src/misc-progs/logwatch.c

   1 /* This file is part of the IPCop Firewall.
   2  *
   3  * This program is distributed under the terms of the GNU General Public
   4  * Licence.  See the file COPYING for details.
   5  *
   6  * Copyright (C) 2003-07-12 Robert Kerr <rkerr@go.to>
   7  *
   8  * $Id: logwatch.c,v 1.2 2003/12/11 11:25:54 riddles Exp $
   9  *
  10  */
  11
  12 #include <stdio.h>
  13 #include <unistd.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <grp.h>
  17 #include <pwd.h>
  18 #include <sys/types.h>
  19 #include "libsmooth.h"
  20 #include "setuid.h"
  21
  22 /* Lots of distros just run logwatch as root from cron, but logwatch doesn't
  23  * need any root privs, just the ability to access it's filter scripts
  24  * (/etc/log.d/) and the log files (under /var/log/). By creating a logwatch
  25  * user and group and ensuring it has read access to the logs we can run
  26  * logwatch unprivileged. Apart from the principle of least privilege running
  27  * logwatch as root turns out to be doubly a bad idea because a flaw in the way
  28  * it works:
  29  *
  30  *   http://www.securityfocus.com/archive/1/327833/2003-07-01/2003-07-07/0
  31  *
  32  * This wrapper program should be run as root, but not installed setuid root,
  33  * it's basic aim is to allow a root cron job to safely run logcheck; as such
  34  * it will drop privileges, becoming the locheck user & group then run
  35  * logcheck. In many ways this is much the same as getting cron to run
  36  *    su -s /etc/log.d/scripts/logwatch.pl
  37  * the wrapper however is able to read configuration info from /var/ipcop and
  38  * pass the correct args to logwatch
  39  */
  40
  41 int main(void)
  42 {
  43    char buffer[STRING_SIZE];
  44    struct keyvalue *kv = NULL;
  45    struct passwd *pw;
  46    gid_t groups[2];
  47    char * argv[4];
  48
  49    if(getuid())
  50    {
  51       fprintf(stderr, "logwatch should be ran by root\n");
  52       exit(1);
  53    }
  54
  55    /* Read in and verify config */
  56    kv=initkeyvalues();
  57
  58    if (!readkeyvalues(kv, CONFIG_ROOT "/logging/settings"))
  59    {
  60       fprintf(stderr, "Cannot read syslog settings\n");
  61       exit(1);
  62    }
  63
  64    if (!findkey(kv, "LOGWATCH_LEVEL", buffer))
  65    {
  66       fprintf(stderr, "Cannot read LOGWATCH_LEVEL\n");
  67       exit(1);
  68    }
  69
  70    if (strcmp(buffer,"Low") && strcmp(buffer,"Med") && strcmp(buffer,"High"))
  71    {
  72       fprintf(stderr, "Bad LOGWATCH_LEVEL: %s\n", buffer);
  73       exit(1);
  74    }
  75
  76    freekeyvalues(kv);
  77
  78
  79    /* lookup logwatch user */
  80    if(!(pw = getpwnam("logwatch")))
  81    {
  82       fprintf(stderr,"Couldn't find logwatch user.\n");
  83       exit(1);
  84    }
  85    /* paranoia... */
  86    memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
  87    endpwent();
  88
  89    /* more paranoia */
  90    if(!pw->pw_uid || !pw->pw_gid)
  91    {
  92       fprintf(stderr,"logwatch user appears to be UID or GID 0, aborting.\n");
  93       exit(1);
  94    }
  95
  96    /* drop privs */
  97    groups[0] = groups[1] = pw->pw_gid;
  98    if (setgroups(1,groups)) { perror("Couldn't clear group list"); exit(1); }
  99    if (setgid(pw->pw_gid))  { perror("Couldn't setgid(logwatch)"); exit(1); }
 100    if (setuid(pw->pw_uid))  { perror("Couldn't setuid(logwatch)"); exit(1); }
 101
 102    /* ok, spawn logwatch */
 103    argv[0] = "logwatch.pl";
 104    argv[1] = "--detail";
 105    argv[2] = buffer;
 106    argv[3] = NULL;
 107    execve("/etc/log.d/scripts/logwatch.pl", argv, trusted_env);
 108
 109    /* shouldn't get here - execve replaces current running process */
 110    perror("logwatch: execve failed");
 111    exit(1);
 112 }