/* 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 Brian Rectanus * * Implements byte_jump keyword. */ #include "suricata-common.h" #include "debug.h" #include "decode.h" #include "detect.h" #include "detect-parse.h" #include "detect-bytejump.h" #include "detect-content.h" #include "util-byte.h" #include "util-unittest.h" #include "util-debug.h" /** * \brief Regex for parsing our options */ #define PARSE_REGEX "^\\s*" \ "([^\\s,]+\\s*,\\s*[^\\s,]+)" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "(?:\\s*,\\s*((?:multiplier|post_offset)\\s+[^\\s,]+|[^\\s,]+))?" \ "\\s*$" static pcre *parse_regex; static pcre_extra *parse_regex_study; void DetectBytejumpRegisterTests(void); void DetectBytejumpRegister (void) { const char *eb; int eo; int opts = 0; sigmatch_table[DETECT_BYTEJUMP].name = "byte_jump"; sigmatch_table[DETECT_BYTEJUMP].Match = DetectBytejumpMatch; sigmatch_table[DETECT_BYTEJUMP].Setup = DetectBytejumpSetup; sigmatch_table[DETECT_BYTEJUMP].Free = DetectBytejumpFree; sigmatch_table[DETECT_BYTEJUMP].RegisterTests = DetectBytejumpRegisterTests; sigmatch_table[DETECT_BYTEJUMP].flags |= SIGMATCH_PAYLOAD; 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 Byte jump match function * \param det_ctx thread detect engine ctx * \param s signature * \param m byte jump sigmatch * \param payload ptr to the payload * \param payload_len length of the payload * \retval 1 match * \retval 0 no match */ int DetectBytejumpDoMatch(DetectEngineThreadCtx *det_ctx, Signature *s, SigMatch *m, uint8_t *payload, uint32_t payload_len) { SCEnter(); DetectBytejumpData *data = (DetectBytejumpData *)m->ctx; uint8_t *ptr = NULL; uint8_t *jumpptr = ptr; uint32_t len = 0; uint64_t val = 0; int extbytes; if (payload_len == 0) { SCReturnInt(0); } /* Calculate the ptr value for the bytejump and length remaining in * the packet from that point. */ if (data->flags & DETECT_BYTEJUMP_RELATIVE) { ptr = payload + det_ctx->payload_offset; len = payload_len - det_ctx->payload_offset; /* No match if there is no relative base */ if (ptr == NULL || len == 0) { SCReturnInt(0); } ptr += data->offset; len -= data->offset; } else { ptr = payload + data->offset; len = payload_len - data->offset; } /* Verify the to-be-extracted data is within the packet */ if (ptr < payload || data->nbytes > len) { SCLogDebug("Data not within payload " "pkt=%p, ptr=%p, len=%d, nbytes=%d", payload, ptr, len, data->nbytes); SCReturnInt(0); } /* Extract the byte data */ if (data->flags & DETECT_BYTEJUMP_STRING) { extbytes = ByteExtractStringUint64(&val, data->base, data->nbytes, (const char *)ptr); if(extbytes <= 0) { SCLogError(SC_ERR_BYTE_EXTRACT_FAILED,"Error extracting %d bytes " "of string data: %d", data->nbytes, extbytes); SCReturnInt(-1); } } else { int endianness = (data->flags & DETECT_BYTEJUMP_LITTLE) ? BYTE_LITTLE_ENDIAN : BYTE_BIG_ENDIAN; extbytes = ByteExtractUint64(&val, endianness, data->nbytes, ptr); if (extbytes != data->nbytes) { SCLogError(SC_ERR_BYTE_EXTRACT_FAILED,"Error extracting %d bytes " "of numeric data: %d", data->nbytes, extbytes); SCReturnInt(-1); } } //printf("VAL: (%" PRIu64 " x %" PRIu32 ") + %d + %" PRId32 "\n", val, data->multiplier, extbytes, data->post_offset); /* Adjust the jump value based on flags */ val *= data->multiplier; if (data->flags & DETECT_BYTEJUMP_ALIGN) { if ((val % 4) != 0) { val += 4 - (val % 4); } } val += extbytes + data->post_offset; /* Calculate the jump location */ if (data->flags & DETECT_BYTEJUMP_BEGIN) { jumpptr = payload + val; //printf("NEWVAL: payload %p + %ld = %p\n", p->payload, val, jumpptr); } else { jumpptr = ptr + val; //printf("NEWVAL: ptr %p + %ld = %p\n", ptr, val, jumpptr); } /* Validate that the jump location is still in the packet * \todo Should this validate it is still in the *payload*? */ if ((jumpptr < payload) || (jumpptr >= payload + payload_len)) { SCLogDebug("Jump location (%p) is not within " "payload (%p-%p)", jumpptr, payload, payload + payload_len - 1); SCReturnInt(0); } #ifdef DEBUG if (SCLogDebugEnabled()) { uint8_t *sptr = (data->flags & DETECT_BYTEJUMP_BEGIN) ? payload : ptr; SCLogDebug("jumping %" PRId64 " bytes from %p (%08x) to %p (%08x)", val, sptr, (int)(sptr - payload), jumpptr, (int)(jumpptr - payload)); } #endif /* DEBUG */ /* Adjust the detection context to the jump location. */ det_ctx->payload_offset = jumpptr - payload; SCReturnInt(1); } int DetectBytejumpMatch(ThreadVars *t, DetectEngineThreadCtx *det_ctx, Packet *p, Signature *s, SigMatch *m) { DetectBytejumpData *data = (DetectBytejumpData *)m->ctx; uint8_t *ptr = NULL; uint8_t *jumpptr = ptr; uint16_t len = 0; uint64_t val = 0; int extbytes; if (p->payload_len == 0) { return 0; } /* Calculate the ptr value for the bytejump and length remaining in * the packet from that point. */ if (data->flags & DETECT_BYTEJUMP_RELATIVE) { ptr = p->payload + det_ctx->payload_offset; len = p->payload_len - det_ctx->payload_offset; /* No match if there is no relative base */ if (ptr == NULL || len == 0) { return 0; } ptr += data->offset; len -= data->offset; } else { ptr = p->payload + data->offset; len = p->payload_len - data->offset; } /* Verify the to-be-extracted data is within the packet */ if (ptr < p->payload || data->nbytes > len) { SCLogDebug("Data not within packet " "payload=%p, ptr=%p, len=%d, nbytes=%d", p->payload, ptr, len, data->nbytes); return 0; } /* Extract the byte data */ if (data->flags & DETECT_BYTEJUMP_STRING) { extbytes = ByteExtractStringUint64(&val, data->base, data->nbytes, (const char *)ptr); if(extbytes <= 0) { SCLogError(SC_ERR_BYTE_EXTRACT_FAILED,"Error extracting %d bytes " "of string data: %d", data->nbytes, extbytes); return -1; } } else { int endianness = (data->flags & DETECT_BYTEJUMP_LITTLE) ? BYTE_LITTLE_ENDIAN : BYTE_BIG_ENDIAN; extbytes = ByteExtractUint64(&val, endianness, data->nbytes, ptr); if (extbytes != data->nbytes) { SCLogError(SC_ERR_BYTE_EXTRACT_FAILED,"Error extracting %d bytes " "of numeric data: %d", data->nbytes, extbytes); return -1; } } //printf("VAL: (%" PRIu64 " x %" PRIu32 ") + %d + %" PRId32 "\n", val, data->multiplier, extbytes, data->post_offset); /* Adjust the jump value based on flags */ val *= data->multiplier; if (data->flags & DETECT_BYTEJUMP_ALIGN) { if ((val % 4) != 0) { val += 4 - (val % 4); } } val += extbytes + data->post_offset; /* Calculate the jump location */ if (data->flags & DETECT_BYTEJUMP_BEGIN) { jumpptr = p->payload + val; //printf("NEWVAL: payload %p + %ld = %p\n", p->payload, val, jumpptr); } else { jumpptr = ptr + val; //printf("NEWVAL: ptr %p + %ld = %p\n", ptr, val, jumpptr); } /* Validate that the jump location is still in the packet * \todo Should this validate it is still in the *payload*? */ if ((jumpptr < p->payload) || (jumpptr >= p->payload + p->payload_len)) { SCLogDebug("Jump location (%p) is not within " "packet (%p-%p)", jumpptr, p->payload, p->payload + p->payload_len - 1); return 0; } #ifdef DEBUG if (SCLogDebugEnabled()) { uint8_t *sptr = (data->flags & DETECT_BYTEJUMP_BEGIN) ? p->payload : ptr; SCLogDebug("jumping %" PRId64 " bytes from %p (%08x) to %p (%08x)", val, sptr, (int)(sptr - p->payload), jumpptr, (int)(jumpptr - p->payload)); } #endif /* DEBUG */ /* Adjust the detection context to the jump location. */ det_ctx->payload_offset = jumpptr - p->payload; return 1; } DetectBytejumpData *DetectBytejumpParse(char *optstr) { DetectBytejumpData *data = NULL; char *args[10] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }; #define MAX_SUBSTRINGS 30 int ret = 0, res = 0; int ov[MAX_SUBSTRINGS]; int numargs = 0; int i = 0; uint32_t nbytes; char *str_ptr; char *end_ptr; /* Execute the regex and populate args with captures. */ ret = pcre_exec(parse_regex, parse_regex_study, optstr, strlen(optstr), 0, 0, ov, MAX_SUBSTRINGS); if (ret < 2 || ret > 10) { SCLogError(SC_ERR_PCRE_PARSE,"parse error, ret %" PRId32 ", string \"%s\"", ret, optstr); goto error; } /* The first two arguments are stashed in the first PCRE substring. * This is because byte_jump can take 10 arguments, but PCRE only * supports 9 substrings, sigh. */ res = pcre_get_substring((char *)optstr, ov, MAX_SUBSTRINGS, i + 1, (const char **)&str_ptr); if (res < 0) { SCLogError(SC_ERR_PCRE_GET_SUBSTRING,"pcre_get_substring failed " "for arg %d", i + 1); goto error; } /* Break up first substring into two parameters * * NOTE: Because of this, we cannot free args[1] as it is part of args[0], * and *yes* this *is* ugly. */ end_ptr = str_ptr; while (!(isspace(*end_ptr) || (*end_ptr == ','))) end_ptr++; *(end_ptr++) = '\0'; args[0] = str_ptr; numargs++; str_ptr = end_ptr; while (isspace(*str_ptr) || (*str_ptr == ',')) str_ptr++; end_ptr = str_ptr; while (!(isspace(*end_ptr) || (*end_ptr == ',')) && (*end_ptr != '\0')) end_ptr++; *(end_ptr++) = '\0'; args[1] = str_ptr; numargs++; /* The remaining args are directly from PCRE substrings */ for (i = 1; i < (ret - 1); i++) { res = pcre_get_substring((char *)optstr, ov, MAX_SUBSTRINGS, i + 1, (const char **)&str_ptr); if (res < 0) { SCLogError(SC_ERR_PCRE_GET_SUBSTRING,"pcre_get_substring failed for arg %d", i + 1); goto error; } args[i+1] = str_ptr; numargs++; } /* Initialize the data */ data = SCMalloc(sizeof(DetectBytejumpData)); if (data == NULL) { SCLogError(SC_ERR_MEM_ALLOC,"malloc failed %s", strerror(errno)); goto error; } data->base = DETECT_BYTEJUMP_BASE_UNSET; data->flags = 0; data->multiplier = 1; data->post_offset = 0; /* * The first two options are required and positional. The * remaining arguments are flags and are not positional. */ /* Number of bytes */ if (ByteExtractStringUint32(&nbytes, 10, strlen(args[0]), args[0]) <= 0) { SCLogError(SC_ERR_INVALID_VALUE, "Malformed number of bytes: %s", optstr); goto error; } /* Offset */ if (ByteExtractStringInt32(&data->offset, 0, strlen(args[1]), args[1]) <= 0) { SCLogError(SC_ERR_INVALID_VALUE, "Malformed offset: %s", optstr); goto error; } /* The remaining options are flags. */ /** \todo Error on dups? */ for (i = 2; i < numargs; i++) { if (strcmp("relative", args[i]) == 0) { data->flags |= DETECT_BYTEJUMP_RELATIVE; } else if (strcasecmp("string", args[i]) == 0) { data->flags |= DETECT_BYTEJUMP_STRING; } else if (strcasecmp("dec", args[i]) == 0) { data->base |= DETECT_BYTEJUMP_BASE_DEC; } else if (strcasecmp("hex", args[i]) == 0) { data->base |= DETECT_BYTEJUMP_BASE_HEX; } else if (strcasecmp("oct", args[i]) == 0) { data->base |= DETECT_BYTEJUMP_BASE_OCT; } else if (strcasecmp("big", args[i]) == 0) { if (data->flags & DETECT_BYTEJUMP_LITTLE) { data->flags ^= DETECT_BYTEJUMP_LITTLE; } } else if (strcasecmp("little", args[i]) == 0) { data->flags |= DETECT_BYTEJUMP_LITTLE; } else if (strcasecmp("from_beginning", args[i]) == 0) { data->flags |= DETECT_BYTEJUMP_BEGIN; } else if (strcasecmp("align", args[i]) == 0) { data->flags |= DETECT_BYTEJUMP_ALIGN; } else if (strncasecmp("multiplier ", args[i], 11) == 0) { if (ByteExtractStringUint32(&data->multiplier, 10, strlen(args[i]) - 11, args[i] + 11) <= 0) { SCLogError(SC_ERR_INVALID_VALUE, "Malformed multiplier: %s", optstr); goto error; } } else if (strncasecmp("post_offset ", args[i], 12) == 0) { if (ByteExtractStringInt32(&data->post_offset, 10, strlen(args[i]) - 12, args[i] + 12) <= 0) { SCLogError(SC_ERR_INVALID_VALUE, "Malformed post_offset: %s", optstr); goto error; } } else { SCLogError(SC_ERR_INVALID_VALUE, "Unknown option: \"%s\"", args[i]); goto error; } } if (data->flags & DETECT_BYTEJUMP_STRING) { /* 23 - This is the largest string (octal, with a zero prefix) that * will not overflow uint64_t. The only way this length * could be over 23 and still not overflow is if it were zero * prefixed and we only support 1 byte of zero prefix for octal. * * "01777777777777777777777" = 0xffffffffffffffff */ if (nbytes > 23) { SCLogError(SC_ERR_INVALID_VALUE, "Cannot test more than 23 bytes " "with \"string\": %s", optstr); goto error; } } else { if (nbytes > 8) { SCLogError(SC_ERR_INVALID_VALUE, "Cannot test more than 8 bytes " "without \"string\": %s\n", optstr); goto error; } if (data->base != DETECT_BYTEJUMP_BASE_UNSET) { SCLogError(SC_ERR_INVALID_VALUE, "Cannot use a base " "without \"string\": %s", optstr); goto error; } } /* This is max 23 so it will fit in a byte (see above) */ data->nbytes = (uint8_t)nbytes; for (i = 0; i < numargs; i++){ if (i == 1) continue; /* args[1] is part of args[0] */ if (args[i] != NULL) SCFree(args[i]); } return data; error: for (i = 0; i < numargs; i++){ if (i == 1) continue; /* args[1] is part of args[0] */ if (args[i] != NULL) SCFree(args[i]); } if (data != NULL) DetectBytejumpFree(data); return NULL; } int DetectBytejumpSetup(DetectEngineCtx *de_ctx, Signature *s, char *optstr) { DetectBytejumpData *data = NULL; SigMatch *sm = NULL; data = DetectBytejumpParse(optstr); if (data == NULL) goto error; if (data->flags & DETECT_BYTEJUMP_RELATIVE) { /** Search for the first previous DetectContent * SigMatch (it can be the same as this one) */ SigMatch *pm = DetectContentGetLastPattern(s->pmatch_tail); if (pm == NULL) { SCLogError(SC_ERR_BYTEJUMP_MISSING_CONTENT, "relative bytejump match needs a previous content option"); goto error; } DetectContentData *cd = (DetectContentData *)pm->ctx; cd->flags |= DETECT_CONTENT_RELATIVE_NEXT; } sm = SigMatchAlloc(); if (sm == NULL) goto error; sm->type = DETECT_BYTEJUMP; sm->ctx = (void *)data; SigMatchAppendPayload(s,sm); return 0; error: if (data != NULL) DetectBytejumpFree(data); if (sm != NULL) SCFree(sm); return -1; } /** * \brief this function will free memory associated with DetectBytejumpData * * \param data pointer to DetectBytejumpData */ void DetectBytejumpFree(void *ptr) { DetectBytejumpData *data = (DetectBytejumpData *)ptr; SCFree(data); } /* UNITTESTS */ #ifdef UNITTESTS /** * \test DetectBytejumpTestParse01 is a test to make sure that we return * "something" when given valid bytejump opt */ int DetectBytejumpTestParse01(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse("4,0"); if (data != NULL) { DetectBytejumpFree(data); result = 1; } return result; } /** * \test DetectBytejumpTestParse02 is a test for setting the required opts */ int DetectBytejumpTestParse02(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse("4, 0"); if (data != NULL) { if ( (data->nbytes == 4) && (data->offset == 0) && (data->multiplier == 1) && (data->post_offset == 0) && (data->flags == 0) && (data->base == DETECT_BYTEJUMP_BASE_UNSET)) { result = 1; } DetectBytejumpFree(data); } return result; } /** * \test DetectBytejumpTestParse03 is a test for setting the optional flags */ int DetectBytejumpTestParse03(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse(" 4,0 , relative , little, string, " "dec, align, from_beginning"); if (data != NULL) { if ( (data->nbytes == 4) && (data->offset == 0) && (data->multiplier == 1) && (data->post_offset == 0) && (data->flags == ( DETECT_BYTEJUMP_RELATIVE |DETECT_BYTEJUMP_LITTLE |DETECT_BYTEJUMP_STRING |DETECT_BYTEJUMP_ALIGN |DETECT_BYTEJUMP_BEGIN)) && (data->base == DETECT_BYTEJUMP_BASE_DEC)) { result = 1; } DetectBytejumpFree(data); } return result; } /** * \test DetectBytejumpTestParse04 is a test for setting the optional flags * with parameters * * \todo This fails becuase we can only have 9 captures and there are 10. */ int DetectBytejumpTestParse04(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse(" 4,0 , relative , little, string, " "dec, align, from_beginning , " "multiplier 2 , post_offset -16 "); if (data != NULL) { if ( (data->nbytes == 4) && (data->offset == 0) && (data->multiplier == 2) && (data->post_offset == -16) && (data->flags == ( DETECT_BYTEJUMP_RELATIVE |DETECT_BYTEJUMP_LITTLE |DETECT_BYTEJUMP_ALIGN |DETECT_BYTEJUMP_STRING |DETECT_BYTEJUMP_BEGIN)) && (data->base == DETECT_BYTEJUMP_BASE_DEC)) { result = 1; } DetectBytejumpFree(data); } return result; } /** * \test DetectBytejumpTestParse05 is a test for setting base without string */ int DetectBytejumpTestParse05(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse(" 4,0 , relative , little, dec, " "align, from_beginning"); if (data == NULL) { result = 1; } return result; } /** * \test DetectBytejumpTestParse06 is a test for too many bytes to extract */ int DetectBytejumpTestParse06(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse("9, 0"); if (data == NULL) { result = 1; } return result; } /** * \test DetectBytejumpTestParse07 is a test for too many string bytes to extract */ int DetectBytejumpTestParse07(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse("24, 0, string, dec"); if (data == NULL) { result = 1; } return result; } /** * \test DetectBytejumpTestParse08 is a test for offset too big */ int DetectBytejumpTestParse08(void) { int result = 0; DetectBytejumpData *data = NULL; data = DetectBytejumpParse("4, 0xffffffffffffffff"); if (data == NULL) { result = 1; } return result; } #endif /* UNITTESTS */ /** * \brief this function registers unit tests for DetectBytejump */ void DetectBytejumpRegisterTests(void) { #ifdef UNITTESTS UtRegisterTest("DetectBytejumpTestParse01", DetectBytejumpTestParse01, 1); UtRegisterTest("DetectBytejumpTestParse02", DetectBytejumpTestParse02, 1); UtRegisterTest("DetectBytejumpTestParse03", DetectBytejumpTestParse03, 1); UtRegisterTest("DetectBytejumpTestParse04", DetectBytejumpTestParse04, 1); UtRegisterTest("DetectBytejumpTestParse05", DetectBytejumpTestParse05, 1); UtRegisterTest("DetectBytejumpTestParse06", DetectBytejumpTestParse06, 1); UtRegisterTest("DetectBytejumpTestParse07", DetectBytejumpTestParse07, 1); UtRegisterTest("DetectBytejumpTestParse08", DetectBytejumpTestParse08, 1); #endif /* UNITTESTS */ }