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Diffstat (limited to 'smrsh.8')
| -rw-r--r-- | smrsh.8 | 104 |
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@@ -0,0 +1,104 @@ +.\" Copyright (c) 1993 Eric P. Allman +.\" Copyright (c) 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" 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. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. 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. +.\" +.\" @(#)smrsh.8 8.2 (Berkeley) 1/9/96 +.\" +.TH SMRSH 8 11/02/93 +.SH NAME +smrsh \- restricted shell for sendmail +.SH SYNOPSIS +.B smrsh +.B \-c +command +.SH DESCRIPTION +The +.I smrsh +program is intended as a replacement for +.I sh +for use in the ``prog'' mailer in +.IR sendmail (8) +configuration files. +It sharply limits the commands that can be run using the +``|program'' syntax of +.I sendmail +in order to improve the over all security of your system. +Briefly, even if a ``bad guy'' can get sendmail to run a program +without going through an alias or forward file, +.I smrsh +limits the set of programs that he or she can execute. +.PP +Briefly, +.I smrsh +limits programs to be in the directory +/usr/local/ticra/bin +allowing the system administrator to choose the set of acceptable commands. +It also rejects any commands with the characters +`\`', `<', `>', `|', `;', `&', `$', `(', `)', `\er' (carriage return), +or `\en' (newline) +on the command line to prevent ``end run'' attacks. +.PP +Initial pathnames on programs are stripped, +so forwarding to ``/usr/bin/vacation'', +``/home/server/mydir/bin/vacation'', +and +``vacation'' +all actually forward to +``/usr/local/ticra/bin/vacation''. +.PP +System administrators should be conservative about populating +/usr/local/ticra/bin. +Reasonable additions are +.IR vacation (1), +.IR procmail (1), +and the like. +No matter how brow-beaten you may be, +never include any shell or shell-like program +(such as +.IR perl (1)) +in the +sm.bin +directory. +Note that this does not restrict the use of shell or perl scripts +in the sm.bin directory (using the ``#!'' syntax); +it simply disallows execution of arbitrary programs. +.SH COMPILATION +Compilation should be trivial on most systems. +You may need to use \-DPATH=\e"\fIpath\fP\e" +to adjust the default search path +(defaults to ``/bin:/usr/bin'') +and/or \-DBINDIR=\e"\fIdir\fP\e" +to change the default program directory +(defaults to ``/usr/local/ticra/bin''). +.SH FILES +/usr/local/ticra/bin \- directory for restricted programs +.SH SEE ALSO +sendmail(8) |