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 #include <unistd.h> /* for isatty() */
  29
  30 #include "options.h"
  31 #include "packet.h"
  32 #include "errors.h"
  33 #include "iobuf.h"
  34 #include "keydb.h"
  35 #include "memory.h"
  36 #include "util.h"
  37 #include "main.h"
  38 #include "status.h"
  39 #include "filter.h"
  40 #include "ttyio.h"
  41 #include "i18n.h"
  42
  43
  44
  45 /****************
  46  * Assume that the input is a signature and verify it without
  47  * generating any output.  With no arguments, the signature packet
  48  * is read from stdin (it may be a detached signature when not
  49  * used in batch mode). If only a sigfile is given, it may be a complete
  50  * signature or a detached signature in which case the signed stuff
  51  * is expected from stdin. With more than 1 argument, the first should
  52  * be a detached signature and the remaining files are the signed stuff.
  53  */
  54
  55 int
  56 verify_signatures( int nfiles, char **files )
  57 {
  58     IOBUF fp;
  59     armor_filter_context_t afx;
  60     progress_filter_context_t pfx;
  61     const char *sigfile;
  62     int i, rc;
  63     STRLIST sl;
  64
  65     memset( &afx, 0, sizeof afx);
  66     /* decide whether we should handle a detached or a normal signature,
  67      * which is needed so that the code later can hash the correct data and
  68      * not have a normal signature act as detached signature and ignoring the
  69      * indended signed material from the 2nd file or stdin.
  70      * 1. gpg <file        - normal
  71      * 2. gpg file         - normal (or detached)
  72      * 3. gpg file <file2  - detached
  73      * 4. gpg file file2   - detached
  74      * The question is how decide between case 2 and 3?  The only way
  75      * we can do it is by reading one byte from stdin and the unget
  76      * it; the problem here is that we may be reading from the
  77      * terminal (which could be detected using isatty() but won't work
  78      * when under contol of a pty using program (e.g. expect)) and
  79      * might get us in trouble when stdin is used for another purpose
  80      * (--passphrase-fd 0).  So we have to break with the behaviour
  81      * prior to gpg 1.0.4 by assuming that case 3 is a normal
  82      * signature (where file2 is ignored and require for a detached
  83      * signature to indicate signed material comes from stdin by using
  84      * case 4 with a file2 of "-".
  85      *
  86      * Actually we don't have to change anything here but can handle
  87      * that all quite easily in mainproc.c
  88      */
  89
  90
  91     sigfile = nfiles? *files : NULL;
  92
  93     /* open the signature file */
  94     fp = iobuf_open(sigfile);
  95     if (fp && is_secured_file (iobuf_get_fd (fp)))
  96       {
  97         iobuf_close (fp);
  98         fp = NULL;
  99         errno = EPERM;
 100       }
 101     if( !fp ) {
 102         log_error(_("can't open `%s'\n"), print_fname_stdin(sigfile));
 103         return G10ERR_OPEN_FILE;
 104     }
 105     handle_progress (&pfx, fp, sigfile);
 106
 107     if( !opt.no_armor && use_armor_filter( fp ) )
 108         iobuf_push_filter( fp, armor_filter, &afx );
 109
 110     sl = NULL;
 111     for(i=nfiles-1 ; i > 0 ; i-- )
 112         add_to_strlist( &sl, files[i] );
 113     rc = proc_signature_packets( NULL, fp, sl, sigfile );
 114     free_strlist(sl);
 115     iobuf_close(fp);
 116     if( (afx.no_openpgp_data && rc == -1) || rc == G10ERR_NO_DATA ) {
 117         log_error(_("the signature could not be verified.\n"
 118                    "Please remember that the signature file (.sig or .asc)\n"
 119                    "should be the first file given on the command line.\n") );
 120         rc = 0;
 121     }
 122
 123     return rc;
 124 }
 125
 126
 127 void
 128 print_file_status( int status, const char *name, int what )
 129 {
 130     char *p = xmalloc(strlen(name)+10);
 131     sprintf(p, "%d %s", what, name );
 132     write_status_text( status, p );
 133     xfree(p);
 134 }
 135
 136
 137 static int
 138 verify_one_file( const char *name )
 139 {
 140     IOBUF fp;
 141     armor_filter_context_t afx;
 142     progress_filter_context_t pfx;
 143     int rc;
 144
 145     print_file_status( STATUS_FILE_START, name, 1 );
 146     fp = iobuf_open(name);
 147     if (fp)
 148       iobuf_ioctl (fp,3,1,NULL); /* disable fd caching */
 149     if (fp && is_secured_file (iobuf_get_fd (fp)))
 150       {
 151         iobuf_close (fp);
 152         fp = NULL;
 153         errno = EPERM;
 154       }
 155     if( !fp ) {
 156         print_file_status( STATUS_FILE_ERROR, name, 1 );
 157         log_error(_("can't open `%s'\n"), print_fname_stdin(name));
 158         return G10ERR_OPEN_FILE;
 159     }
 160     handle_progress (&pfx, fp, name);
 161
 162     if( !opt.no_armor ) {
 163         if( use_armor_filter( fp ) ) {
 164             memset( &afx, 0, sizeof afx);
 165             iobuf_push_filter( fp, armor_filter, &afx );
 166         }
 167     }
 168
 169     rc = proc_signature_packets( NULL, fp, NULL, name );
 170     iobuf_close(fp);
 171     write_status( STATUS_FILE_DONE );
 172     return rc;
 173 }
 174
 175 /****************
 176  * Verify each file given in the files array or read the names of the
 177  * files from stdin.
 178  * Note:  This function can not handle detached signatures.
 179  */
 180 int
 181 verify_files( int nfiles, char **files )
 182 {
 183     int i;
 184
 185     if( !nfiles ) { /* read the filenames from stdin */
 186         char line[2048];
 187         unsigned int lno = 0;
 188
 189         while( fgets(line, DIM(line), stdin) ) {
 190             lno++;
 191             if( !*line || line[strlen(line)-1] != '\n' ) {
 192                 log_error(_("input line %u too long or missing LF\n"), lno );
 193                 return G10ERR_GENERAL;
 194             }
 195             /* This code does not work on MSDOS but how cares there are
 196              * also no script languages available.  We don't strip any
 197              * spaces, so that we can process nearly all filenames */
 198             line[strlen(line)-1] = 0;
 199             verify_one_file( line );
 200         }
 201
 202     }
 203     else {  /* take filenames from the array */
 204         for(i=0; i < nfiles; i++ )
 205             verify_one_file( files[i] );
 206     }
 207     return 0;
 208 }