Adding upstream version 3.7.10.upstream/3.7.10

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1115 insertions, 0 deletions

diff --git a/src/tlsmgr/tlsmgr.c b/src/tlsmgr/tlsmgr.c
new file mode 100644
index 0000000..28ca961
--- /dev/null
+++ b/src/tlsmgr/tlsmgr.c
@@ -0,0 +1,1115 @@
+/*++
+/* NAME
+/*	tlsmgr 8
+/* SUMMARY
+/*	Postfix TLS session cache and PRNG manager
+/* SYNOPSIS
+/*	\fBtlsmgr\fR [generic Postfix daemon options]
+/* DESCRIPTION
+/*	The \fBtlsmgr\fR(8) manages the Postfix TLS session caches.
+/*	It stores and retrieves cache entries on request by
+/*	\fBsmtpd\fR(8) and \fBsmtp\fR(8) processes, and periodically
+/*	removes entries that have expired.
+/*
+/*	The \fBtlsmgr\fR(8) also manages the PRNG (pseudo random number
+/*	generator) pool. It answers queries by the \fBsmtpd\fR(8)
+/*	and \fBsmtp\fR(8)
+/*	processes to seed their internal PRNG pools.
+/*
+/*	The \fBtlsmgr\fR(8)'s PRNG pool is initially seeded from
+/*	an external source (EGD, /dev/urandom, or regular file).
+/*	It is updated at configurable pseudo-random intervals with
+/*	data from the external source. It is updated periodically
+/*	with data from TLS session cache entries and with the time
+/*	of day, and is updated with the time of day whenever a
+/*	process requests \fBtlsmgr\fR(8) service.
+/*
+/*	The \fBtlsmgr\fR(8) saves the PRNG state to an exchange file
+/*	periodically and when the process terminates, and reads
+/*	the exchange file when initializing its PRNG.
+/* SECURITY
+/* .ad
+/* .fi
+/*	The \fBtlsmgr\fR(8) is not security-sensitive. The code that maintains
+/*	the external and internal PRNG pools does not "trust" the
+/*	data that it manipulates, and the code that maintains the
+/*	TLS session cache does not touch the contents of the cached
+/*	entries, except for seeding its internal PRNG pool.
+/*
+/*	The \fBtlsmgr\fR(8) can be run chrooted and with reduced privileges.
+/*	At process startup it connects to the entropy source and
+/*	exchange file, and creates or truncates the optional TLS
+/*	session cache files.
+/*
+/*	With Postfix version 2.5 and later, the \fBtlsmgr\fR(8) no
+/*	longer uses root privileges when opening cache files. These
+/*	files should now be stored under the Postfix-owned
+/*	\fBdata_directory\fR.  As a migration aid, an attempt to
+/*	open a cache file under a non-Postfix directory is redirected
+/*	to the Postfix-owned \fBdata_directory\fR, and a warning
+/*	is logged.
+/* DIAGNOSTICS
+/*	Problems and transactions are logged to \fBsyslogd\fR(8)
+/*	or \fBpostlogd\fR(8).
+/* BUGS
+/*	There is no automatic means to limit the number of entries in the
+/*	TLS session caches and/or the size of the TLS cache files.
+/* CONFIGURATION PARAMETERS
+/* .ad
+/* .fi
+/*	Changes to \fBmain.cf\fR are not picked up automatically,
+/*	because \fBtlsmgr\fR(8) is a persistent processes.  Use the
+/*	command "\fBpostfix reload\fR" after a configuration change.
+/*
+/*	The text below provides only a parameter summary. See
+/*	\fBpostconf\fR(5) for more details including examples.
+/* TLS SESSION CACHE
+/* .ad
+/* .fi
+/* .IP "\fBlmtp_tls_loglevel (0)\fR"
+/*	The LMTP-specific version of the smtp_tls_loglevel
+/*	configuration parameter.
+/* .IP "\fBlmtp_tls_session_cache_database (empty)\fR"
+/*	The LMTP-specific version of the smtp_tls_session_cache_database
+/*	configuration parameter.
+/* .IP "\fBlmtp_tls_session_cache_timeout (3600s)\fR"
+/*	The LMTP-specific version of the smtp_tls_session_cache_timeout
+/*	configuration parameter.
+/* .IP "\fBsmtp_tls_loglevel (0)\fR"
+/*	Enable additional Postfix SMTP client logging of TLS activity.
+/* .IP "\fBsmtp_tls_session_cache_database (empty)\fR"
+/*	Name of the file containing the optional Postfix SMTP client
+/*	TLS session cache.
+/* .IP "\fBsmtp_tls_session_cache_timeout (3600s)\fR"
+/*	The expiration time of Postfix SMTP client TLS session cache
+/*	information.
+/* .IP "\fBsmtpd_tls_loglevel (0)\fR"
+/*	Enable additional Postfix SMTP server logging of TLS activity.
+/* .IP "\fBsmtpd_tls_session_cache_database (empty)\fR"
+/*	Name of the file containing the optional Postfix SMTP server
+/*	TLS session cache.
+/* .IP "\fBsmtpd_tls_session_cache_timeout (3600s)\fR"
+/*	The expiration time of Postfix SMTP server TLS session cache
+/*	information.
+/* PSEUDO RANDOM NUMBER GENERATOR
+/* .ad
+/* .fi
+/* .IP "\fBtls_random_source (see 'postconf -d' output)\fR"
+/*	The external entropy source for the in-memory \fBtlsmgr\fR(8) pseudo
+/*	random number generator (PRNG) pool.
+/* .IP "\fBtls_random_bytes (32)\fR"
+/*	The number of bytes that \fBtlsmgr\fR(8) reads from $tls_random_source
+/*	when (re)seeding the in-memory pseudo random number generator (PRNG)
+/*	pool.
+/* .IP "\fBtls_random_exchange_name (see 'postconf -d' output)\fR"
+/*	Name of the pseudo random number generator (PRNG) state file
+/*	that is maintained by \fBtlsmgr\fR(8).
+/* .IP "\fBtls_random_prng_update_period (3600s)\fR"
+/*	The time between attempts by \fBtlsmgr\fR(8) to save the state of
+/*	the pseudo random number generator (PRNG) to the file specified
+/*	with $tls_random_exchange_name.
+/* .IP "\fBtls_random_reseed_period (3600s)\fR"
+/*	The maximal time between attempts by \fBtlsmgr\fR(8) to re-seed the
+/*	in-memory pseudo random number generator (PRNG) pool from external
+/*	sources.
+/* MISCELLANEOUS CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
+/*	The default location of the Postfix main.cf and master.cf
+/*	configuration files.
+/* .IP "\fBdata_directory (see 'postconf -d' output)\fR"
+/*	The directory with Postfix-writable data files (for example:
+/*	caches, pseudo-random numbers).
+/* .IP "\fBdaemon_timeout (18000s)\fR"
+/*	How much time a Postfix daemon process may take to handle a
+/*	request before it is terminated by a built-in watchdog timer.
+/* .IP "\fBprocess_id (read-only)\fR"
+/*	The process ID of a Postfix command or daemon process.
+/* .IP "\fBprocess_name (read-only)\fR"
+/*	The process name of a Postfix command or daemon process.
+/* .IP "\fBsyslog_facility (mail)\fR"
+/*	The syslog facility of Postfix logging.
+/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
+/*	A prefix that is prepended to the process name in syslog
+/*	records, so that, for example, "smtpd" becomes "prefix/smtpd".
+/* .PP
+/*	Available in Postfix 3.3 and later:
+/* .IP "\fBservice_name (read-only)\fR"
+/*	The master.cf service name of a Postfix daemon process.
+/* SEE ALSO
+/*	smtp(8), Postfix SMTP client
+/*	smtpd(8), Postfix SMTP server
+/*	postconf(5), configuration parameters
+/*	master(5), generic daemon options
+/*	master(8), process manager
+/*	postlogd(8), Postfix logging
+/*	syslogd(8), system logging
+/* README FILES
+/* .ad
+/* .fi
+/*	Use "\fBpostconf readme_directory\fR" or
+/*	"\fBpostconf html_directory\fR" to locate this information.
+/* .na
+/* .nf
+/*	TLS_README, Postfix TLS configuration and operation
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* HISTORY
+/*	This service was introduced with Postfix version 2.2.
+/* AUTHOR(S)
+/*	Lutz Jaenicke
+/*	BTU Cottbus
+/*	Allgemeine Elektrotechnik
+/*	Universitaetsplatz 3-4
+/*	D-03044 Cottbus, Germany
+/*
+/*	Adapted by:
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>			/* gettimeofday, not POSIX */
+#include <limits.h>
+
+#ifndef UCHAR_MAX
+#define UCHAR_MAX 0xff
+#endif
+
+/* OpenSSL library. */
+
+#ifdef USE_TLS
+#include <openssl/rand.h>		/* For the PRNG */
+#endif
+
+/* Utility library. */
+
+#include <msg.h>
+#include <events.h>
+#include <stringops.h>
+#include <mymalloc.h>
+#include <iostuff.h>
+#include <vstream.h>
+#include <vstring.h>
+#include <vstring_vstream.h>
+#include <attr.h>
+#include <set_eugid.h>
+#include <htable.h>
+#include <warn_stat.h>
+
+/* Global library. */
+
+#include <mail_conf.h>
+#include <mail_params.h>
+#include <mail_version.h>
+#include <mail_proto.h>
+#include <data_redirect.h>
+
+/* Master process interface. */
+
+#include <master_proto.h>
+#include <mail_server.h>
+
+/* TLS library. */
+
+#ifdef USE_TLS
+#include <tls_mgr.h>
+#define TLS_INTERNAL
+#include <tls.h>			/* TLS_MGR_SCACHE_<type> */
+#include <tls_prng.h>
+#include <tls_scache.h>
+
+/* Application-specific. */
+
+ /*
+  * Tunables.
+  */
+char   *var_tls_rand_source;
+int     var_tls_rand_bytes;
+int     var_tls_reseed_period;
+int     var_tls_prng_exch_period;
+char   *var_smtpd_tls_loglevel;
+char   *var_smtpd_tls_scache_db;
+int     var_smtpd_tls_scache_timeout;
+char   *var_smtp_tls_loglevel;
+char   *var_smtp_tls_scache_db;
+int     var_smtp_tls_scache_timeout;
+char   *var_lmtp_tls_loglevel;
+char   *var_lmtp_tls_scache_db;
+int     var_lmtp_tls_scache_timeout;
+char   *var_tls_rand_exch_name;
+
+ /*
+  * Bound the time that we are willing to wait for an I/O operation. This
+  * produces better error messages than waiting until the watchdog timer
+  * kills the process.
+  */
+#define TLS_MGR_TIMEOUT	10
+
+ /*
+  * State for updating the PRNG exchange file.
+  */
+static TLS_PRNG_SRC *rand_exch;
+
+ /*
+  * State for seeding the internal PRNG from external source.
+  */
+static TLS_PRNG_SRC *rand_source_dev;
+static TLS_PRNG_SRC *rand_source_egd;
+static TLS_PRNG_SRC *rand_source_file;
+
+ /*
+  * The external entropy source type is encoded in the source name. The
+  * obvious alternative is to have separate configuration parameters per
+  * source type, so that one process can query multiple external sources.
+  */
+#define DEV_PREF "dev:"
+#define DEV_PREF_LEN (sizeof((DEV_PREF)) - 1)
+#define DEV_PATH(dev) ((dev) + EGD_PREF_LEN)
+
+#define EGD_PREF "egd:"
+#define EGD_PREF_LEN (sizeof((EGD_PREF)) - 1)
+#define EGD_PATH(egd) ((egd) + EGD_PREF_LEN)
+
+ /*
+  * State for TLS session caches.
+  */
+typedef struct {
+    char   *cache_label;		/* cache short-hand name */
+    TLS_SCACHE *cache_info;		/* cache handle */
+    int     cache_active;		/* cache status */
+    char  **cache_db;			/* main.cf parameter value */
+    const char *log_param;		/* main.cf parameter name */
+    char  **log_level;			/* main.cf parameter value */
+    int    *cache_timeout;		/* main.cf parameter value */
+} TLSMGR_SCACHE;
+
+static TLSMGR_SCACHE cache_table[] = {
+    TLS_MGR_SCACHE_SMTPD, 0, 0, &var_smtpd_tls_scache_db,
+    VAR_SMTPD_TLS_LOGLEVEL,
+    &var_smtpd_tls_loglevel, &var_smtpd_tls_scache_timeout,
+    TLS_MGR_SCACHE_SMTP, 0, 0, &var_smtp_tls_scache_db,
+    VAR_SMTP_TLS_LOGLEVEL,
+    &var_smtp_tls_loglevel, &var_smtp_tls_scache_timeout,
+    TLS_MGR_SCACHE_LMTP, 0, 0, &var_lmtp_tls_scache_db,
+    VAR_LMTP_TLS_LOGLEVEL,
+    &var_lmtp_tls_loglevel, &var_lmtp_tls_scache_timeout,
+    0,
+};
+
+#define	smtpd_cache	(cache_table[0])
+
+ /*
+  * SLMs.
+  */
+#define STR(x)		vstring_str(x)
+#define LEN(x)		VSTRING_LEN(x)
+#define STREQ(x, y)	(strcmp((x), (y)) == 0)
+
+/* tlsmgr_prng_exch_event - update PRNG exchange file */
+
+static void tlsmgr_prng_exch_event(int unused_event, void *dummy)
+{
+    const char *myname = "tlsmgr_prng_exch_event";
+    unsigned char randbyte;
+    int     next_period;
+    struct stat st;
+
+    if (msg_verbose)
+	msg_info("%s: update PRNG exchange file", myname);
+
+    /*
+     * Sanity check. If the PRNG exchange file was removed, there is no point
+     * updating it further. Restart the process and update the new file.
+     */
+    if (fstat(rand_exch->fd, &st) < 0)
+	msg_fatal("cannot fstat() the PRNG exchange file: %m");
+    if (st.st_nlink == 0) {
+	msg_warn("PRNG exchange file was removed -- exiting to reopen");
+	sleep(1);
+	exit(0);
+    }
+    tls_prng_exch_update(rand_exch);
+
+    /*
+     * Make prediction difficult for outsiders and calculate the time for the
+     * next execution randomly.
+     */
+    RAND_bytes(&randbyte, 1);
+    next_period = (var_tls_prng_exch_period * randbyte) / UCHAR_MAX;
+    event_request_timer(tlsmgr_prng_exch_event, dummy, next_period);
+}
+
+/* tlsmgr_reseed_event - re-seed the internal PRNG pool */
+
+static void tlsmgr_reseed_event(int unused_event, void *dummy)
+{
+    int     next_period;
+    unsigned char randbyte;
+    int     must_exit = 0;
+
+    /*
+     * Reseed the internal PRNG from external source. Errors are recoverable.
+     * We simply restart and reconnect without making a fuss. This is OK
+     * because we do require that exchange file updates succeed. The exchange
+     * file is the only entropy source that really matters in the long term.
+     * 
+     * If the administrator specifies an external randomness source that we
+     * could not open upon start-up, restart to see if we can open it now
+     * (and log a nagging warning if we can't).
+     */
+    if (*var_tls_rand_source) {
+
+	/*
+	 * Source is a random device.
+	 */
+	if (rand_source_dev) {
+	    if (tls_prng_dev_read(rand_source_dev, var_tls_rand_bytes) <= 0) {
+		msg_info("cannot read from entropy device %s: %m -- "
+			 "exiting to reopen", DEV_PATH(var_tls_rand_source));
+		must_exit = 1;
+	    }
+	}
+
+	/*
+	 * Source is an EGD compatible socket.
+	 */
+	else if (rand_source_egd) {
+	    if (tls_prng_egd_read(rand_source_egd, var_tls_rand_bytes) <= 0) {
+		msg_info("lost connection to EGD server %s -- "
+		     "exiting to reconnect", EGD_PATH(var_tls_rand_source));
+		must_exit = 1;
+	    }
+	}
+
+	/*
+	 * Source is a regular file. Read the content once and close the
+	 * file.
+	 */
+	else if (rand_source_file) {
+	    if (tls_prng_file_read(rand_source_file, var_tls_rand_bytes) <= 0)
+		msg_warn("cannot read from entropy file %s: %m",
+			 var_tls_rand_source);
+	    tls_prng_file_close(rand_source_file);
+	    rand_source_file = 0;
+	    var_tls_rand_source[0] = 0;
+	}
+
+	/*
+	 * Could not open the external source upon start-up. See if we can
+	 * open it this time. Save PRNG state before we exit.
+	 */
+	else {
+	    msg_info("exiting to reopen external entropy source %s",
+		     var_tls_rand_source);
+	    must_exit = 1;
+	}
+    }
+
+    /*
+     * Save PRNG state in case we must exit.
+     */
+    if (must_exit) {
+	if (rand_exch)
+	    tls_prng_exch_update(rand_exch);
+	sleep(1);
+	exit(0);
+    }
+
+    /*
+     * Make prediction difficult for outsiders and calculate the time for the
+     * next execution randomly.
+     */
+    RAND_bytes(&randbyte, 1);
+    next_period = (var_tls_reseed_period * randbyte) / UCHAR_MAX;
+    event_request_timer(tlsmgr_reseed_event, dummy, next_period);
+}
+
+/* tlsmgr_cache_run_event - start TLS session cache scan */
+
+static void tlsmgr_cache_run_event(int unused_event, void *ctx)
+{
+    const char *myname = "tlsmgr_cache_run_event";
+    TLSMGR_SCACHE *cache = (TLSMGR_SCACHE *) ctx;
+
+    /*
+     * This routine runs when it is time for another TLS session cache scan.
+     * Make sure this routine gets called again in the future.
+     * 
+     * Don't start a new scan when the timer goes off while cache cleanup is
+     * still in progress.
+     */
+    if (cache->cache_info->verbose)
+	msg_info("%s: start TLS %s session cache cleanup",
+		 myname, cache->cache_label);
+
+    if (cache->cache_active == 0)
+	cache->cache_active =
+	    tls_scache_sequence(cache->cache_info, DICT_SEQ_FUN_FIRST,
+				TLS_SCACHE_SEQUENCE_NOTHING);
+
+    event_request_timer(tlsmgr_cache_run_event, (void *) cache,
+			cache->cache_info->timeout);
+}
+
+/* tlsmgr_key - return matching or current RFC 5077 session ticket keys */
+
+static int tlsmgr_key(VSTRING *buffer, int timeout)
+{
+    TLS_TICKET_KEY *key;
+    TLS_TICKET_KEY tmp;
+    unsigned char *name;
+    time_t  now = time((time_t *) 0);
+
+    /* In tlsmgr requests we encode null key names as empty strings. */
+    name = LEN(buffer) ? (unsigned char *) STR(buffer) : 0;
+
+    /*
+     * Each key's encrypt and subsequent decrypt-only timeout is half of the
+     * total session timeout.
+     */
+    timeout /= 2;
+
+    /* Attempt to locate existing key */
+    if ((key = tls_scache_key(name, now, timeout)) == 0) {
+	if (name == 0) {
+	    /* Create new encryption key */
+	    if (RAND_bytes(tmp.name, TLS_TICKET_NAMELEN) <= 0
+		|| RAND_bytes(tmp.bits, TLS_TICKET_KEYLEN) <= 0
+		|| RAND_bytes(tmp.hmac, TLS_TICKET_MACLEN) <= 0)
+		return (TLS_MGR_STAT_ERR);
+	    tmp.tout = now + timeout - 1;
+	    key = tls_scache_key_rotate(&tmp);
+	} else {
+	    /* No matching decryption key found */
+	    return (TLS_MGR_STAT_ERR);
+	}
+    }
+    /* Return value overwrites name buffer */
+    vstring_memcpy(buffer, (char *) key, sizeof(*key));
+    return (TLS_MGR_STAT_OK);
+}
+
+/* tlsmgr_loop - TLS manager main loop */
+
+static int tlsmgr_loop(char *unused_name, char **unused_argv)
+{
+    struct timeval tv;
+    int     active = 0;
+    TLSMGR_SCACHE *ent;
+
+    /*
+     * Update the PRNG pool with the time of day. We do it here after every
+     * event (including internal timer events and external client request
+     * events), instead of doing it in individual event call-back routines.
+     */
+    GETTIMEOFDAY(&tv);
+    RAND_seed(&tv, sizeof(struct timeval));
+
+    /*
+     * This routine runs as part of the event handling loop, after the event
+     * manager has delivered a timer or I/O event, or after it has waited for
+     * a specified amount of time. The result value of tlsmgr_loop()
+     * specifies how long the event manager should wait for the next event.
+     * 
+     * We use this loop to interleave TLS session cache cleanup with other
+     * activity. Interleaved processing is needed when we use a client-server
+     * protocol for entropy and session state exchange with smtp(8) and
+     * smtpd(8) processes.
+     */
+#define DONT_WAIT	0
+#define WAIT_FOR_EVENT	(-1)
+
+    for (ent = cache_table; ent->cache_label; ++ent) {
+	if (ent->cache_info && ent->cache_active)
+	    active |= ent->cache_active =
+		tls_scache_sequence(ent->cache_info, DICT_SEQ_FUN_NEXT,
+				    TLS_SCACHE_SEQUENCE_NOTHING);
+    }
+
+    return (active ? DONT_WAIT : WAIT_FOR_EVENT);
+}
+
+/* tlsmgr_request_receive - receive request */
+
+static int tlsmgr_request_receive(VSTREAM *client_stream, VSTRING *request)
+{
+    int     count;
+
+    /*
+     * Kluge: choose the protocol depending on the request size.
+     */
+    if (read_wait(vstream_fileno(client_stream), var_ipc_timeout) < 0) {
+	msg_warn("timeout while waiting for data from %s",
+		 VSTREAM_PATH(client_stream));
+	return (-1);
+    }
+    if ((count = peekfd(vstream_fileno(client_stream))) < 0) {
+	msg_warn("cannot examine read buffer of %s: %m",
+		 VSTREAM_PATH(client_stream));
+	return (-1);
+    }
+
+    /*
+     * Short request: master trigger. Use the string+null protocol.
+     */
+    if (count <= 2) {
+	if (vstring_get_null(request, client_stream) == VSTREAM_EOF) {
+	    msg_warn("end-of-input while reading request from %s: %m",
+		     VSTREAM_PATH(client_stream));
+	    return (-1);
+	}
+    }
+
+    /*
+     * Long request: real tlsmgr client. Use the attribute list protocol.
+     */
+    else {
+	if (attr_scan(client_stream,
+		      ATTR_FLAG_MORE | ATTR_FLAG_STRICT,
+		      RECV_ATTR_STR(TLS_MGR_ATTR_REQ, request),
+		      ATTR_TYPE_END) != 1) {
+	    return (-1);
+	}
+    }
+    return (0);
+}
+
+/* tlsmgr_service - respond to external request */
+
+static void tlsmgr_service(VSTREAM *client_stream, char *unused_service,
+			           char **argv)
+{
+    static VSTRING *request = 0;
+    static VSTRING *cache_type = 0;
+    static VSTRING *cache_id = 0;
+    static VSTRING *buffer = 0;
+    int     len;
+    static char wakeup[] = {		/* master wakeup request */
+	TRIGGER_REQ_WAKEUP,
+	0,
+    };
+    TLSMGR_SCACHE *ent;
+    int     status = TLS_MGR_STAT_FAIL;
+
+    /*
+     * Sanity check. This service takes no command-line arguments.
+     */
+    if (argv[0])
+	msg_fatal("unexpected command-line argument: %s", argv[0]);
+
+    /*
+     * Initialize. We're select threaded, so we can use static buffers.
+     */
+    if (request == 0) {
+	request = vstring_alloc(10);
+	cache_type = vstring_alloc(10);
+	cache_id = vstring_alloc(10);
+	buffer = vstring_alloc(10);
+    }
+
+    /*
+     * This routine runs whenever a client connects to the socket dedicated
+     * to the tlsmgr service (including wake up events sent by the master).
+     * All connection-management stuff is handled by the common code in
+     * multi_server.c.
+     */
+    if (tlsmgr_request_receive(client_stream, request) == 0) {
+
+	/*
+	 * Load session from cache.
+	 */
+	if (STREQ(STR(request), TLS_MGR_REQ_LOOKUP)) {
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_TYPE, cache_type),
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_ID, cache_id),
+			  ATTR_TYPE_END) == 2) {
+		for (ent = cache_table; ent->cache_label; ++ent)
+		    if (strcmp(ent->cache_label, STR(cache_type)) == 0)
+			break;
+		if (ent->cache_label == 0) {
+		    msg_warn("bogus cache type \"%s\" in \"%s\" request",
+			     STR(cache_type), TLS_MGR_REQ_LOOKUP);
+		    VSTRING_RESET(buffer);
+		} else if (ent->cache_info == 0) {
+
+		    /*
+		     * Cache type valid, but not enabled
+		     */
+		    VSTRING_RESET(buffer);
+		} else {
+		    status = tls_scache_lookup(ent->cache_info,
+					       STR(cache_id), buffer) ?
+			TLS_MGR_STAT_OK : TLS_MGR_STAT_ERR;
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       SEND_ATTR_DATA(TLS_MGR_ATTR_SESSION,
+				      LEN(buffer), STR(buffer)),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * Save session to cache.
+	 */
+	else if (STREQ(STR(request), TLS_MGR_REQ_UPDATE)) {
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_TYPE, cache_type),
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_ID, cache_id),
+			  RECV_ATTR_DATA(TLS_MGR_ATTR_SESSION, buffer),
+			  ATTR_TYPE_END) == 3) {
+		for (ent = cache_table; ent->cache_label; ++ent)
+		    if (strcmp(ent->cache_label, STR(cache_type)) == 0)
+			break;
+		if (ent->cache_label == 0) {
+		    msg_warn("bogus cache type \"%s\" in \"%s\" request",
+			     STR(cache_type), TLS_MGR_REQ_UPDATE);
+		} else if (ent->cache_info != 0) {
+		    status =
+			tls_scache_update(ent->cache_info, STR(cache_id),
+					  STR(buffer), LEN(buffer)) ?
+			TLS_MGR_STAT_OK : TLS_MGR_STAT_ERR;
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * Delete session from cache.
+	 */
+	else if (STREQ(STR(request), TLS_MGR_REQ_DELETE)) {
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_TYPE, cache_type),
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_ID, cache_id),
+			  ATTR_TYPE_END) == 2) {
+		for (ent = cache_table; ent->cache_label; ++ent)
+		    if (strcmp(ent->cache_label, STR(cache_type)) == 0)
+			break;
+		if (ent->cache_label == 0) {
+		    msg_warn("bogus cache type \"%s\" in \"%s\" request",
+			     STR(cache_type), TLS_MGR_REQ_DELETE);
+		} else if (ent->cache_info != 0) {
+		    status = tls_scache_delete(ent->cache_info,
+					       STR(cache_id)) ?
+			TLS_MGR_STAT_OK : TLS_MGR_STAT_ERR;
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * RFC 5077 TLS session ticket keys
+	 */
+	else if (STREQ(STR(request), TLS_MGR_REQ_TKTKEY)) {
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_DATA(TLS_MGR_ATTR_KEYNAME, buffer),
+			  ATTR_TYPE_END) == 1) {
+		if (LEN(buffer) != 0 && LEN(buffer) != TLS_TICKET_NAMELEN) {
+		    msg_warn("invalid session ticket key name length: %ld",
+			     (long) LEN(buffer));
+		    VSTRING_RESET(buffer);
+		} else if (*smtpd_cache.cache_timeout <= 0) {
+		    status = TLS_MGR_STAT_ERR;
+		    VSTRING_RESET(buffer);
+		} else {
+		    status = tlsmgr_key(buffer, *smtpd_cache.cache_timeout);
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       SEND_ATTR_DATA(TLS_MGR_ATTR_KEYBUF,
+				      LEN(buffer), STR(buffer)),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * Entropy request.
+	 */
+	else if (STREQ(STR(request), TLS_MGR_REQ_SEED)) {
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_INT(TLS_MGR_ATTR_SIZE, &len),
+			  ATTR_TYPE_END) == 1) {
+		VSTRING_RESET(buffer);
+		if (len <= 0 || len > 255) {
+		    msg_warn("bogus seed length \"%d\" in \"%s\" request",
+			     len, TLS_MGR_REQ_SEED);
+		} else {
+		    VSTRING_SPACE(buffer, len);
+		    RAND_bytes((unsigned char *) STR(buffer), len);
+		    vstring_set_payload_size(buffer, len);
+		    status = TLS_MGR_STAT_OK;
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       SEND_ATTR_DATA(TLS_MGR_ATTR_SEED,
+				      LEN(buffer), STR(buffer)),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * Caching policy request.
+	 */
+	else if (STREQ(STR(request), TLS_MGR_REQ_POLICY)) {
+	    int     cachable = 0;
+	    int     timeout = 0;
+
+	    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
+			  RECV_ATTR_STR(TLS_MGR_ATTR_CACHE_TYPE, cache_type),
+			  ATTR_TYPE_END) == 1) {
+		for (ent = cache_table; ent->cache_label; ++ent)
+		    if (strcmp(ent->cache_label, STR(cache_type)) == 0)
+			break;
+		if (ent->cache_label == 0) {
+		    msg_warn("bogus cache type \"%s\" in \"%s\" request",
+			     STR(cache_type), TLS_MGR_REQ_POLICY);
+		} else {
+		    cachable = (ent->cache_info != 0) ? 1 : 0;
+		    timeout = *ent->cache_timeout;
+		    status = TLS_MGR_STAT_OK;
+		}
+	    }
+	    attr_print(client_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+		       SEND_ATTR_INT(TLS_MGR_ATTR_CACHABLE, cachable),
+		       SEND_ATTR_INT(TLS_MGR_ATTR_SESSTOUT, timeout),
+		       ATTR_TYPE_END);
+	}
+
+	/*
+	 * Master trigger. Normally, these triggers arrive only after some
+	 * other process requested the tlsmgr's service. The purpose is to
+	 * restart the tlsmgr after it aborted due to a fatal run-time error,
+	 * so that it can continue its housekeeping even while nothing is
+	 * using TLS.
+	 * 
+	 * XXX Which begs the question, if TLS isn't used often, do we need a
+	 * tlsmgr background process? It could terminate when the session
+	 * caches are empty.
+	 */
+	else if (STREQ(STR(request), wakeup)) {
+	    if (msg_verbose)
+		msg_info("received master trigger");
+	    multi_server_disconnect(client_stream);
+	    return;				/* NOT: vstream_fflush */
+	}
+    }
+
+    /*
+     * Protocol error.
+     */
+    else {
+	attr_print(client_stream, ATTR_FLAG_NONE,
+		   SEND_ATTR_INT(MAIL_ATTR_STATUS, TLS_MGR_STAT_FAIL),
+		   ATTR_TYPE_END);
+    }
+    vstream_fflush(client_stream);
+}
+
+/* tlsmgr_pre_init - pre-jail initialization */
+
+static void tlsmgr_pre_init(char *unused_name, char **unused_argv)
+{
+    char   *path;
+    struct timeval tv;
+    TLSMGR_SCACHE *ent;
+    VSTRING *redirect;
+    HTABLE *dup_filter;
+    const char *dup_label;
+
+    /*
+     * If nothing else works then at least this will get us a few bits of
+     * entropy.
+     * 
+     * XXX This is our first call into the OpenSSL library. We should find out
+     * if this can be moved to the post-jail initialization phase, without
+     * breaking compatibility with existing installations.
+     */
+    GETTIMEOFDAY(&tv);
+    tv.tv_sec ^= getpid();
+    RAND_seed(&tv, sizeof(struct timeval));
+
+    /*
+     * Open the external entropy source. We will not be able to open it again
+     * after we are sent to chroot jail, so we keep it open. Errors are not
+     * fatal. The exchange file (see below) is the only entropy source that
+     * really matters in the long run.
+     * 
+     * Security note: we open the entropy source while privileged, but we don't
+     * access the source until after we release privileges. This way, none of
+     * the OpenSSL code gets to execute while we are privileged.
+     */
+    if (*var_tls_rand_source) {
+
+	/*
+	 * Source is a random device.
+	 */
+	if (!strncmp(var_tls_rand_source, DEV_PREF, DEV_PREF_LEN)) {
+	    path = DEV_PATH(var_tls_rand_source);
+	    rand_source_dev = tls_prng_dev_open(path, TLS_MGR_TIMEOUT);
+	    if (rand_source_dev == 0)
+		msg_warn("cannot open entropy device %s: %m", path);
+	}
+
+	/*
+	 * Source is an EGD compatible socket.
+	 */
+	else if (!strncmp(var_tls_rand_source, EGD_PREF, EGD_PREF_LEN)) {
+	    path = EGD_PATH(var_tls_rand_source);
+	    rand_source_egd = tls_prng_egd_open(path, TLS_MGR_TIMEOUT);
+	    if (rand_source_egd == 0)
+		msg_warn("cannot connect to EGD server %s: %m", path);
+	}
+
+	/*
+	 * Source is regular file. We read this only once.
+	 */
+	else {
+	    rand_source_file =
+		tls_prng_file_open(var_tls_rand_source, TLS_MGR_TIMEOUT);
+	}
+    } else {
+	msg_warn("no entropy source specified with parameter %s",
+		 VAR_TLS_RAND_SOURCE);
+	msg_warn("encryption keys etc. may be predictable");
+    }
+
+    /*
+     * Security: don't create root-owned files that contain untrusted data.
+     * And don't create Postfix-owned files in root-owned directories,
+     * either. We want a correct relationship between (file/directory)
+     * ownership and (file/directory) content.
+     */
+    SAVE_AND_SET_EUGID(var_owner_uid, var_owner_gid);
+    redirect = vstring_alloc(100);
+
+    /*
+     * Open the PRNG exchange file before going to jail, but don't use root
+     * privileges. Start the exchange file read/update pseudo thread after
+     * dropping privileges.
+     */
+    if (*var_tls_rand_exch_name) {
+	rand_exch =
+	    tls_prng_exch_open(data_redirect_file(redirect,
+						  var_tls_rand_exch_name));
+	if (rand_exch == 0)
+	    msg_fatal("cannot open PRNG exchange file %s: %m",
+		      var_tls_rand_exch_name);
+    }
+
+    /*
+     * Open the session cache files and discard old information before going
+     * to jail, but don't use root privilege. Start the cache maintenance
+     * pseudo threads after dropping privileges.
+     */
+    dup_filter = htable_create(sizeof(cache_table) / sizeof(cache_table[0]));
+    for (ent = cache_table; ent->cache_label; ++ent) {
+	/* Sanitize session timeout */
+	if (*ent->cache_timeout > 0) {
+	    if (*ent->cache_timeout < TLS_SESSION_LIFEMIN)
+		*ent->cache_timeout = TLS_SESSION_LIFEMIN;
+	} else {
+	    *ent->cache_timeout = 0;
+	}
+	/* External cache database disabled if timeout is non-positive */
+	if (*ent->cache_timeout > 0 && **ent->cache_db) {
+	    if ((dup_label = htable_find(dup_filter, *ent->cache_db)) != 0)
+		msg_fatal("do not use the same TLS cache file %s for %s and %s",
+			  *ent->cache_db, dup_label, ent->cache_label);
+	    htable_enter(dup_filter, *ent->cache_db, ent->cache_label);
+	    ent->cache_info =
+		tls_scache_open(data_redirect_map(redirect, *ent->cache_db),
+				ent->cache_label,
+				tls_log_mask(ent->log_param,
+					   *ent->log_level) & TLS_LOG_CACHE,
+				*ent->cache_timeout);
+	}
+    }
+    htable_free(dup_filter, (void (*) (void *)) 0);
+
+    /*
+     * Clean up and restore privilege.
+     */
+    vstring_free(redirect);
+    RESTORE_SAVED_EUGID();
+}
+
+/* tlsmgr_post_init - post-jail initialization */
+
+static void tlsmgr_post_init(char *unused_name, char **unused_argv)
+{
+    TLSMGR_SCACHE *ent;
+
+#define NULL_EVENT	(0)
+#define NULL_CONTEXT	((char *) 0)
+
+    /*
+     * This routine runs after the skeleton code has entered the chroot jail,
+     * but before any client requests are serviced. Prevent automatic process
+     * suicide after a limited number of client requests or after a limited
+     * amount of idle time.
+     */
+    var_use_limit = 0;
+    var_idle_limit = 0;
+
+    /*
+     * Start the internal PRNG re-seeding pseudo thread first.
+     */
+    if (*var_tls_rand_source) {
+	if (var_tls_reseed_period > INT_MAX / UCHAR_MAX)
+	    var_tls_reseed_period = INT_MAX / UCHAR_MAX;
+	tlsmgr_reseed_event(NULL_EVENT, NULL_CONTEXT);
+    }
+
+    /*
+     * Start the exchange file read/update pseudo thread.
+     */
+    if (*var_tls_rand_exch_name) {
+	if (var_tls_prng_exch_period > INT_MAX / UCHAR_MAX)
+	    var_tls_prng_exch_period = INT_MAX / UCHAR_MAX;
+	tlsmgr_prng_exch_event(NULL_EVENT, NULL_CONTEXT);
+    }
+
+    /*
+     * Start the cache maintenance pseudo threads last. Strictly speaking
+     * there is nothing to clean up after we truncate the database to zero
+     * length, but early cleanup makes verbose logging more informative (we
+     * get positive confirmation that the cleanup threads are running).
+     */
+    for (ent = cache_table; ent->cache_label; ++ent)
+	if (ent->cache_info)
+	    tlsmgr_cache_run_event(NULL_EVENT, (void *) ent);
+}
+
+/* tlsmgr_post_accept - announce our protocol */
+
+static void tlsmgr_post_accept(VSTREAM *stream, char *unused_name,
+			           char **unused_argv, HTABLE *unused_table)
+{
+
+    /*
+     * Announce the protocol.
+     */
+    attr_print(stream, ATTR_FLAG_NONE,
+	       SEND_ATTR_STR(MAIL_ATTR_PROTO, MAIL_ATTR_PROTO_TLSMGR),
+	       ATTR_TYPE_END);
+    (void) vstream_fflush(stream);
+}
+
+
+/* tlsmgr_before_exit - save PRNG state before exit */
+
+static void tlsmgr_before_exit(char *unused_service_name, char **unused_argv)
+{
+
+    /*
+     * Save state before we exit after "postfix reload".
+     */
+    if (rand_exch)
+	tls_prng_exch_update(rand_exch);
+}
+
+MAIL_VERSION_STAMP_DECLARE;
+
+/* main - the main program */
+
+int     main(int argc, char **argv)
+{
+    static const CONFIG_STR_TABLE str_table[] = {
+	VAR_TLS_RAND_SOURCE, DEF_TLS_RAND_SOURCE, &var_tls_rand_source, 0, 0,
+	VAR_TLS_RAND_EXCH_NAME, DEF_TLS_RAND_EXCH_NAME, &var_tls_rand_exch_name, 0, 0,
+	VAR_SMTPD_TLS_SCACHE_DB, DEF_SMTPD_TLS_SCACHE_DB, &var_smtpd_tls_scache_db, 0, 0,
+	VAR_SMTP_TLS_SCACHE_DB, DEF_SMTP_TLS_SCACHE_DB, &var_smtp_tls_scache_db, 0, 0,
+	VAR_LMTP_TLS_SCACHE_DB, DEF_LMTP_TLS_SCACHE_DB, &var_lmtp_tls_scache_db, 0, 0,
+	VAR_SMTPD_TLS_LOGLEVEL, DEF_SMTPD_TLS_LOGLEVEL, &var_smtpd_tls_loglevel, 0, 0,
+	VAR_SMTP_TLS_LOGLEVEL, DEF_SMTP_TLS_LOGLEVEL, &var_smtp_tls_loglevel, 0, 0,
+	VAR_LMTP_TLS_LOGLEVEL, DEF_LMTP_TLS_LOGLEVEL, &var_lmtp_tls_loglevel, 0, 0,
+	0,
+    };
+    static const CONFIG_TIME_TABLE time_table[] = {
+	VAR_TLS_RESEED_PERIOD, DEF_TLS_RESEED_PERIOD, &var_tls_reseed_period, 1, 0,
+	VAR_TLS_PRNG_UPD_PERIOD, DEF_TLS_PRNG_UPD_PERIOD, &var_tls_prng_exch_period, 1, 0,
+	VAR_SMTPD_TLS_SCACHTIME, DEF_SMTPD_TLS_SCACHTIME, &var_smtpd_tls_scache_timeout, 0, MAX_SMTPD_TLS_SCACHETIME,
+	VAR_SMTP_TLS_SCACHTIME, DEF_SMTP_TLS_SCACHTIME, &var_smtp_tls_scache_timeout, 0, MAX_SMTP_TLS_SCACHETIME,
+	VAR_LMTP_TLS_SCACHTIME, DEF_LMTP_TLS_SCACHTIME, &var_lmtp_tls_scache_timeout, 0, MAX_LMTP_TLS_SCACHETIME,
+	0,
+    };
+    static const CONFIG_INT_TABLE int_table[] = {
+	VAR_TLS_RAND_BYTES, DEF_TLS_RAND_BYTES, &var_tls_rand_bytes, 1, 0,
+	0,
+    };
+
+    /*
+     * Fingerprint executables and core dumps.
+     */
+    MAIL_VERSION_STAMP_ALLOCATE;
+
+    /*
+     * Use the multi service skeleton, and require that no-one else is
+     * monitoring our service port while this process runs.
+     */
+    multi_server_main(argc, argv, tlsmgr_service,
+		      CA_MAIL_SERVER_TIME_TABLE(time_table),
+		      CA_MAIL_SERVER_INT_TABLE(int_table),
+		      CA_MAIL_SERVER_STR_TABLE(str_table),
+		      CA_MAIL_SERVER_PRE_INIT(tlsmgr_pre_init),
+		      CA_MAIL_SERVER_POST_INIT(tlsmgr_post_init),
+		      CA_MAIL_SERVER_POST_ACCEPT(tlsmgr_post_accept),
+		      CA_MAIL_SERVER_EXIT(tlsmgr_before_exit),
+		      CA_MAIL_SERVER_LOOP(tlsmgr_loop),
+		      CA_MAIL_SERVER_SOLITARY,
+		      0);
+}
+
+#else
+
+/* tlsmgr_service - respond to external trigger(s), non-TLS version */
+
+static void tlsmgr_service(VSTREAM *unused_stream, char *unused_service,
+			           char **unused_argv)
+{
+    msg_info("TLS support is not compiled in -- exiting");
+}
+
+/* main - the main program, non-TLS version */
+
+int     main(int argc, char **argv)
+{
+
+    /*
+     * 200411 We can't simply use msg_fatal() here, because the logging
+     * hasn't been initialized. The text would disappear because stderr is
+     * redirected to /dev/null.
+     * 
+     * We invoke multi_server_main() to complete program initialization
+     * (including logging) and then invoke the tlsmgr_service() routine to
+     * log the message that says why this program will not run.
+     */
+    multi_server_main(argc, argv, tlsmgr_service,
+		      0);
+}
+
+#endif