suricata
detect-tls-certs.c
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1 /* Copyright (C) 2019-2022 Open Information Security Foundation
2  *
3  * You can copy, redistribute or modify this Program under the terms of
4  * the GNU General Public License version 2 as published by the Free
5  * Software Foundation.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * version 2 along with this program; if not, write to the Free Software
14  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15  * 02110-1301, USA.
16  */
17 
18 /**
19  * \file
20  *
21  * \author Mats Klepsland <mats.klepsland@gmail.com>
22  *
23  * Implements support for tls.certs keyword.
24  */
25 
26 #include "suricata-common.h"
27 #include "threads.h"
28 #include "decode.h"
29 #include "detect.h"
30 
31 #include "detect-parse.h"
32 #include "detect-engine.h"
33 #include "detect-engine-buffer.h"
34 #include "detect-engine-mpm.h"
37 #include "detect-content.h"
38 #include "detect-pcre.h"
39 #include "detect-tls-certs.h"
40 #include "detect-engine-uint.h"
41 
42 #include "flow.h"
43 #include "flow-util.h"
44 #include "flow-var.h"
45 
46 #include "util-debug.h"
47 #include "util-spm.h"
48 #include "util-print.h"
49 
50 #include "stream-tcp.h"
51 
52 #include "app-layer.h"
53 #include "app-layer-ssl.h"
54 
55 #include "util-profiling.h"
56 #include "util-unittest.h"
57 #include "util-unittest-helper.h"
58 
59 static int DetectTlsCertsSetup(DetectEngineCtx *, Signature *, const char *);
60 #ifdef UNITTESTS
61 static void DetectTlsCertsRegisterTests(void);
62 #endif
63 
64 static int g_tls_certs_buffer_id = 0;
65 
66 static bool TlsCertsGetData(DetectEngineThreadCtx *det_ctx, const void *txv, const uint8_t flags,
67  uint32_t local_id, const uint8_t **buf, uint32_t *buf_len)
68 {
69  const SSLState *ssl_state = (SSLState *)txv;
70  const SSLStateConnp *connp;
71 
72  if (flags & STREAM_TOSERVER) {
73  connp = &ssl_state->client_connp;
74  } else {
75  connp = &ssl_state->server_connp;
76  }
77 
78  if (TAILQ_EMPTY(&connp->certs)) {
79  return false;
80  }
81 
82  SSLCertsChain *cert;
83  if (local_id == 0) {
84  cert = TAILQ_FIRST(&connp->certs);
85  } else {
86  // TODO optimize ?
87  cert = TAILQ_FIRST(&connp->certs);
88  for (uint32_t i = 0; i < local_id; i++) {
89  cert = TAILQ_NEXT(cert, next);
90  }
91  }
92  if (cert == NULL) {
93  return false;
94  }
95 
96  *buf = cert->cert_data;
97  *buf_len = cert->cert_len;
98  return true;
99 }
100 
101 /**
102  * \brief Registration function for keyword: tls.certs
103  */
105 {
106  sigmatch_table[DETECT_TLS_CERTS].name = "tls.certs";
107  sigmatch_table[DETECT_TLS_CERTS].desc = "sticky buffer to match the TLS certificate buffer";
108  sigmatch_table[DETECT_TLS_CERTS].url = "/rules/tls-keywords.html#tls-certs";
109  sigmatch_table[DETECT_TLS_CERTS].Setup = DetectTlsCertsSetup;
110 #ifdef UNITTESTS
111  sigmatch_table[DETECT_TLS_CERTS].RegisterTests = DetectTlsCertsRegisterTests;
112 #endif
115 
117  TLS_STATE_SERVER_CERT_DONE, TlsCertsGetData, 2);
119  TLS_STATE_CLIENT_CERT_DONE, TlsCertsGetData, 2);
120 
121  DetectBufferTypeSetDescriptionByName("tls.certs", "TLS certificate");
122 
124 
125  g_tls_certs_buffer_id = DetectBufferTypeGetByName("tls.certs");
126 }
127 
128 /**
129  * \brief This function setup the tls.certs modifier keyword
130  *
131  * \param de_ctx Pointer to the Detect Engine Context
132  * \param s Pointer to the Signature to which the keyword belongs
133  * \param str Should hold an empty string always
134  *
135  * \retval 0 On success
136  * \retval -1 On failure
137  */
138 static int DetectTlsCertsSetup(DetectEngineCtx *de_ctx, Signature *s,
139  const char *str)
140 {
141  if (SCDetectBufferSetActiveList(de_ctx, s, g_tls_certs_buffer_id) < 0)
142  return -1;
143 
145  return -1;
146 
147  return 0;
148 }
149 
150 static int g_tls_cert_buffer_id = 0;
151 #define BUFFER_NAME "tls:server_cert_done:generic"
152 #define KEYWORD_ID DETECT_TLS_CHAIN_LEN
153 #define KEYWORD_NAME "tls.cert_chain_len"
154 #define KEYWORD_DESC "match TLS certificate chain length"
155 #define KEYWORD_URL "/rules/tls-keywords.html#tls-cert-chain-len"
156 
157 /**
158  * \internal
159  * \brief Function to match cert chain length in TLS
160  *
161  * \param t Pointer to thread vars.
162  * \param det_ctx Pointer to the pattern matcher thread.
163  * \param f Pointer to the current flow.
164  * \param flags Flags.
165  * \param state App layer state.
166  * \param s Pointer to the Signature.
167  * \param m Pointer to the sigmatch that we will cast into
168  * DetectU64Data.
169  *
170  * \retval 0 no match.
171  * \retval 1 match.
172  */
173 static int DetectTLSCertChainLenMatch(DetectEngineThreadCtx *det_ctx, Flow *f, uint8_t flags,
174  void *state, void *txv, const Signature *s, const SigMatchCtx *ctx)
175 {
176  SCEnter();
177 
178  SSLState *ssl_state = state;
179  if (flags & STREAM_TOCLIENT) {
180  SSLStateConnp *connp = &ssl_state->server_connp;
181  uint32_t cnt = 0;
182  SSLCertsChain *cert;
183  TAILQ_FOREACH (cert, &connp->certs, next) {
184  cnt++;
185  }
186  SCLogDebug("%u certs in chain", cnt);
187 
188  const DetectU32Data *dd = (const DetectU32Data *)ctx;
189  if (DetectU32Match(cnt, dd)) {
190  SCReturnInt(1);
191  }
192  }
193  SCReturnInt(0);
194 }
195 
196 /**
197  * \internal
198  * \brief Function to free memory associated with DetectU64Data.
199  *
200  * \param de_ptr Pointer to DetectU64Data.
201  */
202 static void DetectTLSCertChainLenFree(DetectEngineCtx *de_ctx, void *ptr)
203 {
204  SCDetectU32Free(ptr);
205 }
206 
207 /**
208  * \brief Function to add the parsed tls cert chain len field into the current signature.
209  *
210  * \param de_ctx Pointer to the Detection Engine Context.
211  * \param s Pointer to the Current Signature.
212  * \param rawstr Pointer to the user provided flags options.
213  * \param type Defines if this is notBefore or notAfter.
214  *
215  * \retval 0 on Success.
216  * \retval -1 on Failure.
217  */
218 static int DetectTLSCertChainLenSetup(DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
219 {
221  return -1;
222 
223  DetectU32Data *dd = DetectU32Parse(rawstr);
224  if (dd == NULL) {
225  SCLogError("Parsing \'%s\' failed for %s", rawstr, sigmatch_table[KEYWORD_ID].name);
226  return -1;
227  }
228 
229  if (SigMatchAppendSMToList(de_ctx, s, KEYWORD_ID, (SigMatchCtx *)dd, g_tls_cert_buffer_id) ==
230  NULL) {
231  SCDetectU32Free(dd);
232  return -1;
233  }
234  return 0;
235 }
236 
238 {
242  sigmatch_table[KEYWORD_ID].AppLayerTxMatch = DetectTLSCertChainLenMatch;
243  sigmatch_table[KEYWORD_ID].Setup = DetectTLSCertChainLenSetup;
244  sigmatch_table[KEYWORD_ID].Free = DetectTLSCertChainLenFree;
245 
246  g_tls_cert_buffer_id = DetectBufferTypeGetByName(BUFFER_NAME);
247 }
248 
249 #ifdef UNITTESTS
250 #include "tests/detect-tls-certs.c"
251 #endif
detect-engine-uint.h
SigTableElmt_::url
const char * url
Definition: detect.h:1431
DetectSignatureSetAppProto
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
Definition: detect-parse.c:2313
SSLState_
SSLv[2.0|3.[0|1|2|3]] state structure.
Definition: app-layer-ssl.h:301
detect-content.h
detect-engine.h
SIGMATCH_INFO_STICKY_BUFFER
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1645
DetectU32Match
int DetectU32Match(const uint32_t parg, const DetectUintData_u32 *du32)
Definition: detect-engine-uint.c:31
SSLCertsChain_::cert_len
uint32_t cert_len
Definition: app-layer-ssl.h:230
SigTableElmt_::desc
const char * desc
Definition: detect.h:1430
sigmatch_table
SigTableElmt * sigmatch_table
Definition: detect-parse.c:155
SigTableElmt_::Free
void(* Free)(DetectEngineCtx *, void *)
Definition: detect.h:1418
flow-util.h
SigTableElmt_::name
const char * name
Definition: detect.h:1428
stream-tcp.h
SSLState_::client_connp
SSLStateConnp client_connp
Definition: app-layer-ssl.h:322
ALPROTO_TLS
@ ALPROTO_TLS
Definition: app-layer-protos.h:39
SCLogDebug
#define SCLogDebug(...)
Definition: util-debug.h:269
DetectU32Parse
DetectUintData_u32 * DetectU32Parse(const char *u32str)
This function is used to parse u32 options passed via some u32 keyword.
Definition: detect-engine-uint.c:45
next
struct HtpBodyChunk_ * next
Definition: app-layer-htp.h:0
SSLState_::server_connp
SSLStateConnp server_connp
Definition: app-layer-ssl.h:323
SSLStateConnp_
Definition: app-layer-ssl.h:240
KEYWORD_NAME
#define KEYWORD_NAME
Definition: detect-tls-certs.c:153
threads.h
Flow_
Flow data structure.
Definition: flow.h:356
SigTableElmt_::flags
uint16_t flags
Definition: detect.h:1422
ctx
struct Thresholds ctx
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:931
TAILQ_EMPTY
#define TAILQ_EMPTY(head)
Definition: queue.h:248
DetectBufferTypeSupportsMultiInstance
void DetectBufferTypeSupportsMultiInstance(const char *name)
Definition: detect-engine.c:1107
TAILQ_FOREACH
#define TAILQ_FOREACH(var, head, field)
Definition: queue.h:252
SigTableElmt_::AppLayerTxMatch
int(* AppLayerTxMatch)(DetectEngineThreadCtx *, Flow *, uint8_t flags, void *alstate, void *txv, const Signature *, const SigMatchCtx *)
Definition: detect.h:1399
SCDetectBufferSetActiveList
int SCDetectBufferSetActiveList(DetectEngineCtx *de_ctx, Signature *s, const int list)
Definition: detect-engine-buffer.c:29
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:271
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1413
detect-pcre.h
detect-engine-prefilter.h
util-unittest.h
util-unittest-helper.h
KEYWORD_ID
#define KEYWORD_ID
Definition: detect-tls-certs.c:152
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1157
SIG_FLAG_TOSERVER
#define SIG_FLAG_TOSERVER
Definition: detect.h:270
KEYWORD_DESC
#define KEYWORD_DESC
Definition: detect-tls-certs.c:154
decode.h
util-debug.h
TAILQ_FIRST
#define TAILQ_FIRST(head)
Definition: queue.h:250
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:18
DetectEngineThreadCtx_
Definition: detect.h:1223
SSLCertsChain_
Definition: app-layer-ssl.h:228
util-print.h
SCEnter
#define SCEnter(...)
Definition: util-debug.h:271
detect-engine-mpm.h
detect.h
BUFFER_NAME
#define BUFFER_NAME
Definition: detect-tls-certs.c:151
util-profiling.h
name
const char * name
Definition: tm-threads.c:2123
TLS_STATE_SERVER_CERT_DONE
@ TLS_STATE_SERVER_CERT_DONE
Definition: app-layer-ssl.h:88
DetectTlsCertsRegister
void DetectTlsCertsRegister(void)
Registration function for keyword: tls.certs.
Definition: detect-tls-certs.c:104
SSLCertsChain_::cert_data
uint8_t * cert_data
Definition: app-layer-ssl.h:229
detect-engine-content-inspection.h
SigMatchCtx_
Used to start a pointer to SigMatch context Should never be dereferenced without casting to something...
Definition: detect.h:351
detect-tls-certs.c
cnt
uint32_t cnt
Definition: tmqh-packetpool.h:7
flags
uint8_t flags
Definition: decode-gre.h:0
suricata-common.h
DetectU32Data
DetectUintData_u32 DetectU32Data
Definition: detect-engine-uint.h:41
TAILQ_NEXT
#define TAILQ_NEXT(elm, field)
Definition: queue.h:307
util-spm.h
detect-engine-buffer.h
KEYWORD_URL
#define KEYWORD_URL
Definition: detect-tls-certs.c:155
TLS_STATE_CLIENT_CERT_DONE
@ TLS_STATE_CLIENT_CERT_DONE
Definition: app-layer-ssl.h:80
detect-tls-certs.h
str
#define str(s)
Definition: suricata-common.h:308
SCLogError
#define SCLogError(...)
Macro used to log ERROR messages.
Definition: util-debug.h:261
detect-parse.h
Signature_
Signature container.
Definition: detect.h:670
DETECT_TLS_CERTS
@ DETECT_TLS_CERTS
Definition: detect-engine-register.h:248
DetectTlsCertChainLenRegister
void DetectTlsCertChainLenRegister(void)
Definition: detect-tls-certs.c:237
SIGMATCH_NOOPT
#define SIGMATCH_NOOPT
Definition: detect.h:1620
SigMatchAppendSMToList
SigMatch * SigMatchAppendSMToList(DetectEngineCtx *de_ctx, Signature *s, uint16_t type, SigMatchCtx *ctx, const int list)
Append a SigMatch to the list type.
Definition: detect-parse.c:464
DetectBufferTypeSetDescriptionByName
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
Definition: detect-engine.c:1254
DetectAppLayerMultiRegister
void DetectAppLayerMultiRegister(const char *name, AppProto alproto, uint32_t dir, int progress, InspectionMultiBufferGetDataPtr GetData, int priority)
Definition: detect-engine.c:2153
flow.h
SCReturnInt
#define SCReturnInt(x)
Definition: util-debug.h:275
flow-var.h
app-layer-ssl.h
SigTableElmt_::RegisterTests
void(* RegisterTests)(void)
Definition: detect.h:1420
app-layer.h