Root/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/version.h>
8#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33))
9#include <generated/autoconf.h>
10#else
11#include <linux/autoconf.h>
12#endif
13#include <linux/module.h>
14#include <linux/sched.h>
15#include <linux/kernel.h> /* printk() */
16#include <linux/slab.h>
17
18#include <linux/errno.h> /* error codes */
19#include <linux/types.h> /* size_t */
20#include <linux/interrupt.h> /* mark_bh */
21#include <linux/random.h>
22#include <linux/in.h>
23#include <linux/netdevice.h> /* struct device, and other headers */
24#include <linux/etherdevice.h> /* eth_type_trans */
25#include <net/ip.h> /* struct iphdr */
26#include <net/icmp.h> /* struct icmphdr */
27#include <net/ipv6.h>
28#include <net/udp.h>
29#include <linux/skbuff.h>
30#include <linux/in6.h>
31#include <linux/init.h>
32#include <asm/uaccess.h>
33#include <asm/checksum.h>
34#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0)
35#include <net/ip6_checksum.h>
36#endif
37#include <linux/in6.h>
38#include "siit.h"
39
40MODULE_AUTHOR("Dmitriy Moscalev, Grigory Klyuchnikov, Felix Fietkau");
41
42/*
43 * If tos_ignore_flag != 0, we don't copy TOS and Traffic Class
44 * from origin paket and set it to 0
45 */
46int tos_ignore_flag = 0;
47
48#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
49static inline void
50skb_reset_mac_header(struct sk_buff *skb)
51{
52    skb->mac.raw=skb->data;
53}
54
55static struct net_device_stats *
56siit_get_stats(struct net_device *dev)
57{
58    return netdev_priv(dev);
59}
60
61static inline void random_ether_addr(u8 *addr)
62{
63    get_random_bytes (addr, ETH_ALEN);
64    addr [0] &= 0xfe; /* clear multicast bit */
65    addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
66}
67
68
69#define siit_stats(_dev) ((struct net_device_stats *)netdev_priv(_dev))
70#else
71#define siit_stats(_dev) (&(_dev)->stats)
72#endif
73
74/*
75 * The Utility stuff
76 */
77
78#ifdef SIIT_DEBUG
79/* print dump bytes (data point data area sizeof len and message
80 * before dump.
81 */
82static int siit_print_dump(char *data, int len, char *message)
83{
84    int i;
85    int j = 0, k = 1;
86
87    len = len > BUFF_SIZE ? BUFF_SIZE : len;
88    printk("%s:\n", message);
89    for (i=0; i < len; i++, k++) {
90        if( i == len-1 || k == 16) {
91            printk("%02x\n", (~(~0 << 8) & *(data+i)));
92            j = 0;
93            k = 0;
94        }
95        else if (j) {
96            printk("%02x ", (~(~0 << 8) & *(data+i)));
97            j--;
98        }
99        else {
100            printk("%02x", (~(~0 << 8) & *(data+i)));
101            j++;
102        }
103    }
104    return 0;
105}
106#endif
107
108/*
109 * Open and close
110 */
111static int siit_open(struct net_device *dev)
112{
113    netif_start_queue(dev);
114    return 0;
115}
116
117
118static int siit_release(struct net_device *dev)
119{
120    netif_stop_queue(dev); /* can't transmit any more */
121    return 0;
122}
123
124/*
125 * Translation IPv4 to IPv6 stuff
126 *
127 * ip4_ip6 (src, len, dst, include_flag)
128 *
129 * where
130 * src - buffer with original IPv4 packet,
131 * len - size of original packet,
132 * dst - new buffer for IPv6 packet,
133 * include_flag - if = 1, dst point to IPv4 packet that is ICMP error
134 * included IP packet, else = 0
135 */
136
137static int ip4_ip6(char *src, int len, char *dst, int include_flag)
138{
139    struct iphdr *ih4 = (struct iphdr *) src; /* point to current IPv4 header struct */
140    struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
141    struct udphdr *udp_hdr; /* point to current IPv4 UDP header struct */
142
143    struct ipv6hdr *ih6 = (struct ipv6hdr *) dst; /* point to current IPv6 header struct */
144    struct frag_hdr *ih6_frag = (struct frag_hdr *)(dst+sizeof(struct ipv6hdr));
145                                              /* point to current IPv6 fragment header struct */
146    struct icmp6hdr *icmp6_hdr; /* point to current ICMPv6 header */
147
148    int hdr_len = (int)(ih4->ihl * 4); /* IPv4 header length */
149    int icmp_len; /* ICMPv4 packet length */
150    int plen; /* payload length */
151
152    unsigned int csum; /* need to calculate ICMPv6 and UDP checksum */
153    int fl_csum = 0; /* flag to calculate UDP checksum */
154    int icmperr = 1; /* flag to indicate ICMP error message and to need
155                                   translate ICMP included IP packet */
156    int fr_flag = 0; /* fragment flag, if = 0 - don't add
157                                   fragment header */
158    __u16 new_tot_len; /* need to calculate IPv6 total length */
159    __u8 new_nexthdr; /* next header code */
160    __u16 icmp_ptr = 0; /* Pointer field in ICMP_PARAMETERPROB */
161
162#ifdef SIIT_DEBUG /* print IPv4 header dump */
163    siit_print_dump(src, hdr_len, "siit: ip4_ip6() (in) ip4 header dump");
164#endif
165
166    /* If DF == 1 && MF == 0 && Fragment Offset == 0
167     * or this packet is ICMP included IP packet
168     * we don't need fragment header */
169    if (ntohs(ih4->frag_off) == IP_DF || include_flag ) {
170        /* not fragment and we need not to add Fragment
171         * Header to IPv6 packet. */
172        /* total length = total length from IPv4 packet */
173        new_tot_len = ntohs(ih4->tot_len);
174
175        if (ih4->protocol == IPPROTO_ICMP)
176            new_nexthdr = NEXTHDR_ICMP;
177        else
178            new_nexthdr = ih4->protocol;
179    }
180    else {
181        /* need to add Fragment Header */
182        fr_flag = 1;
183        /* total length = total length from IPv4 packet +
184           length of Fragment Header */
185        new_tot_len = ntohs(ih4->tot_len) + sizeof(struct frag_hdr);
186        /* IPv6 Header NextHeader = NEXTHDR_FRAGMENT */
187        new_nexthdr = NEXTHDR_FRAGMENT;
188        /* Fragment Header NextHeader copy from IPv4 packet */
189        if (ih4->protocol == IPPROTO_ICMP)
190            ih6_frag->nexthdr = NEXTHDR_ICMP;
191        else
192            ih6_frag->nexthdr = ih4->protocol;
193
194        /* copy frag offset from IPv4 packet */
195        ih6_frag->frag_off = htons((ntohs(ih4->frag_off) & IP_OFFSET) << 3);
196        /* copy MF flag from IPv4 packet */
197        ih6_frag->frag_off = htons((ntohs(ih6_frag->frag_off) |
198                                    ((ntohs(ih4->frag_off) & IP_MF) >> 13)));
199        /* copy Identification field from IPv4 packet */
200        ih6_frag->identification = htonl(ntohs(ih4->id));
201        /* reserved field initialized to zero */
202        ih6_frag->reserved = 0;
203    }
204
205    /* Form rest IPv6 fields */
206
207    /*
208     * At this point we need to add checking of unxpired source
209     * route optin and if it is, send ICMPv4 "destination
210     * unreacheble/source route failes" Type 3/Code 5 and
211     * drop packet. (NOT RELEASED YET)
212     */
213
214    /* IP version = 6 */
215    ih6->version = 6;
216
217    if (tos_ignore_flag) {
218        ih6->priority = 0;
219        ih6->flow_lbl[0] = 0;
220    } else {
221        ih6->priority = (ih4->tos & 0xf0) >> 4;
222        ih6->flow_lbl[0] = (ih4->tos & 0x0f) << 4;
223    }
224    ih6->flow_lbl[1] = 0;
225    ih6->flow_lbl[2] = 0;
226
227    /* Hop Limit = IPv4 TTL */
228    ih6->hop_limit = ih4->ttl;
229
230    /* Translate source destination addresses,
231       for IPv6 host it's IPv4-translated IPv6 address,
232       for IPv4 host it's IPv4-mapped IPv6 address
233
234       !!WARNING!! Instead IPv4-mapped IPv6 addresses we use addreesses
235       with unused prefix ::ffff:ffff:0:0/96, because KAME implementation
236       doesn't support IPv4-mapped addresses in IPv6 packets and discard them.
237
238    */
239
240    if (include_flag) {
241        /*
242           It's ICMP included IP packet and there is a diffirence
243           in src/dst addresses then src/dst in normal direction
244         */
245
246        /*
247           Source address
248           is IPv4-translated IPv6 address because packet traveled
249           from IPv6 to IPv4 area
250        */
251        ih6->saddr.in6_u.u6_addr32[0] = 0;
252        ih6->saddr.in6_u.u6_addr32[1] = 0;
253        ih6->saddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
254        ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
255
256        /*
257           Destination address
258           is IPv4-mapped address (but it's not IPv4- mapped, we use
259           prefix ::ffff:ffff:0:0/96
260         */
261        ih6->daddr.in6_u.u6_addr32[0] = 0;
262        ih6->daddr.in6_u.u6_addr32[1] = 0;
263        ih6->daddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
264        ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
265    }
266    else {
267
268        /*
269           This is normal case (packet isn't included IP packet)
270
271           Source address
272           is IPv4-mapped address (but it's not IPv4- mapped, we use
273           prefix ::ffff:ffff:0:0/96)
274        */
275        ih6->saddr.in6_u.u6_addr32[0] = 0;
276        ih6->saddr.in6_u.u6_addr32[1] = 0;
277        ih6->saddr.in6_u.u6_addr32[2] = htonl(MAPPED_PREFIX); /* to network order bytes */
278        ih6->saddr.in6_u.u6_addr32[3] = ih4->saddr;
279
280        /* Destination address
281           is is IPv4-translated IPv6 address
282         */
283        ih6->daddr.in6_u.u6_addr32[0] = 0;
284        ih6->daddr.in6_u.u6_addr32[1] = 0;
285        ih6->daddr.in6_u.u6_addr32[2] = htonl(TRANSLATED_PREFIX); /* to network order bytes */
286        ih6->daddr.in6_u.u6_addr32[3] = ih4->daddr;
287    }
288
289    /* Payload Length */
290    plen = new_tot_len - hdr_len; /* Payload length = IPv4 total len - IPv4 header len */
291    ih6->payload_len = htons(plen);
292
293    /* Next Header */
294    ih6->nexthdr = new_nexthdr; /* Next Header */
295
296    /* Process ICMP protocols data */
297
298    switch (ih4->protocol) {
299    case IPPROTO_ICMP:
300        if ( (ntohs(ih4->frag_off) & IP_OFFSET) != 0 || (ntohs(ih4->frag_off) & IP_MF) != 0 ) {
301            PDEBUG("ip4_ip6(): don't translate ICMPv4 fragments - packet dropped.\n");
302            return -1;
303        }
304
305        icmp_hdr = (struct icmphdr *) (src+hdr_len); /* point to ICMPv4 header */
306        csum = 0;
307        icmp_len = ntohs(ih4->tot_len) - hdr_len; /* ICMPv4 packet length */
308        icmp6_hdr = (struct icmp6hdr *)(dst+sizeof(struct ipv6hdr)
309                                        +fr_flag*sizeof(struct frag_hdr)); /* point to ICMPv6 header */
310
311        if (include_flag) {
312            /* ICMPv4 packet cannot be included in ICMPv4 Error message */
313            /* !!! May be it's WRONG !!! ICMPv4 QUERY packet can be included
314               in ICMPv4 Error message */
315            PDEBUG("ip4_ip6(): It's included ICMPv4 in ICMPv4 Error message - packet dropped.\n");
316            return -1;
317        }
318
319        /* Check ICMPv4 Type field */
320        switch (icmp_hdr->type) {
321        /* ICMP Error messages */
322        /* Destination Unreachable (Type 3) */
323        case ICMP_DEST_UNREACH:
324            icmp6_hdr->icmp6_type = ICMPV6_DEST_UNREACH; /* to Type 1 */
325            icmp6_hdr->icmp6_unused = 0;
326            switch (icmp_hdr->code)
327            {
328            case ICMP_NET_UNREACH: /* Code 0 */
329            case ICMP_HOST_UNREACH: /* Code 1 */
330            case ICMP_SR_FAILED: /* Code 5 */
331            case ICMP_NET_UNKNOWN: /* Code 6 */
332            case ICMP_HOST_UNKNOWN: /* Code 7 */
333            case ICMP_HOST_ISOLATED: /* Code 8 */
334            case ICMP_NET_UNR_TOS: /* Code 11 */
335            case ICMP_HOST_UNR_TOS: /* Code 12 */
336                icmp6_hdr->icmp6_code = ICMPV6_NOROUTE; /* to Code 0 */
337                break;
338            case ICMP_PROT_UNREACH: /* Code 2 */
339                icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB; /* to Type 4 */
340                icmp6_hdr->icmp6_code = ICMPV6_UNK_NEXTHDR; /* to Code 1 */
341                /* Set pointer filed to 6, it's octet offset IPv6 Next Header field */
342                icmp6_hdr->icmp6_pointer = htonl(6);
343                break;
344            case ICMP_PORT_UNREACH: /* Code 3 */
345                icmp6_hdr->icmp6_code = ICMPV6_PORT_UNREACH; /* to Code 4 */
346                break;
347            case ICMP_FRAG_NEEDED: /* Code 4 */
348                icmp6_hdr->icmp6_type = ICMPV6_PKT_TOOBIG; /* to Type 2 */
349                icmp6_hdr->icmp6_code = 0;
350                /* Correct MTU */
351                if (icmp_hdr->un.frag.mtu == 0)
352                    /* we use minimum MTU for IPv4 PMTUv4 RFC1191, section 5;
353                       IPv6 implementation wouldn't accept Path MTU < 1280,
354                       but it records info correctly to always include
355                       a fragment header */
356                    icmp6_hdr->icmp6_mtu = htonl(576);
357                else
358                    /* needs to adjusted for difference between IPv4/IPv6 headers
359                     * SIIT RFC2765, section 3.3,
360                     * we assume that difference is 20 bytes */
361                    icmp6_hdr->icmp6_mtu = htonl(ntohs(icmp_hdr->un.frag.mtu)+IP4_IP6_HDR_DIFF);
362
363                break;
364            case ICMP_NET_ANO: /* Code 9 */
365            case ICMP_HOST_ANO: /* Code 10 */
366                icmp6_hdr->icmp6_code = ICMPV6_ADM_PROHIBITED; /* to Code 1 */
367                break;
368            default: /* discard any other Code */
369                PDEBUG("ip4_ip6(): Unknown ICMPv4 Type %d Code %d - packet dropped.\n",
370                       ICMP_DEST_UNREACH, icmp_hdr->code);
371                return -1;
372            }
373            break;
374            /* Time Exceeded (Type 11) */
375        case ICMP_TIME_EXCEEDED:
376            icmp6_hdr->icmp6_type = ICMPV6_TIME_EXCEED;
377            icmp6_hdr->icmp6_code = icmp_hdr->code;
378            break;
379            /* Parameter Problem (Type 12) */
380        case ICMP_PARAMETERPROB:
381            icmp6_hdr->icmp6_type = ICMPV6_PARAMPROB;
382            icmp6_hdr->icmp6_code = icmp_hdr->code;
383
384            icmp_ptr = ntohs(icmp_hdr->un.echo.id) >> 8;
385            switch (icmp_ptr) {
386            case 0:
387                icmp6_hdr->icmp6_pointer = 0; /* IPv4 Version -> IPv6 Version */
388                break;
389            case 2:
390                icmp6_hdr->icmp6_pointer = __constant_htonl(4); /* IPv4 length -> IPv6 Payload Length */
391                break;
392            case 8:
393                icmp6_hdr->icmp6_pointer = __constant_htonl(7); /* IPv4 TTL -> IPv6 Hop Limit */
394                break;
395            case 9:
396                icmp6_hdr->icmp6_pointer = __constant_htonl(6); /* IPv4 Protocol -> IPv6 Next Header */
397                break;
398            case 12:
399                icmp6_hdr->icmp6_pointer = __constant_htonl(8); /* IPv4 Src Addr -> IPv6 Src Addr */
400                break;
401            case 16:
402                icmp6_hdr->icmp6_pointer = __constant_htonl(24); /* IPv4 Dst Addr -> IPv6 Dst Addr */
403                break;
404            default:
405                icmp6_hdr->icmp6_pointer = 0xffffffff; /* set to all ones in any other cases */
406                break;
407            }
408            break;
409        case ICMP_ECHO:
410            icmperr = 0;
411            icmp6_hdr->icmp6_type = ICMPV6_ECHO_REQUEST;
412            icmp6_hdr->icmp6_code = 0;
413            /* Copy rest ICMP data to new IPv6 packet without changing */
414            memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
415            break;
416
417        case ICMP_ECHOREPLY:
418            icmperr = 0;
419            icmp6_hdr->icmp6_type = ICMPV6_ECHO_REPLY;
420            icmp6_hdr->icmp6_code = 0;
421            /* Copy rest ICMP data to new IPv6 packet without changing */
422            memcpy(((char *)icmp6_hdr)+4, ((char *)icmp_hdr)+4, len - hdr_len - 4);
423            break;
424
425            /* Discard any other ICMP messages */
426        default:
427            PDEBUG("ip4_ip6(): Unknown ICMPv4 packet Type %x - packet dropped.\n", icmp_hdr->type);
428            return -1;
429        }
430
431        /* Now if it's ICMPv4 Error message we must translate included IP packet */
432
433        if (icmperr) {
434            /* Call our ip4_ip6() to translate included IP packet */
435            if (ip4_ip6(src+hdr_len+sizeof(struct icmphdr), len - hdr_len - sizeof(struct icmphdr),
436                        dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr)
437                        +sizeof(struct icmp6hdr), 1) == -1) {
438                PDEBUG("ip4_ip6(): Uncorrect translation of ICMPv4 Error message - packet dropped.\n");
439                return -1;
440            }
441            /* correct ICMPv6 packet length for diffirence between IPv4 and IPv6 headers
442               in included IP packet
443               */
444            icmp_len += 20;
445            /* and correct Payload length for diffirence between IPv4 and IPv6 headers */
446            plen += 20;
447            ih6->payload_len = htons(plen);
448        }
449
450        /* Calculate ICMPv6 checksum */
451
452        icmp6_hdr->icmp6_cksum = 0;
453        csum = 0;
454
455        csum = csum_partial((u_char *)icmp6_hdr, icmp_len, csum);
456        icmp6_hdr->icmp6_cksum = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, icmp_len,
457                                             IPPROTO_ICMPV6, csum);
458        break;
459
460    /* Process TCP protocols data */
461    case IPPROTO_TCP:
462        /* Copy TCP data to new IPv6 packet without changing */
463        memcpy(dst+sizeof(struct ipv6hdr)+fr_flag*sizeof(struct frag_hdr),
464                   src+hdr_len, len - hdr_len);
465        break;
466
467    /* Process UDP protocols data */
468    case IPPROTO_UDP:
469        udp_hdr = (struct udphdr *)(src+hdr_len);
470        if ((ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
471            if ((ntohs(ih4->frag_off) & IP_MF) != 0) {
472                /* It's a first fragment */
473                if (udp_hdr->check == 0) {
474                    /* System management event */
475                    printk("siit: First fragment of UDP with zero checksum - packet droped\n");
476                    printk("siit: addr: %x src port: %d dst port: %d\n",
477                           htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
478                    return -1;
479                }
480            }
481            else if (udp_hdr->check == 0)
482                fl_csum = 1;
483        }
484
485        /* Copy UDP data to new IPv6 packet */
486        udp_hdr = (struct udphdr *)(dst+sizeof(struct ipv6hdr)
487                                    + fr_flag*sizeof(struct frag_hdr));
488        memcpy((char *)udp_hdr, src+hdr_len, len - hdr_len);
489
490        /* Calculate UDP checksum if UDP checksum in IPv4 packet was ZERO
491           and if it isn't included IP packet
492         */
493        if (fl_csum && (!include_flag)) {
494            udp_hdr->check = 0;
495            csum = 0;
496            csum = csum_partial((unsigned char *)udp_hdr, plen - fr_flag*sizeof(struct frag_hdr), csum);
497            udp_hdr->check = csum_ipv6_magic(&ih6->saddr, &ih6->daddr, plen -
498                                             fr_flag*sizeof(struct frag_hdr), IPPROTO_UDP, csum);
499        }
500        break;
501
502    /* Discard packets with any other protocol */
503    default:
504        PDEBUG("ip4_ip6(): Unknown upper protocol - packet dropped.\n");
505        return -1;
506    }
507
508#ifdef SIIT_DEBUG
509    siit_print_dump(dst, sizeof(struct ipv6hdr), "siit: ip4_ip6(): (out) ipv6 header dump");
510#endif
511
512    return 0;
513}
514
515/*
516 * Translation IPv6 to IPv4 stuff
517 *
518 * ip6_ip4(src, len, dst, include_flag)
519 *
520 * where
521 * src - buffer with original IPv6 packet,
522 * len - size of original packet,
523 * dst - new buffer for IPv4 packet,
524 * include_flag - if = 1, dst point to IPv6 packet that is ICMP error
525 * included IP packet, else = 0
526 *
527 */
528
529static int ip6_ip4(char *src, int len, char *dst, int include_flag)
530{
531    struct ipv6hdr *ip6_hdr; /* point to current IPv6 header struct */
532    struct iphdr *ip_hdr; /* point to current IPv4 header struct */
533    int opts_len = 0; /* to sum Option Headers length */
534    int icmperr = 1; /* if = 1, indicate that packet is ICMP Error message, else = 0 */
535    int ntot_len = 0; /* to calculate IPv6 Total Length field */
536    int real_len;
537    int len_delta;
538    int ip6_payload_len;
539    int inc_opts_len = 0; /* to sum Option Headers length in ICMP included IP packet */
540    __u8 next_hdr; /* Next Header */
541
542#ifdef SIIT_DEBUG
543    siit_print_dump(src, sizeof(struct ipv6hdr), "siit: ip6_ip4(): (in) ipv6 header dump");
544#endif
545
546    if ( (len_delta = len - sizeof(struct ipv6hdr)) >= 0)
547    {
548        ip6_hdr = (struct ipv6hdr *)src;
549        ip_hdr = (struct iphdr *)dst;
550
551        real_len = sizeof(struct iphdr);
552
553        /* Check validation of Saddr & Daddr? is a packet to fall under our translation? */
554        if (include_flag) { /* It's ICMP included IP packet,
555                               about process include_flag see comment in ip4_ip6() */
556            if (ip6_hdr->saddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
557                PDEBUG("ip6_ip4(): Included IP packet Src addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
558                       ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
559                       ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
560                return -1;
561            }
562            if ( ip6_hdr->daddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
563                PDEBUG("ip6_ip4(): Included IP packet Dst addr isn't translated addr: %x%x%x%x, packet dropped.\n",
564                       ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
565                       ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
566                return -1;
567            }
568        }
569        else { /* It's normal IP packet (not included in ICMP) */
570            if (ip6_hdr->saddr.s6_addr32[2] != htonl(TRANSLATED_PREFIX)) {
571                PDEBUG("ip6_ip4(): Src addr isn't translated addr: %x%x%x%x, packet dropped.\n",
572                       ip6_hdr->saddr.s6_addr32[0], ip6_hdr->saddr.s6_addr32[1],
573                       ip6_hdr->saddr.s6_addr32[2], ip6_hdr->saddr.s6_addr32[3]);
574                return -1;
575            }
576            if ( ip6_hdr->daddr.s6_addr32[2] != htonl(MAPPED_PREFIX)) {
577                PDEBUG("ip6_ip4(): Dst addr isn't mapped addr: %x%x%x%x, packet dropped.\n",
578                       ip6_hdr->daddr.s6_addr32[0], ip6_hdr->daddr.s6_addr32[1],
579                       ip6_hdr->daddr.s6_addr32[2], ip6_hdr->daddr.s6_addr32[3]);
580                return -1;
581            }
582        }
583
584        /* Set IPv4 Fragment Offset and ID to 0
585           before process any Option Headers */
586        ip_hdr->frag_off = 0;
587        ip_hdr->id = 0;
588
589        /*
590         * We process only Fragment Header. Any other options headers
591         * are ignored, i.e. there is no attempt to translate them.
592         * However, the Total Length field and the Protocol field would
593         * have to be adjusted to "skip" these extension headers.
594         */
595
596        next_hdr = ip6_hdr->nexthdr;
597
598        /* Hop_by_Hop options header (ip6_hdr->nexthdr = 0). It must
599         * appear only in IPv6 header's Next Header field.
600         */
601        if (next_hdr == NEXTHDR_HOP) {
602            if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
603            {
604                struct ipv6_opt_hdr *ip6h =
605                    (struct ipv6_opt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
606                if ( (len_delta -= ip6h->hdrlen*8 + 8) >= 0)
607                {
608                    opts_len += ip6h->hdrlen*8 + 8; /* See RFC 2460 page 11:
609                            Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by-
610                                         Hop Options header in 8-octet units, not
611                                         including the first 8 octets.
612                            */
613                    next_hdr = ip6h->nexthdr;
614                }
615                else
616                {
617                    PDEBUG("ip6_ip4(): hop_by_hop header error, packet droped");
618                    /* Generate ICMP Parameter Problem */
619                    return -1;
620                }
621            }
622        }
623
624        if (len_delta > 0)
625        {
626            while(next_hdr != NEXTHDR_ICMP && next_hdr != NEXTHDR_TCP
627                  && next_hdr != NEXTHDR_UDP)
628            {
629                /* Destination options header */
630                if (next_hdr == NEXTHDR_DEST)
631                {
632                    if ( (len_delta - sizeof(struct ipv6_opt_hdr)) >= 0)
633                    {
634                        struct ipv6_opt_hdr *ip6d =
635                            (struct ipv6_opt_hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
636                        if ( (len_delta -= ip6d->hdrlen*8 + 8) >= 0)
637                        {
638                            opts_len += ip6d->hdrlen*8 + 8;
639                            next_hdr = ip6d->nexthdr;
640                        }
641                    }
642                    else
643                    {
644                        PDEBUG("ip6_ip4(): destination header error, packet droped");
645                        /* Generate ICMP Parameter Problem */
646                        return -1;
647                    }
648                }
649                /* Routing options header */
650                else if (next_hdr == NEXTHDR_ROUTING)
651                {
652                    if ( (len_delta - sizeof(struct ipv6_rt_hdr)) >= 0)
653                    {
654                        struct ipv6_rt_hdr *ip6rt =
655                            (struct ipv6_rt_hdr *)(src+sizeof(struct ipv6hdr) + opts_len);
656                        /* RFC 2765 SIIT, 4.1:
657                           If a routing header with a non-zero Segments Left field is present
658                           then the packet MUST NOT be translated, and an ICMPv6 "parameter
659                           problem/ erroneous header field encountered" (Type 4/Code 0) error
660                           message, with the Pointer field indicating the first byte of the
661                           Segments Left field, SHOULD be returned to the sender.
662                           */
663                        if (ip6rt->segments_left != 0) {
664                            /* Build ICMPv6 "Parameter Problem/Erroneous Header
665                               Field Encountered" & drop the packet */
666                            /* !!! We don't send ICMPv6 "Parameter Problem" !!! */
667                            PDEBUG("ip6_ip4(): routing header type != 0\n");
668                            return -1;
669                        }
670                        if ( (len_delta -= ip6rt->hdrlen*8 + 8) >= 0)
671                        {
672                            opts_len += ip6rt->hdrlen*8 + 8;
673                            next_hdr = ip6rt->nexthdr;
674                        }
675                        else
676                        {
677                            PDEBUG("ip6_ip4(): routing header error, packet droped");
678                            /* Generate ICMP Parameter Problem */
679                            return -1;
680                        }
681                    }
682                }
683                /* Fragment options header */
684                else if (next_hdr == NEXTHDR_FRAGMENT)
685                {
686                    if ( (len_delta -= sizeof(struct frag_hdr)) >= 0)
687                    {
688                        struct frag_hdr *ip6f =
689                            (struct frag_hdr *)(src+sizeof(struct ipv6hdr)+opts_len);
690
691                        opts_len += sizeof(struct frag_hdr); /* Frag Header Length = 8 */
692                        ip_hdr->id = htons(ntohl(ip6f->identification)); /* ID field */
693                        ip_hdr->frag_off = htons((ntohs(ip6f->frag_off) & IP6F_OFF_MASK) >> 3);
694                                                                           /* fragment offset */
695                        ip_hdr->frag_off = htons(ntohs(ip_hdr->frag_off) |
696                                                 ((ntohs(ip6f->frag_off) & IP6F_MORE_FRAG) << 13));
697                                                                          /* more fragments flag */
698                        next_hdr = ip6f->nexthdr;
699                    }
700                    else
701                    {
702                        PDEBUG("ip6_ip4(): fragment header error, packet droped");
703                        /* Generate ICMP Parameter Problem */
704                        return -1;
705                    }
706                }
707                /* No Next Header */
708                else if (next_hdr == NEXTHDR_NONE)
709                {
710                    /* RFC 2460 IPv6 Specification, 4.7
711                       4.7 No Next Header
712
713                       The value 59 in the Next Header field of an IPv6 header or any
714                       extension header indicates that there is nothing following that
715                       header. If the Payload Length field of the IPv6 header indicates the
716                       presence of octets past the end of a header whose Next Header field
717                       contains 59, those octets must be ignored, and passed on unchanged if
718                       the packet is forwarded.
719                       */
720                    break;
721                }
722                else if (next_hdr == NEXTHDR_ESP || next_hdr == NEXTHDR_AUTH)
723                {
724                    PDEBUG("ip6_ip4(): cannot translate AUTH or ESP extention header, packet dropped\n");
725                    return -1;
726                }
727                else if (next_hdr == NEXTHDR_IPV6)
728                {
729                    PDEBUG("ip6_ip4(): cannot translate IPv6-IPv6 packet, packet dropped\n");
730                    return -1;
731                }
732                else if (next_hdr == 0)
733                {
734                    /* As say RFC 2460 (IPv6 Spec) we should discard the packet and send an
735                       ICMP Parameter Problem message to the source of the packet, with an
736                       ICMP Code value of 1 ("unrecognized Next Header type encountered")
737                       and the ICMP Pointer field containing the offset of the unrecognized
738                       value within the original packet
739                       */
740                    /* NOT IMPLEMENTED */
741                    PDEBUG("ip6_ip4(): NEXTHDR in extention header = 0, packet dropped\n");
742                    return -1;
743                }
744                else
745                {
746                    PDEBUG("ip6_ip4(): cannot translate extention header = %d, packet dropped\n", next_hdr);
747                    return -1;
748                }
749            }
750        }
751    }
752    else
753    {
754       PDEBUG("ip6_ip4(): error packet len, packet dropped.\n");
755       return -1;
756    }
757
758    /* Building ipv4 packet */
759
760    ip_hdr->version = IPVERSION;
761    ip_hdr->ihl = 5;
762
763    /* TOS see comment about TOS in ip4_ip6() */
764    if (tos_ignore_flag)
765        ip_hdr->tos = 0;
766    else {
767        ip_hdr->tos = ip6_hdr->priority << 4;
768        ip_hdr->tos = ip_hdr->tos | (ip6_hdr->flow_lbl[0] >> 4);
769    }
770
771    /* IPv4 Total Len = IPv6 Payload Len +
772       IPv4 Header Len (without options) - Options Headers Len */
773    ip6_payload_len = ntohs(ip6_hdr->payload_len);
774
775    if (ip6_payload_len == 0)
776        ntot_len = 0;
777    else
778        ntot_len = ip6_payload_len + IP4_IP6_HDR_DIFF - opts_len;
779
780    ip_hdr->tot_len = htons(ntot_len);
781
782    /* IPv4 TTL = IPv6 Hop Limit */
783    ip_hdr->ttl = ip6_hdr->hop_limit;
784
785    /* IPv4 Protocol = Next Header that will point to upper layer protocol */
786    ip_hdr->protocol = next_hdr;
787
788    /* IPv4 Src addr = last 4 bytes from IPv6 Src addr */
789    ip_hdr->saddr = ip6_hdr->saddr.s6_addr32[3];
790    /* IPv4 Dst addr = last 4 bytes from IPv6 Dst addr */
791    ip_hdr->daddr = ip6_hdr->daddr.s6_addr32[3];
792
793    /* Calculate IPv4 header checksum */
794    ip_hdr->check = 0;
795    ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
796
797    if (len_delta > 0)
798    {
799        /* PROCESS ICMP */
800
801        if (next_hdr == NEXTHDR_ICMP)
802        {
803            struct icmp6hdr *icmp6_hdr;
804            struct icmphdr *icmp_hdr;
805
806            if ((len_delta -= sizeof(struct icmp6hdr)) >= 0)
807            {
808                icmp6_hdr = (struct icmp6hdr *)(src + sizeof(struct ipv6hdr) + opts_len);
809                icmp_hdr = (struct icmphdr *)(dst + sizeof(struct iphdr));
810
811                real_len += len_delta + sizeof(struct icmphdr);
812
813                /* There is diffirent between ICMPv4/ICMPv6 protocol codes
814                   IPPROTO_ICMP = 1
815                   IPPROTO_ICMPV6 = 58 */
816                ip_hdr->protocol = IPPROTO_ICMP;
817
818                if (include_flag) {
819                    /* !!! Warnig !!! We discard ICMP packets with any ICMP as included
820                       in ICMP Error. But ICMP Error messages can include ICMP Query message
821                       */
822                    if (icmp6_hdr->icmp6_type != ICMPV6_ECHO_REQUEST)
823                    {
824                        PDEBUG("ip6_ip4(): included ICMPv6 in ICMPv6 Error message, packet dropped\n");
825                        return -1;
826                    }
827                }
828
829            /* Translate ICMPv6 to ICMPv4 */
830                switch (icmp6_hdr->icmp6_type)
831                {
832/* ICMP Error messages */
833            /* Destination Unreachable (Type 1) */
834                case ICMPV6_DEST_UNREACH: /* Type 1 */
835                    icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
836                    icmp_hdr->un.echo.id = 0;
837                    icmp_hdr->un.echo.sequence = 0;
838                    switch (icmp6_hdr->icmp6_code)
839                    {
840                    case ICMPV6_NOROUTE: /* Code 0 */
841                    case ICMPV6_NOT_NEIGHBOUR: /* Code 2 */
842                    case ICMPV6_ADDR_UNREACH: /* Code 3 */
843                        icmp_hdr->code = ICMP_HOST_UNREACH; /* To Code 1 */
844                        break;
845                    case ICMPV6_ADM_PROHIBITED: /* Code 1 */
846                        icmp_hdr->code = ICMP_HOST_ANO; /* To Code 10 */
847                        break;
848                    case ICMPV6_PORT_UNREACH: /* Code 4 */
849                        icmp_hdr->code = ICMP_PORT_UNREACH; /* To Code 3 */
850
851                        break;
852                    default: /* discard any other codes */
853                        PDEBUG("ip6_ip4(): Unknown ICMPv6 Type %d Code %d - packet dropped.\n",
854                               ICMPV6_DEST_UNREACH, icmp6_hdr->icmp6_code);
855                        return -1;
856                    }
857                    break;
858            /* Packet Too Big (Type 2) */
859                case ICMPV6_PKT_TOOBIG: /* Type 2 */
860                    icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
861                    icmp_hdr->code = ICMP_FRAG_NEEDED; /* to Code 4 */
862                    /* Change MTU, RFC 2765 (SIIT), 4.2:
863                       The MTU field needs to be adjusted for the difference between
864                       the IPv4 and IPv6 header sizes taking into account whether or
865                       not the packet in error includes a Fragment header.
866                       */
867                    /* !!! Don't implement !!! */
868                    icmp_hdr->un.frag.mtu = (__u16) icmp6_hdr->icmp6_mtu;
869                    break;
870            /* Time Exceeded (Type 3) */
871                case ICMPV6_TIME_EXCEED:
872                    icmp_hdr->type = ICMP_TIME_EXCEEDED; /* to Type 11 */
873                    icmp_hdr->code = icmp6_hdr->icmp6_code; /* Code unchanged */
874                    break;
875            /* Parameter Problem (Type 4) */
876                case ICMPV6_PARAMPROB:
877                    switch (icmp6_hdr->icmp6_code) {
878                    case ICMPV6_UNK_NEXTHDR: /* Code 1 */
879                        icmp_hdr->type = ICMP_DEST_UNREACH; /* to Type 3 */
880                        icmp_hdr->code = ICMP_PROT_UNREACH; /* to Code 2 */
881                        break;
882                    default: /* if Code != 1 */
883                        icmp_hdr->type = ICMP_PARAMETERPROB; /* to Type 12 */
884                        icmp_hdr->code = 0; /* to Code 0 */
885                        /* Update Pointer field
886                           RFC 2765 (SIIT), 4.2:
887                           The Pointer needs to be updated to point to the corresponding
888                           field in the translated include IP header.
889                           */
890                        switch (ntohl(icmp6_hdr->icmp6_pointer))
891                        {
892                        case 0: /* IPv6 Version -> IPv4 Version */
893                            icmp_hdr->un.echo.id = 0;
894                            break;
895                        case 4: /* IPv6 PayloadLength -> IPv4 Total Length */
896                            icmp_hdr->un.echo.id = 0x0002; /* 2 */
897                            break;
898                        case 6: /* IPv6 Next Header-> IPv4 Protocol */
899                            icmp_hdr->un.echo.id = 0x0009; /* 9 */
900                            break;
901                        case 7: /* IPv6 Hop Limit -> IPv4 TTL */
902                            icmp_hdr->un.echo.id = 0x0008; /* 8 */
903                            break;
904                        case 8: /* IPv6 Src addr -> IPv4 Src addr */
905                            icmp_hdr->un.echo.id = 0x000c; /* 12 */
906                            break;
907                        case 24: /* IPv6 Dst addr -> IPv4 Dst addr*/
908                            icmp_hdr->un.echo.id = 0x0010; /* 16 */
909                            break;
910                        default: /* set all ones in other cases */
911                            icmp_hdr->un.echo.id = 0xff;
912                            break;
913                        }
914                        break;
915                    }
916                    break;
917
918/* End of ICMP Error messages */
919
920            /* Echo Request and Echo Reply (Type 128 and 129) */
921                case ICMPV6_ECHO_REQUEST:
922                    icmperr = 0; /* not error ICMP message */
923                    icmp_hdr->type = ICMP_ECHO; /* to Type 8 */
924                    icmp_hdr->code = 0; /* to Code 0 */
925                    icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
926                    icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
927                    /* copy rest of ICMP data to result packet */
928                    if (len_delta > 0)
929                        memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
930                               ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
931                    break;
932                case ICMPV6_ECHO_REPLY:
933                    icmperr = 0; /* not error ICMP message */
934                    icmp_hdr->type = ICMP_ECHOREPLY; /* to Type 0 */
935                    icmp_hdr->code = 0; /* to Code 0 */
936                    icmp_hdr->un.echo.id = icmp6_hdr->icmp6_identifier;
937                    icmp_hdr->un.echo.sequence = icmp6_hdr->icmp6_sequence;
938                    /* copy rest of ICMP data */
939                    if (len_delta > 0)
940                        memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
941                               ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
942                    break;
943                default:
944                    /* Unknown error messages. Silently drop. */
945                    PDEBUG("ip6_ip4(): unknown ICMPv6 Type %d, packet dropped.\n", icmp6_hdr->icmp6_type);
946                    return -1;
947                }
948
949                if (icmperr)
950                {
951                    /* If ICMP Error message, we translate IP included packet*/
952                    if (len_delta >= sizeof(struct ipv6hdr))
953                    {
954                        if((inc_opts_len = ip6_ip4((char *)icmp6_hdr + sizeof(struct icmp6hdr), len_delta,
955                                                   (char *)icmp_hdr + sizeof(struct icmphdr), 1)) == -1) {
956                            PDEBUG("ip6_ip4(): incorrect translation of ICMPv6 Error message, packet dropped\n");
957                            return -1;
958                        }
959                        /* correct IPv4 Total Len that = old Total Len
960                           - Options Headers Len in included IP packet
961                           - diffirence between IPv6 Header Len and IPv4 Header Len
962                           */
963                        if (ntot_len != 0)
964                            ip_hdr->tot_len = htons(ntot_len - inc_opts_len - IP4_IP6_HDR_DIFF);
965                        real_len = real_len - inc_opts_len - IP4_IP6_HDR_DIFF;
966                    }
967                    else if (len_delta > 0)
968                    {
969                        /* May be it need set 0x0 to rest area in result IPv4 packet,
970                         * but we copy rest data unchanged
971                         */
972                        memcpy(((char *)icmp_hdr) + sizeof(struct icmphdr),
973                               ((char *)icmp6_hdr) + sizeof(struct icmp6hdr), len_delta);
974                    }
975                }
976
977                /* Calculate IPv4 Header checksum */
978                ip_hdr->check = 0;
979                ip_hdr->check = ip_fast_csum((unsigned char *)ip_hdr, ip_hdr->ihl);
980
981                /* Calculate ICMPv4 checksum */
982                if (ntot_len != 0)
983                {
984                    icmp_hdr->checksum = 0;
985                    icmp_hdr->checksum = ip_compute_csum((unsigned char *)icmp_hdr, ntohs(ip_hdr->tot_len)
986                                                     - sizeof(struct iphdr));
987                }
988            }
989            else
990            {
991                PDEBUG("ip6_ip4(): error length ICMP packet, packet dropped.\n");
992                return -1;
993            }
994
995        }
996        /* PROCESS TCP and UDP (and rest data) */
997
998        else {
999            real_len += len_delta;
1000            /* we copy rest data to IPv4 packet without changing */
1001            memcpy(dst+sizeof(struct iphdr), src + sizeof(struct ipv6hdr) + opts_len, len_delta);
1002        }
1003    }
1004
1005    if (include_flag) /* if it's included IP packet */
1006        return opts_len; /* return options headers length */
1007    else
1008        return real_len; /* result packet len */
1009}
1010
1011/*
1012 * ip4_fragment(skb, len, hdr_len, dev, eth_h)
1013 * to fragment original IPv4 packet if result IPv6 packet will be > 1280
1014 */
1015
1016static int ip4_fragment(struct sk_buff *skb, int len, int hdr_len, struct net_device *dev, struct ethhdr *eth_h)
1017{
1018    struct sk_buff *skb2 = NULL; /* pointer to new struct sk_buff for transleded packet */
1019    char buff[FRAG_BUFF_SIZE+hdr_len]; /* buffer to form new fragment packet */
1020    char *cur_ptr = skb->data+hdr_len; /* pointter to current packet data with len = frag_len */
1021    struct iphdr *ih4 = (struct iphdr *) skb->data;
1022    struct iphdr *new_ih4 = (struct iphdr *) buff; /* point to new IPv4 hdr */
1023    struct ethhdr *new_eth_h; /* point to ether hdr, need to set hard header data in fragment */
1024    int data_len = len - hdr_len; /* origin packet data len */
1025    int rest_len = data_len; /* rest data to fragment */
1026    int frag_len = 0; /* current fragment len */
1027    int last_frag = 0; /* last fragment flag, if = 1, it's last fragment */
1028    int flag_last_mf = 0;
1029    __u16 new_id = 0; /* to generate identification field */
1030    __u16 frag_offset = 0; /* fragment offset */
1031    unsigned int csum;
1032    unsigned short udp_len;
1033
1034#ifdef SIIT_DEBUG
1035    printk("siit: it's DF == 0 and result IPv6 packet will be > 1280\n");
1036    siit_print_dump(skb->data, hdr_len, "siit: (orig) ipv4_hdr dump");
1037#endif
1038
1039    if ((ntohs(ih4->frag_off) & IP_MF) == 0 )
1040        /* it's a case we'll clear MF flag in our last packet */
1041        flag_last_mf = 1;
1042
1043    if (ih4->protocol == IPPROTO_UDP) {
1044        if ( (ntohs(ih4->frag_off) & IP_OFFSET) == 0) {
1045            struct udphdr *udp_hdr = (struct udphdr *)((char *)ih4 + hdr_len);
1046            if (!flag_last_mf) {
1047                if (udp_hdr->check == 0) {
1048                    /* it's a first fragment with ZERO checksum and we drop packet */
1049                    printk("siit: First fragment of UDP with zero checksum - packet droped\n");
1050                    printk("siit: addr: %x src port: %d dst port: %d\n",
1051                           htonl(ih4->saddr), htons(udp_hdr->source), htons(udp_hdr->dest));
1052                    return -1;
1053                }
1054            }
1055            else if (udp_hdr->check == 0) {
1056                /* Calculate UDP checksum only if it's not fragment */
1057                udp_len = ntohs(udp_hdr->len);
1058                csum = 0;
1059                csum = csum_partial((unsigned char *)udp_hdr, udp_len, csum);
1060                udp_hdr->check = csum_tcpudp_magic(ih4->saddr, ih4->daddr, udp_len, IPPROTO_UDP, csum);
1061            }
1062        }
1063    }
1064
1065    frag_offset = ntohs(ih4->frag_off) & IP_OFFSET;
1066
1067    new_id = ih4->id;
1068
1069    while(1) {
1070        if (rest_len <= FRAG_BUFF_SIZE) {
1071            /* it's last fragmen */
1072            frag_len = rest_len; /* rest data */
1073            last_frag = 1;
1074        }
1075        else
1076            frag_len = FRAG_BUFF_SIZE;
1077
1078        /* copy IP header to buffer */
1079        memcpy(buff, skb->data, hdr_len);
1080        /* copy data to buffer with len = frag_len */
1081        memcpy(buff + hdr_len, cur_ptr, frag_len);
1082
1083        /* set id field in new IPv4 header*/
1084        new_ih4->id = new_id;
1085
1086        /* is it last fragmet */
1087        if(last_frag && flag_last_mf)
1088            /* clear MF flag */
1089            new_ih4->frag_off = htons(frag_offset & (~IP_MF));
1090        else
1091            /* set MF flag */
1092            new_ih4->frag_off = htons(frag_offset | IP_MF);
1093
1094        /* change packet total length */
1095        new_ih4->tot_len = htons(frag_len+hdr_len);
1096
1097        /* rebuild the header checksum (IP needs it) */
1098        new_ih4->check = 0;
1099        new_ih4->check = ip_fast_csum((unsigned char *)new_ih4,new_ih4->ihl);
1100
1101        /* Allocate new sk_buff to compose translated packet */
1102        skb2 = dev_alloc_skb(frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE);
1103        if (!skb2) {
1104            printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1105            dev_kfree_skb(skb2);
1106            return -1;
1107        }
1108        /* allocate skb->data portion for IP header len, fragment data len and ether header len
1109         * and copy to head ether header from origin skb
1110         */
1111        memcpy(skb_put(skb2, frag_len+hdr_len+dev->hard_header_len+IP4_IP6_HDR_DIFF+IP6_FRAGMENT_SIZE), (char *) eth_h,
1112               dev->hard_header_len);
1113        /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1114        new_eth_h = (struct ethhdr *)skb2->data;
1115        new_eth_h->h_proto = htons(ETH_P_IPV6);
1116
1117        /* reset the mac header */
1118        skb_reset_mac_header(skb2);
1119
1120        /* pull ether header from new skb->data */
1121        skb_pull(skb2, dev->hard_header_len);
1122        /* set skb protocol to IPV6 */
1123        skb2->protocol = htons(ETH_P_IPV6);
1124
1125        /* call translation function */
1126        if ( ip4_ip6(buff, frag_len+hdr_len, skb2->data, 0) == -1) {
1127            dev_kfree_skb(skb2);
1128            return -1;
1129        }
1130
1131        /*
1132         * Set needed fields in new sk_buff
1133         */
1134        skb2->dev = dev;
1135        skb2->ip_summed = CHECKSUM_UNNECESSARY;
1136        skb2->pkt_type = PACKET_HOST;
1137
1138        /* Add transmit statistic */
1139        siit_stats(dev)->tx_packets++;
1140        siit_stats(dev)->tx_bytes += skb2->len;
1141
1142        /* send packet to upper layer */
1143        netif_rx(skb2);
1144
1145        /* exit if it was last fragment */
1146        if (last_frag)
1147            break;
1148
1149        /* correct current data pointer */
1150        cur_ptr += frag_len;
1151        /* rest data len */
1152        rest_len -= frag_len;
1153        /* current fragment offset */
1154        frag_offset = (frag_offset*8 + frag_len)/8;
1155    }
1156
1157    return 0;
1158}
1159/*
1160 * Transmit a packet (called by the kernel)
1161 *
1162 * siit_xmit(skb, dev)
1163 *
1164 * where
1165 * skb - pointer to struct sk_buff with incomed packet
1166 * dev - pointer to struct device on which packet revieved
1167 *
1168 * Statistic:
1169 * for all incoming packes:
1170 * stats.rx_bytes+=skb->len
1171 * stats.rx_packets++
1172 * for packets we can't transle:
1173 * stats.tx_errors++
1174 * device busy:
1175 * stats.tx_errors++
1176 * for packets we can't allocate sk_buff:
1177 * stats.tx_dropped++
1178 * for outgoing packes:
1179 * stats.tx_packets++
1180 * stats.tx_bytes+=skb2->len !!! But we don't set skb2->len !!!
1181 */
1182
1183static int siit_xmit(struct sk_buff *skb, struct net_device *dev)
1184{
1185    struct sk_buff *skb2 = NULL;/* pointer to new struct sk_buff for transleded packet */
1186    struct ethhdr *eth_h; /* pointer to incoming Ether header */
1187    int len; /* original packets length */
1188    int new_packet_len;
1189    int skb_delta = 0; /* delta size for allocate new skb */
1190    char new_packet_buff[2048];
1191
1192    /* Check pointer to sk_buff and device structs */
1193    if (skb == NULL || dev == NULL)
1194        return -EINVAL;
1195
1196    /* Add receive statistic */
1197    siit_stats(dev)->rx_bytes += skb->len;
1198    siit_stats(dev)->rx_packets++;
1199
1200    dev->trans_start = jiffies;
1201
1202    /* Upper layer (IP) protocol forms sk_buff for outgoing packet
1203     * and sets IP header + Ether header too. IP layer sets outgoing
1204     * device in sk_buff->dev.
1205     * In function (from linux/net/core/dev.c) ther is a call to
1206     * device transmit function (dev->hard_start_xmit):
1207     *
1208     * dev_queue_xmit(struct sk_buff *skb)
1209     * {
1210     * ...
1211     * device *dev = skb->dev;
1212     * ...
1213     * dev->hard_start_xmit(skb, dev);
1214     * ...
1215     * }
1216     * We save pointer to ether header in eth_h and skb_pull ether header
1217     * from data field of skb_buff
1218     */
1219
1220    eth_h = (struct ethhdr *)skb->data; /* point to incoming packet Ether Header */
1221
1222#ifdef SIIT_DEBUG
1223    siit_print_dump(skb->data, ETH_HLEN, "siit: eth_hdr dump");
1224#endif
1225
1226    /* Remove hardware header from origin sk_buff */
1227    skb_pull(skb,dev->hard_header_len);
1228
1229    /*
1230     * Process IPv4 paket
1231     */
1232    if (ntohs(skb->protocol) == ETH_P_IP) {
1233        int hdr_len; /* IPv4 header length */
1234        int data_len; /* IPv4 data length */
1235        struct iphdr *ih4; /* pointer to IPv4 header */
1236        struct icmphdr *icmp_hdr; /* point to current ICMPv4 header struct */
1237
1238        ih4 = (struct iphdr *)skb->data; /* point to incoming packet's IPv4 header */
1239
1240        /* Check IPv4 Total Length */
1241        if (skb->len != ntohs(ih4->tot_len)) {
1242            PDEBUG("siit_xmit(): Different skb_len %x and ip4 tot_len %x - packet dropped.\n",
1243                   skb->len, ih4->tot_len);
1244            siit_stats(dev)->tx_errors++;
1245            dev_kfree_skb(skb);
1246            return 0;
1247        }
1248
1249        len = skb->len; /* packet's total len */
1250        hdr_len = (int)(ih4->ihl * 4); /* packet's header len */
1251        data_len = len - hdr_len; /* packet's data len */
1252
1253        /* If DF == 0 */
1254        if ( (ntohs(ih4->frag_off) & IP_DF) == 0 ) {
1255            /* If result IPv6 packet will be > 1280
1256               we need to fragment original IPv4 packet
1257            */
1258            if ( data_len > FRAG_BUFF_SIZE ) {
1259                /* call function that fragment packet and translate to IPv6 each fragment
1260                 * and send to upper layer
1261                 */
1262                if ( ip4_fragment(skb, len, hdr_len, dev, eth_h) == -1) {
1263                    siit_stats(dev)->tx_errors++;
1264                }
1265                /* Free incoming skb */
1266                dev_kfree_skb(skb);
1267                /* Device can accept a new packet */
1268
1269                return 0;
1270
1271            }
1272        }
1273        /* If DF == 1 && MF == 0 && Fragment Offset == 0
1274         * we don't include fragment header
1275         */
1276        if ( ntohs(ih4->frag_off) == IP_DF )
1277            skb_delta = IP4_IP6_HDR_DIFF; /* delta is +20 */
1278        else
1279            skb_delta = IP4_IP6_HDR_DIFF + IP6_FRAGMENT_SIZE; /* delta is +20 and +8 */
1280
1281        /* If it's ICMP, check is it included IP packet in it */
1282        if ( ih4->protocol == IPPROTO_ICMP) {
1283            icmp_hdr = (struct icmphdr *) (skb->data+hdr_len); /* point to ICMPv4 header */
1284            if ( icmp_hdr->type != ICMP_ECHO && icmp_hdr->type != ICMP_ECHOREPLY) {
1285                /*
1286                 * It's ICMP Error that has included IP packet
1287                 * we'll add only +20 because we don't include Fragment Header
1288                 * into translated included IP packet
1289                 */
1290                skb_delta += IP4_IP6_HDR_DIFF;
1291            }
1292        }
1293
1294        /* Allocate new sk_buff to compose translated packet */
1295        skb2 = dev_alloc_skb(len+dev->hard_header_len+skb_delta);
1296        if (!skb2) {
1297            printk(KERN_DEBUG "%s: alloc_skb failure - packet dropped.\n", dev->name);
1298            dev_kfree_skb(skb);
1299            siit_stats(dev)->rx_dropped++;
1300
1301            return 0;
1302        }
1303        /* allocate skb->data portion = IPv4 packet len + ether header len
1304         * + skb_delta (max = two times (diffirence between IPv4 header and
1305         * IPv6 header + Frag Header), second for included packet,
1306         * and copy to head of skb->data ether header from origin skb
1307         */
1308        memcpy(skb_put(skb2, len+dev->hard_header_len+skb_delta), (char *)eth_h, dev->hard_header_len);
1309        /* correct ether header data, ether protocol field to ETH_P_IPV6 */
1310        eth_h = (struct ethhdr *)skb2->data;
1311        eth_h->h_proto = htons(ETH_P_IPV6);
1312        skb_reset_mac_header(skb2);
1313        /* remove ether header from new skb->data,
1314         * NOTE! data will rest, pointer to data and data len will change
1315         */
1316        skb_pull(skb2,dev->hard_header_len);
1317        /* set skb protocol to IPV6 */
1318        skb2->protocol = htons(ETH_P_IPV6);
1319
1320        /* call translation function */
1321        if (ip4_ip6(skb->data, len, skb2->data, 0) == -1 ) {
1322            dev_kfree_skb(skb);
1323            dev_kfree_skb(skb2);
1324            siit_stats(dev)->rx_errors++;
1325
1326            return 0;
1327        }
1328    }
1329    /*
1330     * IPv6 paket
1331     */
1332    else if (ntohs(skb->protocol) == ETH_P_IPV6) {
1333
1334#ifdef SIIT_DEBUG
1335        siit_print_dump(skb->data, sizeof(struct ipv6hdr), "siit: (in) ip6_hdr dump");
1336#endif
1337        /* packet len = skb->data len*/
1338        len = skb->len;
1339
1340        /* call translation function */
1341        if ((new_packet_len = ip6_ip4(skb->data, len, new_packet_buff, 0)) == -1 )
1342        {
1343            PDEBUG("siit_xmit(): error translation ipv6->ipv4, packet dropped.\n");
1344            siit_stats(dev)->rx_dropped++;
1345            goto end;
1346        }
1347
1348        /* Allocate new sk_buff to compose translated packet */
1349        skb2 = dev_alloc_skb(new_packet_len + dev->hard_header_len);
1350        if (!skb2) {
1351            printk(KERN_DEBUG "%s: alloc_skb failure, packet dropped.\n", dev->name);
1352            siit_stats(dev)->rx_dropped++;
1353            goto end;
1354        }
1355        memcpy(skb_put(skb2, new_packet_len + dev->hard_header_len), (char *)eth_h, dev->hard_header_len);
1356        eth_h = (struct ethhdr *)skb2->data;
1357        eth_h->h_proto = htons(ETH_P_IP);
1358        skb_reset_mac_header(skb2);
1359        skb_pull(skb2, dev->hard_header_len);
1360        memcpy(skb2->data, new_packet_buff, new_packet_len);
1361        skb2->protocol = htons(ETH_P_IP);
1362    }
1363    else {
1364        PDEBUG("siit_xmit(): unsupported protocol family %x, packet dropped.\n", skb->protocol);
1365        goto end;
1366    }
1367
1368    /*
1369     * Set needed fields in new sk_buff
1370     */
1371    skb2->pkt_type = PACKET_HOST;
1372    skb2->dev = dev;
1373    skb2->ip_summed = CHECKSUM_UNNECESSARY;
1374
1375    /* Add transmit statistic */
1376    siit_stats(dev)->tx_packets++;
1377    siit_stats(dev)->tx_bytes += skb2->len;
1378
1379    /* Send packet to upper layer protocol */
1380    netif_rx(skb2);
1381
1382end:
1383    dev_kfree_skb(skb);
1384
1385    return 0;
1386}
1387
1388#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0)
1389static bool header_ops_init = false;
1390static struct header_ops siit_header_ops ____cacheline_aligned;
1391#endif
1392
1393#if !(defined CONFIG_COMPAT_NET_DEV_OPS) && LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
1394static const struct net_device_ops siit_netdev_ops = {
1395    .ndo_open = siit_open,
1396    .ndo_stop = siit_release,
1397    .ndo_start_xmit = siit_xmit,
1398};
1399#endif
1400
1401/*
1402 * The init function initialize of the SIIT device..
1403 * It is invoked by register_netdev()
1404 */
1405
1406static void
1407siit_init(struct net_device *dev)
1408{
1409    ether_setup(dev); /* assign some of the fields */
1410    random_ether_addr(dev->dev_addr);
1411
1412    /*
1413     * Assign device function.
1414     */
1415#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,30)
1416    dev->open = siit_open;
1417    dev->stop = siit_release;
1418    dev->hard_start_xmit = siit_xmit;
1419#else
1420#if !(defined CONFIG_COMPAT_NET_DEV_OPS) && LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
1421    dev->netdev_ops = &siit_netdev_ops;
1422#endif
1423#endif
1424    dev->flags |= IFF_NOARP; /* ARP not used */
1425    dev->tx_queue_len = 10;
1426
1427#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
1428    dev->hard_header_cache = NULL; /* Disable caching */
1429    memset(netdev_priv(dev), 0, sizeof(struct net_device_stats));
1430    dev->get_stats = siit_get_stats;
1431#else
1432    if (!header_ops_init) {
1433        memcpy(&siit_header_ops, dev->header_ops, sizeof(struct header_ops));
1434        siit_header_ops.cache = NULL;
1435    }
1436    dev->header_ops = &siit_header_ops;
1437#endif
1438}
1439
1440/*
1441 * Finally, the module stuff
1442 */
1443static struct net_device *siit_dev = NULL;
1444
1445int init_module(void)
1446{
1447    int res = -ENOMEM;
1448    int priv_size;
1449
1450#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
1451    priv_size = sizeof(struct net_device_stats);
1452#else
1453    priv_size = sizeof(struct header_ops);
1454#endif
1455    siit_dev = alloc_netdev(priv_size, "siit%d", siit_init);
1456    if (!siit_dev)
1457        goto err_alloc;
1458
1459    res = register_netdev(siit_dev);
1460    if (res)
1461        goto err_register;
1462
1463    return 0;
1464
1465err_register:
1466    free_netdev(siit_dev);
1467err_alloc:
1468    printk(KERN_ERR "Error creating siit device: %d\n", res);
1469    return res;
1470}
1471
1472void cleanup_module(void)
1473{
1474    unregister_netdev(siit_dev);
1475    free_netdev(siit_dev);
1476}
1477
1478
1479

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