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Date: Wed, 3 Aug 2016 08:28:24 +0800
From: Feng Gao <gfree.wind@...il.com>
To: Tom Herbert <tom@...bertland.com>
Cc: Gao Feng <fgao@...ai8.com>,
"David S. Miller" <davem@...emloft.net>,
Philp Prindeville <philipp@...fish-solutions.com>,
Stephen Hemminger <stephen@...workplumber.org>,
Pravin B Shelar <pshelar@...ira.com>,
Alex Duyck <aduyck@...antis.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/1] rps: Inspect PPTP encapsulated by GRE to get flow hash
Hi Tom.
I quote some description in RFC 2637.
/*********************************************************************/
C
(Bit 0) Checksum Present. Set to zero (0).
R
(Bit 1) Routing Present. Set to zero (0).
K
(Bit 2) Key Present. Set to one (1).
S
(Bit 3) Sequence Number Present. Set to one (1) if a payload
(data) packet is present. Set to zero (0) if payload is not
present (GRE packet is an Acknowledgment only).
s
(Bit 4) Strict source route present. Set to zero (0).
Recur
(Bits 5-7) Recursion control. Set to zero (0).
A
(Bit 8) Acknowledgment sequence number present. Set to one (1) if
packet contains Acknowledgment Number to be used for acknowledging
previously transmitted data.
Flags
(Bits 9-12) Must be set to zero (0).
Ver
(Bits 13-15) Must contain 1 (enhanced GRE).
Protocol Type
Set to hex 880B [8].
Key
Use of the Key field is up to the implementation. PPTP uses it as
follows:
Payload Length
(High 2 octets of Key) Size of the payload, not including
the GRE header
Call ID
(Low 2 octets) Contains the Peer's Call ID for the session
to which this packet belongs.
/*********************************************************************/
Just a reminder, the version description is "contain 1", not "set 1".
Best Regards
Feng
On Wed, Aug 3, 2016 at 4:35 AM, Tom Herbert <tom@...bertland.com> wrote:
> On Thu, Jul 28, 2016 at 12:14 AM, <fgao@...ai8.com> wrote:
>> From: Gao Feng <fgao@...ai8.com>
>>
>> The PPTP is encapsulated by GRE header with that GRE_VERSION bits
>> must contain one. But current GRE RPS needs the GRE_VERSION must be
>> zero. So RPS does not work for PPTP traffic.
>>
>> In my test environment, there are four MIPS cores, and all traffic
>> are passed through by PPTP. As a result, only one core is 100% busy
>> while other three cores are very idle. After this patch, the usage
>> of four cores are balanced well.
>>
>> Signed-off-by: Gao Feng <fgao@...ai8.com>
>> ---
>> v2: Update according to Tom and Philp's advice.
>> 1) Consolidate the codes with GRE version 0 path;
>> 2) Use PPP_PROTOCOL to get ppp protol;
>> 3) Set the FLOW_DIS_ENCAPSULATION flag;
>> v1: Initial patch
>>
>> include/uapi/linux/if_tunnel.h | 5 +-
>> net/core/flow_dissector.c | 146 ++++++++++++++++++++++++++---------------
>> 2 files changed, 97 insertions(+), 54 deletions(-)
>>
>> diff --git a/include/uapi/linux/if_tunnel.h b/include/uapi/linux/if_tunnel.h
>> index 1046f55..dda4e4b 100644
>> --- a/include/uapi/linux/if_tunnel.h
>> +++ b/include/uapi/linux/if_tunnel.h
>> @@ -24,9 +24,12 @@
>> #define GRE_SEQ __cpu_to_be16(0x1000)
>> #define GRE_STRICT __cpu_to_be16(0x0800)
>> #define GRE_REC __cpu_to_be16(0x0700)
>> -#define GRE_FLAGS __cpu_to_be16(0x00F8)
>> +#define GRE_ACK __cpu_to_be16(0x0080)
>> +#define GRE_FLAGS __cpu_to_be16(0x0078)
>> #define GRE_VERSION __cpu_to_be16(0x0007)
>>
>> +#define GRE_PROTO_PPP __cpu_to_be16(0x880b)
>> +
>> struct ip_tunnel_parm {
>> char name[IFNAMSIZ];
>> int link;
>> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
>> index 61ad43f..33e957b 100644
>> --- a/net/core/flow_dissector.c
>> +++ b/net/core/flow_dissector.c
>> @@ -346,63 +346,103 @@ ip_proto_again:
>> hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
>> if (!hdr)
>> goto out_bad;
>> - /*
>> - * Only look inside GRE if version zero and no
>> - * routing
>> - */
>> - if (hdr->flags & (GRE_VERSION | GRE_ROUTING))
>> - break;
>> -
>> - proto = hdr->proto;
>> - nhoff += 4;
>> - if (hdr->flags & GRE_CSUM)
>> - nhoff += 4;
>> - if (hdr->flags & GRE_KEY) {
>> - const __be32 *keyid;
>> - __be32 _keyid;
>> -
>> - keyid = __skb_header_pointer(skb, nhoff, sizeof(_keyid),
>> - data, hlen, &_keyid);
>>
>> - if (!keyid)
>> - goto out_bad;
>> + /* Only look inside GRE without routing */
>> + if (!(hdr->flags & GRE_ROUTING)) {
>> + proto = hdr->proto;
>> +
>> + if (hdr->flags & GRE_VERSION) {
>
> This matches any non-zero GRE version (1-7). Is that really what you want?
>
>> + /* It should be the PPTP in GRE */
>> + u8 _ppp_hdr[PPP_HDRLEN];
>> + u8 *ppp_hdr;
>> + int offset = 0;
>> +
>> + /* Check the flags according to RFC 2637*/
>> + if (!(proto == GRE_PROTO_PPP && (hdr->flags & GRE_KEY) &&
>> + !(hdr->flags & (GRE_CSUM | GRE_STRICT | GRE_REC | GRE_FLAGS)))) {
>> + break;
>> + }
>> +
> I might be missing something, but I only see two material differences
> between v0 and v1 of GRE. First is that keyid in v1 has specific use
> that is not appropriate to use as entropy. Second is how the payload
> is parsed. All the flag processing is common so it stills seems like
> this should be consolidated.
>
>> + /* Skip GRE header */
>> + offset += 4;
>> + /* Skip payload length and call id */
>> + offset += 4;
>> +
>> + if (hdr->flags & GRE_SEQ)
>> + offset += 4;
>> +
>> + if (hdr->flags & GRE_ACK)
>> + offset += 4;
>> +
>> + ppp_hdr = skb_header_pointer(skb, nhoff + offset, sizeof(_ppp_hdr), _ppp_hdr);
>> + if (!ppp_hdr)
>> + goto out_bad;
>> + proto = PPP_PROTOCOL(ppp_hdr);
>> + if (proto == PPP_IP) {
>> + nhoff += (PPP_HDRLEN + offset);
>> + proto = htons(ETH_P_IP);
>> + key_control->flags |= FLOW_DIS_ENCAPSULATION;
>> + goto again;
>> + } else if (proto == PPP_IPV6) {
>> + nhoff += (PPP_HDRLEN + offset);
>> + proto = htons(ETH_P_IPV6);
>> + key_control->flags |= FLOW_DIS_ENCAPSULATION;
>> + goto again;
>> + }
>> + } else {
>> + /* Original GRE */
>> + nhoff += 4;
>> + if (hdr->flags & GRE_CSUM)
>> + nhoff += 4;
>> + if (hdr->flags & GRE_KEY) {
>> + const __be32 *keyid;
>> + __be32 _keyid;
>> +
>> + keyid = __skb_header_pointer(skb, nhoff, sizeof(_keyid),
>> + data, hlen, &_keyid);
>> +
>> + if (!keyid)
>> + goto out_bad;
>> +
>> + if (dissector_uses_key(flow_dissector,
>> + FLOW_DISSECTOR_KEY_GRE_KEYID)) {
>> + key_keyid = skb_flow_dissector_target(flow_dissector,
>> + FLOW_DISSECTOR_KEY_GRE_KEYID,
>> + target_container);
>> + key_keyid->keyid = *keyid;
>> + }
>> + nhoff += 4;
>> + }
>> + if (hdr->flags & GRE_SEQ)
>> + nhoff += 4;
>> + if (proto == htons(ETH_P_TEB)) {
>> + const struct ethhdr *eth;
>> + struct ethhdr _eth;
>> +
>> + eth = __skb_header_pointer(skb, nhoff,
>> + sizeof(_eth),
>> + data, hlen, &_eth);
>> + if (!eth)
>> + goto out_bad;
>> + proto = eth->h_proto;
>> + nhoff += sizeof(*eth);
>> +
>> + /* Cap headers that we access via pointers at the
>> + * end of the Ethernet header as our maximum alignment
>> + * at that point is only 2 bytes.
>> + */
>> + if (NET_IP_ALIGN)
>> + hlen = nhoff;
>> + }
>> +
>> + key_control->flags |= FLOW_DIS_ENCAPSULATION;
>> + if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
>> + goto out_good;
>>
>> - if (dissector_uses_key(flow_dissector,
>> - FLOW_DISSECTOR_KEY_GRE_KEYID)) {
>> - key_keyid = skb_flow_dissector_target(flow_dissector,
>> - FLOW_DISSECTOR_KEY_GRE_KEYID,
>> - target_container);
>> - key_keyid->keyid = *keyid;
>> + goto again;
>> }
>> - nhoff += 4;
>> - }
>> - if (hdr->flags & GRE_SEQ)
>> - nhoff += 4;
>> - if (proto == htons(ETH_P_TEB)) {
>> - const struct ethhdr *eth;
>> - struct ethhdr _eth;
>> -
>> - eth = __skb_header_pointer(skb, nhoff,
>> - sizeof(_eth),
>> - data, hlen, &_eth);
>> - if (!eth)
>> - goto out_bad;
>> - proto = eth->h_proto;
>> - nhoff += sizeof(*eth);
>> -
>> - /* Cap headers that we access via pointers at the
>> - * end of the Ethernet header as our maximum alignment
>> - * at that point is only 2 bytes.
>> - */
>> - if (NET_IP_ALIGN)
>> - hlen = nhoff;
>> }
>> -
>> - key_control->flags |= FLOW_DIS_ENCAPSULATION;
>> - if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
>> - goto out_good;
>> -
>> - goto again;
>> + break;
>> }
>> case NEXTHDR_HOP:
>> case NEXTHDR_ROUTING:
>> --
>> 1.9.1
>>
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