1 /* Copyright (C) 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 Jeff Lucovsky <jeff@lucovsky.org>
22 *
23 * Implements the pcrexform transform keyword with option support
24 */
25
26 #include "suricata-common.h"
27
28 #include "detect.h"
29 #include "detect-engine.h"
30 #include "detect-parse.h"
31 #include "detect-transform-pcrexform.h"
32
33 typedef DetectParseRegex DetectTransformPcrexformData;
34
35 static int DetectTransformPcrexformSetup (DetectEngineCtx *, Signature *, const char *);
36 static void DetectTransformPcrexformFree(DetectEngineCtx *, void *);
37 static void DetectTransformPcrexform(InspectionBuffer *buffer, void *options);
38 #ifdef UNITTESTS
39 void DetectTransformPcrexformRegisterTests (void);
40 #endif
41
DetectTransformPcrexformRegister(void)42 void DetectTransformPcrexformRegister(void)
43 {
44 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].name = "pcrexform";
45 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].desc =
46 "modify buffer via PCRE before inspection";
47 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].url = "/rules/transforms.html#pcre-xform";
48 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].Transform =
49 DetectTransformPcrexform;
50 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].Free =
51 DetectTransformPcrexformFree;
52 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].Setup =
53 DetectTransformPcrexformSetup;
54 #ifdef UNITTESTS
55 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].RegisterTests = DetectTransformPcrexformRegisterTests;
56 #endif
57 sigmatch_table[DETECT_TRANSFORM_PCREXFORM].flags |= SIGMATCH_QUOTES_MANDATORY;
58 }
59
DetectTransformPcrexformFree(DetectEngineCtx * de_ctx,void * ptr)60 static void DetectTransformPcrexformFree(DetectEngineCtx *de_ctx, void *ptr)
61 {
62 if (ptr != NULL) {
63 DetectTransformPcrexformData *pxd = (DetectTransformPcrexformData *) ptr;
64 SCFree(pxd);
65 }
66 }
67 /**
68 * \internal
69 * \brief Apply the pcrexform keyword to the last pattern match
70 * \param det_ctx detection engine ctx
71 * \param s signature
72 * \param regexstr options string
73 * \retval 0 ok
74 * \retval -1 failure
75 */
DetectTransformPcrexformSetup(DetectEngineCtx * de_ctx,Signature * s,const char * regexstr)76 static int DetectTransformPcrexformSetup (DetectEngineCtx *de_ctx, Signature *s, const char *regexstr)
77 {
78 SCEnter();
79
80 // Create pxd from regexstr
81 DetectTransformPcrexformData *pxd = SCCalloc(sizeof(*pxd), 1);
82 if (pxd == NULL) {
83 SCLogDebug("pxd allocation failed");
84 SCReturnInt(-1);
85 }
86
87 if (!DetectSetupParseRegexesOpts(regexstr, pxd, 0)) {
88 SCFree(pxd);
89 SCReturnInt(-1);
90 }
91
92 int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_PCREXFORM, pxd);
93 if (r != 0) {
94 SCFree(pxd);
95 }
96
97 SCReturnInt(r);
98 }
99
DetectTransformPcrexform(InspectionBuffer * buffer,void * options)100 static void DetectTransformPcrexform(InspectionBuffer *buffer, void *options)
101 {
102 const char *input = (const char *)buffer->inspect;
103 const uint32_t input_len = buffer->inspect_len;
104 DetectTransformPcrexformData *pxd = options;
105
106 int ov[MAX_SUBSTRINGS];
107 int ret = DetectParsePcreExecLen(pxd, input, input_len, 0, 0, ov, MAX_SUBSTRINGS);
108
109 if (ret > 0) {
110 const char *str;
111 ret = pcre_get_substring((char *) buffer->inspect, ov,
112 MAX_SUBSTRINGS, ret - 1, &str);
113
114 if (ret >= 0) {
115 InspectionBufferCopy(buffer, (uint8_t *)str, (uint32_t) ret);
116 pcre_free_substring(str);
117 }
118 }
119 }
120
121 #ifdef UNITTESTS
122 #include "tests/detect-transform-pcrexform.c"
123 #endif
124