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Date: Thu, 11 Jan 1996 21:26:39 -0600
From: Dave Bodenstab <imdave@synet.net>
Message-Id: <199601120326.VAA03933@base486>
To: questions@FreeBSD.org
Subject: Re: (fwd) "at" problem
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jgoerzen@complete.org (John Goerzen) wrote:
>
>When I am logged in as myself and su'd to root, I try issuing the following
>at command:
>
>at now + 3 minutes
>
>and then I enter:
>
>cat ~root/testfile.txt | mail -s test jgoerzen
>^D
>
>It appears to run fine.  However, when atrun gets ahold of it and tries to
>run it, I get:
>
>Jan 10 16:25:01 complete atrun[5183]: 
>Userid 0 mismatch name jgoerzen - aborting job c00d0dee1.00
>
>(line breaking added)
>
>Now I had originally logged in as jgoerzen (myself) and su'd to root.  I
>have tried it using the syntax "su", "su -l", and by the suggestion of
>somebody on IRC, "su -".  None worked.  After running su, I have checked the
>relevant environment variables, and they all seem to be fine.
>
>Help appreciated.
>
>-- John Goerzen

Been there.  Fixed it.  That's what the source is for :-)

In /usr/src/libexec/atrun/atrun.c:


    if (fscanf(stream, "#! /bin/sh\n# mail %8s %d", mailbuf, &send_mail) == 2)
    {
        mailname = mailbuf;
        pentry = getpwnam(mailname);
        if (pentry == NULL || pentry->pw_uid != uid) {
                syslog(LOG_ERR,"Userid %lu mismatch name %s - aborting job %s",
                       (unsigned long) uid, mailname, filename);
                exit(EXIT_FAILURE);
        }
    }


Thus, the problem is that the mailto uid does not match the uid running the
at job.  Probably a security thing, so it probably shouldn't go into the
distributed source, but we can make a private fix...

So...  from 2.0.5's 6/22/95 snap, /usr/src/usr.bin/at/at.c, we just make `at'
always use the effective uid to generate the at-job header:

*** 2.0	1995/08/20 18:26:26
--- 2.0.1.1	1995/08/20 18:27:19
***************
*** 271,290 ****
      if((fp = fdopen(fdes, "w")) == NULL)
  	panic("Cannot reopen atjob file");
  
!     /* Get the userid to mail to, first by trying getlogin(), which reads
!      * /etc/utmp, then from LOGNAME, finally from getpwuid().
       */
!     mailname = getlogin();
!     if (mailname == NULL)
! 	mailname = getenv("LOGNAME");
! 
!     if ((mailname == NULL) || (mailname[0] == '\0')
! 	|| (strlen(mailname) > 8) || (getpwnam(mailname)==NULL))
!     {
! 	pass_entry = getpwuid(getuid());
! 	if (pass_entry != NULL)
! 	    mailname = pass_entry->pw_name;
!     }
  
      if (atinput != (char *) NULL)
      {
--- 271,283 ----
      if((fp = fdopen(fdes, "w")) == NULL)
  	panic("Cannot reopen atjob file");
  
!     /* Get the userid to mail to from getpwuid(geteuid()).
       */
!     pass_entry = getpwuid(geteuid());
!     if (pass_entry != NULL)
! 	mailname = pass_entry->pw_name;
!     else
! 	mailname = "root";
  
      if (atinput != (char *) NULL)
      {


Dave Bodenstab
imdave@synet.net