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-rw-r--r--lib/libalpm/signing.c403
1 files changed, 403 insertions, 0 deletions
diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
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+++ b/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"
+
+#if HAVE_LIBGPGME
+#define CHECK_ERR(void) do { \
+ if(err != GPG_ERR_NO_ERROR) { goto error; } \
+ } while(0)
+
+static const char *gpgme_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 alpm_list_t *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);
+ }
+ return summary;
+}
+
+static alpm_list_t *gpgme_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. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_VALID, "valid");
+ /* The signature is good. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_GREEN, "green");
+ /* The signature is bad. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_RED, "red");
+ /* One key has been revoked. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_KEY_REVOKED, "key revoked");
+ /* One key has expired. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_KEY_EXPIRED, "key expired");
+ /* The signature has expired. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_SIG_EXPIRED, "sig expired");
+ /* Can't verify: key missing. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_KEY_MISSING, "key missing");
+ /* CRL not available. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_CRL_MISSING, "crl missing");
+ /* Available CRL is too old. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_CRL_TOO_OLD, "crl too old");
+ /* A policy was not met. */
+ summary = sigsum_test_bit(sigsum, summary, GPGME_SIGSUM_BAD_POLICY, "bad policy");
+ /* A system error occured. */
+ summary = 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 gpgme_init(void)
+{
+ static int init = 0;
+ const char *version;
+ gpgme_error_t err;
+ gpgme_engine_info_t enginfo;
+
+ 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);
+}
+
+/**
+ * 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, int *data_len) {
+ unsigned char *usline;
+ int len;
+
+ len = strlen(base64_data);
+ usline = (unsigned char *)base64_data;
+ int ret, destlen = 0;
+ /* get the necessary size for the buffer by passing 0 */
+ ret = base64_decode(NULL, &destlen, usline, len);
+ if(ret != 0 && ret != POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL) {
+ goto error;
+ }
+ /* alloc our memory and repeat the call to decode */
+ MALLOC(*data, (size_t)destlen, goto error);
+ ret = base64_decode(*data, &destlen, usline, len);
+ if(ret != 0) {
+ goto error;
+ }
+ *data_len = destlen;
+ return 0;
+
+error:
+ *data = NULL;
+ *data_len = 0;
+ return 1;
+}
+
+/**
+ * Check the PGP signature for the given file.
+ * @param path the full path to a file
+ * @param base64_sig PGP signature data in base64 encoding; if NULL, expect a
+ * signature file next to 'path'
+ * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
+ */
+int _alpm_gpgme_checksig(const char *path, const char *base64_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;
+ char *sigpath = NULL;
+ unsigned char *decoded_sigdata = NULL;
+ FILE *file = NULL, *sigfile = NULL;
+
+ if(!path || access(path, R_OK) != 0) {
+ RET_ERR(PM_ERR_NOT_A_FILE, -1);
+ }
+
+ if(!base64_sig) {
+ size_t len = strlen(path) + 5;
+ CALLOC(sigpath, len, sizeof(char), RET_ERR(PM_ERR_MEMORY, -1));
+ snprintf(sigpath, len, "%s.sig", path);
+
+ if(!access(sigpath, R_OK) == 0) {
+ FREE(sigpath);
+ RET_ERR(PM_ERR_SIG_UNKNOWN, -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 */
+ if(base64_sig) {
+ /* memory-based, we loaded it from a sync DB */
+ int data_len;
+ int decode_ret = decode_signature(base64_sig,
+ &decoded_sigdata, &data_len);
+ if(decode_ret) {
+ ret = -1;
+ 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) {
+ pm_errno = PM_ERR_NOT_A_FILE;
+ ret = -1;
+ 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();
+ result = gpgme_op_verify_result(ctx);
+ gpgsig = result->signatures;
+ if(!gpgsig || gpgsig->next) {
+ int count = 0;
+ while(gpgsig) {
+ count++;
+ gpgsig = gpgsig->next;
+ }
+ _alpm_log(PM_LOG_ERROR, _("Unexpected number of signatures (%d)\n"),
+ count);
+ ret = -1;
+ goto error;
+ }
+
+ {
+ alpm_list_t *summary_list, *summary;
+
+ _alpm_log(PM_LOG_DEBUG, "fingerprint: %s\n", gpgsig->fpr);
+ summary_list = gpgme_list_sigsum(gpgsig->summary);
+ for(summary = summary_list; summary; summary = summary->next) {
+ _alpm_log(PM_LOG_DEBUG, "summary: %s\n", (const char *)summary->data);
+ }
+ alpm_list_free(summary_list);
+ _alpm_log(PM_LOG_DEBUG, "status: %s\n", gpgme_strerror(gpgsig->status));
+ _alpm_log(PM_LOG_DEBUG, "timestamp: %lu\n", gpgsig->timestamp);
+ _alpm_log(PM_LOG_DEBUG, "exp_timestamp: %lu\n", gpgsig->exp_timestamp);
+ _alpm_log(PM_LOG_DEBUG, "validity: %s\n",
+ gpgme_string_validity(gpgsig->validity));
+ _alpm_log(PM_LOG_DEBUG, "validity_reason: %s\n",
+ gpgme_strerror(gpgsig->validity_reason));
+ _alpm_log(PM_LOG_DEBUG, "pubkey algo: %s\n",
+ gpgme_pubkey_algo_name(gpgsig->pubkey_algo));
+ _alpm_log(PM_LOG_DEBUG, "hash algo: %s\n",
+ gpgme_hash_algo_name(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);
+ }
+ FREE(sigpath);
+ FREE(decoded_sigdata);
+ 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;
+}
+#else
+int _alpm_gpgme_checksig(const char *path, const char *base64_sig)
+{
+ return -1;
+}
+#endif
+
+/**
+ * Determines the necessity of checking for a valid PGP signature
+ * @param db the sync database to query
+ *
+ * @return signature verification level
+ */
+pgp_verify_t _alpm_db_get_sigverify_level(pmdb_t *db)
+{
+ ASSERT(db != NULL, RET_ERR(PM_ERR_DB_NULL, PM_PGP_VERIFY_UNKNOWN));
+
+ if(db->pgp_verify != PM_PGP_VERIFY_UNKNOWN) {
+ return db->pgp_verify;
+ } else {
+ return alpm_option_get_default_sigverify();
+ }
+}
+
+/**
+ * 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(pmpkg_t *pkg)
+{
+ ASSERT(pkg != NULL, return 0);
+
+ return _alpm_gpgme_checksig(alpm_pkg_get_filename(pkg), pkg->base64_sig);
+}
+
+/**
+ * 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(pmdb_t *db)
+{
+ ASSERT(db != NULL, return 0);
+
+ return _alpm_gpgme_checksig(_alpm_db_path(db), NULL);
+}
+
+/* vim: set ts=2 sw=2 noet: */