mirror of
git://git.gnupg.org/gnupg.git
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208 lines
5.3 KiB
C
208 lines
5.3 KiB
C
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/* keyblob.c - Keyblob parser and builder.
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* Copyright (C) 2009 Free Software Foundation, Inc.
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* Copyright (C) 2015-2016 Werner Koch
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include "g13.h"
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#include "mount.h"
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#include "keyblob.h"
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#include "../common/sysutils.h"
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#include "host2net.h"
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/* Parse the header prefix and return the length of the entire header. */
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static gpg_error_t
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parse_header (const char *filename,
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const unsigned char *packet, size_t packetlen,
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size_t *r_headerlen)
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{
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unsigned int len;
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if (packetlen != 32)
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return gpg_error (GPG_ERR_BUG);
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len = buf32_to_uint (packet+2);
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if (packet[0] != (0xc0|61) || len < 26
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|| memcmp (packet+6, "GnuPG/G13", 10))
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{
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log_error ("file '%s' is not valid container\n", filename);
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return gpg_error (GPG_ERR_INV_OBJ);
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}
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if (packet[16] != 1)
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{
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log_error ("unknown version %u of container '%s'\n",
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(unsigned int)packet[16], filename);
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return gpg_error (GPG_ERR_INV_OBJ);
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}
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if (packet[17] || packet[18]
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|| packet[26] || packet[27] || packet[28] || packet[29]
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|| packet[30] || packet[31])
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log_info ("WARNING: unknown meta information in '%s'\n", filename);
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if (packet[19])
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log_info ("WARNING: OS flag is not supported in '%s'\n", filename);
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if (packet[24] > 1 )
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log_info ("Note: meta data copies in '%s' are ignored\n", filename);
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len = buf32_to_uint (packet+20);
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/* Do a basic sanity check on the length. */
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if (len < 32 || len > 1024*1024)
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{
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log_error ("bad length given in container '%s'\n", filename);
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return gpg_error (GPG_ERR_INV_OBJ);
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}
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*r_headerlen = len;
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return 0;
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}
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/* Read the prefix of the keyblob and do some basic parsing. On
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success returns an open estream file at R_FP and the length of the
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header at R_HEADERLEN. */
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static gpg_error_t
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read_keyblob_prefix (const char *filename, estream_t *r_fp, size_t *r_headerlen)
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{
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gpg_error_t err;
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estream_t fp;
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unsigned char packet[32];
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*r_fp = NULL;
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fp = es_fopen (filename, "rb");
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if (!fp)
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{
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err = gpg_error_from_syserror ();
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log_error ("error reading '%s': %s\n", filename, gpg_strerror (err));
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return err;
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}
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/* Read the header. It is defined as 32 bytes thus we read it in one go. */
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if (es_fread (packet, 32, 1, fp) != 1)
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{
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err = gpg_error_from_syserror ();
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log_error ("error reading the header of '%s': %s\n",
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filename, gpg_strerror (err));
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es_fclose (fp);
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return err;
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}
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err = parse_header (filename, packet, 32, r_headerlen);
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if (err)
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es_fclose (fp);
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else
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*r_fp = fp;
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return err;
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}
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/*
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* Test whether the container with name FILENAME is a suitable G13
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* container. This function may even be called on a mounted
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* container.
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*/
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gpg_error_t
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g13_is_container (ctrl_t ctrl, const char *filename)
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{
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gpg_error_t err;
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estream_t fp = NULL;
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size_t dummy;
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(void)ctrl;
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/* Read just the prefix of the header. */
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err = read_keyblob_prefix (filename, &fp, &dummy);
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if (!err)
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es_fclose (fp);
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return err;
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}
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/*
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* Read the keyblob at FILENAME. The caller should have acquired a
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* lockfile and checked that the file exists.
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*/
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gpg_error_t
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g13_keyblob_read (const char *filename,
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void **r_enckeyblob, size_t *r_enckeybloblen)
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{
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gpg_error_t err;
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estream_t fp = NULL;
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size_t headerlen = 0;
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size_t msglen;
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void *msg = NULL;
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*r_enckeyblob = NULL;
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*r_enckeybloblen = 0;
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err = read_keyblob_prefix (filename, &fp, &headerlen);
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if (err)
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goto leave;
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if (opt.verbose)
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log_info ("header length of '%s' is %zu\n", filename, headerlen);
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/* Read everything including the padding. We should eventually do a
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regular OpenPGP parsing to detect the padding packet and pass
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only the actual used OpenPGP data to the engine. This is in
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particular required when supporting CMS which will be
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encapsulated in an OpenPGP packet. */
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assert (headerlen >= 32);
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msglen = headerlen - 32;
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if (!msglen)
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{
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err = gpg_error (GPG_ERR_NO_DATA);
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goto leave;
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}
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msg = xtrymalloc (msglen);
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if (!msglen)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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if (es_fread (msg, msglen, 1, fp) != 1)
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{
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err = gpg_error_from_syserror ();
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log_error ("error reading keyblob of '%s': %s\n",
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filename, gpg_strerror (err));
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goto leave;
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}
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*r_enckeyblob = msg;
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msg = NULL;
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*r_enckeybloblen = msglen;
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leave:
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xfree (msg);
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es_fclose (fp);
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return err;
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}
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