mirror of
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417 lines
10 KiB
C
417 lines
10 KiB
C
/* mount.c - Mount a crypto container
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* Copyright (C) 2009 Free Software Foundation, Inc.
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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 "i18n.h"
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#include "mount.h"
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#include "keyblob.h"
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#include "backend.h"
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#include "utils.h"
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#include "call-gpg.h"
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#include "estream.h"
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#include "mountinfo.h"
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#include "runner.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 = ((packet[2] << 24) | (packet[3] << 16)
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| (packet[4] << 8) | packet[5]);
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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 || packet[25] != 0)
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{
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log_error ("meta data copies in `%s' are not supported\n", filename);
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return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
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}
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len = ((packet[20] << 24) | (packet[21] << 16)
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| (packet[22] << 8) | packet[23]);
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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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/* 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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static gpg_error_t
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read_keyblob (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, 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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/* Decrypt the keyblob (ENCKEYBLOB,ENCKEYBLOBLEN) and store the result at
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(R_KEYBLOB, R_KEYBLOBLEN). Returns 0 on success or an error code.
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On error R_KEYBLOB is set to NULL. */
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static gpg_error_t
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decrypt_keyblob (ctrl_t ctrl, const void *enckeyblob, size_t enckeybloblen,
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void **r_keyblob, size_t *r_keybloblen)
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{
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gpg_error_t err;
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/* FIXME: For now we only implement OpenPGP. */
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err = gpg_decrypt_blob (ctrl, enckeyblob, enckeybloblen,
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r_keyblob, r_keybloblen);
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return err;
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}
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static void
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dump_keyblob (tupledesc_t tuples)
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{
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size_t n;
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unsigned int tag;
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const void *value;
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log_info ("keyblob dump:\n");
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tag = KEYBLOB_TAG_BLOBVERSION;
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value = find_tuple (tuples, tag, &n);
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while (value)
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{
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log_info (" tag: %-5u len: %-2u value: ", tag, (unsigned int)n);
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if (tag == KEYBLOB_TAG_ENCKEY
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|| tag == KEYBLOB_TAG_MACKEY)
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log_printf ("[confidential]\n");
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else if (!n)
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log_printf ("[none]\n");
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else
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log_printhex ("", value, n);
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value = next_tuple (tuples, &tag, &n);
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}
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}
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/* Mount the container with name FILENAME at MOUNTPOINT. */
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gpg_error_t
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g13_mount_container (ctrl_t ctrl, const char *filename, const char *mountpoint)
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{
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gpg_error_t err;
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dotlock_t lock;
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void *enckeyblob = NULL;
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size_t enckeybloblen;
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void *keyblob = NULL;
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size_t keybloblen;
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tupledesc_t tuples = NULL;
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size_t n;
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const unsigned char *value;
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int conttype;
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unsigned int rid;
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char *mountpoint_buffer = NULL;
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/* A quick check to see whether the container exists. */
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if (access (filename, R_OK))
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return gpg_error_from_syserror ();
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if (!mountpoint)
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{
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mountpoint_buffer = xtrystrdup ("/tmp/g13-XXXXXX");
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if (!mountpoint_buffer)
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return gpg_error_from_syserror ();
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if (!mkdtemp (mountpoint_buffer))
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{
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err = gpg_error_from_syserror ();
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log_error (_("can't create directory `%s': %s\n"),
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"/tmp/g13-XXXXXX", gpg_strerror (err));
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xfree (mountpoint_buffer);
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return err;
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}
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mountpoint = mountpoint_buffer;
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}
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/* Try to take a lock. */
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lock = dotlock_create (filename, 0);
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if (!lock)
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{
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xfree (mountpoint_buffer);
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return gpg_error_from_syserror ();
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}
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if (dotlock_take (lock, 0))
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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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else
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err = 0;
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/* Check again that the file exists. */
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{
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struct stat sb;
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if (stat (filename, &sb))
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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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}
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/* Read the encrypted keyblob. */
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err = read_keyblob (filename, &enckeyblob, &enckeybloblen);
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if (err)
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goto leave;
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/* Decrypt that keyblob and store it in a tuple descriptor. */
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err = decrypt_keyblob (ctrl, enckeyblob, enckeybloblen,
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&keyblob, &keybloblen);
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if (err)
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goto leave;
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xfree (enckeyblob);
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enckeyblob = NULL;
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err = create_tupledesc (&tuples, keyblob, keybloblen);
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if (!err)
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keyblob = NULL;
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else
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{
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if (gpg_err_code (err) == GPG_ERR_NOT_SUPPORTED)
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log_error ("unknown keyblob version\n");
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goto leave;
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}
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if (opt.verbose)
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dump_keyblob (tuples);
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value = find_tuple (tuples, KEYBLOB_TAG_CONTTYPE, &n);
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if (!value || n != 2)
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conttype = 0;
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else
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conttype = (value[0] << 8 | value[1]);
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if (!be_is_supported_conttype (conttype))
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{
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log_error ("content type %d is not supported\n", conttype);
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err = gpg_error (GPG_ERR_NOT_SUPPORTED);
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goto leave;
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}
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err = be_mount_container (ctrl, conttype, filename, mountpoint, tuples, &rid);
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if (!err)
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{
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err = mountinfo_add_mount (filename, mountpoint, conttype, rid,
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!!mountpoint_buffer);
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/* Fixme: What shall we do if this fails? Add a provisional
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mountinfo entry first and remove it on error? */
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if (!err)
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{
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char *tmp = percent_plus_escape (mountpoint);
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if (!tmp)
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err = gpg_error_from_syserror ();
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else
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{
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g13_status (ctrl, STATUS_MOUNTPOINT, tmp, NULL);
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xfree (tmp);
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}
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}
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}
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leave:
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destroy_tupledesc (tuples);
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xfree (keyblob);
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xfree (enckeyblob);
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dotlock_destroy (lock);
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xfree (mountpoint_buffer);
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return err;
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}
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/* Unmount the container with name FILENAME or the one mounted at
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MOUNTPOINT. If both are given the FILENAME takes precedence. */
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gpg_error_t
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g13_umount_container (ctrl_t ctrl, const char *filename, const char *mountpoint)
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{
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gpg_error_t err;
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unsigned int rid;
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runner_t runner;
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(void)ctrl;
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if (!filename && !mountpoint)
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return gpg_error (GPG_ERR_ENOENT);
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err = mountinfo_find_mount (filename, mountpoint, &rid);
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if (err)
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return err;
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runner = runner_find_by_rid (rid);
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if (!runner)
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{
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log_error ("runner %u not found\n", rid);
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return gpg_error (GPG_ERR_NOT_FOUND);
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}
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runner_cancel (runner);
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runner_release (runner);
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return 0;
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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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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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