zapret/tpws/tamper.c

528 lines
17 KiB
C

#define _GNU_SOURCE
#include <string.h>
#include <stdio.h>
#include "tamper.h"
#include "hostlist.h"
#include "ipset.h"
#include "protocol.h"
#include "helpers.h"
const char *l7proto_str(t_l7proto l7)
{
switch(l7)
{
case HTTP: return "http";
case TLS: return "tls";
default: return "unknown";
}
}
static bool l7_proto_match(t_l7proto l7proto, uint32_t filter_l7)
{
return (l7proto==UNKNOWN && (filter_l7 & L7_PROTO_UNKNOWN)) ||
(l7proto==HTTP && (filter_l7 & L7_PROTO_HTTP)) ||
(l7proto==TLS && (filter_l7 & L7_PROTO_TLS));
}
static bool dp_match(struct desync_profile *dp, const struct sockaddr *dest, const char *hostname, t_l7proto l7proto)
{
bool bHostlistsEmpty;
if (!HostlistsReloadCheckForProfile(dp)) return false;
if ((dest->sa_family==AF_INET && !dp->filter_ipv4) || (dest->sa_family==AF_INET6 && !dp->filter_ipv6))
// L3 filter does not match
return false;
if (!port_filters_in_range(&dp->pf_tcp,saport(dest)))
// L4 filter does not match
return false;
if (dp->filter_l7 && !l7_proto_match(l7proto, dp->filter_l7))
// L7 filter does not match
return false;
bHostlistsEmpty = PROFILE_HOSTLISTS_EMPTY(dp);
if (!dp->hostlist_auto && !hostname && !bHostlistsEmpty)
// avoid cpu consuming ipset check. profile cannot win if regular hostlists are present without auto hostlist and hostname is unknown.
return false;
if (!IpsetCheck(dp, dest->sa_family==AF_INET ? &((struct sockaddr_in*)dest)->sin_addr : NULL, dest->sa_family==AF_INET6 ? &((struct sockaddr_in6*)dest)->sin6_addr : NULL))
// target ip does not match
return false;
// autohostlist profile matching l3/l4/l7 filter always win
if (dp->hostlist_auto) return true;
if (bHostlistsEmpty)
// profile without hostlist filter wins
return true;
else if (hostname)
// if hostlists are present profile matches only if hostname is known and satisfy profile hostlists
return HostlistCheck(dp, hostname, NULL, true);
return false;
}
static struct desync_profile *dp_find(struct desync_profile_list_head *head, const struct sockaddr *dest, const char *hostname, t_l7proto l7proto)
{
struct desync_profile_list *dpl;
if (params.debug)
{
char ip_port[48];
ntop46_port(dest, ip_port,sizeof(ip_port));
VPRINT("desync profile search for tcp target=%s l7proto=%s hostname='%s'\n", ip_port, l7proto_str(l7proto), hostname ? hostname : "");
}
LIST_FOREACH(dpl, head, next)
{
if (dp_match(&dpl->dp,dest,hostname,l7proto))
{
VPRINT("desync profile %d matches\n",dpl->dp.n);
return &dpl->dp;
}
}
VPRINT("desync profile not found\n");
return NULL;
}
void apply_desync_profile(t_ctrack *ctrack, const struct sockaddr *dest)
{
ctrack->dp = dp_find(&params.desync_profiles, dest, ctrack->hostname, ctrack->l7proto);
}
// segment buffer has at least 5 extra bytes to extend data block
void tamper_out(t_ctrack *ctrack, const struct sockaddr *dest, uint8_t *segment,size_t segment_buffer_size,size_t *size, size_t *split_pos, uint8_t *split_flags)
{
uint8_t *p, *pp, *pHost = NULL;
size_t method_len = 0, pos;
size_t tpos, spos;
const char *method;
bool bHaveHost = false;
char *pc, Host[256];
t_l7proto l7proto;
DBGPRINT("tamper_out\n");
if (!ctrack->dp) return;
if (params.debug)
{
char ip_port[48];
ntop46_port(dest,ip_port,sizeof(ip_port));
VPRINT("tampering tcp segment with size %zu to %s\n", *size, ip_port);
if (ctrack->dp) VPRINT("using cached desync profile %d\n",ctrack->dp->n);
if (ctrack->hostname) VPRINT("connection hostname: %s\n", ctrack->hostname);
}
if (dest->sa_family!=AF_INET && dest->sa_family!=AF_INET6)
{
DLOG_ERR("tamper_out dest family unknown\n");
return;
}
*split_pos=0;
*split_flags=0;
if ((method = HttpMethod(segment,*size)))
{
method_len = strlen(method)-2;
VPRINT("Data block looks like http request start : %s\n", method);
l7proto=HTTP;
if (HttpFindHost(&pHost,segment,*size))
{
p = pHost + 5;
while (p < (segment + *size) && (*p == ' ' || *p == '\t')) p++;
pp = p;
while (pp < (segment + *size) && (pp - p) < (sizeof(Host) - 1) && *pp != '\r' && *pp != '\n') pp++;
memcpy(Host, p, pp - p);
Host[pp - p] = '\0';
bHaveHost = true;
for(pc = Host; *pc; pc++) *pc=tolower(*pc);
}
}
else if (IsTLSClientHello(segment,*size,false))
{
VPRINT("Data block contains TLS ClientHello\n");
l7proto=TLS;
bHaveHost=TLSHelloExtractHost((uint8_t*)segment,*size,Host,sizeof(Host),false);
}
else
{
VPRINT("Data block contains unknown payload\n");
l7proto = UNKNOWN;
}
if (bHaveHost)
VPRINT("request hostname: %s\n", Host);
if (ctrack->b_not_act)
{
VPRINT("Not acting on this request\n");
return;
}
bool bDiscoveredL7 = ctrack->l7proto==UNKNOWN && l7proto!=UNKNOWN;
if (bDiscoveredL7)
{
VPRINT("discovered l7 protocol\n");
ctrack->l7proto=l7proto;
}
bool bDiscoveredHostname = bHaveHost && !ctrack->hostname;
if (bDiscoveredHostname)
{
VPRINT("discovered hostname\n");
if (!(ctrack->hostname=strdup(Host)))
{
DLOG_ERR("strdup hostname : out of memory\n");
return;
}
}
if (bDiscoveredL7 || bDiscoveredHostname)
{
struct desync_profile *dp_prev = ctrack->dp;
apply_desync_profile(ctrack, dest);
if (ctrack->dp!=dp_prev)
VPRINT("desync profile changed by revealed l7 protocol or hostname !\n");
}
if (bDiscoveredHostname && ctrack->dp->hostlist_auto)
{
bool bHostExcluded;
if (!HostlistCheck(ctrack->dp, Host, &bHostExcluded, false))
{
ctrack->b_ah_check = !bHostExcluded;
VPRINT("Not acting on this request\n");
ctrack->b_not_act = true;
return;
}
}
switch(l7proto)
{
case HTTP:
if (ctrack->dp->unixeol)
{
p = pp = segment;
while ((p = memmem(p, segment + *size - p, "\r\n", 2)))
{
*p = '\n'; p++;
memmove(p, p + 1, segment + *size - p - 1);
(*size)--;
if (pp == (p - 1))
{
// probably end of http headers
VPRINT("Found double EOL at pos %td. Stop replacing.\n", pp - segment);
break;
}
pp = p;
}
pHost = NULL; // invalidate
}
if (ctrack->dp->methodeol && (*size+1+!ctrack->dp->unixeol)<=segment_buffer_size)
{
VPRINT("Adding EOL before method\n");
if (ctrack->dp->unixeol)
{
memmove(segment + 1, segment, *size);
(*size)++;;
segment[0] = '\n';
}
else
{
memmove(segment + 2, segment, *size);
*size += 2;
segment[0] = '\r';
segment[1] = '\n';
}
pHost = NULL; // invalidate
}
if (ctrack->dp->methodspace && *size<segment_buffer_size)
{
// we only work with data blocks looking as HTTP query, so method is at the beginning
VPRINT("Adding extra space after method\n");
p = segment + method_len + 1;
pos = method_len + 1;
memmove(p + 1, p, *size - pos);
*p = ' '; // insert extra space
(*size)++; // block will grow by 1 byte
if (pHost) pHost++; // Host: position will move by 1 byte
}
if ((ctrack->dp->hostdot || ctrack->dp->hosttab) && *size<segment_buffer_size && HttpFindHost(&pHost,segment,*size))
{
p = pHost + 5;
while (p < (segment + *size) && *p != '\r' && *p != '\n') p++;
if (p < (segment + *size))
{
pos = p - segment;
VPRINT("Adding %s to host name at pos %zu\n", ctrack->dp->hostdot ? "dot" : "tab", pos);
memmove(p + 1, p, *size - pos);
*p = ctrack->dp->hostdot ? '.' : '\t'; // insert dot or tab
(*size)++; // block will grow by 1 byte
}
}
if (ctrack->dp->domcase && HttpFindHost(&pHost,segment,*size))
{
p = pHost + 5;
pos = p - segment;
VPRINT("Mixing domain case at pos %zu\n",pos);
for (; p < (segment + *size) && *p != '\r' && *p != '\n'; p++)
*p = (((size_t)p) & 1) ? tolower(*p) : toupper(*p);
}
if (ctrack->dp->hostnospace && HttpFindHost(&pHost,segment,*size) && (pHost+5)<(segment+*size) && pHost[5] == ' ')
{
p = pHost + 6;
pos = p - segment;
VPRINT("Removing space before host name at pos %zu\n", pos);
memmove(p - 1, p, *size - pos);
(*size)--; // block will shrink by 1 byte
}
if (ctrack->dp->hostcase && HttpFindHost(&pHost,segment,*size))
{
VPRINT("Changing 'Host:' => '%c%c%c%c:' at pos %td\n", ctrack->dp->hostspell[0], ctrack->dp->hostspell[1], ctrack->dp->hostspell[2], ctrack->dp->hostspell[3], pHost - segment);
memcpy(pHost, ctrack->dp->hostspell, 4);
}
if (ctrack->dp->hostpad && HttpFindHost(&pHost,segment,*size))
{
// add : XXXXX: <padding?[\r\n|\n]
char s[8];
size_t hsize = ctrack->dp->unixeol ? 8 : 9;
size_t hostpad = ctrack->dp->hostpad<hsize ? hsize : ctrack->dp->hostpad;
if ((hsize+*size)>segment_buffer_size)
VPRINT("could not add host padding : buffer too small\n");
else
{
if ((hostpad+*size)>segment_buffer_size)
{
hostpad=segment_buffer_size-*size;
VPRINT("host padding reduced to %zu bytes : buffer too small\n", hostpad);
}
else
VPRINT("host padding with %zu bytes\n", hostpad);
p = pHost;
pos = p - segment;
memmove(p + hostpad, p, *size - pos);
(*size) += hostpad;
while(hostpad)
{
#define MAX_HDR_SIZE 2048
size_t padsize = hostpad > hsize ? hostpad-hsize : 0;
if (padsize>MAX_HDR_SIZE) padsize=MAX_HDR_SIZE;
// if next header would be too small then add extra padding to the current one
if ((hostpad-padsize-hsize)<hsize) padsize+=hostpad-padsize-hsize;
snprintf(s,sizeof(s),"%c%04x: ", 'a'+rand()%('z'-'a'+1), rand() & 0xFFFF);
memcpy(p,s,7);
p+=7;
memset(p,'a'+rand()%('z'-'a'+1),padsize);
p+=padsize;
if (ctrack->dp->unixeol)
*p++='\n';
else
{
*p++='\r';
*p++='\n';
}
hostpad-=hsize+padsize;
}
pHost = NULL; // invalidate
}
}
*split_pos = HttpPos(ctrack->dp->split_http_req, ctrack->dp->split_pos, segment, *size);
if (ctrack->dp->disorder_http) *split_flags |= SPLIT_FLAG_DISORDER;
if (ctrack->dp->oob_http) *split_flags |= SPLIT_FLAG_OOB;
break;
case TLS:
spos = TLSPos(ctrack->dp->split_tls, ctrack->dp->split_pos, segment, *size, 0);
if ((5+*size)<=segment_buffer_size)
{
tpos = TLSPos(ctrack->dp->tlsrec, ctrack->dp->tlsrec_pos+5, segment, *size, 0);
if (tpos>5)
{
// construct 2 TLS records from one
uint16_t l = pntoh16(segment+3); // length
if (l>=2)
{
// length is checked in IsTLSClientHello and cannot exceed buffer size
if ((tpos-5)>=l) tpos=5+1;
VPRINT("making 2 TLS records at pos %zu\n",tpos);
memmove(segment+tpos+5,segment+tpos,*size-tpos);
segment[tpos] = segment[0];
segment[tpos+1] = segment[1];
segment[tpos+2] = segment[2];
phton16(segment+tpos+3,l-(tpos-5));
phton16(segment+3,tpos-5);
*size += 5;
// split pos present and it is not before tlsrec split. increase split pos by tlsrec header size (5 bytes)
if (spos && spos>=tpos) spos+=5;
}
}
}
if (spos && spos < *size)
*split_pos = spos;
if (ctrack->dp->disorder_tls) *split_flags |= SPLIT_FLAG_DISORDER;
if (ctrack->dp->oob_tls) *split_flags |= SPLIT_FLAG_OOB;
break;
default:
if (ctrack->dp->split_any_protocol && ctrack->dp->split_pos < *size)
*split_pos = ctrack->dp->split_pos;
}
if (ctrack->dp->disorder) *split_flags |= SPLIT_FLAG_DISORDER;
if (ctrack->dp->oob) *split_flags |= SPLIT_FLAG_OOB;
}
static void auto_hostlist_reset_fail_counter(struct desync_profile *dp, const char *hostname, const char *client_ip_port, t_l7proto l7proto)
{
if (hostname)
{
hostfail_pool *fail_counter;
fail_counter = HostFailPoolFind(dp->hostlist_auto_fail_counters, hostname);
if (fail_counter)
{
HostFailPoolDel(&dp->hostlist_auto_fail_counters, fail_counter);
VPRINT("auto hostlist (profile %d) : %s : fail counter reset. website is working.\n", dp->n, hostname);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : fail counter reset. website is working.", hostname, dp->n, client_ip_port, l7proto_str(l7proto));
}
}
}
static void auto_hostlist_failed(struct desync_profile *dp, const char *hostname, const char *client_ip_port, t_l7proto l7proto)
{
hostfail_pool *fail_counter;
fail_counter = HostFailPoolFind(dp->hostlist_auto_fail_counters, hostname);
if (!fail_counter)
{
fail_counter = HostFailPoolAdd(&dp->hostlist_auto_fail_counters, hostname, dp->hostlist_auto_fail_time);
if (!fail_counter)
{
DLOG_ERR("HostFailPoolAdd: out of memory\n");
return;
}
}
fail_counter->counter++;
VPRINT("auto hostlist (profile %d) : %s : fail counter %d/%d\n", dp->n , hostname, fail_counter->counter, dp->hostlist_auto_fail_threshold);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : fail counter %d/%d", hostname, dp->n, client_ip_port, l7proto_str(l7proto), fail_counter->counter, dp->hostlist_auto_fail_threshold);
if (fail_counter->counter >= dp->hostlist_auto_fail_threshold)
{
VPRINT("auto hostlist (profile %d) : fail threshold reached. adding %s to auto hostlist\n", dp->n , hostname);
HostFailPoolDel(&dp->hostlist_auto_fail_counters, fail_counter);
VPRINT("auto hostlist (profile %d) : rechecking %s to avoid duplicates\n", dp->n, hostname);
bool bExcluded=false;
if (!HostlistCheck(dp, hostname, &bExcluded, false) && !bExcluded)
{
VPRINT("auto hostlist (profile %d) : adding %s to %s\n", dp->n, hostname, dp->hostlist_auto->filename);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : adding to %s", hostname, dp->n, client_ip_port, l7proto_str(l7proto), dp->hostlist_auto->filename);
if (!StrPoolAddStr(&dp->hostlist_auto->hostlist, hostname))
{
DLOG_ERR("StrPoolAddStr out of memory\n");
return;
}
if (!append_to_list_file(dp->hostlist_auto->filename, hostname))
{
DLOG_PERROR("write to auto hostlist:");
return;
}
dp->hostlist_auto->mod_time = file_mod_time(dp->hostlist_auto->filename);
}
else
{
VPRINT("auto hostlist (profile %d) : NOT adding %s\n", dp->n, hostname);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : NOT adding, duplicate detected", hostname, dp->n, client_ip_port, l7proto_str(l7proto));
}
}
}
void tamper_in(t_ctrack *ctrack, const struct sockaddr *client, uint8_t *segment,size_t segment_buffer_size,size_t *size)
{
DBGPRINT("tamper_in hostname=%s\n", ctrack->hostname);
bool bFail=false;
char client_ip_port[48];
if (*params.hostlist_auto_debuglog)
ntop46_port((struct sockaddr*)client,client_ip_port,sizeof(client_ip_port));
else
*client_ip_port=0;
if (ctrack->dp && ctrack->b_ah_check)
{
HostFailPoolPurgeRateLimited(&ctrack->dp->hostlist_auto_fail_counters);
if (ctrack->l7proto==HTTP && ctrack->hostname)
{
if (IsHttpReply(segment,*size))
{
VPRINT("incoming HTTP reply detected for hostname %s\n", ctrack->hostname);
bFail = HttpReplyLooksLikeDPIRedirect(segment, *size, ctrack->hostname);
if (bFail)
{
VPRINT("redirect to another domain detected. possibly DPI redirect.\n");
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : redirect to another domain", ctrack->hostname, ctrack->dp->n, client_ip_port, l7proto_str(ctrack->l7proto));
}
else
VPRINT("local or in-domain redirect detected. it's not a DPI redirect.\n");
}
else
{
// received not http reply. do not monitor this connection anymore
VPRINT("incoming unknown HTTP data detected for hostname %s\n", ctrack->hostname);
}
if (bFail) auto_hostlist_failed(ctrack->dp, ctrack->hostname, client_ip_port, ctrack->l7proto);
}
if (!bFail) auto_hostlist_reset_fail_counter(ctrack->dp, ctrack->hostname, client_ip_port, ctrack->l7proto);
}
ctrack->bTamperInCutoff = true;
}
void rst_in(t_ctrack *ctrack, const struct sockaddr *client)
{
DBGPRINT("rst_in hostname=%s\n", ctrack->hostname);
char client_ip_port[48];
if (*params.hostlist_auto_debuglog)
ntop46_port((struct sockaddr*)client,client_ip_port,sizeof(client_ip_port));
else
*client_ip_port=0;
if (ctrack->dp && ctrack->b_ah_check)
{
HostFailPoolPurgeRateLimited(&ctrack->dp->hostlist_auto_fail_counters);
if (!ctrack->bTamperInCutoff && ctrack->hostname)
{
VPRINT("incoming RST detected for hostname %s\n", ctrack->hostname);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : incoming RST", ctrack->hostname, ctrack->dp->n, client_ip_port, l7proto_str(ctrack->l7proto));
auto_hostlist_failed(ctrack->dp, ctrack->hostname, client_ip_port, ctrack->l7proto);
}
}
}
void hup_out(t_ctrack *ctrack, const struct sockaddr *client)
{
DBGPRINT("hup_out hostname=%s\n", ctrack->hostname);
char client_ip_port[48];
if (*params.hostlist_auto_debuglog)
ntop46_port((struct sockaddr*)client,client_ip_port,sizeof(client_ip_port));
else
*client_ip_port=0;
if (ctrack->dp && ctrack->b_ah_check)
{
HostFailPoolPurgeRateLimited(&ctrack->dp->hostlist_auto_fail_counters);
if (!ctrack->bTamperInCutoff && ctrack->hostname)
{
// local leg dropped connection after first request. probably due to timeout.
VPRINT("local leg closed connection after first request (timeout ?). hostname: %s\n", ctrack->hostname);
HOSTLIST_DEBUGLOG_APPEND("%s : profile %d : client %s : proto %s : client closed connection without server reply", ctrack->hostname, ctrack->dp->n, client_ip_port, l7proto_str(ctrack->l7proto));
auto_hostlist_failed(ctrack->dp, ctrack->hostname, client_ip_port, ctrack->l7proto);
}
}
}