1 files changed, 595 insertions, 0 deletions

diff --git a/src/tls/tls_scache.c b/src/tls/tls_scache.c
new file mode 100644
index 0000000..dcfd3d0
--- /dev/null
+++ b/src/tls/tls_scache.c
@@ -0,0 +1,595 @@
+/*++
+/* NAME
+/*	tls_scache 3
+/* SUMMARY
+/*	TLS session cache manager
+/* SYNOPSIS
+/*	#include <tls_scache.h>
+/*
+/*	TLS_SCACHE *tls_scache_open(dbname, cache_label, verbose, timeout)
+/*	const char *dbname
+/*	const char *cache_label;
+/*	int	verbose;
+/*	int	timeout;
+/*
+/*	void	tls_scache_close(cache)
+/*	TLS_SCACHE *cache;
+/*
+/*	int	tls_scache_lookup(cache, cache_id, out_session)
+/*	TLS_SCACHE *cache;
+/*	const char *cache_id;
+/*	VSTRING	*out_session;
+/*
+/*	int	tls_scache_update(cache, cache_id, session, session_len)
+/*	TLS_SCACHE *cache;
+/*	const char *cache_id;
+/*	const char *session;
+/*	ssize_t	session_len;
+/*
+/*	int	tls_scache_sequence(cache, first_next, out_cache_id,
+/*				VSTRING *out_session)
+/*	TLS_SCACHE *cache;
+/*	int	first_next;
+/*	char	**out_cache_id;
+/*	VSTRING	*out_session;
+/*
+/*	int	tls_scache_delete(cache, cache_id)
+/*	TLS_SCACHE *cache;
+/*	const char *cache_id;
+/*
+/*	TLS_TICKET_KEY *tls_scache_key(keyname, now, timeout)
+/*	unsigned char *keyname;
+/*	time_t	now;
+/*	int	timeout;
+/*
+/*	TLS_TICKET_KEY *tls_scache_key_rotate(newkey)
+/*	TLS_TICKET_KEY *newkey;
+/* DESCRIPTION
+/*	This module maintains Postfix TLS session cache files.
+/*	each session is stored under a lookup key (hostname or
+/*	session ID).
+/*
+/*	tls_scache_open() opens the specified TLS session cache
+/*	and returns a handle that must be used for subsequent
+/*	access.
+/*
+/*	tls_scache_close() closes the specified TLS session cache
+/*	and releases memory that was allocated by tls_scache_open().
+/*
+/*	tls_scache_lookup() looks up the specified session in the
+/*	specified cache, and applies session timeout restrictions.
+/*	Entries that are too old are silently deleted.
+/*
+/*	tls_scache_update() updates the specified TLS session cache
+/*	with the specified session information.
+/*
+/*	tls_scache_sequence() iterates over the specified TLS session
+/*	cache and either returns the first or next entry that has not
+/*	timed out, or returns no data. Entries that are too old are
+/*	silently deleted. Specify TLS_SCACHE_SEQUENCE_NOTHING as the
+/*	third and last argument to disable saving of cache entry
+/*	content or cache entry ID information. This is useful when
+/*	purging expired entries. A result value of zero means that
+/*	the end of the cache was reached.
+/*
+/*	tls_scache_delete() removes the specified cache entry from
+/*	the specified TLS session cache.
+/*
+/*	tls_scache_key() locates a TLS session ticket key in a 2-element
+/*	in-memory cache.  A null result is returned if no unexpired matching
+/*	key is found.
+/*
+/*	tls_scache_key_rotate() saves a TLS session tickets key in the
+/*	in-memory cache.
+/*
+/*	Arguments:
+/* .IP dbname
+/*	The base name of the session cache file.
+/* .IP cache_label
+/*	A string that is used in logging and error messages.
+/* .IP verbose
+/*	Do verbose logging of cache operations? (zero == no)
+/* .IP timeout
+/*	The time after which a session cache entry is considered too old.
+/* .IP first_next
+/*	One of DICT_SEQ_FUN_FIRST (first cache element) or DICT_SEQ_FUN_NEXT
+/*	(next cache element).
+/* .IP cache_id
+/*	Session cache lookup key.
+/* .IP session
+/*	Storage for session information.
+/* .IP session_len
+/*	The size of the session information in bytes.
+/* .IP out_cache_id
+/* .IP out_session
+/*	Storage for saving the cache_id or session information of the
+/*	current cache entry.
+/*
+/*	Specify TLS_SCACHE_DONT_NEED_CACHE_ID to avoid saving
+/*	the session cache ID of the cache entry.
+/*
+/*	Specify TLS_SCACHE_DONT_NEED_SESSION to avoid
+/*	saving the session information in the cache entry.
+/* .IP keyname
+/*	Is null when requesting the current encryption keys.  Otherwise,
+/*	keyname is a pointer to an array of TLS_TICKET_NAMELEN unsigned
+/*	chars (not NUL terminated) that is an identifier for a key
+/*	previously used to encrypt a session ticket.
+/* .IP now
+/*	Current epoch time passed by caller.
+/* .IP timeout
+/*	TLS session ticket encryption lifetime.
+/* .IP newkey
+/*	TLS session ticket key obtained from tlsmgr(8) to be added to
+ *	internal cache.
+/* DIAGNOSTICS
+/*	These routines terminate with a fatal run-time error
+/*	for unrecoverable database errors. This allows the
+/*	program to restart and reset the database to an
+/*	empty initial state.
+/*
+/*	tls_scache_open() never returns on failure. All other
+/*	functions return non-zero on success, zero when the
+/*	operation could not be completed.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+
+#ifdef USE_TLS
+
+#include <string.h>
+#include <stddef.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <dict.h>
+#include <stringops.h>
+#include <mymalloc.h>
+#include <hex_code.h>
+#include <myflock.h>
+#include <vstring.h>
+#include <timecmp.h>
+
+/* Global library. */
+
+/* TLS library. */
+
+#include <tls_scache.h>
+
+/* Application-specific. */
+
+ /*
+  * Session cache entry format.
+  */
+typedef struct {
+    time_t  timestamp;			/* time when saved */
+    char    session[1];			/* actually a bunch of bytes */
+} TLS_SCACHE_ENTRY;
+
+static TLS_TICKET_KEY *keys[2];
+
+ /*
+  * SLMs.
+  */
+#define STR(x)		vstring_str(x)
+#define LEN(x)		VSTRING_LEN(x)
+
+/* tls_scache_encode - encode TLS session cache entry */
+
+static VSTRING *tls_scache_encode(TLS_SCACHE *cp, const char *cache_id,
+				          const char *session,
+				          ssize_t session_len)
+{
+    TLS_SCACHE_ENTRY *entry;
+    VSTRING *hex_data;
+    ssize_t binary_data_len;
+
+    /*
+     * Assemble the TLS session cache entry.
+     * 
+     * We could eliminate some copying by using incremental encoding, but
+     * sessions are so small that it really does not matter.
+     */
+    binary_data_len = session_len + offsetof(TLS_SCACHE_ENTRY, session);
+    entry = (TLS_SCACHE_ENTRY *) mymalloc(binary_data_len);
+    entry->timestamp = time((time_t *) 0);
+    memcpy(entry->session, session, session_len);
+
+    /*
+     * Encode the TLS session cache entry.
+     */
+    hex_data = vstring_alloc(2 * binary_data_len + 1);
+    hex_encode(hex_data, (char *) entry, binary_data_len);
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("write %s TLS cache entry %s: time=%ld [data %ld bytes]",
+		 cp->cache_label, cache_id, (long) entry->timestamp,
+		 (long) session_len);
+
+    /*
+     * Clean up.
+     */
+    myfree((void *) entry);
+
+    return (hex_data);
+}
+
+/* tls_scache_decode - decode TLS session cache entry */
+
+static int tls_scache_decode(TLS_SCACHE *cp, const char *cache_id,
+			         const char *hex_data, ssize_t hex_data_len,
+			             VSTRING *out_session)
+{
+    TLS_SCACHE_ENTRY *entry;
+    VSTRING *bin_data;
+
+    /*
+     * Sanity check.
+     */
+    if (hex_data_len < 2 * (offsetof(TLS_SCACHE_ENTRY, session))) {
+	msg_warn("%s TLS cache: truncated entry for %s: %.100s",
+		 cp->cache_label, cache_id, hex_data);
+	return (0);
+    }
+
+    /*
+     * Disassemble the TLS session cache entry.
+     * 
+     * No early returns or we have a memory leak.
+     */
+#define FREE_AND_RETURN(ptr, x) { vstring_free(ptr); return (x); }
+
+    bin_data = vstring_alloc(hex_data_len / 2 + 1);
+    if (hex_decode(bin_data, hex_data, hex_data_len) == 0) {
+	msg_warn("%s TLS cache: malformed entry for %s: %.100s",
+		 cp->cache_label, cache_id, hex_data);
+	FREE_AND_RETURN(bin_data, 0);
+    }
+    entry = (TLS_SCACHE_ENTRY *) STR(bin_data);
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("read %s TLS cache entry %s: time=%ld [data %ld bytes]",
+		 cp->cache_label, cache_id, (long) entry->timestamp,
+	      (long) (LEN(bin_data) - offsetof(TLS_SCACHE_ENTRY, session)));
+
+    /*
+     * Other mandatory restrictions.
+     */
+    if (entry->timestamp + cp->timeout < time((time_t *) 0))
+	FREE_AND_RETURN(bin_data, 0);
+
+    /*
+     * Optional output.
+     */
+    if (out_session != 0)
+	vstring_memcpy(out_session, entry->session,
+		       LEN(bin_data) - offsetof(TLS_SCACHE_ENTRY, session));
+
+    /*
+     * Clean up.
+     */
+    FREE_AND_RETURN(bin_data, 1);
+}
+
+/* tls_scache_lookup - load session from cache */
+
+int     tls_scache_lookup(TLS_SCACHE *cp, const char *cache_id,
+			          VSTRING *session)
+{
+    const char *hex_data;
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("lookup %s session id=%s", cp->cache_label, cache_id);
+
+    /*
+     * Initialize. Don't leak data.
+     */
+    if (session)
+	VSTRING_RESET(session);
+
+    /*
+     * Search the cache database.
+     */
+    if ((hex_data = dict_get(cp->db, cache_id)) == 0)
+	return (0);
+
+    /*
+     * Decode entry and delete if expired or malformed.
+     */
+    if (tls_scache_decode(cp, cache_id, hex_data, strlen(hex_data),
+			  session) == 0) {
+	tls_scache_delete(cp, cache_id);
+	return (0);
+    } else {
+	return (1);
+    }
+}
+
+/* tls_scache_update - save session to cache */
+
+int     tls_scache_update(TLS_SCACHE *cp, const char *cache_id,
+			          const char *buf, ssize_t len)
+{
+    VSTRING *hex_data;
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("put %s session id=%s [data %ld bytes]",
+		 cp->cache_label, cache_id, (long) len);
+
+    /*
+     * Encode the cache entry.
+     */
+    hex_data = tls_scache_encode(cp, cache_id, buf, len);
+
+    /*
+     * Store the cache entry.
+     * 
+     * XXX Berkeley DB supports huge database keys and values. SDBM seems to
+     * have a finite limit, and DBM simply can't be used at all.
+     */
+    dict_put(cp->db, cache_id, STR(hex_data));
+
+    /*
+     * Clean up.
+     */
+    vstring_free(hex_data);
+
+    return (1);
+}
+
+/* tls_scache_sequence - get first/next TLS session cache entry */
+
+int     tls_scache_sequence(TLS_SCACHE *cp, int first_next,
+			            char **out_cache_id,
+			            VSTRING *out_session)
+{
+    const char *member;
+    const char *value;
+    char   *saved_cursor;
+    int     found_entry;
+    int     keep_entry;
+    char   *saved_member;
+
+    /*
+     * XXX Deleting entries while enumerating a map can he tricky. Some map
+     * types have a concept of cursor and support a "delete the current
+     * element" operation. Some map types without cursors don't behave well
+     * when the current first/next entry is deleted (example: with Berkeley
+     * DB < 2, the "next" operation produces garbage). To avoid trouble, we
+     * delete an expired entry after advancing the current first/next
+     * position beyond it, and ignore client requests to delete the current
+     * entry.
+     */
+
+    /*
+     * Find the first or next database entry. Activate the passivated entry
+     * and check the time stamp. Schedule the entry for deletion if it is too
+     * old.
+     * 
+     * Save the member (cache id) so that it will not be clobbered by the
+     * tls_scache_lookup() call below.
+     */
+    found_entry = (dict_seq(cp->db, first_next, &member, &value) == 0);
+    if (found_entry) {
+	keep_entry = tls_scache_decode(cp, member, value, strlen(value),
+				       out_session);
+	if (keep_entry && out_cache_id)
+	    *out_cache_id = mystrdup(member);
+	saved_member = mystrdup(member);
+    }
+
+    /*
+     * Delete behind. This is a no-op if an expired cache entry was updated
+     * in the mean time. Use the saved lookup criteria so that the "delete
+     * behind" operation works as promised.
+     * 
+     * The delete-behind strategy assumes that all updates are made by a single
+     * process. Otherwise, delete-behind may remove an entry that was updated
+     * after it was scheduled for deletion.
+     */
+    if (cp->flags & TLS_SCACHE_FLAG_DEL_SAVED_CURSOR) {
+	cp->flags &= ~TLS_SCACHE_FLAG_DEL_SAVED_CURSOR;
+	saved_cursor = cp->saved_cursor;
+	cp->saved_cursor = 0;
+	tls_scache_lookup(cp, saved_cursor, (VSTRING *) 0);
+	myfree(saved_cursor);
+    }
+
+    /*
+     * Otherwise, clean up if this is not the first iteration.
+     */
+    else {
+	if (cp->saved_cursor)
+	    myfree(cp->saved_cursor);
+	cp->saved_cursor = 0;
+    }
+
+    /*
+     * Protect the current first/next entry against explicit or implied
+     * client delete requests, and schedule a bad or expired entry for
+     * deletion. Save the lookup criteria so that the "delete behind"
+     * operation will work as promised.
+     */
+    if (found_entry) {
+	cp->saved_cursor = saved_member;
+	if (keep_entry == 0)
+	    cp->flags |= TLS_SCACHE_FLAG_DEL_SAVED_CURSOR;
+    }
+    return (found_entry);
+}
+
+/* tls_scache_delete - delete session from cache */
+
+int     tls_scache_delete(TLS_SCACHE *cp, const char *cache_id)
+{
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("delete %s session id=%s", cp->cache_label, cache_id);
+
+    /*
+     * Do it, unless we would delete the current first/next entry. Some map
+     * types don't have cursors, and some of those don't behave when the
+     * "current" entry is deleted.
+     */
+    return ((cp->saved_cursor != 0 && strcmp(cp->saved_cursor, cache_id) == 0)
+	    || dict_del(cp->db, cache_id) == 0);
+}
+
+/* tls_scache_open - open TLS session cache file */
+
+TLS_SCACHE *tls_scache_open(const char *dbname, const char *cache_label,
+			            int verbose, int timeout)
+{
+    TLS_SCACHE *cp;
+    DICT   *dict;
+
+    /*
+     * Logging.
+     */
+    if (verbose)
+	msg_info("open %s TLS cache %s", cache_label, dbname);
+
+    /*
+     * Open the dictionary with O_TRUNC, so that we never have to worry about
+     * opening a damaged file after some process terminated abnormally.
+     */
+#ifdef SINGLE_UPDATER
+#define DICT_FLAGS (DICT_FLAG_DUP_REPLACE | DICT_FLAG_OPEN_LOCK \
+		    | DICT_FLAG_UTF8_REQUEST)
+#else
+#define DICT_FLAGS \
+	(DICT_FLAG_DUP_REPLACE | DICT_FLAG_LOCK | DICT_FLAG_SYNC_UPDATE \
+	 | DICT_FLAG_UTF8_REQUEST)
+#endif
+
+    dict = dict_open(dbname, O_RDWR | O_CREAT | O_TRUNC, DICT_FLAGS);
+
+    /*
+     * Sanity checks.
+     */
+    if (dict->update == 0)
+	msg_fatal("dictionary %s does not support update operations", dbname);
+    if (dict->delete == 0)
+	msg_fatal("dictionary %s does not support delete operations", dbname);
+    if (dict->sequence == 0)
+	msg_fatal("dictionary %s does not support sequence operations", dbname);
+
+    /*
+     * Create the TLS_SCACHE object.
+     */
+    cp = (TLS_SCACHE *) mymalloc(sizeof(*cp));
+    cp->flags = 0;
+    cp->db = dict;
+    cp->cache_label = mystrdup(cache_label);
+    cp->verbose = verbose;
+    cp->timeout = timeout;
+    cp->saved_cursor = 0;
+
+    return (cp);
+}
+
+/* tls_scache_close - close TLS session cache file */
+
+void    tls_scache_close(TLS_SCACHE *cp)
+{
+
+    /*
+     * Logging.
+     */
+    if (cp->verbose)
+	msg_info("close %s TLS cache %s", cp->cache_label, cp->db->name);
+
+    /*
+     * Destroy the TLS_SCACHE object.
+     */
+    dict_close(cp->db);
+    myfree(cp->cache_label);
+    if (cp->saved_cursor)
+	myfree(cp->saved_cursor);
+    myfree((void *) cp);
+}
+
+/* tls_scache_key - find session ticket key for given key name */
+
+TLS_TICKET_KEY *tls_scache_key(unsigned char *keyname, time_t now, int timeout)
+{
+    int     i;
+
+    /*
+     * The keys array contains 2 elements, the current signing key and the
+     * previous key.
+     * 
+     * When name == 0 we are issuing a ticket, otherwise decrypting an existing
+     * ticket with the given key name.  For new tickets we always use the
+     * current key if unexpired.  For existing tickets, we use either the
+     * current or previous key with a validation expiration that is timeout
+     * longer than the signing expiration.
+     */
+    if (keyname) {
+	for (i = 0; i < 2 && keys[i]; ++i) {
+	    if (memcmp(keyname, keys[i]->name, TLS_TICKET_NAMELEN) == 0) {
+		if (timecmp(keys[i]->tout + timeout, now) > 0)
+		    return (keys[i]);
+		break;
+	    }
+	}
+    } else if (keys[0]) {
+	if (timecmp(keys[0]->tout, now) > 0)
+	    return (keys[0]);
+    }
+    return (0);
+}
+
+/* tls_scache_key_rotate - rotate session ticket keys */
+
+TLS_TICKET_KEY *tls_scache_key_rotate(TLS_TICKET_KEY *newkey)
+{
+
+    /*
+     * Allocate or re-use storage of retired key, then overwrite it, since
+     * caller's key data is ephemeral.
+     */
+    if (keys[1] == 0)
+	keys[1] = (TLS_TICKET_KEY *) mymalloc(sizeof(*newkey));
+    *keys[1] = *newkey;
+    newkey = keys[1];
+
+    /*
+     * Rotate if required, ensuring that the keys are sorted by expiration
+     * time with keys[0] expiring last.
+     */
+    if (keys[0] == 0 || keys[0]->tout < keys[1]->tout) {
+	keys[1] = keys[0];
+	keys[0] = newkey;
+    }
+    return (newkey);
+}
+
+#endif