suricata
detect-tls-cert-serial.c
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1 /* Copyright (C) 2017-2022 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.cert_serial 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-mpm.h"
35 #include "detect-content.h"
36 #include "detect-pcre.h"
37 
38 #include "flow.h"
39 #include "flow-util.h"
40 #include "flow-var.h"
41 
42 #include "util-debug.h"
43 #include "util-spm.h"
44 #include "util-print.h"
45 
46 #include "stream-tcp.h"
47 
48 #include "app-layer.h"
49 #include "app-layer-ssl.h"
50 #include "detect-tls-cert-serial.h"
51 
52 #include "util-unittest.h"
53 #include "util-unittest-helper.h"
54 
55 static int DetectTlsSerialSetup(DetectEngineCtx *, Signature *, const char *);
56 #ifdef UNITTESTS
57 static void DetectTlsSerialRegisterTests(void);
58 #endif
59 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
60  const DetectEngineTransforms *transforms,
61  Flow *f, const uint8_t flow_flags,
62  void *txv, const int list_id);
63 static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
64  Signature *s);
65 static bool DetectTlsSerialValidateCallback(const Signature *s,
66  const char **sigerror);
67 static int g_tls_cert_serial_buffer_id = 0;
68 
69 /**
70  * \brief Registration function for keyword: tls.cert_serial
71  */
73 {
74  sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].name = "tls.cert_serial";
75  sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].alias = "tls_cert_serial";
77  "sticky buffer to match the TLS cert serial buffer";
78  sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].url = "/rules/tls-keywords.html#tls-cert-serial";
79  sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].Setup = DetectTlsSerialSetup;
80 #ifdef UNITTESTS
81  sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].RegisterTests = DetectTlsSerialRegisterTests;
82 #endif
85 
89 
90  DetectAppLayerMpmRegister2("tls.cert_serial", SIG_FLAG_TOCLIENT, 2,
93 
96 
99 
100  DetectBufferTypeSetDescriptionByName("tls.cert_serial",
101  "TLS certificate serial number");
102 
103  DetectBufferTypeRegisterSetupCallback("tls.cert_serial",
104  DetectTlsSerialSetupCallback);
105 
107  DetectTlsSerialValidateCallback);
108 
109  g_tls_cert_serial_buffer_id = DetectBufferTypeGetByName("tls.cert_serial");
110 }
111 
112 /**
113  * \brief this function setup the tls_cert_serial modifier keyword used in the rule
114  *
115  * \param de_ctx Pointer to the Detection Engine Context
116  * \param s Pointer to the Signature to which the current keyword belongs
117  * \param str Should hold an empty string always
118  *
119  * \retval 0 On success
120  * \retval -1 On failure
121  */
122 static int DetectTlsSerialSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
123 {
124  if (DetectBufferSetActiveList(de_ctx, s, g_tls_cert_serial_buffer_id) < 0)
125  return -1;
126 
128  return -1;
129 
130  return 0;
131 }
132 
133 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
134  const DetectEngineTransforms *transforms, Flow *f,
135  const uint8_t flow_flags, void *txv, const int list_id)
136 {
137  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
138  if (buffer->inspect == NULL) {
139  const SSLState *ssl_state = (SSLState *)f->alstate;
140  const SSLStateConnp *connp;
141 
142  if (flow_flags & STREAM_TOSERVER) {
143  connp = &ssl_state->client_connp;
144  } else {
145  connp = &ssl_state->server_connp;
146  }
147 
148  if (connp->cert0_serial == NULL) {
149  return NULL;
150  }
151 
152  const uint32_t data_len = strlen(connp->cert0_serial);
153  const uint8_t *data = (uint8_t *)connp->cert0_serial;
154 
155  InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
156  InspectionBufferApplyTransforms(buffer, transforms);
157  }
158 
159  return buffer;
160 }
161 
162 static bool DetectTlsSerialValidateCallback(const Signature *s,
163  const char **sigerror)
164 {
165  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
166  if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
167  continue;
168  const SigMatch *sm = s->init_data->buffers[x].head;
169  for (; sm != NULL; sm = sm->next) {
170  if (sm->type != DETECT_CONTENT)
171  continue;
172 
173  const DetectContentData *cd = (DetectContentData *)sm->ctx;
174 
175  if (cd->flags & DETECT_CONTENT_NOCASE) {
176  *sigerror = "tls.cert_serial should not be used together "
177  "with nocase, since the rule is automatically "
178  "uppercased anyway which makes nocase redundant.";
179  SCLogWarning("rule %u: %s", s->id, *sigerror);
180  }
181 
182  /* no need to worry about this if the content is short enough */
183  if (cd->content_len <= 2)
184  return true;
185 
186  uint32_t u;
187  for (u = 0; u < cd->content_len; u++)
188  if (cd->content[u] == ':')
189  return true;
190 
191  *sigerror = "No colon delimiters ':' detected in content after "
192  "tls.cert_serial. This rule will therefore never "
193  "match.";
194  SCLogWarning("rule %u: %s", s->id, *sigerror);
195 
196  return false;
197  }
198  }
199  return true;
200 }
201 
202 static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
203  Signature *s)
204 {
205  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
206  if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
207  continue;
208  SigMatch *sm = s->init_data->buffers[x].head;
209  for (; sm != NULL; sm = sm->next) {
210  if (sm->type != DETECT_CONTENT)
211  continue;
212 
214 
215  bool changed = false;
216  uint32_t u;
217  for (u = 0; u < cd->content_len; u++) {
218  if (islower(cd->content[u])) {
219  cd->content[u] = u8_toupper(cd->content[u]);
220  changed = true;
221  }
222  }
223 
224  /* recreate the context if changes were made */
225  if (changed) {
226  SpmDestroyCtx(cd->spm_ctx);
227  cd->spm_ctx =
229  }
230  }
231  }
232 }
233 
234 #ifdef UNITTESTS
236 #endif
DETECT_CONTENT_NOCASE
#define DETECT_CONTENT_NOCASE
Definition: detect-content.h:29
SigTableElmt_::url
const char * url
Definition: detect.h:1287
DetectSignatureSetAppProto
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
Definition: detect-parse.c:1737
SignatureInitDataBuffer_::head
SigMatch * head
Definition: detect.h:524
SSLState_
SSLv[2.0|3.[0|1|2|3]] state structure.
Definition: app-layer-ssl.h:284
detect-content.h
detect-engine.h
DetectAppLayerMpmRegister2
void DetectAppLayerMpmRegister2(const char *name, int direction, int priority, PrefilterRegisterFunc PrefilterRegister, InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register a MPM engine
Definition: detect-engine-mpm.c:89
SIGMATCH_INFO_STICKY_BUFFER
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1490
SigTableElmt_::desc
const char * desc
Definition: detect.h:1286
TLS_STATE_CERT_READY
@ TLS_STATE_CERT_READY
Definition: app-layer-ssl.h:78
DetectEngineInspectBufferGeneric
uint8_t DetectEngineInspectBufferGeneric(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx, const DetectEngineAppInspectionEngine *engine, const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv, uint64_t tx_id)
Do the content inspection & validation for a signature.
Definition: detect-engine.c:2174
flow-util.h
DetectTlsSerialRegister
void DetectTlsSerialRegister(void)
Registration function for keyword: tls.cert_serial.
Definition: detect-tls-cert-serial.c:72
SigTableElmt_::name
const char * name
Definition: detect.h:1284
stream-tcp.h
DetectEngineTransforms
Definition: detect.h:403
SSLState_::client_connp
SSLStateConnp client_connp
Definition: app-layer-ssl.h:302
DETECT_CONTENT
@ DETECT_CONTENT
Definition: detect-engine-register.h:62
ALPROTO_TLS
@ ALPROTO_TLS
Definition: app-layer-protos.h:33
detect-tls-cert-serial.c
SSLState_::server_connp
SSLStateConnp server_connp
Definition: app-layer-ssl.h:303
u8_toupper
#define u8_toupper(c)
Definition: suricata-common.h:437
DetectBufferSetActiveList
int DetectBufferSetActiveList(DetectEngineCtx *de_ctx, Signature *s, const int list)
Definition: detect-engine.c:1387
SSLStateConnp_
Definition: app-layer-ssl.h:228
InspectionBuffer
Definition: detect.h:368
threads.h
Flow_
Flow data structure.
Definition: flow.h:349
DetectBufferTypeRegisterSetupCallback
void DetectBufferTypeRegisterSetupCallback(const char *name, void(*SetupCallback)(const DetectEngineCtx *, Signature *))
Definition: detect-engine.c:1318
SigTableElmt_::flags
uint16_t flags
Definition: detect.h:1278
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:832
DetectContentData_
Definition: detect-content.h:93
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:260
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1269
detect-pcre.h
detect-engine-prefilter.h
util-unittest.h
InspectionBufferGet
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
Definition: detect-engine.c:1531
util-unittest-helper.h
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1124
SIG_FLAG_TOSERVER
#define SIG_FLAG_TOSERVER
Definition: detect.h:259
decode.h
util-debug.h
DetectBufferTypeRegisterValidateCallback
void DetectBufferTypeRegisterValidateCallback(const char *name, bool(*ValidateCallback)(const Signature *, const char **sigerror))
Definition: detect-engine.c:1336
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1080
util-print.h
detect-engine-mpm.h
detect.h
SigMatch_::next
struct SigMatch_ * next
Definition: detect.h:348
PrefilterGenericMpmRegister
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)
Definition: detect-engine-prefilter.c:745
SCLogWarning
#define SCLogWarning(...)
Macro used to log WARNING messages.
Definition: util-debug.h:249
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:347
DetectAppLayerInspectEngineRegister2
void DetectAppLayerInspectEngineRegister2(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr2 Callback2, InspectionBufferGetDataPtr GetData)
register inspect engine at start up time
Definition: detect-engine.c:216
DetectContentData_::flags
uint32_t flags
Definition: detect-content.h:104
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:659
SigTableElmt_::alias
const char * alias
Definition: detect.h:1285
suricata-common.h
SigMatch_::type
uint16_t type
Definition: detect.h:345
InspectionBufferApplyTransforms
void InspectionBufferApplyTransforms(InspectionBuffer *buffer, const DetectEngineTransforms *transforms)
Definition: detect-engine.c:1730
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:129
util-spm.h
DetectContentData_::content
uint8_t * content
Definition: detect-content.h:94
DetectContentData_::spm_ctx
SpmCtx * spm_ctx
Definition: detect-content.h:111
SignatureInitData_::buffers
SignatureInitDataBuffer * buffers
Definition: detect.h:577
InspectionBuffer::inspect
const uint8_t * inspect
Definition: detect.h:369
str
#define str(s)
Definition: suricata-common.h:291
InspectionBufferSetup
void InspectionBufferSetup(DetectEngineThreadCtx *det_ctx, const int list_id, InspectionBuffer *buffer, const uint8_t *data, const uint32_t data_len)
setup the buffer with our initial data
Definition: detect-engine.c:1626
Flow_::alstate
void * alstate
Definition: flow.h:474
Signature_::id
uint32_t id
Definition: detect.h:622
detect-parse.h
SignatureInitDataBuffer_::id
uint32_t id
Definition: detect.h:517
Signature_
Signature container.
Definition: detect.h:587
SigMatch_
a single match condition for a signature
Definition: detect.h:344
DetectContentData_::content_len
uint16_t content_len
Definition: detect-content.h:95
DETECT_AL_TLS_CERT_SERIAL
@ DETECT_AL_TLS_CERT_SERIAL
Definition: detect-engine-register.h:234
SIGMATCH_NOOPT
#define SIGMATCH_NOOPT
Definition: detect.h:1466
detect-tls-cert-serial.h
DetectEngineCtx_::spm_global_thread_ctx
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:885
DetectBufferTypeSetDescriptionByName
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
Definition: detect-engine.c:1221
flow.h
SpmDestroyCtx
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:183
SignatureInitData_::buffer_index
uint32_t buffer_index
Definition: detect.h:578
flow-var.h
SpmInitCtx
SpmCtx * SpmInitCtx(const uint8_t *needle, uint16_t needle_len, int nocase, SpmGlobalThreadCtx *global_thread_ctx)
Definition: util-spm.c:173
app-layer-ssl.h
SigTableElmt_::RegisterTests
void(* RegisterTests)(void)
Definition: detect.h:1276
app-layer.h