diff options
Diffstat (limited to 'contrib/sendmail/smrsh/README')
| -rw-r--r-- | contrib/sendmail/smrsh/README | 156 |
1 files changed, 0 insertions, 156 deletions
diff --git a/contrib/sendmail/smrsh/README b/contrib/sendmail/smrsh/README deleted file mode 100644 index 7e22f86bd8f5b..0000000000000 --- a/contrib/sendmail/smrsh/README +++ /dev/null @@ -1,156 +0,0 @@ - -README smrsh - sendmail restricted shell. - -This README file is provided as a courtesy of the CERT Coordination Center, -Software Engineering Institute, Carnegie Mellon University. This file is -intended as a supplement to the CERT advisory CA-93:16.sendmail.vulnerability, -and to the software, smrsh.c, written by Eric Allman. - - - -The smrsh(8) program is intended as a replacement for /bin/sh in the -program mailer definition of sendmail(8). This README file describes -the steps needed to compile and install smrsh. - -smrsh is a restricted shell utility that provides the ability to -specify, through a configuration, an explicit list of executable -programs. When used in conjunction with sendmail, smrsh effectively -limits sendmail's scope of program execution to only those programs -specified in smrsh's configuration. - -smrsh has been written with portability in mind, and uses traditional -Unix library utilities. As such, smrsh should compile on most -Unix C compilers. - -smrsh should build on most systems with the enclosed Build script: - - host.domain% sh Build - -To compile smrsh.c by hand, use the following command: - - host.domain% cc -o smrsh smrsh.c - -For machines that provide dynamic linking, it is advisable to compile -smrsh without dynamic linking. As an example with the Sun Microsystems -compiler, you should compile with the -Bstatic option. - - host.domain% cc -Bstatic -o smrsh smrsh.c - or - host.domain% sh Build LDOPTS=-Bstatic - -With gcc, the GNU C compiler, use the -static option. - - host.domain% cc -static -o smrsh smrsh.c - or - host.domain% sh Build LDOPTS=-static - - - -As root, install smrsh in /usr/libexec. Using the Build script: - - host.domain# sh Build install - -For manual installation: install smrsh in the /usr/libexec -directory, with mode 511. - - host.domain# mv smrsh /usr/libexec - host.domain# chmod 511 /usr/libexec/smrsh - - - -Next, determine the list of commands that smrsh should allow sendmail -to run. This list of allowable commands can be determined by: - - 1. examining your /etc/mail/aliases file, to indicate what commands - are being used by the system. - - 2. surveying your host's .forward files, to determine what - commands users have specified. - -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. - -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 -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 -a change in smrsh.c. - - -You will have to be root to make these modifications. - -After creating the /usr/adm/sm.bin 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 -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: - - host.domain# cd /usr/adm/sm.bin - host.domain# ln -s /usr/ucb/vacation vacation - - - - -After populating the /usr/adm/sm.bin 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. - -Typically, the program mailer is defined by a single line in the -sendmail configuration file, sendmail.cf. This file is traditionally -found in the /etc, /usr/lib or /etc/mail directories, depending on -the UNIX vendor. - -If you are unsure of the location of the actual sendmail configuration -file, a search of the strings(1) output of the sendmail binary, will -help to locate it. - -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. - -As an example: - -In most Sun Microsystems' sendmail.cf files, the line is: -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 - ^^^^^^^^^^^^^^^^^^ - -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 $u - - -After modifying the Mprog definition in the sendmail.cf file, if a frozen -configuration file is being used, it is essential to create a new one. -You can determine if you need a frozen configuration by discovering -if a sendmail.fc file currently exists in either the /etc/, /usr/lib, -or /etc/mail directories. The specific location can be determined using -a search of the strings(1) output of the sendmail binary. - -In order to create a new frozen configuration, if it is required: - host.domain# /usr/lib/sendmail -bz - -Now re-start the sendmail process. An example of how to do this on -a typical system follows: - - host.domain# cat /var/run/sendmail.pid - 130 - /usr/sbin/sendmail -bd -q30m - host.domain# /bin/kill -15 130 - host.domain# /usr/sbin/sendmail -bd -q30m - - -$Revision: 8.8 $, Last updated $Date: 2001/01/24 00:05:58 $ |