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[openwrt/svn-archive/packages.git] / net / siit / src / siit.c
1 /*
2 * siit.c: the Stateless IP/ICMP Translator (SIIT) module for Linux.
3 *
4 *
5 */
6
7 #include <linux/version.h>
8 #include <linux/module.h>
9 #include <linux/sched.h>
10 #include <linux/kernel.h> /* printk() */
11 #include <linux/slab.h>
12
13 #include <linux/errno.h> /* error codes */
14 #include <linux/types.h> /* size_t */
15 #include <linux/interrupt.h> /* mark_bh */
16 #include <linux/random.h>
17 #include <linux/in.h>
18 #include <linux/netdevice.h> /* struct device, and other headers */
19 #include <linux/etherdevice.h> /* eth_type_trans */
20 #include <net/ip.h> /* struct iphdr */
21 #include <net/icmp.h> /* struct icmphdr */
22 #include <net/ipv6.h>
23 #include <net/udp.h>
24 #include <linux/skbuff.h>
25 #include <linux/in6.h>
26 #include <linux/init.h>
27 #include <asm/uaccess.h>
28 #include <asm/checksum.h>
29 #include <net/ip6_checksum.h>
30 #include <linux/in6.h>
31 #include "siit.h"
32
33 MODULE_AUTHOR("Dmitriy Moscalev, Grigory Klyuchnikov, Felix Fietkau");
34
35 /*
36 * If tos_ignore_flag != 0, we don't copy TOS and Traffic Class
37 * from origin paket and set it to 0
38 */
39 int tos_ignore_flag = 0;
40
41 #define siit_stats(_dev) (&(_dev)->stats)
42
43 /*
44 * The Utility stuff
45 */
46
47 #ifdef SIIT_DEBUG
48 /* print dump bytes (data point data area sizeof len and message
49 * before dump.
50 */
51 static int siit_print_dump(char *data, int len, char *message)
52 {
53 int i;
54 int j = 0, k = 1;
55
56 len = len > BUFF_SIZE ? BUFF_SIZE : len;
57 printk("%s:\n", message);
58 for (i=0; i < len; i++, k++) {
59 if( i == len-1 || k == 16) {
60 printk("%02x\n", (~(~0 << 8) & *(data+i)));
61 j = 0;
62 k = 0;
63 }
64 else if (j) {
65 printk("%02x ", (~(~0 << 8) & *(data+i)));
66 j--;
67 }
68 else {
69 printk("%02x", (~(~0 << 8) & *(data+i)));
70 j++;
71 }
72 }
73 return 0;
74 }
75 #endif
76
77 /*
78 * Open and close
79 */
80 static int siit_open(struct net_device *dev)
81 {
82 netif_start_queue(dev);
83 return 0;
84 }
85
86
87 static int siit_release(struct net_device *dev)
88 {
89 netif_stop_queue(dev); /* can't transmit any more */
90 return 0;
91 }
92
93 /*
94 * Translation IPv4 to IPv6 stuff
95 *
96 * ip4_ip6 (src, len, dst, include_flag)
97 *
98 * where
99 * src - buffer with original IPv4 packet,
100 * len - size of original packet,
101 * dst - new buffer for IPv6 packet,
102 * include_flag - if = 1, dst point to IPv4 packet that is ICMP error
103 * included IP packet, else = 0
104 */
105
106 static int ip4_ip6(char *src, int len, char *dst, int include_flag)
107 {
108 struct iphdr *ih4 = (struct iphdr *) src; /* point to current IPv4 header struct */
109 struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
110 struct udphdr *udp_hdr; /* point to current IPv4 UDP header struct */
111
112 struct ipv6hdr *ih6 = (struct ipv6hdr *) dst; /* point to current IPv6 header struct */
113 struct frag_hdr *ih6_frag = (struct frag_hdr *)(dst+sizeof(struct ipv6hdr));
114 /* point to current IPv6 fragment header struct */
115 struct icmp6hdr *icmp6_hdr; /* point to current ICMPv6 header */
116
117 int hdr_len = (int)(ih4->ihl * 4); /* IPv4 header length */
118 int icmp_len; /* ICMPv4 packet length */
119 int plen; /* payload length */
120
121 unsigned int csum; /* need to calculate ICMPv6 and UDP checksum */
122 int fl_csum = 0; /* flag to calculate UDP checksum */
123 int icmperr = 1; /* flag to indicate ICMP error message and to need
124 translate ICMP included IP packet */
125 int fr_flag = 0; /* fragment flag, if = 0 - don't add
126 fragment header */
127 __u16 new_tot_len; /* need to calculate IPv6 total length */
128 __u8 new_nexthdr; /* next header code */
129 __u16 icmp_ptr = 0; /* Pointer field in ICMP_PARAMETERPROB */
130
131 #ifdef SIIT_DEBUG /* print IPv4 header dump */
132 siit_print_dump(src, hdr_len, "siit: ip4_ip6() (in) ip4 header dump");
133 #endif
134
135 /* If DF == 1 && MF == 0 && Fragment Offset == 0
136 * or this packet is ICMP included IP packet
137 * we don't need fragment header */
138 if (ntohs(ih4->frag_off) == IP_DF || include_flag ) {
139 /* not fragment and we need not to add Fragment
140 * Header to IPv6 packet. */
141 /* total length = total length from IPv4 packet */
142 new_tot_len = ntohs(ih4->tot_len);
143
144 if (ih4->protocol == IPPROTO_ICMP)
145 new_nexthdr = NEXTHDR_ICMP;
146 else
147 new_nexthdr = ih4->protocol;
148 }
149 else {
150 /* need to add Fragment Header */
151 fr_flag = 1;
152 /* total length = total length from IPv4 packet +
153 length of Fragment Header */
154 new_tot_len = ntohs(ih4->tot_len) + sizeof(struct frag_hdr);
155 /* IPv6 Header NextHeader = NEXTHDR_FRAGMENT */
156 new_nexthdr = NEXTHDR_FRAGMENT;
157 /* Fragment Header NextHeader copy from IPv4 packet */
158 if (ih4->protocol == IPPROTO_ICMP)
159 ih6_frag->nexthdr = NEXTHDR_ICMP;
160 else
161 ih6_frag->nexthdr = ih4->protocol;
162
163 /* copy frag offset from IPv4 packet */
164 ih6_frag->frag_off = htons((ntohs(ih4->frag_off) & IP_OFFSET) << 3);
165 /* copy MF flag from IPv4 packet */
166 ih6_frag->frag_off = htons((ntohs(ih6_frag->frag_off) |
167 ((ntohs(ih4->frag_off) & IP_MF) >> 13)));
168 /* copy Identification field from IPv4 packet */
169 ih6_frag->identification = htonl(ntohs(ih4->id));
170 /* reserved field initialized to zero */
171 ih6_frag->reserved = 0;
172 }
173
174 /* Form rest IPv6 fields */
175
176 /*
177 * At this point we need to add checking of unxpired source
178 * route optin and if it is, send ICMPv4 "destination
179 * unreacheble/source route failes" Type 3/Code 5 and
180 * drop packet. (NOT RELEASED YET)
181 */
182
183 /* IP version = 6 */
184 ih6->version = 6;
185
186 if (tos_ignore_flag) {
187 ih6->priority = 0;
188 ih6->flow_lbl[0] = 0;
189 } else {
190 ih6->priority = (ih4->tos & 0xf0) >> 4;
191 ih6->flow_lbl[0] = (ih4->tos & 0x0f) << 4;
192 }
193 ih6->flow_lbl[1] = 0;
194 ih6->flow_lbl[2] = 0;
195
196 /* Hop Limit = IPv4 TTL */
197 ih6->hop_limit = ih4->ttl;
198
199 /* Translate source destination addresses,
200 for IPv6 host it's IPv4-translated IPv6 address,
201 for IPv4 host it's IPv4-mapped IPv6 address
202
203 !!WARNING!! Instead IPv4-mapped IPv6 addresses we use addreesses
204 with unused prefix ::ffff:ffff:0:0/96, because KAME implementation
205 doesn't support IPv4-mapped addresses in IPv6 packets and discard them.
206
207 */
208
209 if (include_flag) {
210 /*
211 It's ICMP included IP packet and there is a diffirence
212 in src/dst addresses then src/dst in normal direction
213 */
214
215 /*
216 Source address
217 is IPv4-translated IPv6 address because packet traveled
218 from IPv6 to IPv4 area
219 */
220 ih6->saddr.in6_u.u6_addr32[0] = 0;
221 ih6->saddr.in6_u.u6_addr32[1] = 0;
222 ih6->saddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
223 ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
224
225 /*
226 Destination address
227 is IPv4-mapped address (but it's not IPv4- mapped, we use
228 prefix ::ffff:ffff:0:0/96
229 */
230 ih6->daddr.in6_u.u6_addr32[0] = 0;
231 ih6->daddr.in6_u.u6_addr32[1] = 0;
232 ih6->daddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
233 ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
234 }
235 else {
236
237 /*
238 This is normal case (packet isn't included IP packet)
239
240 Source address
241 is IPv4-mapped address (but it's not IPv4- mapped, we use
242 prefix ::ffff:ffff:0:0/96)
243 */
244 ih6->saddr.in6_u.u6_addr32[0] = 0;
245 ih6->saddr.in6_u.u6_addr32[1] = 0;
246 ih6->saddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
247 ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
248
249 /* Destination address
250 is is IPv4-translated IPv6 address
251 */
252 ih6->daddr.in6_u.u6_addr32[0] = 0;
253 ih6->daddr.in6_u.u6_addr32[1] = 0;
254 ih6->daddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
255 ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
256 }
257
258 /* Payload Length */
259 plen = new_tot_len - hdr_len; /* Payload length = IPv4 total len - IPv4 header len */
260 ih6->payload_len = htons(plen);
261
262 /* Next Header */
263 ih6->nexthdr = new_nexthdr; /* Next Header */
264
265 /* Process ICMP protocols data */
266
267 switch (ih4->protocol) {
268 case IPPROTO_ICMP:
269 if ( (ntohs(ih4->frag_off) & IP_OFFSET) != 0 || (ntohs(ih4->frag_off) & IP_MF) != 0 ) {
270 PDEBUG("ip4_ip6(): don't translate ICMPv4 fragments - packet dropped.\n");
271 return -1;
272 }
273
274 icmp_hdr = (struct icmphdr *) (src+hdr_len); /* point to ICMPv4 header */
275 csum = 0;
276 icmp_len = ntohs(ih4->tot_len) - hdr_len; /* ICMPv4 packet length */
277 icmp6_hdr = (struct icmp6hdr *)(dst+sizeof(struct ipv6hdr)
278 +fr_flag*sizeof(struct frag_hdr)); /* point to ICMPv6 header */
279
280 if (include_flag) {
281 /* ICMPv4 packet cannot be included in ICMPv4 Error message */
282 /* !!! May be it's WRONG !!! ICMPv4 QUERY packet can be included
283 in ICMPv4 Error message */
284 PDEBUG("ip4_ip6(): It's included ICMPv4 in ICMPv4 Error message - packet dropped.\n");
285 return -1;
286 }
287
288 /* Check ICMPv4 Type field */
289 switch (icmp_hdr->type) {
290 /* ICMP Error messages */
291 /* Destination Unreachable (Type 3) */
292 case ICMP_DEST_UNREACH:
293 icmp6_hdr->icmp6_type = ICMPV6_DEST_UNREACH; /* to Type 1 */
294 icmp6_hdr->icmp6_unused = 0;
295 switch (icmp_hdr->code)
296 {
297 case ICMP_NET_UNREACH: /* Code 0 */
298 case ICMP_HOST_UNREACH: /* Code 1 */
299 case ICMP_SR_FAILED: /* Code 5 */
300 case ICMP_NET_UNKNOWN: /* Code 6 */
301 case ICMP_HOST_UNKNOWN: /* Code 7 */
302 case ICMP_HOST_ISOLATED: /* Code 8 */
303 case ICMP_NET_UNR_TOS: /* Code 11 */
304 case ICMP_HOST_UNR_TOS: /* Code 12 */
305 icmp6_hdr->icmp6_code = ICMPV6_NOROUTE; /* to Code 0 */
306 break;
307 case ICMP_PROT_UNREACH: /* Code 2 */
308 icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB; /* to Type 4 */
309 icmp6_hdr->icmp6_code = ICMPV6_UNK_NEXTHDR; /* to Code 1 */
310 /* Set pointer filed to 6, it's octet offset IPv6 Next Header field */
311 icmp6_hdr->icmp6_pointer = htonl(6);
312 break;
313 case ICMP_PORT_UNREACH: /* Code 3 */
314 icmp6_hdr->icmp6_code = ICMPV6_PORT_UNREACH; /* to Code 4 */
315 break;
316 case ICMP_FRAG_NEEDED: /* Code 4 */
317 icmp6_hdr->icmp6_type = ICMPV6_PKT_TOOBIG; /* to Type 2 */
318 icmp6_hdr->icmp6_code = 0;
319 /* Correct MTU */
320 if (icmp_hdr->un.frag.mtu == 0)
321 /* we use minimum MTU for IPv4 PMTUv4 RFC1191, section 5;
322 IPv6 implementation wouldn't accept Path MTU < 1280,
323 but it records info correctly to always include
324 a fragment header */
325 icmp6_hdr->icmp6_mtu = htonl(576);
326 else
327 /* needs to adjusted for difference between IPv4/IPv6 headers
328 * SIIT RFC2765, section 3.3,
329 * we assume that difference is 20 bytes */
330 icmp6_hdr->icmp6_mtu = htonl(ntohs(icmp_hdr->un.frag.mtu)+IP4_IP6_HDR_DIFF);
331
332 break;
333 case ICMP_NET_ANO: /* Code 9 */
334 case ICMP_HOST_ANO: /* Code 10 */
335 icmp6_hdr->icmp6_code = ICMPV6_ADM_PROHIBITED; /* to Code 1 */
336 break;
337 default: /* discard any other Code */
338 PDEBUG("ip4_ip6(): Unknown ICMPv4 Type %d Code %d - packet dropped.\n",
339 ICMP_DEST_UNREACH, icmp_hdr->code);
340 return -1;
341 }
342 break;
343 /* Time Exceeded (Type 11) */
344 case ICMP_TIME_EXCEEDED:
345 icmp6_hdr->icmp6_type = ICMPV6_TIME_EXCEED;
346 icmp6_hdr->icmp6_code = icmp_hdr->code;
347 break;
348 /* Parameter Problem (Type 12) */
349 case ICMP_PARAMETERPROB:
350 icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB;
351 icmp6_hdr->icmp6_code = icmp_hdr->code;
352
353 icmp_ptr = ntohs(icmp_hdr->un.echo.id) >> 8;
354 switch (icmp_ptr) {
355 case 0:
356 icmp6_hdr->icmp6_pointer = 0; /* IPv4 Version -> IPv6 Version */
357 break;
358 case 2:
359 icmp6_hdr->icmp6_pointer = __constant_htonl(4); /* IPv4 length -> IPv6 Payload Length */
360 break;
361 case 8:
362 icmp6_hdr->icmp6_pointer = __constant_htonl(7); /* IPv4 TTL -> IPv6 Hop Limit */
363 break;
364 case 9:
365 icmp6_hdr->icmp6_pointer = __constant_htonl(6); /* IPv4 Protocol -> IPv6 Next Header */
366 break;
367 case 12:
368 icmp6_hdr->icmp6_pointer = __constant_htonl(8); /* IPv4 Src Addr -> IPv6 Src Addr */
369 break;
370 case 16:
371 icmp6_hdr->icmp6_pointer = __constant_htonl(24); /* IPv4 Dst Addr -> IPv6 Dst Addr */
372 break;
373 default:
374 icmp6_hdr->icmp6_pointer = 0xffffffff; /* set to all ones in any other cases */
375 break;
376 }
377 break;
378 case ICMP_ECHO:
379 icmperr = 0;
380 icmp6_hdr->icmp6_type = ICMPV6_ECHO_REQUEST;
381 icmp6_hdr->icmp6_code = 0;
382 /* Copy rest ICMP data to new IPv6 packet without changing */
383 memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
384 break;
385
386 case ICMP_ECHOREPLY:
387 icmperr = 0;
388 icmp6_hdr->icmp6_type = ICMPV6_ECHO_REPLY;
389 icmp6_hdr->icmp6_code = 0;
390 /* Copy rest ICMP data to new IPv6 packet without changing */
391 memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
392 break;
393
394 /* Discard any other ICMP messages */
395 default:
396 PDEBUG("ip4_ip6(): Unknown ICMPv4 packet Type %x - packet dropped.\n", icmp_hdr->type);
397 return -1;
398 }
399
400 /* Now if it's ICMPv4 Error message we must translate included IP packet */
401
402 if (icmperr) {
403 /* Call our ip4_ip6() to translate included IP packet */
404 if (ip4_ip6(src+hdr_len+sizeof(struct icmphdr), len - hdr_len - sizeof(struct icmphdr),
405 dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr)
406 +sizeof(struct icmp6hdr), 1) == -1) {
407 PDEBUG("ip4_ip6(): Uncorrect translation of ICMPv4 Error message - packet dropped.\n");
408 return -1;
409 }
410 /* correct ICMPv6 packet length for diffirence between IPv4 and IPv6 headers
411 in included IP packet
412 */
413 icmp_len += 20;
414 /* and correct Payload length for diffirence between IPv4 and IPv6 headers */
415 plen += 20;
416 ih6->payload_len = htons(plen);
417 }
418
419 /* Calculate ICMPv6 checksum */
420
421 icmp6_hdr->icmp6_cksum = 0;
422 csum = 0;
423
424 csum = csum_partial((u_char *)icmp6_hdr, icmp_len, csum);
425 icmp6_hdr->icmp6_cksum = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, icmp_len,
426 IPPROTO_ICMPV6, csum);
427 break;
428
429 /* Process TCP protocols data */
430 case IPPROTO_TCP:
431 /* Copy TCP data to new IPv6 packet without changing */
432 memcpy(dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr),
433 src+hdr_len, len - hdr_len);
434 break;
435
436 /* Process UDP protocols data */
437 case IPPROTO_UDP:
438 udp_hdr = (struct udphdr *)(src+hdr_len);
439 if ((ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
440 if ((ntohs(ih4->frag_off) & IP_MF) != 0) {
441 /* It's a first fragment */
442 if (udp_hdr->check == 0) {
443 /* System management event */
444 printk("siit: First fragment of UDP with zero checksum - packet droped\n");
445 printk("siit: addr: %x src port: %d dst port: %d\n",
446 htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
447 return -1;
448 }
449 }
450 else if (udp_hdr->check == 0)
451 fl_csum = 1;
452 }
453
454 /* Copy UDP data to new IPv6 packet */
455 udp_hdr = (struct udphdr *)(dst+sizeof(struct ipv6hdr)
456 + fr_flag*sizeof(struct frag_hdr));
457 memcpy((char *)udp_hdr, src+hdr_len, len - hdr_len);
458
459 /* Calculate UDP checksum if UDP checksum in IPv4 packet was ZERO
460 and if it isn't included IP packet
461 */
462 if (fl_csum && (!include_flag)) {
463 udp_hdr->check = 0;
464 csum = 0;
465 csum = csum_partial((unsigned char *)udp_hdr, plen - fr_flag*sizeof(struct frag_hdr), csum);
466 udp_hdr->check = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, plen -
467 fr_flag*sizeof(struct frag_hdr), IPPROTO_UDP, csum);
468 }
469 break;
470
471 /* Discard packets with any other protocol */
472 default:
473 PDEBUG("ip4_ip6(): Unknown upper protocol - packet dropped.\n");
474 return -1;
475 }
476
477 #ifdef SIIT_DEBUG
478 siit_print_dump(dst, sizeof(struct ipv6hdr), "siit: ip4_ip6(): (out) ipv6 header dump");
479 #endif
480
481 return 0;
482 }
483
484 /*
485 * Translation IPv6 to IPv4 stuff
486 *
487 * ip6_ip4(src, len, dst, include_flag)
488 *
489 * where
490 * src - buffer with original IPv6 packet,
491 * len - size of original packet,
492 * dst - new buffer for IPv4 packet,
493 * include_flag - if = 1, dst point to IPv6 packet that is ICMP error
494 * included IP packet, else = 0
495 *
496 */
497
498 static int ip6_ip4(char *src, int len, char *dst, int include_flag)
499 {
500 struct ipv6hdr *ip6_hdr; /* point to current IPv6 header struct */
501 struct iphdr *ip_hdr; /* point to current IPv4 header struct */
502 int opts_len = 0; /* to sum Option Headers length */
503 int icmperr = 1; /* if = 1, indicate that packet is ICMP Error message, else = 0 */
504 int ntot_len = 0; /* to calculate IPv6 Total Length field */
505 int real_len;
506 int len_delta;
507 int ip6_payload_len;
508 int inc_opts_len = 0; /* to sum Option Headers length in ICMP included IP packet */
509 __u8 next_hdr; /* Next Header */
510
511 #ifdef SIIT_DEBUG
512 siit_print_dump(src, sizeof(struct ipv6hdr), "siit: ip6_ip4(): (in) ipv6 header dump");
513 #endif
514
515 if ( (len_delta = len - sizeof(struct ipv6hdr)) >= 0)
516 {
517 ip6_hdr = (struct ipv6hdr *)src;
518 ip_hdr = (struct iphdr *)dst;
519
520 real_len = sizeof(struct iphdr);
521
522 /* Check validation of Saddr & Daddr? is a packet to fall under our translation? */
523 if (include_flag) { /* It's ICMP included IP packet,
524 about process include_flag see comment in ip4_ip6() */
525 if (ip6_hdr->saddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
526 PDEBUG("ip6_ip4(): Included IP packet Src addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
527 ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
528 ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
529 return -1;
530 }
531 if ( ip6_hdr->daddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
532 PDEBUG("ip6_ip4(): Included IP packet Dst addr isn't translated addr: %x%x%x%x, packet dropped.\n",
533 ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
534 ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
535 return -1;
536 }
537 }
538 else { /* It's normal IP packet (not included in ICMP) */
539 if (ip6_hdr->saddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
540 PDEBUG("ip6_ip4(): Src addr isn't translated addr: %x%x%x%x, packet dropped.\n",
541 ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
542 ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
543 return -1;
544 }
545 if ( ip6_hdr->daddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
546 PDEBUG("ip6_ip4(): Dst addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
547 ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
548 ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
549 return -1;
550 }
551 }
552
553 /* Set IPv4 Fragment Offset and ID to 0
554 before process any Option Headers */
555 ip_hdr->frag_off = 0;
556 ip_hdr->id = 0;
557
558 /*
559 * We process only Fragment Header. Any other options headers
560 * are ignored, i.e. there is no attempt to translate them.
561 * However, the Total Length field and the Protocol field would
562 * have to be adjusted to "skip" these extension headers.
563 */
564
565 next_hdr = ip6_hdr->nexthdr;
566
567 /* Hop_by_Hop options header (ip6_hdr->nexthdr = 0). It must
568 * appear only in IPv6 header's Next Header field.
569 */
570 if (next_hdr == NEXTHDR_HOP) {
571 if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
572 {
573 struct ipv6_opt_hdr *ip6h =
574 (struct ipv6_opt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
575 if ( (len_delta -= ip6h->hdrlen*8 + 8) >= 0)
576 {
577 opts_len += ip6h->hdrlen*8 + 8; /* See RFC 2460 page 11:
578 Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by-
579 Hop Options header in 8-octet units, not
580 including the first 8 octets.
581 */
582 next_hdr = ip6h->nexthdr;
583 }
584 else
585 {
586 PDEBUG("ip6_ip4(): hop_by_hop header error, packet droped");
587 /* Generate ICMP Parameter Problem */
588 return -1;
589 }
590 }
591 }
592
593 if (len_delta > 0)
594 {
595 while(next_hdr != NEXTHDR_ICMP && next_hdr != NEXTHDR_TCP
596 && next_hdr != NEXTHDR_UDP)
597 {
598 /* Destination options header */
599 if (next_hdr == NEXTHDR_DEST)
600 {
601 if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
602 {
603 struct ipv6_opt_hdr *ip6d =
604 (struct ipv6_opt_hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
605 if ( (len_delta -= ip6d->hdrlen*8 + 8) >= 0)
606 {
607 opts_len += ip6d->hdrlen*8 + 8;
608 next_hdr = ip6d->nexthdr;
609 }
610 }
611 else
612 {
613 PDEBUG("ip6_ip4(): destination header error, packet droped");
614 /* Generate ICMP Parameter Problem */
615 return -1;
616 }
617 }
618 /* Routing options header */
619 else if (next_hdr == NEXTHDR_ROUTING)
620 {
621 if ( (len_delta - sizeof(struct ipv6_rt_hdr)) >= 0)
622 {
623 struct ipv6_rt_hdr *ip6rt =
624 (struct ipv6_rt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
625 /* RFC 2765 SIIT, 4.1:
626 If a routing header with a non-zero Segments Left field is present
627 then the packet MUST NOT be translated, and an ICMPv6 "parameter
628 problem/ erroneous header field encountered" (Type 4/Code 0) error
629 message, with the Pointer field indicating the first byte of the
630 Segments Left field, SHOULD be returned to the sender.
631 */
632 if (ip6rt->segments_left != 0) {
633 /* Build ICMPv6 "Parameter Problem/Erroneous Header
634 Field Encountered" & drop the packet */
635 /* !!! We don't send ICMPv6 "Parameter Problem" !!! */
636 PDEBUG("ip6_ip4(): routing header type != 0\n");
637 return -1;
638 }
639 if ( (len_delta -= ip6rt->hdrlen*8 + 8) >= 0)
640 {
641 opts_len += ip6rt->hdrlen*8 + 8;
642 next_hdr = ip6rt->nexthdr;
643 }
644 else
645 {
646 PDEBUG("ip6_ip4(): routing header error, packet droped");
647 /* Generate ICMP Parameter Problem */
648 return -1;
649 }
650 }
651 }
652 /* Fragment options header */
653 else if (next_hdr == NEXTHDR_FRAGMENT)
654 {
655 if ( (len_delta -= sizeof(struct frag_hdr)) >= 0)
656 {
657 struct frag_hdr *ip6f =
658 (struct frag_hdr *)(src+sizeof(struct ipv6hdr)+opts_len);
659
660 opts_len += sizeof(struct frag_hdr); /* Frag Header Length = 8 */
661 ip_hdr->id = htons(ntohl(ip6f->identification)); /* ID field */
662 ip_hdr->frag_off = htons((ntohs(ip6f->frag_off) & IP6F_OFF_MASK) >> 3);
663 /* fragment offset */
664 ip_hdr->frag_off = htons(ntohs(ip_hdr->frag_off) |
665 ((ntohs(ip6f->frag_off) & IP6F_MORE_FRAG) << 13));
666 /* more fragments flag */
667 next_hdr = ip6f->nexthdr;
668 }
669 else
670 {
671 PDEBUG("ip6_ip4(): fragment header error, packet droped");
672 /* Generate ICMP Parameter Problem */
673 return -1;
674 }
675 }
676 /* No Next Header */
677 else if (next_hdr == NEXTHDR_NONE)
678 {
679 /* RFC 2460 IPv6 Specification, 4.7
680 4.7 No Next Header
681
682 The value 59 in the Next Header field of an IPv6 header or any
683 extension header indicates that there is nothing following that
684 header. If the Payload Length field of the IPv6 header indicates the
685 presence of octets past the end of a header whose Next Header field
686 contains 59, those octets must be ignored, and passed on unchanged if
687 the packet is forwarded.
688 */
689 break;
690 }
691 else if (next_hdr == NEXTHDR_ESP || next_hdr == NEXTHDR_AUTH)
692 {
693 PDEBUG("ip6_ip4(): cannot translate AUTH or ESP extention header, packet dropped\n");
694 return -1;
695 }
696 else if (next_hdr == NEXTHDR_IPV6)
697 {
698 PDEBUG("ip6_ip4(): cannot translate IPv6-IPv6 packet, packet dropped\n");
699 return -1;
700 }
701 else if (next_hdr == 0)
702 {
703 /* As say RFC 2460 (IPv6 Spec) we should discard the packet and send an
704 ICMP Parameter Problem message to the source of the packet, with an
705 ICMP Code value of 1 ("unrecognized Next Header type encountered")
706 and the ICMP Pointer field containing the offset of the unrecognized
707 value within the original packet
708 */
709 /* NOT IMPLEMENTED */
710 PDEBUG("ip6_ip4(): NEXTHDR in extention header = 0, packet dropped\n");
711 return -1;
712 }
713 else
714 {
715 PDEBUG("ip6_ip4(): cannot translate extention header = %d, packet dropped\n", next_hdr);
716 return -1;
717 }
718 }
719 }
720 }
721 else
722 {
723 PDEBUG("ip6_ip4(): error packet len, packet dropped.\n");
724 return -1;
725 }
726
727 /* Building ipv4 packet */
728
729 ip_hdr->version = IPVERSION;
730 ip_hdr->ihl = 5;
731
732 /* TOS see comment about TOS in ip4_ip6() */
733 if (tos_ignore_flag)
734 ip_hdr->tos = 0;
735 else {
736 ip_hdr->tos = ip6_hdr->priority << 4;
737 ip_hdr->tos = ip_hdr->tos | (ip6_hdr->flow_lbl[0] >> 4);
738 }
739
740 /* IPv4 Total Len = IPv6 Payload Len +
741 IPv4 Header Len (without options) - Options Headers Len */
742 ip6_payload_len = ntohs(ip6_hdr->payload_len);
743
744 if (ip6_payload_len == 0)
745 ntot_len = 0;
746 else
747 ntot_len = ip6_payload_len + IP4_IP6_HDR_DIFF - opts_len;
748
749 ip_hdr->tot_len = htons(ntot_len);
750
751 /* IPv4 TTL = IPv6 Hop Limit */
752 ip_hdr->ttl = ip6_hdr->hop_limit;
753
754 /* IPv4 Protocol = Next Header that will point to upper layer protocol */
755 ip_hdr->protocol = next_hdr;
756
757 /* IPv4 Src addr = last 4 bytes from IPv6 Src addr */
758 ip_hdr->saddr = ip6_hdr->saddr.s6_addr32[3];
759 /* IPv4 Dst addr = last 4 bytes from IPv6 Dst addr */
760 ip_hdr->daddr = ip6_hdr->daddr.s6_addr32[3];
761
762 /* Calculate IPv4 header checksum */
763 ip_hdr->check = 0;
764 ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
765
766 if (len_delta > 0)
767 {
768 /* PROCESS ICMP */
769
770 if (next_hdr == NEXTHDR_ICMP)
771 {
772 struct icmp6hdr *icmp6_hdr;
773 struct icmphdr *icmp_hdr;
774
775 if ((len_delta -= sizeof(struct icmp6hdr)) >= 0)
776 {
777 icmp6_hdr = (struct icmp6hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
778 icmp_hdr = (struct icmphdr *)(dst + sizeof(struct iphdr));
779
780 real_len += len_delta + sizeof(struct icmphdr);
781
782 /* There is diffirent between ICMPv4/ICMPv6 protocol codes
783 IPPROTO_ICMP = 1
784 IPPROTO_ICMPV6 = 58 */
785 ip_hdr->protocol = IPPROTO_ICMP;
786
787 if (include_flag) {
788 /* !!! Warnig !!! We discard ICMP packets with any ICMP as included
789 in ICMP Error. But ICMP Error messages can include ICMP Query message
790 */
791 if (icmp6_hdr->icmp6_type != ICMPV6_ECHO_REQUEST)
792 {
793 PDEBUG("ip6_ip4(): included ICMPv6 in ICMPv6 Error message, packet dropped\n");
794 return -1;
795 }
796 }
797
798 /* Translate ICMPv6 to ICMPv4 */
799 switch (icmp6_hdr->icmp6_type)
800 {
801 /* ICMP Error messages */
802 /* Destination Unreachable (Type 1) */
803 case ICMPV6_DEST_UNREACH: /* Type 1 */
804 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
805 icmp_hdr->un.echo.id = 0;
806 icmp_hdr->un.echo.sequence = 0;
807 switch (icmp6_hdr->icmp6_code)
808 {
809 case ICMPV6_NOROUTE: /* Code 0 */
810 case ICMPV6_NOT_NEIGHBOUR: /* Code 2 */
811 case ICMPV6_ADDR_UNREACH: /* Code 3 */
812 icmp_hdr->code = ICMP_HOST_UNREACH; /* To Code 1 */
813 break;
814 case ICMPV6_ADM_PROHIBITED: /* Code 1 */
815 icmp_hdr->code = ICMP_HOST_ANO; /* To Code 10 */
816 break;
817 case ICMPV6_PORT_UNREACH: /* Code 4 */
818 icmp_hdr->code = ICMP_PORT_UNREACH; /* To Code 3 */
819
820 break;
821 default: /* discard any other codes */
822 PDEBUG("ip6_ip4(): Unknown ICMPv6 Type %d Code %d - packet dropped.\n",
823 ICMPV6_DEST_UNREACH, icmp6_hdr->icmp6_code);
824 return -1;
825 }
826 break;
827 /* Packet Too Big (Type 2) */
828 case ICMPV6_PKT_TOOBIG: /* Type 2 */
829 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
830 icmp_hdr->code = ICMP_FRAG_NEEDED; /* to Code 4 */
831 /* Change MTU, RFC 2765 (SIIT), 4.2:
832 The MTU field needs to be adjusted for the difference between
833 the IPv4 and IPv6 header sizes taking into account whether or
834 not the packet in error includes a Fragment header.
835 */
836 /* !!! Don't implement !!! */
837 icmp_hdr->un.frag.mtu = (__u16) icmp6_hdr->icmp6_mtu;
838 break;
839 /* Time Exceeded (Type 3) */
840 case ICMPV6_TIME_EXCEED:
841 icmp_hdr->type = ICMP_TIME_EXCEEDED; /* to Type 11 */
842 icmp_hdr->code = icmp6_hdr->icmp6_code; /* Code unchanged */
843 break;
844 /* Parameter Problem (Type 4) */
845 case ICMPV6_PARAMPROB:
846 switch (icmp6_hdr->icmp6_code) {
847 case ICMPV6_UNK_NEXTHDR: /* Code 1 */
848 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
849 icmp_hdr->code = ICMP_PROT_UNREACH; /* to Code 2 */
850 break;
851 default: /* if Code != 1 */
852 icmp_hdr->type = ICMP_PARAMETERPROB; /* to Type 12 */
853 icmp_hdr->code = 0; /* to Code 0 */
854 /* Update Pointer field
855 RFC 2765 (SIIT), 4.2:
856 The Pointer needs to be updated to point to the corresponding
857 field in the translated include IP header.
858 */
859 switch (ntohl(icmp6_hdr->icmp6_pointer))
860 {
861 case 0: /* IPv6 Version -> IPv4 Version */
862 icmp_hdr->un.echo.id = 0;
863 break;
864 case 4: /* IPv6 PayloadLength -> IPv4 Total Length */
865 icmp_hdr->un.echo.id = 0x0002; /* 2 */
866 break;
867 case 6: /* IPv6 Next Header-> IPv4 Protocol */
868 icmp_hdr->un.echo.id = 0x0009; /* 9 */
869 break;
870 case 7: /* IPv6 Hop Limit -> IPv4 TTL */
871 icmp_hdr->un.echo.id = 0x0008; /* 8 */
872 break;
873 case 8: /* IPv6 Src addr -> IPv4 Src addr */
874 icmp_hdr->un.echo.id = 0x000c; /* 12 */
875 break;
876 case 24: /* IPv6 Dst addr -> IPv4 Dst addr*/
877 icmp_hdr->un.echo.id = 0x0010; /* 16 */
878 break;
879 default: /* set all ones in other cases */
880 icmp_hdr->un.echo.id = 0xff;
881 break;
882 }
883 break;
884 }
885 break;
886
887 /* End of ICMP Error messages */
888
889 /* Echo Request and Echo Reply (Type 128 and 129) */
890 case ICMPV6_ECHO_REQUEST:
891 icmperr = 0; /* not error ICMP message */
892 icmp_hdr->type = ICMP_ECHO; /* to Type 8 */
893 icmp_hdr->code = 0; /* to Code 0 */
894 icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
895 icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
896 /* copy rest of ICMP data to result packet */
897 if (len_delta > 0)
898 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
899 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
900 break;
901 case ICMPV6_ECHO_REPLY:
902 icmperr = 0; /* not error ICMP message */
903 icmp_hdr->type = ICMP_ECHOREPLY; /* to Type 0 */
904 icmp_hdr->code = 0; /* to Code 0 */
905 icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
906 icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
907 /* copy rest of ICMP data */
908 if (len_delta > 0)
909 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
910 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
911 break;
912 default:
913 /* Unknown error messages. Silently drop. */
914 PDEBUG("ip6_ip4(): unknown ICMPv6 Type %d, packet dropped.\n", icmp6_hdr->icmp6_type);
915 return -1;
916 }
917
918 if (icmperr)
919 {
920 /* If ICMP Error message, we translate IP included packet*/
921 if (len_delta >= sizeof(struct ipv6hdr))
922 {
923 if((inc_opts_len = ip6_ip4((char *)icmp6_hdr + sizeof(struct icmp6hdr), len_delta,
924 (char *)icmp_hdr + sizeof(struct icmphdr), 1)) == -1) {
925 PDEBUG("ip6_ip4(): incorrect translation of ICMPv6 Error message, packet dropped\n");
926 return -1;
927 }
928 /* correct IPv4 Total Len that = old Total Len
929 - Options Headers Len in included IP packet
930 - diffirence between IPv6 Header Len and IPv4 Header Len
931 */
932 if (ntot_len != 0)
933 ip_hdr->tot_len = htons(ntot_len - inc_opts_len - IP4_IP6_HDR_DIFF);
934 real_len = real_len - inc_opts_len - IP4_IP6_HDR_DIFF;
935 }
936 else if (len_delta > 0)
937 {
938 /* May be it need set 0x0 to rest area in result IPv4 packet,
939 * but we copy rest data unchanged
940 */
941 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
942 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
943 }
944 }
945
946 /* Calculate IPv4 Header checksum */
947 ip_hdr->check = 0;
948 ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
949
950 /* Calculate ICMPv4 checksum */
951 if (ntot_len != 0)
952 {
953 icmp_hdr->checksum = 0;
954 icmp_hdr->checksum = ip_compute_csum((unsigned char *)icmp_hdr, ntohs(ip_hdr->tot_len)
955 - sizeof(struct iphdr));
956 }
957 }
958 else
959 {
960 PDEBUG("ip6_ip4(): error length ICMP packet, packet dropped.\n");
961 return -1;
962 }
963
964 }
965 /* PROCESS TCP and UDP (and rest data) */
966
967 else {
968 real_len += len_delta;
969 /* we copy rest data to IPv4 packet without changing */
970 memcpy(dst+sizeof(struct iphdr), src + sizeof(struct ipv6hdr) + opts_len, len_delta);
971 }
972 }
973
974 if (include_flag) /* if it's included IP packet */
975 return opts_len; /* return options headers length */
976 else
977 return real_len; /* result packet len */
978 }
979
980 /*
981 * ip4_fragment(skb, len, hdr_len, dev, eth_h)
982 * to fragment original IPv4 packet if result IPv6 packet will be > 1280
983 */
984
985 static int ip4_fragment(struct sk_buff *skb, int len, int hdr_len, struct net_device *dev, struct ethhdr *eth_h)
986 {
987 struct sk_buff *skb2 = NULL; /* pointer to new struct sk_buff for transleded packet */
988 char buff[FRAG_BUFF_SIZE+hdr_len]; /* buffer to form new fragment packet */
989 char *cur_ptr = skb->data+hdr_len; /* pointter to current packet data with len = frag_len */
990 struct iphdr *ih4 = (struct iphdr *) skb->data;
991 struct iphdr *new_ih4 = (struct iphdr *) buff; /* point to new IPv4 hdr */
992 struct ethhdr *new_eth_h; /* point to ether hdr, need to set hard header data in fragment */
993 int data_len = len - hdr_len; /* origin packet data len */
994 int rest_len = data_len; /* rest data to fragment */
995 int frag_len = 0; /* current fragment len */
996 int last_frag = 0; /* last fragment flag, if = 1, it's last fragment */
997 int flag_last_mf = 0;
998 __u16 new_id = 0; /* to generate identification field */
999 __u16 frag_offset = 0; /* fragment offset */
1000 unsigned int csum;
1001 unsigned short udp_len;
1002
1003 #ifdef SIIT_DEBUG
1004 printk("siit: it's DF == 0 and result IPv6 packet will be > 1280\n");
1005 siit_print_dump(skb->data, hdr_len, "siit: (orig) ipv4_hdr dump");
1006 #endif
1007
1008 if ((ntohs(ih4->frag_off) & IP_MF) == 0 )
1009 /* it's a case we'll clear MF flag in our last packet */
1010 flag_last_mf = 1;
1011
1012 if (ih4->protocol == IPPROTO_UDP) {
1013 if ( (ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
1014 struct udphdr *udp_hdr = (struct udphdr *)((char *)ih4 + hdr_len);
1015 if (!flag_last_mf) {
1016 if (udp_hdr->check == 0) {
1017 /* it's a first fragment with ZERO checksum and we drop packet */
1018 printk("siit: First fragment of UDP with zero checksum - packet droped\n");
1019 printk("siit: addr: %x src port: %d dst port: %d\n",
1020 htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
1021 return -1;
1022 }
1023 }
1024 else if (udp_hdr->check == 0) {
1025 /* Calculate UDP checksum only if it's not fragment */
1026 udp_len = ntohs(udp_hdr->len);
1027 csum = 0;
1028 csum = csum_partial((unsigned char *)udp_hdr, udp_len, csum);
1029 udp_hdr->check = csum_tcpudp_magic(ih4->saddr, ih4->daddr, udp_len, IPPROTO_UDP, csum);
1030 }
1031 }
1032 }
1033
1034 frag_offset = ntohs(ih4->frag_off) & IP_OFFSET;
1035
1036 new_id = ih4->id;
1037
1038 while(1) {
1039 if (rest_len <= FRAG_BUFF_SIZE) {
1040 /* it's last fragmen */
1041 frag_len = rest_len; /* rest data */
1042 last_frag = 1;
1043 }
1044 else
1045 frag_len = FRAG_BUFF_SIZE;
1046
1047 /* copy IP header to buffer */
1048 memcpy(buff, skb->data, hdr_len);
1049 /* copy data to buffer with len = frag_len */
1050 memcpy(buff + hdr_len, cur_ptr, frag_len);
1051
1052 /* set id field in new IPv4 header*/
1053 new_ih4->id = new_id;
1054
1055 /* is it last fragmet */
1056 if(last_frag && flag_last_mf)
1057 /* clear MF flag */
1058 new_ih4->frag_off = htons(frag_offset & (~IP_MF));
1059 else
1060 /* set MF flag */
1061 new_ih4->frag_off = htons(frag_offset | IP_MF);
1062
1063 /* change packet total length */
1064 new_ih4->tot_len = htons(frag_len+hdr_len);
1065
1066 /* rebuild the header checksum (IP needs it) */
1067 new_ih4->check = 0;
1068 new_ih4->check = ip_fast_csum((unsigned char *)new_ih4,new_ih4->ihl);
1069
1070 /* Allocate new sk_buff to compose translated packet */
1071 skb2 = dev_alloc_skb(frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE);
1072 if (!skb2) {
1073 printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1074 dev_kfree_skb(skb2);
1075 return -1;
1076 }
1077 /* allocate skb->data portion for IP header len, fragment data len and ether header len
1078 * and copy to head ether header from origin skb
1079 */
1080 memcpy(skb_put(skb2, frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE), (char *) eth_h,
1081 dev->hard_header_len);
1082 /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1083 new_eth_h = (struct ethhdr *)skb2->data;
1084 new_eth_h->h_proto = htons(ETH_P_IPV6);
1085
1086 /* reset the mac header */
1087 skb_reset_mac_header(skb2);
1088
1089 /* pull ether header from new skb->data */
1090 skb_pull(skb2, dev->hard_header_len);
1091 /* set skb protocol to IPV6 */
1092 skb2->protocol = htons(ETH_P_IPV6);
1093
1094 /* call translation function */
1095 if ( ip4_ip6(buff, frag_len+hdr_len, skb2->data, 0) == -1) {
1096 dev_kfree_skb(skb2);
1097 return -1;
1098 }
1099
1100 /*
1101 * Set needed fields in new sk_buff
1102 */
1103 skb2->dev = dev;
1104 skb2->ip_summed = CHECKSUM_UNNECESSARY;
1105 skb2->pkt_type = PACKET_HOST;
1106
1107 /* Add transmit statistic */
1108 siit_stats(dev)->tx_packets++;
1109 siit_stats(dev)->tx_bytes += skb2->len;
1110
1111 /* send packet to upper layer */
1112 netif_rx(skb2);
1113
1114 /* exit if it was last fragment */
1115 if (last_frag)
1116 break;
1117
1118 /* correct current data pointer */
1119 cur_ptr += frag_len;
1120 /* rest data len */
1121 rest_len -= frag_len;
1122 /* current fragment offset */
1123 frag_offset = (frag_offset*8 + frag_len)/8;
1124 }
1125
1126 return 0;
1127 }
1128 /*
1129 * Transmit a packet (called by the kernel)
1130 *
1131 * siit_xmit(skb, dev)
1132 *
1133 * where
1134 * skb - pointer to struct sk_buff with incomed packet
1135 * dev - pointer to struct device on which packet revieved
1136 *
1137 * Statistic:
1138 * for all incoming packes:
1139 * stats.rx_bytes+=skb->len
1140 * stats.rx_packets++
1141 * for packets we can't transle:
1142 * stats.tx_errors++
1143 * device busy:
1144 * stats.tx_errors++
1145 * for packets we can't allocate sk_buff:
1146 * stats.tx_dropped++
1147 * for outgoing packes:
1148 * stats.tx_packets++
1149 * stats.tx_bytes+=skb2->len !!! But we don't set skb2->len !!!
1150 */
1151
1152 static int siit_xmit(struct sk_buff *skb, struct net_device *dev)
1153 {
1154 struct sk_buff *skb2 = NULL;/* pointer to new struct sk_buff for transleded packet */
1155 struct ethhdr *eth_h; /* pointer to incoming Ether header */
1156 int len; /* original packets length */
1157 int new_packet_len;
1158 int skb_delta = 0; /* delta size for allocate new skb */
1159 char new_packet_buff[2048];
1160
1161 /* Check pointer to sk_buff and device structs */
1162 if (skb == NULL || dev == NULL)
1163 return -EINVAL;
1164
1165 /* Add receive statistic */
1166 siit_stats(dev)->rx_bytes += skb->len;
1167 siit_stats(dev)->rx_packets++;
1168
1169 dev->trans_start = jiffies;
1170
1171 /* Upper layer (IP) protocol forms sk_buff for outgoing packet
1172 * and sets IP header + Ether header too. IP layer sets outgoing
1173 * device in sk_buff->dev.
1174 * In function (from linux/net/core/dev.c) ther is a call to
1175 * device transmit function (dev->hard_start_xmit):
1176 *
1177 * dev_queue_xmit(struct sk_buff *skb)
1178 * {
1179 * ...
1180 * device *dev = skb->dev;
1181 * ...
1182 * dev->hard_start_xmit(skb, dev);
1183 * ...
1184 * }
1185 * We save pointer to ether header in eth_h and skb_pull ether header
1186 * from data field of skb_buff
1187 */
1188
1189 eth_h = (struct ethhdr *)skb->data; /* point to incoming packet Ether Header */
1190
1191 #ifdef SIIT_DEBUG
1192 siit_print_dump(skb->data, ETH_HLEN, "siit: eth_hdr dump");
1193 #endif
1194
1195 /* Remove hardware header from origin sk_buff */
1196 skb_pull(skb,dev->hard_header_len);
1197
1198 /*
1199 * Process IPv4 paket
1200 */
1201 if (ntohs(skb->protocol) == ETH_P_IP) {
1202 int hdr_len; /* IPv4 header length */
1203 int data_len; /* IPv4 data length */
1204 struct iphdr *ih4; /* pointer to IPv4 header */
1205 struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
1206
1207 ih4 = (struct iphdr *)skb->data; /* point to incoming packet's IPv4 header */
1208
1209 /* Check IPv4 Total Length */
1210 if (skb->len != ntohs(ih4->tot_len)) {
1211 PDEBUG("siit_xmit(): Different skb_len %x and ip4 tot_len %x - packet dropped.\n",
1212 skb->len, ih4->tot_len);
1213 siit_stats(dev)->tx_errors++;
1214 dev_kfree_skb(skb);
1215 return 0;
1216 }
1217
1218 len = skb->len; /* packet's total len */
1219 hdr_len = (int)(ih4->ihl * 4); /* packet's header len */
1220 data_len = len - hdr_len; /* packet's data len */
1221
1222 /* If DF == 0 */
1223 if ( (ntohs(ih4->frag_off) & IP_DF) == 0 ) {
1224 /* If result IPv6 packet will be > 1280
1225 we need to fragment original IPv4 packet
1226 */
1227 if ( data_len > FRAG_BUFF_SIZE ) {
1228 /* call function that fragment packet and translate to IPv6 each fragment
1229 * and send to upper layer
1230 */
1231 if ( ip4_fragment(skb, len, hdr_len, dev, eth_h) == -1) {
1232 siit_stats(dev)->tx_errors++;
1233 }
1234 /* Free incoming skb */
1235 dev_kfree_skb(skb);
1236 /* Device can accept a new packet */
1237
1238 return 0;
1239
1240 }
1241 }
1242 /* If DF == 1 && MF == 0 && Fragment Offset == 0
1243 * we don't include fragment header
1244 */
1245 if ( ntohs(ih4->frag_off) == IP_DF )
1246 skb_delta = IP4_IP6_HDR_DIFF; /* delta is +20 */
1247 else
1248 skb_delta = IP4_IP6_HDR_DIFF + IP6_FRAGMENT_SIZE; /* delta is +20 and +8 */
1249
1250 /* If it's ICMP, check is it included IP packet in it */
1251 if ( ih4->protocol == IPPROTO_ICMP) {
1252 icmp_hdr = (struct icmphdr *) (skb->data+hdr_len); /* point to ICMPv4 header */
1253 if ( icmp_hdr->type != ICMP_ECHO && icmp_hdr->type != ICMP_ECHOREPLY) {
1254 /*
1255 * It's ICMP Error that has included IP packet
1256 * we'll add only +20 because we don't include Fragment Header
1257 * into translated included IP packet
1258 */
1259 skb_delta += IP4_IP6_HDR_DIFF;
1260 }
1261 }
1262
1263 /* Allocate new sk_buff to compose translated packet */
1264 skb2 = dev_alloc_skb(len+dev->hard_header_len+skb_delta);
1265 if (!skb2) {
1266 printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1267 dev_kfree_skb(skb);
1268 siit_stats(dev)->rx_dropped++;
1269
1270 return 0;
1271 }
1272 /* allocate skb->data portion = IPv4 packet len + ether header len
1273 * + skb_delta (max = two times (diffirence between IPv4 header and
1274 * IPv6 header + Frag Header), second for included packet,
1275 * and copy to head of skb->data ether header from origin skb
1276 */
1277 memcpy(skb_put(skb2, len+dev->hard_header_len+skb_delta), (char *)eth_h, dev->hard_header_len);
1278 /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1279 eth_h = (struct ethhdr *)skb2->data;
1280 eth_h->h_proto = htons(ETH_P_IPV6);
1281 skb_reset_mac_header(skb2);
1282 /* remove ether header from new skb->data,
1283 * NOTE! data will rest, pointer to data and data len will change
1284 */
1285 skb_pull(skb2,dev->hard_header_len);
1286 /* set skb protocol to IPV6 */
1287 skb2->protocol = htons(ETH_P_IPV6);
1288
1289 /* call translation function */
1290 if (ip4_ip6(skb->data, len, skb2->data, 0) == -1 ) {
1291 dev_kfree_skb(skb);
1292 dev_kfree_skb(skb2);
1293 siit_stats(dev)->rx_errors++;
1294
1295 return 0;
1296 }
1297 }
1298 /*
1299 * IPv6 paket
1300 */
1301 else if (ntohs(skb->protocol) == ETH_P_IPV6) {
1302
1303 #ifdef SIIT_DEBUG
1304 siit_print_dump(skb->data, sizeof(struct ipv6hdr), "siit: (in) ip6_hdr dump");
1305 #endif
1306 /* packet len = skb->data len*/
1307 len = skb->len;
1308
1309 /* call translation function */
1310 if ((new_packet_len = ip6_ip4(skb->data, len, new_packet_buff, 0)) == -1 )
1311 {
1312 PDEBUG("siit_xmit(): error translation ipv6->ipv4, packet dropped.\n");
1313 siit_stats(dev)->rx_dropped++;
1314 goto end;
1315 }
1316
1317 /* Allocate new sk_buff to compose translated packet */
1318 skb2 = dev_alloc_skb(new_packet_len + dev->hard_header_len);
1319 if (!skb2) {
1320 printk(KERN_DEBUG "%s: alloc_skb failure, packet dropped.\n", dev->name);
1321 siit_stats(dev)->rx_dropped++;
1322 goto end;
1323 }
1324 memcpy(skb_put(skb2, new_packet_len + dev->hard_header_len), (char *)eth_h, dev->hard_header_len);
1325 eth_h = (struct ethhdr *)skb2->data;
1326 eth_h->h_proto = htons(ETH_P_IP);
1327 skb_reset_mac_header(skb2);
1328 skb_pull(skb2, dev->hard_header_len);
1329 memcpy(skb2->data, new_packet_buff, new_packet_len);
1330 skb2->protocol = htons(ETH_P_IP);
1331 }
1332 else {
1333 PDEBUG("siit_xmit(): unsupported protocol family %x, packet dropped.\n", skb->protocol);
1334 goto end;
1335 }
1336
1337 /*
1338 * Set needed fields in new sk_buff
1339 */
1340 skb2->pkt_type = PACKET_HOST;
1341 skb2->dev = dev;
1342 skb2->ip_summed = CHECKSUM_UNNECESSARY;
1343
1344 /* Add transmit statistic */
1345 siit_stats(dev)->tx_packets++;
1346 siit_stats(dev)->tx_bytes += skb2->len;
1347
1348 /* Send packet to upper layer protocol */
1349 netif_rx(skb2);
1350
1351 end:
1352 dev_kfree_skb(skb);
1353
1354 return 0;
1355 }
1356
1357 static bool header_ops_init = false;
1358 static struct header_ops siit_header_ops ____cacheline_aligned;
1359
1360 static const struct net_device_ops siit_netdev_ops = {
1361 .ndo_open = siit_open,
1362 .ndo_stop = siit_release,
1363 .ndo_start_xmit = siit_xmit,
1364 };
1365
1366 /*
1367 * The init function initialize of the SIIT device..
1368 * It is invoked by register_netdev()
1369 */
1370
1371 static void
1372 siit_init(struct net_device *dev)
1373 {
1374 ether_setup(dev); /* assign some of the fields */
1375 random_ether_addr(dev->dev_addr);
1376
1377 /*
1378 * Assign device function.
1379 */
1380 dev->netdev_ops = &siit_netdev_ops;
1381 dev->flags |= IFF_NOARP; /* ARP not used */
1382 dev->tx_queue_len = 10;
1383
1384 if (!header_ops_init) {
1385 memcpy(&siit_header_ops, dev->header_ops, sizeof(struct header_ops));
1386 siit_header_ops.cache = NULL;
1387 }
1388 dev->header_ops = &siit_header_ops;
1389 }
1390
1391 /*
1392 * Finally, the module stuff
1393 */
1394 static struct net_device *siit_dev = NULL;
1395
1396 int init_module(void)
1397 {
1398 int res = -ENOMEM;
1399 int priv_size;
1400
1401 priv_size = sizeof(struct header_ops);
1402 siit_dev = alloc_netdev(priv_size, "siit%d", siit_init);
1403 if (!siit_dev)
1404 goto err_alloc;
1405
1406 res = register_netdev(siit_dev);
1407 if (res)
1408 goto err_register;
1409
1410 return 0;
1411
1412 err_register:
1413 free_netdev(siit_dev);
1414 err_alloc:
1415 printk(KERN_ERR "Error creating siit device: %d\n", res);
1416 return res;
1417 }
1418
1419 void cleanup_module(void)
1420 {
1421 unregister_netdev(siit_dev);
1422 free_netdev(siit_dev);
1423 }
1424
1425 MODULE_LICENSE("GPL");
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