diff options
Diffstat (limited to 'g13/mount.c')
| -rw-r--r-- | g13/mount.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/g13/mount.c b/g13/mount.c new file mode 100644 index 000000000..85851e9a8 --- /dev/null +++ b/g13/mount.c @@ -0,0 +1,303 @@ +/* mount.c - Mount a crypto container + * Copyright (C) 2009 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 <unistd.h> +#include <sys/stat.h> +#include <assert.h> + +#include "g13.h" +#include "i18n.h" +#include "mount.h" + +#include "keyblob.h" +#include "backend.h" +#include "utils.h" +#include "call-gpg.h" +#include "estream.h" + + +/* Parse the header prefix and return the length of the entire header. */ +static gpg_error_t +parse_header (const char *filename, + const unsigned char *packet, size_t packetlen, + size_t *r_headerlen) +{ + unsigned int len; + + if (packetlen != 32) + return gpg_error (GPG_ERR_BUG); + + len = ((packet[2] << 24) | (packet[3] << 16) + | (packet[4] << 8) | packet[5]); + if (packet[0] != (0xc0|61) || len < 26 + || memcmp (packet+6, "GnuPG/G13", 10)) + { + log_error ("file `%s' is not valid container\n", filename); + return gpg_error (GPG_ERR_INV_OBJ); + } + if (packet[16] != 1) + { + log_error ("unknown version %u of container `%s'\n", + (unsigned int)packet[16], filename); + return gpg_error (GPG_ERR_INV_OBJ); + } + if (packet[17] || packet[18] + || packet[26] || packet[27] || packet[28] || packet[29] + || packet[30] || packet[31]) + log_info ("WARNING: unknown meta information in `%s'\n", filename); + if (packet[19]) + log_info ("WARNING: OS flag is not supported in `%s'\n", filename); + if (packet[24] != 1 || packet[25] != 0) + { + log_error ("meta data copies in `%s' are not supported\n", filename); + return gpg_error (GPG_ERR_NOT_IMPLEMENTED); + } + + len = ((packet[20] << 24) | (packet[21] << 16) + | (packet[22] << 8) | packet[23]); + + /* Do a basic sanity check on the length. */ + if (len < 32 || len > 1024*1024) + { + log_error ("bad length given in container `%s'\n", filename); + return gpg_error (GPG_ERR_INV_OBJ); + } + + *r_headerlen = len; + return 0; +} + + + +/* Read the keyblob at FILENAME. The caller should have acquired a + lockfile and checked that the file exists. */ +static gpg_error_t +read_keyblob (const char *filename, + void **r_enckeyblob, size_t *r_enckeybloblen) +{ + gpg_error_t err; + estream_t fp; + unsigned char packet[32]; + size_t headerlen, msglen; + void *msg = NULL; + + *r_enckeyblob = NULL; + *r_enckeybloblen = 0; + + fp = es_fopen (filename, "rb"); + if (!fp) + { + err = gpg_error_from_syserror (); + log_error ("error reading `%s': %s\n", + filename, gpg_strerror (err)); + return err; + } + + /* Read the header. It is defined as 32 bytes thus we read it in one go. */ + if (es_fread (packet, 32, 1, fp) != 1) + { + err = gpg_error_from_syserror (); + log_error ("error reading the header of `%s': %s\n", + filename, gpg_strerror (err)); + goto leave; + } + + err = parse_header (filename, packet, 32, &headerlen); + if (err) + goto leave; + + if (opt.verbose) + log_info ("header length of `%s' is %zu\n", filename, headerlen); + + /* Read everything including the padding. We should eventually do a + regular OpenPGP parsing to detect the padding packet and pass + only the actual used OpenPGP data to the engine. This is in + particular required when supporting CMS which will be + encapsulated in an OpenPGP packet. */ + assert (headerlen >= 32); + msglen = headerlen - 32; + if (!msglen) + { + err = gpg_error (GPG_ERR_NO_DATA); + goto leave; + } + msg = xtrymalloc (msglen); + if (!msglen) + { + err = gpg_error_from_syserror (); + goto leave; + } + if (es_fread (msg, msglen, 1, fp) != 1) + { + err = gpg_error_from_syserror (); + log_error ("error reading keyblob of `%s': %s\n", + filename, gpg_strerror (err)); + goto leave; + } + + *r_enckeyblob = msg; + msg = NULL; + *r_enckeybloblen = msglen; + + leave: + xfree (msg); + es_fclose (fp); + + return err; +} + + + + +/* Decrypt the keyblob (ENCKEYBLOB,ENCKEYBLOBLEN) and store the result at + (R_KEYBLOB, R_KEYBLOBLEN). Returns 0 on success or an error code. + On error R_KEYBLOB is set to NULL. */ +static gpg_error_t +decrypt_keyblob (ctrl_t ctrl, const void *enckeyblob, size_t enckeybloblen, + void **r_keyblob, size_t *r_keybloblen) +{ + gpg_error_t err; + + /* FIXME: For now we only implement OpenPGP. */ + err = gpg_decrypt_blob (ctrl, enckeyblob, enckeybloblen, + r_keyblob, r_keybloblen); + + return err; +} + + +static void +dump_keyblob (tupledesc_t tuples) +{ + size_t n; + unsigned int tag; + const void *value; + + log_info ("keyblob dump:\n"); + tag = KEYBLOB_TAG_BLOBVERSION; + value = find_tuple (tuples, tag, &n); + while (value) + { + log_info (" tag: %-5u len: %-2u value: ", tag, (unsigned int)n); + if (tag == KEYBLOB_TAG_ENCKEY + || tag == KEYBLOB_TAG_MACKEY) + log_printf ("[confidential]\n"); + else if (!n) + log_printf ("[none]\n"); + else + log_printhex ("", value, n); + value = next_tuple (tuples, &tag, &n); + } +} + + + +/* Mount the container with name FILENAME at MOUNTPOINT. */ +gpg_error_t +g13_mount_container (ctrl_t ctrl, const char *filename, const char *mountpoint) +{ + gpg_error_t err; + dotlock_t lock; + void *enckeyblob = NULL; + size_t enckeybloblen; + void *keyblob = NULL; + size_t keybloblen; + tupledesc_t tuples = NULL; + size_t n; + const unsigned char *value; + int conttype; + + /* A quick check to see whether the container exists. */ + if (access (filename, R_OK)) + return gpg_error_from_syserror (); + + /* Try to take a lock. */ + lock = create_dotlock (filename); + if (!lock) + return gpg_error_from_syserror (); + + if (make_dotlock (lock, 0)) + { + err = gpg_error_from_syserror (); + goto leave; + } + else + err = 0; + + /* Check again that the file exists. */ + { + struct stat sb; + + if (stat (filename, &sb)) + { + err = gpg_error_from_syserror (); + goto leave; + } + } + + /* Read the encrypted keyblob. */ + err = read_keyblob (filename, &enckeyblob, &enckeybloblen); + if (err) + goto leave; + + /* Decrypt that keyblob and store it in a tuple descriptor. */ + err = decrypt_keyblob (ctrl, enckeyblob, enckeybloblen, + &keyblob, &keybloblen); + if (err) + goto leave; + xfree (enckeyblob); + enckeyblob = NULL; + + err = create_tupledesc (&tuples, keyblob, keybloblen); + if (!err) + keyblob = NULL; + else + { + if (gpg_err_code (err) == GPG_ERR_NOT_SUPPORTED) + log_error ("unknown keyblob version\n"); + goto leave; + } + if (opt.verbose) + dump_keyblob (tuples); + + value = find_tuple (tuples, KEYBLOB_TAG_CONTTYPE, &n); + if (!value || n != 2) + conttype = 0; + else + conttype = (value[0] << 8 | value[1]); + if (!be_is_supported_conttype (conttype)) + { + log_error ("content type %d is not supported\n", conttype); + err = gpg_error (GPG_ERR_NOT_SUPPORTED); + goto leave; + } + err = be_mount_container (ctrl, conttype, filename, mountpoint, tuples); + + leave: + destroy_tupledesc (tuples); + xfree (keyblob); + xfree (enckeyblob); + destroy_dotlock (lock); + return err; +} |