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[openwrt.git] / package / siit / src / siit.c
1 /*
2 * siit.c: the Stateless IP/ICMP Translator (SIIT) module for Linux.
3 *
4 *
5 */
6
7 #include <linux/autoconf.h>
8 #include <linux/module.h>
9 #include <linux/version.h>
10 #include <linux/sched.h>
11 #include <linux/kernel.h> /* printk() */
12 #include <linux/slab.h>
13
14 #include <linux/errno.h> /* error codes */
15 #include <linux/types.h> /* size_t */
16 #include <linux/interrupt.h> /* mark_bh */
17 #include <linux/random.h>
18 #include <linux/in.h>
19 #include <linux/netdevice.h> /* struct device, and other headers */
20 #include <linux/etherdevice.h> /* eth_type_trans */
21 #include <net/ip.h> /* struct iphdr */
22 #include <net/icmp.h> /* struct icmphdr */
23 #include <net/ipv6.h>
24 #include <net/udp.h>
25 #include <linux/skbuff.h>
26 #include <linux/in6.h>
27 #include <linux/init.h>
28 #include <asm/uaccess.h>
29 #include <asm/checksum.h>
30 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0)
31 #include <net/ip6_checksum.h>
32 #endif
33 #include <linux/in6.h>
34 #include "siit.h"
35
36 MODULE_AUTHOR("Dmitriy Moscalev, Grigory Klyuchnikov, Felix Fietkau");
37
38 /*
39 * If tos_ignore_flag != 0, we don't copy TOS and Traffic Class
40 * from origin paket and set it to 0
41 */
42 int tos_ignore_flag = 0;
43
44 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
45 static inline void
46 skb_reset_mac_header(struct sk_buff *skb)
47 {
48 skb->mac.raw=skb->data;
49 }
50
51 static struct net_device_stats *
52 siit_get_stats(struct net_device *dev)
53 {
54 return netdev_priv(dev);
55 }
56
57 static inline void random_ether_addr(u8 *addr)
58 {
59 get_random_bytes (addr, ETH_ALEN);
60 addr [0] &= 0xfe; /* clear multicast bit */
61 addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
62 }
63
64
65 #define siit_stats(_dev) ((struct net_device_stats *)netdev_priv(_dev))
66 #else
67 #define siit_stats(_dev) (&(_dev)->stats)
68 #endif
69
70 /*
71 * The Utility stuff
72 */
73
74 #ifdef SIIT_DEBUG
75 /* print dump bytes (data point data area sizeof len and message
76 * before dump.
77 */
78 static int siit_print_dump(char *data, int len, char *message)
79 {
80 int i;
81 int j = 0, k = 1;
82
83 len = len > BUFF_SIZE ? BUFF_SIZE : len;
84 printk("%s:\n", message);
85 for (i=0; i < len; i++, k++) {
86 if( i == len-1 || k == 16) {
87 printk("%02x\n", (~(~0 << 8) & *(data+i)));
88 j = 0;
89 k = 0;
90 }
91 else if (j) {
92 printk("%02x ", (~(~0 << 8) & *(data+i)));
93 j--;
94 }
95 else {
96 printk("%02x", (~(~0 << 8) & *(data+i)));
97 j++;
98 }
99 }
100 return 0;
101 }
102 #endif
103
104 /*
105 * Open and close
106 */
107 static int siit_open(struct net_device *dev)
108 {
109 netif_start_queue(dev);
110 return 0;
111 }
112
113
114 static int siit_release(struct net_device *dev)
115 {
116 netif_stop_queue(dev); /* can't transmit any more */
117 return 0;
118 }
119
120 /*
121 * Translation IPv4 to IPv6 stuff
122 *
123 * ip4_ip6 (src, len, dst, include_flag)
124 *
125 * where
126 * src - buffer with original IPv4 packet,
127 * len - size of original packet,
128 * dst - new buffer for IPv6 packet,
129 * include_flag - if = 1, dst point to IPv4 packet that is ICMP error
130 * included IP packet, else = 0
131 */
132
133 static int ip4_ip6(char *src, int len, char *dst, int include_flag)
134 {
135 struct iphdr *ih4 = (struct iphdr *) src; /* point to current IPv4 header struct */
136 struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
137 struct udphdr *udp_hdr; /* point to current IPv4 UDP header struct */
138
139 struct ipv6hdr *ih6 = (struct ipv6hdr *) dst; /* point to current IPv6 header struct */
140 struct frag_hdr *ih6_frag = (struct frag_hdr *)(dst+sizeof(struct ipv6hdr));
141 /* point to current IPv6 fragment header struct */
142 struct icmp6hdr *icmp6_hdr; /* point to current ICMPv6 header */
143
144 int hdr_len = (int)(ih4->ihl * 4); /* IPv4 header length */
145 int icmp_len; /* ICMPv4 packet length */
146 int plen; /* payload length */
147
148 unsigned int csum; /* need to calculate ICMPv6 and UDP checksum */
149 int fl_csum = 0; /* flag to calculate UDP checksum */
150 int icmperr = 1; /* flag to indicate ICMP error message and to need
151 translate ICMP included IP packet */
152 int fr_flag = 0; /* fragment flag, if = 0 - don't add
153 fragment header */
154 __u16 new_tot_len; /* need to calculate IPv6 total length */
155 __u8 new_nexthdr; /* next header code */
156 __u16 icmp_ptr = 0; /* Pointer field in ICMP_PARAMETERPROB */
157
158 #ifdef SIIT_DEBUG /* print IPv4 header dump */
159 siit_print_dump(src, hdr_len, "siit: ip4_ip6() (in) ip4 header dump");
160 #endif
161
162 /* If DF == 1 && MF == 0 && Fragment Offset == 0
163 * or this packet is ICMP included IP packet
164 * we don't need fragment header */
165 if (ntohs(ih4->frag_off) == IP_DF || include_flag ) {
166 /* not fragment and we need not to add Fragment
167 * Header to IPv6 packet. */
168 /* total length = total length from IPv4 packet */
169 new_tot_len = ntohs(ih4->tot_len);
170
171 if (ih4->protocol == IPPROTO_ICMP)
172 new_nexthdr = NEXTHDR_ICMP;
173 else
174 new_nexthdr = ih4->protocol;
175 }
176 else {
177 /* need to add Fragment Header */
178 fr_flag = 1;
179 /* total length = total length from IPv4 packet +
180 length of Fragment Header */
181 new_tot_len = ntohs(ih4->tot_len) + sizeof(struct frag_hdr);
182 /* IPv6 Header NextHeader = NEXTHDR_FRAGMENT */
183 new_nexthdr = NEXTHDR_FRAGMENT;
184 /* Fragment Header NextHeader copy from IPv4 packet */
185 if (ih4->protocol == IPPROTO_ICMP)
186 ih6_frag->nexthdr = NEXTHDR_ICMP;
187 else
188 ih6_frag->nexthdr = ih4->protocol;
189
190 /* copy frag offset from IPv4 packet */
191 ih6_frag->frag_off = htons((ntohs(ih4->frag_off) & IP_OFFSET) << 3);
192 /* copy MF flag from IPv4 packet */
193 ih6_frag->frag_off = htons((ntohs(ih6_frag->frag_off) |
194 ((ntohs(ih4->frag_off) & IP_MF) >> 13)));
195 /* copy Identification field from IPv4 packet */
196 ih6_frag->identification = htonl(ntohs(ih4->id));
197 /* reserved field initialized to zero */
198 ih6_frag->reserved = 0;
199 }
200
201 /* Form rest IPv6 fields */
202
203 /*
204 * At this point we need to add checking of unxpired source
205 * route optin and if it is, send ICMPv4 "destination
206 * unreacheble/source route failes" Type 3/Code 5 and
207 * drop packet. (NOT RELEASED YET)
208 */
209
210 /* IP version = 6 */
211 ih6->version = 6;
212
213 if (tos_ignore_flag) {
214 ih6->priority = 0;
215 ih6->flow_lbl[0] = 0;
216 } else {
217 ih6->priority = (ih4->tos & 0xf0) >> 4;
218 ih6->flow_lbl[0] = (ih4->tos & 0x0f) << 4;
219 }
220 ih6->flow_lbl[1] = 0;
221 ih6->flow_lbl[2] = 0;
222
223 /* Hop Limit = IPv4 TTL */
224 ih6->hop_limit = ih4->ttl;
225
226 /* Translate source destination addresses,
227 for IPv6 host it's IPv4-translated IPv6 address,
228 for IPv4 host it's IPv4-mapped IPv6 address
229
230 !!WARNING!! Instead IPv4-mapped IPv6 addresses we use addreesses
231 with unused prefix ::ffff:ffff:0:0/96, because KAME implementation
232 doesn't support IPv4-mapped addresses in IPv6 packets and discard them.
233
234 */
235
236 if (include_flag) {
237 /*
238 It's ICMP included IP packet and there is a diffirence
239 in src/dst addresses then src/dst in normal direction
240 */
241
242 /*
243 Source address
244 is IPv4-translated IPv6 address because packet traveled
245 from IPv6 to IPv4 area
246 */
247 ih6->saddr.in6_u.u6_addr32[0] = 0;
248 ih6->saddr.in6_u.u6_addr32[1] = 0;
249 ih6->saddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
250 ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
251
252 /*
253 Destination address
254 is IPv4-mapped address (but it's not IPv4- mapped, we use
255 prefix ::ffff:ffff:0:0/96
256 */
257 ih6->daddr.in6_u.u6_addr32[0] = 0;
258 ih6->daddr.in6_u.u6_addr32[1] = 0;
259 ih6->daddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
260 ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
261 }
262 else {
263
264 /*
265 This is normal case (packet isn't included IP packet)
266
267 Source address
268 is IPv4-mapped address (but it's not IPv4- mapped, we use
269 prefix ::ffff:ffff:0:0/96)
270 */
271 ih6->saddr.in6_u.u6_addr32[0] = 0;
272 ih6->saddr.in6_u.u6_addr32[1] = 0;
273 ih6->saddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
274 ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
275
276 /* Destination address
277 is is IPv4-translated IPv6 address
278 */
279 ih6->daddr.in6_u.u6_addr32[0] = 0;
280 ih6->daddr.in6_u.u6_addr32[1] = 0;
281 ih6->daddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
282 ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
283 }
284
285 /* Payload Length */
286 plen = new_tot_len - hdr_len; /* Payload length = IPv4 total len - IPv4 header len */
287 ih6->payload_len = htons(plen);
288
289 /* Next Header */
290 ih6->nexthdr = new_nexthdr; /* Next Header */
291
292 /* Process ICMP protocols data */
293
294 switch (ih4->protocol) {
295 case IPPROTO_ICMP:
296 if ( (ntohs(ih4->frag_off) & IP_OFFSET) != 0 || (ntohs(ih4->frag_off) & IP_MF) != 0 ) {
297 PDEBUG("ip4_ip6(): don't translate ICMPv4 fragments - packet dropped.\n");
298 return -1;
299 }
300
301 icmp_hdr = (struct icmphdr *) (src+hdr_len); /* point to ICMPv4 header */
302 csum = 0;
303 icmp_len = ntohs(ih4->tot_len) - hdr_len; /* ICMPv4 packet length */
304 icmp6_hdr = (struct icmp6hdr *)(dst+sizeof(struct ipv6hdr)
305 +fr_flag*sizeof(struct frag_hdr)); /* point to ICMPv6 header */
306
307 if (include_flag) {
308 /* ICMPv4 packet cannot be included in ICMPv4 Error message */
309 /* !!! May be it's WRONG !!! ICMPv4 QUERY packet can be included
310 in ICMPv4 Error message */
311 PDEBUG("ip4_ip6(): It's included ICMPv4 in ICMPv4 Error message - packet dropped.\n");
312 return -1;
313 }
314
315 /* Check ICMPv4 Type field */
316 switch (icmp_hdr->type) {
317 /* ICMP Error messages */
318 /* Destination Unreachable (Type 3) */
319 case ICMP_DEST_UNREACH:
320 icmp6_hdr->icmp6_type = ICMPV6_DEST_UNREACH; /* to Type 1 */
321 icmp6_hdr->icmp6_unused = 0;
322 switch (icmp_hdr->code)
323 {
324 case ICMP_NET_UNREACH: /* Code 0 */
325 case ICMP_HOST_UNREACH: /* Code 1 */
326 case ICMP_SR_FAILED: /* Code 5 */
327 case ICMP_NET_UNKNOWN: /* Code 6 */
328 case ICMP_HOST_UNKNOWN: /* Code 7 */
329 case ICMP_HOST_ISOLATED: /* Code 8 */
330 case ICMP_NET_UNR_TOS: /* Code 11 */
331 case ICMP_HOST_UNR_TOS: /* Code 12 */
332 icmp6_hdr->icmp6_code = ICMPV6_NOROUTE; /* to Code 0 */
333 break;
334 case ICMP_PROT_UNREACH: /* Code 2 */
335 icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB; /* to Type 4 */
336 icmp6_hdr->icmp6_code = ICMPV6_UNK_NEXTHDR; /* to Code 1 */
337 /* Set pointer filed to 6, it's octet offset IPv6 Next Header field */
338 icmp6_hdr->icmp6_pointer = htonl(6);
339 break;
340 case ICMP_PORT_UNREACH: /* Code 3 */
341 icmp6_hdr->icmp6_code = ICMPV6_PORT_UNREACH; /* to Code 4 */
342 break;
343 case ICMP_FRAG_NEEDED: /* Code 4 */
344 icmp6_hdr->icmp6_type = ICMPV6_PKT_TOOBIG; /* to Type 2 */
345 icmp6_hdr->icmp6_code = 0;
346 /* Correct MTU */
347 if (icmp_hdr->un.frag.mtu == 0)
348 /* we use minimum MTU for IPv4 PMTUv4 RFC1191, section 5;
349 IPv6 implementation wouldn't accept Path MTU < 1280,
350 but it records info correctly to always include
351 a fragment header */
352 icmp6_hdr->icmp6_mtu = htonl(576);
353 else
354 /* needs to adjusted for difference between IPv4/IPv6 headers
355 * SIIT RFC2765, section 3.3,
356 * we assume that difference is 20 bytes */
357 icmp6_hdr->icmp6_mtu = htonl(ntohs(icmp_hdr->un.frag.mtu)+IP4_IP6_HDR_DIFF);
358
359 break;
360 case ICMP_NET_ANO: /* Code 9 */
361 case ICMP_HOST_ANO: /* Code 10 */
362 icmp6_hdr->icmp6_code = ICMPV6_ADM_PROHIBITED; /* to Code 1 */
363 break;
364 default: /* discard any other Code */
365 PDEBUG("ip4_ip6(): Unknown ICMPv4 Type %d Code %d - packet dropped.\n",
366 ICMP_DEST_UNREACH, icmp_hdr->code);
367 return -1;
368 }
369 break;
370 /* Time Exceeded (Type 11) */
371 case ICMP_TIME_EXCEEDED:
372 icmp6_hdr->icmp6_type = ICMPV6_TIME_EXCEED;
373 icmp6_hdr->icmp6_code = icmp_hdr->code;
374 break;
375 /* Parameter Problem (Type 12) */
376 case ICMP_PARAMETERPROB:
377 icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB;
378 icmp6_hdr->icmp6_code = icmp_hdr->code;
379
380 icmp_ptr = ntohs(icmp_hdr->un.echo.id) >> 8;
381 switch (icmp_ptr) {
382 case 0:
383 icmp6_hdr->icmp6_pointer = 0; /* IPv4 Version -> IPv6 Version */
384 break;
385 case 2:
386 icmp6_hdr->icmp6_pointer = __constant_htonl(4); /* IPv4 length -> IPv6 Payload Length */
387 break;
388 case 8:
389 icmp6_hdr->icmp6_pointer = __constant_htonl(7); /* IPv4 TTL -> IPv6 Hop Limit */
390 break;
391 case 9:
392 icmp6_hdr->icmp6_pointer = __constant_htonl(6); /* IPv4 Protocol -> IPv6 Next Header */
393 break;
394 case 12:
395 icmp6_hdr->icmp6_pointer = __constant_htonl(8); /* IPv4 Src Addr -> IPv6 Src Addr */
396 break;
397 case 16:
398 icmp6_hdr->icmp6_pointer = __constant_htonl(24); /* IPv4 Dst Addr -> IPv6 Dst Addr */
399 break;
400 default:
401 icmp6_hdr->icmp6_pointer = 0xffffffff; /* set to all ones in any other cases */
402 break;
403 }
404 break;
405 case ICMP_ECHO:
406 icmperr = 0;
407 icmp6_hdr->icmp6_type = ICMPV6_ECHO_REQUEST;
408 icmp6_hdr->icmp6_code = 0;
409 /* Copy rest ICMP data to new IPv6 packet without changing */
410 memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
411 break;
412
413 case ICMP_ECHOREPLY:
414 icmperr = 0;
415 icmp6_hdr->icmp6_type = ICMPV6_ECHO_REPLY;
416 icmp6_hdr->icmp6_code = 0;
417 /* Copy rest ICMP data to new IPv6 packet without changing */
418 memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
419 break;
420
421 /* Discard any other ICMP messages */
422 default:
423 PDEBUG("ip4_ip6(): Unknown ICMPv4 packet Type %x - packet dropped.\n", icmp_hdr->type);
424 return -1;
425 }
426
427 /* Now if it's ICMPv4 Error message we must translate included IP packet */
428
429 if (icmperr) {
430 /* Call our ip4_ip6() to translate included IP packet */
431 if (ip4_ip6(src+hdr_len+sizeof(struct icmphdr), len - hdr_len - sizeof(struct icmphdr),
432 dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr)
433 +sizeof(struct icmp6hdr), 1) == -1) {
434 PDEBUG("ip4_ip6(): Uncorrect translation of ICMPv4 Error message - packet dropped.\n");
435 return -1;
436 }
437 /* correct ICMPv6 packet length for diffirence between IPv4 and IPv6 headers
438 in included IP packet
439 */
440 icmp_len += 20;
441 /* and correct Payload length for diffirence between IPv4 and IPv6 headers */
442 plen += 20;
443 ih6->payload_len = htons(plen);
444 }
445
446 /* Calculate ICMPv6 checksum */
447
448 icmp6_hdr->icmp6_cksum = 0;
449 csum = 0;
450
451 csum = csum_partial((u_char *)icmp6_hdr, icmp_len, csum);
452 icmp6_hdr->icmp6_cksum = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, icmp_len,
453 IPPROTO_ICMPV6, csum);
454 break;
455
456 /* Process TCP protocols data */
457 case IPPROTO_TCP:
458 /* Copy TCP data to new IPv6 packet without changing */
459 memcpy(dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr),
460 src+hdr_len, len - hdr_len);
461 break;
462
463 /* Process UDP protocols data */
464 case IPPROTO_UDP:
465 udp_hdr = (struct udphdr *)(src+hdr_len);
466 if ((ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
467 if ((ntohs(ih4->frag_off) & IP_MF) != 0) {
468 /* It's a first fragment */
469 if (udp_hdr->check == 0) {
470 /* System management event */
471 printk("siit: First fragment of UDP with zero checksum - packet droped\n");
472 printk("siit: addr: %x src port: %d dst port: %d\n",
473 htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
474 return -1;
475 }
476 }
477 else if (udp_hdr->check == 0)
478 fl_csum = 1;
479 }
480
481 /* Copy UDP data to new IPv6 packet */
482 udp_hdr = (struct udphdr *)(dst+sizeof(struct ipv6hdr)
483 + fr_flag*sizeof(struct frag_hdr));
484 memcpy((char *)udp_hdr, src+hdr_len, len - hdr_len);
485
486 /* Calculate UDP checksum if UDP checksum in IPv4 packet was ZERO
487 and if it isn't included IP packet
488 */
489 if (fl_csum && (!include_flag)) {
490 udp_hdr->check = 0;
491 csum = 0;
492 csum = csum_partial((unsigned char *)udp_hdr, plen - fr_flag*sizeof(struct frag_hdr), csum);
493 udp_hdr->check = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, plen -
494 fr_flag*sizeof(struct frag_hdr), IPPROTO_UDP, csum);
495 }
496 break;
497
498 /* Discard packets with any other protocol */
499 default:
500 PDEBUG("ip4_ip6(): Unknown upper protocol - packet dropped.\n");
501 return -1;
502 }
503
504 #ifdef SIIT_DEBUG
505 siit_print_dump(dst, sizeof(struct ipv6hdr), "siit: ip4_ip6(): (out) ipv6 header dump");
506 #endif
507
508 return 0;
509 }
510
511 /*
512 * Translation IPv6 to IPv4 stuff
513 *
514 * ip6_ip4(src, len, dst, include_flag)
515 *
516 * where
517 * src - buffer with original IPv6 packet,
518 * len - size of original packet,
519 * dst - new buffer for IPv4 packet,
520 * include_flag - if = 1, dst point to IPv6 packet that is ICMP error
521 * included IP packet, else = 0
522 *
523 */
524
525 static int ip6_ip4(char *src, int len, char *dst, int include_flag)
526 {
527 struct ipv6hdr *ip6_hdr; /* point to current IPv6 header struct */
528 struct iphdr *ip_hdr; /* point to current IPv4 header struct */
529 int opts_len = 0; /* to sum Option Headers length */
530 int icmperr = 1; /* if = 1, indicate that packet is ICMP Error message, else = 0 */
531 int ntot_len = 0; /* to calculate IPv6 Total Length field */
532 int real_len;
533 int len_delta;
534 int ip6_payload_len;
535 int inc_opts_len = 0; /* to sum Option Headers length in ICMP included IP packet */
536 __u8 next_hdr; /* Next Header */
537
538 #ifdef SIIT_DEBUG
539 siit_print_dump(src, sizeof(struct ipv6hdr), "siit: ip6_ip4(): (in) ipv6 header dump");
540 #endif
541
542 if ( (len_delta = len - sizeof(struct ipv6hdr)) >= 0)
543 {
544 ip6_hdr = (struct ipv6hdr *)src;
545 ip_hdr = (struct iphdr *)dst;
546
547 real_len = sizeof(struct iphdr);
548
549 /* Check validation of Saddr & Daddr? is a packet to fall under our translation? */
550 if (include_flag) { /* It's ICMP included IP packet,
551 about process include_flag see comment in ip4_ip6() */
552 if (ip6_hdr->saddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
553 PDEBUG("ip6_ip4(): Included IP packet Src addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
554 ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
555 ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
556 return -1;
557 }
558 if ( ip6_hdr->daddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
559 PDEBUG("ip6_ip4(): Included IP packet Dst addr isn't translated addr: %x%x%x%x, packet dropped.\n",
560 ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
561 ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
562 return -1;
563 }
564 }
565 else { /* It's normal IP packet (not included in ICMP) */
566 if (ip6_hdr->saddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
567 PDEBUG("ip6_ip4(): Src addr isn't translated addr: %x%x%x%x, packet dropped.\n",
568 ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
569 ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
570 return -1;
571 }
572 if ( ip6_hdr->daddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
573 PDEBUG("ip6_ip4(): Dst addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
574 ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
575 ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
576 return -1;
577 }
578 }
579
580 /* Set IPv4 Fragment Offset and ID to 0
581 before process any Option Headers */
582 ip_hdr->frag_off = 0;
583 ip_hdr->id = 0;
584
585 /*
586 * We process only Fragment Header. Any other options headers
587 * are ignored, i.e. there is no attempt to translate them.
588 * However, the Total Length field and the Protocol field would
589 * have to be adjusted to "skip" these extension headers.
590 */
591
592 next_hdr = ip6_hdr->nexthdr;
593
594 /* Hop_by_Hop options header (ip6_hdr->nexthdr = 0). It must
595 * appear only in IPv6 header's Next Header field.
596 */
597 if (next_hdr == NEXTHDR_HOP) {
598 if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
599 {
600 struct ipv6_opt_hdr *ip6h =
601 (struct ipv6_opt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
602 if ( (len_delta -= ip6h->hdrlen*8 + 8) >= 0)
603 {
604 opts_len += ip6h->hdrlen*8 + 8; /* See RFC 2460 page 11:
605 Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by-
606 Hop Options header in 8-octet units, not
607 including the first 8 octets.
608 */
609 next_hdr = ip6h->nexthdr;
610 }
611 else
612 {
613 PDEBUG("ip6_ip4(): hop_by_hop header error, packet droped");
614 /* Generate ICMP Parameter Problem */
615 return -1;
616 }
617 }
618 }
619
620 if (len_delta > 0)
621 {
622 while(next_hdr != NEXTHDR_ICMP && next_hdr != NEXTHDR_TCP
623 && next_hdr != NEXTHDR_UDP)
624 {
625 /* Destination options header */
626 if (next_hdr == NEXTHDR_DEST)
627 {
628 if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
629 {
630 struct ipv6_opt_hdr *ip6d =
631 (struct ipv6_opt_hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
632 if ( (len_delta -= ip6d->hdrlen*8 + 8) >= 0)
633 {
634 opts_len += ip6d->hdrlen*8 + 8;
635 next_hdr = ip6d->nexthdr;
636 }
637 }
638 else
639 {
640 PDEBUG("ip6_ip4(): destination header error, packet droped");
641 /* Generate ICMP Parameter Problem */
642 return -1;
643 }
644 }
645 /* Routing options header */
646 else if (next_hdr == NEXTHDR_ROUTING)
647 {
648 if ( (len_delta - sizeof(struct ipv6_rt_hdr)) >= 0)
649 {
650 struct ipv6_rt_hdr *ip6rt =
651 (struct ipv6_rt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
652 /* RFC 2765 SIIT, 4.1:
653 If a routing header with a non-zero Segments Left field is present
654 then the packet MUST NOT be translated, and an ICMPv6 "parameter
655 problem/ erroneous header field encountered" (Type 4/Code 0) error
656 message, with the Pointer field indicating the first byte of the
657 Segments Left field, SHOULD be returned to the sender.
658 */
659 if (ip6rt->segments_left != 0) {
660 /* Build ICMPv6 "Parameter Problem/Erroneous Header
661 Field Encountered" & drop the packet */
662 /* !!! We don't send ICMPv6 "Parameter Problem" !!! */
663 PDEBUG("ip6_ip4(): routing header type != 0\n");
664 return -1;
665 }
666 if ( (len_delta -= ip6rt->hdrlen*8 + 8) >= 0)
667 {
668 opts_len += ip6rt->hdrlen*8 + 8;
669 next_hdr = ip6rt->nexthdr;
670 }
671 else
672 {
673 PDEBUG("ip6_ip4(): routing header error, packet droped");
674 /* Generate ICMP Parameter Problem */
675 return -1;
676 }
677 }
678 }
679 /* Fragment options header */
680 else if (next_hdr == NEXTHDR_FRAGMENT)
681 {
682 if ( (len_delta -= sizeof(struct frag_hdr)) >= 0)
683 {
684 struct frag_hdr *ip6f =
685 (struct frag_hdr *)(src+sizeof(struct ipv6hdr)+opts_len);
686
687 opts_len += sizeof(struct frag_hdr); /* Frag Header Length = 8 */
688 ip_hdr->id = htons(ntohl(ip6f->identification)); /* ID field */
689 ip_hdr->frag_off = htons((ntohs(ip6f->frag_off) & IP6F_OFF_MASK) >> 3);
690 /* fragment offset */
691 ip_hdr->frag_off = htons(ntohs(ip_hdr->frag_off) |
692 ((ntohs(ip6f->frag_off) & IP6F_MORE_FRAG) << 13));
693 /* more fragments flag */
694 next_hdr = ip6f->nexthdr;
695 }
696 else
697 {
698 PDEBUG("ip6_ip4(): fragment header error, packet droped");
699 /* Generate ICMP Parameter Problem */
700 return -1;
701 }
702 }
703 /* No Next Header */
704 else if (next_hdr == NEXTHDR_NONE)
705 {
706 /* RFC 2460 IPv6 Specification, 4.7
707 4.7 No Next Header
708
709 The value 59 in the Next Header field of an IPv6 header or any
710 extension header indicates that there is nothing following that
711 header. If the Payload Length field of the IPv6 header indicates the
712 presence of octets past the end of a header whose Next Header field
713 contains 59, those octets must be ignored, and passed on unchanged if
714 the packet is forwarded.
715 */
716 break;
717 }
718 else if (next_hdr == NEXTHDR_ESP || next_hdr == NEXTHDR_AUTH)
719 {
720 PDEBUG("ip6_ip4(): cannot translate AUTH or ESP extention header, packet dropped\n");
721 return -1;
722 }
723 else if (next_hdr == NEXTHDR_IPV6)
724 {
725 PDEBUG("ip6_ip4(): cannot translate IPv6-IPv6 packet, packet dropped\n");
726 return -1;
727 }
728 else if (next_hdr == 0)
729 {
730 /* As say RFC 2460 (IPv6 Spec) we should discard the packet and send an
731 ICMP Parameter Problem message to the source of the packet, with an
732 ICMP Code value of 1 ("unrecognized Next Header type encountered")
733 and the ICMP Pointer field containing the offset of the unrecognized
734 value within the original packet
735 */
736 /* NOT IMPLEMENTED */
737 PDEBUG("ip6_ip4(): NEXTHDR in extention header = 0, packet dropped\n");
738 return -1;
739 }
740 else
741 {
742 PDEBUG("ip6_ip4(): cannot translate extention header = %d, packet dropped\n", next_hdr);
743 return -1;
744 }
745 }
746 }
747 }
748 else
749 {
750 PDEBUG("ip6_ip4(): error packet len, packet dropped.\n");
751 return -1;
752 }
753
754 /* Building ipv4 packet */
755
756 ip_hdr->version = IPVERSION;
757 ip_hdr->ihl = 5;
758
759 /* TOS see comment about TOS in ip4_ip6() */
760 if (tos_ignore_flag)
761 ip_hdr->tos = 0;
762 else {
763 ip_hdr->tos = ip6_hdr->priority << 4;
764 ip_hdr->tos = ip_hdr->tos | (ip6_hdr->flow_lbl[0] >> 4);
765 }
766
767 /* IPv4 Total Len = IPv6 Payload Len +
768 IPv4 Header Len (without options) - Options Headers Len */
769 ip6_payload_len = ntohs(ip6_hdr->payload_len);
770
771 if (ip6_payload_len == 0)
772 ntot_len = 0;
773 else
774 ntot_len = ip6_payload_len + IP4_IP6_HDR_DIFF - opts_len;
775
776 ip_hdr->tot_len = htons(ntot_len);
777
778 /* IPv4 TTL = IPv6 Hop Limit */
779 ip_hdr->ttl = ip6_hdr->hop_limit;
780
781 /* IPv4 Protocol = Next Header that will point to upper layer protocol */
782 ip_hdr->protocol = next_hdr;
783
784 /* IPv4 Src addr = last 4 bytes from IPv6 Src addr */
785 ip_hdr->saddr = ip6_hdr->saddr.s6_addr32[3];
786 /* IPv4 Dst addr = last 4 bytes from IPv6 Dst addr */
787 ip_hdr->daddr = ip6_hdr->daddr.s6_addr32[3];
788
789 /* Calculate IPv4 header checksum */
790 ip_hdr->check = 0;
791 ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
792
793 if (len_delta > 0)
794 {
795 /* PROCESS ICMP */
796
797 if (next_hdr == NEXTHDR_ICMP)
798 {
799 struct icmp6hdr *icmp6_hdr;
800 struct icmphdr *icmp_hdr;
801
802 if ((len_delta -= sizeof(struct icmp6hdr)) >= 0)
803 {
804 icmp6_hdr = (struct icmp6hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
805 icmp_hdr = (struct icmphdr *)(dst + sizeof(struct iphdr));
806
807 real_len += len_delta + sizeof(struct icmphdr);
808
809 /* There is diffirent between ICMPv4/ICMPv6 protocol codes
810 IPPROTO_ICMP = 1
811 IPPROTO_ICMPV6 = 58 */
812 ip_hdr->protocol = IPPROTO_ICMP;
813
814 if (include_flag) {
815 /* !!! Warnig !!! We discard ICMP packets with any ICMP as included
816 in ICMP Error. But ICMP Error messages can include ICMP Query message
817 */
818 if (icmp6_hdr->icmp6_type != ICMPV6_ECHO_REQUEST)
819 {
820 PDEBUG("ip6_ip4(): included ICMPv6 in ICMPv6 Error message, packet dropped\n");
821 return -1;
822 }
823 }
824
825 /* Translate ICMPv6 to ICMPv4 */
826 switch (icmp6_hdr->icmp6_type)
827 {
828 /* ICMP Error messages */
829 /* Destination Unreachable (Type 1) */
830 case ICMPV6_DEST_UNREACH: /* Type 1 */
831 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
832 icmp_hdr->un.echo.id = 0;
833 icmp_hdr->un.echo.sequence = 0;
834 switch (icmp6_hdr->icmp6_code)
835 {
836 case ICMPV6_NOROUTE: /* Code 0 */
837 case ICMPV6_NOT_NEIGHBOUR: /* Code 2 */
838 case ICMPV6_ADDR_UNREACH: /* Code 3 */
839 icmp_hdr->code = ICMP_HOST_UNREACH; /* To Code 1 */
840 break;
841 case ICMPV6_ADM_PROHIBITED: /* Code 1 */
842 icmp_hdr->code = ICMP_HOST_ANO; /* To Code 10 */
843 break;
844 case ICMPV6_PORT_UNREACH: /* Code 4 */
845 icmp_hdr->code = ICMP_PORT_UNREACH; /* To Code 3 */
846
847 break;
848 default: /* discard any other codes */
849 PDEBUG("ip6_ip4(): Unknown ICMPv6 Type %d Code %d - packet dropped.\n",
850 ICMPV6_DEST_UNREACH, icmp6_hdr->icmp6_code);
851 return -1;
852 }
853 break;
854 /* Packet Too Big (Type 2) */
855 case ICMPV6_PKT_TOOBIG: /* Type 2 */
856 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
857 icmp_hdr->code = ICMP_FRAG_NEEDED; /* to Code 4 */
858 /* Change MTU, RFC 2765 (SIIT), 4.2:
859 The MTU field needs to be adjusted for the difference between
860 the IPv4 and IPv6 header sizes taking into account whether or
861 not the packet in error includes a Fragment header.
862 */
863 /* !!! Don't implement !!! */
864 icmp_hdr->un.frag.mtu = (__u16) icmp6_hdr->icmp6_mtu;
865 break;
866 /* Time Exceeded (Type 3) */
867 case ICMPV6_TIME_EXCEED:
868 icmp_hdr->type = ICMP_TIME_EXCEEDED; /* to Type 11 */
869 icmp_hdr->code = icmp6_hdr->icmp6_code; /* Code unchanged */
870 break;
871 /* Parameter Problem (Type 4) */
872 case ICMPV6_PARAMPROB:
873 switch (icmp6_hdr->icmp6_code) {
874 case ICMPV6_UNK_NEXTHDR: /* Code 1 */
875 icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
876 icmp_hdr->code = ICMP_PROT_UNREACH; /* to Code 2 */
877 break;
878 default: /* if Code != 1 */
879 icmp_hdr->type = ICMP_PARAMETERPROB; /* to Type 12 */
880 icmp_hdr->code = 0; /* to Code 0 */
881 /* Update Pointer field
882 RFC 2765 (SIIT), 4.2:
883 The Pointer needs to be updated to point to the corresponding
884 field in the translated include IP header.
885 */
886 switch (ntohl(icmp6_hdr->icmp6_pointer))
887 {
888 case 0: /* IPv6 Version -> IPv4 Version */
889 icmp_hdr->un.echo.id = 0;
890 break;
891 case 4: /* IPv6 PayloadLength -> IPv4 Total Length */
892 icmp_hdr->un.echo.id = 0x0002; /* 2 */
893 break;
894 case 6: /* IPv6 Next Header-> IPv4 Protocol */
895 icmp_hdr->un.echo.id = 0x0009; /* 9 */
896 break;
897 case 7: /* IPv6 Hop Limit -> IPv4 TTL */
898 icmp_hdr->un.echo.id = 0x0008; /* 8 */
899 break;
900 case 8: /* IPv6 Src addr -> IPv4 Src addr */
901 icmp_hdr->un.echo.id = 0x000c; /* 12 */
902 break;
903 case 24: /* IPv6 Dst addr -> IPv4 Dst addr*/
904 icmp_hdr->un.echo.id = 0x0010; /* 16 */
905 break;
906 default: /* set all ones in other cases */
907 icmp_hdr->un.echo.id = 0xff;
908 break;
909 }
910 break;
911 }
912 break;
913
914 /* End of ICMP Error messages */
915
916 /* Echo Request and Echo Reply (Type 128 and 129) */
917 case ICMPV6_ECHO_REQUEST:
918 icmperr = 0; /* not error ICMP message */
919 icmp_hdr->type = ICMP_ECHO; /* to Type 8 */
920 icmp_hdr->code = 0; /* to Code 0 */
921 icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
922 icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
923 /* copy rest of ICMP data to result packet */
924 if (len_delta > 0)
925 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
926 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
927 break;
928 case ICMPV6_ECHO_REPLY:
929 icmperr = 0; /* not error ICMP message */
930 icmp_hdr->type = ICMP_ECHOREPLY; /* to Type 0 */
931 icmp_hdr->code = 0; /* to Code 0 */
932 icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
933 icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
934 /* copy rest of ICMP data */
935 if (len_delta > 0)
936 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
937 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
938 break;
939 default:
940 /* Unknown error messages. Silently drop. */
941 PDEBUG("ip6_ip4(): unknown ICMPv6 Type %d, packet dropped.\n", icmp6_hdr->icmp6_type);
942 return -1;
943 }
944
945 if (icmperr)
946 {
947 /* If ICMP Error message, we translate IP included packet*/
948 if (len_delta >= sizeof(struct ipv6hdr))
949 {
950 if((inc_opts_len = ip6_ip4((char *)icmp6_hdr + sizeof(struct icmp6hdr), len_delta,
951 (char *)icmp_hdr + sizeof(struct icmphdr), 1)) == -1) {
952 PDEBUG("ip6_ip4(): incorrect translation of ICMPv6 Error message, packet dropped\n");
953 return -1;
954 }
955 /* correct IPv4 Total Len that = old Total Len
956 - Options Headers Len in included IP packet
957 - diffirence between IPv6 Header Len and IPv4 Header Len
958 */
959 if (ntot_len != 0)
960 ip_hdr->tot_len = htons(ntot_len - inc_opts_len - IP4_IP6_HDR_DIFF);
961 real_len = real_len - inc_opts_len - IP4_IP6_HDR_DIFF;
962 }
963 else if (len_delta > 0)
964 {
965 /* May be it need set 0x0 to rest area in result IPv4 packet,
966 * but we copy rest data unchanged
967 */
968 memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
969 ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
970 }
971 }
972
973 /* Calculate IPv4 Header checksum */
974 ip_hdr->check = 0;
975 ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
976
977 /* Calculate ICMPv4 checksum */
978 if (ntot_len != 0)
979 {
980 icmp_hdr->checksum = 0;
981 icmp_hdr->checksum = ip_compute_csum((unsigned char *)icmp_hdr, ntohs(ip_hdr->tot_len)
982 - sizeof(struct iphdr));
983 }
984 }
985 else
986 {
987 PDEBUG("ip6_ip4(): error length ICMP packet, packet dropped.\n");
988 return -1;
989 }
990
991 }
992 /* PROCESS TCP and UDP (and rest data) */
993
994 else {
995 real_len += len_delta;
996 /* we copy rest data to IPv4 packet without changing */
997 memcpy(dst+sizeof(struct iphdr), src + sizeof(struct ipv6hdr) + opts_len, len_delta);
998 }
999 }
1000
1001 if (include_flag) /* if it's included IP packet */
1002 return opts_len; /* return options headers length */
1003 else
1004 return real_len; /* result packet len */
1005 }
1006
1007 /*
1008 * ip4_fragment(skb, len, hdr_len, dev, eth_h)
1009 * to fragment original IPv4 packet if result IPv6 packet will be > 1280
1010 */
1011
1012 static int ip4_fragment(struct sk_buff *skb, int len, int hdr_len, struct net_device *dev, struct ethhdr *eth_h)
1013 {
1014 struct sk_buff *skb2 = NULL; /* pointer to new struct sk_buff for transleded packet */
1015 char buff[FRAG_BUFF_SIZE+hdr_len]; /* buffer to form new fragment packet */
1016 char *cur_ptr = skb->data+hdr_len; /* pointter to current packet data with len = frag_len */
1017 struct iphdr *ih4 = (struct iphdr *) skb->data;
1018 struct iphdr *new_ih4 = (struct iphdr *) buff; /* point to new IPv4 hdr */
1019 struct ethhdr *new_eth_h; /* point to ether hdr, need to set hard header data in fragment */
1020 int data_len = len - hdr_len; /* origin packet data len */
1021 int rest_len = data_len; /* rest data to fragment */
1022 int frag_len = 0; /* current fragment len */
1023 int last_frag = 0; /* last fragment flag, if = 1, it's last fragment */
1024 int flag_last_mf = 0;
1025 __u16 new_id = 0; /* to generate identification field */
1026 __u16 frag_offset = 0; /* fragment offset */
1027 unsigned int csum;
1028 unsigned short udp_len;
1029
1030 #ifdef SIIT_DEBUG
1031 printk("siit: it's DF == 0 and result IPv6 packet will be > 1280\n");
1032 siit_print_dump(skb->data, hdr_len, "siit: (orig) ipv4_hdr dump");
1033 #endif
1034
1035 if ((ntohs(ih4->frag_off) & IP_MF) == 0 )
1036 /* it's a case we'll clear MF flag in our last packet */
1037 flag_last_mf = 1;
1038
1039 if (ih4->protocol == IPPROTO_UDP) {
1040 if ( (ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
1041 struct udphdr *udp_hdr = (struct udphdr *)((char *)ih4 + hdr_len);
1042 if (!flag_last_mf) {
1043 if (udp_hdr->check == 0) {
1044 /* it's a first fragment with ZERO checksum and we drop packet */
1045 printk("siit: First fragment of UDP with zero checksum - packet droped\n");
1046 printk("siit: addr: %x src port: %d dst port: %d\n",
1047 htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
1048 return -1;
1049 }
1050 }
1051 else if (udp_hdr->check == 0) {
1052 /* Calculate UDP checksum only if it's not fragment */
1053 udp_len = ntohs(udp_hdr->len);
1054 csum = 0;
1055 csum = csum_partial((unsigned char *)udp_hdr, udp_len, csum);
1056 udp_hdr->check = csum_tcpudp_magic(ih4->saddr, ih4->daddr, udp_len, IPPROTO_UDP, csum);
1057 }
1058 }
1059 }
1060
1061 frag_offset = ntohs(ih4->frag_off) & IP_OFFSET;
1062
1063 new_id = ih4->id;
1064
1065 while(1) {
1066 if (rest_len <= FRAG_BUFF_SIZE) {
1067 /* it's last fragmen */
1068 frag_len = rest_len; /* rest data */
1069 last_frag = 1;
1070 }
1071 else
1072 frag_len = FRAG_BUFF_SIZE;
1073
1074 /* copy IP header to buffer */
1075 memcpy(buff, skb->data, hdr_len);
1076 /* copy data to buffer with len = frag_len */
1077 memcpy(buff + hdr_len, cur_ptr, frag_len);
1078
1079 /* set id field in new IPv4 header*/
1080 new_ih4->id = new_id;
1081
1082 /* is it last fragmet */
1083 if(last_frag && flag_last_mf)
1084 /* clear MF flag */
1085 new_ih4->frag_off = htons(frag_offset & (~IP_MF));
1086 else
1087 /* set MF flag */
1088 new_ih4->frag_off = htons(frag_offset | IP_MF);
1089
1090 /* change packet total length */
1091 new_ih4->tot_len = htons(frag_len+hdr_len);
1092
1093 /* rebuild the header checksum (IP needs it) */
1094 new_ih4->check = 0;
1095 new_ih4->check = ip_fast_csum((unsigned char *)new_ih4,new_ih4->ihl);
1096
1097 /* Allocate new sk_buff to compose translated packet */
1098 skb2 = dev_alloc_skb(frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE);
1099 if (!skb2) {
1100 printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1101 dev_kfree_skb(skb2);
1102 return -1;
1103 }
1104 /* allocate skb->data portion for IP header len, fragment data len and ether header len
1105 * and copy to head ether header from origin skb
1106 */
1107 memcpy(skb_put(skb2, frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE), (char *) eth_h,
1108 dev->hard_header_len);
1109 /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1110 new_eth_h = (struct ethhdr *)skb2->data;
1111 new_eth_h->h_proto = htons(ETH_P_IPV6);
1112
1113 /* reset the mac header */
1114 skb_reset_mac_header(skb2);
1115
1116 /* pull ether header from new skb->data */
1117 skb_pull(skb2, dev->hard_header_len);
1118 /* set skb protocol to IPV6 */
1119 skb2->protocol = htons(ETH_P_IPV6);
1120
1121 /* call translation function */
1122 if ( ip4_ip6(buff, frag_len+hdr_len, skb2->data, 0) == -1) {
1123 dev_kfree_skb(skb2);
1124 return -1;
1125 }
1126
1127 /*
1128 * Set needed fields in new sk_buff
1129 */
1130 skb2->dev = dev;
1131 skb2->ip_summed = CHECKSUM_UNNECESSARY;
1132 skb2->pkt_type = PACKET_HOST;
1133
1134 /* Add transmit statistic */
1135 siit_stats(dev)->tx_packets++;
1136 siit_stats(dev)->tx_bytes += skb2->len;
1137
1138 /* send packet to upper layer */
1139 netif_rx(skb2);
1140
1141 /* exit if it was last fragment */
1142 if (last_frag)
1143 break;
1144
1145 /* correct current data pointer */
1146 cur_ptr += frag_len;
1147 /* rest data len */
1148 rest_len -= frag_len;
1149 /* current fragment offset */
1150 frag_offset = (frag_offset*8 + frag_len)/8;
1151 }
1152
1153 return 0;
1154 }
1155 /*
1156 * Transmit a packet (called by the kernel)
1157 *
1158 * siit_xmit(skb, dev)
1159 *
1160 * where
1161 * skb - pointer to struct sk_buff with incomed packet
1162 * dev - pointer to struct device on which packet revieved
1163 *
1164 * Statistic:
1165 * for all incoming packes:
1166 * stats.rx_bytes+=skb->len
1167 * stats.rx_packets++
1168 * for packets we can't transle:
1169 * stats.tx_errors++
1170 * device busy:
1171 * stats.tx_errors++
1172 * for packets we can't allocate sk_buff:
1173 * stats.tx_dropped++
1174 * for outgoing packes:
1175 * stats.tx_packets++
1176 * stats.tx_bytes+=skb2->len !!! But we don't set skb2->len !!!
1177 */
1178
1179 static int siit_xmit(struct sk_buff *skb, struct net_device *dev)
1180 {
1181 struct sk_buff *skb2 = NULL;/* pointer to new struct sk_buff for transleded packet */
1182 struct ethhdr *eth_h; /* pointer to incoming Ether header */
1183 int len; /* original packets length */
1184 int new_packet_len;
1185 int skb_delta = 0; /* delta size for allocate new skb */
1186 char new_packet_buff[2048];
1187
1188 /* Check pointer to sk_buff and device structs */
1189 if (skb == NULL || dev == NULL)
1190 return -EINVAL;
1191
1192 /* Add receive statistic */
1193 siit_stats(dev)->rx_bytes += skb->len;
1194 siit_stats(dev)->rx_packets++;
1195
1196 dev->trans_start = jiffies;
1197
1198 /* Upper layer (IP) protocol forms sk_buff for outgoing packet
1199 * and sets IP header + Ether header too. IP layer sets outgoing
1200 * device in sk_buff->dev.
1201 * In function (from linux/net/core/dev.c) ther is a call to
1202 * device transmit function (dev->hard_start_xmit):
1203 *
1204 * dev_queue_xmit(struct sk_buff *skb)
1205 * {
1206 * ...
1207 * device *dev = skb->dev;
1208 * ...
1209 * dev->hard_start_xmit(skb, dev);
1210 * ...
1211 * }
1212 * We save pointer to ether header in eth_h and skb_pull ether header
1213 * from data field of skb_buff
1214 */
1215
1216 eth_h = (struct ethhdr *)skb->data; /* point to incoming packet Ether Header */
1217
1218 #ifdef SIIT_DEBUG
1219 siit_print_dump(skb->data, ETH_HLEN, "siit: eth_hdr dump");
1220 #endif
1221
1222 /* Remove hardware header from origin sk_buff */
1223 skb_pull(skb,dev->hard_header_len);
1224
1225 /*
1226 * Process IPv4 paket
1227 */
1228 if (ntohs(skb->protocol) == ETH_P_IP) {
1229 int hdr_len; /* IPv4 header length */
1230 int data_len; /* IPv4 data length */
1231 struct iphdr *ih4; /* pointer to IPv4 header */
1232 struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
1233
1234 ih4 = (struct iphdr *)skb->data; /* point to incoming packet's IPv4 header */
1235
1236 /* Check IPv4 Total Length */
1237 if (skb->len != ntohs(ih4->tot_len)) {
1238 PDEBUG("siit_xmit(): Different skb_len %x and ip4 tot_len %x - packet dropped.\n",
1239 skb->len, ih4->tot_len);
1240 siit_stats(dev)->tx_errors++;
1241 dev_kfree_skb(skb);
1242 return 0;
1243 }
1244
1245 len = skb->len; /* packet's total len */
1246 hdr_len = (int)(ih4->ihl * 4); /* packet's header len */
1247 data_len = len - hdr_len; /* packet's data len */
1248
1249 /* If DF == 0 */
1250 if ( (ntohs(ih4->frag_off) & IP_DF) == 0 ) {
1251 /* If result IPv6 packet will be > 1280
1252 we need to fragment original IPv4 packet
1253 */
1254 if ( data_len > FRAG_BUFF_SIZE ) {
1255 /* call function that fragment packet and translate to IPv6 each fragment
1256 * and send to upper layer
1257 */
1258 if ( ip4_fragment(skb, len, hdr_len, dev, eth_h) == -1) {
1259 siit_stats(dev)->tx_errors++;
1260 }
1261 /* Free incoming skb */
1262 dev_kfree_skb(skb);
1263 /* Device can accept a new packet */
1264
1265 return 0;
1266
1267 }
1268 }
1269 /* If DF == 1 && MF == 0 && Fragment Offset == 0
1270 * we don't include fragment header
1271 */
1272 if ( ntohs(ih4->frag_off) == IP_DF )
1273 skb_delta = IP4_IP6_HDR_DIFF; /* delta is +20 */
1274 else
1275 skb_delta = IP4_IP6_HDR_DIFF + IP6_FRAGMENT_SIZE; /* delta is +20 and +8 */
1276
1277 /* If it's ICMP, check is it included IP packet in it */
1278 if ( ih4->protocol == IPPROTO_ICMP) {
1279 icmp_hdr = (struct icmphdr *) (skb->data+hdr_len); /* point to ICMPv4 header */
1280 if ( icmp_hdr->type != ICMP_ECHO && icmp_hdr->type != ICMP_ECHOREPLY) {
1281 /*
1282 * It's ICMP Error that has included IP packet
1283 * we'll add only +20 because we don't include Fragment Header
1284 * into translated included IP packet
1285 */
1286 skb_delta += IP4_IP6_HDR_DIFF;
1287 }
1288 }
1289
1290 /* Allocate new sk_buff to compose translated packet */
1291 skb2 = dev_alloc_skb(len+dev->hard_header_len+skb_delta);
1292 if (!skb2) {
1293 printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1294 dev_kfree_skb(skb);
1295 siit_stats(dev)->rx_dropped++;
1296
1297 return 0;
1298 }
1299 /* allocate skb->data portion = IPv4 packet len + ether header len
1300 * + skb_delta (max = two times (diffirence between IPv4 header and
1301 * IPv6 header + Frag Header), second for included packet,
1302 * and copy to head of skb->data ether header from origin skb
1303 */
1304 memcpy(skb_put(skb2, len+dev->hard_header_len+skb_delta), (char *)eth_h, dev->hard_header_len);
1305 /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1306 eth_h = (struct ethhdr *)skb2->data;
1307 eth_h->h_proto = htons(ETH_P_IPV6);
1308 skb_reset_mac_header(skb2);
1309 /* remove ether header from new skb->data,
1310 * NOTE! data will rest, pointer to data and data len will change
1311 */
1312 skb_pull(skb2,dev->hard_header_len);
1313 /* set skb protocol to IPV6 */
1314 skb2->protocol = htons(ETH_P_IPV6);
1315
1316 /* call translation function */
1317 if (ip4_ip6(skb->data, len, skb2->data, 0) == -1 ) {
1318 dev_kfree_skb(skb);
1319 dev_kfree_skb(skb2);
1320 siit_stats(dev)->rx_errors++;
1321
1322 return 0;
1323 }
1324 }
1325 /*
1326 * IPv6 paket
1327 */
1328 else if (ntohs(skb->protocol) == ETH_P_IPV6) {
1329
1330 #ifdef SIIT_DEBUG
1331 siit_print_dump(skb->data, sizeof(struct ipv6hdr), "siit: (in) ip6_hdr dump");
1332 #endif
1333 /* packet len = skb->data len*/
1334 len = skb->len;
1335
1336 /* call translation function */
1337 if ((new_packet_len = ip6_ip4(skb->data, len, new_packet_buff, 0)) == -1 )
1338 {
1339 PDEBUG("siit_xmit(): error translation ipv6->ipv4, packet dropped.\n");
1340 siit_stats(dev)->rx_dropped++;
1341 goto end;
1342 }
1343
1344 /* Allocate new sk_buff to compose translated packet */
1345 skb2 = dev_alloc_skb(new_packet_len + dev->hard_header_len);
1346 if (!skb2) {
1347 printk(KERN_DEBUG "%s: alloc_skb failure, packet dropped.\n", dev->name);
1348 siit_stats(dev)->rx_dropped++;
1349 goto end;
1350 }
1351 memcpy(skb_put(skb2, new_packet_len + dev->hard_header_len), (char *)eth_h, dev->hard_header_len);
1352 eth_h = (struct ethhdr *)skb2->data;
1353 eth_h->h_proto = htons(ETH_P_IP);
1354 skb_reset_mac_header(skb2);
1355 skb_pull(skb2, dev->hard_header_len);
1356 memcpy(skb2->data, new_packet_buff, new_packet_len);
1357 skb2->protocol = htons(ETH_P_IP);
1358 }
1359 else {
1360 PDEBUG("siit_xmit(): unsupported protocol family %x, packet dropped.\n", skb->protocol);
1361 goto end;
1362 }
1363
1364 /*
1365 * Set needed fields in new sk_buff
1366 */
1367 skb2->pkt_type = PACKET_HOST;
1368 skb2->dev = dev;
1369 skb2->ip_summed = CHECKSUM_UNNECESSARY;
1370
1371 /* Add transmit statistic */
1372 siit_stats(dev)->tx_packets++;
1373 siit_stats(dev)->tx_bytes += skb2->len;
1374
1375 /* Send packet to upper layer protocol */
1376 netif_rx(skb2);
1377
1378 end:
1379 dev_kfree_skb(skb);
1380
1381 return 0;
1382 }
1383
1384 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0)
1385 static bool header_ops_init = false;
1386 static struct header_ops siit_header_ops ____cacheline_aligned;
1387 #endif
1388
1389 #if !(defined CONFIG_COMPAT_NET_DEV_OPS) && LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
1390 static const struct net_device_ops siit_netdev_ops = {
1391 .ndo_open = siit_open,
1392 .ndo_stop = siit_release,
1393 .ndo_start_xmit = siit_xmit,
1394 };
1395 #endif
1396
1397 /*
1398 * The init function initialize of the SIIT device..
1399 * It is invoked by register_netdev()
1400 */
1401
1402 static void
1403 siit_init(struct net_device *dev)
1404 {
1405 ether_setup(dev); /* assign some of the fields */
1406 random_ether_addr(dev->dev_addr);
1407
1408 /*
1409 * Assign device function.
1410 */
1411 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,30)
1412 dev->open = siit_open;
1413 dev->stop = siit_release;
1414 dev->hard_start_xmit = siit_xmit;
1415 #else
1416 #if !(defined CONFIG_COMPAT_NET_DEV_OPS) && LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
1417 dev->netdev_ops = &siit_netdev_ops;
1418 #endif
1419 #endif
1420 dev->flags |= IFF_NOARP; /* ARP not used */
1421 dev->tx_queue_len = 10;
1422
1423 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
1424 dev->hard_header_cache = NULL; /* Disable caching */
1425 memset(netdev_priv(dev), 0, sizeof(struct net_device_stats));
1426 dev->get_stats = siit_get_stats;
1427 #else
1428 if (!header_ops_init) {
1429 memcpy(&siit_header_ops, dev->header_ops, sizeof(struct header_ops));
1430 siit_header_ops.cache = NULL;
1431 }
1432 dev->header_ops = &siit_header_ops;
1433 #endif
1434 }
1435
1436 /*
1437 * Finally, the module stuff
1438 */
1439 static struct net_device *siit_dev = NULL;
1440
1441 int init_module(void)
1442 {
1443 int res = -ENOMEM;
1444 int priv_size;
1445
1446 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
1447 priv_size = sizeof(struct net_device_stats);
1448 #else
1449 priv_size = sizeof(struct header_ops);
1450 #endif
1451 siit_dev = alloc_netdev(priv_size, "siit%d", siit_init);
1452 if (!siit_dev)
1453 goto err_alloc;
1454
1455 res = register_netdev(siit_dev);
1456 if (res)
1457 goto err_register;
1458
1459 return 0;
1460
1461 err_register:
1462 free_netdev(siit_dev);
1463 err_alloc:
1464 printk(KERN_ERR "Error creating siit device: %d\n", res);
1465 return res;
1466 }
1467
1468 void cleanup_module(void)
1469 {
1470 unregister_netdev(siit_dev);
1471 free_netdev(siit_dev);
1472 }
1473
1474
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