1 files changed, 272 insertions, 0 deletions

diff --git a/src/smtp/smtp_sasl_auth_cache.c b/src/smtp/smtp_sasl_auth_cache.c
new file mode 100644
index 0000000..f3104ca
--- /dev/null
+++ b/src/smtp/smtp_sasl_auth_cache.c
@@ -0,0 +1,272 @@
+/*++
+/* NAME
+/*	smtp_sasl_auth_cache 3
+/* SUMMARY
+/*	Postfix SASL authentication reply cache
+/* SYNOPSIS
+/*	#include "smtp.h"
+/*	#include "smtp_sasl_auth_cache.h"
+/*
+/*	SMTP_SASL_AUTH_CACHE *smtp_sasl_auth_cache_init(map, ttl)
+/*	const char *map
+/*	int	ttl;
+/*
+/*	void	smtp_sasl_auth_cache_store(auth_cache, session, resp)
+/*	SMTP_SASL_AUTH_CACHE *auth_cache;
+/*	const SMTP_SESSION *session;
+/*	const SMTP_RESP *resp;
+/*
+/*	int	smtp_sasl_auth_cache_find(auth_cache, session)
+/*	SMTP_SASL_AUTH_CACHE *auth_cache;
+/*	const SMTP_SESSION *session;
+/*
+/*	char	*smtp_sasl_auth_cache_dsn(auth_cache)
+/*	SMTP_SASL_AUTH_CACHE *auth_cache;
+/*
+/*	char	*smtp_sasl_auth_cache_text(auth_cache)
+/*	SMTP_SASL_AUTH_CACHE *auth_cache;
+/* DESCRIPTION
+/*	This module maintains a cache of SASL authentication server replies.
+/*	This can be used to avoid repeated login failure errors.
+/*
+/*	smtp_sasl_auth_cache_init() opens or creates the named cache.
+/*
+/*	smtp_sasl_auth_cache_store() stores information about a
+/*	SASL login attempt together with the server status and
+/*	complete response.
+/*
+/*	smtp_sasl_auth_cache_find() returns non-zero when a cache
+/*	entry exists for the given host, username and password.
+/*
+/*	smtp_sasl_auth_cache_dsn() and smtp_sasl_auth_cache_text()
+/*	return the status and complete server response as found
+/*	with smtp_sasl_auth_cache_find().
+/*
+/*	Arguments:
+/* .IP map
+/*	Lookup table name. The name must be singular and must start
+/*	with "proxy:".
+/* .IP ttl
+/*	The time after which a cache entry is considered expired.
+/* .IP session
+/*	Session context.
+/* .IP resp
+/*	Remote SMTP server response, to be stored into the cache.
+/* DIAGNOSTICS
+/*	All errors are fatal.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Original author:
+/*	Keean Schupke
+/*	Fry-IT Ltd.
+/*
+/*	Updated by:
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+ /*
+  * System library.
+  */
+#include <sys_defs.h>
+
+ /*
+  * Utility library
+  */
+#include <msg.h>
+#include <mymalloc.h>
+#include <stringops.h>
+#include <base64_code.h>
+#include <dict.h>
+
+ /*
+  * Global library
+  */
+#include <dsn_util.h>
+#include <dict_proxy.h>
+
+ /*
+  * Application-specific
+  */
+#include "smtp.h"
+#include "smtp_sasl_auth_cache.h"
+
+ /*
+  * XXX This feature stores passwords, so we must mask them with a strong
+  * cryptographic hash. This requires OpenSSL support.
+  * 
+  * XXX It would be even better if the stored hash were salted.
+  */
+#ifdef HAVE_SASL_AUTH_CACHE
+
+/* smtp_sasl_auth_cache_init - per-process initialization (pre jail) */
+
+SMTP_SASL_AUTH_CACHE *smtp_sasl_auth_cache_init(const char *map, int ttl)
+{
+    const char *myname = "smtp_sasl_auth_cache_init";
+    SMTP_SASL_AUTH_CACHE *auth_cache;
+
+    /*
+     * Sanity checks.
+     */
+#define HAS_MULTIPLE_VALUES(s) ((s)[strcspn((s),  CHARS_COMMA_SP)] != 0)
+
+    if (*map == 0)
+	msg_panic("%s: empty SASL authentication cache name", myname);
+    if (ttl < 0)
+	msg_panic("%s: bad SASL authentication cache ttl: %d", myname, ttl);
+    if (HAS_MULTIPLE_VALUES(map))
+	msg_fatal("SASL authentication cache name \"%s\" "
+		  "contains multiple values", map);
+
+    /*
+     * XXX To avoid multiple writers the map needs to be maintained by the
+     * proxywrite service. We would like to have a DICT_FLAG_REQ_PROXY flag
+     * so that the library can enforce this, but that requires moving the
+     * dict_proxy module one level down in the build dependency hierarchy.
+     */
+#define CACHE_DICT_OPEN_FLAGS \
+	(DICT_FLAG_DUP_REPLACE | DICT_FLAG_SYNC_UPDATE | DICT_FLAG_UTF8_REQUEST)
+#define PROXY_COLON	DICT_TYPE_PROXY ":"
+#define PROXY_COLON_LEN	(sizeof(PROXY_COLON) - 1)
+
+    if (strncmp(map, PROXY_COLON, PROXY_COLON_LEN) != 0)
+	msg_fatal("SASL authentication cache name \"%s\" must start with \""
+		  PROXY_COLON, map);
+
+    auth_cache = (SMTP_SASL_AUTH_CACHE *) mymalloc(sizeof(*auth_cache));
+    auth_cache->dict = dict_open(map, O_CREAT | O_RDWR, CACHE_DICT_OPEN_FLAGS);
+    auth_cache->ttl = ttl;
+    auth_cache->dsn = mystrdup("");
+    auth_cache->text = mystrdup("");
+    return (auth_cache);
+}
+
+ /*
+  * Each cache lookup key contains a server host name and user name. Each
+  * cache value contains a time stamp, a hashed password, and the server
+  * response. With this organization, we don't have to worry about cache
+  * pollution, because we can detect if a cache entry has expired, or if the
+  * password has changed.
+  */
+
+/* smtp_sasl_auth_cache_make_key - format auth failure cache lookup key */
+
+static char *smtp_sasl_auth_cache_make_key(const char *host, const char *user)
+{
+    VSTRING *buf = vstring_alloc(100);
+
+    vstring_sprintf(buf, "%s;%s", host, user);
+    return (vstring_export(buf));
+}
+
+/* smtp_sasl_auth_cache_make_pass - hash the auth failure cache password */
+
+static char *smtp_sasl_auth_cache_make_pass(const char *password)
+{
+    VSTRING *buf = vstring_alloc(2 * SHA_DIGEST_LENGTH);
+
+    base64_encode(buf, (const char *) SHA1((const unsigned char *) password,
+					   strlen(password), 0),
+		  SHA_DIGEST_LENGTH);
+    return (vstring_export(buf));
+}
+
+/* smtp_sasl_auth_cache_make_value - format auth failure cache value */
+
+static char *smtp_sasl_auth_cache_make_value(const char *password,
+					             const char *dsn,
+					             const char *rep_str)
+{
+    VSTRING *val_buf = vstring_alloc(100);
+    char   *pwd_hash;
+    unsigned long now = (unsigned long) time((time_t *) 0);
+
+    pwd_hash = smtp_sasl_auth_cache_make_pass(password);
+    vstring_sprintf(val_buf, "%lu;%s;%s;%s", now, pwd_hash, dsn, rep_str);
+    myfree(pwd_hash);
+    return (vstring_export(val_buf));
+}
+
+/* smtp_sasl_auth_cache_valid_value - validate auth failure cache value */
+
+static int smtp_sasl_auth_cache_valid_value(SMTP_SASL_AUTH_CACHE *auth_cache,
+					            const char *entry,
+					            const char *password)
+{
+    ssize_t len = strlen(entry);
+    char   *cache_hash = mymalloc(len);
+    char   *curr_hash;
+    unsigned long now = (unsigned long) time((time_t *) 0);
+    unsigned long time_stamp;
+    int     valid;
+
+    auth_cache->dsn = myrealloc(auth_cache->dsn, len);
+    auth_cache->text = myrealloc(auth_cache->text, len);
+
+    if (sscanf(entry, "%lu;%[^;];%[^;];%[^\n]", &time_stamp, cache_hash,
+	       auth_cache->dsn, auth_cache->text) != 4
+	|| !dsn_valid(auth_cache->dsn)) {
+	msg_warn("bad smtp_sasl_auth_cache entry: %.100s", entry);
+	valid = 0;
+    } else if (time_stamp + auth_cache->ttl < now) {
+	valid = 0;
+    } else {
+	curr_hash = smtp_sasl_auth_cache_make_pass(password);
+	valid = (strcmp(cache_hash, curr_hash) == 0);
+	myfree(curr_hash);
+    }
+    myfree(cache_hash);
+    return (valid);
+}
+
+/* smtp_sasl_auth_cache_find - search auth failure cache */
+
+int     smtp_sasl_auth_cache_find(SMTP_SASL_AUTH_CACHE *auth_cache,
+				          const SMTP_SESSION *session)
+{
+    SMTP_ITERATOR *iter = session->iterator;
+    char   *key;
+    const char *entry;
+    int     valid = 0;
+
+    key = smtp_sasl_auth_cache_make_key(STR(iter->host), session->sasl_username);
+    if ((entry = dict_get(auth_cache->dict, key)) != 0)
+	if ((valid = smtp_sasl_auth_cache_valid_value(auth_cache, entry,
+						session->sasl_passwd)) == 0)
+	    /* Remove expired, password changed, or malformed cache entry. */
+	    if (dict_del(auth_cache->dict, key) != 0)
+		msg_warn("SASL auth failure map %s: entry not deleted: %s",
+			 auth_cache->dict->name, key);
+    if (auth_cache->dict->error)
+	msg_warn("SASL auth failure map %s: lookup failed for %s",
+		 auth_cache->dict->name, key);
+    myfree(key);
+    return (valid);
+}
+
+/* smtp_sasl_auth_cache_store - update auth failure cache */
+
+void    smtp_sasl_auth_cache_store(SMTP_SASL_AUTH_CACHE *auth_cache,
+				           const SMTP_SESSION *session,
+				           const SMTP_RESP *resp)
+{
+    SMTP_ITERATOR *iter = session->iterator;
+    char   *key;
+    char   *value;
+
+    key = smtp_sasl_auth_cache_make_key(STR(iter->host), session->sasl_username);
+    value = smtp_sasl_auth_cache_make_value(session->sasl_passwd,
+					    resp->dsn, resp->str);
+    dict_put(auth_cache->dict, key, value);
+
+    myfree(value);
+    myfree(key);
+}
+
+#endif