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/* wydawca - automatic release submission daemon
   Copyright (C) 2007, 2010, 2011, 2012, 2013, 2017, 2019 Sergey
   Poznyakoff

   Wydawca 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 3 of the License, or (at your
   option) any later version.

   Wydawca 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 wydawca. If not, see <http://www.gnu.org/licenses/>. */

/* GPG interface functions */

#include "wydawca.h"
#include <gpgme.h>

#define fail_if_err(expr) do {						\
		int a = expr;						\
		if (a) {						\
			wy_log(LOG_ERR, _("%s: GPGME error: %s"), #expr, \
			       gpgme_strerror(a));			\
			return 1;					\
		}							\
	} while (0)

char *temp_homedir;

static int rmdir_r(const char *name);

/* Auxiliary function: change to directory NAME and recursively remove
   everything under it. */
static int
recursive_rmdir(const char *name)
{
	int rc;
	DIR *dir;
	struct dirent *ent;

	if (chdir(name)) {
		wy_log(LOG_ERR, _("cannot change to directory %s: %s"),
		       name, strerror(errno));
		return 1;
	}

	dir = opendir(".");
	if (!dir) {
		wy_log(LOG_ERR, _("cannot open directory %s: %s"),
		       name, strerror(errno));
		return 1;
	}

	for (rc = 0; rc == 0 && (ent = readdir(dir));) {
		struct stat st;

		if (strcmp(ent->d_name, ".") == 0
		    || strcmp(ent->d_name, "..") == 0)
			continue;

		if (stat(ent->d_name, &st) && errno != ENOENT) {
			wy_log(LOG_ERR, _("cannot stat file `%s': %s"),
			       name, strerror(errno));
			rc = 1;
		} else if (S_ISDIR(st.st_mode))
			rc = rmdir_r(ent->d_name);
		else if ((rc = unlink(ent->d_name)) != 0 && errno != ENOENT)
			wy_log(LOG_ERR, _("cannot unlink %s: %s"),
			       ent->d_name, strerror(errno));
	}
	closedir(dir);
	return rc;
}

/* Recursively remove the contents of the directory NAME and the directory
   itself. Do not change CWD. */
static int
rmdir_r(const char *name)
{
	int rc;

	if (push_dir(NULL)) {
		wy_log(LOG_ERR, _("cannot save current directory: %s"),
		       strerror(errno));
		return 1;
	}
	rc = recursive_rmdir(name);
	if (pop_dir()) {
		wy_log(LOG_ERR, _("cannot restore current directory: %s"),
		       strerror(errno));
		rc = 1;
	}

	if (rc == 0 && rmdir(name)) {
		wy_log(LOG_ERR, _("cannot remove directory %s: %s"),
		       name, strerror(errno));
		return 1;
	}

	return rc;
}

/* Remove temporary GPG home directory */
static void
remove_homedir()
{
	wy_debug(2, (_("removing GNUPG home directory: %s"), temp_homedir));
	if (rmdir_r(temp_homedir))
		wy_log(LOG_CRIT, _("failed to remove GPG directory %s"),
		       temp_homedir);
}

/* Create a temporary GPG home directory */
static int
create_gpg_homedir()
{
	if (temp_homedir)
		return 0;

	temp_homedir = grecs_strdup("/tmp/wydawca-XXXXXX");
	if (!mkdtemp(temp_homedir)) {
		wy_log(LOG_CRIT,
		       _("cannot create GPG home directory (%s): %s"),
		       temp_homedir, strerror(errno));
		return 1;
	}
	atexit(remove_homedir);
	wy_debug(2, (_("GNUPG home directory: %s"), temp_homedir));
	setenv("GNUPGHOME", temp_homedir, 1);
	return 0;
}

static int
checksig(gpgme_signature_t sig, const char *uid, struct wy_triplet *trp)
{
	switch (gpg_err_code(sig->status)) {
	case GPG_ERR_NO_ERROR:
		wy_debug(1, (_("Good signature from %s"), uid));
		trp->uploader = uploader_find_frp(trp->uploader_list,
						  sig->fpr);
		if (!trp->uploader) {
			wy_log(LOG_ERR,
			       _("good signature from %s, "
				 "but the uploader info for %s not found"),
			       uid, sig->fpr);
			return 1;
		}
		break;

	case GPG_ERR_BAD_SIGNATURE:
		UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
		wy_log(LOG_ERR, _("BAD signature from %s"), uid);
		return 0;

	case GPG_ERR_NO_PUBKEY:
		UPDATE_STATS(WY_STAT_ACCESS_VIOLATIONS);
		wy_log(LOG_ERR, _("No public key"));
		return 0;

	case GPG_ERR_NO_DATA:
		UPDATE_STATS(WY_STAT_BAD_TRIPLETS);
		wy_log(LOG_ERR, _("No signature"));
		return 0;

	case GPG_ERR_SIG_EXPIRED:
		UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
		wy_log(LOG_ERR, _("Expired signature from %s"), uid);
		return 0;

	case GPG_ERR_KEY_EXPIRED:
		UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
		wy_log(LOG_ERR, _("Key expired (%s)"), uid);
		return 0;

	default:
		wy_log(LOG_ERR, _("Unknown signature error"));
		return 0;
	}
	return -1;
}

static int
gpg_verify_signature(gpgme_ctx_t ctx, gpgme_signature_t sig,
		     struct wy_triplet *trp)
{
	if (!sig)
		return 0;

	for (; sig; sig = sig->next) {
		const char *uid;
		gpgme_key_t key;
		int rc;

		if (gpgme_get_key(ctx, sig->fpr, &key, 0) == GPG_ERR_NO_ERROR)
			uid = key->uids->uid;
		else
			uid = sig->fpr;
		rc = checksig(sig, uid, trp);
		gpgme_key_unref(key);
		if (rc != -1)
			return rc;
	}
	return 1;
}

/* Verify the directive file from TRP using public key PUBKEY */
int
verify_directive_signature(struct wy_triplet *trp)
{
	gpgme_ctx_t ctx;
	gpgme_data_t key_data, directive_data, plain = NULL;
	gpgme_error_t ec;
	int rc;
	struct wy_user *uptr;

	create_gpg_homedir();
	fail_if_err(gpgme_new(&ctx));

	for (uptr = wy_triplet_get_uploaders(trp); uptr; uptr = uptr->next) {
		gpgme_import_result_t res;
		gpgme_import_status_t pstat;

		fail_if_err(gpgme_data_new_from_mem(&key_data,
						    uptr->gpg_key,
						    strlen(uptr->gpg_key), 0));
		fail_if_err(gpgme_op_import(ctx, key_data));
		res = gpgme_op_import_result(ctx);
		pstat = res->imports;
		uptr->fpr = grecs_strdup(pstat->fpr);
		wy_debug(3, (_("imported key: user = %s, fingerprint = %s"),
			     uptr->name, uptr->fpr));
	}

	fail_if_err(gpgme_data_new_from_file(&directive_data,
					     trp->file[file_directive].name,
					     1));
	gpgme_data_new(&plain);
	ec = gpgme_op_verify(ctx, directive_data, NULL, plain);
	if (ec == GPG_ERR_NO_ERROR) {
		gpgme_verify_result_t result;

		result = gpgme_op_verify_result(ctx);
		if (!gpg_verify_signature(ctx, result->signatures, trp)) {
			UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
			notify(trp->spool->notification, trp,
			       wy_ev_bad_directive_signature);
			rc = 1;
		} else
			rc = 0;
	} else {
		rc = 1;
		UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
		wy_log(LOG_ERR, _("%s: directive verification failed: %s"),
		       trp->name, gpgme_strerror(ec));
	}

	gpgme_data_release(plain);
	gpgme_data_release(directive_data);
	gpgme_data_release(key_data);
	gpgme_release(ctx);

	return rc;
}

/* Verify the detached signature of TRP.
   NOTE: It is assumed that the public key is already registered (by
   a previous call to verify_directive_signature). */
int
verify_detached_signature(struct wy_triplet *trp)
{
	gpgme_engine_info_t info;
	const char *argv[5];
	const struct spool *spool;

	ASGN_SPOOL(spool, trp, return 1);

	fail_if_err(gpgme_get_engine_info(&info));
	while (info && info->protocol != GPGME_PROTOCOL_OpenPGP)
		info = info->next;
	if (!info) {
		wy_log(LOG_CRIT,
		       _("cannot find path to gpg binary (attempting to "
			 "verify the detached signature for %s"), trp->name);
		return 1;
	}

	create_gpg_homedir();
	argv[0] = info->file_name;
	argv[1] = "--verify";
	argv[2] = trp->file[file_signature].name;
	argv[3] = trp->file[file_dist].name;
	argv[4] = NULL;

	switch (wydawca_exec(5, argv, NULL)) {
	case exec_success:
		wy_debug(1, (_("good detached signature for %s"), trp->name));
		return 0;

	case exec_fail:
		UPDATE_STATS(WY_STAT_BAD_SIGNATURE);
		wy_log(LOG_ERR, _("BAD detached signature for %s"), trp->name);
		notify(spool->notification, trp, wy_ev_bad_detached_signature);
		break;

	case exec_error:
		wy_log(LOG_CRIT, _("cannot verify detached signature for %s"),
		       trp->name);
		break;
	}

	return 1;
}

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