suricata
detect-pktvar.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  * Implements the pktvar keyword
24  */
25 
26 #include "suricata-common.h"
27 #include "decode.h"
28 
29 #include "detect.h"
30 #include "detect-parse.h"
31 
32 #include "threads.h"
33 #include "pkt-var.h"
34 #include "detect-pktvar.h"
35 #include "detect-content.h"
36 #include "util-spm.h"
37 #include "util-debug.h"
38 #include "util-var-name.h"
39 
40 #define PARSE_REGEX "(.*),(.*)"
41 static DetectParseRegex parse_regex;
42 
43 static int DetectPktvarMatch (DetectEngineThreadCtx *, Packet *,
44  const Signature *, const SigMatchCtx *);
45 static int DetectPktvarSetup (DetectEngineCtx *, Signature *, const char *);
46 static void DetectPktvarFree(DetectEngineCtx *, void *data);
47 
49 {
50  sigmatch_table[DETECT_PKTVAR].name = "pktvar";
51  sigmatch_table[DETECT_PKTVAR].Match = DetectPktvarMatch;
52  sigmatch_table[DETECT_PKTVAR].Setup = DetectPktvarSetup;
53  sigmatch_table[DETECT_PKTVAR].Free = DetectPktvarFree;
54 
55  DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
56 }
57 
58 /*
59  * returns 0: no match
60  * 1: match
61  * -1: error
62  */
63 
64 static int DetectPktvarMatch (DetectEngineThreadCtx *det_ctx, Packet *p,
65  const Signature *s, const SigMatchCtx *ctx)
66 {
67  int ret = 0;
68  const DetectPktvarData *pd = (const DetectPktvarData *)ctx;
69 
70  PktVar *pv = PktVarGet(p, pd->id);
71  if (pv != NULL) {
72  uint8_t *ptr = SpmSearch(pv->value, pv->value_len, pd->content, pd->content_len);
73  if (ptr != NULL)
74  ret = 1;
75  }
76 
77  return ret;
78 }
79 
80 static void DetectPktvarFree(DetectEngineCtx *de_ctx, void *ptr)
81 {
82  DetectPktvarData *data = ptr;
83  if (data != NULL) {
85  SCFree(data->content);
86  SCFree(data);
87  }
88 }
89 
90 static int DetectPktvarSetup (DetectEngineCtx *de_ctx, Signature *s, const char *rawstr)
91 {
92  char *varname = NULL, *varcontent = NULL;
93  int res = 0;
94  size_t pcre2_len;
95  uint8_t *content = NULL;
96  uint16_t len = 0;
97 
98  pcre2_match_data *match = NULL;
99  int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);
100  if (ret != 3) {
101  SCLogError("\"%s\" is not a valid setting for pktvar.", rawstr);
102  goto error;
103  }
104 
105  const char *str_ptr;
106  res = pcre2_substring_get_bynumber(match, 1, (PCRE2_UCHAR8 **)&str_ptr, &pcre2_len);
107  if (res < 0) {
108  SCLogError("pcre2_substring_get_bynumber failed");
109  goto error;
110  }
111  varname = (char *)str_ptr;
112 
113  res = pcre2_substring_get_bynumber(match, 2, (PCRE2_UCHAR8 **)&str_ptr, &pcre2_len);
114  if (res < 0) {
115  pcre2_substring_free((PCRE2_UCHAR8 *)varname);
116  SCLogError("pcre2_substring_get_bynumber failed");
117  goto error;
118  }
119  varcontent = (char *)str_ptr;
120 
121  SCLogDebug("varname '%s', varcontent '%s'", varname, varcontent);
122 
123  char *parse_content;
124  if (strlen(varcontent) >= 2 && varcontent[0] == '"' &&
125  varcontent[strlen(varcontent) - 1] == '"')
126  {
127  parse_content = varcontent + 1;
128  varcontent[strlen(varcontent) - 1] = '\0';
129  } else {
130  parse_content = varcontent;
131  }
132 
133  ret = DetectContentDataParse("pktvar", parse_content, &content, &len);
134  if (ret == -1 || content == NULL) {
135  pcre2_substring_free((PCRE2_UCHAR8 *)varname);
136  pcre2_substring_free((PCRE2_UCHAR8 *)varcontent);
137  goto error;
138  }
139  pcre2_substring_free((PCRE2_UCHAR8 *)varcontent);
140 
141  DetectPktvarData *cd = SCCalloc(1, sizeof(DetectPktvarData));
142  if (unlikely(cd == NULL)) {
143  pcre2_substring_free((PCRE2_UCHAR8 *)varname);
144  SCFree(content);
145  goto error;
146  }
147 
148  cd->content = content;
149  cd->content_len = len;
150  cd->id = VarNameStoreRegister(varname, VAR_TYPE_PKT_VAR);
151  pcre2_substring_free((PCRE2_UCHAR8 *)varname);
152 
153  /* Okay so far so good, lets get this into a SigMatch
154  * and put it in the Signature. */
156  NULL) {
157  goto error;
158  }
159 
160  pcre2_match_data_free(match);
161  return 0;
162 
163 error:
164  if (match) {
165  pcre2_match_data_free(match);
166  }
167  return -1;
168 }
detect-content.h
PktVarGet
PktVar * PktVarGet(Packet *p, uint32_t id)
Definition: pkt-var.c:40
len
uint8_t len
Definition: app-layer-dnp3.h:2
SigTableElmt_::Free
void(* Free)(DetectEngineCtx *, void *)
Definition: detect.h:1283
DetectParseRegex
Definition: detect-parse.h:62
SigTableElmt_::name
const char * name
Definition: detect.h:1293
detect-pktvar.h
unlikely
#define unlikely(expr)
Definition: util-optimize.h:35
DetectPktvarData_::id
uint32_t id
Definition: detect-pktvar.h:28
SCLogDebug
#define SCLogDebug(...)
Definition: util-debug.h:269
threads.h
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:836
util-var-name.h
DetectParsePcreExec
int DetectParsePcreExec(DetectParseRegex *parse_regex, pcre2_match_data **match, const char *str, int start_offset, int options)
Definition: detect-parse.c:2674
VarNameStoreRegister
uint32_t VarNameStoreRegister(const char *name, const enum VarTypes type)
Definition: util-var-name.c:155
DetectPktvarData_::content_len
uint16_t content_len
Definition: detect-pktvar.h:29
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1278
DetectPktvarData_::content
uint8_t * content
Definition: detect-pktvar.h:31
decode.h
util-debug.h
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1092
PktVar_::value
uint8_t * value
Definition: decode.h:321
DetectSetupParseRegexes
void DetectSetupParseRegexes(const char *parse_str, DetectParseRegex *detect_parse)
Definition: detect-parse.c:2791
detect.h
pkt-var.h
VarNameStoreUnregister
void VarNameStoreUnregister(const uint32_t id, const enum VarTypes type)
Definition: util-var-name.c:201
DETECT_SM_LIST_MATCH
@ DETECT_SM_LIST_MATCH
Definition: detect.h:111
Packet_
Definition: decode.h:437
SigTableElmt_::Match
int(* Match)(DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *)
Definition: detect.h:1261
PARSE_REGEX
#define PARSE_REGEX
Definition: detect-pktvar.c:40
SigMatchCtx_
Used to start a pointer to SigMatch context Should never be dereferenced without casting to something...
Definition: detect.h:342
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:83
suricata-common.h
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:127
util-spm.h
SCLogError
#define SCLogError(...)
Macro used to log ERROR messages.
Definition: util-debug.h:261
SCFree
#define SCFree(p)
Definition: util-mem.h:61
detect-parse.h
Signature_
Signature container.
Definition: detect.h:593
PktVar_::value_len
uint16_t value_len
Definition: decode.h:319
DetectPktvarRegister
void DetectPktvarRegister(void)
Definition: detect-pktvar.c:48
PktVar_
Definition: decode.h:313
SpmSearch
#define SpmSearch(text, textlen, needle, needlelen)
Definition: util-spm.h:99
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
DetectPktvarData_
Definition: detect-pktvar.h:27
SCCalloc
#define SCCalloc(nm, sz)
Definition: util-mem.h:53
VAR_TYPE_PKT_VAR
@ VAR_TYPE_PKT_VAR
Definition: util-var.h:32
DETECT_PKTVAR
@ DETECT_PKTVAR
Definition: detect-engine-register.h:88