diff options
Diffstat (limited to 'framework/src/suricata/src/detect-offset.c')
| -rw-r--r-- | framework/src/suricata/src/detect-offset.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/framework/src/suricata/src/detect-offset.c b/framework/src/suricata/src/detect-offset.c new file mode 100644 index 00000000..65372ec0 --- /dev/null +++ b/framework/src/suricata/src/detect-offset.c @@ -0,0 +1,158 @@ +/* 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 Victor Julien <victor@inliniac.net> + * \author Anoop Saldanha <anoopsaldanha@gmail.com> + * + * Implements the offset keyword. + */ + +#include "suricata-common.h" + +#include "decode.h" + +#include "detect.h" +#include "detect-parse.h" +#include "detect-content.h" +#include "detect-uricontent.h" +#include "detect-byte-extract.h" +#include "app-layer.h" + +#include "flow-var.h" + +#include "util-debug.h" + +static int DetectOffsetSetup(DetectEngineCtx *, Signature *, char *); + +void DetectOffsetRegister (void) +{ + sigmatch_table[DETECT_OFFSET].name = "offset"; + sigmatch_table[DETECT_OFFSET].desc = "designate from which byte in the payload will be checked to find a match"; + sigmatch_table[DETECT_OFFSET].url = "https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Payload_keywords#Offset"; + sigmatch_table[DETECT_OFFSET].Match = NULL; + sigmatch_table[DETECT_OFFSET].Setup = DetectOffsetSetup; + sigmatch_table[DETECT_OFFSET].Free = NULL; + sigmatch_table[DETECT_OFFSET].RegisterTests = NULL; + + sigmatch_table[DETECT_OFFSET].flags |= SIGMATCH_PAYLOAD; +} + +int DetectOffsetSetup (DetectEngineCtx *de_ctx, Signature *s, char *offsetstr) +{ + char *str = offsetstr; + char dubbed = 0; + SigMatch *pm = NULL; + int ret = -1; + + /* strip "'s */ + if (offsetstr[0] == '\"' && offsetstr[strlen(offsetstr)-1] == '\"') { + str = SCStrdup(offsetstr+1); + if (unlikely(str == NULL)) + goto end; + str[strlen(offsetstr) - 2] = '\0'; + dubbed = 1; + } + + /* retrive the sm to apply the depth against */ + if (s->list != DETECT_SM_LIST_NOTSET) { + pm = SigMatchGetLastSMFromLists(s, 2, DETECT_CONTENT, s->sm_lists_tail[s->list]); + } else { + pm = SigMatchGetLastSMFromLists(s, 28, + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_PMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_UMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRUDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HCBDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_FILEDATA], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HHDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRHDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HMDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HCDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HSCDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HSMDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HUADMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HHHDMATCH], + DETECT_CONTENT, s->sm_lists_tail[DETECT_SM_LIST_HRHHDMATCH]); + } + if (pm == NULL) { + SCLogError(SC_ERR_OFFSET_MISSING_CONTENT, "offset needs " + "preceding content, uricontent option, http_client_body, " + "http_server_body, http_header option, http_raw_header option, " + "http_method option, http_cookie, http_raw_uri, " + "http_stat_msg, http_stat_code, http_user_agent or " + "file_data/dce_stub_data sticky buffer options"); + goto end; + } + + + /* verify other conditions */ + DetectContentData *cd = (DetectContentData *)pm->ctx; + + if (cd->flags & DETECT_CONTENT_OFFSET) { + SCLogError(SC_ERR_INVALID_SIGNATURE, "can't use multiple offsets for the same content. "); + goto end; + } + if ((cd->flags & DETECT_CONTENT_WITHIN) || (cd->flags & DETECT_CONTENT_DISTANCE)) { + SCLogError(SC_ERR_INVALID_SIGNATURE, "can't use a relative " + "keyword like within/distance with a absolute " + "relative keyword like depth/offset for the same " + "content." ); + goto end; + } + if (cd->flags & DETECT_CONTENT_NEGATED && cd->flags & DETECT_CONTENT_FAST_PATTERN) { + SCLogError(SC_ERR_INVALID_SIGNATURE, "can't have a relative " + "negated keyword set along with a fast_pattern"); + goto end; + } + if (cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) { + SCLogError(SC_ERR_INVALID_SIGNATURE, "can't have a relative " + "keyword set along with a fast_pattern:only;"); + goto end; + } + if (str[0] != '-' && isalpha((unsigned char)str[0])) { + SigMatch *bed_sm = + DetectByteExtractRetrieveSMVar(str, s); + if (bed_sm == NULL) { + SCLogError(SC_ERR_INVALID_SIGNATURE, "unknown byte_extract var " + "seen in offset - %s\n", str); + goto end; + } + cd->offset = ((DetectByteExtractData *)bed_sm->ctx)->local_id; + cd->flags |= DETECT_CONTENT_OFFSET_BE; + } else { + cd->offset = (uint32_t)atoi(str); + if (cd->depth != 0) { + if (cd->depth < cd->content_len) { + SCLogDebug("depth increased to %"PRIu32" to match pattern len", + cd->content_len); + cd->depth = cd->content_len; + } + /* Updating the depth as is relative to the offset */ + cd->depth += cd->offset; + } + } + cd->flags |= DETECT_CONTENT_OFFSET; + + ret = 0; + end: + if (dubbed) + SCFree(str); + return ret; +} + |