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5c599e4f6e
gnupg/g10/plaintext.c
Werner Koch a5ca45e616 gpg: Make the use of "--verify FILE" for detached sigs harder. 
* g10/openfile.c (open_sigfile): Factor some code out to ...
(get_matching_datafile): new function.
* g10/plaintext.c (hash_datafiles): Do not try to find matching file
in batch mode.
* g10/mainproc.c (check_sig_and_print): Print a warning if a possibly
matching data file is not used by a standard signatures.
--

Allowing to use the abbreviated form for detached signatures is a long
standing bug which has only been noticed by the public with the
release of 2.1.0.  :-(

What we do is to remove the ability to check detached signature in
--batch using the one file abbreviated mode.  This should exhibit
problems in scripts which use this insecure practice.  We also print a
warning if a matching data file exists but was not considered because
the detached signature was actually a standard signature:

  gpgv: Good signature from "Werner Koch (dist sig)"
  gpgv: WARNING: not a detached signature; \
  file 'gnupg-2.1.0.tar.bz2' was NOT verified!

We can only print a warning because it is possible that a standard
signature is indeed to be verified but by coincidence a file with a
matching name is stored alongside the standard signature.

Reported-by: Simon Nicolussi (to gnupg-users on Nov 7)
Signed-off-by: Werner Koch <wk@gnupg.org>

(backported from commit 69384568f6)
2014-11-14 09:36:19 +01:00

672 lines
18 KiB
C
Raw Blame History

/* plaintext.c - process plaintext packets
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
* 2006 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <sys/types.h>
#ifdef HAVE_DOSISH_SYSTEM
#include <fcntl.h> /* for setmode() */
#endif
#include "gpg.h"
#include "util.h"
#include "options.h"
#include "packet.h"
#include "ttyio.h"
#include "filter.h"
#include "main.h"
#include "status.h"
#include "i18n.h"
/****************
* Handle a plaintext packet. If MFX is not NULL, update the MDs
* Note: we should use the filter stuff here, but we have to add some
* easy mimic to set a read limit, so we calculate only the
* bytes from the plaintext.
*/
int
handle_plaintext( PKT_plaintext *pt, md_filter_context_t *mfx,
int nooutput, int clearsig )
{
char *fname = NULL;
FILE *fp = NULL;
static off_t count=0;
int rc = 0;
int c;
int convert = (pt->mode == 't' || pt->mode == 'u');
#ifdef __riscos__
int filetype = 0xfff;
#endif
/* Let people know what the plaintext info is. This allows the
receiving program to try and do something different based on
the format code (say, recode UTF-8 to local). */
if(!nooutput && is_status_enabled())
{
char status[50];
/* Better make sure that stdout has been flushed in case the
output will be written to it. This is to make sure that no
not-yet-flushed stuff will be written after the plaintext
status message. */
fflush (stdout);
sprintf(status,"%X %lu ",(byte)pt->mode,(ulong)pt->timestamp);
write_status_text_and_buffer(STATUS_PLAINTEXT,
status,pt->name,pt->namelen,0);
if(!pt->is_partial)
{
sprintf(status,"%lu",(ulong)pt->len);
write_status_text(STATUS_PLAINTEXT_LENGTH,status);
}
}
/* create the filename as C string */
if( nooutput )
;
else if( opt.outfile ) {
fname = xmalloc( strlen( opt.outfile ) + 1);
strcpy(fname, opt.outfile );
}
else if( pt->namelen == 8 && !memcmp( pt->name, "_CONSOLE", 8 ) ) {
log_info(_("data not saved; use option \"--output\" to save it\n"));
nooutput = 1;
}
else if( !opt.flags.use_embedded_filename ) {
fname = make_outfile_name( iobuf_get_real_fname(pt->buf) );
if( !fname )
fname = ask_outfile_name( pt->name, pt->namelen );
if( !fname ) {
rc = gpg_error (GPG_ERR_GENERAL); /* Can't create file. */
goto leave;
}
}
else
fname=utf8_to_native(pt->name,pt->namelen,0);
if( nooutput )
;
else if ( iobuf_is_pipe_filename (fname) || !*fname)
{
/* No filename or "-" given; write to stdout. */
fp = stdout;
#ifdef HAVE_DOSISH_SYSTEM
setmode ( fileno(fp) , O_BINARY );
#endif
}
else {
while( !overwrite_filep (fname) ) {
char *tmp = ask_outfile_name (NULL, 0);
if ( !tmp || !*tmp ) {
xfree (tmp);
rc = gpg_error (GPG_ERR_GENERAL); /* G10ERR_CREATE_FILE*/
goto leave;
}
xfree (fname);
fname = tmp;
}
}
#ifndef __riscos__
if( fp || nooutput )
;
else if (is_secured_filename (fname))
{
errno = EPERM;
rc = gpg_error_from_syserror ();
log_error(_("error creating `%s': %s\n"), fname, strerror(errno) );
goto leave;
}
else if( !(fp = fopen(fname,"wb")) ) {
rc = gpg_error_from_syserror ();
log_error(_("error creating `%s': %s\n"), fname, strerror(errno) );
goto leave;
}
#else /* __riscos__ */
/* If no output filename was given, i.e. we constructed it,
convert all '.' in fname to '/' but not vice versa as
we don't create directories! */
if( !opt.outfile )
for( c=0; fname[c]; ++c )
if( fname[c] == '.' )
fname[c] = '/';
if( fp || nooutput )
;
else {
fp = fopen(fname,"wb");
if( !fp ) {
log_error(_("error creating `%s': %s\n"), fname, strerror(errno) );
rc = G10ERR_CREATE_FILE;
if (errno == 106)
log_info("Do output file and input file have the same name?\n");
goto leave;
}
/* If there's a ,xxx extension in the embedded filename,
use that, else check whether the user input (in fname)
has a ,xxx appended, then use that in preference */
if( (c = riscos_get_filetype_from_string( pt->name,
pt->namelen )) != -1 )
filetype = c;
if( (c = riscos_get_filetype_from_string( fname,
strlen(fname) )) != -1 )
filetype = c;
riscos_set_filetype_by_number(fname, filetype);
}
#endif /* __riscos__ */
if( !pt->is_partial ) {
/* We have an actual length (which might be zero). */
if (clearsig) {
log_error ("clearsig encountered while not expected\n");
rc = G10ERR_UNEXPECTED;
goto leave;
}
if( convert ) { /* text mode */
for( ; pt->len; pt->len-- ) {
if( (c = iobuf_get(pt->buf)) == -1 ) {
rc = gpg_error_from_syserror ();
log_error ("problem reading source (%u bytes remaining)\n",
(unsigned)pt->len);
goto leave;
}
if( mfx->md )
gcry_md_putc (mfx->md, c );
#ifndef HAVE_DOSISH_SYSTEM
if( c == '\r' ) /* convert to native line ending */
continue; /* fixme: this hack might be too simple */
#endif
if( fp )
{
if(opt.max_output && (++count)>opt.max_output)
{
log_error ("error writing to `%s': %s\n",
fname,"exceeded --max-output limit\n");
rc = gpg_error (GPG_ERR_TOO_LARGE);
goto leave;
}
else if( putc( c, fp ) == EOF )
{
if (ferror (fp))
rc = gpg_error_from_syserror ();
else
rc = gpg_error (GPG_ERR_EOF);
log_error ("error writing to `%s': %s\n",
fname, strerror(errno) );
goto leave;
}
}
}
}
else { /* binary mode */
byte *buffer = xmalloc( 32768 );
while( pt->len ) {
int len = pt->len > 32768 ? 32768 : pt->len;
len = iobuf_read( pt->buf, buffer, len );
if( len == -1 ) {
rc = gpg_error_from_syserror ();
log_error ("problem reading source (%u bytes remaining)\n",
(unsigned)pt->len);
xfree( buffer );
goto leave;
}
if( mfx->md )
gcry_md_write ( mfx->md, buffer, len );
if( fp )
{
if(opt.max_output && (count+=len)>opt.max_output)
{
log_error ("error writing to `%s': %s\n",
fname,"exceeded --max-output limit\n");
rc = gpg_error (GPG_ERR_TOO_LARGE);
xfree( buffer );
goto leave;
}
else if( fwrite( buffer, 1, len, fp ) != len )
{
rc = gpg_error_from_syserror ();
log_error ("error writing to `%s': %s\n",
fname, strerror(errno) );
xfree( buffer );
goto leave;
}
}
pt->len -= len;
}
xfree( buffer );
}
}
else if( !clearsig ) {
if( convert ) { /* text mode */
while( (c = iobuf_get(pt->buf)) != -1 ) {
if( mfx->md )
gcry_md_putc (mfx->md, c );
#ifndef HAVE_DOSISH_SYSTEM
if( convert && c == '\r' )
continue; /* fixme: this hack might be too simple */
#endif
if( fp )
{
if(opt.max_output && (++count)>opt.max_output)
{
log_error("Error writing to `%s': %s\n",
fname,"exceeded --max-output limit\n");
rc = gpg_error (GPG_ERR_TOO_LARGE);
goto leave;
}
else if( putc( c, fp ) == EOF )
{
if ( ferror (fp ) )
rc = gpg_error_from_syserror ();
else
rc = gpg_error (GPG_ERR_EOF);
log_error("error writing to `%s': %s\n",
fname, strerror(errno) );
goto leave;
}
}
}
}
else { /* binary mode */
byte *buffer = xmalloc( 32768 );
int eof_seen = 0;
while ( !eof_seen ) {
/* Why do we check for len < 32768:
* If we won't, we would practically read 2 EOFs but
* the first one has already popped the block_filter
* off and therefore we don't catch the boundary.
* So, always assume EOF if iobuf_read returns less bytes
* then requested */
int len = iobuf_read( pt->buf, buffer, 32768 );
if( len == -1 )
break;
if( len < 32768 )
eof_seen = 1;
if( mfx->md )
gcry_md_write ( mfx->md, buffer, len );
if( fp )
{
if(opt.max_output && (count+=len)>opt.max_output)
{
log_error("error writing to `%s': %s\n",
fname,"exceeded --max-output limit\n");
rc = gpg_error (GPG_ERR_TOO_LARGE);
xfree( buffer );
goto leave;
}
else if( fwrite( buffer, 1, len, fp ) != len ) {
rc = (errno? gpg_error_from_syserror ()
: gpg_error (GPG_ERR_INTERNAL));
log_error ("error writing to `%s': %s\n",
fname, strerror(errno) );
xfree( buffer );
goto leave;
}
}
}
xfree( buffer );
}
pt->buf = NULL;
}
else { /* clear text signature - don't hash the last cr,lf */
int state = 0;
while( (c = iobuf_get(pt->buf)) != -1 ) {
if( fp )
{
if(opt.max_output && (++count)>opt.max_output)
{
log_error ("error writing to `%s': %s\n",
fname,"exceeded --max-output limit\n");
rc = gpg_error (GPG_ERR_TOO_LARGE);
goto leave;
}
else if( putc( c, fp ) == EOF )
{
rc = (errno? gpg_error_from_syserror ()
: gpg_error (GPG_ERR_INTERNAL));
log_error ("error writing to `%s': %s\n",
fname, strerror(errno) );
goto leave;
}
}
if( !mfx->md )
continue;
if( state == 2 ) {
gcry_md_putc (mfx->md, '\r' );
gcry_md_putc (mfx->md, '\n' );
state = 0;
}
if( !state ) {
if( c == '\r' )
state = 1;
else if( c == '\n' )
state = 2;
else
gcry_md_putc(mfx->md, c );
}
else if( state == 1 ) {
if( c == '\n' )
state = 2;
else {
gcry_md_putc(mfx->md, '\r' );
if( c == '\r' )
state = 1;
else {
state = 0;
gcry_md_putc(mfx->md, c );
}
}
}
}
pt->buf = NULL;
}
if( fp && fp != stdout && fclose(fp) ) {
rc = (errno? gpg_error_from_syserror ()
: gpg_error (GPG_ERR_INTERNAL));
log_error ("error closing `%s': %s\n", fname, strerror(errno) );
fp = NULL;
goto leave;
}
fp = NULL;
leave:
/* Make sure that stdout gets flushed after the plaintext has
been handled. This is for extra security as we do a
flush anyway before checking the signature. */
if (fflush (stdout))
{
/* We need to check the return code to detect errors like disk
full for short plaintexts. See bug#1207. Checking return
values is a good idea in any case. */
if (!rc)
rc = gpg_error_from_syserror ();
log_error ("error flushing `%s': %s\n", "[stdout]", strerror (errno) );
}
if( fp && fp != stdout )
fclose (fp);
xfree(fname);
return rc;
}
static void
do_hash( gcry_md_hd_t md, gcry_md_hd_t md2, IOBUF fp, int textmode )
{
text_filter_context_t tfx;
int c;
if( textmode ) {
memset( &tfx, 0, sizeof tfx);
iobuf_push_filter( fp, text_filter, &tfx );
}
if( md2 ) { /* work around a strange behaviour in pgp2 */
/* It seems that at least PGP5 converts a single CR to a CR,LF too */
int lc = -1;
while( (c = iobuf_get(fp)) != -1 ) {
if( c == '\n' && lc == '\r' )
gcry_md_putc (md2, c);
else if( c == '\n' ) {
gcry_md_putc (md2, '\r');
gcry_md_putc (md2, c);
}
else if( c != '\n' && lc == '\r' ) {
gcry_md_putc (md2, '\n');
gcry_md_putc (md2, c);
}
else
gcry_md_putc (md2, c);
if( md )
gcry_md_putc (md, c );
lc = c;
}
}
else {
while( (c = iobuf_get(fp)) != -1 ) {
if( md )
gcry_md_putc (md, c );
}
}
}
/****************
* Ask for the detached datafile and calculate the digest from it.
* INFILE is the name of the input file.
*/
int
ask_for_detached_datafile (gcry_md_hd_t md, gcry_md_hd_t md2,
const char *inname, int textmode )
{
progress_filter_context_t *pfx;
char *answer = NULL;
IOBUF fp;
int rc = 0;
pfx = new_progress_context ();
fp = open_sigfile ( inname, pfx ); /* Open default file. */
if( !fp && !opt.batch ) {
int any=0;
tty_printf(_("Detached signature.\n"));
do {
char *name;
xfree(answer);
tty_enable_completion(NULL);
name = cpr_get("detached_signature.filename",
_("Please enter name of data file: "));
tty_disable_completion();
cpr_kill_prompt();
answer=make_filename(name,(void *)NULL);
xfree(name);
if( any && !*answer ) {
rc = gpg_error (GPG_ERR_GENERAL); /*G10ERR_READ_FILE*/
goto leave;
}
fp = iobuf_open(answer);
if (fp && is_secured_file (iobuf_get_fd (fp)))
{
iobuf_close (fp);
fp = NULL;
errno = EPERM;
}
if( !fp && errno == ENOENT ) {
tty_printf("No such file, try again or hit enter to quit.\n");
any++;
}
else if( !fp )
{
rc = gpg_error_from_syserror ();
log_error(_("can't open `%s': %s\n"), answer, strerror(errno));
goto leave;
}
} while( !fp );
}
if( !fp ) {
if( opt.verbose )
log_info(_("reading stdin ...\n"));
fp = iobuf_open( NULL );
assert(fp);
}
do_hash( md, md2, fp, textmode );
iobuf_close(fp);
leave:
xfree(answer);
release_progress_context (pfx);
return rc;
}
/****************
* Hash the given files and append the hash to hash context md.
* If FILES is NULL, hash stdin.
*/
int
hash_datafiles( gcry_md_hd_t md, gcry_md_hd_t md2, strlist_t files,
const char *sigfilename, int textmode )
{
progress_filter_context_t *pfx;
IOBUF fp;
strlist_t sl;
pfx = new_progress_context ();
if( !files ) {
/* Check whether we can open the signed material. We avoid
trying to open a file if run in batch mode. This assumed
data file for a sig file feature is just a convenience thing
for the command line and the user needs to read possible
warning messages. */
if (!opt.batch)
{
fp = open_sigfile( sigfilename, pfx );
if( fp )
{
do_hash( md, md2, fp, textmode );
iobuf_close(fp);
release_progress_context (pfx);
return 0;
}
}
log_error (_("no signed data\n"));
release_progress_context (pfx);
return gpg_error (GPG_ERR_NO_DATA);
}
for (sl=files; sl; sl = sl->next ) {
fp = iobuf_open( sl->d );
if (fp && is_secured_file (iobuf_get_fd (fp)))
{
iobuf_close (fp);
fp = NULL;
errno = EPERM;
}
if( !fp ) {
int rc = gpg_error_from_syserror ();
log_error(_("can't open signed data `%s'\n"),
print_fname_stdin(sl->d));
release_progress_context (pfx);
return rc;
}
handle_progress (pfx, fp, sl->d);
do_hash( md, md2, fp, textmode );
iobuf_close(fp);
}
release_progress_context (pfx);
return 0;
}
/* Hash the data from file descriptor DATA_FD and append the hash to hash
contexts MD and MD2. */
int
hash_datafile_by_fd ( gcry_md_hd_t md, gcry_md_hd_t md2, int data_fd,
int textmode )
{
progress_filter_context_t *pfx = new_progress_context ();
iobuf_t fp;
fp = iobuf_fdopen (data_fd, "rb");
if (fp && is_secured_file (data_fd))
{
iobuf_close (fp);
fp = NULL;
errno = EPERM;
}
if ( !fp )
{
int rc = gpg_error_from_syserror ();
log_error ( _("can't open signed data fd=%d: %s\n"),
data_fd, strerror (errno));
release_progress_context (pfx);
return rc;
}
handle_progress (pfx, fp, NULL);
do_hash ( md, md2, fp, textmode);
iobuf_close(fp);
release_progress_context (pfx);
return 0;
}
/* Set up a plaintext packet with the appropriate filename. If there
is a --set-filename, use it (it's already UTF8). If there is a
regular filename, UTF8-ize it if necessary. If there is no
filenames at all, set the field empty. */
PKT_plaintext *
setup_plaintext_name(const char *filename,IOBUF iobuf)
{
PKT_plaintext *pt;
if ((filename && !iobuf_is_pipe_filename (filename))
|| (opt.set_filename && !iobuf_is_pipe_filename (opt.set_filename)))
{
char *s;
if(opt.set_filename)
s=make_basename(opt.set_filename,iobuf_get_real_fname(iobuf));
else if(filename && !opt.flags.utf8_filename)
{
char *tmp=native_to_utf8(filename);
s=make_basename(tmp,iobuf_get_real_fname(iobuf));
xfree(tmp);
}
else
s=make_basename(filename,iobuf_get_real_fname(iobuf));
pt = xmalloc (sizeof *pt + strlen(s) - 1);
pt->namelen = strlen (s);
memcpy (pt->name, s, pt->namelen);
xfree (s);
}
else
{
/* no filename */
pt = xmalloc (sizeof *pt - 1);
pt->namelen = 0;
}
return pt;
}
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