/* Copyright (C) 2019-2021 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 Henrik Kramshoej * * VXLAN tunneling scheme decoder. * * This implementation is based on the following specification doc: * https://tools.ietf.org/html/rfc7348 */ #include "suricata-common.h" #include "decode.h" #include "decode-vxlan.h" #include "decode-events.h" #include "detect.h" #include "detect-engine-port.h" #include "flow.h" #include "util-validate.h" #include "util-unittest.h" #include "util-debug.h" #define VXLAN_HEADER_LEN sizeof(VXLANHeader) #define VXLAN_MAX_PORTS 4 #define VXLAN_UNSET_PORT -1 #define VXLAN_DEFAULT_PORT 4789 #define VXLAN_DEFAULT_PORT_S "4789" typedef enum { VXLAN_RES_CHECK_STRICT = 0, VXLAN_RES_CHECK_PERMISSIVE, } VXLANReservedCheckMode; static bool g_vxlan_enabled = true; static int g_vxlan_ports_idx = 0; static int g_vxlan_ports[VXLAN_MAX_PORTS] = { VXLAN_DEFAULT_PORT, VXLAN_UNSET_PORT, VXLAN_UNSET_PORT, VXLAN_UNSET_PORT }; static VXLANReservedCheckMode g_vxlan_reserved_check_mode = VXLAN_RES_CHECK_STRICT; typedef struct VXLANHeader_ { uint8_t flags[2]; uint16_t gdp; uint8_t vni[3]; uint8_t res; } VXLANHeader; bool DecodeVXLANEnabledForPort(const uint16_t dp) { SCLogDebug("checking dest port %u against ports %d %d %d %d", dp, g_vxlan_ports[0], g_vxlan_ports[1], g_vxlan_ports[2], g_vxlan_ports[3]); if (g_vxlan_enabled) { for (int i = 0; i < g_vxlan_ports_idx; i++) { if (g_vxlan_ports[i] == VXLAN_UNSET_PORT) return false; /* RFC 7348: VXLAN identification is based on destination port only */ if (g_vxlan_ports[i] == (const int)dp) return true; } } return false; } static void DecodeVXLANConfigPorts(const char *pstr) { SCLogDebug("parsing \'%s\'", pstr); DetectPort *head = NULL; DetectPortParse(NULL, &head, pstr); g_vxlan_ports_idx = 0; for (DetectPort *p = head; p != NULL; p = p->next) { if (g_vxlan_ports_idx >= VXLAN_MAX_PORTS) { SCLogWarning("more than %d VXLAN ports defined", VXLAN_MAX_PORTS); break; } g_vxlan_ports[g_vxlan_ports_idx++] = (int)p->port; } DetectPortCleanupList(NULL, head); } void DecodeVXLANConfig(void) { int enabled = 0; if (SCConfGetBool("decoder.vxlan.enabled", &enabled) == 1) { if (enabled) { g_vxlan_enabled = true; } else { g_vxlan_enabled = false; } } if (g_vxlan_enabled) { SCConfNode *node = SCConfGetNode("decoder.vxlan.ports"); if (node && node->val) { DecodeVXLANConfigPorts(node->val); } else { DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); } node = SCConfGetNode("decoder.vxlan.reserved-bits-check"); if (node && node->val) { if (strcasecmp(node->val, "strict") == 0) { g_vxlan_reserved_check_mode = VXLAN_RES_CHECK_STRICT; } else if (strcasecmp(node->val, "permissive") == 0) { g_vxlan_reserved_check_mode = VXLAN_RES_CHECK_PERMISSIVE; } else { SCLogWarning( "Invalid VXLAN reserved-bits-check mode '%s', using 'strict'", node->val); g_vxlan_reserved_check_mode = VXLAN_RES_CHECK_STRICT; } } } } /** \param pkt payload data directly above UDP header * \param len length in bytes of pkt * * \note p->flow is not set yet at this point, so we cannot easily * check if the flow is unidirectional here. */ int DecodeVXLAN(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, const uint8_t *pkt, uint32_t len) { DEBUG_VALIDATE_BUG_ON(pkt == NULL); /* Initial packet validation */ if (unlikely(!g_vxlan_enabled)) return TM_ECODE_FAILED; if (len < (VXLAN_HEADER_LEN + sizeof(EthernetHdr))) return TM_ECODE_FAILED; if (!PacketIncreaseCheckLayers(p)) { return TM_ECODE_FAILED; } const VXLANHeader *vxlanh = (const VXLANHeader *)pkt; if ((vxlanh->flags[0] & 0x08) == 0) return TM_ECODE_FAILED; switch (g_vxlan_reserved_check_mode) { case VXLAN_RES_CHECK_STRICT: if ((vxlanh->flags[0] & 0xF7) != 0 || /* All reserved bits are zero except I bit */ vxlanh->flags[1] != 0 || /* Second byte should be all zeros */ vxlanh->gdp != 0 || /* GDP field is reserved in standard VXLAN */ vxlanh->res != 0) { /* Last reserved byte should be zero */ return TM_ECODE_FAILED; } break; case VXLAN_RES_CHECK_PERMISSIVE: break; } #if DEBUG uint32_t vni = (vxlanh->vni[0] << 16) + (vxlanh->vni[1] << 8) + (vxlanh->vni[2]); SCLogDebug("VXLAN vni %u", vni); #endif /* Increment stats counter for VXLAN packets */ StatsCounterIncr(&tv->stats, dtv->counter_vxlan); EthernetHdr *ethh = (EthernetHdr *)(pkt + VXLAN_HEADER_LEN); bool eth_ok = false; /* Look at encapsulated Ethernet frame to get next protocol */ uint16_t eth_type = SCNtohs(ethh->eth_type); SCLogDebug("VXLAN ethertype 0x%04x", eth_type); switch (eth_type) { case ETHERNET_TYPE_ARP: SCLogDebug("VXLAN found ARP"); eth_ok = true; break; case ETHERNET_TYPE_IP: SCLogDebug("VXLAN found IPv4"); eth_ok = true; break; case ETHERNET_TYPE_IPV6: SCLogDebug("VXLAN found IPv6"); eth_ok = true; break; case ETHERNET_TYPE_VLAN: case ETHERNET_TYPE_8021AD: case ETHERNET_TYPE_8021QINQ: SCLogDebug("VXLAN found VLAN"); eth_ok = true; break; default: SCLogDebug("VXLAN found unsupported Ethertype - expected IPv4, IPv6, VLAN, or ARP"); ENGINE_SET_INVALID_EVENT(p, VXLAN_UNKNOWN_PAYLOAD_TYPE); } /* Set-up and process inner packet if it is a supported ethertype */ if (eth_ok) { Packet *tp = PacketTunnelPktSetup( tv, dtv, p, pkt + VXLAN_HEADER_LEN, len - VXLAN_HEADER_LEN, DECODE_TUNNEL_VXLAN); if (tp != NULL) { PKT_SET_SRC(tp, PKT_SRC_DECODER_VXLAN); PacketEnqueueNoLock(&tv->decode_pq, tp); } } return TM_ECODE_OK; } #ifdef UNITTESTS #include "conf-yaml-loader.h" /** * \test DecodeVXLANTest01 test a good vxlan header. * Contains a DNS request packet. */ static int DecodeVXLANtest01 (void) { uint8_t raw_vxlan[] = { 0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */ 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header */ 0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */ 0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11, 0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */ 0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */ }; Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); FAIL_IF(tv.decode_pq.top == NULL); Packet *tp = PacketDequeueNoLock(&tv.decode_pq); FAIL_IF_NOT(PacketIsUDP(tp)); FAIL_IF_NOT(tp->sp == 53); FlowShutdown(); PacketFree(p); PacketFreeOrRelease(tp); PASS; } /** * \test DecodeVXLANtest02 tests default port disabled by the config. */ static int DecodeVXLANtest02 (void) { uint8_t raw_vxlan[] = { 0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */ 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header */ 0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */ 0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11, 0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */ 0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */ }; Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfigPorts("1"); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); FAIL_IF(tv.decode_pq.top != NULL); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); /* reset */ FlowShutdown(); PacketFree(p); PASS; } /** * \test DecodeVXLANtest03 tests the non-zero res field on receiver side. * Contains a HTTP response packet. */ static int DecodeVXLANtest03(void) { uint8_t raw_vxlan[] = { 0xc0, 0x00, 0x12, 0xb5, 0x00, 0x57, 0x00, 0x00, /* UDP header */ 0xff, 0x01, 0xd2, 0x0a, 0x00, 0x00, 0x0b, 0x01, /* VXLAN header (res = 0x01) */ 0xfa, 0x16, 0x3e, 0xfe, 0x55, 0x1c, /* inner destination MAC */ 0xfa, 0x16, 0x3e, 0xfe, 0x57, 0xdc, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x39, 0xc2, 0xae, 0x40, 0x00, 0x40, 0x06, 0x7e, 0x61, 0xc0, 0xa8, 0x01, 0x86, 0xda, 0x5e, 0x5d, 0x22, /* IPv4 hdr */ 0x00, 0x50, 0xc8, 0x34, 0xaf, 0xbd, 0x02, 0x16, 0x56, 0xea, 0x3b, 0x41, 0x50, 0x18, 0x00, 0xee, 0xf9, 0xda, 0x00, 0x00, /* TCP probe src port 80 */ 0x48, 0x54, 0x54, 0x50, 0x2f, 0x31, 0x2e, 0x30, 0x20, 0x32, 0x30, 0x30, 0x20, 0x4f, 0x4b, 0xd, 0xa /* HTTP response (HTTP/1.0 200 OK\r\n) */ }; char config[] = "\ %YAML 1.1\n\ ---\n\ decoder:\n\ \n\ vxlan:\n\ enabled: true\n\ ports: \"4789\"\n\ reserved-bits-check: permissive\n\ "; SCConfCreateContextBackup(); SCConfInit(); SCConfYamlLoadString(config, strlen(config)); Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfig(); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); FAIL_IF(tv.decode_pq.top == NULL); Packet *tp = PacketDequeueNoLock(&tv.decode_pq); FAIL_IF_NOT(PacketIsTCP(tp)); FAIL_IF_NOT(tp->sp == 80); FlowShutdown(); PacketFree(p); PacketFreeOrRelease(tp); SCConfDeInit(); SCConfRestoreContextBackup(); PASS; } /** * \test DecodeVXLANtest04 tests strict mode with standard VXLAN header. */ static int DecodeVXLANtest04(void) { uint8_t raw_vxlan[] = { 0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */ 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x25, 0x00, /* VXLAN header (strict compliant) */ 0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */ 0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11, 0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */ 0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */ }; char config[] = "\ %YAML 1.1\n\ ---\n\ decoder:\n\ \n\ vxlan:\n\ enabled: true\n\ ports: \"4789\"\n\ reserved-bits-check: strict\n\ "; SCConfCreateContextBackup(); SCConfInit(); SCConfYamlLoadString(config, strlen(config)); Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfig(); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); FAIL_IF(tv.decode_pq.top == NULL); Packet *tp = PacketDequeueNoLock(&tv.decode_pq); FAIL_IF_NOT(PacketIsUDP(tp)); FAIL_IF_NOT(tp->sp == 53); FlowShutdown(); PacketFree(p); PacketFreeOrRelease(tp); SCConfDeInit(); SCConfRestoreContextBackup(); PASS; } /** * \test DecodeVXLANtest05 tests strict mode with GBP header (should fail). */ static int DecodeVXLANtest05(void) { uint8_t raw_vxlan[] = { 0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */ 0x88, 0x00, 0x12, 0x34, 0x00, 0x00, 0x25, 0x00, /* VXLAN-GBP header (G bit set, Group Policy ID) */ 0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */ 0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11, 0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */ 0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */ }; char config[] = "\ %YAML 1.1\n\ ---\n\ decoder:\n\ \n\ vxlan:\n\ enabled: true\n\ ports: \"4789\"\n\ reserved-bits-check: strict\n\ "; SCConfCreateContextBackup(); SCConfInit(); SCConfYamlLoadString(config, strlen(config)); Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfig(); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); /* Should fail to decode VXLAN in strict mode */ FAIL_IF(tv.decode_pq.top != NULL); FlowShutdown(); PacketFree(p); SCConfDeInit(); SCConfRestoreContextBackup(); PASS; } /** * \test DecodeVXLANtest06 tests permissive mode with GBP header (should pass). */ static int DecodeVXLANtest06(void) { uint8_t raw_vxlan[] = { 0x12, 0xb5, 0x12, 0xb5, 0x00, 0x3a, 0x87, 0x51, /* UDP header */ 0x88, 0x00, 0x12, 0x34, 0x00, 0x00, 0x25, 0x00, /* VXLAN-GBP header (G bit set, Group Policy ID) */ 0x10, 0x00, 0x00, 0x0c, 0x01, 0x00, /* inner destination MAC */ 0x00, 0x51, 0x52, 0xb3, 0x54, 0xe5, /* inner source MAC */ 0x08, 0x00, /* another IPv4 0x0800 */ 0x45, 0x00, 0x00, 0x1c, 0x00, 0x01, 0x00, 0x00, 0x40, 0x11, 0x44, 0x45, 0x0a, 0x60, 0x00, 0x0a, 0xb9, 0x1b, 0x73, 0x06, /* IPv4 hdr */ 0x00, 0x35, 0x30, 0x39, 0x00, 0x08, 0x98, 0xe4 /* UDP probe src port 53 */ }; char config[] = "\ %YAML 1.1\n\ ---\n\ decoder:\n\ \n\ vxlan:\n\ enabled: true\n\ ports: \"4789\"\n\ reserved-bits-check: permissive\n\ "; SCConfCreateContextBackup(); SCConfInit(); SCConfYamlLoadString(config, strlen(config)); Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfig(); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_vxlan, sizeof(raw_vxlan)); FAIL_IF_NOT(PacketIsUDP(p)); FAIL_IF(tv.decode_pq.top == NULL); Packet *tp = PacketDequeueNoLock(&tv.decode_pq); FAIL_IF_NOT(PacketIsUDP(tp)); FAIL_IF_NOT(tp->sp == 53); FlowShutdown(); PacketFree(p); PacketFreeOrRelease(tp); SCConfDeInit(); SCConfRestoreContextBackup(); PASS; } /** * \test DecodeVXLANtest07 tests that only destination port is checked for VXLAN identification. * Source port 4789, destination port 53 DNS query should NOT be VXLAN. */ static int DecodeVXLANtest07(void) { uint8_t raw_dns[] = { 0x12, 0xb5, 0x00, 0x35, 0x00, 0x24, 0xb9, 0xd7, /* UDP header (sp=4789, dp=53) */ 0x49, 0xa1, 0x01, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x03, 0x63, 0x6f, 0x6d, 0x00, 0x00, 0x1d, 0x00, 0x01 /* DNS query (google.com) */ }; Packet *p = PacketGetFromAlloc(); FAIL_IF_NULL(p); ThreadVars tv; DecodeThreadVars dtv; memset(&tv, 0, sizeof(ThreadVars)); memset(&dtv, 0, sizeof(DecodeThreadVars)); DecodeVXLANConfigPorts(VXLAN_DEFAULT_PORT_S); FlowInitConfig(FLOW_QUIET); DecodeUDP(&tv, &dtv, p, raw_dns, sizeof(raw_dns)); FAIL_IF_NOT(PacketIsUDP(p)); /* Should not be VXLAN packet, and not invalid packet */ FAIL_IF(DecodeVXLANEnabledForPort(p->dp)); FAIL_IF(tv.decode_pq.top != NULL); FAIL_IF(p->flags & PKT_IS_INVALID); FlowShutdown(); PacketFree(p); PASS; } #endif /* UNITTESTS */ void DecodeVXLANRegisterTests(void) { #ifdef UNITTESTS UtRegisterTest("DecodeVXLANtest01", DecodeVXLANtest01); UtRegisterTest("DecodeVXLANtest02", DecodeVXLANtest02); UtRegisterTest("DecodeVXLANtest03", DecodeVXLANtest03); UtRegisterTest("DecodeVXLANtest04", DecodeVXLANtest04); UtRegisterTest("DecodeVXLANtest05", DecodeVXLANtest05); UtRegisterTest("DecodeVXLANtest06", DecodeVXLANtest06); UtRegisterTest("DecodeVXLANtest07", DecodeVXLANtest07); #endif /* UNITTESTS */ }