suricata
detect-flowvar.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 Victor Julien <victor@inliniac.net>
22  *
23  * Simple flowvar content match part of the detection engine.
24  */
25 
26 #include "suricata-common.h"
27 #include "decode.h"
28 
29 #include "detect.h"
30 #include "detect-parse.h"
31 
32 #include "detect-content.h"
33 #include "threads.h"
34 #include "flow.h"
35 #include "flow-var.h"
36 #include "pkt-var.h"
37 #include "detect-flowvar.h"
38 
39 #include "util-spm.h"
40 #include "util-var-name.h"
41 #include "util-debug.h"
42 #include "util-print.h"
43 
44 #define PARSE_REGEX "(.*),(.*)"
45 static DetectParseRegex parse_regex;
46 
48  const Signature *, const SigMatchCtx *);
49 static int DetectFlowvarSetup (DetectEngineCtx *, Signature *, const char *);
50 static int DetectFlowvarPostMatch(DetectEngineThreadCtx *det_ctx,
51  Packet *p, const Signature *s, const SigMatchCtx *ctx);
52 static void DetectFlowvarDataFree(DetectEngineCtx *, void *ptr);
53 
55 {
56  sigmatch_table[DETECT_FLOWVAR].name = "flowvar";
58  sigmatch_table[DETECT_FLOWVAR].Setup = DetectFlowvarSetup;
59  sigmatch_table[DETECT_FLOWVAR].Free = DetectFlowvarDataFree;
60 
61  /* post-match for flowvar storage */
62  sigmatch_table[DETECT_FLOWVAR_POSTMATCH].name = "__flowvar__postmatch__";
63  sigmatch_table[DETECT_FLOWVAR_POSTMATCH].Match = DetectFlowvarPostMatch;
65  sigmatch_table[DETECT_FLOWVAR_POSTMATCH].Free = DetectFlowvarDataFree;
66 
67  DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
68 }
69 
70 /**
71  * \brief this function will SCFree memory associated with DetectFlowvarData
72  *
73  * \param cd pointer to DetectCotentData
74  */
75 static void DetectFlowvarDataFree(DetectEngineCtx *de_ctx, void *ptr)
76 {
77  if (ptr == NULL)
78  SCReturn;
79 
81 
82  if (fd->name)
83  SCFree(fd->name);
84  if (fd->content)
85  SCFree(fd->content);
86 
87  SCFree(fd);
88 }
89 
90 /*
91  * returns 0: no match
92  * 1: match
93  * -1: error
94  */
95 
97  const Signature *s, const SigMatchCtx *ctx)
98 {
99  int ret = 0;
101 
102  FlowVar *fv = FlowVarGet(p->flow, fd->idx);
103  if (fv != NULL) {
104  uint8_t *ptr = SpmSearch(fv->data.fv_str.value,
105  fv->data.fv_str.value_len,
106  fd->content, fd->content_len);
107  if (ptr != NULL)
108  ret = 1;
109  }
110 
111  return ret;
112 }
113 
114 static int DetectFlowvarSetup (DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
115 {
116  DetectFlowvarData *fd = NULL;
117  SigMatch *sm = NULL;
118  char varname[64], varcontent[64];
119 #define MAX_SUBSTRINGS 30
120  int ret = 0, res = 0;
121  int ov[MAX_SUBSTRINGS];
122  uint8_t *content = NULL;
123  uint16_t contentlen = 0;
124  uint32_t contentflags = s->init_data->negated ? DETECT_CONTENT_NEGATED : 0;
125 
126  ret = DetectParsePcreExec(&parse_regex, rawstr, 0, 0, ov, MAX_SUBSTRINGS);
127  if (ret != 3) {
128  SCLogError(SC_ERR_PCRE_MATCH, "\"%s\" is not a valid setting for flowvar.", rawstr);
129  return -1;
130  }
131 
132  res = pcre_copy_substring((char *)rawstr, ov, MAX_SUBSTRINGS, 1, varname, sizeof(varname));
133  if (res < 0) {
134  SCLogError(SC_ERR_PCRE_COPY_SUBSTRING, "pcre_copy_substring failed");
135  return -1;
136  }
137 
138  res = pcre_copy_substring((char *)rawstr, ov, MAX_SUBSTRINGS, 2, varcontent, sizeof(varcontent));
139  if (res < 0) {
140  SCLogError(SC_ERR_PCRE_COPY_SUBSTRING, "pcre_copy_substring failed");
141  return -1;
142  }
143 
144  int varcontent_index = 0;
145  if (strlen(varcontent) >= 2) {
146  if (varcontent[0] == '"')
147  varcontent_index++;
148  if (varcontent[strlen(varcontent)-1] == '"')
149  varcontent[strlen(varcontent)-1] = '\0';
150  }
151  SCLogDebug("varcontent %s", &varcontent[varcontent_index]);
152 
153  res = DetectContentDataParse("flowvar", &varcontent[varcontent_index], &content, &contentlen);
154  if (res == -1)
155  goto error;
156 
157  fd = SCMalloc(sizeof(DetectFlowvarData));
158  if (unlikely(fd == NULL))
159  goto error;
160  memset(fd, 0x00, sizeof(*fd));
161 
162  fd->content = SCMalloc(contentlen);
163  if (unlikely(fd->content == NULL))
164  goto error;
165 
166  memcpy(fd->content, content, contentlen);
167  fd->content_len = contentlen;
168  fd->flags = contentflags;
169 
170  fd->name = SCStrdup(varname);
171  if (unlikely(fd->name == NULL))
172  goto error;
174 
175  /* Okay so far so good, lets get this into a SigMatch
176  * and put it in the Signature. */
177  sm = SigMatchAlloc();
178  if (unlikely(sm == NULL))
179  goto error;
180 
181  sm->type = DETECT_FLOWVAR;
182  sm->ctx = (SigMatchCtx *)fd;
183 
185 
186  SCFree(content);
187  return 0;
188 
189 error:
190  if (fd != NULL)
191  DetectFlowvarDataFree(de_ctx, fd);
192  if (sm != NULL)
193  SCFree(sm);
194  if (content != NULL)
195  SCFree(content);
196  return -1;
197 }
198 
199 /** \brief Store flowvar in det_ctx so we can exec it post-match */
201  uint8_t *key, uint16_t key_len,
202  uint8_t *buffer, uint16_t len, int type)
203 {
204  DetectVarList *fs = SCCalloc(1, sizeof(*fs));
205  if (unlikely(fs == NULL))
206  return -1;
207 
208  fs->len = len;
209  fs->type = type;
210  fs->buffer = buffer;
211  fs->key = key;
212  fs->key_len = key_len;
213 
214  fs->next = det_ctx->varlist;
215  det_ctx->varlist = fs;
216  return 0;
217 }
218 
219 /** \brief Store flowvar in det_ctx so we can exec it post-match */
221  uint32_t idx,
222  uint8_t *buffer, uint16_t len, int type)
223 {
224  DetectVarList *fs = det_ctx->varlist;
225 
226  /* first check if we have had a previous match for this idx */
227  for ( ; fs != NULL; fs = fs->next) {
228  if (fs->idx == idx) {
229  /* we're replacing the older store */
230  SCFree(fs->buffer);
231  fs->buffer = NULL;
232  break;
233  }
234  }
235 
236  if (fs == NULL) {
237  fs = SCCalloc(1, sizeof(*fs));
238  if (unlikely(fs == NULL))
239  return -1;
240 
241  fs->idx = idx;
242 
243  fs->next = det_ctx->varlist;
244  det_ctx->varlist = fs;
245  }
246 
247  fs->len = len;
248  fs->type = type;
249  fs->buffer = buffer;
250  return 0;
251 }
252 
253 /** \brief Setup a post-match for flowvar storage
254  * We're piggyback riding the DetectFlowvarData struct
255  */
257 {
258  SigMatch *sm = NULL;
259  DetectFlowvarData *fv = NULL;
260 
261  fv = SCMalloc(sizeof(DetectFlowvarData));
262  if (unlikely(fv == NULL))
263  goto error;
264  memset(fv, 0x00, sizeof(*fv));
265 
266  /* we only need the idx */
267  fv->idx = idx;
268 
269  sm = SigMatchAlloc();
270  if (unlikely(sm == NULL))
271  goto error;
272 
274  sm->ctx = (SigMatchCtx *)fv;
275 
277  return 0;
278 error:
279  if (fv != NULL)
280  DetectFlowvarDataFree(de_ctx, fv);
281  return -1;
282 }
283 
284 /** \internal
285  * \brief post-match func to store flowvars in the flow
286  * \param sm sigmatch containing the idx to store
287  * \retval 1 or -1 in case of error
288  */
289 static int DetectFlowvarPostMatch(
290  DetectEngineThreadCtx *det_ctx,
291  Packet *p, const Signature *s, const SigMatchCtx *ctx)
292 {
293  DetectVarList *fs, *prev;
294  const DetectFlowvarData *fd;
295 
296  if (det_ctx->varlist == NULL)
297  return 1;
298 
299  fd = (const DetectFlowvarData *)ctx;
300 
301  prev = NULL;
302  fs = det_ctx->varlist;
303  while (fs != NULL) {
304  if (fd->idx == 0 || fd->idx == fs->idx) {
305  SCLogDebug("adding to the flow %u:", fs->idx);
306  //PrintRawDataFp(stdout, fs->buffer, fs->len);
307 
308  if (fs->type == DETECT_VAR_TYPE_FLOW_POSTMATCH && p && p->flow) {
309  FlowVarAddIdValue(p->flow, fs->idx, fs->buffer, fs->len);
310  /* memory at fs->buffer is now the responsibility of
311  * the flowvar code. */
312  } else if (fs->type == DETECT_VAR_TYPE_PKT_POSTMATCH && fs->key && p) {
313  /* pkt key/value */
314  if (PktVarAddKeyValue(p, (uint8_t *)fs->key, fs->key_len,
315  (uint8_t *)fs->buffer, fs->len) == -1)
316  {
317  SCFree(fs->key);
318  SCFree(fs->buffer);
319  /* the rest of fs is freed below */
320  }
321  } else if (fs->type == DETECT_VAR_TYPE_PKT_POSTMATCH && p) {
322  if (PktVarAdd(p, fs->idx, fs->buffer, fs->len) == -1) {
323  SCFree(fs->buffer);
324  /* the rest of fs is freed below */
325  }
326  }
327 
328  if (fs == det_ctx->varlist) {
329  det_ctx->varlist = fs->next;
330  SCFree(fs);
331  fs = det_ctx->varlist;
332  } else {
333  prev->next = fs->next;
334  SCFree(fs);
335  fs = prev->next;
336  }
337  } else {
338  prev = fs;
339  fs = fs->next;
340  }
341  }
342  return 1;
343 }
344 
345 /** \brief Handle flowvar candidate list in det_ctx: clean up the list
346  *
347  * Only called from DetectVarProcessList() when varlist is not NULL.
348  */
350 {
352 
353  do {
354  next = fs->next;
355 
356  if (fs->key) {
357  SCFree(fs->key);
358  }
359  SCFree(fs->buffer);
360  SCFree(fs);
361  fs = next;
362  } while (fs != NULL);
363 }
detect-content.h
len
uint8_t len
Definition: app-layer-dnp3.h:2
DetectFlowvarPostMatchSetup
int DetectFlowvarPostMatchSetup(DetectEngineCtx *de_ctx, Signature *s, uint32_t idx)
Setup a post-match for flowvar storage We're piggyback riding the DetectFlowvarData struct.
Definition: detect-flowvar.c:256
DetectVarList_::idx
uint32_t idx
Definition: detect.h:659
DetectVarList_::buffer
uint8_t * buffer
Definition: detect.h:664
SigTableElmt_::Free
void(* Free)(DetectEngineCtx *, void *)
Definition: detect.h:1201
SigTableElmt_::name
const char * name
Definition: detect.h:1211
unlikely
#define unlikely(expr)
Definition: util-optimize.h:35
DetectVarStoreMatch
int DetectVarStoreMatch(DetectEngineThreadCtx *det_ctx, uint32_t idx, uint8_t *buffer, uint16_t len, int type)
Store flowvar in det_ctx so we can exec it post-match.
Definition: detect-flowvar.c:220
SCLogDebug
#define SCLogDebug(...)
Definition: util-debug.h:298
next
struct HtpBodyChunk_ * next
Definition: app-layer-htp.h:0
FlowVarTypeStr::value_len
uint16_t value_len
Definition: flow-var.h:39
DetectVarList_::key_len
uint16_t key_len
Definition: detect.h:661
threads.h
Flow_
Flow data structure.
Definition: flow.h:347
DetectVarList_
Definition: detect.h:658
DetectVarList_::len
uint16_t len
Definition: detect.h:660
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:767
FlowVar_::fv_str
FlowVarTypeStr fv_str
Definition: flow-var.h:57
util-var-name.h
DetectVarProcessListInternal
void DetectVarProcessListInternal(DetectVarList *fs, Flow *f, Packet *p)
Handle flowvar candidate list in det_ctx: clean up the list.
Definition: detect-flowvar.c:349
FlowVar_::data
union FlowVar_::@115 data
DETECT_VAR_TYPE_PKT_POSTMATCH
#define DETECT_VAR_TYPE_PKT_POSTMATCH
Definition: detect.h:654
PktVarAdd
int PktVarAdd(Packet *p, uint32_t id, uint8_t *value, uint16_t size)
add a key-value pktvar to the pkt
Definition: pkt-var.c:86
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1196
DetectEngineThreadCtx_::varlist
DetectVarList * varlist
Definition: detect.h:1126
detect-flowvar.h
DETECT_SM_LIST_POSTMATCH
@ DETECT_SM_LIST_POSTMATCH
Definition: detect.h:98
decode.h
util-debug.h
SC_ERR_PCRE_MATCH
@ SC_ERR_PCRE_MATCH
Definition: util-error.h:32
type
uint8_t type
Definition: decode-icmpv4.h:0
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1010
DETECT_FLOWVAR
@ DETECT_FLOWVAR
Definition: detect-engine-register.h:82
DetectFlowvarData_::flags
uint8_t flags
Definition: detect-flowvar.h:32
res
PoolThreadReserved res
Definition: stream-tcp-private.h:0
DETECT_FLOWVAR_POSTMATCH
@ DETECT_FLOWVAR_POSTMATCH
Definition: detect-engine-register.h:83
DetectSetupParseRegexes
void DetectSetupParseRegexes(const char *parse_str, DetectParseRegex *detect_parse)
Definition: detect-parse.c:2488
SC_ERR_PCRE_COPY_SUBSTRING
@ SC_ERR_PCRE_COPY_SUBSTRING
Definition: util-error.h:358
util-print.h
DetectFlowvarData_
Definition: detect-flowvar.h:27
detect.h
pkt-var.h
DETECT_CONTENT_NEGATED
#define DETECT_CONTENT_NEGATED
Definition: detect-content.h:40
DETECT_SM_LIST_MATCH
@ DETECT_SM_LIST_MATCH
Definition: detect.h:89
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:323
DetectVarList_::next
struct DetectVarList_ * next
Definition: detect.h:666
SCReturn
#define SCReturn
Definition: util-debug.h:302
DetectParsePcreExec
int DetectParsePcreExec(DetectParseRegex *parse_regex, const char *str, int start_offset, int options, int *ovector, int ovector_size)
Definition: detect-parse.c:2418
Packet_
Definition: decode.h:414
DetectFlowvarData_::name
char * name
Definition: detect-flowvar.h:28
FlowVarAddIdValue
void FlowVarAddIdValue(Flow *f, uint32_t idx, uint8_t *value, uint16_t size)
Definition: flow-var.c:113
DetectFlowvarData_::content_len
uint8_t content_len
Definition: detect-flowvar.h:31
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:597
SignatureInitData_::negated
bool negated
Definition: detect.h:485
SigTableElmt_::Match
int(* Match)(DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *)
Definition: detect.h:1179
SigMatchAlloc
SigMatch * SigMatchAlloc(void)
Definition: detect-parse.c:235
DETECT_VAR_TYPE_FLOW_POSTMATCH
#define DETECT_VAR_TYPE_FLOW_POSTMATCH
Definition: detect.h:653
SigMatch_::type
uint8_t type
Definition: detect.h:321
DetectVarList_::type
int type
Definition: detect.h:662
SigMatchCtx_
Used to start a pointer to SigMatch context Should never be dereferenced without casting to something...
Definition: detect.h:315
DetectContentDataParse
int DetectContentDataParse(const char *keyword, const char *contentstr, uint8_t **pstr, uint16_t *plen)
Parse a content string, ie "abc|DE|fgh".
Definition: detect-content.c:82
FlowVarTypeStr::value
uint8_t * value
Definition: flow-var.h:38
Packet_::flow
struct Flow_ * flow
Definition: decode.h:451
suricata-common.h
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:73
DetectParseRegex_
Definition: detect-parse.h:42
DetectFlowvarData_::content
uint8_t * content
Definition: detect-flowvar.h:30
util-spm.h
VarNameStoreSetupAdd
uint32_t VarNameStoreSetupAdd(const char *name, const enum VarTypes type)
add to staging or return existing id if already in there
Definition: util-var-name.c:323
SCLogError
#define SCLogError(err_code,...)
Macro used to log ERROR messages.
Definition: util-debug.h:257
SCStrdup
#define SCStrdup(s)
Definition: util-mem.h:56
SCMalloc
#define SCMalloc(sz)
Definition: util-mem.h:47
DetectFlowvarRegister
void DetectFlowvarRegister(void)
Definition: detect-flowvar.c:54
DetectVarList_::key
uint8_t * key
Definition: detect.h:663
SCFree
#define SCFree(p)
Definition: util-mem.h:61
DetectFlowvarData_::idx
uint32_t idx
Definition: detect-flowvar.h:29
detect-parse.h
Signature_
Signature container.
Definition: detect.h:528
SigMatch_
a single match condition for a signature
Definition: detect.h:320
VAR_TYPE_FLOW_VAR
@ VAR_TYPE_FLOW_VAR
Definition: util-var.h:37
PARSE_REGEX
#define PARSE_REGEX
Definition: detect-flowvar.c:44
DetectVarStoreMatchKeyValue
int DetectVarStoreMatchKeyValue(DetectEngineThreadCtx *det_ctx, uint8_t *key, uint16_t key_len, uint8_t *buffer, uint16_t len, int type)
Store flowvar in det_ctx so we can exec it post-match.
Definition: detect-flowvar.c:200
SpmSearch
#define SpmSearch(text, textlen, needle, needlelen)
Definition: util-spm.h:101
PktVarAddKeyValue
int PktVarAddKeyValue(Packet *p, uint8_t *key, uint16_t ksize, uint8_t *value, uint16_t size)
add a key-value pktvar to the pkt
Definition: pkt-var.c:56
FlowVarGet
FlowVar * FlowVarGet(Flow *f, uint32_t idx)
get the flowvar with index 'idx' from the flow
Definition: flow-var.c:78
flow.h
SCCalloc
#define SCCalloc(nm, sz)
Definition: util-mem.h:53
flow-var.h
FlowVar_
Definition: flow-var.h:48
DetectFlowvarMatch
int DetectFlowvarMatch(DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *)
Definition: detect-flowvar.c:96
SigMatchAppendSMToList
void SigMatchAppendSMToList(Signature *s, SigMatch *new, int list)
Append a SigMatch to the list type.
Definition: detect-parse.c:349
MAX_SUBSTRINGS
#define MAX_SUBSTRINGS