

    If you want to completely remove any dependence on /usr, perhaps

    to put a copy of bash in /sbin and have it available when /usr is

    not mounted, force the build process to use the shared dl.so library

    in /etc/lib.

    For gcc, this would be something like

	configure --enable-static-link

	make STATIC_LD= LOCAL_LIBS='-Wl,-B,dynamic -Wl,-R/etc/lib -ldl -Wl,-B,static'

    For Sun's WS4.2 cc

	configure --enable-static-link

	make STATIC_LD=  LOCAL_LIBS='-B dynamic -R/etc/lib -ldl -B static'

    seems to work, at least on Solaris 2.5.1:

	thor(2)$ ldd bash

	        libdl.so.1 =>    /etc/lib/libdl.so.1

    On Solaris 7 (Solaris 8, using the version of gcc on the free software

    CD-ROM), the following recipe appears to work for gcc:

	configure --enable-static-link

	make STATIC_LD='-Wl,-Bstatic' LOCAL_LIBS='-Wl,-Bdynamic -Wl,-R/etc/lib -ldl -Wl,-Bstatic'

	thor.ins.cwru.edu(2)$ ldd bash

	        libdl.so.1 =>    /etc/lib/libdl.so.1

    Make the analogous changes if you are running Sun's C Compiler.

    I have received word that adding -L/etc/lib (or the equivalent

    -Wl,-L/etc/lib) might also be necessary, in addition to the -R/etc/lib.

    On later versions of Solaris, it may be necessary to add -lnsl before

    -ldl; statically-linked versions of bash using libnsl are not guaranteed

    to work correctly on future versions of Solaris.

12. Configuring bash to build it in a cross environment.  Currently only

    two native versions can be compiled this way, cygwin32 and x86 BeOS.

    For BeOS, you would configure it like this:

	export RANLIB=i586-beos-ranlib

	export AR=i586-beos-ar

	export CC=i586-beos-gcc

	configure i586-beos

    Similarly for cygwin32.

13. Bash-2.05 has reverted to the bash-2.03 behavior of honoring the current

    locale setting when processing ranges within pattern matching bracket

    expressions ([A-Z]).  This is what POSIX.2 and SUSv2 specify.

    The behavior of the matcher in bash-2.05 depends on the current LC_COLLATE

    setting.  Setting this variable to `C' or `POSIX' will result in the

    traditional behavior ([A-Z] matches all uppercase ASCII characters).

    Many other locales, including the en_US locale (the default on many US

    versions of Linux) collate the upper and lower case letters like this:

	AaBb...Zz

    which means that [A-Z] matches every letter except `z'.

    The portable way to specify upper case letters is [:upper:] instead of

    A-Z; lower case may be specified as [:lower:] instead of a-z.

    Look at the manual pages for setlocale(3), strcoll(3), and, if it is

    present, locale(1).  If you have locale(1), you can use it to find

    your current locale information even if you do not have any of the

    LC_ variables set.

    My advice is to put

        export LC_COLLATE=C

    into /etc/profile and inspect any shell scripts run from cron for

    constructs like [A-Z].  This will prevent things like

	rm [A-Z]*

    from removing every file in the current directory except those beginning

    with `z' and still allow individual users to change the collation order.

    Users may put the above command into their own profiles as well, of course.

14. Building on Interix (nee OpenNT), which Microsoft bought from Softway

    Systems and has seemingly abandoned (thanks to Kevin Moore for this item).

	1.  cp cross-build/opennt.cache config.cache

	2.  If desired, edit pathnames.h to set the values of SYS_PROFILE and

	    DEFAULT_HOSTS_FILE appropriately.

	3.  export CONFIG_SHELL=$INTERIX_ROOT/bin/sh

	4.  ./configure --prefix=$INTERIX_ROOT/usr/local (or wherever you

	    want it).

	5. make; make install; enjoy

15.  Configure with `CC=xlc' if you don't have gcc on AIX 4.2 and later

     versions.  `xlc' running in `cc' mode has trouble compiling error.c.

16.  Configure --disable-multibyte on NetBSD versions (1.4 through at least

     1.6.1) that include wctype.h but do not define wctype_t.

17.  Do NOT use bison-1.75.  It builds a non-working parser.  The most

     obvious effect is that constructs like "for i; do echo $i; done" don't

     loop over the positional parameters.

18.  I have received reports that using -O2 with the MIPSpro results in a

     binary that fails in strange ways.  Using -O1 seems to work.

19.  There is special handling to ensure the shell links against static

     versions of the included readline and history libraries on Mac OS X;

     Apple ships inadequate dynamic libreadline and libhistory "replacements"

     as standard libraries.

20.  If you're on a system like SGI Irix, and you get an error about not

     being able to refer to a dynamic symbol

     (ld: non-dynamic relocations refer to dynamic symbol PC), add

     -DNEED_EXTERN_PC to the LOCAL_CFLAGS variable in lib/readline/Makefile.in

     and rebuild.