1 files changed, 115 insertions, 0 deletions
diff --git a/src/decode-erspan.c b/src/decode-erspan.c
new file mode 100644
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+/* Copyright (C) 2020-2021 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.
+ */
+
+/**
+ * \ingroup decode
+ *
+ * @{
+ */
+
+
+/**
+ * \file
+ *
+ * \author Victor Julien <victor@inliniac.net>
+ *
+ * Decodes ERSPAN Types I and II
+ */
+
+#include "suricata-common.h"
+#include "suricata.h"
+#include "decode.h"
+#include "decode-events.h"
+#include "decode-erspan.h"
+
+#include "util-validate.h"
+#include "util-unittest.h"
+#include "util-debug.h"
+
+/**
+ * \brief Functions to decode ERSPAN Type I and II packets
+ */
+
+/*
+ * \brief ERSPAN Type I was configurable in 5.0.x but is no longer configurable.
+ *
+ * Issue a warning if a configuration setting is found.
+ */
+void DecodeERSPANConfig(void)
+{
+    int enabled = 0;
+    if (ConfGetBool("decoder.erspan.typeI.enabled", &enabled) == 1) {
+        SCLogWarning("ERSPAN Type I is no longer configurable and it is always"
+                     " enabled; ignoring configuration setting.");
+    }
+}
+
+/**
+ * \brief ERSPAN Type I
+ */
+int DecodeERSPANTypeI(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p,
+                      const uint8_t *pkt, uint32_t len)
+{
+    StatsIncr(tv, dtv->counter_erspan);
+
+    return DecodeEthernet(tv, dtv, p, pkt, len);
+}
+
+/**
+ * \brief ERSPAN Type II
+ */
+int DecodeERSPAN(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, const uint8_t *pkt, uint32_t len)
+{
+    DEBUG_VALIDATE_BUG_ON(pkt == NULL);
+
+    StatsIncr(tv, dtv->counter_erspan);
+
+    if (len < sizeof(ErspanHdr)) {
+        ENGINE_SET_EVENT(p,ERSPAN_HEADER_TOO_SMALL);
+        return TM_ECODE_FAILED;
+    }
+    if (!PacketIncreaseCheckLayers(p)) {
+        return TM_ECODE_FAILED;
+    }
+
+    const ErspanHdr *ehdr = (const ErspanHdr *)pkt;
+    uint16_t version = SCNtohs(ehdr->ver_vlan) >> 12;
+    uint16_t vlan_id = SCNtohs(ehdr->ver_vlan) & 0x0fff;
+
+    SCLogDebug("ERSPAN: version %u vlan %u", version, vlan_id);
+
+    /* only v1 is tested at this time */
+    if (version != 1) {
+        ENGINE_SET_EVENT(p,ERSPAN_UNSUPPORTED_VERSION);
+        return TM_ECODE_FAILED;
+    }
+
+    if (vlan_id > 0) {
+        if (p->vlan_idx > VLAN_MAX_LAYER_IDX) {
+            ENGINE_SET_EVENT(p,ERSPAN_TOO_MANY_VLAN_LAYERS);
+            return TM_ECODE_FAILED;
+        }
+        p->vlan_id[p->vlan_idx] = vlan_id;
+        p->vlan_idx++;
+    }
+
+    return DecodeEthernet(tv, dtv, p, pkt + sizeof(ErspanHdr), len - sizeof(ErspanHdr));
+}
+
+/**
+ * @}
+ */