suricata
detect-tls-cert-serial.c
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1 /* Copyright (C) 2017 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 
94  DetectBufferTypeSetDescriptionByName("tls.cert_serial",
95  "TLS certificate serial number");
96 
97  DetectBufferTypeRegisterSetupCallback("tls.cert_serial",
98  DetectTlsSerialSetupCallback);
99 
101  DetectTlsSerialValidateCallback);
102 
103  g_tls_cert_serial_buffer_id = DetectBufferTypeGetByName("tls.cert_serial");
104 }
105 
106 /**
107  * \brief this function setup the tls_cert_serial modifier keyword used in the rule
108  *
109  * \param de_ctx Pointer to the Detection Engine Context
110  * \param s Pointer to the Signature to which the current keyword belongs
111  * \param str Should hold an empty string always
112  *
113  * \retval 0 On success
114  * \retval -1 On failure
115  */
116 static int DetectTlsSerialSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
117 {
118  if (DetectBufferSetActiveList(s, g_tls_cert_serial_buffer_id) < 0)
119  return -1;
120 
122  return -1;
123 
124  return 0;
125 }
126 
127 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
128  const DetectEngineTransforms *transforms, Flow *f,
129  const uint8_t flow_flags, void *txv, const int list_id)
130 {
131  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
132  if (buffer->inspect == NULL) {
133  const SSLState *ssl_state = (SSLState *)f->alstate;
134 
135  if (ssl_state->server_connp.cert0_serial == NULL) {
136  return NULL;
137  }
138 
139  const uint32_t data_len = strlen(ssl_state->server_connp.cert0_serial);
140  const uint8_t *data = (uint8_t *)ssl_state->server_connp.cert0_serial;
141 
142  InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
143  InspectionBufferApplyTransforms(buffer, transforms);
144  }
145 
146  return buffer;
147 }
148 
149 static bool DetectTlsSerialValidateCallback(const Signature *s,
150  const char **sigerror)
151 {
152  const SigMatch *sm = s->init_data->smlists[g_tls_cert_serial_buffer_id];
153  for ( ; sm != NULL; sm = sm->next)
154  {
155  if (sm->type != DETECT_CONTENT)
156  continue;
157 
158  const DetectContentData *cd = (DetectContentData *)sm->ctx;
159 
160  if (cd->flags & DETECT_CONTENT_NOCASE) {
161  *sigerror = "tls.cert_serial should not be used together "
162  "with nocase, since the rule is automatically "
163  "uppercased anyway which makes nocase redundant.";
164  SCLogWarning(SC_WARN_POOR_RULE, "rule %u: %s", s->id, *sigerror);
165  }
166 
167  /* no need to worry about this if the content is short enough */
168  if (cd->content_len <= 2)
169  return true;
170 
171  uint32_t u;
172  for (u = 0; u < cd->content_len; u++)
173  if (cd->content[u] == ':')
174  return true;
175 
176  *sigerror = "No colon delimiters ':' detected in content after "
177  "tls.cert_serial. This rule will therefore never "
178  "match.";
179  SCLogWarning(SC_WARN_POOR_RULE, "rule %u: %s", s->id, *sigerror);
180 
181  return false;
182  }
183 
184  return true;
185 }
186 
187 static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
188  Signature *s)
189 {
190  SigMatch *sm = s->init_data->smlists[g_tls_cert_serial_buffer_id];
191  for ( ; sm != NULL; sm = sm->next)
192  {
193  if (sm->type != DETECT_CONTENT)
194  continue;
195 
197 
198  bool changed = false;
199  uint32_t u;
200  for (u = 0; u < cd->content_len; u++)
201  {
202  if (islower(cd->content[u])) {
203  cd->content[u] = u8_toupper(cd->content[u]);
204  changed = true;
205  }
206  }
207 
208  /* recreate the context if changes were made */
209  if (changed) {
210  SpmDestroyCtx(cd->spm_ctx);
211  cd->spm_ctx = SpmInitCtx(cd->content, cd->content_len, 1,
213  }
214  }
215 }
216 
217 #ifdef UNITTESTS
219 #endif
DETECT_CONTENT_NOCASE
#define DETECT_CONTENT_NOCASE
Definition: detect-content.h:29
SigTableElmt_::url
const char * url
Definition: detect.h:1238
DetectSignatureSetAppProto
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
Definition: detect-parse.c:1493
SSLState_
SSLv[2.0|3.[0|1|2|3]] state structure.
Definition: app-layer-ssl.h:288
detect-content.h
detect-engine.h
SIGMATCH_INFO_STICKY_BUFFER
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1445
SigTableElmt_::desc
const char * desc
Definition: detect.h:1237
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:1994
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:1235
stream-tcp.h
DetectEngineTransforms
Definition: detect.h:371
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:307
u8_toupper
#define u8_toupper(c)
Definition: suricata-common.h:426
InspectionBuffer
Definition: detect.h:337
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:1262
PrefilterGenericMpmRegister
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistery *mpm_reg, int list_id)
Definition: detect-engine-prefilter.c:749
SigTableElmt_::flags
uint16_t flags
Definition: detect.h:1229
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:784
DetectContentData_
Definition: detect-content.h:86
TLS_STATE_CERT_READY
@ TLS_STATE_CERT_READY
Definition: app-layer-ssl.h:78
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:229
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1220
detect-pcre.h
detect-engine-prefilter.h
util-unittest.h
InspectionBufferGet
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
Definition: detect-engine.c:1369
util-unittest-helper.h
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1086
SC_WARN_POOR_RULE
@ SC_WARN_POOR_RULE
Definition: util-error.h:309
decode.h
util-debug.h
DetectBufferTypeRegisterValidateCallback
void DetectBufferTypeRegisterValidateCallback(const char *name, bool(*ValidateCallback)(const Signature *, const char **sigerror))
Definition: detect-engine.c:1280
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1024
util-print.h
detect-engine-mpm.h
detect.h
SigMatch_::next
struct SigMatch_ * next
Definition: detect.h:317
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:316
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:228
DetectContentData_::flags
uint32_t flags
Definition: detect-content.h:97
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:610
SignatureInitData_::smlists
struct SigMatch_ ** smlists
Definition: detect.h:533
DetectAppLayerMpmRegister2
void DetectAppLayerMpmRegister2(const char *name, int direction, int priority, int(*PrefilterRegister)(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistery *mpm_reg, int list_id), InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register a MPM engine
Definition: detect-engine-mpm.c:89
SigTableElmt_::alias
const char * alias
Definition: detect.h:1236
suricata-common.h
SigMatch_::type
uint16_t type
Definition: detect.h:314
InspectionBufferApplyTransforms
void InspectionBufferApplyTransforms(InspectionBuffer *buffer, const DetectEngineTransforms *transforms)
Definition: detect-engine.c:1552
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:76
util-spm.h
DetectContentData_::content
uint8_t * content
Definition: detect-content.h:87
DetectContentData_::spm_ctx
SpmCtx * spm_ctx
Definition: detect-content.h:104
InspectionBuffer::inspect
const uint8_t * inspect
Definition: detect.h:338
str
#define str(s)
Definition: suricata-common.h:280
SCLogWarning
#define SCLogWarning(err_code,...)
Macro used to log WARNING messages.
Definition: util-debug.h:242
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:1450
Flow_::alstate
void * alstate
Definition: flow.h:489
Signature_::id
uint32_t id
Definition: detect.h:573
detect-parse.h
Signature_
Signature container.
Definition: detect.h:539
SigMatch_
a single match condition for a signature
Definition: detect.h:313
DetectContentData_::content_len
uint16_t content_len
Definition: detect-content.h:88
DETECT_AL_TLS_CERT_SERIAL
@ DETECT_AL_TLS_CERT_SERIAL
Definition: detect-engine-register.h:229
SIGMATCH_NOOPT
#define SIGMATCH_NOOPT
Definition: detect.h:1421
detect-tls-cert-serial.h
DetectEngineCtx_::spm_global_thread_ctx
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:839
DetectBufferSetActiveList
int DetectBufferSetActiveList(Signature *s, const int list)
Definition: detect-engine.c:1300
DetectBufferTypeSetDescriptionByName
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
Definition: detect-engine.c:1183
flow.h
SpmDestroyCtx
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:184
flow-var.h
SSLStateConnp_::cert0_serial
char * cert0_serial
Definition: app-layer-ssl.h:254
SpmInitCtx
SpmCtx * SpmInitCtx(const uint8_t *needle, uint16_t needle_len, int nocase, SpmGlobalThreadCtx *global_thread_ctx)
Definition: util-spm.c:174
app-layer-ssl.h
SigTableElmt_::RegisterTests
void(* RegisterTests)(void)
Definition: detect.h:1227
app-layer.h