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/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
36MODULE_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 */
42int tos_ignore_flag = 0;
43
44#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
45static inline void
46skb_reset_mac_header(struct sk_buff *skb)
47{
48    skb->mac.raw=skb->data;
49}
50
51static struct net_device_stats *
52siit_get_stats(struct net_device *dev)
53{
54    return netdev_priv(dev);
55}
56
57static 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 */
78static 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 */
107static int siit_open(struct net_device *dev)
108{
109    netif_start_queue(dev);
110    return 0;
111}
112
113
114static 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
133static 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
525static 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
1012static 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
1179static 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
1378end:
1379    dev_kfree_skb(skb);
1380
1381    return 0;
1382}
1383
1384#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0)
1385static bool header_ops_init = false;
1386static 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)
1390static 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
1402static void
1403siit_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 */
1439static struct net_device *siit_dev = NULL;
1440
1441int 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
1461err_register:
1462    free_netdev(siit_dev);
1463err_alloc:
1464    printk(KERN_ERR "Error creating siit device: %d\n", res);
1465    return res;
1466}
1467
1468void cleanup_module(void)
1469{
1470    unregister_netdev(siit_dev);
1471    free_netdev(siit_dev);
1472}
1473
1474
1475

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