From 6100a7f610cd4415cd94847dd455823a9a569355 Mon Sep 17 00:00:00 2001 From: Breno Silva Date: Wed, 21 Oct 2009 22:19:07 -0200 Subject: [PATCH] FragBits Keyword Signed-off-by: Brian Rectanus --- src/Makefile.am | 1 + src/detect-fragbits.c | 520 ++++++++++++++++++++++++++++++++++++++++++ src/detect-fragbits.h | 41 ++++ src/detect.c | 2 + src/detect.h | 1 + 5 files changed, 565 insertions(+) create mode 100644 src/detect-fragbits.c create mode 100644 src/detect-fragbits.h diff --git a/src/Makefile.am b/src/Makefile.am index 574d2eeb3b..c0f26d6adf 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -72,6 +72,7 @@ detect-stream_size.c detect-stream_size.h \ detect-decode-event.c detect-decode-event.h \ detect-ipopts.c detect-ipopts.h \ detect-flags.c detect-flags.h \ +detect-fragbits.c detect-fragbits.h \ detect-noalert.c detect-noalert.h \ detect-csum.c detect-csum.h \ util-print.c util-print.h \ diff --git a/src/detect-fragbits.c b/src/detect-fragbits.c new file mode 100644 index 0000000000..571c609d67 --- /dev/null +++ b/src/detect-fragbits.c @@ -0,0 +1,520 @@ +/* Copyright (c) 2009 Open Information Security Foundation */ + +/** \file + * \author Breno Silva + */ + +#include "eidps-common.h" +#include "eidps.h" +#include "decode.h" +#include "detect.h" +#include "flow-var.h" +#include "decode-events.h" + +#include "detect-fragbits.h" +#include "util-unittest.h" + +/** + * Regex + * fragbits: [!+*](MDR) + */ +#define PARSE_REGEX "^\\s*(?:([\\+\\*!]))?\\s*([MDR]+)" + +/** + * FragBits args[0] *(3) +(2) !(1) + * + */ + +#define MODIFIER_NOT 1 +#define MODIFIER_PLUS 2 +#define MODIFIER_ANY 3 + +static pcre *parse_regex; +static pcre_extra *parse_regex_study; + +static int DetectFragBitsMatch (ThreadVars *, DetectEngineThreadCtx *, Packet *, Signature *, SigMatch *); +static int DetectFragBitsSetup (DetectEngineCtx *, Signature *s, SigMatch *m, char *str); +static void DetectFragBitsFree(void *); + +/** + * \brief Registration function for fragbits: keyword + */ + +void DetectFragBitsRegister (void) { + sigmatch_table[DETECT_FRAGBITS].name = "fragbits"; + sigmatch_table[DETECT_FRAGBITS].Match = DetectFragBitsMatch; + sigmatch_table[DETECT_FRAGBITS].Setup = DetectFragBitsSetup; + sigmatch_table[DETECT_FRAGBITS].Free = DetectFragBitsFree; + sigmatch_table[DETECT_FRAGBITS].RegisterTests = FragBitsRegisterTests; + + const char *eb; + int opts = 0; + int eo; + + parse_regex = pcre_compile(PARSE_REGEX, opts, &eb, &eo, NULL); + if(parse_regex == NULL) + { + printf("pcre compile of \"%s\" failed at offset %" PRId32 ": %s\n", PARSE_REGEX, eo, eb); + goto error; + } + + parse_regex_study = pcre_study(parse_regex, 0, &eb); + if(eb != NULL) + { + printf("pcre study failed: %s\n", eb); + goto error; + } + +error: + return; + +} + +/** + * \internal + * \brief This function is used to match fragbits on a packet with those passed via fragbits: + * + * \param t pointer to thread vars + * \param det_ctx pointer to the pattern matcher thread + * \param p pointer to the current packet + * \param s pointer to the Signature + * \param m pointer to the sigmatch + * + * \retval 0 no match + * \retval 1 match + */ +static int DetectFragBitsMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m) +{ + int ret = 0; + uint16_t fragbits = 0; + DetectFragBitsData *de = (DetectFragBitsData *)m->ctx; + + if(!de || !PKT_IS_IPV4(p) || !p) + return ret; + + if(IPV4_GET_MF(p)) + fragbits |= IPV4_CACHE_MF; + if(IPV4_GET_DF(p)) + fragbits |= IPV4_CACHE_DF; + if(IPV4_GET_RF(p)) + fragbits |= IPV4_CACHE_RF; + + switch(de->modifier) { + case MODIFIER_ANY: + if((fragbits & de->fragbits) > 0) + return 1; + return ret; + case MODIFIER_PLUS: + if(((fragbits & de->fragbits) == de->fragbits) && (((fragbits - de->fragbits) > 0))) + return 1; + return ret; + case MODIFIER_NOT: + if((fragbits & de->fragbits) != de->fragbits) + return 1; + return ret; + default: + if(fragbits == de->fragbits) + return 1; + } + + return ret; +} + +/** + * \internal + * \brief This function is used to parse fragbits options passed via fragbits: keyword + * + * \param rawstr Pointer to the user provided fragbits options + * + * \retval de pointer to DetectFragBitsData on success + * \retval NULL on failure + */ +static DetectFragBitsData *DetectFragBitsParse (char *rawstr) +{ + DetectFragBitsData *de = NULL; +#define MAX_SUBSTRINGS 30 + int ret = 0, found = 0, res = 0; + int ov[MAX_SUBSTRINGS]; + const char *str_ptr = NULL; + char *args[2] = { NULL, NULL}; + char *ptr; + int i; + + ret = pcre_exec(parse_regex, parse_regex_study, rawstr, strlen(rawstr), 0, 0, ov, MAX_SUBSTRINGS); + + if (ret < 1) { + goto error; + } + + for (i = 0; i < (ret - 1); i++) { + + res = pcre_get_substring((char *)rawstr, ov, MAX_SUBSTRINGS,i + 1, &str_ptr); + + if (res < 0) { + goto error; + } + + args[i] = (char *)str_ptr; + } + + if(args[1] == NULL) + goto error; + + de = malloc(sizeof(DetectFragBitsData)); + if (de == NULL) { + printf("DetectFragBitsSetup malloc failed\n"); + goto error; + } + + memset(de,0,sizeof(DetectFragBitsData)); + + /** First parse args[0] */ + + if(args[0]) { + + ptr = args[0]; + + while (*ptr != '\0') { + switch (*ptr) { + case '!': + de->modifier = MODIFIER_NOT; + break; + case '+': + de->modifier = MODIFIER_PLUS; + break; + case '*': + de->modifier = MODIFIER_ANY; + break; + } + ptr++; + } + + } + + /** Second parse first set of fragbits */ + + ptr = args[1]; + + while (*ptr != '\0') { + switch (*ptr) { + case 'M': + case 'm': + de->fragbits |= IPV4_CACHE_MF; + found++; + break; + case 'D': + case 'd': + de->fragbits |= IPV4_CACHE_DF; + found++; + break; + case 'R': + case 'r': + de->fragbits |= IPV4_CACHE_RF; + found++; + break; + default: + found = 0; + break; + } + ptr++; + } + + if(found == 0) + goto error; + + for (i = 0; i < (ret - 1); i++){ + if (args[i] != NULL) free(args[i]); + } + return de; + +error: + for (i = 0; i < (ret - 1); i++){ + if (args[i] != NULL) free(args[i]); + } + if (de) free(de); + return NULL; +} + +/** + * \internal + * \brief this function is used to add the parsed fragbits into the current signature + * + * \param de_ctx pointer to the Detection Engine Context + * \param s pointer to the Current Signature + * \param m pointer to the Current SigMatch + * \param rawstr pointer to the user provided fragbits options + * + * \retval 0 on Success + * \retval -1 on Failure + */ +static int DetectFragBitsSetup (DetectEngineCtx *de_ctx, Signature *s, SigMatch *m, char *rawstr) +{ + DetectFragBitsData *de = NULL; + SigMatch *sm = NULL; + + de = DetectFragBitsParse(rawstr); + if (de == NULL) + goto error; + + sm = SigMatchAlloc(); + if (sm == NULL) + goto error; + + sm->type = DETECT_FRAGBITS; + sm->ctx = (void *)de; + + SigMatchAppend(s,m,sm); + return 0; + +error: + if (de) free(de); + if (sm) free(sm); + return -1; +} + +/** + * \internal + * \brief this function will free memory associated with DetectFragBitsData + * + * \param de pointer to DetectFragBitsData + */ +static void DetectFragBitsFree(void *de_ptr) { + DetectFragBitsData *de = (DetectFragBitsData *)de_ptr; + if(de) free(de); +} + +/* + * ONLY TESTS BELOW THIS COMMENT + */ + +#ifdef UNITTESTS +/** + * \test FragBitsTestParse01 is a test for a valid fragbits value + * + * \retval 1 on succces + * \retval 0 on failure + */ +static int FragBitsTestParse01 (void) { + DetectFragBitsData *de = NULL; + de = DetectFragBitsParse("M"); + if (de && (de->fragbits == IPV4_CACHE_MF) ) { + DetectFragBitsFree(de); + return 1; + } + + return 0; +} + +/** + * \test FragBitsTestParse02 is a test for an invalid fragbits value + * + * \retval 1 on succces + * \retval 0 on failure + */ +static int FragBitsTestParse02 (void) { + DetectFragBitsData *de = NULL; + de = DetectFragBitsParse("G"); + if (de) { + DetectFragBitsFree(de); + return 1; + } + + return 0; +} + +/** + * \test FragBitsTestParse03 test if DONT FRAG is set. Must return success + * + * \retval 1 on success + * \retval 0 on failure + */ +static int FragBitsTestParse03 (void) { + uint8_t raw_eth[] = { + 0x00 ,0x40 ,0x33 ,0xd9 ,0x7c ,0xfd ,0x00 ,0x00, + 0x39 ,0xcf ,0xd9 ,0xcd ,0x08 ,0x00 ,0x45 ,0x00, + 0x01 ,0x13 ,0x9c ,0x5d ,0x40 ,0x00 ,0xf6 ,0x11, + 0x44 ,0xca ,0x97 ,0xa4 ,0x01 ,0x08 ,0x0a ,0x00, + 0x00 ,0x06 ,0x00 ,0x35 ,0x04 ,0x0b ,0x00 ,0xff, + 0x3c ,0x87 ,0x7d ,0x9e ,0x85 ,0x80 ,0x00 ,0x01, + 0x00 ,0x01 ,0x00 ,0x05 ,0x00 ,0x05 ,0x06 ,0x70, + 0x69 ,0x63 ,0x61 ,0x72 ,0x64 ,0x07 ,0x75 ,0x74, + 0x68 ,0x73 ,0x63 ,0x73 ,0x61 ,0x03 ,0x65 ,0x64, + 0x75 ,0x00 ,0x00 ,0x01 ,0x00 ,0x01 ,0xc0 ,0x0c, + 0x00 ,0x01 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10, + 0x00 ,0x04 ,0x81 ,0x6f ,0x1e ,0x1b ,0x07 ,0x75, + 0x74 ,0x68 ,0x73 ,0x63 ,0x73 ,0x61 ,0x03 ,0x65, + 0x64 ,0x75 ,0x00 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x09 ,0x06 ,0x6b ,0x65, + 0x6e ,0x6f ,0x62 ,0x69 ,0xc0 ,0x34 ,0xc0 ,0x34, + 0x00 ,0x02 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10, + 0x00 ,0x07 ,0x04 ,0x6a ,0x69 ,0x6e ,0x6e ,0xc0, + 0x34 ,0xc0 ,0x34 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x0c ,0x04 ,0x64 ,0x6e, + 0x73 ,0x31 ,0x04 ,0x6e ,0x6a ,0x69 ,0x74 ,0xc0, + 0x3c ,0xc0 ,0x34 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x08 ,0x05 ,0x65 ,0x6c, + 0x7a ,0x69 ,0x70 ,0xc0 ,0x34 ,0xc0 ,0x34 ,0x00, + 0x02 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10 ,0x00, + 0x08 ,0x05 ,0x61 ,0x72 ,0x77 ,0x65 ,0x6e ,0xc0, + 0x34 ,0xc0 ,0x4b ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x1a, + 0x06 ,0xc0 ,0x60 ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x1a, + 0x07 ,0xc0 ,0x73 ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x01 ,0x03 ,0x82 ,0x00 ,0x04 ,0x80 ,0xeb ,0xfb, + 0x0a ,0xc0 ,0x8b ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x01, + 0x0b ,0xc0 ,0x9f ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x0b, + 0x51}; + Packet p; + ThreadVars tv; + DecodeThreadVars dtv; + IPV4Hdr ipv4h; + int ret = 0; + DetectFragBitsData *de = NULL; + SigMatch *sm = NULL; + + memset(&tv, 0, sizeof(ThreadVars)); + memset(&p, 0, sizeof(Packet)); + memset(&dtv, 0, sizeof(DecodeThreadVars)); + memset(&ipv4h, 0, sizeof(IPV4Hdr)); + + p.ip4h = &ipv4h; + + FlowInitConfig(FLOW_QUIET); + + DecodeEthernet(&tv, &dtv, &p, raw_eth, sizeof(raw_eth), NULL); + + FlowShutdown(); + + de = DetectFragBitsParse("D"); + + if (de == NULL || (de->fragbits != IPV4_CACHE_DF)) + goto error; + + sm = SigMatchAlloc(); + if (sm == NULL) + goto error; + + sm->type = DETECT_FRAGBITS; + sm->ctx = (void *)de; + + ret = DetectFragBitsMatch(&tv,NULL,&p,NULL,sm); + + if(ret) { + if (de) free(de); + if (sm) free(sm); + return 1; + } + +error: + if (de) free(de); + if (sm) free(sm); + return 0; +} + +/** + * \test FragBitsTestParse04 test if DONT FRAG is not set. Must fails. + * + * \retval 1 on success + * \retval 0 on failure + */ +static int FragBitsTestParse04 (void) { + uint8_t raw_eth[] = { + 0x00 ,0x40 ,0x33 ,0xd9 ,0x7c ,0xfd ,0x00 ,0x00, + 0x39 ,0xcf ,0xd9 ,0xcd ,0x08 ,0x00 ,0x45 ,0x00, + 0x01 ,0x13 ,0x9c ,0x5d ,0x40 ,0x00 ,0xf6 ,0x11, + 0x44 ,0xca ,0x97 ,0xa4 ,0x01 ,0x08 ,0x0a ,0x00, + 0x00 ,0x06 ,0x00 ,0x35 ,0x04 ,0x0b ,0x00 ,0xff, + 0x3c ,0x87 ,0x7d ,0x9e ,0x85 ,0x80 ,0x00 ,0x01, + 0x00 ,0x01 ,0x00 ,0x05 ,0x00 ,0x05 ,0x06 ,0x70, + 0x69 ,0x63 ,0x61 ,0x72 ,0x64 ,0x07 ,0x75 ,0x74, + 0x68 ,0x73 ,0x63 ,0x73 ,0x61 ,0x03 ,0x65 ,0x64, + 0x75 ,0x00 ,0x00 ,0x01 ,0x00 ,0x01 ,0xc0 ,0x0c, + 0x00 ,0x01 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10, + 0x00 ,0x04 ,0x81 ,0x6f ,0x1e ,0x1b ,0x07 ,0x75, + 0x74 ,0x68 ,0x73 ,0x63 ,0x73 ,0x61 ,0x03 ,0x65, + 0x64 ,0x75 ,0x00 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x09 ,0x06 ,0x6b ,0x65, + 0x6e ,0x6f ,0x62 ,0x69 ,0xc0 ,0x34 ,0xc0 ,0x34, + 0x00 ,0x02 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10, + 0x00 ,0x07 ,0x04 ,0x6a ,0x69 ,0x6e ,0x6e ,0xc0, + 0x34 ,0xc0 ,0x34 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x0c ,0x04 ,0x64 ,0x6e, + 0x73 ,0x31 ,0x04 ,0x6e ,0x6a ,0x69 ,0x74 ,0xc0, + 0x3c ,0xc0 ,0x34 ,0x00 ,0x02 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x08 ,0x05 ,0x65 ,0x6c, + 0x7a ,0x69 ,0x70 ,0xc0 ,0x34 ,0xc0 ,0x34 ,0x00, + 0x02 ,0x00 ,0x01 ,0x00 ,0x00 ,0x0e ,0x10 ,0x00, + 0x08 ,0x05 ,0x61 ,0x72 ,0x77 ,0x65 ,0x6e ,0xc0, + 0x34 ,0xc0 ,0x4b ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x1a, + 0x06 ,0xc0 ,0x60 ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x1a, + 0x07 ,0xc0 ,0x73 ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x01 ,0x03 ,0x82 ,0x00 ,0x04 ,0x80 ,0xeb ,0xfb, + 0x0a ,0xc0 ,0x8b ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x01, + 0x0b ,0xc0 ,0x9f ,0x00 ,0x01 ,0x00 ,0x01 ,0x00, + 0x00 ,0x0e ,0x10 ,0x00 ,0x04 ,0x81 ,0x6f ,0x0b, + 0x51}; + Packet p; + ThreadVars tv; + DecodeThreadVars dtv; + IPV4Hdr ipv4h; + int ret = 0; + DetectFragBitsData *de = NULL; + SigMatch *sm = NULL; + + memset(&tv, 0, sizeof(ThreadVars)); + memset(&p, 0, sizeof(Packet)); + memset(&dtv, 0, sizeof(DecodeThreadVars)); + memset(&ipv4h, 0, sizeof(IPV4Hdr)); + + p.ip4h = &ipv4h; + + FlowInitConfig(FLOW_QUIET); + + DecodeEthernet(&tv, &dtv, &p, raw_eth, sizeof(raw_eth), NULL); + + FlowShutdown(); + + de = DetectFragBitsParse("!D"); + + if (de == NULL || (de->fragbits != IPV4_CACHE_DF) || (de->modifier != MODIFIER_NOT)) + goto error; + + sm = SigMatchAlloc(); + if (sm == NULL) + goto error; + + sm->type = DETECT_FRAGBITS; + sm->ctx = (void *)de; + + ret = DetectFragBitsMatch(&tv,NULL,&p,NULL,sm); + + if(ret) { + if (de) free(de); + if (sm) free(sm); + return 1; + } + +error: + if (de) free(de); + if (sm) free(sm); + return 0; +} +#endif /* UNITTESTS */ + +/** + * \brief this function registers unit tests for FragBits + */ +void FragBitsRegisterTests(void) { +#ifdef UNITTESTS + UtRegisterTest("FragBitsTestParse01", FragBitsTestParse01, 1); + UtRegisterTest("FragBitsTestParse02", FragBitsTestParse02, 0); + UtRegisterTest("FragBitsTestParse03", FragBitsTestParse03, 1); + UtRegisterTest("FragBitsTestParse04", FragBitsTestParse04, 0); +#endif /* UNITTESTS */ +} diff --git a/src/detect-fragbits.h b/src/detect-fragbits.h new file mode 100644 index 0000000000..a2bdea5d37 --- /dev/null +++ b/src/detect-fragbits.h @@ -0,0 +1,41 @@ +/* Copyright (c) 2009 Open Information Security Foundation */ + +/** \file + * \author Breno Silva + */ + +#ifndef __DETECT_FRAGBITS_H__ +#define __DETECT_FRAGBITS_H__ + +#include "decode-events.h" +#include "decode-ipv4.h" +#include "decode-tcp.h" + +/** + * \struct DetectFragBitsData_ + * DetectFragBitsData_ is used to store fragbits: input value + */ + +/** + * \typedef DetectFragBitsData + * A typedef for DetectFragBitsData_ + */ + +typedef struct DetectFragBitsData_ { + uint16_t fragbits; /**< TCP fragbits */ + uint8_t modifier; /**< !(1) +(2) *(3) modifiers */ +} DetectFragBitsData; + +/** + * Registration function for fragbits: keyword + */ + +void DetectFragBitsRegister (void); + +/** + * This function registers unit tests for FragBits + */ + +void FragBitsRegisterTests(void); + +#endif /*__DETECT_FRAGBITS_H__ */ diff --git a/src/detect.c b/src/detect.c index fd76f11a65..9c66bd441b 100644 --- a/src/detect.c +++ b/src/detect.c @@ -19,6 +19,7 @@ #include "detect-decode-event.h" #include "detect-ipopts.h" #include "detect-flags.h" +#include "detect-fragbits.h" #include "detect-content.h" #include "detect-uricontent.h" @@ -2589,6 +2590,7 @@ void SigTableSetup(void) { DetectDecodeEventRegister(); DetectIpOptsRegister(); DetectFlagsRegister(); + DetectFragBitsRegister(); DetectCsumRegister(); DetectStreamSizeRegister(); diff --git a/src/detect.h b/src/detect.h index 86204075b3..22d8fae1eb 100644 --- a/src/detect.h +++ b/src/detect.h @@ -435,6 +435,7 @@ enum { DETECT_DECODE_EVENT, DETECT_IPOPTS, DETECT_FLAGS, + DETECT_FRAGBITS, /* make sure this stays last */ DETECT_TBLSIZE,