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pacman/lib/libalpm/signing.c

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/*
* 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>
#if HAVE_LIBGPGME
#include <locale.h> /* setlocale() */
#include <gpgme.h>
#include "base64.h"
#endif
/* libalpm */
#include "signing.h"
#include "package.h"
#include "util.h"
#include "log.h"
#include "alpm.h"
#include "handle.h"
#if HAVE_LIBGPGME
#define CHECK_ERR(void) do { \
if(gpg_err_code(err) != GPG_ERR_NO_ERROR) { goto error; } \
} while(0)
static const char *string_validity(gpgme_validity_t validity)
{
switch(validity) {
case GPGME_VALIDITY_UNKNOWN:
return "unknown";
case GPGME_VALIDITY_UNDEFINED:
return "undefined";
case GPGME_VALIDITY_NEVER:
return "never";
case GPGME_VALIDITY_MARGINAL:
return "marginal";
case GPGME_VALIDITY_FULL:
return "full";
case GPGME_VALIDITY_ULTIMATE:
return "ultimate";
}
return "???";
}
static void sigsum_test_bit(gpgme_sigsum_t sigsum, alpm_list_t **summary,
gpgme_sigsum_t bit, const char *value)
{
if(sigsum & bit) {
*summary = alpm_list_add(*summary, (void *)value);
}
}
static alpm_list_t *list_sigsum(gpgme_sigsum_t sigsum)
{
alpm_list_t *summary = NULL;
/* The docs say this can be a bitmask...not sure I believe it, but we'll code
* for it anyway and show all possible flags in the returned string. */
/* The signature is fully valid. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_VALID, "valid");
/* The signature is good. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_GREEN, "green");
/* The signature is bad. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_RED, "red");
/* One key has been revoked. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_REVOKED, "key revoked");
/* One key has expired. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_EXPIRED, "key expired");
/* The signature has expired. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_SIG_EXPIRED, "sig expired");
/* Can't verify: key missing. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_KEY_MISSING, "key missing");
/* CRL not available. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_CRL_MISSING, "crl missing");
/* Available CRL is too old. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_CRL_TOO_OLD, "crl too old");
/* A policy was not met. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_BAD_POLICY, "bad policy");
/* A system error occured. */
sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_SYS_ERROR, "sys error");
/* Fallback case */
if(!sigsum) {
summary = alpm_list_add(summary, (void *)"(empty)");
}
return summary;
}
static int init_gpgme(alpm_handle_t *handle)
{
static int init = 0;
const char *version, *sigdir;
gpgme_error_t err;
gpgme_engine_info_t enginfo;
if(init) {
/* we already successfully initialized the library */
return 0;
}
sigdir = alpm_option_get_gpgdir(handle);
if (_alpm_access(handle, sigdir, "pubring.gpg", R_OK)
|| _alpm_access(handle, sigdir, "trustdb.gpg", R_OK)) {
handle->pm_errno = ALPM_ERR_NOT_A_FILE;
_alpm_log(handle, ALPM_LOG_DEBUG, "Signature verification will fail!\n");
}
/* calling gpgme_check_version() returns the current version and runs
* some internal library setup code */
version = gpgme_check_version(NULL);
_alpm_log(handle, ALPM_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, sigdir);
CHECK_ERR();
err = gpgme_get_engine_info(&enginfo);
CHECK_ERR();
_alpm_log(handle, ALPM_LOG_DEBUG, "GPGME engine info: file=%s, home=%s\n",
enginfo->file_name, enginfo->home_dir);
init = 1;
return 0;
error:
_alpm_log(handle, ALPM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
RET_ERR(handle, ALPM_ERR_GPGME, 1);
}
/**
* Decode a loaded signature in base64 form.
* @param base64_data the signature to attempt to decode
* @param data the decoded data; must be freed by the caller
* @param data_len the length of the returned data
* @return 0 on success, 1 on failure to properly decode
*/
static int decode_signature(const char *base64_data,
unsigned char **data, size_t *data_len) {
size_t len = strlen(base64_data);
unsigned char *usline = (unsigned char *)base64_data;
/* reasonable allocation of expected length is 3/4 of encoded length */
size_t destlen = len * 3 / 4;
MALLOC(*data, destlen, goto error);
if(base64_decode(*data, &destlen, usline, len)) {
goto error;
}
*data_len = destlen;
return 0;
error:
*data = NULL;
*data_len = 0;
return 1;
}
/**
* Form a signature path given a file path.
* Caller must free the result.
* @param handle the context handle
* @param path the full path to a file
* @return the path with '.sig' appended, NULL on errors
*/
char *_alpm_sigpath(alpm_handle_t *handle, const char *path)
{
char *sigpath;
size_t len;
if(!path) {
return NULL;
}
len = strlen(path) + 5;
CALLOC(sigpath, len, sizeof(char), RET_ERR(handle, ALPM_ERR_MEMORY, NULL));
sprintf(sigpath, "%s.sig", path);
return sigpath;
}
/**
* Check the PGP signature for the given file path.
* If base64_sig is provided, it will be used as the signature data after
* decoding. If base64_sig is NULL, expect a signature file next to path
* (e.g. "%s.sig").
*
* The return value will be 0 if nothing abnormal happened during the signature
* check, and -1 if an error occurred while checking signatures or if a
* signature could not be found; pm_errno will be set. Note that "abnormal"
* does not include a failed signature; the value in #result should be checked
* to determine if the signature(s) are good.
* @param handle the context handle
* @param path the full path to a file
* @param base64_sig optional PGP signature data in base64 encoding
* @result
* @return 0 in normal cases, -1 if the something failed in the check process
*/
int _alpm_gpgme_checksig(alpm_handle_t *handle, const char *path,
const char *base64_sig, alpm_sigresult_t *result)
{
int ret = -1, sigcount;
gpgme_error_t err;
gpgme_ctx_t ctx;
gpgme_data_t filedata, sigdata;
gpgme_verify_result_t verify_result;
gpgme_signature_t gpgsig;
char *sigpath = NULL;
unsigned char *decoded_sigdata = NULL;
FILE *file = NULL, *sigfile = NULL;
if(!path || _alpm_access(handle, NULL, path, R_OK) != 0) {
RET_ERR(handle, ALPM_ERR_NOT_A_FILE, -1);
}
if(!result) {
RET_ERR(handle, ALPM_ERR_WRONG_ARGS, -1);
}
result->count = 0;
if(!base64_sig) {
sigpath = _alpm_sigpath(handle, path);
/* this will just help debugging */
_alpm_access(handle, NULL, sigpath, R_OK);
}
if(init_gpgme(handle)) {
/* pm_errno was set in gpgme_init() */
return -1;
}
_alpm_log(handle, ALPM_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) {
handle->pm_errno = ALPM_ERR_NOT_A_FILE;
goto error;
}
err = gpgme_data_new_from_stream(&filedata, file);
CHECK_ERR();
/* next create data object for the signature */
if(base64_sig) {
/* memory-based, we loaded it from a sync DB */
size_t data_len;
int decode_ret = decode_signature(base64_sig,
&decoded_sigdata, &data_len);
if(decode_ret) {
handle->pm_errno = ALPM_ERR_SIG_INVALID;
goto error;
}
err = gpgme_data_new_from_mem(&sigdata,
(char *)decoded_sigdata, data_len, 0);
} else {
/* file-based, it is on disk */
sigfile = fopen(sigpath, "rb");
if(sigfile == NULL) {
_alpm_log(handle, ALPM_LOG_DEBUG, "sig path %s could not be opened\n",
sigpath);
handle->pm_errno = ALPM_ERR_SIG_MISSING;
goto error;
}
err = gpgme_data_new_from_stream(&sigdata, sigfile);
}
CHECK_ERR();
/* here's where the magic happens */
err = gpgme_op_verify(ctx, sigdata, filedata, NULL);
CHECK_ERR();
verify_result = gpgme_op_verify_result(ctx);
CHECK_ERR();
if(!verify_result || !verify_result->signatures) {
_alpm_log(handle, ALPM_LOG_DEBUG, "no signatures returned\n");
handle->pm_errno = ALPM_ERR_SIG_MISSING;
goto error;
}
for(gpgsig = verify_result->signatures, sigcount = 0;
gpgsig; gpgsig = gpgsig->next, sigcount++);
_alpm_log(handle, ALPM_LOG_DEBUG, "%d signatures returned\n", sigcount);
result->status = calloc(sigcount, sizeof(alpm_sigstatus_t));
result->validity = calloc(sigcount, sizeof(alpm_sigvalidity_t));
result->uid = calloc(sigcount, sizeof(char*));
if(!result->status || !result->validity || !result->uid) {
handle->pm_errno = ALPM_ERR_MEMORY;
goto error;
}
result->count = sigcount;
for(gpgsig = verify_result->signatures, sigcount = 0; gpgsig;
gpgsig = gpgsig->next, sigcount++) {
alpm_list_t *summary_list, *summary;
alpm_sigstatus_t status;
alpm_sigvalidity_t validity;
gpgme_key_t key;
_alpm_log(handle, ALPM_LOG_DEBUG, "fingerprint: %s\n", gpgsig->fpr);
summary_list = list_sigsum(gpgsig->summary);
for(summary = summary_list; summary; summary = summary->next) {
_alpm_log(handle, ALPM_LOG_DEBUG, "summary: %s\n", (const char *)summary->data);
}
alpm_list_free(summary_list);
_alpm_log(handle, ALPM_LOG_DEBUG, "status: %s\n", gpgme_strerror(gpgsig->status));
_alpm_log(handle, ALPM_LOG_DEBUG, "timestamp: %lu\n", gpgsig->timestamp);
_alpm_log(handle, ALPM_LOG_DEBUG, "exp_timestamp: %lu\n", gpgsig->exp_timestamp);
_alpm_log(handle, ALPM_LOG_DEBUG, "validity: %s; reason: %s\n",
string_validity(gpgsig->validity),
gpgme_strerror(gpgsig->validity_reason));
err = gpgme_get_key(ctx, gpgsig->fpr, &key, 0);
if(gpg_err_code(err) == GPG_ERR_EOF) {
_alpm_log(handle, ALPM_LOG_DEBUG, "key lookup failed, unknown key\n");
err = GPG_ERR_NO_ERROR;
STRDUP(result->uid[sigcount], gpgsig->fpr,
handle->pm_errno = ALPM_ERR_MEMORY; goto error);
} else {
CHECK_ERR();
if(key->uids) {
const char *uid = key->uids->uid;
STRDUP(result->uid[sigcount], uid,
handle->pm_errno = ALPM_ERR_MEMORY; goto error);
_alpm_log(handle, ALPM_LOG_DEBUG, "key user: %s\n", uid);
}
gpgme_key_unref(key);
}
switch(gpg_err_code(gpgsig->status)) {
/* good cases */
case GPG_ERR_NO_ERROR:
status = ALPM_SIGSTATUS_VALID;
break;
case GPG_ERR_KEY_EXPIRED:
status = ALPM_SIGSTATUS_KEY_EXPIRED;
break;
/* bad cases */
case GPG_ERR_SIG_EXPIRED:
status = ALPM_SIGSTATUS_SIG_EXPIRED;
break;
case GPG_ERR_NO_PUBKEY:
status = ALPM_SIGSTATUS_KEY_UNKNOWN;
break;
case GPG_ERR_BAD_SIGNATURE:
default:
status = ALPM_SIGSTATUS_INVALID;
break;
}
if(status == ALPM_SIGSTATUS_VALID
|| status == ALPM_SIGSTATUS_KEY_EXPIRED) {
switch(gpgsig->validity) {
case GPGME_VALIDITY_ULTIMATE:
case GPGME_VALIDITY_FULL:
validity = ALPM_SIGVALIDITY_FULL;
break;
case GPGME_VALIDITY_MARGINAL:
validity = ALPM_SIGVALIDITY_MARGINAL;
break;
case GPGME_VALIDITY_NEVER:
validity = ALPM_SIGVALIDITY_NEVER;
break;
case GPGME_VALIDITY_UNKNOWN:
case GPGME_VALIDITY_UNDEFINED:
default:
validity = ALPM_SIGVALIDITY_UNKNOWN;
break;
}
} else {
validity = ALPM_SIGVALIDITY_NEVER;
}
result->status[sigcount] = status;
result->validity[sigcount] = validity;
}
ret = 0;
error:
gpgme_data_release(sigdata);
gpgme_data_release(filedata);
gpgme_release(ctx);
if(sigfile) {
fclose(sigfile);
}
if(file) {
fclose(file);
}
FREE(sigpath);
FREE(decoded_sigdata);
if(gpg_err_code(err) != GPG_ERR_NO_ERROR) {
_alpm_log(handle, ALPM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
RET_ERR(handle, ALPM_ERR_GPGME, -1);
}
return ret;
}
#else
int _alpm_gpgme_checksig(alpm_handle_t UNUSED *handle, const char UNUSED *path,
const char UNUSED *base64_sig, alpm_sigresult_t UNUSED *result)
{
return -1;
}
#endif
int _alpm_check_pgp_helper(alpm_handle_t *handle, const char *path,
const char *base64_sig, int optional, int marginal, int unknown,
enum _alpm_errno_t invalid_err)
{
alpm_sigresult_t result;
int ret;
memset(&result, 0, sizeof(result));
_alpm_log(handle, ALPM_LOG_DEBUG, "checking signatures for %s\n", path);
ret = _alpm_gpgme_checksig(handle, path, base64_sig, &result);
if(ret && handle->pm_errno == ALPM_ERR_SIG_MISSING) {
if(optional) {
_alpm_log(handle, ALPM_LOG_DEBUG, "missing optional signature\n");
handle->pm_errno = 0;
ret = 0;
} else {
_alpm_log(handle, ALPM_LOG_DEBUG, "missing required signature\n");
/* ret will already be -1 */
}
} else if(ret) {
_alpm_log(handle, ALPM_LOG_DEBUG, "signature check failed\n");
/* ret will already be -1 */
} else {
int num;
for(num = 0; !ret && num < result.count; num++) {
switch(result.status[num]) {
case ALPM_SIGSTATUS_VALID:
case ALPM_SIGSTATUS_KEY_EXPIRED:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature is valid\n");
switch(result.validity[num]) {
case ALPM_SIGVALIDITY_FULL:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature is fully trusted\n");
break;
case ALPM_SIGVALIDITY_MARGINAL:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature is marginal trust\n");
if(!marginal) {
ret = -1;
}
break;
case ALPM_SIGVALIDITY_UNKNOWN:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature is unknown trust\n");
if(!unknown) {
ret = -1;
}
break;
case ALPM_SIGVALIDITY_NEVER:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature should never be trusted\n");
ret = -1;
break;
}
break;
case ALPM_SIGSTATUS_SIG_EXPIRED:
case ALPM_SIGSTATUS_KEY_UNKNOWN:
case ALPM_SIGSTATUS_INVALID:
_alpm_log(handle, ALPM_LOG_DEBUG, "signature is not valid\n");
ret = -1;
break;
}
}
if(ret) {
handle->pm_errno = invalid_err;
}
}
alpm_sigresult_cleanup(&result);
return ret;
}
/**
* Check the PGP signature for the given package file.
* @param pkg the package to check
* @return a int value : 0 (valid), 1 (invalid), -1 (an error occurred)
*/
int SYMEXPORT alpm_pkg_check_pgp_signature(alpm_pkg_t *pkg,
alpm_sigresult_t *result)
{
ASSERT(pkg != NULL, return -1);
ASSERT(result != NULL, RET_ERR(pkg->handle, ALPM_ERR_WRONG_ARGS, -1));
pkg->handle->pm_errno = 0;
return _alpm_gpgme_checksig(pkg->handle, alpm_pkg_get_filename(pkg),
pkg->base64_sig, result);
}
/**
* Check the PGP signature for the given database.
* @param db the database to check
* @return a int value : 0 (valid), 1 (invalid), -1 (an error occurred)
*/
int SYMEXPORT alpm_db_check_pgp_signature(alpm_db_t *db,
alpm_sigresult_t *result)
{
ASSERT(db != NULL, return -1);
ASSERT(result != NULL, RET_ERR(db->handle, ALPM_ERR_WRONG_ARGS, -1));
db->handle->pm_errno = 0;
return _alpm_gpgme_checksig(db->handle, _alpm_db_path(db), NULL, result);
}
int SYMEXPORT alpm_sigresult_cleanup(alpm_sigresult_t *result)
{
ASSERT(result != NULL, return -1);
/* Because it is likely result is on the stack, uid and status may have bogus
* values in the struct. Only look at them if count is greater than 0. */
if(result->count > 0) {
free(result->status);
if(result->uid) {
int i;
for(i = 0; i < result->count; i++) {
free(result->uid[i]);
}
free(result->uid);
}
}
return 0;
}
/* vim: set ts=2 sw=2 noet: */
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