common/sysutils.c

   1 /* sysutils.c -  system helpers
   2  * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  19  */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #ifdef HAVE_STAT
  28 #include <sys/stat.h>
  29 #endif
  30 #if defined(__linux__) && defined(__alpha__) && __GLIBC__ < 2
  31   #include <asm/sysinfo.h>
  32   #include <asm/unistd.h>
  33 #endif
  34 #ifdef HAVE_SETRLIMIT
  35   #include <time.h>
  36   #include <sys/time.h>
  37   #include <sys/resource.h>
  38 #endif
  39 #include "util.h"
  40 #include "i18n.h"
  41
  42 #include "sysutils.h"
  43
  44 #if defined(__linux__) && defined(__alpha__) && __GLIBC__ < 2
  45 #warning using trap_unaligned
  46 static int
  47 setsysinfo(unsigned long op, void *buffer, unsigned long size,
  48                      int *start, void *arg, unsigned long flag)
  49 {
  50     return syscall(__NR_osf_setsysinfo, op, buffer, size, start, arg, flag);
  51 }
  52
  53 void
  54 trap_unaligned(void)
  55 {
  56     unsigned int buf[2];
  57
  58     buf[0] = SSIN_UACPROC;
  59     buf[1] = UAC_SIGBUS | UAC_NOPRINT;
  60     setsysinfo(SSI_NVPAIRS, buf, 1, 0, 0, 0);
  61 }
  62 #else
  63 void
  64 trap_unaligned(void)
  65 {  /* dummy */
  66 }
  67 #endif
  68
  69
  70 int
  71 disable_core_dumps (void)
  72 {
  73  #ifdef HAVE_DOSISH_SYSTEM
  74     return 0;
  75  #else
  76   #ifdef HAVE_SETRLIMIT
  77     struct rlimit limit;
  78
  79     limit.rlim_cur = 0;
  80     limit.rlim_max = 0;
  81     if( !setrlimit( RLIMIT_CORE, &limit ) )
  82         return 0;
  83     if( errno != EINVAL && errno != ENOSYS )
  84         log_fatal (_("can't disable core dumps: %s\n"), strerror(errno) );
  85   #endif
  86     return 1;
  87  #endif
  88 }
  89
  90
  91
  92 /* Return a string which is used as a kind of process ID */
  93 const byte *
  94 get_session_marker( size_t *rlen )
  95 {
  96     static byte marker[SIZEOF_UNSIGNED_LONG*2];
  97     static int initialized;
  98
  99     if ( !initialized ) {
 100         volatile ulong aa, bb; /* we really want the uninitialized value */
 101         ulong a, b;
 102
 103         initialized = 1;
 104         /* also this marker is guessable it is not easy to use this
 105          * for a faked control packet because an attacker does not
 106          * have enough control about the time the verification does
 107          * take place.  Of course, we can add just more random but
 108          * than we need the random generator even for verification
 109          * tasks - which does not make sense. */
 110         a = aa ^ (ulong)getpid();
 111         b = bb ^ (ulong)time(NULL);
 112         memcpy( marker, &a, SIZEOF_UNSIGNED_LONG );
 113         memcpy( marker+SIZEOF_UNSIGNED_LONG, &b, SIZEOF_UNSIGNED_LONG );
 114     }
 115     *rlen = sizeof(marker);
 116     return marker;
 117 }
 118
 119
 120 #if 0 /* not yet needed */
 121 int
 122 check_permissions(const char *path,int extension,int checkonly)
 123 {
 124 #if defined(HAVE_STAT) && !defined(HAVE_DOSISH_SYSTEM)
 125   char *tmppath;
 126   struct stat statbuf;
 127   int ret=1;
 128   int isdir=0;
 129
 130   if(opt.no_perm_warn)
 131     return 0;
 132
 133   if(extension && path[0]!=DIRSEP_C)
 134     {
 135       if(strchr(path,DIRSEP_C))
 136         tmppath=make_filename(path,NULL);
 137       else
 138         tmppath=make_filename(GNUPG_LIBDIR,path,NULL);
 139     }
 140   else
 141     tmppath=m_strdup(path);
 142
 143   /* It's okay if the file doesn't exist */
 144   if(stat(tmppath,&statbuf)!=0)
 145     {
 146       ret=0;
 147       goto end;
 148     }
 149
 150   isdir=S_ISDIR(statbuf.st_mode);
 151
 152   /* Per-user files must be owned by the user.  Extensions must be
 153      owned by the user or root. */
 154   if((!extension && statbuf.st_uid != getuid()) ||
 155      (extension && statbuf.st_uid!=0 && statbuf.st_uid!=getuid()))
 156     {
 157       if(!checkonly)
 158         log_info(_("Warning: unsafe ownership on %s \"%s\"\n"),
 159                  isdir?"directory":extension?"extension":"file",path);
 160       goto end;
 161     }
 162
 163   /* This works for both directories and files - basically, we don't
 164      care what the owner permissions are, so long as the group and
 165      other permissions are 0 for per-user files, and non-writable for
 166      extensions. */
 167   if((extension && (statbuf.st_mode & (S_IWGRP|S_IWOTH)) !=0) ||
 168      (!extension && (statbuf.st_mode & (S_IRWXG|S_IRWXO)) != 0))
 169     {
 170       char *dir;
 171
 172       /* However, if the directory the directory/file is in is owned
 173          by the user and is 700, then this is not a problem.
 174          Theoretically, we could walk this test up to the root
 175          directory /, but for the sake of sanity, I'm stopping at one
 176          level down. */
 177
 178       dir= make_dirname (tmppath);
 179       if(stat(dir,&statbuf)==0 && statbuf.st_uid==getuid() &&
 180          S_ISDIR(statbuf.st_mode) && (statbuf.st_mode & (S_IRWXG|S_IRWXO))==0)
 181         {
 182           xfree (dir);
 183           ret=0;
 184           goto end;
 185         }
 186
 187       m_free(dir);
 188
 189       if(!checkonly)
 190         log_info(_("Warning: unsafe permissions on %s \"%s\"\n"),
 191                  isdir?"directory":extension?"extension":"file",path);
 192       goto end;
 193     }
 194
 195   ret=0;
 196
 197  end:
 198   m_free(tmppath);
 199
 200   return ret;
 201
 202 #endif /* HAVE_STAT && !HAVE_DOSISH_SYSTEM */
 203
 204   return 0;
 205 }
 206 #endif