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nfqws: support QUIC multi packet CRYPTO fragmentation

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bol-van 2025-03-23 23:28:47 +03:00
parent 77df43b9cb
commit 66fda2c33d
3 changed files with 103 additions and 37 deletions

98
nfq/desync.c

@ -1953,29 +1953,80 @@ static uint8_t dpi_desync_udp_packet_play(bool replay, size_t reasm_offset, uint
return verdict; // cannot be first packet
}
}
uint8_t defrag[16384];
size_t hello_offset, hello_len, defrag_len = sizeof(defrag);
if (QUICDefragCrypto(pclean,clean_len,defrag,&defrag_len))
bool bFull;
if (QUICDefragCrypto(pclean,clean_len,defrag,&defrag_len,&bFull))
{
bool bIsHello = IsQUICCryptoHello(defrag, defrag_len, &hello_offset, &hello_len);
bool bReqFull = bIsHello ? IsTLSHandshakeFull(defrag+hello_offset,hello_len) : false;
DLOG(bIsHello ? bReqFull ? "packet contains full TLS ClientHello\n" : "packet contains partial TLS ClientHello\n" : "packet does not contain TLS ClientHello\n");
if (ctrack)
if (bFull)
{
if (bIsHello && !bReqFull && ReasmIsEmpty(&ctrack->reasm_orig))
bool bIsHello = IsQUICCryptoHello(defrag, defrag_len, &hello_offset, &hello_len);
bool bReqFull = bIsHello ? IsTLSHandshakeFull(defrag+hello_offset,hello_len) : false;
DLOG(bIsHello ? bReqFull ? "packet contains full TLS ClientHello\n" : "packet contains partial TLS ClientHello\n" : "packet does not contain TLS ClientHello\n");
if (ctrack)
{
// preallocate max buffer to avoid reallocs that cause memory copy
if (!reasm_orig_start(ctrack,IPPROTO_UDP,16384,16384,clean,clean_len))
if (bIsHello && !bReqFull && ReasmIsEmpty(&ctrack->reasm_orig))
{
// preallocate max buffer to avoid reallocs that cause memory copy
if (!reasm_orig_start(ctrack,IPPROTO_UDP,16384,16384,clean,clean_len))
{
reasm_orig_cancel(ctrack);
return verdict;
}
}
if (!ReasmIsEmpty(&ctrack->reasm_orig))
{
verdict_udp_csum_fix(verdict, dis->udp, dis->transport_len, dis->ip, dis->ip6);
if (rawpacket_queue(&ctrack->delayed, &dst, desync_fwmark, ifout, dis->data_pkt, dis->len_pkt, dis->len_payload))
{
DLOG("DELAY desync until reasm is complete (#%u)\n", rawpacket_queue_count(&ctrack->delayed));
}
else
{
DLOG_ERR("rawpacket_queue failed !\n");
reasm_orig_cancel(ctrack);
return verdict;
}
if (bReqFull)
{
replay_queue(&ctrack->delayed);
reasm_orig_fin(ctrack);
}
return ct_new_postnat_fix_udp(ctrack, dis->ip, dis->ip6, dis->udp, &dis->len_pkt);
}
}
if (bIsHello)
{
bHaveHost = TLSHelloExtractHostFromHandshake(defrag + hello_offset, hello_len, host, sizeof(host), TLS_PARTIALS_ENABLE);
if (!bHaveHost && dp->desync_skip_nosni)
{
reasm_orig_cancel(ctrack);
DLOG("not applying tampering to QUIC ClientHello without hostname in the SNI\n");
return verdict;
}
}
if (!ReasmIsEmpty(&ctrack->reasm_orig))
else
{
if (!quic_reasm_cancel(ctrack,"QUIC initial without ClientHello")) return verdict;
}
}
else
{
DLOG("QUIC initial contains CRYPTO without full fragment coverage\n");
if (ctrack)
{
if (ReasmIsEmpty(&ctrack->reasm_orig))
{
// preallocate max buffer to avoid reallocs that cause memory copy
if (!reasm_orig_start(ctrack,IPPROTO_UDP,16384,16384,clean,clean_len))
{
reasm_orig_cancel(ctrack);
return verdict;
}
}
verdict_udp_csum_fix(verdict, dis->udp, dis->transport_len, dis->ip, dis->ip6);
if (rawpacket_queue(&ctrack->delayed, &dst, desync_fwmark, ifout, dis->data_pkt, dis->len_pkt, dis->len_payload))
{
@ -1987,28 +2038,9 @@ static uint8_t dpi_desync_udp_packet_play(bool replay, size_t reasm_offset, uint
reasm_orig_cancel(ctrack);
return verdict;
}
if (bReqFull)
{
replay_queue(&ctrack->delayed);
reasm_orig_fin(ctrack);
}
return ct_new_postnat_fix_udp(ctrack, dis->ip, dis->ip6, dis->udp, &dis->len_pkt);
}
}
if (bIsHello)
{
bHaveHost = TLSHelloExtractHostFromHandshake(defrag + hello_offset, hello_len, host, sizeof(host), TLS_PARTIALS_ENABLE);
if (!bHaveHost && dp->desync_skip_nosni)
{
reasm_orig_cancel(ctrack);
DLOG("not applying tampering to QUIC ClientHello without hostname in the SNI\n");
return verdict;
}
}
else
{
if (!quic_reasm_cancel(ctrack,"QUIC initial without ClientHello")) return verdict;
if (!quic_reasm_cancel(ctrack,"QUIC initial fragmented CRYPTO")) return verdict;
}
}
else
@ -2027,7 +2059,7 @@ static uint8_t dpi_desync_udp_packet_play(bool replay, size_t reasm_offset, uint
{
// received payload without host. it means we are out of the request retransmission phase. stop counter
ctrack_stop_retrans_counter(ctrack);
reasm_orig_cancel(ctrack);
if (IsWireguardHandshakeInitiation(dis->data_payload,dis->len_payload))

39
nfq/protocol.c

@ -844,7 +844,16 @@ bool QUICDecryptInitial(const uint8_t *data, size_t data_len, uint8_t *clean, si
return !memcmp(data + pn_offset + pkn_len + cryptlen, atag, 16);
}
bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,size_t *defrag_len)
struct range64
{
uint64_t offset,len;
};
#define MAX_DEFRAG_PIECES 128
static int cmp_range64(const void * a, const void * b)
{
return (((struct range64*)a)->offset < ((struct range64*)b)->offset) ? -1 : (((struct range64*)a)->offset > ((struct range64*)b)->offset) ? 1 : 0;
}
bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,size_t *defrag_len, bool *bFull)
{
// Crypto frame can be split into multiple chunks
// chromium randomly splits it and pads with zero/one bytes to force support the standard
@ -853,13 +862,15 @@ bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,siz
if (*defrag_len<10) return false;
uint8_t *defrag_data = defrag+10;
size_t defrag_data_len = *defrag_len-10;
uint8_t ft;
uint64_t offset,sz,szmax=0,zeropos=0,pos=0;
bool found=false;
struct range64 ranges[MAX_DEFRAG_PIECES];
int i,range=0;
while(pos<clean_len)
{
// frame type
ft = clean[pos];
pos++;
if (ft>1) // 00 - padding, 01 - ping
@ -867,6 +878,7 @@ bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,siz
if (ft!=6) return false; // dont want to know all possible frame type formats
if (pos>=clean_len) return false;
if (range>=MAX_DEFRAG_PIECES) return false;
if ((pos+tvb_get_size(clean[pos])>=clean_len)) return false;
pos += tvb_get_varint(clean+pos, &offset);
@ -875,7 +887,7 @@ bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,siz
pos += tvb_get_varint(clean+pos, &sz);
if ((pos+sz)>clean_len) return false;
if ((offset+sz)>defrag_data_len) return false;
if ((offset+sz)>defrag_data_len) return false; // defrag buf overflow
if (zeropos < offset)
// make sure no uninitialized gaps exist in case of not full fragment coverage
memset(defrag_data+zeropos,0,offset-zeropos);
@ -886,6 +898,10 @@ bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,siz
found=true;
pos+=sz;
ranges[range].offset = offset;
ranges[range].len = sz;
range++;
}
}
if (found)
@ -897,6 +913,23 @@ bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,siz
phton64(defrag+2,szmax);
defrag[2] |= 0xC0; // 64 bit value
*defrag_len = (size_t)(szmax+10);
qsort(ranges, range, sizeof(*ranges), cmp_range64);
for(i=0 ; i<range ; i++)
printf("RANGE %zu len %zu\n",ranges[i].offset,ranges[i].len);
for(i=0,offset=0,*bFull=true ; i<range ; i++)
{
if (ranges[i].offset!=offset)
{
*bFull = false;
break;
}
offset += ranges[i].len;
}
printf("bFull=%d\n",*bFull);
}
return found;
}

3
nfq/protocol.h

@ -87,5 +87,6 @@ uint8_t QUICDraftVersion(uint32_t version);
bool QUICExtractDCID(const uint8_t *data, size_t len, quic_cid_t *cid);
bool QUICDecryptInitial(const uint8_t *data, size_t data_len, uint8_t *clean, size_t *clean_len);
bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,size_t *defrag_len);
// returns true if crypto frames were found . bFull = true if crypto frame fragments have full coverage
bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,size_t *defrag_len, bool *bFull);
//bool QUICExtractHostFromInitial(const uint8_t *data, size_t data_len, char *host, size_t len_host, bool *bDecryptOK, bool *bIsCryptoHello);