[Cake] Fwd: [RFC PATCH net-next v3 1/4] flow_dissector: Add PPPoE dissectors

[Dave Taht]

ppp makes my head hurt. so does mpls. when do we need to dissect it?

---------- Forwarded message ---------
From: Marcin Szycik <marcin.szycik at linux.intel.com>
Date: Wed, Jun 29, 2022 at 8:01 AM
Subject: [RFC PATCH net-next v3 1/4] flow_dissector: Add PPPoE dissectors
To: <netdev at vger.kernel.org>
Cc: <anthony.l.nguyen at intel.com>, <davem at davemloft.net>,
<xiyou.wangcong at gmail.com>, <jesse.brandeburg at intel.com>,
<gustavoars at kernel.org>, <baowen.zheng at corigine.com>,
<boris.sukholitko at broadcom.com>, <edumazet at google.com>,
<kuba at kernel.org>, <jhs at mojatatu.com>, <jiri at resnulli.us>,
<kurt at linutronix.de>, <pablo at netfilter.org>, <pabeni at redhat.com>,
<paulb at nvidia.com>, <simon.horman at corigine.com>,
<komachi.yoshiki at gmail.com>, <zhangkaiheb at 126.com>,
<intel-wired-lan at lists.osuosl.org>,
<michal.swiatkowski at linux.intel.com>, <wojciech.drewek at intel.com>,
<alexandr.lobakin at intel.com>, <gnault at redhat.com>,
<mostrows at earthlink.net>, <paulus at samba.org>


From: Wojciech Drewek <wojciech.drewek at intel.com>

Allow to dissect PPPoE specific fields which are:
- session ID (16 bits)
- ppp protocol (16 bits)

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 at intel.com>
---
v3: revert byte order changes in is_ppp_proto_supported from previous
    version, add kernel-doc for is_ppp_proto_supported
v2: use ntohs instead of htons in is_ppp_proto_supported

 include/net/flow_dissector.h | 11 ++++++++
 net/core/flow_dissector.c    | 55 ++++++++++++++++++++++++++++++++----
 2 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index a4c6057c7097..8ff40c7c3f1c 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -261,6 +261,16 @@ struct flow_dissector_key_num_of_vlans {
        u8 num_of_vlans;
 };

+/**
+ * struct flow_dissector_key_pppoe:
+ * @session_id: pppoe session id
+ * @ppp_proto: ppp protocol
+ */
+struct flow_dissector_key_pppoe {
+       u16 session_id;
+       __be16 ppp_proto;
+};
+
 enum flow_dissector_key_id {
        FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
        FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
@@ -291,6 +301,7 @@ enum flow_dissector_key_id {
        FLOW_DISSECTOR_KEY_CT, /* struct flow_dissector_key_ct */
        FLOW_DISSECTOR_KEY_HASH, /* struct flow_dissector_key_hash */
        FLOW_DISSECTOR_KEY_NUM_OF_VLANS, /* struct
flow_dissector_key_num_of_vlans */
+       FLOW_DISSECTOR_KEY_PPPOE,  /* struct flow_dissector_key_pppoe */

        FLOW_DISSECTOR_KEY_MAX,
 };
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 6aee04f75e3e..42393af477a2 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -895,6 +895,39 @@ bool bpf_flow_dissect(struct bpf_prog *prog,
struct bpf_flow_dissector *ctx,
        return result == BPF_OK;
 }

+/**
+ * is_ppp_proto_supported - checks if inner PPP protocol should be dissected
+ * @proto: protocol type (PPP proto field)
+ */
+static bool is_ppp_proto_supported(__be16 proto)
+{
+       switch (proto) {
+       case htons(PPP_AT):
+       case htons(PPP_IPX):
+       case htons(PPP_VJC_COMP):
+       case htons(PPP_VJC_UNCOMP):
+       case htons(PPP_MP):
+       case htons(PPP_COMPFRAG):
+       case htons(PPP_COMP):
+       case htons(PPP_MPLS_UC):
+       case htons(PPP_MPLS_MC):
+       case htons(PPP_IPCP):
+       case htons(PPP_ATCP):
+       case htons(PPP_IPXCP):
+       case htons(PPP_IPV6CP):
+       case htons(PPP_CCPFRAG):
+       case htons(PPP_MPLSCP):
+       case htons(PPP_LCP):
+       case htons(PPP_PAP):
+       case htons(PPP_LQR):
+       case htons(PPP_CHAP):
+       case htons(PPP_CBCP):
+               return true;
+       default:
+               return false;
+       }
+}
+
 /**
  * __skb_flow_dissect - extract the flow_keys struct and return it
  * @net: associated network namespace, derived from @skb if NULL
@@ -1221,19 +1254,29 @@ bool __skb_flow_dissect(const struct net *net,
                }

                nhoff += PPPOE_SES_HLEN;
-               switch (hdr->proto) {
-               case htons(PPP_IP):
+               if (hdr->proto == htons(PPP_IP)) {
                        proto = htons(ETH_P_IP);
                        fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
-                       break;
-               case htons(PPP_IPV6):
+               } else if (hdr->proto == htons(PPP_IPV6)) {
                        proto = htons(ETH_P_IPV6);
                        fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
-                       break;
-               default:
+               } else if (is_ppp_proto_supported(hdr->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 = ntohs(hdr->hdr.sid);
+                       key_pppoe->ppp_proto = hdr->proto;
+               }
                break;
        }
        case htons(ETH_P_TIPC): {
--
2.35.1



-- 
FQ World Domination pending: https://blog.cerowrt.org/post/state_of_fq_codel/
Dave Täht CEO, TekLibre, LLC