detect-frame.c

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/* Copyright (C) 2021-2022 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
 */
 
#include "suricata-common.h"
#include "threads.h"
#include "decode.h"
#include "detect.h"
 
#include "rust.h"
#include "app-layer-frames.h"
#include "app-layer-parser.h"
 
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-buffer.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-content.h"
#include "detect-engine-content-inspection.h"
#include "detect-frame.h"
 
#include "flow.h"
#include "flow-util.h"
#include "flow-var.h"
 
#include "conf.h"
#include "conf-yaml-loader.h"
 
#include "util-debug.h"
#include "util-spm.h"
#include "util-print.h"
 
static int DetectFrameSetup(DetectEngineCtx *, Signature *, const char *);
 
/**
 * \brief this function setup the sticky buffer used in the rule
 *
 * \param de_ctx Pointer to the Detection Engine Context
 * \param s      Pointer to the Signature to which the current keyword belongs
 * \param str    The frame name. Can be short name 'pdu' or full name 'sip.pdu'
 *
 * \retval 0  On success
 * \retval -1 On failure
 */
static int DetectFrameSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
    char value[256] = "";
    strlcpy(value, str, sizeof(value));
    char buffer_name[512] = ""; // for registering in detect API we always need <proto>.<frame>.
 
    const bool is_tcp = DetectProtoContainsProto(&s->init_data->proto, IPPROTO_TCP);
    const bool is_udp = DetectProtoContainsProto(&s->init_data->proto, IPPROTO_UDP);
    if (!(is_tcp || is_udp)) {
        SCLogError("'frame' keyword only supported for TCP and UDP");
        return -1;
    }
 
    char *dot = strchr(value, '.');
    if (dot != NULL)
        *dot++ = '\0';
    const char *val = dot ? dot : value;
    const char *proto = dot ? value : NULL;
 
    bool is_short = false;
    AppProto keyword_alproto = ALPROTO_UNKNOWN;
    AppProto rule_alproto = s->alproto;
 
    if (proto != NULL) {
        keyword_alproto = StringToAppProto(proto);
        if (!AppProtoIsValid(keyword_alproto)) {
            is_short = true;
            keyword_alproto = rule_alproto;
        }
    } else {
        is_short = true;
        keyword_alproto = rule_alproto;
    }
 
    if (is_short && rule_alproto == ALPROTO_UNKNOWN) {
        SCLogError("rule protocol unknown, can't use shorthand notation for frame '%s'", str);
        return -1;
    } else if (rule_alproto == ALPROTO_UNKNOWN) {
        if (SCDetectSignatureSetAppProto(s, keyword_alproto) < 0)
            return -1;
    } else if (!AppProtoEquals(rule_alproto, keyword_alproto)) {
        SCLogError("frame '%s' protocol '%s' mismatch with rule protocol '%s'", str,
                AppProtoToString(keyword_alproto), AppProtoToString(s->alproto));
        return -1;
    }
 
    const char *frame_str = is_short ? str : val;
    int raw_frame_type = -1;
    if (is_tcp) {
        if (strcmp(frame_str, "stream") == 0) {
            raw_frame_type = FRAME_STREAM_TYPE;
        } else {
            raw_frame_type =
                    AppLayerParserGetFrameIdByName(IPPROTO_TCP, keyword_alproto, frame_str);
        }
    }
    if (is_udp && raw_frame_type < 0)
        raw_frame_type = AppLayerParserGetFrameIdByName(IPPROTO_UDP, keyword_alproto, frame_str);
    if (raw_frame_type < 0) {
        SCLogError("unknown frame '%s' for protocol '%s'", frame_str, proto);
        return -1;
    }
    BUG_ON(raw_frame_type > UINT8_MAX);
 
    if (is_short) {
        snprintf(buffer_name, sizeof(buffer_name), "%s.%s", AppProtoToString(s->alproto), str);
        SCLogDebug("short name: %s", buffer_name);
    } else {
        strlcpy(buffer_name, str, sizeof(buffer_name));
        SCLogDebug("long name: %s", buffer_name);
    }
    // make sure the buffer name is lowercase
    // even if the protocol accepted case-insensitive frame name
    for (size_t i = 0; i < sizeof(buffer_name) && buffer_name[i]; i++) {
        buffer_name[i] = u8_tolower(buffer_name[i]);
    }
 
    uint8_t frame_type = (uint8_t)raw_frame_type;
    /* TODO we can have TS and TC specific frames */
    const int buffer_id = DetectEngineBufferTypeRegisterWithFrameEngines(de_ctx, buffer_name,
            SIG_FLAG_TOSERVER | SIG_FLAG_TOCLIENT, keyword_alproto, frame_type);
    if (buffer_id < 0)
        return -1;
 
    if (SCDetectBufferSetActiveList(de_ctx, s, buffer_id) < 0)
        return -1;
 
    FrameConfigEnable(keyword_alproto, frame_type);
    s->init_data->init_flags |= SIG_FLAG_INIT_FRAME;
    return 0;
}
 
#ifdef UNITTESTS
 
static int DetectFrameTestBadRules(void)
{
    DetectEngineCtx *de_ctx = DetectEngineCtxInit();
    FAIL_IF_NULL(de_ctx);
 
    const char *sigs[] = {
        "alert tcp-pkt any any -> any any (frame:tls.pdu; content:\"a\"; sid:1;)",
        "alert udp any any -> any any (frame:tls.pdu; content:\"a\"; sid:2;)",
        "alert smb any any -> any any (frame:tls.pdu; content:\"a\"; sid:3;)",
        "alert tcp any any -> any any (frame:tls; content:\"a\"; sid:4;)",
        "alert tls any any -> any any (content:\"abc\"; frame:tls.pdu; content:\"a\"; sid:5;)",
        "alert tls any any -> any any (tls.version:1.0; frame:tls.pdu; content:\"a\"; sid:6;)",
        "alert tls any any -> any any (frame:smb1.pdu; content:\"a\"; sid:7;)",
        NULL,
    };
 
    const char **sig = sigs;
    while (*sig) {
        SCLogDebug("sig %s", *sig);
        Signature *s = DetectEngineAppendSig(de_ctx, *sig);
        FAIL_IF_NOT_NULL(s);
        sig++;
    }
 
    DetectEngineCtxFree(de_ctx);
    PASS;
}
 
static void DetectFrameRegisterTests(void)
{
    UtRegisterTest("DetectFrameTestBadRules", DetectFrameTestBadRules);
}
#endif
 
/**
 * \brief Registration function for keyword: ja3_hash
 */
void DetectFrameRegister(void)
{
    sigmatch_table[DETECT_FRAME].name = "frame";
    sigmatch_table[DETECT_FRAME].desc = "sticky buffer for inspecting app-layer frames";
    sigmatch_table[DETECT_FRAME].Setup = DetectFrameSetup;
    sigmatch_table[DETECT_FRAME].flags = SIGMATCH_INFO_STICKY_BUFFER;
#ifdef UNITTESTS
    sigmatch_table[DETECT_FRAME].RegisterTests = DetectFrameRegisterTests;
#endif
}