unshar business

[Jim Budler]

In article <419 at eda.com> jim at eda.com (Jim Budler) writes:
| In article <167 at ecicrl.UUCP> clewis at ecicrl.UUCP (Chris Lewis) writes:

Chris doesn't like what I said, but one of the things I said was
that I intended to make a couple of changes to Cathy's uns.c and then
run it out from under uuhosts instead of under uuhosts/mapsh.

I'll put my mouth where my mouth was, since I am on vacation and
have been spurred to find the time. I do not do this because my previous
way of running it was insecure (under uuhosts and mapsh), but because
with these trivial changes the security is maintained, while the
processing is simplified. 

An advantage gained compared to the original uuhosts, 
with or without mapsh, is increased security. mapsh prevented most
problems, but could have been susceptible to malicious inode usage.

Uuhosts itself did *limited* checking of the map shar before passing it
to sh.

Another advantage over the original uuhosts is a single letter to
news (aliased to me) logging the actions, instead of a letter for
each map file.

The changes I made:
Lengthened the input filename buffer to allow the method I use,
detailed below.

Lengthened the line buffer to allow longer lined shars.

Dissallowed '/' in the output filenames. It must be run in the
map directory.

Thank you Cathy Segedy <decvax!gsg!segedy> for uns.c

Details:
My news sys file entry related to maps:
=================
maps:world,comp.mail.maps:F:/usr/spool/news/maps/comp.mail.maps/Batch
=================

My crontab entry:
=================
30 5 * * * /usr/spool/news/maps/comp.mail.maps/Process > /dev/null 2>&1
=================
Note: I have a sysV type crontab with different crontabs for each user.
	This crontab entry runs as news, not root.

A v7/BSD one *might* look like:
=================
30 5 * * * /bin/su news < /usr/spool/news/maps/comp.mail.maps/Process > /dev/null 2>&1
=================
I could be wrong about that, check your manual.

The script /usr/spool/news/maps/comp.mail.maps/Process :
=================
#! /bin/sh
# unbatch the maps, then make install paths

umask 2
cd /usr/spool/news/maps/comp.mail.maps
if [ -f Batch ]; then
#	/usr/local/bin/uuhosts -unbatch
# using uns instead of uuhosts to unbatch
		mv Batch Batch.working
		for file in `cat Batch.working`
		do
				uns $file >> Batch.log
		done
# use uuhosts to create the index file
		/usr/local/bin/uuhosts -i
		mail -s 'Map Process Log' postmaster < Batch.log
		rm -f Batch.working Batch.log
		make -s install
fi
=================
And finally diff. By the way for you who have been listening, Cathy's program
did not use gets(), it always used fgets().
=================
*** /tmp/,RCSt1a26060	Fri Dec 23 12:50:39 1988
--- uns.c	Fri Dec 23 12:50:19 1988
***************
*** 26,35 ****
  after the SHAR_EOF.
  Someone might wish to shorten MAXLIN  (do map files have a line limit?)
  */
  
  #include <stdio.h>
  
! #define MAXLIN 256
  
  main(argc,argv)
  int argc;
--- 26,39 ----
  after the SHAR_EOF.
  Someone might wish to shorten MAXLIN  (do map files have a line limit?)
  */
+ /* lengthened MAXLIN cause someone said they found longer lines in
+  * a shar file. I don't know if this was a map shar file.
+  * Is there a line length on a map shar file? - jim budler
+  */
  
  #include <stdio.h>
  
! #define MAXLIN 1024
  
  main(argc,argv)
  int argc;
***************
*** 38,50 ****
  	FILE *fp, *fp2;
  	char buffer[MAXLIN];
  	int at_beginning, at_end;
! 	char filename[20], file2[20];
  
  	at_beginning = 0;
  	at_end = 0;
  
  	if(argc != 2){
! 	    printf("bad arguements\n");
  	    exit(1);
  	}
  
--- 42,58 ----
  	FILE *fp, *fp2;
  	char buffer[MAXLIN];
  	int at_beginning, at_end;
! 	char filename[1024], file2[20];
! /* lengthened the buffer for filename. The full path for filename is
!  * presented by my method of passing the input name to uns, so
!  * a longer buffer was required than 20 char. - jim budler.
!  */
  
  	at_beginning = 0;
  	at_end = 0;
  
  	if(argc != 2){
! 	    printf("bad arguments\n");
  	    exit(1);
  	}
  
***************
*** 68,73 ****
--- 76,86 ----
  	    }
  	    printf("removing end-of-line while copying\n");
  	    strncpy(file2,&buffer[20],(strlen(&buffer[20]) - 1));
+ /* check for / in output filenames. Disallow such files - jim budler */
+ 		if ( rindex ( file2, '/') != NULL ) {
+ 			printf ("%s contains /, aborting.\n", file2);
+ 				exit(1);
+ 		}
  	    printf("opening file {%s}\n",file2);
  	    if((fp2 = fopen(file2, "w")) ==  NULL) {
  		printf("can not open file {%s}\n",file2);

=================
-- 
Jim Budler   address = uucp: ...!{decwrl,uunet}!eda!jim OR domain: jim at eda.com
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