kernel/netgraph7: Replace usage of MALLOC/FREE with kmalloc/kfree here too.
[dragonfly.git] / sys / netgraph7 / ng_tcpmss.c
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1/*-
2 * ng_tcpmss.c
3 *
4 * Copyright (c) 2004, Alexey Popov <lollypop@flexuser.ru>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice unmodified, this list of conditions, and the following
12 * disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * This software includes fragments of the following programs:
30 * tcpmssd Ruslan Ermilov <ru@FreeBSD.org>
31 *
32 * $FreeBSD: src/sys/netgraph/ng_tcpmss.c,v 1.4 2007/01/15 05:01:31 glebius Exp $
5a975a3d 33 * $DragonFly: src/sys/netgraph7/ng_tcpmss.c,v 1.2 2008/06/26 23:05:35 dillon Exp $
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34 */
35
36/*
37 * This node is netgraph tool for workaround of PMTUD problem. It acts
38 * like filter for IP packets. If configured, it reduces MSS of TCP SYN
39 * packets.
40 *
41 * Configuration can be done by sending NGM_TCPMSS_CONFIG message. The
42 * message sets filter for incoming packets on hook 'inHook'. Packet's
43 * TCP MSS field is lowered to 'maxMSS' parameter and resulting packet
44 * is sent to 'outHook'.
45 *
46 * XXX: statistics are updated not atomically, so they may broke on SMP.
47 */
48
49#include <sys/param.h>
50#include <sys/systm.h>
51#include <sys/errno.h>
52#include <sys/kernel.h>
53#include <sys/malloc.h>
54#include <sys/mbuf.h>
55
56#include <netinet/in.h>
57#include <netinet/in_systm.h>
58#include <netinet/ip.h>
59#include <netinet/tcp.h>
60
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61#include "ng_message.h"
62#include "netgraph.h"
63#include "ng_parse.h"
64#include "ng_tcpmss.h"
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65
66/* Per hook info. */
67typedef struct {
68 hook_p outHook;
69 struct ng_tcpmss_hookstat stats;
70} *hpriv_p;
71
72/* Netgraph methods. */
73static ng_constructor_t ng_tcpmss_constructor;
74static ng_rcvmsg_t ng_tcpmss_rcvmsg;
75static ng_newhook_t ng_tcpmss_newhook;
76static ng_rcvdata_t ng_tcpmss_rcvdata;
77static ng_disconnect_t ng_tcpmss_disconnect;
78
79static int correct_mss(struct tcphdr *, int, uint16_t, int);
80
81/* Parse type for struct ng_tcpmss_hookstat. */
82static const struct ng_parse_struct_field ng_tcpmss_hookstat_type_fields[]
83 = NG_TCPMSS_HOOKSTAT_INFO;
84static const struct ng_parse_type ng_tcpmss_hookstat_type = {
85 &ng_parse_struct_type,
86 &ng_tcpmss_hookstat_type_fields
87};
88
89/* Parse type for struct ng_tcpmss_config. */
90static const struct ng_parse_struct_field ng_tcpmss_config_type_fields[]
91 = NG_TCPMSS_CONFIG_INFO;
92static const struct ng_parse_type ng_tcpmss_config_type = {
93 &ng_parse_struct_type,
94 ng_tcpmss_config_type_fields
95};
96
97/* List of commands and how to convert arguments to/from ASCII. */
98static const struct ng_cmdlist ng_tcpmss_cmds[] = {
99 {
100 NGM_TCPMSS_COOKIE,
101 NGM_TCPMSS_GET_STATS,
102 "getstats",
103 &ng_parse_hookbuf_type,
104 &ng_tcpmss_hookstat_type
105 },
106 {
107 NGM_TCPMSS_COOKIE,
108 NGM_TCPMSS_CLR_STATS,
109 "clrstats",
110 &ng_parse_hookbuf_type,
111 NULL
112 },
113 {
114 NGM_TCPMSS_COOKIE,
115 NGM_TCPMSS_GETCLR_STATS,
116 "getclrstats",
117 &ng_parse_hookbuf_type,
118 &ng_tcpmss_hookstat_type
119 },
120 {
121 NGM_TCPMSS_COOKIE,
122 NGM_TCPMSS_CONFIG,
123 "config",
124 &ng_tcpmss_config_type,
125 NULL
126 },
127 { 0 }
128};
129
130/* Netgraph type descriptor. */
131static struct ng_type ng_tcpmss_typestruct = {
132 .version = NG_ABI_VERSION,
133 .name = NG_TCPMSS_NODE_TYPE,
134 .constructor = ng_tcpmss_constructor,
135 .rcvmsg = ng_tcpmss_rcvmsg,
136 .newhook = ng_tcpmss_newhook,
137 .rcvdata = ng_tcpmss_rcvdata,
138 .disconnect = ng_tcpmss_disconnect,
139 .cmdlist = ng_tcpmss_cmds,
140};
141
142NETGRAPH_INIT(tcpmss, &ng_tcpmss_typestruct);
143
144#define ERROUT(x) { error = (x); goto done; }
145
146/*
147 * Node constructor. No special actions required.
148 */
149static int
150ng_tcpmss_constructor(node_p node)
151{
152 return (0);
153}
154
155/*
156 * Add a hook. Any unique name is OK.
157 */
158static int
159ng_tcpmss_newhook(node_p node, hook_p hook, const char *name)
160{
161 hpriv_p priv;
162
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163 priv = kmalloc(sizeof(*priv), M_NETGRAPH,
164 M_WAITOK | M_NULLOK | M_ZERO);
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165 if (priv == NULL)
166 return (ENOMEM);
167
168 NG_HOOK_SET_PRIVATE(hook, priv);
169
170 return (0);
171}
172
173/*
174 * Receive a control message.
175 */
176static int
177ng_tcpmss_rcvmsg
178(node_p node, item_p item, hook_p lasthook)
179{
180 struct ng_mesg *msg, *resp = NULL;
181 int error = 0;
182
183 NGI_GET_MSG(item, msg);
184
185 switch (msg->header.typecookie) {
186 case NGM_TCPMSS_COOKIE:
187 switch (msg->header.cmd) {
188 case NGM_TCPMSS_GET_STATS:
189 case NGM_TCPMSS_CLR_STATS:
190 case NGM_TCPMSS_GETCLR_STATS:
191 {
192 hook_p hook;
193 hpriv_p priv;
194
195 /* Check that message is long enough. */
196 if (msg->header.arglen != NG_HOOKSIZ)
197 ERROUT(EINVAL);
198
199 /* Find this hook. */
200 hook = ng_findhook(node, (char *)msg->data);
201 if (hook == NULL)
202 ERROUT(ENOENT);
203
204 priv = NG_HOOK_PRIVATE(hook);
205
206 /* Create response. */
207 if (msg->header.cmd != NGM_TCPMSS_CLR_STATS) {
208 NG_MKRESPONSE(resp, msg,
5a975a3d 209 sizeof(struct ng_tcpmss_hookstat), M_WAITOK | M_NULLOK);
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210 if (resp == NULL)
211 ERROUT(ENOMEM);
212 bcopy(&priv->stats, resp->data,
213 sizeof(struct ng_tcpmss_hookstat));
214 }
215
216 if (msg->header.cmd != NGM_TCPMSS_GET_STATS)
217 bzero(&priv->stats,
218 sizeof(struct ng_tcpmss_hookstat));
219 break;
220 }
221 case NGM_TCPMSS_CONFIG:
222 {
223 struct ng_tcpmss_config *set;
224 hook_p in, out;
225 hpriv_p priv;
226
227 /* Check that message is long enough. */
228 if (msg->header.arglen !=
229 sizeof(struct ng_tcpmss_config))
230 ERROUT(EINVAL);
231
232 set = (struct ng_tcpmss_config *)msg->data;
233 in = ng_findhook(node, set->inHook);
234 out = ng_findhook(node, set->outHook);
235 if (in == NULL || out == NULL)
236 ERROUT(ENOENT);
237
238 /* Configure MSS hack. */
239 priv = NG_HOOK_PRIVATE(in);
240 priv->outHook = out;
241 priv->stats.maxMSS = set->maxMSS;
242
243 break;
244 }
245 default:
246 error = EINVAL;
247 break;
248 }
249 break;
250 default:
251 error = EINVAL;
252 break;
253 }
254
255done:
256 NG_RESPOND_MSG(error, node, item, resp);
257 NG_FREE_MSG(msg);
258
259 return (error);
260}
261
262/*
263 * Receive data on a hook, and hack MSS.
264 *
265 */
266static int
267ng_tcpmss_rcvdata(hook_p hook, item_p item)
268{
269 hpriv_p priv = NG_HOOK_PRIVATE(hook);
270 struct mbuf *m = NULL;
271 struct ip *ip;
272 struct tcphdr *tcp;
273 int iphlen, tcphlen, pktlen;
274 int pullup_len = 0;
275 int error = 0;
276
277 /* Drop packets if filter is not configured on this hook. */
278 if (priv->outHook == NULL)
279 goto done;
280
281 NGI_GET_M(item, m);
282
283 /* Update stats on incoming hook. */
284 pktlen = m->m_pkthdr.len;
285 priv->stats.Octets += pktlen;
286 priv->stats.Packets++;
287
288 /* Check whether we configured to fix MSS. */
289 if (priv->stats.maxMSS == 0)
290 goto send;
291
292#define M_CHECK(length) do { \
293 pullup_len += length; \
294 if ((m)->m_pkthdr.len < pullup_len) \
295 goto send; \
296 if ((m)->m_len < pullup_len && \
297 (((m) = m_pullup((m), pullup_len)) == NULL)) \
298 ERROUT(ENOBUFS); \
299 } while (0)
300
301 /* Check mbuf packet size and arrange for IP header. */
302 M_CHECK(sizeof(struct ip));
303 ip = mtod(m, struct ip *);
304
305 /* Check IP version. */
306 if (ip->ip_v != IPVERSION)
307 ERROUT(EINVAL);
308
309 /* Check IP header length. */
310 iphlen = ip->ip_hl << 2;
311 if (iphlen < sizeof(struct ip) || iphlen > pktlen )
312 ERROUT(EINVAL);
313
314 /* Check if it is TCP. */
315 if (!(ip->ip_p == IPPROTO_TCP))
316 goto send;
317
318 /* Check mbuf packet size and arrange for IP+TCP header */
319 M_CHECK(iphlen - sizeof(struct ip) + sizeof(struct tcphdr));
320 ip = mtod(m, struct ip *);
321 tcp = (struct tcphdr *)((caddr_t )ip + iphlen);
322
323 /* Check TCP header length. */
324 tcphlen = tcp->th_off << 2;
325 if (tcphlen < sizeof(struct tcphdr) || tcphlen > pktlen - iphlen)
326 ERROUT(EINVAL);
327
328 /* Check SYN packet and has options. */
329 if (!(tcp->th_flags & TH_SYN) || tcphlen == sizeof(struct tcphdr))
330 goto send;
331
332 /* Update SYN stats. */
333 priv->stats.SYNPkts++;
334
335 M_CHECK(tcphlen - sizeof(struct tcphdr));
336 ip = mtod(m, struct ip *);
337 tcp = (struct tcphdr *)((caddr_t )ip + iphlen);
338
339#undef M_CHECK
340
341 /* Fix MSS and update stats. */
342 if (correct_mss(tcp, tcphlen, priv->stats.maxMSS,
343 m->m_pkthdr.csum_flags))
344 priv->stats.FixedPkts++;
345
346send:
347 /* Deliver frame out destination hook. */
348 NG_FWD_NEW_DATA(error, item, priv->outHook, m);
349
350 return (error);
351
352done:
353 NG_FREE_ITEM(item);
354 NG_FREE_M(m);
355
356 return (error);
357}
358
359/*
360 * Hook disconnection.
361 * We must check all hooks, since they may reference this one.
362 */
363static int
364ng_tcpmss_disconnect(hook_p hook)
365{
366 node_p node = NG_HOOK_NODE(hook);
367 hook_p hook2;
368
369 LIST_FOREACH(hook2, &node->nd_hooks, hk_hooks) {
370 hpriv_p priv = NG_HOOK_PRIVATE(hook2);
371
372 if (priv->outHook == hook)
373 priv->outHook = NULL;
374 }
375
fc025606 376 kfree(NG_HOOK_PRIVATE(hook), M_NETGRAPH);
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377
378 if (NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
379 ng_rmnode_self(NG_HOOK_NODE(hook));
380
381 return (0);
382}
383
384/*
385 * Code from tcpmssd.
386 */
387
388/*-
389 * The following macro is used to update an
390 * internet checksum. "acc" is a 32-bit
391 * accumulation of all the changes to the
392 * checksum (adding in old 16-bit words and
393 * subtracting out new words), and "cksum"
394 * is the checksum value to be updated.
395 */
396#define TCPMSS_ADJUST_CHECKSUM(acc, cksum) do { \
397 acc += cksum; \
398 if (acc < 0) { \
399 acc = -acc; \
400 acc = (acc >> 16) + (acc & 0xffff); \
401 acc += acc >> 16; \
402 cksum = (u_short) ~acc; \
403 } else { \
404 acc = (acc >> 16) + (acc & 0xffff); \
405 acc += acc >> 16; \
406 cksum = (u_short) acc; \
407 } \
408} while (0);
409
410static int
411correct_mss(struct tcphdr *tc, int hlen, uint16_t maxmss, int flags)
412{
413 int olen, optlen;
414 u_char *opt;
415 uint16_t *mss;
416 int accumulate;
417 int res = 0;
418
419 for (olen = hlen - sizeof(struct tcphdr), opt = (u_char *)(tc + 1);
420 olen > 0; olen -= optlen, opt += optlen) {
421 if (*opt == TCPOPT_EOL)
422 break;
423 else if (*opt == TCPOPT_NOP)
424 optlen = 1;
425 else {
426 optlen = *(opt + 1);
427 if (optlen <= 0 || optlen > olen)
428 break;
429 if (*opt == TCPOPT_MAXSEG) {
430 if (optlen != TCPOLEN_MAXSEG)
431 continue;
432 mss = (uint16_t *)(opt + 2);
433 if (ntohs(*mss) > maxmss) {
434 accumulate = *mss;
435 *mss = htons(maxmss);
436 accumulate -= *mss;
437 if ((flags & CSUM_TCP) == 0)
438 TCPMSS_ADJUST_CHECKSUM(accumulate, tc->th_sum);
439 res = 1;
440 }
441 }
442 }
443 }
444 return (res);
445}