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108 lines
3.2 KiB
C
108 lines
3.2 KiB
C
/* Copyright (C) 2025 Open Information Security Foundation
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*
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* You can copy, redistribute or modify this Program under the terms of
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* the GNU General Public License version 2 as published by the Free
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* Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include "suricata-common.h"
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#include "detect.h"
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#include "detect-parse.h"
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#include "detect-engine.h"
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#include "detect-engine-buffer.h"
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#include "detect-entropy.h"
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#include "util-var-name.h"
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#include "flow-var.h"
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#include "rust.h"
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static int DetectEntropySetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
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{
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DetectEntropyData *ded = SCDetectEntropyParse(arg);
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if (ded == NULL) {
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goto error;
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}
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int sm_list = DETECT_SM_LIST_PMATCH;
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if (s->init_data->list != DETECT_SM_LIST_NOTSET) {
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/* sticky buffer */
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if (DetectBufferGetActiveList(de_ctx, s) == -1)
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goto error;
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sm_list = s->init_data->list;
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const char *name;
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if (sm_list == DETECT_SM_LIST_BASE64_DATA) {
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name = "base64_data";
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} else {
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name = DetectEngineBufferTypeGetNameById(de_ctx, sm_list);
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if (name == NULL) {
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DEBUG_VALIDATE_BUG_ON(1);
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name = "unknown";
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}
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}
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ded->fv_idx = VarNameStoreRegister(name, VAR_TYPE_FLOW_FLOAT);
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} else {
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ded->fv_idx = VarNameStoreRegister("content", VAR_TYPE_FLOW_FLOAT);
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}
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if (ded->fv_idx == 0) {
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goto error;
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}
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if (SCSigMatchAppendSMToList(de_ctx, s, DETECT_ENTROPY, (SigMatchCtx *)ded, sm_list) != NULL) {
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SCReturnInt(0);
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}
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/* fall through */
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error:
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SCLogDebug("error during entropy setup");
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if (ded != NULL) {
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SCDetectEntropyFree(ded);
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}
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SCReturnInt(-1);
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}
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static void DetectEntropyFree(DetectEngineCtx *de_ctx, void *ptr)
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{
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if (ptr) {
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DetectEntropyData *ded = (DetectEntropyData *)ptr;
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VarNameStoreUnregister(ded->fv_idx, VAR_TYPE_FLOW_FLOAT);
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SCDetectEntropyFree(ptr);
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}
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}
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bool DetectEntropyDoMatch(DetectEngineThreadCtx *det_ctx, const Signature *s,
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const SigMatchCtx *ctx, Flow *flow, const uint8_t *buffer, const uint32_t buffer_len)
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{
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double entropy = -1.0;
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bool rc = SCDetectEntropyMatch(buffer, buffer_len, (const DetectEntropyData *)ctx, &entropy);
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if (flow && entropy != -1.0) {
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DetectEntropyData *ded = (DetectEntropyData *)ctx;
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FlowVarAddFloat(flow, ded->fv_idx, entropy);
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}
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return rc;
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}
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void DetectEntropyRegister(void)
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{
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sigmatch_table[DETECT_ENTROPY].name = "entropy";
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sigmatch_table[DETECT_ENTROPY].desc = "calculate entropy";
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sigmatch_table[DETECT_ENTROPY].url = "/rules/payload-keywords.html#entropy";
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sigmatch_table[DETECT_ENTROPY].Free = DetectEntropyFree;
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sigmatch_table[DETECT_ENTROPY].Setup = DetectEntropySetup;
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}
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