1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
|
/* $OpenBSD: smtp.c,v 1.71 2010/05/19 20:57:10 gilles Exp $ */
/*
* Copyright (c) 2008 Gilles Chehade <gilles@openbsd.org>
* Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
* Copyright (c) 2009 Jacek Masiulaniec <jacekm@dobremiasto.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/tree.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <errno.h>
#include <event.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "smtpd.h"
void smtp_imsg(struct smtpd *, struct imsgev *, struct imsg *);
__dead void smtp_shutdown(void);
void smtp_sig_handler(int, short, void *);
void smtp_setup_events(struct smtpd *);
void smtp_disable_events(struct smtpd *);
void smtp_pause(struct smtpd *);
int smtp_enqueue(struct smtpd *, uid_t *);
void smtp_accept(int, short, void *);
struct session *smtp_new(struct listener *);
struct session *session_lookup(struct smtpd *, u_int64_t);
void
smtp_imsg(struct smtpd *env, struct imsgev *iev, struct imsg *imsg)
{
struct session skey;
struct submit_status *ss;
struct listener *l;
struct session *s;
struct auth *auth;
struct ssl *ssl;
struct dns *dns;
if (iev->proc == PROC_LKA) {
switch (imsg->hdr.type) {
case IMSG_DNS_PTR:
dns = imsg->data;
s = session_lookup(env, dns->id);
if (s == NULL)
fatalx("smtp: impossible quit");
strlcpy(s->s_hostname,
dns->error ? "<unknown>" : dns->host,
sizeof s->s_hostname);
strlcpy(s->s_msg.session_hostname, s->s_hostname,
sizeof s->s_msg.session_hostname);
session_init(s->s_l, s);
return;
}
}
if (iev->proc == PROC_MFA) {
switch (imsg->hdr.type) {
case IMSG_MFA_RCPT:
case IMSG_MFA_MAIL:
log_debug("smtp: got imsg_mfa_mail/rcpt");
ss = imsg->data;
s = session_lookup(env, ss->id);
if (s == NULL)
return;
session_pickup(s, ss);
return;
}
}
if (iev->proc == PROC_QUEUE) {
ss = imsg->data;
switch (imsg->hdr.type) {
case IMSG_QUEUE_CREATE_MESSAGE:
log_debug("smtp: imsg_queue_create_message returned");
s = session_lookup(env, ss->id);
if (s == NULL)
return;
strlcpy(s->s_msg.message_id, ss->u.msgid,
sizeof s->s_msg.message_id);
session_pickup(s, ss);
return;
case IMSG_QUEUE_MESSAGE_FILE:
log_debug("smtp: imsg_queue_message_file returned");
s = session_lookup(env, ss->id);
if (s == NULL) {
close(imsg->fd);
return;
}
s->datafp = fdopen(imsg->fd, "w");
if (s->datafp == NULL) {
/* queue may have experienced tempfail. */
if (ss->code != 421)
fatalx("smtp: fdopen");
close(imsg->fd);
}
session_pickup(s, ss);
return;
case IMSG_QUEUE_TEMPFAIL:
log_debug("smtp: got imsg_queue_tempfail");
skey.s_id = ss->id;
s = SPLAY_FIND(sessiontree, &env->sc_sessions, &skey);
if (s == NULL)
fatalx("smtp: session is gone");
if (s->s_flags & F_WRITEONLY)
/* session is write-only, must not destroy it. */
s->s_msg.status |= S_MESSAGE_TEMPFAILURE;
else
fatalx("smtp: corrupt session");
return;
case IMSG_QUEUE_COMMIT_ENVELOPES:
log_debug("smtp: got imsg_queue_commit_envelopes");
s = session_lookup(env, ss->id);
if (s == NULL)
return;
session_pickup(s, ss);
return;
case IMSG_QUEUE_COMMIT_MESSAGE:
log_debug("smtp: got imsg_queue_commit_message");
s = session_lookup(env, ss->id);
if (s == NULL)
return;
session_pickup(s, ss);
return;
case IMSG_SMTP_ENQUEUE:
imsg_compose_event(iev, IMSG_SMTP_ENQUEUE, 0, 0,
smtp_enqueue(env, NULL), imsg->data,
sizeof(struct message));
return;
}
}
if (iev->proc == PROC_PARENT) {
switch (imsg->hdr.type) {
case IMSG_CONF_RELOAD:
/*
* Reloading may invalidate various pointers our
* sessions rely upon, we better tell clients we
* want them to retry.
*/
SPLAY_FOREACH(s, sessiontree, &env->sc_sessions) {
s->s_l = NULL;
s->s_msg.status |= S_MESSAGE_TEMPFAILURE;
}
if (env->sc_listeners)
smtp_disable_events(env);
imsg_compose_event(iev, IMSG_PARENT_SEND_CONFIG, 0, 0, -1,
NULL, 0);
return;
case IMSG_CONF_START:
if (env->sc_flags & SMTPD_CONFIGURING)
return;
env->sc_flags |= SMTPD_CONFIGURING;
env->sc_listeners = calloc(1, sizeof *env->sc_listeners);
env->sc_ssl = calloc(1, sizeof *env->sc_ssl);
if (env->sc_listeners == NULL || env->sc_ssl == NULL)
fatal(NULL);
TAILQ_INIT(env->sc_listeners);
return;
case IMSG_CONF_SSL:
if (!(env->sc_flags & SMTPD_CONFIGURING))
return;
ssl = calloc(1, sizeof *ssl);
if (ssl == NULL)
fatal(NULL);
*ssl = *(struct ssl *)imsg->data;
ssl->ssl_cert = strdup((char *)imsg->data +
sizeof *ssl);
if (ssl->ssl_cert == NULL)
fatal(NULL);
ssl->ssl_key = strdup((char *)imsg->data + sizeof *ssl +
ssl->ssl_cert_len);
if (ssl->ssl_key == NULL)
fatal(NULL);
SPLAY_INSERT(ssltree, env->sc_ssl, ssl);
return;
case IMSG_CONF_LISTENER:
if (!(env->sc_flags & SMTPD_CONFIGURING))
return;
l = calloc(1, sizeof *l);
if (l == NULL)
fatal(NULL);
*l = *(struct listener *)imsg->data;
l->fd = imsg->fd;
if (l->fd < 0)
fatalx("smtp: listener pass failed");
if (l->flags & F_SSL) {
struct ssl key;
strlcpy(key.ssl_name, l->ssl_cert_name,
sizeof key.ssl_name);
l->ssl = SPLAY_FIND(ssltree, env->sc_ssl, &key);
if (l->ssl == NULL)
fatalx("smtp: ssltree out of sync");
}
TAILQ_INSERT_TAIL(env->sc_listeners, l, entry);
return;
case IMSG_CONF_END:
if (!(env->sc_flags & SMTPD_CONFIGURING))
return;
smtp_setup_events(env);
env->sc_flags &= ~SMTPD_CONFIGURING;
return;
case IMSG_PARENT_AUTHENTICATE:
auth = imsg->data;
s = session_lookup(env, auth->id);
if (s == NULL)
return;
if (auth->success) {
s->s_flags |= F_AUTHENTICATED;
s->s_msg.flags |= F_MESSAGE_AUTHENTICATED;
} else {
s->s_flags &= ~F_AUTHENTICATED;
s->s_msg.flags &= ~F_MESSAGE_AUTHENTICATED;
}
session_pickup(s, NULL);
return;
case IMSG_CTL_VERBOSE:
log_verbose(*(int *)imsg->data);
return;
}
}
if (iev->proc == PROC_CONTROL) {
switch (imsg->hdr.type) {
case IMSG_SMTP_ENQUEUE:
imsg_compose_event(iev, IMSG_SMTP_ENQUEUE,
imsg->hdr.peerid, 0, smtp_enqueue(env, imsg->data),
NULL, 0);
return;
case IMSG_SMTP_PAUSE:
smtp_pause(env);
return;
case IMSG_SMTP_RESUME:
smtp_resume(env);
return;
}
}
fatalx("smtp_imsg: unexpected imsg");
}
void
smtp_sig_handler(int sig, short event, void *p)
{
switch (sig) {
case SIGINT:
case SIGTERM:
smtp_shutdown();
break;
default:
fatalx("smtp_sig_handler: unexpected signal");
}
}
void
smtp_shutdown(void)
{
log_info("smtp server exiting");
_exit(0);
}
pid_t
smtp(struct smtpd *env)
{
pid_t pid;
struct passwd *pw;
struct event ev_sigint;
struct event ev_sigterm;
struct peer peers[] = {
{ PROC_PARENT, imsg_dispatch },
{ PROC_MFA, imsg_dispatch },
{ PROC_QUEUE, imsg_dispatch },
{ PROC_LKA, imsg_dispatch },
{ PROC_CONTROL, imsg_dispatch }
};
switch (pid = fork()) {
case -1:
fatal("smtp: cannot fork");
case 0:
break;
default:
return (pid);
}
ssl_init();
purge_config(env, PURGE_EVERYTHING);
pw = env->sc_pw;
if (chroot(pw->pw_dir) == -1)
fatal("smtp: chroot");
if (chdir("/") == -1)
fatal("smtp: chdir(\"/\")");
smtpd_process = PROC_SMTP;
setproctitle("%s", env->sc_title[smtpd_process]);
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
fatal("smtp: cannot drop privileges");
imsg_callback = smtp_imsg;
event_init();
signal_set(&ev_sigint, SIGINT, smtp_sig_handler, env);
signal_set(&ev_sigterm, SIGTERM, smtp_sig_handler, env);
signal_add(&ev_sigint, NULL);
signal_add(&ev_sigterm, NULL);
signal(SIGPIPE, SIG_IGN);
signal(SIGHUP, SIG_IGN);
/* Initial limit for use by IMSG_SMTP_ENQUEUE, will be tuned later once
* the listening sockets arrive. */
env->sc_maxconn = availdesc() / 2;
config_pipes(env, peers, nitems(peers));
config_peers(env, peers, nitems(peers));
event_dispatch();
smtp_shutdown();
return (0);
}
void
smtp_setup_events(struct smtpd *env)
{
struct listener *l;
int avail = availdesc();
TAILQ_FOREACH(l, env->sc_listeners, entry) {
log_debug("smtp_setup_events: listen on %s port %d flags 0x%01x"
" cert \"%s\"", ss_to_text(&l->ss), ntohs(l->port),
l->flags, l->ssl_cert_name);
session_socket_blockmode(l->fd, BM_NONBLOCK);
if (listen(l->fd, SMTPD_BACKLOG) == -1)
fatal("listen");
l->env = env;
event_set(&l->ev, l->fd, EV_READ|EV_PERSIST, smtp_accept, l);
event_add(&l->ev, NULL);
ssl_setup(env, l);
avail--;
}
/* guarantee 2 fds to each accepted client */
if ((env->sc_maxconn = avail / 2) < 1)
fatalx("smtp_setup_events: fd starvation");
log_debug("smtp: will accept at most %d clients", env->sc_maxconn);
}
void
smtp_disable_events(struct smtpd *env)
{
struct listener *l;
log_debug("smtp_disable_events: closing listening sockets");
while ((l = TAILQ_FIRST(env->sc_listeners)) != NULL) {
TAILQ_REMOVE(env->sc_listeners, l, entry);
event_del(&l->ev);
close(l->fd);
free(l);
}
free(env->sc_listeners);
env->sc_listeners = NULL;
env->sc_maxconn = 0;
}
void
smtp_pause(struct smtpd *env)
{
struct listener *l;
log_debug("smtp_pause: pausing listening sockets");
env->sc_opts |= SMTPD_SMTP_PAUSED;
TAILQ_FOREACH(l, env->sc_listeners, entry)
event_del(&l->ev);
}
void
smtp_resume(struct smtpd *env)
{
struct listener *l;
log_debug("smtp_resume: resuming listening sockets");
env->sc_opts &= ~SMTPD_SMTP_PAUSED;
TAILQ_FOREACH(l, env->sc_listeners, entry)
event_add(&l->ev, NULL);
}
int
smtp_enqueue(struct smtpd *env, uid_t *euid)
{
static struct listener local, *l;
static struct sockaddr_storage sa;
struct session *s;
int fd[2];
if (l == NULL) {
struct addrinfo hints, *res;
l = &local;
strlcpy(l->tag, "local", sizeof(l->tag));
bzero(&hints, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_flags = AI_NUMERICHOST;
if (getaddrinfo("::1", NULL, &hints, &res))
fatal("getaddrinfo");
memcpy(&sa, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);
}
l->env = env;
/*
* Some enqueue requests buffered in IMSG may still arrive even after
* call to smtp_pause() because enqueue listener is not a real socket
* and thus cannot be paused properly.
*/
if (env->sc_opts & SMTPD_SMTP_PAUSED)
return (-1);
if ((s = smtp_new(l)) == NULL)
return (-1);
if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, fd))
fatal("socketpair");
s->s_fd = fd[0];
s->s_ss = sa;
s->s_msg.flags |= F_MESSAGE_ENQUEUED;
if (euid)
bsnprintf(s->s_hostname, sizeof(s->s_hostname), "%d@localhost",
*euid);
else {
strlcpy(s->s_hostname, "localhost", sizeof(s->s_hostname));
s->s_msg.flags |= F_MESSAGE_BOUNCE;
}
strlcpy(s->s_msg.session_hostname, s->s_hostname,
sizeof(s->s_msg.session_hostname));
session_init(l, s);
return (fd[1]);
}
void
smtp_accept(int fd, short event, void *p)
{
struct listener *l = p;
struct session *s;
socklen_t len;
if ((s = smtp_new(l)) == NULL)
return;
len = sizeof(s->s_ss);
if ((s->s_fd = accept(fd, (struct sockaddr *)&s->s_ss, &len)) == -1) {
if (errno == EINTR || errno == ECONNABORTED)
return;
fatal("smtp_accept");
}
s->s_flags |= F_WRITEONLY;
dns_query_ptr(l->env, &s->s_ss, s->s_id);
}
struct session *
smtp_new(struct listener *l)
{
struct smtpd *env = l->env;
struct session *s;
log_debug("smtp_new: incoming client on listener: %p", l);
if (env->sc_opts & SMTPD_SMTP_PAUSED)
fatalx("smtp_new: unexpected client");
if (env->stats->smtp.sessions_active >= env->sc_maxconn) {
log_warnx("client limit hit, disabling incoming connections");
smtp_pause(env);
return (NULL);
}
if ((s = calloc(1, sizeof(*s))) == NULL)
fatal(NULL);
s->s_id = generate_uid();
s->s_env = env;
s->s_l = l;
strlcpy(s->s_msg.tag, l->tag, sizeof(s->s_msg.tag));
SPLAY_INSERT(sessiontree, &env->sc_sessions, s);
env->stats->smtp.sessions++;
env->stats->smtp.sessions_active++;
return (s);
}
/*
* Helper function for handling IMSG replies.
*/
struct session *
session_lookup(struct smtpd *env, u_int64_t id)
{
struct session key;
struct session *s;
key.s_id = id;
s = SPLAY_FIND(sessiontree, &env->sc_sessions, &key);
if (s == NULL)
fatalx("session_lookup: session is gone");
if (!(s->s_flags & F_WRITEONLY))
fatalx("session_lookup: corrupt session");
s->s_flags &= ~F_WRITEONLY;
if (s->s_flags & F_QUIT) {
session_destroy(s);
s = NULL;
}
return (s);
}
|