1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Connection tracking protocol helper module for SCTP.
4  *
5  * Copyright (c) 2004 Kiran Kumar Immidi <immidi_kiran@yahoo.com>
6  * Copyright (c) 2004-2012 Patrick McHardy <kaber@trash.net>
7  *
8  * SCTP is defined in RFC 2960. References to various sections in this code
9  * are to this RFC.
10  */
11 
12 #include <linux/types.h>
13 #include <linux/timer.h>
14 #include <linux/netfilter.h>
15 #include <linux/in.h>
16 #include <linux/ip.h>
17 #include <linux/sctp.h>
18 #include <linux/string.h>
19 #include <linux/seq_file.h>
20 #include <linux/spinlock.h>
21 #include <linux/interrupt.h>
22 #include <net/sctp/checksum.h>
23 
24 #include <net/netfilter/nf_log.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l4proto.h>
27 #include <net/netfilter/nf_conntrack_ecache.h>
28 #include <net/netfilter/nf_conntrack_timeout.h>
29 
30 static const char *const sctp_conntrack_names[] = {
31 	[SCTP_CONNTRACK_NONE]			= "NONE",
32 	[SCTP_CONNTRACK_CLOSED]			= "CLOSED",
33 	[SCTP_CONNTRACK_COOKIE_WAIT]		= "COOKIE_WAIT",
34 	[SCTP_CONNTRACK_COOKIE_ECHOED]		= "COOKIE_ECHOED",
35 	[SCTP_CONNTRACK_ESTABLISHED]		= "ESTABLISHED",
36 	[SCTP_CONNTRACK_SHUTDOWN_SENT]		= "SHUTDOWN_SENT",
37 	[SCTP_CONNTRACK_SHUTDOWN_RECD]		= "SHUTDOWN_RECD",
38 	[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT]	= "SHUTDOWN_ACK_SENT",
39 	[SCTP_CONNTRACK_HEARTBEAT_SENT]		= "HEARTBEAT_SENT",
40 };
41 
42 #define SECS  * HZ
43 #define MINS  * 60 SECS
44 #define HOURS * 60 MINS
45 #define DAYS  * 24 HOURS
46 
47 static const unsigned int sctp_timeouts[SCTP_CONNTRACK_MAX] = {
48 	[SCTP_CONNTRACK_CLOSED]			= 10 SECS,
49 	[SCTP_CONNTRACK_COOKIE_WAIT]		= 3 SECS,
50 	[SCTP_CONNTRACK_COOKIE_ECHOED]		= 3 SECS,
51 	[SCTP_CONNTRACK_ESTABLISHED]		= 210 SECS,
52 	[SCTP_CONNTRACK_SHUTDOWN_SENT]		= 3 SECS,
53 	[SCTP_CONNTRACK_SHUTDOWN_RECD]		= 3 SECS,
54 	[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT]	= 3 SECS,
55 	[SCTP_CONNTRACK_HEARTBEAT_SENT]		= 30 SECS,
56 };
57 
58 #define	SCTP_FLAG_HEARTBEAT_VTAG_FAILED	1
59 
60 #define sNO SCTP_CONNTRACK_NONE
61 #define	sCL SCTP_CONNTRACK_CLOSED
62 #define	sCW SCTP_CONNTRACK_COOKIE_WAIT
63 #define	sCE SCTP_CONNTRACK_COOKIE_ECHOED
64 #define	sES SCTP_CONNTRACK_ESTABLISHED
65 #define	sSS SCTP_CONNTRACK_SHUTDOWN_SENT
66 #define	sSR SCTP_CONNTRACK_SHUTDOWN_RECD
67 #define	sSA SCTP_CONNTRACK_SHUTDOWN_ACK_SENT
68 #define	sHS SCTP_CONNTRACK_HEARTBEAT_SENT
69 #define	sIV SCTP_CONNTRACK_MAX
70 
71 /*
72 	These are the descriptions of the states:
73 
74 NOTE: These state names are tantalizingly similar to the states of an
75 SCTP endpoint. But the interpretation of the states is a little different,
76 considering that these are the states of the connection and not of an end
77 point. Please note the subtleties. -Kiran
78 
79 NONE              - Nothing so far.
80 COOKIE WAIT       - We have seen an INIT chunk in the original direction, or also
81 		    an INIT_ACK chunk in the reply direction.
82 COOKIE ECHOED     - We have seen a COOKIE_ECHO chunk in the original direction.
83 ESTABLISHED       - We have seen a COOKIE_ACK in the reply direction.
84 SHUTDOWN_SENT     - We have seen a SHUTDOWN chunk in the original direction.
85 SHUTDOWN_RECD     - We have seen a SHUTDOWN chunk in the reply direction.
86 SHUTDOWN_ACK_SENT - We have seen a SHUTDOWN_ACK chunk in the direction opposite
87 		    to that of the SHUTDOWN chunk.
88 CLOSED            - We have seen a SHUTDOWN_COMPLETE chunk in the direction of
89 		    the SHUTDOWN chunk. Connection is closed.
90 HEARTBEAT_SENT    - We have seen a HEARTBEAT in a new flow.
91 */
92 
93 /* TODO
94  - I have assumed that the first INIT is in the original direction.
95  This messes things when an INIT comes in the reply direction in CLOSED
96  state.
97  - Check the error type in the reply dir before transitioning from
98 cookie echoed to closed.
99  - Sec 5.2.4 of RFC 2960
100  - Full Multi Homing support.
101 */
102 
103 /* SCTP conntrack state transitions */
104 static const u8 sctp_conntracks[2][11][SCTP_CONNTRACK_MAX] = {
105 	{
106 /*	ORIGINAL	*/
107 /*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
108 /* init         */ {sCL, sCL, sCW, sCE, sES, sCL, sCL, sSA, sCW},
109 /* init_ack     */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},
110 /* abort        */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
111 /* shutdown     */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL},
112 /* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA, sSA},
113 /* error        */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},/* Can't have Stale cookie*/
114 /* cookie_echo  */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA, sCL},/* 5.2.4 - Big TODO */
115 /* cookie_ack   */ {sCL, sCL, sCW, sES, sES, sSS, sSR, sSA, sCL},/* Can't come in orig dir */
116 /* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL, sCL},
117 /* heartbeat    */ {sHS, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
118 /* heartbeat_ack*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
119 	},
120 	{
121 /*	REPLY	*/
122 /*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
123 /* init         */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV},/* INIT in sCL Big TODO */
124 /* init_ack     */ {sIV, sCW, sCW, sCE, sES, sSS, sSR, sSA, sIV},
125 /* abort        */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV},
126 /* shutdown     */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA, sIV},
127 /* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA, sIV},
128 /* error        */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA, sIV},
129 /* cookie_echo  */ {sIV, sCL, sCE, sCE, sES, sSS, sSR, sSA, sIV},/* Can't come in reply dir */
130 /* cookie_ack   */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA, sIV},
131 /* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL, sIV},
132 /* heartbeat    */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
133 /* heartbeat_ack*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sES},
134 	}
135 };
136 
137 #ifdef CONFIG_NF_CONNTRACK_PROCFS
138 /* Print out the private part of the conntrack. */
sctp_print_conntrack(struct seq_file * s,struct nf_conn * ct)139 static void sctp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
140 {
141 	seq_printf(s, "%s ", sctp_conntrack_names[ct->proto.sctp.state]);
142 }
143 #endif
144 
145 /* do_basic_checks ensures sch->length > 0, do not use before */
146 #define for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count)	\
147 for ((offset) = (dataoff) + sizeof(struct sctphdr), (count) = 0;	\
148 	(offset) < (skb)->len &&					\
149 	((sch) = skb_header_pointer((skb), (offset), sizeof(_sch), &(_sch)));	\
150 	(offset) += (ntohs((sch)->length) + 3) & ~3, (count)++)
151 
152 /* Some validity checks to make sure the chunks are fine */
do_basic_checks(struct nf_conn * ct,const struct sk_buff * skb,unsigned int dataoff,unsigned long * map,const struct nf_hook_state * state)153 static int do_basic_checks(struct nf_conn *ct,
154 			   const struct sk_buff *skb,
155 			   unsigned int dataoff,
156 			   unsigned long *map,
157 			   const struct nf_hook_state *state)
158 {
159 	u_int32_t offset, count;
160 	struct sctp_chunkhdr _sch, *sch;
161 	int flag;
162 
163 	flag = 0;
164 
165 	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
166 		if (sch->type == SCTP_CID_INIT ||
167 		    sch->type == SCTP_CID_INIT_ACK ||
168 		    sch->type == SCTP_CID_SHUTDOWN_COMPLETE)
169 			flag = 1;
170 
171 		/*
172 		 * Cookie Ack/Echo chunks not the first OR
173 		 * Init / Init Ack / Shutdown compl chunks not the only chunks
174 		 * OR zero-length.
175 		 */
176 		if (((sch->type == SCTP_CID_COOKIE_ACK ||
177 		      sch->type == SCTP_CID_COOKIE_ECHO ||
178 		      flag) &&
179 		     count != 0) || !sch->length) {
180 			nf_ct_l4proto_log_invalid(skb, ct, state,
181 						  "%s failed. chunk num %d, type %d, len %d flag %d\n",
182 						  __func__, count, sch->type, sch->length, flag);
183 			return 1;
184 		}
185 
186 		if (map)
187 			set_bit(sch->type, map);
188 	}
189 
190 	return count == 0;
191 }
192 
sctp_new_state(enum ip_conntrack_dir dir,enum sctp_conntrack cur_state,int chunk_type)193 static int sctp_new_state(enum ip_conntrack_dir dir,
194 			  enum sctp_conntrack cur_state,
195 			  int chunk_type)
196 {
197 	int i;
198 
199 	switch (chunk_type) {
200 	case SCTP_CID_INIT:
201 		i = 0;
202 		break;
203 	case SCTP_CID_INIT_ACK:
204 		i = 1;
205 		break;
206 	case SCTP_CID_ABORT:
207 		i = 2;
208 		break;
209 	case SCTP_CID_SHUTDOWN:
210 		i = 3;
211 		break;
212 	case SCTP_CID_SHUTDOWN_ACK:
213 		i = 4;
214 		break;
215 	case SCTP_CID_ERROR:
216 		i = 5;
217 		break;
218 	case SCTP_CID_COOKIE_ECHO:
219 		i = 6;
220 		break;
221 	case SCTP_CID_COOKIE_ACK:
222 		i = 7;
223 		break;
224 	case SCTP_CID_SHUTDOWN_COMPLETE:
225 		i = 8;
226 		break;
227 	case SCTP_CID_HEARTBEAT:
228 		i = 9;
229 		break;
230 	case SCTP_CID_HEARTBEAT_ACK:
231 		i = 10;
232 		break;
233 	default:
234 		/* Other chunks like DATA or SACK do not change the state */
235 		pr_debug("Unknown chunk type %d, Will stay in %s\n",
236 			 chunk_type, sctp_conntrack_names[cur_state]);
237 		return cur_state;
238 	}
239 
240 	return sctp_conntracks[dir][i][cur_state];
241 }
242 
243 /* Don't need lock here: this conntrack not in circulation yet */
244 static noinline bool
sctp_new(struct nf_conn * ct,const struct sk_buff * skb,const struct sctphdr * sh,unsigned int dataoff)245 sctp_new(struct nf_conn *ct, const struct sk_buff *skb,
246 	 const struct sctphdr *sh, unsigned int dataoff)
247 {
248 	enum sctp_conntrack new_state;
249 	const struct sctp_chunkhdr *sch;
250 	struct sctp_chunkhdr _sch;
251 	u32 offset, count;
252 
253 	memset(&ct->proto.sctp, 0, sizeof(ct->proto.sctp));
254 	new_state = SCTP_CONNTRACK_MAX;
255 	for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count) {
256 		new_state = sctp_new_state(IP_CT_DIR_ORIGINAL,
257 					   SCTP_CONNTRACK_NONE, sch->type);
258 
259 		/* Invalid: delete conntrack */
260 		if (new_state == SCTP_CONNTRACK_NONE ||
261 		    new_state == SCTP_CONNTRACK_MAX) {
262 			pr_debug("nf_conntrack_sctp: invalid new deleting.\n");
263 			return false;
264 		}
265 
266 		/* Copy the vtag into the state info */
267 		if (sch->type == SCTP_CID_INIT) {
268 			struct sctp_inithdr _inithdr, *ih;
269 			/* Sec 8.5.1 (A) */
270 			if (sh->vtag)
271 				return false;
272 
273 			ih = skb_header_pointer(skb, offset + sizeof(_sch),
274 						sizeof(_inithdr), &_inithdr);
275 			if (!ih)
276 				return false;
277 
278 			pr_debug("Setting vtag %x for new conn\n",
279 				 ih->init_tag);
280 
281 			ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = ih->init_tag;
282 		} else if (sch->type == SCTP_CID_HEARTBEAT) {
283 			pr_debug("Setting vtag %x for secondary conntrack\n",
284 				 sh->vtag);
285 			ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] = sh->vtag;
286 		} else if (sch->type == SCTP_CID_SHUTDOWN_ACK) {
287 		/* If it is a shutdown ack OOTB packet, we expect a return
288 		   shutdown complete, otherwise an ABORT Sec 8.4 (5) and (8) */
289 			pr_debug("Setting vtag %x for new conn OOTB\n",
290 				 sh->vtag);
291 			ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = sh->vtag;
292 		}
293 
294 		ct->proto.sctp.state = SCTP_CONNTRACK_NONE;
295 	}
296 
297 	return true;
298 }
299 
sctp_error(struct sk_buff * skb,unsigned int dataoff,const struct nf_hook_state * state)300 static bool sctp_error(struct sk_buff *skb,
301 		       unsigned int dataoff,
302 		       const struct nf_hook_state *state)
303 {
304 	const struct sctphdr *sh;
305 	const char *logmsg;
306 
307 	if (skb->len < dataoff + sizeof(struct sctphdr)) {
308 		logmsg = "nf_ct_sctp: short packet ";
309 		goto out_invalid;
310 	}
311 	if (state->hook == NF_INET_PRE_ROUTING &&
312 	    state->net->ct.sysctl_checksum &&
313 	    skb->ip_summed == CHECKSUM_NONE) {
314 		if (skb_ensure_writable(skb, dataoff + sizeof(*sh))) {
315 			logmsg = "nf_ct_sctp: failed to read header ";
316 			goto out_invalid;
317 		}
318 		sh = (const struct sctphdr *)(skb->data + dataoff);
319 		if (sh->checksum != sctp_compute_cksum(skb, dataoff)) {
320 			logmsg = "nf_ct_sctp: bad CRC ";
321 			goto out_invalid;
322 		}
323 		skb->ip_summed = CHECKSUM_UNNECESSARY;
324 	}
325 	return false;
326 out_invalid:
327 	nf_l4proto_log_invalid(skb, state, IPPROTO_SCTP, "%s", logmsg);
328 	return true;
329 }
330 
331 /* Returns verdict for packet, or -NF_ACCEPT for invalid. */
nf_conntrack_sctp_packet(struct nf_conn * ct,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,const struct nf_hook_state * state)332 int nf_conntrack_sctp_packet(struct nf_conn *ct,
333 			     struct sk_buff *skb,
334 			     unsigned int dataoff,
335 			     enum ip_conntrack_info ctinfo,
336 			     const struct nf_hook_state *state)
337 {
338 	enum sctp_conntrack new_state, old_state;
339 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
340 	const struct sctphdr *sh;
341 	struct sctphdr _sctph;
342 	const struct sctp_chunkhdr *sch;
343 	struct sctp_chunkhdr _sch;
344 	u_int32_t offset, count;
345 	unsigned int *timeouts;
346 	unsigned long map[256 / sizeof(unsigned long)] = { 0 };
347 	bool ignore = false;
348 
349 	if (sctp_error(skb, dataoff, state))
350 		return -NF_ACCEPT;
351 
352 	sh = skb_header_pointer(skb, dataoff, sizeof(_sctph), &_sctph);
353 	if (sh == NULL)
354 		goto out;
355 
356 	if (do_basic_checks(ct, skb, dataoff, map, state) != 0)
357 		goto out;
358 
359 	if (!nf_ct_is_confirmed(ct)) {
360 		/* If an OOTB packet has any of these chunks discard (Sec 8.4) */
361 		if (test_bit(SCTP_CID_ABORT, map) ||
362 		    test_bit(SCTP_CID_SHUTDOWN_COMPLETE, map) ||
363 		    test_bit(SCTP_CID_COOKIE_ACK, map))
364 			return -NF_ACCEPT;
365 
366 		if (!sctp_new(ct, skb, sh, dataoff))
367 			return -NF_ACCEPT;
368 	}
369 
370 	/* Check the verification tag (Sec 8.5) */
371 	if (!test_bit(SCTP_CID_INIT, map) &&
372 	    !test_bit(SCTP_CID_SHUTDOWN_COMPLETE, map) &&
373 	    !test_bit(SCTP_CID_COOKIE_ECHO, map) &&
374 	    !test_bit(SCTP_CID_ABORT, map) &&
375 	    !test_bit(SCTP_CID_SHUTDOWN_ACK, map) &&
376 	    !test_bit(SCTP_CID_HEARTBEAT, map) &&
377 	    !test_bit(SCTP_CID_HEARTBEAT_ACK, map) &&
378 	    sh->vtag != ct->proto.sctp.vtag[dir]) {
379 		nf_ct_l4proto_log_invalid(skb, ct, state,
380 					  "verification tag check failed %x vs %x for dir %d",
381 					  sh->vtag, ct->proto.sctp.vtag[dir], dir);
382 		goto out;
383 	}
384 
385 	old_state = new_state = SCTP_CONNTRACK_NONE;
386 	spin_lock_bh(&ct->lock);
387 	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
388 		/* Special cases of Verification tag check (Sec 8.5.1) */
389 		if (sch->type == SCTP_CID_INIT) {
390 			/* (A) vtag MUST be zero */
391 			if (sh->vtag != 0)
392 				goto out_unlock;
393 		} else if (sch->type == SCTP_CID_ABORT) {
394 			/* (B) vtag MUST match own vtag if T flag is unset OR
395 			 * MUST match peer's vtag if T flag is set
396 			 */
397 			if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
398 			     sh->vtag != ct->proto.sctp.vtag[dir]) ||
399 			    ((sch->flags & SCTP_CHUNK_FLAG_T) &&
400 			     sh->vtag != ct->proto.sctp.vtag[!dir]))
401 				goto out_unlock;
402 		} else if (sch->type == SCTP_CID_SHUTDOWN_COMPLETE) {
403 			/* (C) vtag MUST match own vtag if T flag is unset OR
404 			 * MUST match peer's vtag if T flag is set
405 			 */
406 			if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
407 			     sh->vtag != ct->proto.sctp.vtag[dir]) ||
408 			    ((sch->flags & SCTP_CHUNK_FLAG_T) &&
409 			     sh->vtag != ct->proto.sctp.vtag[!dir]))
410 				goto out_unlock;
411 		} else if (sch->type == SCTP_CID_COOKIE_ECHO) {
412 			/* (D) vtag must be same as init_vtag as found in INIT_ACK */
413 			if (sh->vtag != ct->proto.sctp.vtag[dir])
414 				goto out_unlock;
415 		} else if (sch->type == SCTP_CID_COOKIE_ACK) {
416 			ct->proto.sctp.init[dir] = 0;
417 			ct->proto.sctp.init[!dir] = 0;
418 		} else if (sch->type == SCTP_CID_HEARTBEAT) {
419 			if (ct->proto.sctp.vtag[dir] == 0) {
420 				pr_debug("Setting %d vtag %x for dir %d\n", sch->type, sh->vtag, dir);
421 				ct->proto.sctp.vtag[dir] = sh->vtag;
422 			} else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
423 				if (test_bit(SCTP_CID_DATA, map) || ignore)
424 					goto out_unlock;
425 
426 				ct->proto.sctp.flags |= SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
427 				ct->proto.sctp.last_dir = dir;
428 				ignore = true;
429 				continue;
430 			} else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
431 				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
432 			}
433 		} else if (sch->type == SCTP_CID_HEARTBEAT_ACK) {
434 			if (ct->proto.sctp.vtag[dir] == 0) {
435 				pr_debug("Setting vtag %x for dir %d\n",
436 					 sh->vtag, dir);
437 				ct->proto.sctp.vtag[dir] = sh->vtag;
438 			} else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
439 				if (test_bit(SCTP_CID_DATA, map) || ignore)
440 					goto out_unlock;
441 
442 				if ((ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) == 0 ||
443 				    ct->proto.sctp.last_dir == dir)
444 					goto out_unlock;
445 
446 				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
447 				ct->proto.sctp.vtag[dir] = sh->vtag;
448 				ct->proto.sctp.vtag[!dir] = 0;
449 			} else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
450 				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
451 			}
452 		}
453 
454 		old_state = ct->proto.sctp.state;
455 		new_state = sctp_new_state(dir, old_state, sch->type);
456 
457 		/* Invalid */
458 		if (new_state == SCTP_CONNTRACK_MAX) {
459 			nf_ct_l4proto_log_invalid(skb, ct, state,
460 						  "Invalid, old_state %d, dir %d, type %d",
461 						  old_state, dir, sch->type);
462 
463 			goto out_unlock;
464 		}
465 
466 		/* If it is an INIT or an INIT ACK note down the vtag */
467 		if (sch->type == SCTP_CID_INIT) {
468 			struct sctp_inithdr _ih, *ih;
469 
470 			ih = skb_header_pointer(skb, offset + sizeof(_sch), sizeof(*ih), &_ih);
471 			if (!ih)
472 				goto out_unlock;
473 
474 			if (ct->proto.sctp.init[dir] && ct->proto.sctp.init[!dir])
475 				ct->proto.sctp.init[!dir] = 0;
476 			ct->proto.sctp.init[dir] = 1;
477 
478 			pr_debug("Setting vtag %x for dir %d\n", ih->init_tag, !dir);
479 			ct->proto.sctp.vtag[!dir] = ih->init_tag;
480 
481 			/* don't renew timeout on init retransmit so
482 			 * port reuse by client or NAT middlebox cannot
483 			 * keep entry alive indefinitely (incl. nat info).
484 			 */
485 			if (new_state == SCTP_CONNTRACK_CLOSED &&
486 			    old_state == SCTP_CONNTRACK_CLOSED &&
487 			    nf_ct_is_confirmed(ct))
488 				ignore = true;
489 		} else if (sch->type == SCTP_CID_INIT_ACK) {
490 			struct sctp_inithdr _ih, *ih;
491 			__be32 vtag;
492 
493 			ih = skb_header_pointer(skb, offset + sizeof(_sch), sizeof(*ih), &_ih);
494 			if (!ih)
495 				goto out_unlock;
496 
497 			vtag = ct->proto.sctp.vtag[!dir];
498 			if (!ct->proto.sctp.init[!dir] && vtag && vtag != ih->init_tag)
499 				goto out_unlock;
500 			/* collision */
501 			if (ct->proto.sctp.init[dir] && ct->proto.sctp.init[!dir] &&
502 			    vtag != ih->init_tag)
503 				goto out_unlock;
504 
505 			pr_debug("Setting vtag %x for dir %d\n", ih->init_tag, !dir);
506 			ct->proto.sctp.vtag[!dir] = ih->init_tag;
507 		}
508 
509 		ct->proto.sctp.state = new_state;
510 		if (old_state != new_state) {
511 			nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
512 			if (new_state == SCTP_CONNTRACK_ESTABLISHED &&
513 			    !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
514 				nf_conntrack_event_cache(IPCT_ASSURED, ct);
515 		}
516 	}
517 	spin_unlock_bh(&ct->lock);
518 
519 	/* allow but do not refresh timeout */
520 	if (ignore)
521 		return NF_ACCEPT;
522 
523 	timeouts = nf_ct_timeout_lookup(ct);
524 	if (!timeouts)
525 		timeouts = nf_sctp_pernet(nf_ct_net(ct))->timeouts;
526 
527 	nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);
528 
529 	return NF_ACCEPT;
530 
531 out_unlock:
532 	spin_unlock_bh(&ct->lock);
533 out:
534 	return -NF_ACCEPT;
535 }
536 
sctp_can_early_drop(const struct nf_conn * ct)537 static bool sctp_can_early_drop(const struct nf_conn *ct)
538 {
539 	switch (ct->proto.sctp.state) {
540 	case SCTP_CONNTRACK_SHUTDOWN_SENT:
541 	case SCTP_CONNTRACK_SHUTDOWN_RECD:
542 	case SCTP_CONNTRACK_SHUTDOWN_ACK_SENT:
543 		return true;
544 	default:
545 		break;
546 	}
547 
548 	return false;
549 }
550 
551 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
552 
553 #include <linux/netfilter/nfnetlink.h>
554 #include <linux/netfilter/nfnetlink_conntrack.h>
555 
sctp_to_nlattr(struct sk_buff * skb,struct nlattr * nla,struct nf_conn * ct,bool destroy)556 static int sctp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
557 			  struct nf_conn *ct, bool destroy)
558 {
559 	struct nlattr *nest_parms;
560 
561 	spin_lock_bh(&ct->lock);
562 	nest_parms = nla_nest_start(skb, CTA_PROTOINFO_SCTP);
563 	if (!nest_parms)
564 		goto nla_put_failure;
565 
566 	if (nla_put_u8(skb, CTA_PROTOINFO_SCTP_STATE, ct->proto.sctp.state))
567 		goto nla_put_failure;
568 
569 	if (destroy)
570 		goto skip_state;
571 
572 	if (nla_put_be32(skb, CTA_PROTOINFO_SCTP_VTAG_ORIGINAL,
573 			 ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL]) ||
574 	    nla_put_be32(skb, CTA_PROTOINFO_SCTP_VTAG_REPLY,
575 			 ct->proto.sctp.vtag[IP_CT_DIR_REPLY]))
576 		goto nla_put_failure;
577 
578 skip_state:
579 	spin_unlock_bh(&ct->lock);
580 	nla_nest_end(skb, nest_parms);
581 
582 	return 0;
583 
584 nla_put_failure:
585 	spin_unlock_bh(&ct->lock);
586 	return -1;
587 }
588 
589 static const struct nla_policy sctp_nla_policy[CTA_PROTOINFO_SCTP_MAX+1] = {
590 	[CTA_PROTOINFO_SCTP_STATE]	    = { .type = NLA_U8 },
591 	[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL]  = { .type = NLA_U32 },
592 	[CTA_PROTOINFO_SCTP_VTAG_REPLY]     = { .type = NLA_U32 },
593 };
594 
595 #define SCTP_NLATTR_SIZE ( \
596 		NLA_ALIGN(NLA_HDRLEN + 1) + \
597 		NLA_ALIGN(NLA_HDRLEN + 4) + \
598 		NLA_ALIGN(NLA_HDRLEN + 4))
599 
nlattr_to_sctp(struct nlattr * cda[],struct nf_conn * ct)600 static int nlattr_to_sctp(struct nlattr *cda[], struct nf_conn *ct)
601 {
602 	struct nlattr *attr = cda[CTA_PROTOINFO_SCTP];
603 	struct nlattr *tb[CTA_PROTOINFO_SCTP_MAX+1];
604 	int err;
605 
606 	/* updates may not contain the internal protocol info, skip parsing */
607 	if (!attr)
608 		return 0;
609 
610 	err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_SCTP_MAX, attr,
611 					  sctp_nla_policy, NULL);
612 	if (err < 0)
613 		return err;
614 
615 	if (!tb[CTA_PROTOINFO_SCTP_STATE] ||
616 	    !tb[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL] ||
617 	    !tb[CTA_PROTOINFO_SCTP_VTAG_REPLY])
618 		return -EINVAL;
619 
620 	spin_lock_bh(&ct->lock);
621 	ct->proto.sctp.state = nla_get_u8(tb[CTA_PROTOINFO_SCTP_STATE]);
622 	ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] =
623 		nla_get_be32(tb[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL]);
624 	ct->proto.sctp.vtag[IP_CT_DIR_REPLY] =
625 		nla_get_be32(tb[CTA_PROTOINFO_SCTP_VTAG_REPLY]);
626 	spin_unlock_bh(&ct->lock);
627 
628 	return 0;
629 }
630 #endif
631 
632 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
633 
634 #include <linux/netfilter/nfnetlink.h>
635 #include <linux/netfilter/nfnetlink_cttimeout.h>
636 
sctp_timeout_nlattr_to_obj(struct nlattr * tb[],struct net * net,void * data)637 static int sctp_timeout_nlattr_to_obj(struct nlattr *tb[],
638 				      struct net *net, void *data)
639 {
640 	unsigned int *timeouts = data;
641 	struct nf_sctp_net *sn = nf_sctp_pernet(net);
642 	int i;
643 
644 	if (!timeouts)
645 		timeouts = sn->timeouts;
646 
647 	/* set default SCTP timeouts. */
648 	for (i=0; i<SCTP_CONNTRACK_MAX; i++)
649 		timeouts[i] = sn->timeouts[i];
650 
651 	/* there's a 1:1 mapping between attributes and protocol states. */
652 	for (i=CTA_TIMEOUT_SCTP_UNSPEC+1; i<CTA_TIMEOUT_SCTP_MAX+1; i++) {
653 		if (tb[i]) {
654 			timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
655 		}
656 	}
657 
658 	timeouts[CTA_TIMEOUT_SCTP_UNSPEC] = timeouts[CTA_TIMEOUT_SCTP_CLOSED];
659 	return 0;
660 }
661 
662 static int
sctp_timeout_obj_to_nlattr(struct sk_buff * skb,const void * data)663 sctp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
664 {
665         const unsigned int *timeouts = data;
666 	int i;
667 
668 	for (i=CTA_TIMEOUT_SCTP_UNSPEC+1; i<CTA_TIMEOUT_SCTP_MAX+1; i++) {
669 	        if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
670 			goto nla_put_failure;
671 	}
672         return 0;
673 
674 nla_put_failure:
675         return -ENOSPC;
676 }
677 
678 static const struct nla_policy
679 sctp_timeout_nla_policy[CTA_TIMEOUT_SCTP_MAX+1] = {
680 	[CTA_TIMEOUT_SCTP_CLOSED]		= { .type = NLA_U32 },
681 	[CTA_TIMEOUT_SCTP_COOKIE_WAIT]		= { .type = NLA_U32 },
682 	[CTA_TIMEOUT_SCTP_COOKIE_ECHOED]	= { .type = NLA_U32 },
683 	[CTA_TIMEOUT_SCTP_ESTABLISHED]		= { .type = NLA_U32 },
684 	[CTA_TIMEOUT_SCTP_SHUTDOWN_SENT]	= { .type = NLA_U32 },
685 	[CTA_TIMEOUT_SCTP_SHUTDOWN_RECD]	= { .type = NLA_U32 },
686 	[CTA_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT]	= { .type = NLA_U32 },
687 	[CTA_TIMEOUT_SCTP_HEARTBEAT_SENT]	= { .type = NLA_U32 },
688 	[CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED]	= { .type = NLA_U32 },
689 };
690 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
691 
nf_conntrack_sctp_init_net(struct net * net)692 void nf_conntrack_sctp_init_net(struct net *net)
693 {
694 	struct nf_sctp_net *sn = nf_sctp_pernet(net);
695 	int i;
696 
697 	for (i = 0; i < SCTP_CONNTRACK_MAX; i++)
698 		sn->timeouts[i] = sctp_timeouts[i];
699 
700 	/* timeouts[0] is unused, init it so ->timeouts[0] contains
701 	 * 'new' timeout, like udp or icmp.
702 	 */
703 	sn->timeouts[0] = sctp_timeouts[SCTP_CONNTRACK_CLOSED];
704 }
705 
706 const struct nf_conntrack_l4proto nf_conntrack_l4proto_sctp = {
707 	.l4proto 		= IPPROTO_SCTP,
708 #ifdef CONFIG_NF_CONNTRACK_PROCFS
709 	.print_conntrack	= sctp_print_conntrack,
710 #endif
711 	.can_early_drop		= sctp_can_early_drop,
712 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
713 	.nlattr_size		= SCTP_NLATTR_SIZE,
714 	.to_nlattr		= sctp_to_nlattr,
715 	.from_nlattr		= nlattr_to_sctp,
716 	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,
717 	.nlattr_tuple_size	= nf_ct_port_nlattr_tuple_size,
718 	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
719 	.nla_policy		= nf_ct_port_nla_policy,
720 #endif
721 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
722 	.ctnl_timeout		= {
723 		.nlattr_to_obj	= sctp_timeout_nlattr_to_obj,
724 		.obj_to_nlattr	= sctp_timeout_obj_to_nlattr,
725 		.nlattr_max	= CTA_TIMEOUT_SCTP_MAX,
726 		.obj_size	= sizeof(unsigned int) * SCTP_CONNTRACK_MAX,
727 		.nla_policy	= sctp_timeout_nla_policy,
728 	},
729 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
730 };
731