1 files changed, 406 insertions, 0 deletions

diff --git a/lib/libalpm/signing.c b/lib/libalpm/signing.c
new file mode 100644
index 00000000..ff97d4c7
--- /dev/null
+++ b/lib/libalpm/signing.c
@@ -0,0 +1,406 @@
+/*
+ *  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_signaturedir(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: */