suricata
detect-classtype.c
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1 /* Copyright (C) 2007-2020 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 Anoop Saldanha <anoopsaldanha@gmail.com>
22  * \author Victor Julien <victor@inliniac.net>
23  *
24  * Implements classtype keyword.
25  */
26 
27 #include "suricata-common.h"
28 #include "decode.h"
29 
30 #include "detect.h"
31 #include "detect-parse.h"
32 #include "detect-engine.h"
33 #include "detect-classtype.h"
35 #include "util-error.h"
36 #include "util-debug.h"
37 #include "util-unittest.h"
38 
39 #define PARSE_REGEX "^\\s*([a-zA-Z][a-zA-Z0-9-_]*)\\s*$"
40 
41 static DetectParseRegex parse_regex;
42 
43 static int DetectClasstypeSetup(DetectEngineCtx *, Signature *, const char *);
44 #ifdef UNITTESTS
45 static void DetectClasstypeRegisterTests(void);
46 #endif
47 
48 /**
49  * \brief Registers the handler functions for the "Classtype" keyword.
50  */
52 {
53  sigmatch_table[DETECT_CLASSTYPE].name = "classtype";
54  sigmatch_table[DETECT_CLASSTYPE].desc = "information about the classification of rules and alerts";
55  sigmatch_table[DETECT_CLASSTYPE].url = "/rules/meta.html#classtype";
56  sigmatch_table[DETECT_CLASSTYPE].Setup = DetectClasstypeSetup;
57 #ifdef UNITTESTS
58  sigmatch_table[DETECT_CLASSTYPE].RegisterTests = DetectClasstypeRegisterTests;
59 #endif
60  DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
61 }
62 
63 /**
64  * \brief Parses the raw string supplied with the "Classtype" keyword.
65  *
66  * \param Pointer to the string to be parsed.
67  *
68  * \retval bool success or failure.
69  */
70 static int DetectClasstypeParseRawString(const char *rawstr, char *out, size_t outsize)
71 {
72  size_t pcre2len;
73 
74  const size_t esize = CLASSTYPE_NAME_MAX_LEN + 8;
75  char e[esize];
76  pcre2_match_data *match = NULL;
77 
78  int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);
79  if (ret < 0) {
80  SCLogError("Invalid Classtype in Signature");
81  goto error;
82  }
83 
84  pcre2len = esize;
85  ret = pcre2_substring_copy_bynumber(match, 1, (PCRE2_UCHAR8 *)e, &pcre2len);
86  if (ret < 0) {
87  SCLogError("pcre2_substring_copy_bynumber failed");
88  goto error;
89  }
90 
91  if (strlen(e) >= CLASSTYPE_NAME_MAX_LEN) {
92  SCLogError("classtype '%s' is too big: max %d", rawstr, CLASSTYPE_NAME_MAX_LEN - 1);
93  goto error;
94  }
95  (void)strlcpy(out, e, outsize);
96 
97  pcre2_match_data_free(match);
98  return 0;
99 
100 error:
101  if (match) {
102  pcre2_match_data_free(match);
103  }
104  return -1;
105 }
106 
107 /**
108  * \brief The setup function that would be called when the Signature parsing
109  * module encounters the "Classtype" keyword.
110  *
111  * \param de_ctx Pointer to the Detection Engine Context.
112  * \param s Pointer the current Signature instance that is being parsed.
113  * \param rawstr Pointer to the argument supplied to the classtype keyword.
114  *
115  * \retval 0 On success
116  * \retval -1 On failure
117  */
118 static int DetectClasstypeSetup(DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
119 {
120  char parsed_ct_name[CLASSTYPE_NAME_MAX_LEN] = "";
121 
122  if ((s->class_id > 0) || (s->class_msg != NULL)) {
124  SCLogError("duplicated 'classtype' "
125  "keyword detected.");
126  return -1;
127  } else {
128  SCLogWarning("duplicated 'classtype' "
129  "keyword detected. Using instance with highest priority");
130  }
131  }
132 
133  if (DetectClasstypeParseRawString(rawstr, parsed_ct_name, sizeof(parsed_ct_name)) < 0) {
134  SCLogError("invalid value for classtype keyword: "
135  "\"%s\"",
136  rawstr);
137  return -1;
138  }
139 
140  bool real_ct = true;
141  SCClassConfClasstype *ct = SCClassConfGetClasstype(parsed_ct_name, de_ctx);
142  if (ct == NULL) {
144  SCLogError("unknown classtype '%s'", parsed_ct_name);
145  return -1;
146  }
147 
148  if (s->id > 0) {
149  SCLogWarning("signature sid:%u uses "
150  "unknown classtype: \"%s\", using default priority %d. "
151  "This message won't be shown again for this classtype",
152  s->id, parsed_ct_name, DETECT_DEFAULT_PRIO);
153  } else if (de_ctx->rule_file != NULL) {
154  SCLogWarning("signature at %s:%u uses "
155  "unknown classtype: \"%s\", using default priority %d. "
156  "This message won't be shown again for this classtype",
157  de_ctx->rule_file, de_ctx->rule_line, parsed_ct_name, DETECT_DEFAULT_PRIO);
158  } else {
159  SCLogWarning("unknown classtype: \"%s\", "
160  "using default priority %d. "
161  "This message won't be shown again for this classtype",
162  parsed_ct_name, DETECT_DEFAULT_PRIO);
163  }
164 
165  char str[256];
166  snprintf(str, sizeof(str),
167  "config classification: %s,Unknown Classtype,%d\n",
168  parsed_ct_name, DETECT_DEFAULT_PRIO);
169 
170  if (SCClassConfAddClasstype(de_ctx, str, 0) < 0)
171  return -1;
172  ct = SCClassConfGetClasstype(parsed_ct_name, de_ctx);
173  if (ct == NULL)
174  return -1;
175  real_ct = false;
176  }
177 
178  /* set prio only if not already explicitly set by 'priority' keyword.
179  * update classtype in sig, but only if it is 'real' (not undefined)
180  * update sigs classtype if its prio is lower (but not undefined)
181  */
182 
183  bool update_ct = false;
185  /* don't touch Signature::prio */
186  update_ct = true;
187  } else if (s->prio == -1) {
188  s->prio = ct->priority;
189  update_ct = true;
190  } else {
191  if (ct->priority < s->prio) {
192  s->prio = ct->priority;
193  update_ct = true;
194  }
195  }
196 
197  if (real_ct && update_ct) {
198  s->class_id = ct->classtype_id;
199  s->class_msg = ct->classtype_desc;
200  }
201  return 0;
202 }
203 
204 #ifdef UNITTESTS
205 
206 /**
207  * \test undefined classtype
208  */
209 static int DetectClasstypeTest01(void)
210 {
213 
215  FAIL_IF_NULL(fd);
217  Signature *s = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
218  "(msg:\"Classtype test\"; "
219  "Classtype:not_available; sid:1;)");
220  FAIL_IF_NULL(s);
221  FAIL_IF_NOT(s->prio == 3);
222 
224  PASS;
225 }
226 
227 /**
228  * \test Check that both valid and invalid classtypes in a rule are handled
229  * properly, with rules containing invalid classtypes being rejected
230  * and the ones containing valid classtypes parsed and returned.
231  */
232 static int DetectClasstypeTest02(void)
233 {
236 
238  FAIL_IF_NULL(fd);
240 
241  Signature *sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
242  "(Classtype:bad-unknown; sid:1;)");
243  FAIL_IF_NULL(sig);
244 
245  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
246  "(Classtype:not-there; sid:2;)");
247  FAIL_IF_NULL(sig);
248 
249  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
250  "(Classtype:Bad-UnkNown; sid:3;)");
251  FAIL_IF_NULL(sig);
252 
253  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
254  "(Classtype:nothing-wrong; sid:4;)");
255  FAIL_IF_NULL(sig);
256 
257  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
258  "(Classtype:attempted_dos; Classtype:bad-unknown; sid:5;)");
259  FAIL_IF_NULL(sig);
260  FAIL_IF_NOT(sig->prio == 2);
261 
262  /* duplicate test */
263  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
264  "(Classtype:nothing-wrong; Classtype:Bad-UnkNown; sid:6;)");
265  FAIL_IF_NULL(sig);
266  FAIL_IF_NOT(sig->prio == 2);
267 
269  PASS;
270 }
271 
272 /**
273  * \test Check that the signatures are assigned priority based on classtype they
274  * are given.
275  */
276 static int DetectClasstypeTest03(void)
277 {
280 
282  FAIL_IF_NULL(fd);
284 
285  Signature *sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
286  "(msg:\"Classtype test\"; Classtype:bad-unknown; priority:1; sid:1;)");
287  FAIL_IF_NULL(sig);
288  FAIL_IF_NOT(sig->prio == 1);
289 
290  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
291  "(msg:\"Classtype test\"; Classtype:unKnoWn; "
292  "priority:3; sid:2;)");
293  FAIL_IF_NULL(sig);
294  FAIL_IF_NOT(sig->prio == 3);
295 
296  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any (msg:\"Classtype test\"; "
297  "Classtype:nothing-wrong; priority:1; sid:3;)");
298  FAIL_IF_NOT(sig->prio == 1);
299 
300  sig = DetectEngineAppendSig(de_ctx, "alert tcp any any -> any any "
301  "(msg:\"Classtype test\"; Classtype:bad-unknown; Classtype:undefined; "
302  "priority:5; sid:4;)");
303  FAIL_IF_NULL(sig);
304  FAIL_IF_NOT(sig->prio == 5);
305 
307  PASS;
308 }
309 
310 /**
311  * \brief This function registers unit tests for Classification Config API.
312  */
313 static void DetectClasstypeRegisterTests(void)
314 {
315  UtRegisterTest("DetectClasstypeTest01", DetectClasstypeTest01);
316  UtRegisterTest("DetectClasstypeTest02", DetectClasstypeTest02);
317  UtRegisterTest("DetectClasstypeTest03", DetectClasstypeTest03);
318 }
319 #endif /* UNITTESTS */
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
SigTableElmt_::desc
const char * desc
Definition: detect.h:1295
DetectParseRegex
Definition: detect-parse.h:62
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const char * name
Definition: detect.h:1293
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char * rule_file
Definition: detect.h:926
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void UtRegisterTest(const char *name, int(*TestFn)(void))
Register unit test.
Definition: util-unittest.c:103
detect-classtype.h
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#define SIG_FLAG_INIT_PRIO_EXPLICIT
Definition: detect.h:290
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main detection engine ctx
Definition: detect.h:836
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void DetectEngineCtxFree(DetectEngineCtx *)
Free a DetectEngineCtx::
Definition: detect-engine.c:2533
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uint32_t init_flags
Definition: detect.h:545
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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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Signature * DetectEngineAppendSig(DetectEngineCtx *, const char *)
Parse and append a Signature into the Detection Engine Context signature list.
Definition: detect-parse.c:2620
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1278
util-unittest.h
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#define FAIL_IF_NOT(expr)
Fail a test if expression evaluates to false.
Definition: util-unittest.h:82
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size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: util-strlcpyu.c:43
decode.h
Signature_::class_id
uint16_t class_id
Definition: detect.h:615
util-debug.h
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#define PASS
Pass the test.
Definition: util-unittest.h:105
util-error.h
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DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
SCClassConfClasstype_
Container for a Classtype from the Classification.config file.
Definition: util-classification-config.h:33
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void DetectSetupParseRegexes(const char *parse_str, DetectParseRegex *detect_parse)
Definition: detect-parse.c:2791
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uint16_t classtype_id
Definition: util-classification-config.h:35
SCClassConfAddClasstype
int SCClassConfAddClasstype(DetectEngineCtx *de_ctx, char *rawstr, uint16_t index)
Parses a line from the classification file and adds it to Classtype hash table in DetectEngineCtx,...
Definition: util-classification-config.c:236
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bool SigMatchStrictEnabled(const enum DetectKeywordId id)
Definition: detect-parse.c:395
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#define SCLogWarning(...)
Macro used to log WARNING messages.
Definition: util-debug.h:249
SCClassConfGetClasstype
SCClassConfClasstype * SCClassConfGetClasstype(const char *ct_name, DetectEngineCtx *de_ctx)
Gets the classtype from the corresponding hash table stored in the Detection Engine Context's class c...
Definition: util-classification-config.c:568
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SignatureInitData * init_data
Definition: detect.h:662
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Definition: detect.h:654
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SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:127
util-classification-config.h
Signature_::prio
int prio
Definition: detect.h:631
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Definition: util-classification-config.h:38
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@ DETECT_CLASSTYPE
Definition: detect-engine-register.h:31
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#define str(s)
Definition: suricata-common.h:291
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#define SCLogError(...)
Macro used to log ERROR messages.
Definition: util-debug.h:261
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#define PARSE_REGEX
Definition: detect-classtype.c:39
Signature_::id
uint32_t id
Definition: detect.h:628
detect-parse.h
Signature_
Signature container.
Definition: detect.h:593
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#define CLASSTYPE_NAME_MAX_LEN
Definition: util-classification-config.h:27
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DetectEngineCtx * DetectEngineCtxInit(void)
Definition: detect-engine.c:2494
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char * classtype_desc
Definition: util-classification-config.h:45
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FILE * SCClassConfGenerateValidDummyClassConfigFD01(void)
Creates a dummy classification file, with all valid Classtypes, for testing purposes.
Definition: util-classification-config.c:594
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#define DETECT_DEFAULT_PRIO
Definition: detect.h:50
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Definition: detect.h:925
DetectClasstypeRegister
void DetectClasstypeRegister(void)
Registers the handler functions for the "Classtype" keyword.
Definition: detect-classtype.c:51
SCClassConfLoadClassificationConfigFile
bool SCClassConfLoadClassificationConfigFile(DetectEngineCtx *de_ctx, FILE *fd)
Loads the Classtype info from the classification.config file.
Definition: util-classification-config.c:531
SigTableElmt_::RegisterTests
void(* RegisterTests)(void)
Definition: detect.h:1285