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gnupg/g10/openfile.c
Werner Koch 69384568f6 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>
2014-11-13 17:39:31 +01:00

519 lines
13 KiB
C

/* openfile.c
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2009,
* 2010 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 <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "gpg.h"
#include "util.h"
#include "ttyio.h"
#include "options.h"
#include "main.h"
#include "status.h"
#include "i18n.h"
#ifdef USE_ONLY_8DOT3
#define SKELEXT ".skl"
#else
#define SKELEXT EXTSEP_S "skel"
#endif
#ifdef HAVE_W32_SYSTEM
#define NAME_OF_DEV_NULL "nul"
#else
#define NAME_OF_DEV_NULL "/dev/null"
#endif
#if defined (HAVE_DRIVE_LETTERS) || defined (__riscos__)
#define CMP_FILENAME(a,b) ascii_strcasecmp( (a), (b) )
#else
#define CMP_FILENAME(a,b) strcmp( (a), (b) )
#endif
/* FIXME: Implement opt.interactive. */
/*
* Check whether FNAME exists and ask if it's okay to overwrite an
* existing one.
* Returns: True: it's okay to overwrite or the file does not exist
* False: Do not overwrite
*/
int
overwrite_filep( const char *fname )
{
if ( iobuf_is_pipe_filename (fname) )
return 1; /* Writing to stdout is always okay. */
if ( access( fname, F_OK ) )
return 1; /* Does not exist. */
if ( !compare_filenames (fname, NAME_OF_DEV_NULL) )
return 1; /* Does not do any harm. */
if (opt.answer_yes)
return 1;
if (opt.answer_no || opt.batch)
return 0; /* Do not overwrite. */
tty_printf (_("File '%s' exists. "), fname);
if (cpr_enabled ())
tty_printf ("\n");
if (cpr_get_answer_is_yes ("openfile.overwrite.okay",
_("Overwrite? (y/N) ")) )
return 1;
return 0;
}
/*
* Strip known extensions from iname and return a newly allocated
* filename. Return NULL if we can't do that.
*/
char *
make_outfile_name (const char *iname)
{
size_t n;
if (iobuf_is_pipe_filename (iname))
return xstrdup ("-");
n = strlen (iname);
if (n > 4 && (!CMP_FILENAME(iname+n-4, EXTSEP_S GPGEXT_GPG)
|| !CMP_FILENAME(iname+n-4, EXTSEP_S "pgp")
|| !CMP_FILENAME(iname+n-4, EXTSEP_S "sig")
|| !CMP_FILENAME(iname+n-4, EXTSEP_S "asc")))
{
char *buf = xstrdup (iname);
buf[n-4] = 0;
return buf;
}
else if (n > 5 && !CMP_FILENAME(iname+n-5, EXTSEP_S "sign"))
{
char *buf = xstrdup (iname);
buf[n-5] = 0;
return buf;
}
log_info (_("%s: unknown suffix\n"), iname);
return NULL;
}
/* Ask for an output filename; use the given one as default. Return
NULL if no file has been given or if it is not possible to ask the
user. NAME is the template len which might conatin enbedded Nuls.
NAMELEN is its actual length.
*/
char *
ask_outfile_name( const char *name, size_t namelen )
{
size_t n;
const char *s;
char *prompt;
char *fname;
char *defname;
if ( opt.batch )
return NULL;
defname = name && namelen? make_printable_string (name, namelen, 0) : NULL;
s = _("Enter new filename");
n = strlen(s) + (defname?strlen (defname):0) + 10;
prompt = xmalloc (n);
if (defname)
snprintf (prompt, n-1, "%s [%s]: ", s, defname );
else
snprintf (prompt, n-1, "%s: ", s );
tty_enable_completion(NULL);
fname = cpr_get ("openfile.askoutname", prompt );
cpr_kill_prompt ();
tty_disable_completion ();
xfree (prompt);
if ( !*fname )
{
xfree (fname);
fname = defname;
defname = NULL;
}
xfree (defname);
if (fname)
trim_spaces (fname);
return fname;
}
/*
* Make an output filename for the inputfile INAME.
* Returns an IOBUF and an errorcode
* Mode 0 = use ".gpg"
* 1 = use ".asc"
* 2 = use ".sig"
* 3 = use ".rev"
*
* If INP_FD is not -1 the function simply creates an IOBUF for that
* file descriptor and ignore INAME and MODE. Note that INP_FD won't
* be closed if the returned IOBUF is closed. With RESTRICTEDPERM a
* file will be created with mode 700 if possible.
*/
int
open_outfile (int inp_fd, const char *iname, int mode, int restrictedperm,
iobuf_t *a)
{
int rc = 0;
*a = NULL;
if (inp_fd != -1)
{
char xname[64];
*a = iobuf_fdopen_nc (inp_fd, "wb");
if (!*a)
{
rc = gpg_error_from_syserror ();
snprintf (xname, sizeof xname, "[fd %d]", inp_fd);
log_error (_("can't open '%s': %s\n"), xname, gpg_strerror (rc));
}
else if (opt.verbose)
{
snprintf (xname, sizeof xname, "[fd %d]", inp_fd);
log_info (_("writing to '%s'\n"), xname);
}
}
else if (iobuf_is_pipe_filename (iname) && !opt.outfile)
{
*a = iobuf_create (NULL, 0);
if ( !*a )
{
rc = gpg_error_from_syserror ();
log_error (_("can't open '%s': %s\n"), "[stdout]", strerror(errno) );
}
else if ( opt.verbose )
log_info (_("writing to stdout\n"));
}
else
{
char *buf = NULL;
const char *name;
if (opt.dry_run)
name = NAME_OF_DEV_NULL;
else if (opt.outfile)
name = opt.outfile;
else
{
#ifdef USE_ONLY_8DOT3
if (opt.mangle_dos_filenames)
{
/* It is quite common for DOS systems to have only one
dot in a filename. If we have something like this,
we simple replace the suffix except in cases where
the suffix is larger than 3 characters and not the
same as the new one. We don't map the filenames to
8.3 because this is a duty of the file system. */
char *dot;
const char *newsfx;
newsfx = (mode==1 ? ".asc" :
mode==2 ? ".sig" :
mode==3 ? ".rev" : ".gpg");
buf = xmalloc (strlen(iname)+4+1);
strcpy (buf, iname);
dot = strchr (buf, '.' );
if ( dot && dot > buf && dot[1] && strlen(dot) <= 4
&& CMP_FILENAME (newsfx, dot) )
strcpy (dot, newsfx);
else if (dot && !dot[1]) /* Do not duplicate a dot. */
strcpy (dot, newsfx+1);
else
strcat (buf, newsfx);
}
if (!buf)
#endif /* USE_ONLY_8DOT3 */
{
buf = xstrconcat (iname,
(mode==1 ? EXTSEP_S "asc" :
mode==2 ? EXTSEP_S "sig" :
mode==3 ? EXTSEP_S "rev" :
/* */ EXTSEP_S GPGEXT_GPG),
NULL);
}
name = buf;
}
rc = 0;
while ( !overwrite_filep (name) )
{
char *tmp = ask_outfile_name (NULL, 0);
if ( !tmp || !*tmp )
{
xfree (tmp);
rc = gpg_error (GPG_ERR_EEXIST);
break;
}
xfree (buf);
name = buf = tmp;
}
if ( !rc )
{
if (is_secured_filename (name) )
{
*a = NULL;
gpg_err_set_errno (EPERM);
}
else
*a = iobuf_create (name, restrictedperm);
if (!*a)
{
rc = gpg_error_from_syserror ();
log_error(_("can't create '%s': %s\n"), name, strerror(errno) );
}
else if( opt.verbose )
log_info (_("writing to '%s'\n"), name );
}
xfree(buf);
}
if (*a)
iobuf_ioctl (*a, IOBUF_IOCTL_NO_CACHE, 1, NULL);
return rc;
}
/* Find a matching data file for the signature file SIGFILENAME and
return it as a malloced string. If no matching data file is found,
return NULL. */
char *
get_matching_datafile (const char *sigfilename)
{
char *fname = NULL;
size_t len;
if (iobuf_is_pipe_filename (sigfilename))
return NULL;
len = strlen (sigfilename);
if (len > 4
&& (!strcmp (sigfilename + len - 4, EXTSEP_S "sig")
|| (len > 5 && !strcmp(sigfilename + len - 5, EXTSEP_S "sign"))
|| !strcmp(sigfilename + len - 4, EXTSEP_S "asc")))
{
fname = xstrdup (sigfilename);
fname[len-(fname[len-1]=='n'?5:4)] = 0 ;
if (access (fname, R_OK ))
{
/* Not found or other error. */
xfree (fname);
fname = NULL;
}
}
return fname;
}
/*
* Try to open a file without the extension ".sig" or ".asc"
* Return NULL if such a file is not available.
*/
iobuf_t
open_sigfile (const char *sigfilename, progress_filter_context_t *pfx)
{
iobuf_t a = NULL;
char *buf;
buf = get_matching_datafile (sigfilename);
if (buf)
{
a = iobuf_open (buf);
if (a && is_secured_file (iobuf_get_fd (a)))
{
iobuf_close (a);
a = NULL;
gpg_err_set_errno (EPERM);
}
if (a)
log_info (_("assuming signed data in '%s'\n"), buf);
if (a && pfx)
handle_progress (pfx, a, buf);
xfree (buf);
}
return a;
}
/****************
* Copy the option file skeleton to the given directory.
*/
static void
copy_options_file (const char *destdir)
{
const char *datadir = gnupg_datadir ();
char *fname;
FILE *src, *dst;
int linefeeds=0;
int c;
mode_t oldmask;
int esc = 0;
int any_option = 0;
if (opt.dry_run)
return;
fname = xmalloc (strlen(datadir) + strlen(destdir) + 15);
strcpy (stpcpy(fname, datadir), DIRSEP_S "gpg-conf" SKELEXT);
src = fopen (fname, "r");
if (src && is_secured_file (fileno (src)))
{
fclose (src);
src = NULL;
gpg_err_set_errno (EPERM);
}
if (!src)
{
log_info (_("can't open '%s': %s\n"), fname, strerror(errno));
xfree(fname);
return;
}
strcpy (stpcpy (fname, destdir), DIRSEP_S GPGEXT_GPG EXTSEP_S "conf");
oldmask = umask (077);
if (is_secured_filename (fname))
{
dst = NULL;
gpg_err_set_errno (EPERM);
}
else
dst = fopen( fname, "w" );
umask (oldmask);
if (!dst)
{
log_info (_("can't create '%s': %s\n"), fname, strerror(errno) );
fclose (src);
xfree (fname);
return;
}
while ((c = getc (src)) != EOF)
{
if (linefeeds < 3)
{
if (c == '\n')
linefeeds++;
}
else
{
putc (c, dst);
if (c== '\n')
esc = 1;
else if (esc == 1)
{
if (c == ' ' || c == '\t')
;
else if (c == '#')
esc = 2;
else
any_option = 1;
}
}
}
fclose (dst);
fclose (src);
log_info (_("new configuration file '%s' created\n"), fname);
if (any_option)
log_info (_("WARNING: options in '%s'"
" are not yet active during this run\n"),
fname);
xfree (fname);
}
void
try_make_homedir (const char *fname)
{
const char *defhome = standard_homedir ();
/* Create the directory only if the supplied directory name is the
same as the default one. This way we avoid to create arbitrary
directories when a non-default home directory is used. To cope
with HOME, we do compare only the suffix if we see that the
default homedir does start with a tilde. */
if ( opt.dry_run || opt.no_homedir_creation )
return;
if (
#ifdef HAVE_W32_SYSTEM
( !compare_filenames (fname, defhome) )
#else
( *defhome == '~'
&& (strlen(fname) >= strlen (defhome+1)
&& !strcmp(fname+strlen(fname)-strlen(defhome+1), defhome+1 ) ))
|| (*defhome != '~' && !compare_filenames( fname, defhome ) )
#endif
)
{
if (gnupg_mkdir (fname, "-rwx"))
log_fatal ( _("can't create directory '%s': %s\n"),
fname, strerror(errno) );
else if (!opt.quiet )
log_info ( _("directory '%s' created\n"), fname );
copy_options_file( fname );
}
}
/* Get and if needed create a string with the directory used to store
openpgp revocations. */
char *
get_openpgp_revocdir (const char *home)
{
char *fname;
struct stat statbuf;
fname = make_filename (home, GNUPG_OPENPGP_REVOC_DIR, NULL);
if (stat (fname, &statbuf) && errno == ENOENT)
{
if (gnupg_mkdir (fname, "-rwx"))
log_error (_("can't create directory '%s': %s\n"),
fname, strerror (errno) );
else if (!opt.quiet)
log_info (_("directory '%s' created\n"), fname);
}
return fname;
}