1 /* Copyright (C) 2007-2018 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 * \ingroup httplayer
20 *
21 * @{
22 */
23
24
25 /**
26 * \file
27 *
28 * \author Anoop Saldanha <anoopsaldanha@gmail.com>
29 *
30 * Implements support for the http_user_agent keyword.
31 */
32
33 #include "suricata-common.h"
34 #include "threads.h"
35 #include "decode.h"
36
37 #include "detect.h"
38 #include "detect-parse.h"
39 #include "detect-engine.h"
40 #include "detect-engine-mpm.h"
41 #include "detect-engine-state.h"
42 #include "detect-engine-prefilter.h"
43 #include "detect-content.h"
44 #include "detect-pcre.h"
45
46 #include "flow.h"
47 #include "flow-var.h"
48 #include "flow-util.h"
49
50 #include "util-debug.h"
51 #include "util-unittest.h"
52 #include "util-unittest-helper.h"
53 #include "util-spm.h"
54
55 #include "app-layer.h"
56 #include "app-layer-parser.h"
57
58 #include "app-layer-htp.h"
59 #include "stream-tcp.h"
60 #include "detect-http-ua.h"
61
62 static int DetectHttpUASetup(DetectEngineCtx *, Signature *, const char *);
63 #ifdef UNITTESTS
64 static void DetectHttpUARegisterTests(void);
65 #endif
66 static int g_http_ua_buffer_id = 0;
67 static int DetectHttpUserAgentSetup(DetectEngineCtx *, Signature *, const char *);
68 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
69 const DetectEngineTransforms *transforms,
70 Flow *_f, const uint8_t _flow_flags,
71 void *txv, const int list_id);
72 static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,
73 const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,
74 const int list_id);
75
76 /**
77 * \brief Registers the keyword handlers for the "http_user_agent" keyword.
78 */
DetectHttpUARegister(void)79 void DetectHttpUARegister(void)
80 {
81 /* http_user_agent content modifier */
82 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].name = "http_user_agent";
83 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].desc = "content modifier to match only on the HTTP User-Agent header";
84 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].url = "/rules/http-keywords.html#http-user-agent";
85 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].Setup = DetectHttpUASetup;
86 #ifdef UNITTESTS
87 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].RegisterTests = DetectHttpUARegisterTests;
88 #endif
89 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_NOOPT;
90 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_INFO_CONTENT_MODIFIER;
91 sigmatch_table[DETECT_AL_HTTP_USER_AGENT].alternative = DETECT_HTTP_UA;
92
93 /* http.user_agent sticky buffer */
94 sigmatch_table[DETECT_HTTP_UA].name = "http.user_agent";
95 sigmatch_table[DETECT_HTTP_UA].desc = "sticky buffer to match specifically and only on the HTTP User Agent buffer";
96 sigmatch_table[DETECT_HTTP_UA].url = "/rules/http-keywords.html#http-user-agent";
97 sigmatch_table[DETECT_HTTP_UA].Setup = DetectHttpUserAgentSetup;
98 sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_NOOPT;
99 sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_INFO_STICKY_BUFFER;
100
101 DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP,
102 SIG_FLAG_TOSERVER, HTP_REQUEST_HEADERS,
103 DetectEngineInspectBufferGeneric, GetData);
104
105 DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2,
106 PrefilterGenericMpmRegister, GetData, ALPROTO_HTTP,
107 HTP_REQUEST_HEADERS);
108
109 DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP2, SIG_FLAG_TOSERVER,
110 HTTP2StateDataClient, DetectEngineInspectBufferGeneric, GetData2);
111
112 DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,
113 GetData2, ALPROTO_HTTP2, HTTP2StateDataClient);
114
115 DetectBufferTypeSetDescriptionByName("http_user_agent",
116 "http user agent");
117
118 g_http_ua_buffer_id = DetectBufferTypeGetByName("http_user_agent");
119 }
120
121 /**
122 * \brief The setup function for the http_user_agent keyword for a signature.
123 *
124 * \param de_ctx Pointer to the detection engine context.
125 * \param s Pointer to the signature for the current Signature being
126 * parsed from the rules.
127 * \param m Pointer to the head of the SigMatch for the current rule
128 * being parsed.
129 * \param arg Pointer to the string holding the keyword value.
130 *
131 * \retval 0 On success
132 * \retval -1 On failure
133 */
DetectHttpUASetup(DetectEngineCtx * de_ctx,Signature * s,const char * arg)134 int DetectHttpUASetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
135 {
136 return DetectEngineContentModifierBufferSetup(de_ctx, s, arg,
137 DETECT_AL_HTTP_USER_AGENT,
138 g_http_ua_buffer_id,
139 ALPROTO_HTTP);
140 }
141
142 /**
143 * \brief this function setup the http.user_agent keyword used in the rule
144 *
145 * \param de_ctx Pointer to the Detection Engine Context
146 * \param s Pointer to the Signature to which the current keyword belongs
147 * \param str Should hold an empty string always
148 *
149 * \retval 0 On success
150 */
DetectHttpUserAgentSetup(DetectEngineCtx * de_ctx,Signature * s,const char * str)151 static int DetectHttpUserAgentSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
152 {
153 if (DetectBufferSetActiveList(s, g_http_ua_buffer_id) < 0)
154 return -1;
155 if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)
156 return -1;
157 return 0;
158 }
159
GetData(DetectEngineThreadCtx * det_ctx,const DetectEngineTransforms * transforms,Flow * _f,const uint8_t _flow_flags,void * txv,const int list_id)160 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
161 const DetectEngineTransforms *transforms, Flow *_f,
162 const uint8_t _flow_flags, void *txv, const int list_id)
163 {
164 InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
165 if (buffer->inspect == NULL) {
166 htp_tx_t *tx = (htp_tx_t *)txv;
167
168 if (tx->request_headers == NULL)
169 return NULL;
170
171 htp_header_t *h = (htp_header_t *)htp_table_get_c(tx->request_headers,
172 "User-Agent");
173 if (h == NULL || h->value == NULL) {
174 SCLogDebug("HTTP UA header not present in this request");
175 return NULL;
176 }
177
178 const uint32_t data_len = bstr_len(h->value);
179 const uint8_t *data = bstr_ptr(h->value);
180
181 InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
182 InspectionBufferApplyTransforms(buffer, transforms);
183 }
184
185 return buffer;
186 }
187
GetData2(DetectEngineThreadCtx * det_ctx,const DetectEngineTransforms * transforms,Flow * _f,const uint8_t _flow_flags,void * txv,const int list_id)188 static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,
189 const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,
190 const int list_id)
191 {
192 SCEnter();
193
194 InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
195 if (buffer->inspect == NULL) {
196 uint32_t b_len = 0;
197 const uint8_t *b = NULL;
198
199 if (rs_http2_tx_get_useragent(txv, &b, &b_len) != 1)
200 return NULL;
201 if (b == NULL || b_len == 0)
202 return NULL;
203
204 InspectionBufferSetup(det_ctx, list_id, buffer, b, b_len);
205 InspectionBufferApplyTransforms(buffer, transforms);
206 }
207
208 return buffer;
209 }
210
211 #ifdef UNITTESTS
212 #include "tests/detect-http-user-agent.c"
213 #endif /* UNITTESTS */
214
215 /**
216 * @}
217 */
218