/* * 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(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 */ sigsum_test_bit(sigsum, &summary, GPGME_SIGSUM_RED, "red"); /* One key has been revoked.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(pmhandle_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(!sigdir) { RET_ERR(handle, 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(handle, 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, sigdir); CHECK_ERR(); err = gpgme_get_engine_info(&enginfo); CHECK_ERR(); _alpm_log(handle, PM_LOG_DEBUG, "GPGME engine info: file=%s, home=%s\n", enginfo->file_name, enginfo->home_dir); init = 1; return 0; error: _alpm_log(handle, PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err)); RET_ERR(handle, 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 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 all checked signatures are * valid, 1 if there was some sort of problem (but not necessarily rejection), * and -1 if an error occurred while checking signatures. If 1 is returned, * pm_errno should be checked to see why the signatures did not pass muster. * @param handle the context handle * @param path the full path to a file * @param base64_sig optional PGP signature data in base64 encoding * @return a int value : 0 (valid), 1 (invalid), -1 (an error occurred) */ int _alpm_gpgme_checksig(pmhandle_t *handle, 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(handle, PM_ERR_NOT_A_FILE, -1); } if(!base64_sig) { size_t len = strlen(path) + 5; CALLOC(sigpath, len, sizeof(char), RET_ERR(handle, PM_ERR_MEMORY, -1)); snprintf(sigpath, len, "%s.sig", path); if(!access(sigpath, R_OK) == 0) { FREE(sigpath); RET_ERR(handle, PM_ERR_SIG_UNKNOWN, -1); } } if(init_gpgme(handle)) { /* pm_errno was set in gpgme_init() */ return -1; } _alpm_log(handle, 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) { handle->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) { handle->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) { _alpm_log(handle, PM_LOG_DEBUG, "no signatures returned\n"); ret = -1; goto error; } { alpm_list_t *summary_list, *summary; _alpm_log(handle, PM_LOG_DEBUG, "fingerprint: %s\n", gpgsig->fpr); summary_list = list_sigsum(gpgsig->summary); for(summary = summary_list; summary; summary = summary->next) { _alpm_log(handle, PM_LOG_DEBUG, "summary: %s\n", (const char *)summary->data); } alpm_list_free(summary_list); _alpm_log(handle, PM_LOG_DEBUG, "status: %s\n", gpgme_strerror(gpgsig->status)); _alpm_log(handle, PM_LOG_DEBUG, "timestamp: %lu\n", gpgsig->timestamp); _alpm_log(handle, PM_LOG_DEBUG, "exp_timestamp: %lu\n", gpgsig->exp_timestamp); _alpm_log(handle, PM_LOG_DEBUG, "validity: %s\n", string_validity(gpgsig->validity)); _alpm_log(handle, PM_LOG_DEBUG, "validity_reason: %s\n", gpgme_strerror(gpgsig->validity_reason)); _alpm_log(handle, PM_LOG_DEBUG, "pubkey algo: %s\n", gpgme_pubkey_algo_name(gpgsig->pubkey_algo)); _alpm_log(handle, 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(handle, 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(handle, PM_LOG_WARNING, _("File %s has a green signature.\n"), path); } else if(gpgsig->summary & GPGME_SIGSUM_KEY_MISSING) { handle->pm_errno = PM_ERR_SIG_UNKNOWN; _alpm_log(handle, PM_LOG_WARNING, _("File %s has a signature from an unknown key.\n"), path); ret = -1; } else { /* we'll capture everything else here */ handle->pm_errno = PM_ERR_SIG_INVALID; _alpm_log(handle, 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(handle, PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err)); RET_ERR(handle, PM_ERR_GPGME, -1); } return ret; } #else int _alpm_gpgme_checksig(pmhandle_t *handle, 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) { if(db->pgp_verify != PM_PGP_VERIFY_UNKNOWN) { return db->pgp_verify; } else { return alpm_option_get_default_sigverify(db->handle); } } /** * 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 -1); pkg->handle->pm_errno = 0; return _alpm_gpgme_checksig(pkg->handle, 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 -1); db->handle->pm_errno = 0; return _alpm_gpgme_checksig(db->handle, _alpm_db_path(db), NULL); } /* vim: set ts=2 sw=2 noet: */