src/virtual/virtual.c

/*	$NetBSD: virtual.c,v 1.4 2022/10/08 16:12:51 christos Exp $	*/

/*++
/* NAME
/*	virtual 8
/* SUMMARY
/*	Postfix virtual domain mail delivery agent
/* SYNOPSIS
/*	\fBvirtual\fR [generic Postfix daemon options]
/* DESCRIPTION
/*	The \fBvirtual\fR(8) delivery agent is designed for virtual mail
/*	hosting services. Originally based on the Postfix \fBlocal\fR(8)
/*	delivery
/*	agent, this agent looks up recipients with map lookups of their
/*	full recipient address, instead of using hard-coded unix password
/*	file lookups of the address local part only.
/*
/*	This delivery agent only delivers mail.  Other features such as
/*	mail forwarding, out-of-office notifications, etc., must be
/*	configured via virtual_alias maps or via similar lookup mechanisms.
/* MAILBOX LOCATION
/* .ad
/* .fi
/*	The mailbox location is controlled by the \fBvirtual_mailbox_base\fR
/*	and \fBvirtual_mailbox_maps\fR configuration parameters (see below).
/*	The \fBvirtual_mailbox_maps\fR table is indexed by the recipient
/*	address as described under TABLE SEARCH ORDER below.
/*
/*	The mailbox pathname is constructed as follows:
/*
/* .nf
/*	  \fB$virtual_mailbox_base/$virtual_mailbox_maps(\fIrecipient\fB)\fR
/* .fi
/*
/*	where \fIrecipient\fR is the full recipient address.
/* UNIX MAILBOX FORMAT
/* .ad
/* .fi
/*	When the mailbox location does not end in \fB/\fR, the message
/*	is delivered in UNIX mailbox format.   This format stores multiple
/*	messages in one textfile.
/*
/*	The \fBvirtual\fR(8) delivery agent prepends a "\fBFrom \fIsender
/*	time_stamp\fR" envelope header to each message, prepends a
/*	\fBDelivered-To:\fR message header with the envelope recipient
/*	address,
/*	prepends an \fBX-Original-To:\fR header with the recipient address as
/*	given to Postfix,
/*	prepends a \fBReturn-Path:\fR message header with the
/*	envelope sender address, prepends a \fB>\fR character to lines
/*	beginning with "\fBFrom \fR", and appends an empty line.
/*
/*	The mailbox is locked for exclusive access while delivery is in
/*	progress. In case of problems, an attempt is made to truncate the
/*	mailbox to its original length.
/* QMAIL MAILDIR FORMAT
/* .ad
/* .fi
/*	When the mailbox location ends in \fB/\fR, the message is delivered
/*	in qmail \fBmaildir\fR format. This format stores one message per file.
/*
/*	The \fBvirtual\fR(8) delivery agent prepends a \fBDelivered-To:\fR
/*	message header with the final envelope recipient address,
/*	prepends an \fBX-Original-To:\fR header with the recipient address as
/*	given to Postfix, and prepends a
/*	\fBReturn-Path:\fR message header with the envelope sender address.
/*
/*	By definition, \fBmaildir\fR format does not require application-level
/*	file locking during mail delivery or retrieval.
/* MAILBOX OWNERSHIP
/* .ad
/* .fi
/*	Mailbox ownership is controlled by the \fBvirtual_uid_maps\fR
/*	and \fBvirtual_gid_maps\fR lookup tables, which are indexed
/*	with the full recipient address. Each table provides
/*	a string with the numerical user and group ID, respectively.
/*
/*	The \fBvirtual_minimum_uid\fR parameter imposes a lower bound on
/*	numerical user ID values that may be specified in any
/*	\fBvirtual_uid_maps\fR.
/* CASE FOLDING
/* .ad
/* .fi
/*	All delivery decisions are made using the full recipient
/*	address, folded to lower case. See also the next section
/*	for a few exceptions with optional address extensions.
/* TABLE SEARCH ORDER
/* .ad
/* .fi
/*	Normally, a lookup table is specified as a text file that
/*	serves as input to the \fBpostmap\fR(1) command. The result, an
/*	indexed file in \fBdbm\fR or \fBdb\fR format, is used for fast
/*	searching by the mail system.
/*
/*	The search order is as follows. The search stops
/*	upon the first successful lookup.
/* .IP \(bu
/*	When the recipient has an optional address extension the
/*	\fIuser+extension@domain.tld\fR address is looked up first.
/* .sp
/*	With Postfix versions before 2.1, the optional address extension
/*	is always ignored.
/* .IP \(bu
/*	The \fIuser@domain.tld\fR address, without address extension,
/*	is looked up next.
/* .IP \(bu
/*	Finally, the recipient \fI@domain\fR is looked up.
/* .PP
/*	When the table is provided via other means such as NIS, LDAP
/*	or SQL, the same lookups are done as for ordinary indexed files.
/*
/*	Alternatively, a table can be provided as a regular-expression
/*	map where patterns are given as regular expressions. In that case,
/*	only the full recipient address is given to the regular-expression
/*	map.
/* SECURITY
/* .ad
/* .fi
/*	The \fBvirtual\fR(8) delivery agent is not security sensitive, provided
/*	that the lookup tables with recipient user/group ID information are
/*	adequately protected. This program is not designed to run chrooted.
/*
/*	The \fBvirtual\fR(8) delivery agent disallows regular expression
/*	substitution of $1 etc. in regular expression lookup tables,
/*	because that would open a security hole.
/*
/*	The \fBvirtual\fR(8) delivery agent will silently ignore requests
/*	to use the \fBproxymap\fR(8) server. Instead it will open the
/*	table directly. Before Postfix version 2.2, the virtual
/*	delivery agent will terminate with a fatal error.
/* STANDARDS
/*	RFC 822 (ARPA Internet Text Messages)
/* DIAGNOSTICS
/*	Mail bounces when the recipient has no mailbox or when the
/*	recipient is over disk quota. In all other problem cases, mail for
/*	an existing recipient is deferred and a warning is logged.
/*
/*	Problems and transactions are logged to \fBsyslogd\fR(8)
/*	or \fBpostlogd\fR(8).
/*	Corrupted message files are marked so that the queue
/*	manager can move them to the \fBcorrupt\fR queue afterwards.
/*
/*	Depending on the setting of the \fBnotify_classes\fR parameter,
/*	the postmaster is notified of bounces and of other trouble.
/* BUGS
/*	This delivery agent supports address extensions in email
/*	addresses and in lookup table keys, but does not propagate
/*	address extension information to the result of table lookup.
/*
/*	Postfix should have lookup tables that can return multiple result
/*	attributes. In order to avoid the inconvenience of maintaining
/*	three tables, use an LDAP or MYSQL database.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*	Changes to \fBmain.cf\fR are picked up automatically, as
/*	\fBvirtual\fR(8)
/*	processes run for only a limited amount of time. Use the command
/*	"\fBpostfix reload\fR" to speed up a change.
/*
/*	The text below provides only a parameter summary. See
/*	\fBpostconf\fR(5) for more details including examples.
/* MAILBOX DELIVERY CONTROLS
/* .ad
/* .fi
/* .IP "\fBvirtual_mailbox_base (empty)\fR"
/*	A prefix that the \fBvirtual\fR(8) delivery agent prepends to all pathname
/*	results from $virtual_mailbox_maps table lookups.
/* .IP "\fBvirtual_mailbox_maps (empty)\fR"
/*	Optional lookup tables with all valid addresses in the domains that
/*	match $virtual_mailbox_domains.
/* .IP "\fBvirtual_minimum_uid (100)\fR"
/*	The minimum user ID value that the \fBvirtual\fR(8) delivery agent accepts
/*	as a result from $virtual_uid_maps table lookup.
/* .IP "\fBvirtual_uid_maps (empty)\fR"
/*	Lookup tables with the per-recipient user ID that the \fBvirtual\fR(8)
/*	delivery agent uses while writing to the recipient's mailbox.
/* .IP "\fBvirtual_gid_maps (empty)\fR"
/*	Lookup tables with the per-recipient group ID for \fBvirtual\fR(8) mailbox
/*	delivery.
/* .PP
/*	Available in Postfix version 2.0 and later:
/* .IP "\fBvirtual_mailbox_domains ($virtual_mailbox_maps)\fR"
/*	Postfix is the final destination for the specified list of domains;
/*	mail is delivered via the $virtual_transport mail delivery transport.
/* .IP "\fBvirtual_transport (virtual)\fR"
/*	The default mail delivery transport and next-hop destination for
/*	final delivery to domains listed with $virtual_mailbox_domains.
/* .PP
/*	Available in Postfix version 2.5.3 and later:
/* .IP "\fBstrict_mailbox_ownership (yes)\fR"
/*	Defer delivery when a mailbox file is not owned by its recipient.
/* LOCKING CONTROLS
/* .ad
/* .fi
/* .IP "\fBvirtual_mailbox_lock (see 'postconf -d' output)\fR"
/*	How to lock a UNIX-style \fBvirtual\fR(8) mailbox before attempting
/*	delivery.
/* .IP "\fBdeliver_lock_attempts (20)\fR"
/*	The maximal number of attempts to acquire an exclusive lock on a
/*	mailbox file or \fBbounce\fR(8) logfile.
/* .IP "\fBdeliver_lock_delay (1s)\fR"
/*	The time between attempts to acquire an exclusive lock on a mailbox
/*	file or \fBbounce\fR(8) logfile.
/* .IP "\fBstale_lock_time (500s)\fR"
/*	The time after which a stale exclusive mailbox lockfile is removed.
/* RESOURCE AND RATE CONTROLS
/* .ad
/* .fi
/* .IP "\fBvirtual_mailbox_limit (51200000)\fR"
/*	The maximal size in bytes of an individual \fBvirtual\fR(8) mailbox or
/*	maildir file, or zero (no limit).
/* .PP
/*	Implemented in the qmgr(8) daemon:
/* .IP "\fBvirtual_destination_concurrency_limit ($default_destination_concurrency_limit)\fR"
/*	The maximal number of parallel deliveries to the same destination
/*	via the virtual message delivery transport.
/* .IP "\fBvirtual_destination_recipient_limit ($default_destination_recipient_limit)\fR"
/*	The maximal number of recipients per message for the virtual
/*	message delivery transport.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*	The default location of the Postfix main.cf and master.cf
/*	configuration files.
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*	How much time a Postfix daemon process may take to handle a
/*	request before it is terminated by a built-in watchdog timer.
/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
/*	The maximal number of digits after the decimal point when logging
/*	sub-second delay values.
/* .IP "\fBipc_timeout (3600s)\fR"
/*	The time limit for sending or receiving information over an internal
/*	communication channel.
/* .IP "\fBmax_idle (100s)\fR"
/*	The maximum amount of time that an idle Postfix daemon process waits
/*	for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*	The maximal number of incoming connections that a Postfix daemon
/*	process will service before terminating voluntarily.
/* .IP "\fBprocess_id (read-only)\fR"
/*	The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*	The process name of a Postfix command or daemon process.
/* .IP "\fBqueue_directory (see 'postconf -d' output)\fR"
/*	The location of the Postfix top-level queue directory.
/* .IP "\fBsyslog_facility (mail)\fR"
/*	The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/*	A prefix that is prepended to the process name in syslog
/*	records, so that, for example, "smtpd" becomes "prefix/smtpd".
/* .PP
/*	Available in Postfix version 3.0 and later:
/* .IP "\fBvirtual_delivery_status_filter ($default_delivery_status_filter)\fR"
/*	Optional filter for the \fBvirtual\fR(8) delivery agent to change the
/*	delivery status code or explanatory text of successful or unsuccessful
/*	deliveries.
/* .PP
/*	Available in Postfix version 3.3 and later:
/* .IP "\fBenable_original_recipient (yes)\fR"
/*	Enable support for the original recipient address after an
/*	address is rewritten to a different address (for example with
/*	aliasing or with canonical mapping).
/* .IP "\fBservice_name (read-only)\fR"
/*	The master.cf service name of a Postfix daemon process.
/* .PP
/*	Available in Postfix 3.5 and later:
/* .IP "\fBinfo_log_address_format (external)\fR"
/*	The email address form that will be used in non-debug logging
/*	(info, warning, etc.).
/* SEE ALSO
/*	qmgr(8), queue manager
/*	bounce(8), delivery status reports
/*	postconf(5), configuration parameters
/*	postlogd(8), Postfix logging
/*	syslogd(8), system logging
/* README_FILES
/*	Use "\fBpostconf readme_directory\fR" or
/*	"\fBpostconf html_directory\fR" to locate this information.
/*	VIRTUAL_README, domain hosting howto
/* LICENSE
/* .ad
/* .fi
/*	The Secure Mailer license must be distributed with this software.
/* HISTORY
/* .ad
/* .fi
/*	This delivery agent was originally based on the Postfix local delivery
/*	agent. Modifications mainly consisted of removing code that either
/*	was not applicable or that was not safe in this context: aliases,
/*	~user/.forward files, delivery to "|command" or to /file/name.
/*
/*	The \fBDelivered-To:\fR message header appears in the \fBqmail\fR
/*	system by Daniel Bernstein.
/*
/*	The \fBmaildir\fR structure appears in the \fBqmail\fR system
/*	by Daniel Bernstein.
/* AUTHOR(S)
/*	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
/*
/*	Andrew McNamara
/*	andrewm@connect.com.au
/*	connect.com.au Pty. Ltd.
/*	Level 3, 213 Miller St
/*	North Sydney 2060, NSW, Australia
/*--*/

/* System library. */

#include <sys_defs.h>
#include <stdlib.h>
#ifdef USE_PATHS_H
#include <paths.h>			/* XXX mail_spool_dir dependency */
#endif

/* Utility library. */

#include <msg.h>
#include <vstring.h>
#include <vstream.h>
#include <iostuff.h>
#include <set_eugid.h>
#include <dict.h>

/* Global library. */

#include <mail_queue.h>
#include <recipient_list.h>
#include <deliver_request.h>
#include <deliver_completed.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_conf.h>
#include <mail_params.h>
#include <mail_addr_find.h>
#include <flush_clnt.h>

/* Single server skeleton. */

#include <mail_server.h>

/* Application-specific. */

#include "virtual.h"

 /*
  * Tunable parameters.
  */
char   *var_virt_mailbox_maps;
char   *var_virt_uid_maps;
char   *var_virt_gid_maps;
int     var_virt_minimum_uid;
char   *var_virt_mailbox_base;
char   *var_virt_mailbox_lock;
long    var_virt_mailbox_limit;
char   *var_mail_spool_dir;		/* XXX dependency fix */
bool    var_strict_mbox_owner;
char   *var_virt_dsn_filter;

 /*
  * Mappings.
  */
MAPS   *virtual_mailbox_maps;
MAPS   *virtual_uid_maps;
MAPS   *virtual_gid_maps;

 /*
  * Bit masks.
  */
int     virtual_mbox_lock_mask;

/* local_deliver - deliver message with extreme prejudice */

static int local_deliver(DELIVER_REQUEST *rqst, char *service)
{
    const char *myname = "local_deliver";
    RECIPIENT *rcpt_end = rqst->rcpt_list.info + rqst->rcpt_list.len;
    RECIPIENT *rcpt;
    int     rcpt_stat;
    int     msg_stat;
    LOCAL_STATE state;
    USER_ATTR usr_attr;

    if (msg_verbose)
	msg_info("local_deliver: %s from %s", rqst->queue_id, rqst->sender);

    /*
     * Initialize the delivery attributes that are not recipient specific.
     */
    state.level = 0;
    deliver_attr_init(&state.msg_attr);
    state.msg_attr.queue_name = rqst->queue_name;
    state.msg_attr.queue_id = rqst->queue_id;
    state.msg_attr.fp = rqst->fp;
    state.msg_attr.offset = rqst->data_offset;
    state.msg_attr.sender = rqst->sender;
    state.msg_attr.dsn_envid = rqst->dsn_envid;
    state.msg_attr.dsn_ret = rqst->dsn_ret;
    state.msg_attr.relay = service;
    state.msg_attr.msg_stats = rqst->msg_stats;
    RESET_USER_ATTR(usr_attr, state.level);
    state.request = rqst;

    /*
     * Iterate over each recipient named in the delivery request. When the
     * mail delivery status for a given recipient is definite (i.e. bounced
     * or delivered), update the message queue file and cross off the
     * recipient. Update the per-message delivery status.
     */
    for (msg_stat = 0, rcpt = rqst->rcpt_list.info; rcpt < rcpt_end; rcpt++) {
	state.msg_attr.rcpt = *rcpt;
	rcpt_stat = deliver_recipient(state, usr_attr);
	if (rcpt_stat == 0 && (rqst->flags & DEL_REQ_FLAG_SUCCESS))
	    deliver_completed(state.msg_attr.fp, rcpt->offset);
	msg_stat |= rcpt_stat;
    }

    deliver_attr_free(&state.msg_attr);
    return (msg_stat);
}

/* local_service - perform service for client */

static void local_service(VSTREAM *stream, char *service, char **argv)
{
    DELIVER_REQUEST *request;
    int     status;

    /*
     * Sanity check. This service takes no command-line arguments.
     */
    if (argv[0])
	msg_fatal("unexpected command-line argument: %s", argv[0]);

    /*
     * This routine runs whenever a client connects to the UNIX-domain socket
     * that is dedicated to local mail delivery service. What we see below is
     * a little protocol to (1) tell the client that we are ready, (2) read a
     * delivery request from the client, and (3) report the completion status
     * of that request.
     */
    if ((request = deliver_request_read(stream)) != 0) {
	status = local_deliver(request, service);
	deliver_request_done(stream, request, status);
    }
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if ((table = dict_changed_name()) != 0) {
	msg_info("table %s has changed -- restarting", table);
	exit(0);
    }
}

/* post_init - post-jail initialization */

static void post_init(char *unused_name, char **unused_argv)
{

    /*
     * Drop privileges most of the time.
     */
    set_eugid(var_owner_uid, var_owner_gid);

    /*
     * No case folding needed: the recipient address is case folded.
     */
    virtual_mailbox_maps =
	maps_create(VAR_VIRT_MAILBOX_MAPS, var_virt_mailbox_maps,
		    DICT_FLAG_LOCK | DICT_FLAG_PARANOID
		    | DICT_FLAG_UTF8_REQUEST);

    virtual_uid_maps =
	maps_create(VAR_VIRT_UID_MAPS, var_virt_uid_maps,
		    DICT_FLAG_LOCK | DICT_FLAG_PARANOID
		    | DICT_FLAG_UTF8_REQUEST);

    virtual_gid_maps =
	maps_create(VAR_VIRT_GID_MAPS, var_virt_gid_maps,
		    DICT_FLAG_LOCK | DICT_FLAG_PARANOID
		    | DICT_FLAG_UTF8_REQUEST);

    virtual_mbox_lock_mask = mbox_lock_mask(var_virt_mailbox_lock);
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{

    /*
     * Reset the file size limit from the message size limit to the mailbox
     * size limit.
     *
     * We can't have mailbox size limit smaller than the message size limit,
     * because that prohibits the delivery agent from updating the queue
     * file.
     */
    if (ENFORCING_SIZE_LIMIT(var_virt_mailbox_limit)) {
	if (!ENFORCING_SIZE_LIMIT(var_message_limit))
	    msg_fatal("configuration error: %s is limited but %s is "
		    "unlimited", VAR_VIRT_MAILBOX_LIMIT, VAR_MESSAGE_LIMIT);
	if (var_virt_mailbox_limit < var_message_limit)
	    msg_fatal("configuration error: %s is smaller than %s",
		      VAR_VIRT_MAILBOX_LIMIT, VAR_MESSAGE_LIMIT);
	set_file_limit(var_virt_mailbox_limit);
    }

    /*
     * flush client.
     */
    flush_init();
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the single-threaded skeleton */

int     main(int argc, char **argv)
{
    static const CONFIG_INT_TABLE int_table[] = {
	VAR_VIRT_MINUID, DEF_VIRT_MINUID, &var_virt_minimum_uid, 1, 0,
	0,
    };
    static const CONFIG_LONG_TABLE long_table[] = {
	VAR_VIRT_MAILBOX_LIMIT, DEF_VIRT_MAILBOX_LIMIT, &var_virt_mailbox_limit, 0, 0,
	0,
    };
    static const CONFIG_STR_TABLE str_table[] = {
	VAR_MAIL_SPOOL_DIR, DEF_MAIL_SPOOL_DIR, &var_mail_spool_dir, 0, 0,
	VAR_VIRT_MAILBOX_MAPS, DEF_VIRT_MAILBOX_MAPS, &var_virt_mailbox_maps, 0, 0,
	VAR_VIRT_UID_MAPS, DEF_VIRT_UID_MAPS, &var_virt_uid_maps, 0, 0,
	VAR_VIRT_GID_MAPS, DEF_VIRT_GID_MAPS, &var_virt_gid_maps, 0, 0,
	VAR_VIRT_MAILBOX_BASE, DEF_VIRT_MAILBOX_BASE, &var_virt_mailbox_base, 1, 0,
	VAR_VIRT_MAILBOX_LOCK, DEF_VIRT_MAILBOX_LOCK, &var_virt_mailbox_lock, 1, 0,
	VAR_VIRT_DSN_FILTER, DEF_VIRT_DSN_FILTER, &var_virt_dsn_filter, 0, 0,
	0,
    };
    static const CONFIG_BOOL_TABLE bool_table[] = {
	VAR_STRICT_MBOX_OWNER, DEF_STRICT_MBOX_OWNER, &var_strict_mbox_owner,
	0,
    };

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    single_server_main(argc, argv, local_service,
		       CA_MAIL_SERVER_INT_TABLE(int_table),
		       CA_MAIL_SERVER_LONG_TABLE(long_table),
		       CA_MAIL_SERVER_STR_TABLE(str_table),
		       CA_MAIL_SERVER_BOOL_TABLE(bool_table),
		       CA_MAIL_SERVER_PRE_INIT(pre_init),
		       CA_MAIL_SERVER_POST_INIT(post_init),
		       CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
		       CA_MAIL_SERVER_PRIVILEGED,
		       CA_MAIL_SERVER_BOUNCE_INIT(VAR_VIRT_DSN_FILTER,
						  &var_virt_dsn_filter),
		       0);
}