1 files changed, 214 insertions, 0 deletions
diff --git a/src/auth/passdb-cache.c b/src/auth/passdb-cache.c
new file mode 100644
index 0000000..2e73134
--- /dev/null
+++ b/src/auth/passdb-cache.c
@@ -0,0 +1,214 @@
+/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */
+
+#include "auth-common.h"
+#include "str.h"
+#include "strescape.h"
+#include "restrict-process-size.h"
+#include "auth-request-stats.h"
+#include "auth-worker-server.h"
+#include "password-scheme.h"
+#include "passdb.h"
+#include "passdb-cache.h"
+#include "passdb-blocking.h"
+
+struct auth_cache *passdb_cache = NULL;
+
+static void
+passdb_cache_log_hit(struct auth_request *request, const char *value)
+{
+	const char *p;
+
+	if (!request->set->debug_passwords &&
+	    *value != '\0' && *value != '\t') {
+		/* hide the password */
+		p = strchr(value, '\t');
+		value = t_strconcat(PASSWORD_HIDDEN_STR, p, NULL);
+	}
+	e_debug(authdb_event(request), "cache hit: %s", value);
+}
+
+static bool
+passdb_cache_lookup(struct auth_request *request, const char *key,
+		    bool use_expired, struct auth_cache_node **node_r,
+		    const char **value_r, bool *neg_expired_r)
+{
+	struct auth_stats *stats = auth_request_stats_get(request);
+	const char *value;
+	bool expired;
+
+	request->passdb_cache_result = AUTH_REQUEST_CACHE_MISS;
+
+	/* value = password \t ... */
+	value = auth_cache_lookup(passdb_cache, request, key, node_r,
+				  &expired, neg_expired_r);
+	if (value == NULL || (expired && !use_expired)) {
+		stats->auth_cache_miss_count++;
+		e_debug(authdb_event(request),
+			value == NULL ? "cache miss" :
+			"cache expired");
+		return FALSE;
+	}
+	stats->auth_cache_hit_count++;
+	passdb_cache_log_hit(request, value);
+	request->passdb_cache_result = AUTH_REQUEST_CACHE_HIT;
+
+	*value_r = value;
+	return TRUE;
+}
+
+static bool
+passdb_cache_verify_plain_callback(struct auth_worker_connection *conn ATTR_UNUSED,
+				   const char *reply, void *context)
+{
+	struct auth_request *request = context;
+	enum passdb_result result;
+
+	result = passdb_blocking_auth_worker_reply_parse(request, reply);
+	if (result != PASSDB_RESULT_OK)
+		auth_fields_rollback(request->fields.extra_fields);
+	auth_request_verify_plain_callback_finish(result, request);
+	auth_request_unref(&request);
+	return TRUE;
+}
+
+bool passdb_cache_verify_plain(struct auth_request *request, const char *key,
+			       const char *password,
+			       enum passdb_result *result_r, bool use_expired)
+{
+	const char *value, *cached_pw, *scheme, *const *list;
+	struct auth_cache_node *node;
+	int ret;
+	bool neg_expired;
+
+	if (passdb_cache == NULL || key == NULL)
+		return FALSE;
+
+	if (!passdb_cache_lookup(request, key, use_expired,
+				 &node, &value, &neg_expired))
+		return FALSE;
+
+	if (*value == '\0') {
+		/* negative cache entry */
+		auth_request_log_unknown_user(request, AUTH_SUBSYS_DB);
+		*result_r = PASSDB_RESULT_USER_UNKNOWN;
+		auth_request_verify_plain_callback_finish(*result_r, request);
+		return TRUE;
+	}
+
+	list = t_strsplit_tabescaped(value);
+
+	cached_pw = list[0];
+	if (*cached_pw == '\0') {
+		/* NULL password */
+		e_info(authdb_event(request),
+		       "Cached NULL password access");
+		ret = 1;
+	} else if (request->set->cache_verify_password_with_worker) {
+		string_t *str;
+
+		str = t_str_new(128);
+		str_printfa(str, "PASSW\t%u\t", request->passdb->passdb->id);
+		str_append_tabescaped(str, password);
+		str_append_c(str, '\t');
+		str_append_tabescaped(str, cached_pw);
+		str_append_c(str, '\t');
+		auth_request_export(request, str);
+
+		e_debug(authdb_event(request), "cache: "
+			"validating password on worker");
+		auth_request_ref(request);
+		/* Save the extra fields already here, and take a snapshot.
+		   If verification fails, roll back fields. */
+		auth_request_set_fields(request, list + 1, NULL);
+		auth_fields_snapshot(request->fields.extra_fields);
+		auth_worker_call(request->pool, request->fields.user, str_c(str),
+				 passdb_cache_verify_plain_callback, request);
+		return TRUE;
+	} else {
+		scheme = password_get_scheme(&cached_pw);
+		i_assert(scheme != NULL);
+
+		ret = auth_request_password_verify_log(request, password, cached_pw,
+						   scheme, AUTH_SUBSYS_DB,
+						   !(node->last_success || neg_expired));
+
+		if (ret == 0 && (node->last_success || neg_expired)) {
+			/* a) the last authentication was successful. assume
+			   that the password was changed and cache is expired.
+			   b) negative TTL reached, use it for password
+			   mismatches too. */
+			node->last_success = FALSE;
+			return FALSE;
+		}
+	}
+	node->last_success = ret > 0;
+
+	/* save the extra_fields only after we know we're using the
+	   cached data */
+	auth_request_set_fields(request, list + 1, NULL);
+
+	*result_r = ret > 0 ? PASSDB_RESULT_OK :
+		PASSDB_RESULT_PASSWORD_MISMATCH;
+
+	auth_request_verify_plain_callback_finish(*result_r, request);
+	return TRUE;
+}
+
+bool passdb_cache_lookup_credentials(struct auth_request *request,
+				     const char *key, const char **password_r,
+				     const char **scheme_r,
+				     enum passdb_result *result_r,
+				     bool use_expired)
+{
+	const char *value, *const *list;
+	struct auth_cache_node *node;
+	bool neg_expired;
+
+	if (passdb_cache == NULL)
+		return FALSE;
+
+	if (!passdb_cache_lookup(request, key, use_expired,
+				 &node, &value, &neg_expired))
+		return FALSE;
+
+	if (*value == '\0') {
+		/* negative cache entry */
+		*result_r = PASSDB_RESULT_USER_UNKNOWN;
+		*password_r = NULL;
+		*scheme_r = NULL;
+		return TRUE;
+	}
+
+	list = t_strsplit_tabescaped(value);
+	auth_request_set_fields(request, list + 1, NULL);
+
+	*result_r = PASSDB_RESULT_OK;
+	*password_r = *list[0] == '\0' ? NULL : list[0];
+	*scheme_r = password_get_scheme(password_r);
+	i_assert(*scheme_r != NULL || *password_r == NULL);
+	return TRUE;
+}
+
+void passdb_cache_init(const struct auth_settings *set)
+{
+	rlim_t limit;
+
+	if (set->cache_size == 0 || set->cache_ttl == 0)
+		return;
+
+	if (restrict_get_process_size(&limit) == 0 &&
+	    set->cache_size > (uoff_t)limit) {
+		i_warning("auth_cache_size (%"PRIuUOFF_T"M) is higher than "
+			  "process VSZ limit (%"PRIuUOFF_T"M)",
+			  set->cache_size/1024/1024,
+			  (uoff_t)(limit/1024/1024));
+	}
+	passdb_cache = auth_cache_new(set->cache_size, set->cache_ttl,
+				      set->cache_negative_ttl);
+}
+
+void passdb_cache_deinit(void)
+{
+	if (passdb_cache != NULL)
+		auth_cache_free(&passdb_cache);
+}