diff options
Diffstat (limited to 'framework/src/suricata/src/detect-window.c')
| -rw-r--r-- | framework/src/suricata/src/detect-window.c | 367 |
1 files changed, 367 insertions, 0 deletions
diff --git a/framework/src/suricata/src/detect-window.c b/framework/src/suricata/src/detect-window.c new file mode 100644 index 00000000..0fb1afb8 --- /dev/null +++ b/framework/src/suricata/src/detect-window.c @@ -0,0 +1,367 @@ +/* Copyright (C) 2007-2010 Open Information Security Foundation + * + * You can copy, redistribute or modify this Program under the terms of + * the GNU General Public License version 2 as published by the Free + * Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +/** + * \file + * + * \author Pablo Rincon Crespo <pablo.rincon.crespo@gmail.com> + * + * Implements the window keyword. + */ + +#include "suricata-common.h" +#include "debug.h" +#include "decode.h" + +#include "detect.h" +#include "detect-parse.h" + +#include "detect-window.h" +#include "flow.h" +#include "flow-var.h" + +#include "util-debug.h" +#include "util-unittest.h" +#include "util-unittest-helper.h" +#include "util-byte.h" + +/** + * \brief Regex for parsing our window option + */ +#define PARSE_REGEX "^\\s*([!])?\\s*([0-9]{1,9}+)\\s*$" + +static pcre *parse_regex; +static pcre_extra *parse_regex_study; + +int DetectWindowMatch(ThreadVars *, DetectEngineThreadCtx *, Packet *, Signature *, const SigMatchCtx *); +int DetectWindowSetup(DetectEngineCtx *, Signature *, char *); +void DetectWindowRegisterTests(void); +void DetectWindowFree(void *); + +/** + * \brief Registration function for window: keyword + */ +void DetectWindowRegister (void) +{ + sigmatch_table[DETECT_WINDOW].name = "window"; + sigmatch_table[DETECT_WINDOW].desc = "check for a specific TCP window size"; + sigmatch_table[DETECT_WINDOW].url = "https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Header_keywords#Window"; + sigmatch_table[DETECT_WINDOW].Match = DetectWindowMatch; + sigmatch_table[DETECT_WINDOW].Setup = DetectWindowSetup; + sigmatch_table[DETECT_WINDOW].Free = DetectWindowFree; + sigmatch_table[DETECT_WINDOW].RegisterTests = DetectWindowRegisterTests; + + const char *eb; + int eo; + int opts = 0; + + #ifdef WINDOW_DEBUG + printf("detect-window: Registering window rule option\n"); + #endif + + parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL); + if(parse_regex == NULL) + { + SCLogError(SC_ERR_PCRE_COMPILE, "pcre compile of \"%s\" failed at offset %" PRId32 ": %s", PARSE_REGEX, eo, eb); + goto error; + } + + parse_regex_study = pcre_study(parse_regex, 0, &eb); + if(eb != NULL) + { + SCLogError(SC_ERR_PCRE_STUDY, "pcre study failed: %s", eb); + goto error; + } + return; + +error: + /* XXX */ + return; +} + +/** + * \brief This function is used to match the window size on a packet + * + * \param t pointer to thread vars + * \param det_ctx pointer to the pattern matcher thread + * \param p pointer to the current packet + * \param m pointer to the sigmatch that we will cast into DetectWindowData + * + * \retval 0 no match + * \retval 1 match + */ +int DetectWindowMatch(ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, const SigMatchCtx *ctx) +{ + const DetectWindowData *wd = (const DetectWindowData *)ctx; + + if ( !(PKT_IS_TCP(p)) || wd == NULL || PKT_IS_PSEUDOPKT(p)) { + return 0; + } + + if ( (!wd->negated && wd->size == TCP_GET_WINDOW(p)) || (wd->negated && wd->size != TCP_GET_WINDOW(p))) { + return 1; + } + + return 0; +} + +/** + * \brief This function is used to parse window options passed via window: keyword + * + * \param windowstr Pointer to the user provided window options (negation! and size) + * + * \retval wd pointer to DetectWindowData on success + * \retval NULL on failure + */ +DetectWindowData *DetectWindowParse(char *windowstr) +{ + DetectWindowData *wd = NULL; +#define MAX_SUBSTRINGS 30 + int ret = 0, res = 0; + int ov[MAX_SUBSTRINGS]; + + ret = pcre_exec(parse_regex, parse_regex_study, windowstr, strlen(windowstr), 0, 0, ov, MAX_SUBSTRINGS); + if (ret < 1 || ret > 3) { + SCLogError(SC_ERR_PCRE_MATCH, "pcre_exec parse error, ret %" PRId32 ", string %s", ret, windowstr); + goto error; + } + + wd = SCMalloc(sizeof(DetectWindowData)); + if (unlikely(wd == NULL)) + goto error; + + if (ret > 1) { + char copy_str[128] = ""; + res = pcre_copy_substring((char *)windowstr, ov, MAX_SUBSTRINGS, 1, + copy_str, sizeof(copy_str)); + if (res < 0) { + SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_copy_substring failed"); + goto error; + } + + /* Detect if it's negated */ + if (copy_str[0] == '!') + wd->negated = 1; + else + wd->negated = 0; + + if (ret > 2) { + res = pcre_copy_substring((char *)windowstr, ov, MAX_SUBSTRINGS, 2, + copy_str, sizeof(copy_str)); + if (res < 0) { + SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_copy_substring failed"); + goto error; + } + + /* Get the window size if it's a valid value (in packets, we + * should alert if this doesn't happend from decode) */ + if (-1 == ByteExtractStringUint16(&wd->size, 10, 0, copy_str)) { + goto error; + } + } + } + + return wd; + +error: + if (wd != NULL) + DetectWindowFree(wd); + return NULL; + +} + +/** + * \brief this function is used to add the parsed window sizedata into the current signature + * + * \param de_ctx pointer to the Detection Engine Context + * \param s pointer to the Current Signature + * \param windowstr pointer to the user provided window options + * + * \retval 0 on Success + * \retval -1 on Failure + */ +int DetectWindowSetup (DetectEngineCtx *de_ctx, Signature *s, char *windowstr) +{ + DetectWindowData *wd = NULL; + SigMatch *sm = NULL; + + wd = DetectWindowParse(windowstr); + if (wd == NULL) goto error; + + /* Okay so far so good, lets get this into a SigMatch + * and put it in the Signature. */ + sm = SigMatchAlloc(); + if (sm == NULL) + goto error; + + sm->type = DETECT_WINDOW; + sm->ctx = (SigMatchCtx *)wd; + + SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH); + s->flags |= SIG_FLAG_REQUIRE_PACKET; + + return 0; + +error: + if (wd != NULL) DetectWindowFree(wd); + if (sm != NULL) SCFree(sm); + return -1; + +} + +/** + * \brief this function will free memory associated with DetectWindowData + * + * \param wd pointer to DetectWindowData + */ +void DetectWindowFree(void *ptr) +{ + DetectWindowData *wd = (DetectWindowData *)ptr; + SCFree(wd); +} + +#ifdef UNITTESTS /* UNITTESTS */ + +/** + * \test DetectWindowTestParse01 is a test to make sure that we set the size correctly + * when given valid window opt + */ +int DetectWindowTestParse01 (void) +{ + int result = 0; + DetectWindowData *wd = NULL; + wd = DetectWindowParse("35402"); + if (wd != NULL &&wd->size==35402) { + DetectWindowFree(wd); + result = 1; + } + + return result; +} + +/** + * \test DetectWindowTestParse02 is a test for setting the window opt negated + */ +int DetectWindowTestParse02 (void) +{ + int result = 0; + DetectWindowData *wd = NULL; + wd = DetectWindowParse("!35402"); + if (wd != NULL) { + if (wd->negated == 1 && wd->size==35402) { + result = 1; + } else { + printf("expected wd->negated=1 and wd->size=35402\n"); + } + DetectWindowFree(wd); + } + + return result; +} + +/** + * \test DetectWindowTestParse03 is a test to check for an empty value + */ +int DetectWindowTestParse03 (void) +{ + int result = 0; + DetectWindowData *wd = NULL; + wd = DetectWindowParse(""); + if (wd == NULL) { + result = 1; + } else { + printf("expected a NULL pointer (It was an empty string)\n"); + } + DetectWindowFree(wd); + + return result; +} + +/** + * \test DetectWindowTestParse03 is a test to check for a big value + */ +int DetectWindowTestParse04 (void) +{ + int result = 0; + DetectWindowData *wd = NULL; + wd = DetectWindowParse("1235402"); + if (wd != NULL) { + printf("expected a NULL pointer (It was exceeding the MAX window size)\n"); + DetectWindowFree(wd); + }else + result=1; + + return result; +} + +/** + * \test DetectWindowTestPacket01 is a test to check window with constructed packets + */ +int DetectWindowTestPacket01 (void) +{ + int result = 0; + uint8_t *buf = (uint8_t *)"Hi all!"; + uint16_t buflen = strlen((char *)buf); + Packet *p[3]; + p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP); + p[1] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP); + p[2] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_ICMP); + + if (p[0] == NULL || p[1] == NULL ||p[2] == NULL) + goto end; + + /* TCP wwindow = 40 */ + p[0]->tcph->th_win = htons(40); + + /* TCP window = 41 */ + p[1]->tcph->th_win = htons(41); + + char *sigs[2]; + sigs[0]= "alert tcp any any -> any any (msg:\"Testing window 1\"; window:40; sid:1;)"; + sigs[1]= "alert tcp any any -> any any (msg:\"Testing window 2\"; window:41; sid:2;)"; + + uint32_t sid[2] = {1, 2}; + + uint32_t results[3][2] = { + /* packet 0 match sid 1 but should not match sid 2 */ + {1, 0}, + /* packet 1 should not match */ + {0, 1}, + /* packet 2 should not match */ + {0, 0} }; + result = UTHGenericTest(p, 3, sigs, sid, (uint32_t *) results, 2); + + UTHFreePackets(p, 3); +end: + return result; +} + +#endif /* UNITTESTS */ + +/** + * \brief this function registers unit tests for DetectWindow + */ +void DetectWindowRegisterTests(void) +{ + #ifdef UNITTESTS /* UNITTESTS */ + UtRegisterTest("DetectWindowTestParse01", DetectWindowTestParse01, 1); + UtRegisterTest("DetectWindowTestParse02", DetectWindowTestParse02, 1); + UtRegisterTest("DetectWindowTestParse03", DetectWindowTestParse03, 1); + UtRegisterTest("DetectWindowTestParse04", DetectWindowTestParse04, 1); + UtRegisterTest("DetectWindowTestPacket01" , DetectWindowTestPacket01 , 1); + #endif /* UNITTESTS */ +} |