g10/verify.c

   1 /* verify.c - Verify signed data
   2  * Copyright (C) 1998, 1999, 2000, 2001, 2004 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19  * USA.
  20  */
  21
  22 #include <config.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <assert.h>
  28
  29 #include "gpg.h"
  30 #include "options.h"
  31 #include "packet.h"
  32 #include "errors.h"
  33 #include "iobuf.h"
  34 #include "keydb.h"
  35 #include "util.h"
  36 #include "main.h"
  37 #include "status.h"
  38 #include "filter.h"
  39 #include "ttyio.h"
  40 #include "i18n.h"
  41
  42
  43
  44 /****************
  45  * Assume that the input is a signature and verify it without
  46  * generating any output.  With no arguments, the signature packet
  47  * is read from stdin (it may be a detached signature when not
  48  * used in batch mode). If only a sigfile is given, it may be a complete
  49  * signature or a detached signature in which case the signed stuff
  50  * is expected from stdin. With more than 1 argument, the first should
  51  * be a detached signature and the remaining files are the signed stuff.
  52  */
  53
  54 int
  55 verify_signatures( int nfiles, char **files )
  56 {
  57     IOBUF fp;
  58     armor_filter_context_t afx;
  59     progress_filter_context_t pfx;
  60     const char *sigfile;
  61     int i, rc;
  62     STRLIST sl;
  63
  64     memset( &afx, 0, sizeof afx);
  65     /* decide whether we should handle a detached or a normal signature,
  66      * which is needed so that the code later can hash the correct data and
  67      * not have a normal signature act as detached signature and ignoring the
  68      * indended signed material from the 2nd file or stdin.
  69      * 1. gpg <file        - normal
  70      * 2. gpg file         - normal (or detached)
  71      * 3. gpg file <file2  - detached
  72      * 4. gpg file file2   - detached
  73      * The question is how decide between case 2 and 3?  The only way
  74      * we can do it is by reading one byte from stdin and the unget
  75      * it; the problem here is that we may be reading from the
  76      * terminal (which could be detected using isatty() but won't work
  77      * when under contol of a pty using program (e.g. expect)) and
  78      * might get us in trouble when stdin is used for another purpose
  79      * (--passphrase-fd 0).  So we have to break with the behaviour
  80      * prior to gpg 1.0.4 by assuming that case 3 is a normal
  81      * signature (where file2 is ignored and require for a detached
  82      * signature to indicate signed material comes from stdin by using
  83      * case 4 with a file2 of "-".
  84      *
  85      * Actually we don't have to change anything here but can handle
  86      * that all quite easily in mainproc.c
  87      */
  88
  89
  90     sigfile = nfiles? *files : NULL;
  91
  92     /* open the signature file */
  93     fp = iobuf_open(sigfile);
  94     if (fp && is_secured_file (iobuf_get_fd (fp)))
  95       {
  96         iobuf_close (fp);
  97         fp = NULL;
  98         errno = EPERM;
  99       }
 100     if( !fp ) {
 101         rc = gpg_error_from_syserror ();
 102         log_error(_("can't open `%s': %s\n"),
 103                   print_fname_stdin(sigfile), strerror (errno));
 104         return rc;
 105     }
 106     handle_progress (&pfx, fp, sigfile);
 107
 108     if( !opt.no_armor && use_armor_filter( fp ) )
 109         iobuf_push_filter( fp, armor_filter, &afx );
 110
 111     sl = NULL;
 112     for(i=nfiles-1 ; i > 0 ; i-- )
 113         add_to_strlist( &sl, files[i] );
 114     rc = proc_signature_packets( NULL, fp, sl, sigfile );
 115     free_strlist(sl);
 116     iobuf_close(fp);
 117     if( (afx.no_openpgp_data && rc == -1) || rc == G10ERR_NO_DATA ) {
 118         log_error(_("the signature could not be verified.\n"
 119                    "Please remember that the signature file (.sig or .asc)\n"
 120                    "should be the first file given on the command line.\n") );
 121         rc = 0;
 122     }
 123
 124     return rc;
 125 }
 126
 127
 128 void
 129 print_file_status( int status, const char *name, int what )
 130 {
 131     char *p = xmalloc(strlen(name)+10);
 132     sprintf(p, "%d %s", what, name );
 133     write_status_text( status, p );
 134     xfree(p);
 135 }
 136
 137
 138 static int
 139 verify_one_file( const char *name )
 140 {
 141     IOBUF fp;
 142     armor_filter_context_t afx;
 143     progress_filter_context_t pfx;
 144     int rc;
 145
 146     print_file_status( STATUS_FILE_START, name, 1 );
 147     fp = iobuf_open(name);
 148     if (fp)
 149       iobuf_ioctl (fp,3,1,NULL); /* disable fd caching */
 150     if (fp && is_secured_file (iobuf_get_fd (fp)))
 151       {
 152         iobuf_close (fp);
 153         fp = NULL;
 154         errno = EPERM;
 155       }
 156     if( !fp ) {
 157         rc = gpg_error_from_syserror ();
 158         log_error(_("can't open `%s': %s\n"),
 159                   print_fname_stdin(name), strerror (errno));
 160         print_file_status( STATUS_FILE_ERROR, name, 1 );
 161         return rc;
 162     }
 163     handle_progress (&pfx, fp, name);
 164
 165     if( !opt.no_armor ) {
 166         if( use_armor_filter( fp ) ) {
 167             memset( &afx, 0, sizeof afx);
 168             iobuf_push_filter( fp, armor_filter, &afx );
 169         }
 170     }
 171
 172     rc = proc_signature_packets( NULL, fp, NULL, name );
 173     iobuf_close(fp);
 174     write_status( STATUS_FILE_DONE );
 175     return rc;
 176 }
 177
 178 /****************
 179  * Verify each file given in the files array or read the names of the
 180  * files from stdin.
 181  * Note:  This function can not handle detached signatures.
 182  */
 183 int
 184 verify_files( int nfiles, char **files )
 185 {
 186     int i;
 187
 188     if( !nfiles ) { /* read the filenames from stdin */
 189         char line[2048];
 190         unsigned int lno = 0;
 191
 192         while( fgets(line, DIM(line), stdin) ) {
 193             lno++;
 194             if( !*line || line[strlen(line)-1] != '\n' ) {
 195                 log_error(_("input line %u too long or missing LF\n"), lno );
 196                 return G10ERR_GENERAL;
 197             }
 198             /* This code does not work on MSDOS but how cares there are
 199              * also no script languages available.  We don't strip any
 200              * spaces, so that we can process nearly all filenames */
 201             line[strlen(line)-1] = 0;
 202             verify_one_file( line );
 203         }
 204
 205     }
 206     else {  /* take filenames from the array */
 207         for(i=0; i < nfiles; i++ )
 208             verify_one_file( files[i] );
 209     }
 210     return 0;
 211 }