flow_dissector: Add PPPoE dissectors
Allow to dissect PPPoE specific fields which are:
- session ID (16 bits)
- ppp protocol (16 bits)
- type (16 bits) - this is PPPoE ethertype, for now only
ETH_P_PPP_SES is supported, possible ETH_P_PPP_DISC
in the future
The goal is to make the following TC command possible:
# tc filter add dev ens6f0 ingress prio 1 protocol ppp_ses \
flower \
pppoe_sid 12 \
ppp_proto ip \
action drop
Note that only PPPoE Session is supported.
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 6aee04f..237d396 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -895,6 +895,11 @@ bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx,
return result == BPF_OK;
}
+static bool is_pppoe_ses_hdr_valid(struct pppoe_hdr hdr)
+{
+ return hdr.ver == 1 && hdr.type == 1 && hdr.code == 0;
+}
+
/**
* __skb_flow_dissect - extract the flow_keys struct and return it
* @net: associated network namespace, derived from @skb if NULL
@@ -1214,26 +1219,60 @@ bool __skb_flow_dissect(const struct net *net,
struct pppoe_hdr hdr;
__be16 proto;
} *hdr, _hdr;
+ u16 ppp_proto;
+
hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
if (!hdr) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
- nhoff += PPPOE_SES_HLEN;
- switch (hdr->proto) {
- case htons(PPP_IP):
- proto = htons(ETH_P_IP);
- fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
- break;
- case htons(PPP_IPV6):
- proto = htons(ETH_P_IPV6);
- fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
- break;
- default:
+ if (!is_pppoe_ses_hdr_valid(hdr->hdr)) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
+
+ /* least significant bit of the most significant octet
+ * indicates if protocol field was compressed
+ */
+ ppp_proto = ntohs(hdr->proto);
+ if (ppp_proto & 0x0100) {
+ ppp_proto = ppp_proto >> 8;
+ nhoff += PPPOE_SES_HLEN - 1;
+ } else {
+ nhoff += PPPOE_SES_HLEN;
+ }
+
+ if (ppp_proto == PPP_IP) {
+ proto = htons(ETH_P_IP);
+ fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
+ } else if (ppp_proto == PPP_IPV6) {
+ proto = htons(ETH_P_IPV6);
+ fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
+ } else if (ppp_proto == PPP_MPLS_UC) {
+ proto = htons(ETH_P_MPLS_UC);
+ fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
+ } else if (ppp_proto == PPP_MPLS_MC) {
+ proto = htons(ETH_P_MPLS_MC);
+ fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
+ } else if (ppp_proto_is_valid(ppp_proto)) {
+ fdret = FLOW_DISSECT_RET_OUT_GOOD;
+ } else {
+ fdret = FLOW_DISSECT_RET_OUT_BAD;
+ break;
+ }
+
+ if (dissector_uses_key(flow_dissector,
+ FLOW_DISSECTOR_KEY_PPPOE)) {
+ struct flow_dissector_key_pppoe *key_pppoe;
+
+ key_pppoe = skb_flow_dissector_target(flow_dissector,
+ FLOW_DISSECTOR_KEY_PPPOE,
+ target_container);
+ key_pppoe->session_id = hdr->hdr.sid;
+ key_pppoe->ppp_proto = htons(ppp_proto);
+ key_pppoe->type = htons(ETH_P_PPP_SES);
+ }
break;
}
case htons(ETH_P_TIPC): {
