--- ./smrsh/README.org Tue Sep 30 09:59:46 2003 +++ ./smrsh/README Tue Sep 30 10:04:24 2003 @@ -6,7 +6,7 @@ intended as a supplement to the CERT advisory CA-93:16.sendmail.vulnerability, and to the software, smrsh.c, written by Eric Allman. - +* Modified by PLD Team to reflect different paths. * The smrsh(8) program is intended as a replacement for /bin/sh in the program mailer definition of sendmail(8). This README file describes @@ -47,24 +47,24 @@ The following C defines can be set defined to change the search path and the bin directory used by smrsh. --DSMRSH_PATH=\"path\" \"/bin:/usr/bin:/usr/ucb\" The default search +-DSMRSH_PATH=\"path\" \"/bin:/usr/bin:/usr/bin\" The default search path. --DSMRSH_CMDDIR=\"dir\" \"/usr/adm/sm.bin\" The default smrsh +-DSMRSH_CMDDIR=\"dir\" \"/etc/smrsh\" The default smrsh program directory These can be added to the devtools/Site/site.config.m4 file using the global M4 macro confENVDEF or the smrsh specific M4 macro conf_smrsh_ENVDEF. -As root, install smrsh in /usr/libexec. Using the Build script: +As root, install smrsh in /usr/sbin. Using the Build script: host.domain# sh ./Build install -For manual installation: install smrsh in the /usr/libexec +For manual installation: install smrsh in the /usr/sbin directory, with mode 511. - host.domain# mv smrsh /usr/libexec - host.domain# chmod 511 /usr/libexec/smrsh + host.domain# mv smrsh /usr/sbin + host.domain# chmod 511 /usr/sbin/smrsh @@ -79,14 +79,14 @@ See the man page for aliases(5) if you are unfamiliar with the format of these specifications. Additionally, you should include in the list, -popular commands such as /usr/ucb/vacation. +popular commands such as /usr/bin/vacation. You should NOT include interpreter programs such as sh(1), csh(1), perl(1), uudecode(1) or the stream editor sed(1) in your list of acceptable commands. If your platform doesn't have a default SMRSH_CMDDIR setting, you will -next need to create the directory /usr/adm/sm.bin and populate +next need to create the directory /etc/smrsh and populate it with the programs that your site feels are allowable for sendmail to execute. This directory is explicitly specified in the source code for smrsh, so changing this directory must be accompanied with @@ -95,22 +95,22 @@ You will have to be root to make these modifications. -After creating the /usr/adm/sm.bin directory, either copy the programs +After creating the /etc/smrsh directory, either copy the programs to the directory, or establish links to the allowable programs from -/usr/adm/sm.bin. Change the file permissions, so that these programs +/etc/smrsh. Change the file permissions, so that these programs can not be modified by non-root users. If you use links, you should ensure that the target programs are not modifiable. To allow the popular vacation(1) program by creating a link in the -/usr/adm/sm.bin directory, you should: +/etc/smrsh directory, you should: - host.domain# cd /usr/adm/sm.bin - host.domain# ln -s /usr/ucb/vacation vacation + host.domain# cd /etc/smrsh + host.domain# ln -s /usr/bin/vacation vacation -After populating the /usr/adm/sm.bin directory, you can now configure +After populating the /etc/smrsh directory, you can now configure sendmail to use the restricted shell. Save the current sendmail.cf file prior to modifying it, as a prudent precaution. @@ -125,7 +125,7 @@ In order to configure sendmail to use smrsh, you must modify the Mprog definition in the sendmail.cf file, by replacing the /bin/sh specification -with /usr/libexec/smrsh. +with /usr/sbin/smrsh. As an example: @@ -133,14 +133,14 @@ Mprog, P=/bin/sh, F=lsDFMeuP, S=10, R=20, A=sh -c $u which should be changed to: -Mprog, P=/usr/libexec/smrsh, F=lsDFMeuP, S=10, R=20, A=sh -c $u +Mprog, P=/usr/sbin/smrsh, F=lsDFMeuP, S=10, R=20, A=sh -c $u ^^^^^^^^^^^^^^^^^^ A more generic line may be: Mprog, P=/bin/sh, F=lsDFM, A=sh -c $u and should be changed to; -Mprog, P=/usr/libexec/smrsh, F=lsDFM, A=sh -c $u +Mprog, P=/usr/sbin/smrsh, F=lsDFM, A=sh -c $u After modifying the Mprog definition in the sendmail.cf file, if a frozen @@ -151,7 +151,7 @@ a search of the strings(1) output of the sendmail binary. In order to create a new frozen configuration, if it is required: - host.domain# /usr/lib/sendmail -bz + host.domain# /usr/sbin/sendmail -bz Now re-start the sendmail process. An example of how to do this on a typical system follows: --- ./smrsh/smrsh.8.org Tue Sep 30 10:04:39 2003 +++ ./smrsh/smrsh.8 Tue Sep 30 10:12:49 2003 @@ -39,7 +39,7 @@ .I smrsh limits programs to be in a single directory, by default -/usr/adm/sm.bin, +/etc/smrsh, allowing the system administrator to choose the set of acceptable commands, and to the shell builtin commands ``exec'', ``exit'', and ``echo''. It also rejects any commands with the characters @@ -50,16 +50,16 @@ ``"|exec /usr/local/bin/filter || exit 75"'' .PP Initial pathnames on programs are stripped, -so forwarding to ``/usr/ucb/vacation'', +so forwarding to ``/usr/bin/vacation'', ``/usr/bin/vacation'', ``/home/server/mydir/bin/vacation'', and ``vacation'' all actually forward to -``/usr/adm/sm.bin/vacation''. +``/etc/smrsh/vacation''. .PP System administrators should be conservative about populating -the sm.bin directory. +the /etc/smrsh directory. For example, a reasonable additions is .IR vacation (1), and the like. @@ -68,10 +68,10 @@ (such as .IR perl (1)) in the -sm.bin +/etc/smrsh directory. Note that this does not restrict the use of shell or perl scripts -in the sm.bin directory (using the ``#!'' syntax); +in the /etc/smrsh directory (using the ``#!'' syntax); it simply disallows execution of arbitrary programs. Also, including mail filtering programs such as .IR procmail (1) @@ -79,15 +79,7 @@ .IR procmail (1) allows users to run arbitrary programs in their .IR procmailrc (5). -.SH COMPILATION -Compilation should be trivial on most systems. -You may need to use \-DSMRSH_PATH=\e"\fIpath\fP\e" -to adjust the default search path -(defaults to ``/bin:/usr/bin:/usr/ucb'') -and/or \-DSMRSH_CMDDIR=\e"\fIdir\fP\e" -to change the default program directory -(defaults to ``/usr/adm/sm.bin''). .SH FILES -/usr/adm/sm.bin \- default directory for restricted programs on most OSs +/etc/smrsh \- directory for restricted programs .PP /var/adm/sm.bin \- directory for restricted programs on HP UX and Solaris --- ./smrsh/smrsh.c.org Tue Sep 30 10:12:59 2003 +++ ./smrsh/smrsh.c Tue Sep 30 10:14:02 2003 @@ -77,7 +77,7 @@ # ifdef SMRSH_CMDDIR # define CMDDIR SMRSH_CMDDIR # else /* SMRSH_CMDDIR */ -# define CMDDIR "/usr/adm/sm.bin" +# define CMDDIR "/etc/smrsh" # endif /* SMRSH_CMDDIR */ #endif /* ! CMDDIR */ @@ -89,7 +89,7 @@ # ifdef SMRSH_PATH # define PATH SMRSH_PATH # else /* SMRSH_PATH */ -# define PATH "/bin:/usr/bin:/usr/ucb" +# define PATH "/bin:/usr/bin:/usr/sbin" # endif /* SMRSH_PATH */ #endif /* ! PATH */