suricata
detect-id.c
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1 /* Copyright (C) 2007-2021 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 Pablo Rincon Crespo <pablo.rincon.crespo@gmail.com>
22  *
23  * Implements the id keyword
24  */
25 
26 #include "suricata-common.h"
27 #include "decode.h"
28 #include "detect.h"
29 
30 #include "detect-parse.h"
31 #include "detect-engine.h"
32 #include "detect-engine-mpm.h"
34 
35 #include "detect-id.h"
36 #include "flow.h"
37 #include "flow-var.h"
38 
39 #include "util-debug.h"
40 #include "util-byte.h"
41 #include "util-unittest.h"
42 #include "util-unittest-helper.h"
43 
44 /**
45  * \brief Regex for parsing "id" option, matching number or "number"
46  */
47 #define PARSE_REGEX "^\\s*([0-9]{1,5}|\"[0-9]{1,5}\")\\s*$"
48 
49 static DetectParseRegex parse_regex;
50 
51 static int DetectIdMatch (DetectEngineThreadCtx *, Packet *,
52  const Signature *, const SigMatchCtx *);
53 static int DetectIdSetup (DetectEngineCtx *, Signature *, const char *);
54 #ifdef UNITTESTS
55 static void DetectIdRegisterTests(void);
56 #endif
57 void DetectIdFree(DetectEngineCtx *, void *);
58 
59 static int PrefilterSetupId(DetectEngineCtx *de_ctx, SigGroupHead *sgh);
60 static bool PrefilterIdIsPrefilterable(const Signature *s);
61 
62 /**
63  * \brief Registration function for keyword: id
64  */
65 void DetectIdRegister (void)
66 {
68  sigmatch_table[DETECT_ID].desc = "match on a specific IP ID value";
69  sigmatch_table[DETECT_ID].url = "/rules/header-keywords.html#id";
70  sigmatch_table[DETECT_ID].Match = DetectIdMatch;
71  sigmatch_table[DETECT_ID].Setup = DetectIdSetup;
73 #ifdef UNITTESTS
74  sigmatch_table[DETECT_ID].RegisterTests = DetectIdRegisterTests;
75 #endif
76  sigmatch_table[DETECT_ID].SupportsPrefilter = PrefilterIdIsPrefilterable;
77  sigmatch_table[DETECT_ID].SetupPrefilter = PrefilterSetupId;
78 
79  DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
80 }
81 
82 /**
83  * \brief This function is used to match the specified id on a packet
84  *
85  * \param t pointer to thread vars
86  * \param det_ctx pointer to the pattern matcher thread
87  * \param p pointer to the current packet
88  * \param m pointer to the sigmatch that we will cast into DetectIdData
89  *
90  * \retval 0 no match
91  * \retval 1 match
92  */
93 static int DetectIdMatch (DetectEngineThreadCtx *det_ctx, Packet *p,
94  const Signature *s, const SigMatchCtx *ctx)
95 {
96  const DetectIdData *id_d = (const DetectIdData *)ctx;
97 
98  /**
99  * To match a ipv4 packet with a "id" rule
100  */
101  if (!PKT_IS_IPV4(p) || PKT_IS_PSEUDOPKT(p)) {
102  return 0;
103  }
104 
105  if (id_d->id == IPV4_GET_IPID(p)) {
106  SCLogDebug("IPV4 Proto and matched with ip_id: %u.\n",
107  id_d->id);
108  return 1;
109  }
110 
111  return 0;
112 }
113 
114 /**
115  * \brief This function is used to parse IPV4 ip_id passed via keyword: "id"
116  *
117  * \param idstr Pointer to the user provided id option
118  *
119  * \retval id_d pointer to DetectIdData on success
120  * \retval NULL on failure
121  */
122 static DetectIdData *DetectIdParse (const char *idstr)
123 {
124  uint16_t temp;
125  DetectIdData *id_d = NULL;
126  int res = 0;
127  size_t pcre2len;
128  pcre2_match_data *match = NULL;
129 
130  int ret = DetectParsePcreExec(&parse_regex, &match, idstr, 0, 0);
131 
132  if (ret < 1 || ret > 3) {
133  SCLogError("invalid id option '%s'. The id option "
134  "value must be in the range %u - %u",
136  goto error;
137  }
138 
139  char copy_str[128] = "";
140  char *tmp_str;
141  pcre2len = sizeof(copy_str);
142  res = pcre2_substring_copy_bynumber(match, 1, (PCRE2_UCHAR8 *)copy_str, &pcre2len);
143  if (res < 0) {
144  SCLogError("pcre2_substring_copy_bynumber failed");
145  goto error;
146  }
147  tmp_str = copy_str;
148 
149  /* Let's see if we need to scape "'s */
150  if (tmp_str[0] == '"')
151  {
152  tmp_str[strlen(tmp_str) - 1] = '\0';
153  tmp_str += 1;
154  }
155 
156  /* ok, fill the id data */
157  if (StringParseUint16(&temp, 10, 0, (const char *)tmp_str) < 0) {
158  SCLogError("invalid id option '%s'", tmp_str);
159  goto error;
160  }
161 
162  /* We have a correct id option */
163  id_d = SCMalloc(sizeof(DetectIdData));
164  if (unlikely(id_d == NULL))
165  goto error;
166 
167  id_d->id = temp;
168 
169  SCLogDebug("detect-id: will look for ip_id: %u\n", id_d->id);
170  pcre2_match_data_free(match);
171  return id_d;
172 
173 error:
174  if (match) {
175  pcre2_match_data_free(match);
176  }
177  return NULL;
178 }
179 
180 /**
181  * \brief this function is used to add the parsed "id" option
182  * \brief into the current signature
183  *
184  * \param de_ctx pointer to the Detection Engine Context
185  * \param s pointer to the Current Signature
186  * \param idstr pointer to the user provided "id" option
187  *
188  * \retval 0 on Success
189  * \retval -1 on Failure
190  */
191 int DetectIdSetup (DetectEngineCtx *de_ctx, Signature *s, const char *idstr)
192 {
193  DetectIdData *id_d = NULL;
194 
195  id_d = DetectIdParse(idstr);
196  if (id_d == NULL)
197  return -1;
198 
199  /* Okay so far so good, lets get this into a SigMatch
200  * and put it in the Signature. */
202  NULL) {
203  DetectIdFree(de_ctx, id_d);
204  return -1;
205  }
207  return 0;
208 }
209 
210 /**
211  * \brief this function will free memory associated with DetectIdData
212  *
213  * \param id_d pointer to DetectIdData
214  */
216 {
217  DetectIdData *id_d = (DetectIdData *)ptr;
218  SCFree(id_d);
219 }
220 
221 /* prefilter code */
222 
223 static void
224 PrefilterPacketIdMatch(DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx)
225 {
226  const PrefilterPacketHeaderCtx *ctx = pectx;
227 
228  if (!PKT_IS_IPV4(p) || PKT_IS_PSEUDOPKT(p)) {
229  return;
230  }
231 
232  if (!PrefilterPacketHeaderExtraMatch(ctx, p))
233  return;
234 
235  if (IPV4_GET_IPID(p) == ctx->v1.u16[0])
236  {
237  SCLogDebug("packet matches IP id %u", ctx->v1.u16[0]);
238  PrefilterAddSids(&det_ctx->pmq, ctx->sigs_array, ctx->sigs_cnt);
239  }
240 }
241 
242 static void
243 PrefilterPacketIdSet(PrefilterPacketHeaderValue *v, void *smctx)
244 {
245  const DetectIdData *a = smctx;
246  v->u16[0] = a->id;
247 }
248 
249 static bool
250 PrefilterPacketIdCompare(PrefilterPacketHeaderValue v, void *smctx)
251 {
252  const DetectIdData *a = smctx;
253  if (v.u16[0] == a->id)
254  return true;
255  return false;
256 }
257 
258 static int PrefilterSetupId(DetectEngineCtx *de_ctx, SigGroupHead *sgh)
259 {
261  PrefilterPacketIdSet,
262  PrefilterPacketIdCompare,
263  PrefilterPacketIdMatch);
264 }
265 
266 static bool PrefilterIdIsPrefilterable(const Signature *s)
267 {
268  const SigMatch *sm;
269  for (sm = s->init_data->smlists[DETECT_SM_LIST_MATCH] ; sm != NULL; sm = sm->next) {
270  switch (sm->type) {
271  case DETECT_ID:
272  return true;
273  }
274  }
275  return false;
276 }
277 
278 #ifdef UNITTESTS /* UNITTESTS */
279 
280 /**
281  * \test DetectIdTestParse01 is a test to make sure that we parse the "id"
282  * option correctly when given valid id option
283  */
284 static int DetectIdTestParse01 (void)
285 {
286  DetectIdData *id_d = DetectIdParse(" 35402 ");
287 
288  FAIL_IF_NULL(id_d);
289  FAIL_IF_NOT(id_d->id == 35402);
290 
291  DetectIdFree(NULL, id_d);
292 
293  PASS;
294 }
295 
296 /**
297  * \test DetectIdTestParse02 is a test to make sure that we parse the "id"
298  * option correctly when given an invalid id option
299  * it should return id_d = NULL
300  */
301 static int DetectIdTestParse02 (void)
302 {
303  DetectIdData *id_d = DetectIdParse("65537");
304 
305  FAIL_IF_NOT_NULL(id_d);
306 
307  PASS;
308 }
309 
310 /**
311  * \test DetectIdTestParse03 is a test to make sure that we parse the "id"
312  * option correctly when given an invalid id option
313  * it should return id_d = NULL
314  */
315 static int DetectIdTestParse03 (void)
316 {
317  DetectIdData *id_d = DetectIdParse("12what?");
318 
319  FAIL_IF_NOT_NULL(id_d);
320 
321  PASS;
322 }
323 
324 /**
325  * \test DetectIdTestParse04 is a test to make sure that we parse the "id"
326  * option correctly when given valid id option but wrapped with "'s
327  */
328 static int DetectIdTestParse04 (void)
329 {
330  /* yep, look if we trim blank spaces correctly and ignore "'s */
331  DetectIdData *id_d = DetectIdParse(" \"35402\" ");
332 
333  FAIL_IF_NULL(id_d);
334  FAIL_IF_NOT(id_d->id == 35402);
335 
336  DetectIdFree(NULL, id_d);
337 
338  PASS;
339 }
340 
341 /**
342  * \test DetectIdTestSig01
343  * \brief Test to check "id" keyword with constructed packets
344  */
345 static int DetectIdTestMatch01(void)
346 {
347  uint8_t *buf = (uint8_t *)"Hi all!";
348  uint16_t buflen = strlen((char *)buf);
349  Packet *p[3];
350  p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
351  p[1] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_UDP);
352  p[2] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_ICMP);
353 
354  FAIL_IF_NULL(p[0]);
355  FAIL_IF_NULL(p[1]);
356  FAIL_IF_NULL(p[2]);
357 
358  /* TCP IP id = 1234 */
359  p[0]->ip4h->ip_id = htons(1234);
360 
361  /* UDP IP id = 5678 */
362  p[1]->ip4h->ip_id = htons(5678);
363 
364  /* UDP IP id = 91011 */
365  p[2]->ip4h->ip_id = htons(5101);
366 
367  const char *sigs[3];
368  sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; id:1234; sid:1;)";
369  sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; id:5678; sid:2;)";
370  sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; id:5101; sid:3;)";
371 
372  uint32_t sid[3] = {1, 2, 3};
373 
374  uint32_t results[3][3] = {
375  /* packet 0 match sid 1 but should not match sid 2 */
376  {1, 0, 0},
377  /* packet 1 should not match */
378  {0, 1, 0},
379  /* packet 2 should not match */
380  {0, 0, 1} };
381 
382  FAIL_IF_NOT(UTHGenericTest(p, 3, sigs, sid, (uint32_t *)results, 3));
383 
384  UTHFreePackets(p, 3);
385 
386  PASS;
387 }
388 
389 /**
390  * \brief this function registers unit tests for DetectId
391  */
392 void DetectIdRegisterTests(void)
393 {
394  UtRegisterTest("DetectIdTestParse01", DetectIdTestParse01);
395  UtRegisterTest("DetectIdTestParse02", DetectIdTestParse02);
396  UtRegisterTest("DetectIdTestParse03", DetectIdTestParse03);
397  UtRegisterTest("DetectIdTestParse04", DetectIdTestParse04);
398  UtRegisterTest("DetectIdTestMatch01", DetectIdTestMatch01);
399 
400 }
401 #endif /* UNITTESTS */
util-byte.h
SigTableElmt_::url
const char * url
Definition: detect.h:1296
detect-engine.h
FAIL_IF_NULL
#define FAIL_IF_NULL(expr)
Fail a test if expression evaluates to NULL.
Definition: util-unittest.h:89
SignatureInitData_::smlists
struct SigMatch_ * smlists[DETECT_SM_LIST_MAX]
Definition: detect.h:578
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const char * desc
Definition: detect.h:1295
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void(* Free)(DetectEngineCtx *, void *)
Definition: detect.h:1283
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Definition: detect-parse.h:62
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const char * name
Definition: detect.h:1293
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#define PKT_IS_PSEUDOPKT(p)
return 1 if the packet is a pseudo packet
Definition: decode.h:1074
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Container for matching data for a signature group.
Definition: detect.h:1445
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#define unlikely(expr)
Definition: util-optimize.h:35
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void UtRegisterTest(const char *name, int(*TestFn)(void))
Register unit test.
Definition: util-unittest.c:103
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#define SCLogDebug(...)
Definition: util-debug.h:269
DETECT_ID
@ DETECT_ID
Definition: detect-engine-register.h:83
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struct DetectRfbSecresult_ results[]
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Definition: detect.h:1201
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main detection engine ctx
Definition: detect.h:836
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uint16_t id
Definition: detect-id.h:31
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int StringParseUint16(uint16_t *res, int base, size_t len, const char *str)
Definition: util-byte.c:337
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Definition: detect-engine-prefilter-common.h:43
PARSE_REGEX
#define PARSE_REGEX
Regex for parsing "id" option, matching number or "number".
Definition: detect-id.c:47
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uint16_t ip_id
Definition: decode-ipv4.h:76
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Packet * UTHBuildPacket(uint8_t *payload, uint16_t payload_len, uint8_t ipproto)
UTHBuildPacket is a wrapper that build packets with default ip and port fields.
Definition: util-unittest-helper.c:340
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int DetectParsePcreExec(DetectParseRegex *parse_regex, pcre2_match_data **match, const char *str, int start_offset, int options)
Definition: detect-parse.c:2674
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uint32_t sigs_cnt
Definition: detect-engine-prefilter-common.h:42
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int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1278
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uint16_t u16[8]
Definition: detect-engine-prefilter-common.h:25
util-unittest.h
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FAIL_IF_NOT
#define FAIL_IF_NOT(expr)
Fail a test if expression evaluates to false.
Definition: util-unittest.h:82
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int(* SetupPrefilter)(DetectEngineCtx *de_ctx, struct SigGroupHead_ *sgh)
Definition: detect.h:1281
PrefilterPacketHeaderCtx_
Definition: detect-engine-prefilter-common.h:35
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FAIL_IF_NOT_NULL
#define FAIL_IF_NOT_NULL(expr)
Fail a test if expression evaluates to non-NULL.
Definition: util-unittest.h:96
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PASS
#define PASS
Pass the test.
Definition: util-unittest.h:105
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DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
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Definition: detect.h:1092
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void DetectSetupParseRegexes(const char *parse_str, DetectParseRegex *detect_parse)
Definition: detect-parse.c:2791
detect-engine-mpm.h
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struct SigMatch_ * next
Definition: detect.h:351
DetectIdRegister
void DetectIdRegister(void)
Registration function for keyword: id.
Definition: detect-id.c:65
DETECT_SM_LIST_MATCH
@ DETECT_SM_LIST_MATCH
Definition: detect.h:111
IPV4_GET_IPID
#define IPV4_GET_IPID(p)
Definition: decode-ipv4.h:129
Signature_::flags
uint32_t flags
Definition: detect.h:594
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Definition: decode.h:437
detect-id.h
Packet_::ip4h
IPV4Hdr * ip4h
Definition: decode.h:545
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:662
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int(* Match)(DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *)
Definition: detect.h:1261
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PrefilterPacketHeaderValue v1
Definition: detect-engine-prefilter-common.h:36
SigMatchCtx_
Used to start a pointer to SigMatch context Should never be dereferenced without casting to something...
Definition: detect.h:342
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Definition: detect-id.h:30
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uint16_t type
Definition: detect.h:348
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Definition: detect-parse.c:127
UTHGenericTest
int UTHGenericTest(Packet **pkt, int numpkts, const char *sigs[], uint32_t sids[], uint32_t *results, int numsigs)
UTHGenericTest: function that perform a generic check taking care of as maximum common unittest eleme...
Definition: util-unittest-helper.c:586
PrefilterSetupPacketHeader
int PrefilterSetupPacketHeader(DetectEngineCtx *de_ctx, SigGroupHead *sgh, int sm_type, void(*Set)(PrefilterPacketHeaderValue *v, void *), bool(*Compare)(PrefilterPacketHeaderValue v, void *), void(*Match)(DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx))
Definition: detect-engine-prefilter-common.c:417
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#define SCMalloc(sz)
Definition: util-mem.h:47
SCLogError
#define SCLogError(...)
Macro used to log ERROR messages.
Definition: util-debug.h:261
DETECT_IPID_MAX
#define DETECT_IPID_MAX
Definition: detect-id.h:28
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#define SCFree(p)
Definition: util-mem.h:61
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bool(* SupportsPrefilter)(const Signature *s)
Definition: detect.h:1280
detect-parse.h
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Signature container.
Definition: detect.h:593
SigMatch_
a single match condition for a signature
Definition: detect.h:347
DETECT_IPID_MIN
#define DETECT_IPID_MIN
Definition: detect-id.h:27
DetectIdFree
void DetectIdFree(DetectEngineCtx *, void *)
this function will free memory associated with DetectIdData
Definition: detect-id.c:215
PrefilterPacketHeaderValue
Definition: detect-engine-prefilter-common.h:23
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:447
detect-engine-prefilter-common.h
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flow-var.h
PKT_IS_IPV4
#define PKT_IS_IPV4(p)
Definition: decode.h:246
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void(* RegisterTests)(void)
Definition: detect.h:1285
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#define SIG_FLAG_REQUIRE_PACKET
Definition: detect.h:246
UTHFreePackets
void UTHFreePackets(Packet **p, int numpkts)
UTHFreePackets: function to release the allocated data from UTHBuildPacket and the packet itself.
Definition: util-unittest-helper.c:471