Carry split and detection functions to separate file

This needed to escape code duplication in further development of kernel
module. Also this cleanups the code.
This commit is contained in:
Vadim Vetrov 2024-07-30 23:10:00 +03:00
parent 460c727dea
commit 7490658708
No known key found for this signature in database
GPG Key ID: E8A308689D7A73A5
4 changed files with 546 additions and 377 deletions

View File

@ -17,7 +17,7 @@ export CC LD CFLAGS LDFLAGS
APP:=$(BUILD_DIR)/youtubeUnblock APP:=$(BUILD_DIR)/youtubeUnblock
SRCS := youtubeUnblock.c SRCS := youtubeUnblock.c mangle.c
OBJS := $(SRCS:%.c=$(BUILD_DIR)/%.o) OBJS := $(SRCS:%.c=$(BUILD_DIR)/%.o)
LIBNFNETLINK := $(DEPSDIR)/lib/libnfnetlink.a LIBNFNETLINK := $(DEPSDIR)/lib/libnfnetlink.a

430
mangle.c Normal file
View File

@ -0,0 +1,430 @@
#include "mangle.h"
#include <endian.h>
#ifdef KERNEL_SPACE
static __u16 nfq_checksum(__u32 sum, __u16 *buf, int size)
{
while (size > 1) {
sum += *buf++;
size -= sizeof(__u16);
}
if (size) {
#if __BYTE_ORDER == __BIG_ENDIAN
sum += (uint16_t)*(uint8_t *)buf << 8;
#else
sum += (__u16)*(__u8 *)buf;
#endif
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return (__u16)(~sum);
}
static __u16 nfq_checksum_tcpudp_ipv4(struct iphdr *iph, __u16 protonum)
{
__u32 sum = 0;
__u32 iph_len = iph->ihl*4;
__u32 len = ntohs(iph->tot_len) - iph_len;
__u8 *payload = (__u8 *)iph + iph_len;
sum += (iph->saddr >> 16) & 0xFFFF;
sum += (iph->saddr) & 0xFFFF;
sum += (iph->daddr >> 16) & 0xFFFF;
sum += (iph->daddr) & 0xFFFF;
sum += htons(protonum);
sum += htons(len);
return nfq_checksum(sum, (__u16 *)payload, len);
}
static void nfq_ip_set_checksum(struct iphdr *iph)
{
__u32 iph_len = iph->ihl * 4;
iph->check = 0;
iph->check = nfq_checksum(0, (__u16 *)iph, iph_len);
}
static void
nfq_tcp_compute_checksum_ipv4(struct tcphdr *tcph, struct iphdr *iph)
{
/* checksum field in header needs to be zero for calculation. */
tcph->check = 0;
tcph->check = nfq_checksum_tcpudp_ipv4(iph, IPPROTO_TCP);
}
#else
#include <stdio.h>
#include <libnetfilter_queue/libnetfilter_queue_ipv4.h>
#include <libnetfilter_queue/libnetfilter_queue_tcp.h>
typedef uint8_t __u8;
typedef uint32_t __u32;
typedef uint16_t __u16;
#endif
int ip4_payload_split(__u8 *pkt, __u32 buflen,
struct iphdr **iph, __u32 *iph_len,
__u8 **payload, __u32 *plen) {
if (pkt == NULL || buflen < sizeof(struct iphdr)) {
return -EINVAL;
}
struct iphdr *hdr = (struct iphdr *)pkt;
if (hdr->version != IPVERSION) return -EINVAL;
__u32 hdr_len = hdr->ihl * 4;
__u32 pktlen = ntohs(hdr->tot_len);
if (pktlen < buflen || hdr_len > pktlen) return -EINVAL;
if (iph)
*iph = hdr;
if (iph_len)
*iph_len = hdr_len;
if (payload)
*payload = pkt + hdr_len;
if (plen)
*plen = pktlen - hdr_len;
return 0;
}
int tcp4_payload_split(__u8 *pkt, __u32 buflen,
struct iphdr **iph, __u32 *iph_len,
struct tcphdr **tcph, __u32 *tcph_len,
__u8 **payload, __u32 *plen) {
struct iphdr *hdr;
__u32 hdr_len;
struct tcphdr *thdr;
__u32 thdr_len;
__u8 *tcph_pl;
__u32 tcph_plen;
if (ip4_payload_split(pkt, buflen, &hdr, &hdr_len,
&tcph_pl, &tcph_plen)){
return -EINVAL;
}
if (
hdr->protocol != IPPROTO_TCP ||
!(ntohs(hdr->frag_off) & IP_DF) ||
tcph_plen < sizeof(struct tcphdr)) {
return -EINVAL;
}
thdr = (struct tcphdr *)(tcph_pl);
thdr_len = (*tcph)->doff * 4;
if (thdr_len > tcph_plen) {
return -EINVAL;
}
if (iph) *iph = hdr;
if (iph_len) *iph_len = hdr_len;
if (tcph) *tcph = thdr;
if (tcph_len) *tcph_len = thdr_len;
if (payload) *payload = tcph_pl + thdr_len;
if (plen) *plen = tcph_plen - thdr_len;
return 0;
}
// split packet to two ipv4 fragments.
int ip4_frag(const __u8 *pkt, __u32 buflen, __u32 payload_offset,
__u8 *frag1, __u32 *f1len,
__u8 *frag2, __u32 *f2len) {
struct iphdr *hdr;
const __u8 *payload;
__u32 plen;
__u32 hdr_len;
if (ip4_payload_split(
(__u8 *)pkt, buflen,
&hdr, &hdr_len, (__u8 **)&payload, &plen)) {
return -EINVAL;
}
if (plen <= payload_offset) {
return -EINVAL;
}
if (payload_offset & ((1 << 3) - 1)) {
#ifdef KERNEL_SPACE
#else
errno = EINVAL;
perror("Payload offset MUST be a multiply of 8!");
#endif
return -EINVAL;
}
__u32 f1_plen = payload_offset;
__u32 f1_dlen = f1_plen + hdr_len;
__u32 f2_plen = plen - payload_offset;
__u32 f2_dlen = f2_plen + hdr_len;
if (*f1len < f1_dlen || *f2len < f2_dlen) {
return -ENOMEM;
}
*f1len = f1_dlen;
*f2len = f2_dlen;
memcpy(frag1, hdr, hdr_len);
memcpy(frag2, hdr, hdr_len);
memcpy(frag1 + hdr_len, payload, f1_plen);
memcpy(frag2 + hdr_len, payload + payload_offset, f2_plen);
struct iphdr *f1_hdr = (void *)frag1;
struct iphdr *f2_hdr = (void *)frag2;
__u16 f1_frag_off = ntohs(f1_hdr->frag_off);
__u16 f2_frag_off = ntohs(f2_hdr->frag_off);
f1_frag_off &= IP_OFFMASK;
f1_frag_off |= IP_MF;
if ((f2_frag_off & ~IP_OFFMASK) == IP_MF) {
f2_frag_off &= IP_OFFMASK;
f2_frag_off |= IP_MF;
} else {
f2_frag_off &= IP_OFFMASK;
}
f2_frag_off += (__u16)payload_offset / 8;
f1_hdr->frag_off = htons(f1_frag_off);
f1_hdr->tot_len = htons(f1_dlen);
f2_hdr->frag_off = htons(f2_frag_off);
f2_hdr->tot_len = htons(f2_dlen);
#if defined(DEBUG) && !defined(KERNEL_SPACE)
printf("Packet split in portion %u %u\n", f1_plen, f2_plen);
#endif
nfq_ip_set_checksum(f1_hdr);
nfq_ip_set_checksum(f2_hdr);
return 0;
}
// split packet to two tcp-on-ipv4 segments.
int tcp4_frag(const __u8 *pkt, __u32 buflen, __u32 payload_offset,
__u8 *seg1, __u32 *s1len,
__u8 *seg2, __u32 *s2len) {
struct iphdr *hdr;
__u32 hdr_len;
struct tcphdr *tcph;
__u32 tcph_len;
__u32 plen;
const __u8 *payload;
if (tcp4_payload_split((__u8 *)pkt, buflen,
&hdr, &hdr_len,
&tcph, &tcph_len,
(__u8 **)&payload, &plen)) {
return -EINVAL;
}
if (plen <= payload_offset) {
return -EINVAL;
}
__u32 s1_plen = payload_offset;
__u32 s1_dlen = s1_plen + hdr_len + tcph_len;
__u32 s2_plen = plen - payload_offset;
__u32 s2_dlen = s2_plen + hdr_len + tcph_len;
if (*s1len < s1_dlen || *s2len < s2_dlen) return -ENOMEM;
*s1len = s1_dlen;
*s2len = s2_dlen;
memcpy(seg1, hdr, hdr_len);
memcpy(seg2, hdr, hdr_len);
memcpy(seg1 + hdr_len, tcph, tcph_len);
memcpy(seg2 + hdr_len, tcph, tcph_len);
memcpy(seg1 + hdr_len + tcph_len, payload, s1_plen);
memcpy(seg2 + hdr_len + tcph_len, payload + payload_offset, s2_plen);
struct iphdr *s1_hdr = (void *)seg1;
struct iphdr *s2_hdr = (void *)seg2;
struct tcphdr *s1_tcph = (void *)(seg1 + hdr_len);
struct tcphdr *s2_tcph = (void *)(seg2 + hdr_len);
s1_hdr->tot_len = htons(s1_dlen);
s2_hdr->tot_len = htons(s2_dlen);
s2_tcph->seq = htonl(ntohl(s2_tcph->seq) + payload_offset);
#if defined(DEBUG) && !defined(KERNEL_SPACE)
printf("Packet split in portion %u %u\n", s1_plen, s2_plen);
#endif
nfq_tcp_compute_checksum_ipv4(s1_tcph, s1_hdr);
nfq_tcp_compute_checksum_ipv4(s2_tcph, s2_hdr);
return 0;
}
#define TLS_CONTENT_TYPE_HANDSHAKE 0x16
#define TLS_HANDSHAKE_TYPE_CLIENT_HELLO 0x01
#define TLS_EXTENSION_SNI 0x0000
#define TLS_EXTENSION_CLIENT_HELLO_ENCRYPTED 0xfe0d
const char googlevideo_ending[] = "googlevideo.com";
const int googlevideo_len = 15;
#define GOOGLEVIDEO_MARK 0xfc74
typedef __u8 uint8_t;
typedef __u32 uint32_t;
typedef __u16 uint16_t;
/**
* Processes tls payload of the tcp request.
*
* data Payload data of TCP.
* dlen Length of `data`.
*/
struct verdict analyze_tls_data(
const uint8_t *data,
uint32_t dlen)
{
struct verdict vrd = {0};
size_t i = 0;
const uint8_t *data_end = data + dlen;
while (i + 4 < dlen) {
const uint8_t *msgData = data + i;
uint8_t tls_content_type = *msgData;
uint8_t tls_vmajor = *(msgData + 1);
uint8_t tls_vminor = *(msgData + 2);
uint16_t message_length = ntohs(*(uint16_t *)(msgData + 3));
const uint8_t *message_length_ptr = msgData + 3;
if (i + 5 + message_length > dlen) break;
if (tls_content_type != TLS_CONTENT_TYPE_HANDSHAKE)
goto nextMessage;
const uint8_t *handshakeProto = msgData + 5;
if (handshakeProto + 1 >= data_end) break;
uint8_t handshakeType = *handshakeProto;
if (handshakeType != TLS_HANDSHAKE_TYPE_CLIENT_HELLO)
goto nextMessage;
const uint8_t *msgPtr = handshakeProto;
msgPtr += 1;
const uint8_t *handshakeProto_length_ptr = msgPtr + 1;
msgPtr += 3 + 2 + 32;
if (msgPtr + 1 >= data_end) break;
uint8_t sessionIdLength = *msgPtr;
msgPtr++;
msgPtr += sessionIdLength;
if (msgPtr + 2 >= data_end) break;
uint16_t ciphersLength = ntohs(*(uint16_t *)msgPtr);
msgPtr += 2;
msgPtr += ciphersLength;
if (msgPtr + 1 >= data_end) break;
uint8_t compMethodsLen = *msgPtr;
msgPtr++;
msgPtr += compMethodsLen;
if (msgPtr + 2 >= data_end) break;
uint16_t extensionsLen = ntohs(*(uint16_t *)msgPtr);
const uint8_t *extensionsLen_ptr = msgPtr;
msgPtr += 2;
const uint8_t *extensionsPtr = msgPtr;
const uint8_t *extensions_end = extensionsPtr + extensionsLen;
if (extensions_end > data_end) break;
while (extensionsPtr < extensions_end) {
const uint8_t *extensionPtr = extensionsPtr;
if (extensionPtr + 4 >= extensions_end) break;
uint16_t extensionType =
ntohs(*(uint16_t *)extensionPtr);
extensionPtr += 2;
uint16_t extensionLen =
ntohs(*(uint16_t *)extensionPtr);
const uint8_t *extensionLen_ptr = extensionPtr;
extensionPtr += 2;
if (extensionPtr + extensionLen > extensions_end)
break;
if (extensionType != TLS_EXTENSION_SNI)
goto nextExtension;
const uint8_t *sni_ext_ptr = extensionPtr;
if (sni_ext_ptr + 2 >= extensions_end) break;
uint16_t sni_ext_dlen = ntohs(*(uint16_t *)sni_ext_ptr);
const uint8_t *sni_ext_dlen_ptr = sni_ext_ptr;
sni_ext_ptr += 2;
const uint8_t *sni_ext_end = sni_ext_ptr + sni_ext_dlen;
if (sni_ext_end >= extensions_end) break;
if (sni_ext_ptr + 3 >= sni_ext_end) break;
uint8_t sni_type = *sni_ext_ptr++;
uint16_t sni_len = ntohs(*(uint16_t *)sni_ext_ptr);
sni_ext_ptr += 2;
if (sni_ext_ptr + sni_len > sni_ext_end) break;
char *sni_name = (char *)sni_ext_ptr;
// sni_len
vrd.sni_offset = (uint8_t *)sni_name - data;
vrd.sni_len = sni_len;
char *gv_startp = sni_name + sni_len - googlevideo_len;
if (sni_len >= googlevideo_len &&
sni_len < 128 &&
!strncmp(gv_startp,
googlevideo_ending,
googlevideo_len)) {
vrd.gvideo_hello = 1;
}
nextExtension:
extensionsPtr += 2 + 2 + extensionLen;
}
nextMessage:
i += 5 + message_length;
}
return vrd;
}

63
mangle.h Normal file
View File

@ -0,0 +1,63 @@
#ifndef YU_MANGLE_H
#define YU_MANGLE_H
#define RAWSOCKET_MARK 0xfc70
#ifdef KERNEL_SPACE
#include <linux/types.h>
typedef __u8 uint8_t;
typedef __u32 uint32_t;
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/stddef.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <asm/byteorder.h>
#define ntohs(x) __constant_ntohs(x)
#define ntohl(x) __constant_ntohl(x)
#define htons(x) __constant_htons(x)
#define htonl(x) __constant_htonl(x)
#define IP_RF 0x8000 /* reserved fragment flag */
#define IP_DF 0x4000 /* dont fragment flag */
#define IP_MF 0x2000 /* more fragments flag */
#define IP_OFFMASK 0x1fff /* mask for fragmenting bits */
#else
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#endif
struct verdict {
int gvideo_hello; /* google video hello packet */
int sni_offset; /* offset from start of tcp _payload_ */
int sni_len;
};
struct verdict analyze_tls_data(const uint8_t *data, uint32_t dlen);
int ip4_frag(const uint8_t *pkt, uint32_t pktlen,
uint32_t payload_offset,
uint8_t *frag1, uint32_t *f1len,
uint8_t *frag2, uint32_t *f2len);
int tcp4_frag(const uint8_t *pkt, uint32_t pktlen,
uint32_t payload_offset,
uint8_t *seg1, uint32_t *s1len,
uint8_t *seg2, uint32_t *s2len);
int ip4_payload_split(uint8_t *pkt, uint32_t buflen,
struct iphdr **iph, uint32_t *iph_len,
uint8_t **payload, uint32_t *plen);
int tcp4_payload_split(uint8_t *pkt, uint32_t buflen,
struct iphdr **iph, uint32_t *iph_len,
struct tcphdr **tcph, uint32_t *tcph_len,
uint8_t **payload, uint32_t *plen);
#endif /* YU_MANGLE_H */

View File

@ -1,10 +1,15 @@
#define _GNU_SOURCE #define _GNU_SOURCE
#ifndef __linux__
#error "The package is linux only!"
#endif
#ifdef KERNEL_SPACE
#error "The build aims to the kernel, not userspace"
#endif
#include <libnetfilter_queue/linux_nfnetlink_queue.h> #include <libnetfilter_queue/linux_nfnetlink_queue.h>
#include <stdio.h> #include <stdio.h>
#include <errno.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <libmnl/libmnl.h> #include <libmnl/libmnl.h>
#include <libnetfilter_queue/libnetfilter_queue.h> #include <libnetfilter_queue/libnetfilter_queue.h>
@ -21,6 +26,7 @@
#include <sys/socket.h> #include <sys/socket.h>
#include <pthread.h> #include <pthread.h>
#include "mangle.h"
#ifndef NOUSE_GSO #ifndef NOUSE_GSO
#define USE_GSO #define USE_GSO
@ -41,9 +47,6 @@
#error "Too much threads" #error "Too much threads"
#endif #endif
#ifndef __linux__
#error "The package is linux only!"
#endif
static struct { static struct {
uint32_t queue_start_num; uint32_t queue_start_num;
@ -173,229 +176,63 @@ static int close_raw_socket(void) {
return 0; return 0;
} }
// split packet to two ipv4 fragments.
static int ipv4_frag(struct pkt_buff *pktb, size_t payload_offset,
struct pkt_buff **frag1, struct pkt_buff **frag2) {
uint8_t buff1[MNL_SOCKET_BUFFER_SIZE];
uint8_t buff2[MNL_SOCKET_BUFFER_SIZE];
struct iphdr *hdr = nfq_ip_get_hdr(pktb);
size_t hdr_len = hdr->ihl * 4;
uint8_t *payload = pktb_data(pktb) + hdr_len;
size_t plen = pktb_len(pktb) - hdr_len;
if (hdr == NULL || payload == NULL || plen <= payload_offset) {
errno = EINVAL;
return -1;
}
if (payload_offset & ((1 << 3) - 1)) {
fprintf(stderr, "Payload offset MUST be a multiply of 8!\n");
errno = EINVAL;
return -1;
}
size_t f1_plen = payload_offset;
size_t f1_dlen = f1_plen + hdr_len;
size_t f2_plen = plen - payload_offset;
size_t f2_dlen = f2_plen + hdr_len;
memcpy(buff1, hdr, hdr_len);
memcpy(buff2, hdr, hdr_len);
memcpy(buff1 + hdr_len, payload, f1_plen);
memcpy(buff2 + hdr_len, payload + payload_offset, f2_plen);
struct iphdr *f1_hdr = (void *)buff1;
struct iphdr *f2_hdr = (void *)buff2;
uint16_t f1_frag_off = ntohs(f1_hdr->frag_off);
uint16_t f2_frag_off = ntohs(f2_hdr->frag_off);
f1_frag_off &= IP_OFFMASK;
f1_frag_off |= IP_MF;
if ((f2_frag_off & ~IP_OFFMASK) == IP_MF) {
f2_frag_off &= IP_OFFMASK;
f2_frag_off |= IP_MF;
} else {
f2_frag_off &= IP_OFFMASK;
}
f2_frag_off += (uint16_t)payload_offset / 8;
f1_hdr->frag_off = htons(f1_frag_off);
f1_hdr->tot_len = htons(f1_dlen);
f2_hdr->frag_off = htons(f2_frag_off);
f2_hdr->tot_len = htons(f2_dlen);
#ifdef DEBUG
printf("Packet split in portion %zu %zu\n", f1_dlen, f2_dlen);
#endif
nfq_ip_set_checksum(f1_hdr);
nfq_ip_set_checksum(f2_hdr);
*frag1 = pktb_alloc(AF_INET, buff1, f1_dlen, 0);
if (*frag1 == NULL)
return -1;
*frag2 = pktb_alloc(AF_INET, buff2, f2_dlen, 0);
if (*frag2 == NULL) {
pktb_free(*frag1);
return -1;
}
return 0;
}
// split packet to two tcp-on-ipv4 segments.
static int tcp4_frag(struct pkt_buff *pktb, size_t payload_offset,
struct pkt_buff **seg1, struct pkt_buff **seg2) {
uint8_t buff1[MNL_SOCKET_BUFFER_SIZE];
uint8_t buff2[MNL_SOCKET_BUFFER_SIZE];
struct iphdr *hdr = nfq_ip_get_hdr(pktb);
size_t hdr_len = hdr->ihl * 4;
if (hdr == NULL) {errno = EINVAL; return -1;}
if (hdr->protocol != IPPROTO_TCP || !(ntohs(hdr->frag_off) & IP_DF)) {
errno = EINVAL;
return -1;
}
if (nfq_ip_set_transport_header(pktb, hdr))
return -1;
struct tcphdr *tcph = nfq_tcp_get_hdr(pktb);
size_t tcph_len = tcph->doff * 4;
if (tcph == NULL) {
errno = EINVAL;
return -1;
}
uint8_t *payload = nfq_tcp_get_payload(tcph, pktb);
size_t plen = nfq_tcp_get_payload_len(tcph, pktb);
if (hdr == NULL || payload == NULL || plen <= payload_offset) {
errno = EINVAL;
return -1;
}
size_t s1_plen = payload_offset;
size_t s1_dlen = s1_plen + hdr_len + tcph_len;
size_t s2_plen = plen - payload_offset;
size_t s2_dlen = s2_plen + hdr_len + tcph_len;
memcpy(buff1, hdr, hdr_len);
memcpy(buff2, hdr, hdr_len);
memcpy(buff1 + hdr_len, tcph, tcph_len);
memcpy(buff2 + hdr_len, tcph, tcph_len);
memcpy(buff1 + hdr_len + tcph_len, payload, s1_plen);
memcpy(buff2 + hdr_len + tcph_len, payload + payload_offset, s2_plen);
struct iphdr *s1_hdr = (void *)buff1;
struct iphdr *s2_hdr = (void *)buff2;
struct tcphdr *s1_tcph = (void *)(buff1 + hdr_len);
struct tcphdr *s2_tcph = (void *)(buff2 + hdr_len);
s1_hdr->tot_len = htons(s1_dlen);
s2_hdr->tot_len = htons(s2_dlen);
// s2_hdr->id = htons(ntohs(s1_hdr->id) + 1);
s2_tcph->seq = htonl(ntohl(s2_tcph->seq) + payload_offset);
// printf("%zu %du %du\n", payload_offset, ntohs(s1_tcph->seq), ntohs(s2_tcph->seq));
#ifdef DEBUG
printf("Packet split in portion %zu %zu\n", s1_dlen, s2_dlen);
#endif
nfq_tcp_compute_checksum_ipv4(s1_tcph, s1_hdr);
nfq_tcp_compute_checksum_ipv4(s2_tcph, s2_hdr);
*seg1 = pktb_alloc(AF_INET, buff1, s1_dlen, 0);
if (*seg1 == NULL)
return -1;
*seg2 = pktb_alloc(AF_INET, buff2, s2_dlen, 0);
if (*seg2 == NULL) {
pktb_free(*seg1);
return -1;
}
return 0;
}
#define AVAILABLE_MTU 1384 #define AVAILABLE_MTU 1384
static int send_raw_socket(struct pkt_buff *pktb) { static int send_raw_socket(const uint8_t *pkt, uint32_t pktlen) {
if (pktb_len(pktb) > AVAILABLE_MTU) { if (pktlen > AVAILABLE_MTU) {
#ifdef DEBUG #ifdef DEBUG
printf("Split packet!\n"); printf("Split packet!\n");
#endif #endif
struct pkt_buff *buff1; uint8_t buff1[MNL_SOCKET_BUFFER_SIZE];
struct pkt_buff *buff2; uint32_t buff1_size = MNL_SOCKET_BUFFER_SIZE;
uint8_t buff2[MNL_SOCKET_BUFFER_SIZE];
uint32_t buff2_size = MNL_SOCKET_BUFFER_SIZE;
#ifdef USE_TCP_SEGMENTATION #ifdef USE_TCP_SEGMENTATION
if (tcp4_frag(pktb, AVAILABLE_MTU-128, &buff1, &buff2) < 0) if ((errno = tcp4_frag(pkt, pktlen, AVAILABLE_MTU-128,
buff1, &buff1_size, buff2, &buff2_size)) < 0)
return -1; return -1;
#else #else
if (ipv4_frag(pktb, AVAILABLE_MTU-128, &buff1, &buff2) < 0) if ((errno = ip4_frag(pkt, pktlen, AVAILABLE_MTU-128,
buff1, &buff1_size, buff2, &buff2_size)) < 0)
return -1; return -1;
#endif #endif
int sent = 0; int sent = 0;
int status = send_raw_socket(buff1); int status = send_raw_socket(buff1, buff1_size);
if (status >= 0) sent += status; if (status >= 0) sent += status;
else { else {
pktb_free(buff1);
pktb_free(buff2);
return status; return status;
} }
pktb_free(buff1);
status = send_raw_socket(buff2); status = send_raw_socket(buff2, buff2_size);
if (status >= 0) sent += status; if (status >= 0) sent += status;
else { else {
pktb_free(buff2);
return status; return status;
} }
pktb_free(buff2);
return sent; return sent;
} }
struct iphdr *iph = nfq_ip_get_hdr(pktb);
if (iph == NULL)
return -1;
if(nfq_ip_set_transport_header(pktb, iph)) struct iphdr *iph;
if ((errno = ip4_payload_split(
(uint8_t *)pkt, pktlen, &iph, NULL, NULL, NULL)) < 0) {
errno *= -1;
return -1; return -1;
}
int sin_port = 0; int sin_port = 0;
struct tcphdr *tcph = nfq_tcp_get_hdr(pktb); struct tcphdr *tcph;
struct udphdr *udph = nfq_udp_get_hdr(pktb); if (tcp4_payload_split((uint8_t *)pkt, pktlen, NULL, NULL, &tcph, NULL, NULL, NULL) == 0)
if (tcph != NULL) {
sin_port = tcph->dest; sin_port = tcph->dest;
errno = 0;
} else if (udph != NULL) {
sin_port = udph->dest;
} else {
return -1;
}
struct sockaddr_in daddr = { struct sockaddr_in daddr = {
.sin_family = AF_INET, .sin_family = AF_INET,
@ -408,7 +245,7 @@ static int send_raw_socket(struct pkt_buff *pktb) {
pthread_mutex_lock(&config.rawsocket_lock); pthread_mutex_lock(&config.rawsocket_lock);
int sent = sendto(config.rawsocket, int sent = sendto(config.rawsocket,
pktb_data(pktb), pktb_len(pktb), 0, pkt, pktlen, 0,
(struct sockaddr *)&daddr, sizeof(daddr)); (struct sockaddr *)&daddr, sizeof(daddr));
pthread_mutex_unlock(&config.rawsocket_lock); pthread_mutex_unlock(&config.rawsocket_lock);
@ -426,160 +263,13 @@ struct packet_data {
}; };
#define TLS_CONTENT_TYPE_HANDSHAKE 0x16
#define TLS_HANDSHAKE_TYPE_CLIENT_HELLO 0x01
#define TLS_EXTENSION_SNI 0x0000
#define TLS_EXTENSION_CLIENT_HELLO_ENCRYPTED 0xfe0d
const char googlevideo_ending[] = "googlevideo.com";
const int googlevideo_len = 15;
#define GOOGLEVIDEO_MARK 0xfc74
struct verdict {
int gvideo_hello; /* google video hello packet */
int sni_offset; /* offset from start of tcp _payload_ */
int sni_len;
};
/**
* Processes tls payload of the tcp request.
*
* data Payload data of TCP.
* dlen Length of `data`.
*/
static struct verdict analyze_tls_data(
const uint8_t *data,
uint32_t dlen)
{
struct verdict vrd = {0};
size_t i = 0;
const uint8_t *data_end = data + dlen;
while (i + 4 < dlen) {
const uint8_t *msgData = data + i;
uint8_t tls_content_type = *msgData;
uint8_t tls_vmajor = *(msgData + 1);
uint8_t tls_vminor = *(msgData + 2);
uint16_t message_length = ntohs(*(uint16_t *)(msgData + 3));
const uint8_t *message_length_ptr = msgData + 3;
if (i + 5 + message_length > dlen) break;
if (tls_content_type != TLS_CONTENT_TYPE_HANDSHAKE)
goto nextMessage;
const uint8_t *handshakeProto = msgData + 5;
if (handshakeProto + 1 >= data_end) break;
uint8_t handshakeType = *handshakeProto;
if (handshakeType != TLS_HANDSHAKE_TYPE_CLIENT_HELLO)
goto nextMessage;
const uint8_t *msgPtr = handshakeProto;
msgPtr += 1;
const uint8_t *handshakeProto_length_ptr = msgPtr + 1;
msgPtr += 3 + 2 + 32;
if (msgPtr + 1 >= data_end) break;
uint8_t sessionIdLength = *msgPtr;
msgPtr++;
msgPtr += sessionIdLength;
if (msgPtr + 2 >= data_end) break;
uint16_t ciphersLength = ntohs(*(uint16_t *)msgPtr);
msgPtr += 2;
msgPtr += ciphersLength;
if (msgPtr + 1 >= data_end) break;
uint8_t compMethodsLen = *msgPtr;
msgPtr++;
msgPtr += compMethodsLen;
if (msgPtr + 2 >= data_end) break;
uint16_t extensionsLen = ntohs(*(uint16_t *)msgPtr);
const uint8_t *extensionsLen_ptr = msgPtr;
msgPtr += 2;
const uint8_t *extensionsPtr = msgPtr;
const uint8_t *extensions_end = extensionsPtr + extensionsLen;
if (extensions_end > data_end) break;
while (extensionsPtr < extensions_end) {
const uint8_t *extensionPtr = extensionsPtr;
if (extensionPtr + 4 >= extensions_end) break;
uint16_t extensionType =
ntohs(*(uint16_t *)extensionPtr);
extensionPtr += 2;
uint16_t extensionLen =
ntohs(*(uint16_t *)extensionPtr);
const uint8_t *extensionLen_ptr = extensionPtr;
extensionPtr += 2;
if (extensionPtr + extensionLen > extensions_end)
break;
if (extensionType != TLS_EXTENSION_SNI)
goto nextExtension;
const uint8_t *sni_ext_ptr = extensionPtr;
if (sni_ext_ptr + 2 >= extensions_end) break;
uint16_t sni_ext_dlen = ntohs(*(uint16_t *)sni_ext_ptr);
const uint8_t *sni_ext_dlen_ptr = sni_ext_ptr;
sni_ext_ptr += 2;
const uint8_t *sni_ext_end = sni_ext_ptr + sni_ext_dlen;
if (sni_ext_end >= extensions_end) break;
if (sni_ext_ptr + 3 >= sni_ext_end) break;
uint8_t sni_type = *sni_ext_ptr++;
uint16_t sni_len = ntohs(*(uint16_t *)sni_ext_ptr);
sni_ext_ptr += 2;
if (sni_ext_ptr + sni_len > sni_ext_end) break;
char *sni_name = (char *)sni_ext_ptr;
// sni_len
vrd.sni_offset = (uint8_t *)sni_name - data;
vrd.sni_len = sni_len;
char *gv_startp = sni_name + sni_len - googlevideo_len;
if (sni_len >= googlevideo_len &&
sni_len < 128 &&
!strncmp(gv_startp,
googlevideo_ending,
googlevideo_len)) {
vrd.gvideo_hello = 1;
}
nextExtension:
extensionsPtr += 2 + 2 + extensionLen;
}
nextMessage:
i += 5 + message_length;
}
return vrd;
}
// Per-queue data. Passed to queue_cb. // Per-queue data. Passed to queue_cb.
struct queue_data { struct queue_data {
struct mnl_socket **_nl; struct mnl_socket **_nl;
int queue_num; int queue_num;
}; };
/** /**
* Used to accept unsupported packets (GSOs) * Used to accept unsupported packets (GSOs)
*/ */
@ -655,8 +345,10 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
#endif #endif
} }
struct pkt_buff *frag1; uint8_t frag1[MNL_SOCKET_BUFFER_SIZE];
struct pkt_buff *frag2; uint8_t frag2[MNL_SOCKET_BUFFER_SIZE];
uint32_t f1len = MNL_SOCKET_BUFFER_SIZE;
uint32_t f2len = MNL_SOCKET_BUFFER_SIZE;
nfq_nlmsg_verdict_put(verdnlh, packet.id, NF_DROP); nfq_nlmsg_verdict_put(verdnlh, packet.id, NF_DROP);
@ -664,26 +356,18 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
size_t ipd_offset = vrd.sni_offset; size_t ipd_offset = vrd.sni_offset;
size_t mid_offset = ipd_offset + vrd.sni_len / 2; size_t mid_offset = ipd_offset + vrd.sni_len / 2;
struct pkt_buff *pktb = pktb_alloc( if ((errno = tcp4_frag(raw_payload, raw_payload_len,
family, mid_offset, frag1, &f1len, frag2, &f2len)) < 0) {
packet.payload, errno *= -1;
packet.payload_len,
0);
if (tcp4_frag(pktb, mid_offset, &frag1, &frag2) < 0) {
perror("tcp4_frag"); perror("tcp4_frag");
pktb_free(pktb);
goto fallback; goto fallback;
} }
if ((send_raw_socket(frag2) == -1) || (send_raw_socket(frag1) == -1)) { if ((send_raw_socket(frag2, f2len) < 0) ||
(send_raw_socket(frag1, f1len) < 0)) {
perror("raw frags send"); perror("raw frags send");
} }
pktb_free(frag1);
pktb_free(frag2);
pktb_free(pktb);
#else #else
// TODO: Implement compute of tcp checksum // TODO: Implement compute of tcp checksum
// GSO may turn kernel to not compute the tcp checksum. // GSO may turn kernel to not compute the tcp checksum.
@ -694,19 +378,19 @@ static int process_packet(const struct packet_data packet, struct queue_data qda
size_t ipd_offset = ((char *)data - (char *)tcph) + vrd.sni_offset; size_t ipd_offset = ((char *)data - (char *)tcph) + vrd.sni_offset;
size_t mid_offset = ipd_offset + vrd.sni_len / 2; size_t mid_offset = ipd_offset + vrd.sni_len / 2;
mid_offset += 8 - mid_offset % 8; mid_offset += 8 - mid_offset % 8;
if (ipv4_frag(pktb, mid_offset, &frag1, &frag2) < 0) { if ((errno = ip4_frag(raw_payload, raw_payload_len,
perror("ipv4_frag"); mid_offset, frag1, &f1len, frag2, &f2len)) < 0) {
errno *= -1;
perror("ip4_frag");
goto fallback; goto fallback;
} }
if ((send_raw_socket(frag1) == -1) || (send_raw_socket(frag2) == -1)) { if ((send_raw_socket(frag2, f2len) < 0) ||
(send_raw_socket(frag1, f1len) < 0)) {
perror("raw frags send"); perror("raw frags send");
} }
pktb_free(frag1);
pktb_free(frag2);
#endif #endif
} }
@ -780,6 +464,8 @@ static int queue_cb(const struct nlmsghdr *nlh, void *data) {
return process_packet(packet, *qdata); return process_packet(packet, *qdata);
} }
#define BUF_SIZE (0xffff + (MNL_SOCKET_BUFFER_SIZE / 2))
int init_queue(int queue_num) { int init_queue(int queue_num) {
struct mnl_socket *nl; struct mnl_socket *nl;
@ -791,14 +477,7 @@ int init_queue(int queue_num) {
uint32_t portid = mnl_socket_get_portid(nl); uint32_t portid = mnl_socket_get_portid(nl);
struct nlmsghdr *nlh; struct nlmsghdr *nlh;
char *buf; char buf[BUF_SIZE];
size_t buf_size = 0xffff + (MNL_SOCKET_BUFFER_SIZE / 2);
buf = malloc(buf_size);
if (!buf) {
perror("Allocate recieve buffer");
goto die_sock;
}
nlh = nfq_nlmsg_put(buf, NFQNL_MSG_CONFIG, queue_num); nlh = nfq_nlmsg_put(buf, NFQNL_MSG_CONFIG, queue_num);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_BIND); nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_BIND);
@ -837,7 +516,7 @@ int init_queue(int queue_num) {
printf("Queue %d started!\n", qdata.queue_num); printf("Queue %d started!\n", qdata.queue_num);
while (1) { while (1) {
ret = mnl_socket_recvfrom(nl, buf, buf_size); ret = mnl_socket_recvfrom(nl, buf, BUF_SIZE);
if (ret == -1) { if (ret == -1) {
perror("mnl_socket_recvfrom"); perror("mnl_socket_recvfrom");
continue; continue;
@ -850,13 +529,10 @@ int init_queue(int queue_num) {
} }
free(buf);
close_socket(&nl); close_socket(&nl);
return 0; return 0;
die: die:
free(buf);
die_sock:
close_socket(&nl); close_socket(&nl);
return -1; return -1;
} }