suricata
detect-ftpdata.c
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1 /* Copyright (C) 2017-2020 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 Eric Leblond <eric@regit.org>
22  *
23  * Match on ftp command used to trigger a ftp data transfer
24  */
25 
26 #include "suricata-common.h"
27 #include "util-unittest.h"
28 
29 #include "detect-parse.h"
30 #include "detect-engine.h"
31 #include "detect-engine-state.h"
32 
33 #include "app-layer-ftp.h"
34 
35 #include "detect-ftpdata.h"
36 
37 /**
38  * \brief Regex for parsing our keyword options
39  */
40 #define PARSE_REGEX "^\\s*(stor|retr)\\s*$"
41 static DetectParseRegex parse_regex;
42 
43 /* Prototypes of functions registered in DetectFtpdataRegister below */
44 static int DetectFtpdataMatch(DetectEngineThreadCtx *,
45  Flow *, uint8_t, void *, void *,
46  const Signature *, const SigMatchCtx *);
47 static int DetectFtpdataSetup (DetectEngineCtx *, Signature *, const char *);
48 static void DetectFtpdataFree (DetectEngineCtx *, void *);
49 #ifdef UNITTESTS
50 static void DetectFtpdataRegisterTests (void);
51 #endif
52 static int g_ftpdata_buffer_id = 0;
53 
54 /**
55  * \brief Registration function for ftpcommand: keyword
56  *
57  * This function is called once in the 'lifetime' of the engine.
58  */
60  /* keyword name: this is how the keyword is used in a rule */
61  sigmatch_table[DETECT_FTPDATA].name = "ftpdata_command";
62  /* description: listed in "suricata --list-keywords=all" */
63  sigmatch_table[DETECT_FTPDATA].desc = "match FTP command triggering a FTP data channel";
64  sigmatch_table[DETECT_FTPDATA].url = "/rules/ftp-keywords.html#ftpdata-command";
65  sigmatch_table[DETECT_FTPDATA].AppLayerTxMatch = DetectFtpdataMatch;
66  /* setup function is called during signature parsing, when the ftpcommand
67  * keyword is encountered in the rule */
68  sigmatch_table[DETECT_FTPDATA].Setup = DetectFtpdataSetup;
69  /* free function is called when the detect engine is freed. Normally at
70  * shutdown, but also during rule reloads. */
71  sigmatch_table[DETECT_FTPDATA].Free = DetectFtpdataFree;
72  /* registers unittests into the system */
73 #ifdef UNITTESTS
74  sigmatch_table[DETECT_FTPDATA].RegisterTests = DetectFtpdataRegisterTests;
75 #endif
78 
81  g_ftpdata_buffer_id = DetectBufferTypeGetByName("ftpdata_command");
82 
83  /* set up the PCRE for keyword parsing */
84  DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
85 }
86 
87 /**
88  * \brief This function is used to check matches from the FTP App Layer Parser
89  *
90  * \param t pointer to thread vars
91  * \param det_ctx pointer to the pattern matcher thread
92  * \param p pointer to the current packet
93  * \param m pointer to the sigmatch
94  * \retval 0 no match
95  * \retval 1 match
96  */
97 static int DetectFtpdataMatch(DetectEngineThreadCtx *det_ctx,
98  Flow *f, uint8_t flags,
99  void *state, void *txv,
100  const Signature *s, const SigMatchCtx *m)
101 {
102  const DetectFtpdataData *ftpcommandd = (const DetectFtpdataData *) m;
103  const FtpDataState *ftp_state = (const FtpDataState *)state;
104 
105  if (ftp_state == NULL)
106  return 0;
107 
108  if (ftpcommandd->command == ftp_state->command) {
109  /* Only match if the flow is in the good direction */
110  if ((flags & STREAM_TOSERVER) && (ftpcommandd->command == FTP_COMMAND_RETR)) {
111  return 0;
112  } else if ((flags & STREAM_TOCLIENT) && (ftpcommandd->command == FTP_COMMAND_STOR)) {
113  return 0;
114  }
115  return 1;
116  }
117 
118  return 0;
119 }
120 
121 /**
122  * \brief This function is used to parse ftpcommand options passed via ftpcommand: keyword
123  *
124  * \param ftpcommandstr Pointer to the user provided ftpcommand options
125  *
126  * \retval ftpcommandd pointer to DetectFtpdataData on success
127  * \retval NULL on failure
128  */
129 static DetectFtpdataData *DetectFtpdataParse(const char *ftpcommandstr)
130 {
131  DetectFtpdataData *ftpcommandd = NULL;
132  char arg1[5] = "";
133  size_t pcre2len;
134 
135  int ret = DetectParsePcreExec(&parse_regex, ftpcommandstr, 0, 0);
136  if (ret != 2) {
137  SCLogError(SC_ERR_PCRE_MATCH, "parse error, ret %" PRId32 "", ret);
138  goto error;
139  }
140 
141  pcre2len = sizeof(arg1);
142  int res = pcre2_substring_copy_bynumber(parse_regex.match, 1, (PCRE2_UCHAR8 *)arg1, &pcre2len);
143  if (res < 0) {
144  SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre2_substring_copy_bynumber failed");
145  goto error;
146  }
147  SCLogDebug("Arg1 \"%s\"", arg1);
148 
149  ftpcommandd = SCMalloc(sizeof (DetectFtpdataData));
150  if (unlikely(ftpcommandd == NULL))
151  goto error;
152  if (!strcmp(arg1, "stor")) {
153  ftpcommandd->command = FTP_COMMAND_STOR;
154  } else if (!strcmp(arg1, "retr")) {
155  ftpcommandd->command = FTP_COMMAND_RETR;
156  } else {
157  SCLogError(SC_ERR_NOT_SUPPORTED, "Invalid command value");
158  goto error;
159  }
160 
161  return ftpcommandd;
162 
163 error:
164  if (ftpcommandd)
165  SCFree(ftpcommandd);
166  return NULL;
167 }
168 
169 /**
170  * \brief parse the options from the 'ftpcommand' keyword in the rule into
171  * the Signature data structure.
172  *
173  * \param de_ctx pointer to the Detection Engine Context
174  * \param s pointer to the Current Signature
175  * \param str pointer to the user provided ftpcommand options
176  *
177  * \retval 0 on Success
178  * \retval -1 on Failure
179  */
180 static int DetectFtpdataSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
181 {
183  return -1;
184 
185  DetectFtpdataData *ftpcommandd = DetectFtpdataParse(str);
186  if (ftpcommandd == NULL)
187  return -1;
188 
189  SigMatch *sm = SigMatchAlloc();
190  if (sm == NULL) {
191  DetectFtpdataFree(de_ctx, ftpcommandd);
192  return -1;
193  }
194  sm->type = DETECT_FTPDATA;
195  sm->ctx = (void *)ftpcommandd;
196 
197  SigMatchAppendSMToList(s, sm, g_ftpdata_buffer_id);
198  return 0;
199 }
200 
201 /**
202  * \brief this function will free memory associated with DetectFtpdataData
203  *
204  * \param ptr pointer to DetectFtpdataData
205  */
206 static void DetectFtpdataFree(DetectEngineCtx *de_ctx, void *ptr) {
207  DetectFtpdataData *ftpcommandd = (DetectFtpdataData *)ptr;
208 
209  /* do more specific cleanup here, if needed */
210 
211  SCFree(ftpcommandd);
212 }
213 
214 #ifdef UNITTESTS
215 
216 static int DetectFtpdataParseTest01(void)
217 {
218  DetectFtpdataData *ftpcommandd = DetectFtpdataParse("stor");
219  FAIL_IF_NULL(ftpcommandd);
220  FAIL_IF(!(ftpcommandd->command == FTP_COMMAND_STOR));
221  DetectFtpdataFree(NULL, ftpcommandd);
222  PASS;
223 }
224 
225 static int DetectFtpdataSignatureTest01(void)
226 {
229 
230  Signature *sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (ftpdata_command:stor; sid:1; rev:1;)");
231  FAIL_IF_NULL(sig);
232  sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (ftpdata_command:retr; sid:2; rev:1;)");
233  FAIL_IF_NULL(sig);
234  sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (ftpdata_command:xxx; sid:3; rev:1;)");
235  FAIL_IF_NOT_NULL(sig);
236 
238  PASS;
239 }
240 
241 /**
242  * \brief this function registers unit tests for DetectFtpdata
243  */
244 static void DetectFtpdataRegisterTests(void)
245 {
246  UtRegisterTest("DetectFtpdataParseTest01", DetectFtpdataParseTest01);
247  UtRegisterTest("DetectFtpdataSignatureTest01",
248  DetectFtpdataSignatureTest01);
249 }
250 #endif /* UNITTESTS */
DetectParseRegex::match
pcre2_match_data * match
Definition: detect-parse.h:47
SigTableElmt_::url
const char * url
Definition: detect.h:1238
DetectSignatureSetAppProto
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
Definition: detect-parse.c:1493
detect-engine.h
FAIL_IF_NULL
#define FAIL_IF_NULL(expr)
Fail a test if expression evaluates to NULL.
Definition: util-unittest.h:89
DETECT_FTPDATA
@ DETECT_FTPDATA
Definition: detect-engine-register.h:278
SigTableElmt_::desc
const char * desc
Definition: detect.h:1237
DetectParsePcreExec
int DetectParsePcreExec(DetectParseRegex *parse_regex, const char *str, int start_offset, int options)
Definition: detect-parse.c:2488
PARSE_REGEX
#define PARSE_REGEX
Regex for parsing our keyword options.
Definition: detect-ftpdata.c:40
SigTableElmt_::Free
void(* Free)(DetectEngineCtx *, void *)
Definition: detect.h:1225
DetectParseRegex
Definition: detect-parse.h:44
SigTableElmt_::name
const char * name
Definition: detect.h:1235
unlikely
#define unlikely(expr)
Definition: util-optimize.h:35
UtRegisterTest
void UtRegisterTest(const char *name, int(*TestFn)(void))
Register unit test.
Definition: util-unittest.c:103
SCLogDebug
#define SCLogDebug(...)
Definition: util-debug.h:296
DetectFtpdataData_::command
FtpRequestCommand command
Definition: detect-ftpdata.h:35
SC_ERR_NOT_SUPPORTED
@ SC_ERR_NOT_SUPPORTED
Definition: util-error.h:257
Flow_
Flow data structure.
Definition: flow.h:356
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:784
DetectEngineCtxFree
void DetectEngineCtxFree(DetectEngineCtx *)
Free a DetectEngineCtx::
Definition: detect-engine.c:2445
FtpDataState_::command
FtpRequestCommand command
Definition: app-layer-ftp.h:205
SigTableElmt_::AppLayerTxMatch
int(* AppLayerTxMatch)(DetectEngineThreadCtx *, Flow *, uint8_t flags, void *alstate, void *txv, const Signature *, const SigMatchCtx *)
Definition: detect.h:1206
m
SCMutex m
Definition: flow-hash.h:6
SC_ERR_PCRE_GET_SUBSTRING
@ SC_ERR_PCRE_GET_SUBSTRING
Definition: util-error.h:34
app-layer-ftp.h
detect-ftpdata.h
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:229
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1220
util-unittest.h
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1086
SIG_FLAG_TOSERVER
#define SIG_FLAG_TOSERVER
Definition: detect.h:228
FAIL_IF_NOT_NULL
#define FAIL_IF_NOT_NULL(expr)
Fail a test if expression evaluates to non-NULL.
Definition: util-unittest.h:96
SC_ERR_PCRE_MATCH
@ SC_ERR_PCRE_MATCH
Definition: util-error.h:32
PASS
#define PASS
Pass the test.
Definition: util-unittest.h:105
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1024
DetectSetupParseRegexes
void DetectSetupParseRegexes(const char *parse_str, DetectParseRegex *detect_parse)
Definition: detect-parse.c:2611
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:316
DetectAppLayerInspectEngineRegister2
void DetectAppLayerInspectEngineRegister2(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr2 Callback2, InspectionBufferGetDataPtr GetData)
register inspect engine at start up time
Definition: detect-engine.c:228
detect-engine-state.h
Data structures and function prototypes for keeping state for the detection engine.
SigMatchAlloc
SigMatch * SigMatchAlloc(void)
Definition: detect-parse.c:238
SigMatchCtx_
Used to start a pointer to SigMatch context Should never be dereferenced without casting to something...
Definition: detect.h:308
DetectEngineAppendSig
Signature * DetectEngineAppendSig(DetectEngineCtx *de_ctx, const char *sigstr)
Parse and append a Signature into the Detection Engine Context signature list.
Definition: detect-parse.c:2434
FAIL_IF
#define FAIL_IF(expr)
Fail a test if expression evaluates to true.
Definition: util-unittest.h:71
flags
uint8_t flags
Definition: decode-gre.h:0
suricata-common.h
SigMatch_::type
uint16_t type
Definition: detect.h:314
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:76
SCLogError
#define SCLogError(err_code,...)
Macro used to log ERROR messages.
Definition: util-debug.h:255
ALPROTO_FTPDATA
@ ALPROTO_FTPDATA
Definition: app-layer-protos.h:47
DetectEngineInspectGenericList
uint8_t DetectEngineInspectGenericList(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx, const struct DetectEngineAppInspectionEngine_ *engine, const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv, uint64_t tx_id)
Do the content inspection & validation for a signature.
Definition: detect-engine.c:1951
FtpDataState_
Definition: app-layer-ftp.h:199
SCMalloc
#define SCMalloc(sz)
Definition: util-mem.h:47
str
#define str(s)
Definition: suricata-common.h:280
SCFree
#define SCFree(p)
Definition: util-mem.h:61
DetectFtpdataData_
Definition: detect-ftpdata.h:34
detect-parse.h
Signature_
Signature container.
Definition: detect.h:539
SigMatch_
a single match condition for a signature
Definition: detect.h:313
DetectEngineCtxInit
DetectEngineCtx * DetectEngineCtxInit(void)
Definition: detect-engine.c:2406
FTP_COMMAND_RETR
@ FTP_COMMAND_RETR
Definition: app-layer-ftp.h:70
FTP_COMMAND_STOR
@ FTP_COMMAND_STOR
Definition: app-layer-ftp.h:78
DetectFtpdataRegister
void DetectFtpdataRegister(void)
Registration function for ftpcommand: keyword.
Definition: detect-ftpdata.c:59
SigMatchAppendSMToList
void SigMatchAppendSMToList(Signature *s, SigMatch *new, int list)
Append a SigMatch to the list type.
Definition: detect-parse.c:352
SigTableElmt_::RegisterTests
void(* RegisterTests)(void)
Definition: detect.h:1227