suricata
detect-tls-cert-serial.c
Go to the documentation of this file.
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 
88 
91 
94 
97 
98  DetectBufferTypeSetDescriptionByName("tls.cert_serial",
99  "TLS certificate serial number");
100 
101  DetectBufferTypeRegisterSetupCallback("tls.cert_serial",
102  DetectTlsSerialSetupCallback);
103 
105  DetectTlsSerialValidateCallback);
106 
107  g_tls_cert_serial_buffer_id = DetectBufferTypeGetByName("tls.cert_serial");
108 }
109 
110 /**
111  * \brief this function setup the tls_cert_serial modifier keyword used in the rule
112  *
113  * \param de_ctx Pointer to the Detection Engine Context
114  * \param s Pointer to the Signature to which the current keyword belongs
115  * \param str Should hold an empty string always
116  *
117  * \retval 0 On success
118  * \retval -1 On failure
119  */
120 static int DetectTlsSerialSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
121 {
122  if (DetectBufferSetActiveList(de_ctx, s, g_tls_cert_serial_buffer_id) < 0)
123  return -1;
124 
126  return -1;
127 
128  return 0;
129 }
130 
131 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
132  const DetectEngineTransforms *transforms, Flow *f,
133  const uint8_t flow_flags, void *txv, const int list_id)
134 {
135  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
136  if (buffer->inspect == NULL) {
137  const SSLState *ssl_state = (SSLState *)f->alstate;
138  const SSLStateConnp *connp;
139 
140  if (flow_flags & STREAM_TOSERVER) {
141  connp = &ssl_state->client_connp;
142  } else {
143  connp = &ssl_state->server_connp;
144  }
145 
146  if (connp->cert0_serial == NULL) {
147  return NULL;
148  }
149 
150  const uint32_t data_len = strlen(connp->cert0_serial);
151  const uint8_t *data = (uint8_t *)connp->cert0_serial;
152 
153  InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
154  InspectionBufferApplyTransforms(buffer, transforms);
155  }
156 
157  return buffer;
158 }
159 
160 static bool DetectTlsSerialValidateCallback(const Signature *s,
161  const char **sigerror)
162 {
163  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
164  if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
165  continue;
166  const SigMatch *sm = s->init_data->buffers[x].head;
167  for (; sm != NULL; sm = sm->next) {
168  if (sm->type != DETECT_CONTENT)
169  continue;
170 
171  const DetectContentData *cd = (DetectContentData *)sm->ctx;
172 
173  if (cd->flags & DETECT_CONTENT_NOCASE) {
174  *sigerror = "tls.cert_serial should not be used together "
175  "with nocase, since the rule is automatically "
176  "uppercased anyway which makes nocase redundant.";
177  SCLogWarning("rule %u: %s", s->id, *sigerror);
178  }
179 
180  /* no need to worry about this if the content is short enough */
181  if (cd->content_len <= 2)
182  return true;
183 
184  uint32_t u;
185  for (u = 0; u < cd->content_len; u++)
186  if (cd->content[u] == ':')
187  return true;
188 
189  *sigerror = "No colon delimiters ':' detected in content after "
190  "tls.cert_serial. This rule will therefore never "
191  "match.";
192  SCLogWarning("rule %u: %s", s->id, *sigerror);
193 
194  return false;
195  }
196  }
197  return true;
198 }
199 
200 static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
201  Signature *s)
202 {
203  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
204  if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
205  continue;
206  SigMatch *sm = s->init_data->buffers[x].head;
207  for (; sm != NULL; sm = sm->next) {
208  if (sm->type != DETECT_CONTENT)
209  continue;
210 
212 
213  bool changed = false;
214  uint32_t u;
215  for (u = 0; u < cd->content_len; u++) {
216  if (islower(cd->content[u])) {
217  cd->content[u] = u8_toupper(cd->content[u]);
218  changed = true;
219  }
220  }
221 
222  /* recreate the context if changes were made */
223  if (changed) {
224  SpmDestroyCtx(cd->spm_ctx);
225  cd->spm_ctx =
227  }
228  }
229  }
230 }
231 
232 #ifdef UNITTESTS
234 #endif
DETECT_CONTENT_NOCASE
#define DETECT_CONTENT_NOCASE
Definition: detect-content.h:29
SigTableElmt_::url
const char * url
Definition: detect.h:1311
DetectSignatureSetAppProto
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
Definition: detect-parse.c:1742
SignatureInitDataBuffer_::head
SigMatch * head
Definition: detect.h:536
SSLState_
SSLv[2.0|3.[0|1|2|3]] state structure.
Definition: app-layer-ssl.h:290
detect-content.h
detect-engine.h
SIGMATCH_INFO_STICKY_BUFFER
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1512
SigTableElmt_::desc
const char * desc
Definition: detect.h:1310
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:2137
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:1308
stream-tcp.h
DetectEngineTransforms
Definition: detect.h:409
SSLState_::client_connp
SSLStateConnp client_connp
Definition: app-layer-ssl.h:308
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:309
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:1350
SSLStateConnp_
Definition: app-layer-ssl.h:230
InspectionBuffer
Definition: detect.h:374
threads.h
Flow_
Flow data structure.
Definition: flow.h:356
DetectBufferTypeRegisterSetupCallback
void DetectBufferTypeRegisterSetupCallback(const char *name, void(*SetupCallback)(const DetectEngineCtx *, Signature *))
Definition: detect-engine.c:1281
SigTableElmt_::flags
uint16_t flags
Definition: detect.h:1302
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:848
DetectContentData_
Definition: detect-content.h:93
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:267
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1293
detect-pcre.h
detect-engine-prefilter.h
util-unittest.h
InspectionBufferGet
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
Definition: detect-engine.c:1494
util-unittest-helper.h
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1087
SIG_FLAG_TOSERVER
#define SIG_FLAG_TOSERVER
Definition: detect.h:266
decode.h
util-debug.h
DetectBufferTypeRegisterValidateCallback
void DetectBufferTypeRegisterValidateCallback(const char *name, bool(*ValidateCallback)(const Signature *, const char **sigerror))
Definition: detect-engine.c:1299
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1104
util-print.h
detect-engine-mpm.h
detect.h
SigMatch_::next
struct SigMatch_ * next
Definition: detect.h:354
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
DetectAppLayerMpmRegister
void DetectAppLayerMpmRegister(const char *name, int direction, int priority, PrefilterRegisterFunc PrefilterRegister, InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register an app layer keyword for mpm
Definition: detect-engine-mpm.c:146
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:353
DetectContentData_::flags
uint32_t flags
Definition: detect-content.h:104
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:671
SigTableElmt_::alias
const char * alias
Definition: detect.h:1309
suricata-common.h
SigMatch_::type
uint16_t type
Definition: detect.h:351
InspectionBufferApplyTransforms
void InspectionBufferApplyTransforms(InspectionBuffer *buffer, const DetectEngineTransforms *transforms)
Definition: detect-engine.c:1693
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:127
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:592
InspectionBuffer::inspect
const uint8_t * inspect
Definition: detect.h:375
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:1589
Flow_::alstate
void * alstate
Definition: flow.h:481
Signature_::id
uint32_t id
Definition: detect.h:637
detect-parse.h
SignatureInitDataBuffer_::id
uint32_t id
Definition: detect.h:529
Signature_
Signature container.
Definition: detect.h:602
SigMatch_
a single match condition for a signature
Definition: detect.h:350
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:241
SIGMATCH_NOOPT
#define SIGMATCH_NOOPT
Definition: detect.h:1488
DetectAppLayerInspectEngineRegister
void DetectAppLayerInspectEngineRegister(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr Callback, InspectionBufferGetDataPtr GetData)
Registers an app inspection engine.
Definition: detect-engine.c:233
detect-tls-cert-serial.h
DetectEngineCtx_::spm_global_thread_ctx
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:900
DetectBufferTypeSetDescriptionByName
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
Definition: detect-engine.c:1184
flow.h
SpmDestroyCtx
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:183
SignatureInitData_::buffer_index
uint32_t buffer_index
Definition: detect.h:593
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:1300
app-layer.h