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nfqws: ipv6 fragment at transport header

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bol-van
2022-01-05 15:34:57 +03:00
parent 85517a3851
commit 6b39411454
13 changed files with 42 additions and 32 deletions
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48
nfq/darkmagic.c
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@@ -346,42 +346,50 @@ bool ip_frag6(
uint8_t *pkt1, size_t *pkt1_size,
uint8_t *pkt2, size_t *pkt2_size)
{
uint16_t payload_len;
size_t payload_len, unfragmentable;
uint8_t *last_header_type;
uint8_t proto;
struct ip6_frag *frag;
const uint8_t *payload;
if (frag_pos & 7 || pkt_size < sizeof(struct ip6_hdr)) return false;
payload_len = htons(((struct ip6_hdr*)pkt)->ip6_ctlun.ip6_un1.ip6_un1_plen);
if ((sizeof(struct ip6_hdr)+payload_len)>pkt_size || frag_pos>=payload_len ||
*pkt1_size<(sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+frag_pos) ||
*pkt2_size<(sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+payload_len-frag_pos))
payload_len = sizeof(struct ip6_hdr) + htons(((struct ip6_hdr*)pkt)->ip6_ctlun.ip6_un1.ip6_un1_plen);
if (pkt_size < payload_len) return false;
payload = pkt;
proto_skip_ipv6((uint8_t**)&payload, &payload_len, &proto, &last_header_type);
unfragmentable = payload - pkt;
//printf("pkt_size=%zu FRAG_POS=%zu payload_len=%zu unfragmentable=%zu dh=%zu\n",pkt_size,frag_pos,payload_len,unfragmentable,last_header_type - pkt);
if (frag_pos>=payload_len ||
*pkt1_size<(unfragmentable + sizeof(struct ip6_frag) + frag_pos) ||
*pkt2_size<(unfragmentable + sizeof(struct ip6_frag) + payload_len - frag_pos))
{
return false;
}
proto = ((struct ip6_hdr*)pkt)->ip6_ctlun.ip6_un1.ip6_un1_nxt;
memcpy(pkt1, pkt, sizeof(struct ip6_hdr));
((struct ip6_hdr*)pkt1)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(sizeof(struct ip6_frag)+frag_pos);
((struct ip6_hdr*)pkt1)->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(((struct ip6_hdr*)pkt1)+1);
memcpy(pkt1, pkt, unfragmentable);
((struct ip6_hdr*)pkt1)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(unfragmentable - sizeof(struct ip6_hdr) + sizeof(struct ip6_frag) + frag_pos);
pkt1[last_header_type - pkt] = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(pkt1 + unfragmentable);
frag->ip6f_nxt = proto;
frag->ip6f_reserved = 0;
frag->ip6f_offlg = IP6F_MORE_FRAG;
frag->ip6f_ident = ident;
memcpy(frag+1, pkt+sizeof(struct ip6_hdr), frag_pos);
*pkt1_size = sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+frag_pos;
memcpy(frag+1, pkt + unfragmentable, frag_pos);
*pkt1_size = unfragmentable + sizeof(struct ip6_frag) + frag_pos;
memcpy(pkt2, pkt, sizeof(struct ip6_hdr));
((struct ip6_hdr*)pkt2)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(sizeof(struct ip6_frag)+payload_len-frag_pos);
((struct ip6_hdr*)pkt2)->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(((struct ip6_hdr*)pkt2)+1);
((struct ip6_hdr*)pkt2)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(unfragmentable - sizeof(struct ip6_hdr) + sizeof(struct ip6_frag) + payload_len - frag_pos);
pkt2[last_header_type - pkt] = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(pkt2 + unfragmentable);
frag->ip6f_nxt = proto;
frag->ip6f_reserved = 0;
frag->ip6f_offlg = htons(frag_pos);
frag->ip6f_ident = ident;
memcpy(frag+1, pkt+sizeof(struct ip6_hdr)+frag_pos, payload_len-frag_pos);
*pkt2_size = sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+payload_len-frag_pos;
memcpy(frag+1, pkt + unfragmentable + frag_pos, payload_len - frag_pos);
*pkt2_size = unfragmentable + sizeof(struct ip6_frag) + payload_len - frag_pos;
return true;
}
@@ -619,7 +627,7 @@ bool proto_check_ipv6(const uint8_t *data, size_t len)
}
// move to transport protocol
// proto_type = 0 => error
void proto_skip_ipv6(uint8_t **data, size_t *len, uint8_t *proto_type)
void proto_skip_ipv6(uint8_t **data, size_t *len, uint8_t *proto_type, uint8_t **last_header_type)
{
size_t hdrlen;
uint8_t HeaderType;
@@ -627,6 +635,7 @@ void proto_skip_ipv6(uint8_t **data, size_t *len, uint8_t *proto_type)
if (proto_type) *proto_type = 0; // put error in advance
HeaderType = (*data)[6]; // NextHeader field
if (last_header_type) *last_header_type = (*data)+6;
*data += 40; *len -= 40; // skip ipv6 base header
while (*len > 0) // need at least one byte for NextHeader field
{
@@ -654,6 +663,7 @@ void proto_skip_ipv6(uint8_t **data, size_t *len, uint8_t *proto_type)
}
if (*len < hdrlen) return; // error
HeaderType = **data;
if (last_header_type) *last_header_type = *data;
// advance to the next header location
*len -= hdrlen;
*data += hdrlen;