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Date: Mon, 18 Jul 2022 14:18:10 +0200
From: Marcin Szycik <marcin.szycik@...ux.intel.com>
To: netdev@...r.kernel.org
Cc: anthony.l.nguyen@...el.com, davem@...emloft.net,
xiyou.wangcong@...il.com, jesse.brandeburg@...el.com,
gustavoars@...nel.org, baowen.zheng@...igine.com,
boris.sukholitko@...adcom.com, edumazet@...gle.com,
kuba@...nel.org, jhs@...atatu.com, jiri@...nulli.us,
kurt@...utronix.de, pablo@...filter.org, pabeni@...hat.com,
paulb@...dia.com, simon.horman@...igine.com,
komachi.yoshiki@...il.com, zhangkaiheb@....com,
intel-wired-lan@...ts.osuosl.org,
michal.swiatkowski@...ux.intel.com, wojciech.drewek@...el.com,
alexandr.lobakin@...el.com, gnault@...hat.com,
mostrows@...akeasy.net, paulus@...ba.org
Subject: [RFC PATCH net-next v6 1/4] flow_dissector: Add PPPoE dissectors
From: Wojciech Drewek <wojciech.drewek@...el.com>
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@...el.com>
---
v6:
* make check for ppp proto more generic
* fix remaining byte order issues
v5: fix endianness when processing compressed protocols
v4:
* pppoe header validation
* added MPLS dissection
* added support for compressed ppp protocol field
* flow_dissector_key_pppoe::session_id stored in __be16
* new field: flow_dissector_key_pppoe::type
v3: revert byte order changes in is_ppp_proto_supported from
previous version
v2: ntohs instead of htons in is_ppp_proto_supported
include/linux/ppp_defs.h | 14 ++++++++++
include/net/flow_dissector.h | 13 +++++++++
net/core/flow_dissector.c | 53 +++++++++++++++++++++++++++++++-----
3 files changed, 73 insertions(+), 7 deletions(-)
diff --git a/include/linux/ppp_defs.h b/include/linux/ppp_defs.h
index 9d2b388fae1a..b7e57fdbd413 100644
--- a/include/linux/ppp_defs.h
+++ b/include/linux/ppp_defs.h
@@ -11,4 +11,18 @@
#include <uapi/linux/ppp_defs.h>
#define PPP_FCS(fcs, c) crc_ccitt_byte(fcs, c)
+
+/**
+ * ppp_proto_is_valid - checks if PPP protocol is valid
+ * @proto: PPP protocol
+ *
+ * Assumes proto is not compressed.
+ * Protocol is valid if the value is odd and the least significant bit of the
+ * most significant octet is 0 (see RFC 1661, section 2).
+ */
+static inline bool ppp_proto_is_valid(u16 proto)
+{
+ return !!((proto & 0x0101) == 0x0001);
+}
+
#endif /* _PPP_DEFS_H_ */
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 0f9544a9bb9e..6c74812d64b2 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -277,6 +277,18 @@ 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
+ * @type: pppoe eth type
+ */
+struct flow_dissector_key_pppoe {
+ __be16 session_id;
+ __be16 ppp_proto;
+ __be16 type;
+};
+
enum flow_dissector_key_id {
FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
@@ -307,6 +319,7 @@ 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..237d396b6e41 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):
+ 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;
- break;
- case htons(PPP_IPV6):
+ } else if (ppp_proto == PPP_IPV6) {
proto = htons(ETH_P_IPV6);
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
- break;
- default:
+ } 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): {
--
2.35.1
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