path: root/lib/libalpm/signing.c

/*
 *  signing.c
 *
 *  Copyright (c) 2008-2011 Pacman Development Team <pacman-dev@archlinux.org>
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <locale.h> /* setlocale() */
#include <gpgme.h>

/* libalpm */
#include "signing.h"
#include "package.h"
#include "util.h"
#include "log.h"
#include "alpm.h"

#define CHECK_ERR(void) do { \
    if(err != GPG_ERR_NO_ERROR) { goto error; } \
  } while(0)

static int gpgme_init(void)
{
  static int init = 0;
  const char *version;
  gpgme_error_t err;
  gpgme_engine_info_t enginfo;

  ALPM_LOG_FUNC;

  if(init) {
    /* we already successfully initialized the library */
    return 0;
  }

  if(!alpm_option_get_signaturedir()) {
    RET_ERR(PM_ERR_SIG_MISSINGDIR, 1);
  }

  /* calling gpgme_check_version() returns the current version and runs
   * some internal library setup code */
  version = gpgme_check_version(NULL);
  _alpm_log(PM_LOG_DEBUG, "GPGME version: %s\n", version);
  gpgme_set_locale(NULL, LC_CTYPE, setlocale(LC_CTYPE, NULL));
#ifdef LC_MESSAGES
  gpgme_set_locale(NULL, LC_MESSAGES, setlocale(LC_MESSAGES, NULL));
#endif
  /* NOTE:
   * The GPGME library installs a SIGPIPE signal handler automatically if
   * the default signal hander is in use. The only time we set a handler
   * for SIGPIPE is in dload.c, and we reset it when we are done. Given that
   * we do this, we can let GPGME do its automagic. However, if we install
   * a library-wide SIGPIPE handler, we will have to be careful.
   */

  /* check for OpenPGP support (should be a no-brainer, but be safe) */
  err = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
  CHECK_ERR();

  /* set and check engine information */
  err = gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP, NULL,
      alpm_option_get_signaturedir());
  CHECK_ERR();
  err = gpgme_get_engine_info(&enginfo);
  CHECK_ERR();
  _alpm_log(PM_LOG_DEBUG, "GPGME engine info: file=%s, home=%s\n",
      enginfo->file_name, enginfo->home_dir);

  init = 1;
  return 0;

error:
  _alpm_log(PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
  RET_ERR(PM_ERR_GPGME, 1);
}

/**
 * Check the PGP package signature for the given file.
 * @param path the full path to a file
 * @param sig PGP signature data in raw form (already decoded)
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
{
  int ret = 0;
  gpgme_error_t err;
  gpgme_ctx_t ctx;
  gpgme_data_t filedata, sigdata;
  gpgme_verify_result_t result;
  gpgme_signature_t gpgsig;
  FILE *file = NULL, *sigfile = NULL;

  ALPM_LOG_FUNC;

  if(!sig || !sig->rawdata) {
     RET_ERR(PM_ERR_SIG_UNKNOWN, -1);
  }
  if(!path || access(path, R_OK) != 0) {
    RET_ERR(PM_ERR_NOT_A_FILE, -1);
  }
  if(gpgme_init()) {
    /* pm_errno was set in gpgme_init() */
    return -1;
  }

  _alpm_log(PM_LOG_DEBUG, "checking signature for %s\n", path);

  memset(&ctx, 0, sizeof(ctx));
  memset(&sigdata, 0, sizeof(sigdata));
  memset(&filedata, 0, sizeof(filedata));

  err = gpgme_new(&ctx);
  CHECK_ERR();

  /* create our necessary data objects to verify the signature */
  file = fopen(path, "rb");
  if(file == NULL) {
    pm_errno = PM_ERR_NOT_A_FILE;
    ret = -1;
    goto error;
  }
  err = gpgme_data_new_from_stream(&filedata, file);
  CHECK_ERR();

  /* next create data object for the signature */
  err = gpgme_data_new_from_mem(&sigdata, (char*)sig->rawdata, sig->rawlen, 0);
  CHECK_ERR();

  /* here's where the magic happens */
  err = gpgme_op_verify(ctx, sigdata, filedata, NULL);
  CHECK_ERR();
  result = gpgme_op_verify_result(ctx);
  gpgsig = result->signatures;
  if (!gpgsig || gpgsig->next) {
    _alpm_log(PM_LOG_ERROR, _("Unexpected number of signatures\n"));
    ret = -1;
    goto error;
  }
  _alpm_log(PM_LOG_DEBUG, "summary=%x\n", gpgsig->summary);
  _alpm_log(PM_LOG_DEBUG, "fpr=%s\n", gpgsig->fpr);
  _alpm_log(PM_LOG_DEBUG, "status=%d\n", gpgsig->status);
  _alpm_log(PM_LOG_DEBUG, "timestamp=%lu\n", gpgsig->timestamp);
  _alpm_log(PM_LOG_DEBUG, "wrong_key_usage=%u\n", gpgsig->wrong_key_usage);
  _alpm_log(PM_LOG_DEBUG, "pka_trust=%u\n", gpgsig->pka_trust);
  _alpm_log(PM_LOG_DEBUG, "chain_model=%u\n", gpgsig->chain_model);
  _alpm_log(PM_LOG_DEBUG, "validity=%d\n", gpgsig->validity);
  _alpm_log(PM_LOG_DEBUG, "validity_reason=%d\n", gpgsig->validity_reason);
  _alpm_log(PM_LOG_DEBUG, "key=%d\n", gpgsig->pubkey_algo);
  _alpm_log(PM_LOG_DEBUG, "hash=%d\n", gpgsig->hash_algo);

  if(gpgsig->summary & GPGME_SIGSUM_VALID) {
    /* good signature, continue */
    _alpm_log(PM_LOG_DEBUG, _("File %s has a valid signature.\n"),
        path);
  } else if(gpgsig->summary & GPGME_SIGSUM_GREEN) {
    /* 'green' signature, not sure what to do here */
    _alpm_log(PM_LOG_WARNING, _("File %s has a green signature.\n"),
        path);
  } else if(gpgsig->summary & GPGME_SIGSUM_KEY_MISSING) {
    pm_errno = PM_ERR_SIG_UNKNOWN;
    _alpm_log(PM_LOG_WARNING, _("File %s has a signature from an unknown key.\n"),
        path);
    ret = -1;
  } else {
    /* we'll capture everything else here */
    pm_errno = PM_ERR_SIG_INVALID;
    _alpm_log(PM_LOG_ERROR, _("File %s has an invalid signature.\n"),
        path);
    ret = 1;
  }

error:
  gpgme_data_release(sigdata);
  gpgme_data_release(filedata);
  gpgme_release(ctx);
  if(sigfile) {
    fclose(sigfile);
  }
  if(file) {
    fclose(file);
  }
  if(err != GPG_ERR_NO_ERROR) {
    _alpm_log(PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
    RET_ERR(PM_ERR_GPGME, -1);
  }
  return ret;
}

/**
 * Load the signature from the given path into the provided struct.
 * @param sigfile the signature to attempt to load
 * @param pgpsig the struct to place the data in
 *
 * @return 0 on success, 1 on file not found, -1 on error
 */
int _alpm_load_signature(const char *sigfile, pmpgpsig_t *pgpsig) {
  struct stat st;

  if(access(sigfile, R_OK) == 0 && stat(sigfile, &st) == 0) {
    FILE *f;
    size_t bytes_read;

    if(st.st_size > 4096) {
      return -1;
    }

    if((f = fopen(sigfile, "rb")) == NULL) {
      return -1;
    }
    CALLOC(pgpsig->rawdata, st.st_size, sizeof(unsigned char),
        RET_ERR(PM_ERR_MEMORY, -1));
    bytes_read = fread(pgpsig->rawdata, sizeof(char), st.st_size, f);
    if(bytes_read == (size_t)st.st_size) {
      pgpsig->rawlen = bytes_read;
      _alpm_log(PM_LOG_DEBUG, "loaded gpg signature file, location %s\n",
          sigfile);
    } else {
      _alpm_log(PM_LOG_WARNING, _("Failed reading PGP signature file %s"),
          sigfile);
      FREE(pgpsig->rawdata);
      return -1;
    }

    fclose(f);
  } else {
    _alpm_log(PM_LOG_DEBUG, "signature file %s not found\n", sigfile);
    /* not fatal...we return a different error code here */
    return 1;
  }

  return 0;
}

/**
 * Check the PGP package signature for the given package file.
 * @param pkg the package to check
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int SYMEXPORT alpm_pkg_check_pgp_signature(pmpkg_t *pkg)
{
  ALPM_LOG_FUNC;
  ASSERT(pkg != NULL, return 0);

  return _alpm_gpgme_checksig(alpm_pkg_get_filename(pkg),
      alpm_pkg_get_pgpsig(pkg));
}

/**
 * Check the PGP package signature for the given database.
 * @param db the database to check
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int SYMEXPORT alpm_db_check_pgp_signature(pmdb_t *db)
{
  ALPM_LOG_FUNC;
  ASSERT(db != NULL, return(0));

  return _alpm_gpgme_checksig(_alpm_db_path(db),
      _alpm_db_pgpsig(db));
}


/* vim: set ts=2 sw=2 noet: */