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rps: Inspect PPTP encapsulated by GRE to get flow hash
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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@ikuai8.com>
Reviewed-by: Philip Prindeville <philipp@redfish-solutions.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@gfreewind @davem330
gfreewind authored and davem330 committed Aug 11, 2016
1 parent 084c953 commit ab10dcc
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Showing 5 changed files with 135 additions and 71 deletions.
36 changes: 1 addition & 35 deletions drivers/net/ppp/pptp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@
#include <net/icmp.h>
#include <net/route.h>
#include <net/gre.h>
#include <net/pptp.h>

#include <linux/uaccess.h>

Expand All @@ -53,41 +54,6 @@ static struct proto pptp_sk_proto __read_mostly;
static const struct ppp_channel_ops pptp_chan_ops;
static const struct proto_ops pptp_ops;

#define PPP_LCP_ECHOREQ 0x09
#define PPP_LCP_ECHOREP 0x0A
#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)

#define MISSING_WINDOW 20
#define WRAPPED(curseq, lastseq)\
((((curseq) & 0xffffff00) == 0) &&\
(((lastseq) & 0xffffff00) == 0xffffff00))

#define PPTP_GRE_PROTO 0x880B
#define PPTP_GRE_VER 0x1

#define PPTP_GRE_FLAG_C 0x80
#define PPTP_GRE_FLAG_R 0x40
#define PPTP_GRE_FLAG_K 0x20
#define PPTP_GRE_FLAG_S 0x10
#define PPTP_GRE_FLAG_A 0x80

#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)

#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
struct pptp_gre_header {
u8 flags;
u8 ver;
__be16 protocol;
__be16 payload_len;
__be16 call_id;
__be32 seq;
__be32 ack;
} __packed;

static struct pppox_sock *lookup_chan(u16 call_id, __be32 s_addr)
{
struct pppox_sock *sock;
Expand Down
10 changes: 9 additions & 1 deletion include/net/gre.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,15 @@
struct gre_base_hdr {
__be16 flags;
__be16 protocol;
};
} __packed;

struct gre_full_hdr {
struct gre_base_hdr fixed_header;
__be16 csum;
__be16 reserved1;
__be32 key;
__be32 seq;
} __packed;
#define GRE_HEADER_SECTION 4

#define GREPROTO_CISCO 0
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40 changes: 40 additions & 0 deletions include/net/pptp.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
#ifndef _NET_PPTP_H
#define _NET_PPTP_H

#define PPP_LCP_ECHOREQ 0x09
#define PPP_LCP_ECHOREP 0x0A
#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)

#define MISSING_WINDOW 20
#define WRAPPED(curseq, lastseq)\
((((curseq) & 0xffffff00) == 0) &&\
(((lastseq) & 0xffffff00) == 0xffffff00))

#define PPTP_GRE_PROTO 0x880B
#define PPTP_GRE_VER 0x1

#define PPTP_GRE_FLAG_C 0x80
#define PPTP_GRE_FLAG_R 0x40
#define PPTP_GRE_FLAG_K 0x20
#define PPTP_GRE_FLAG_S 0x10
#define PPTP_GRE_FLAG_A 0x80

#define PPTP_GRE_IS_C(f) ((f)&PPTP_GRE_FLAG_C)
#define PPTP_GRE_IS_R(f) ((f)&PPTP_GRE_FLAG_R)
#define PPTP_GRE_IS_K(f) ((f)&PPTP_GRE_FLAG_K)
#define PPTP_GRE_IS_S(f) ((f)&PPTP_GRE_FLAG_S)
#define PPTP_GRE_IS_A(f) ((f)&PPTP_GRE_FLAG_A)

#define PPTP_HEADER_OVERHEAD (2+sizeof(struct pptp_gre_header))
struct pptp_gre_header {
u8 flags;
u8 ver;
__be16 protocol;
__be16 payload_len;
__be16 call_id;
__be32 seq;
__be32 ack;
} __packed;


#endif
7 changes: 6 additions & 1 deletion include/uapi/linux/if_tunnel.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,14 @@
#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_VERSION_1 __cpu_to_be16(0x0001)
#define GRE_PROTO_PPP __cpu_to_be16(0x880b)
#define GRE_PPTP_KEY_MASK __cpu_to_be32(0xffff)

struct ip_tunnel_parm {
char name[IFNAMSIZ];
int link;
Expand Down
113 changes: 79 additions & 34 deletions net/core/flow_dissector.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@
#include <linux/if_vlan.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/gre.h>
#include <net/pptp.h>
#include <linux/igmp.h>
#include <linux/icmp.h>
#include <linux/sctp.h>
Expand Down Expand Up @@ -338,32 +340,42 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
ip_proto_again:
switch (ip_proto) {
case IPPROTO_GRE: {
struct gre_hdr {
__be16 flags;
__be16 proto;
} *hdr, _hdr;
struct gre_base_hdr *hdr, _hdr;
u16 gre_ver;
int offset = 0;

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))

/* Only look inside GRE without routing */
if (hdr->flags & GRE_ROUTING)
break;

proto = hdr->proto;
nhoff += 4;
/* Only look inside GRE for version 0 and 1 */
gre_ver = ntohs(hdr->flags & GRE_VERSION);
if (gre_ver > 1)
break;

proto = hdr->protocol;
if (gre_ver) {
/* Version1 must be PPTP, and check the flags */
if (!(proto == GRE_PROTO_PPP && (hdr->flags & GRE_KEY)))
break;
}

offset += sizeof(struct gre_base_hdr);

if (hdr->flags & GRE_CSUM)
nhoff += 4;
offset += sizeof(((struct gre_full_hdr *)0)->csum) +
sizeof(((struct gre_full_hdr *)0)->reserved1);

if (hdr->flags & GRE_KEY) {
const __be32 *keyid;
__be32 _keyid;

keyid = __skb_header_pointer(skb, nhoff, sizeof(_keyid),
keyid = __skb_header_pointer(skb, nhoff + offset, sizeof(_keyid),
data, hlen, &_keyid);

if (!keyid)
goto out_bad;

Expand All @@ -372,32 +384,65 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
key_keyid = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_GRE_KEYID,
target_container);
key_keyid->keyid = *keyid;
if (gre_ver == 0)
key_keyid->keyid = *keyid;
else
key_keyid->keyid = *keyid & GRE_PPTP_KEY_MASK;
}
nhoff += 4;
offset += sizeof(((struct gre_full_hdr *)0)->key);
}

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)
offset += sizeof(((struct pptp_gre_header *)0)->seq);

if (gre_ver == 0) {
if (proto == htons(ETH_P_TEB)) {
const struct ethhdr *eth;
struct ethhdr _eth;

eth = __skb_header_pointer(skb, nhoff + offset,
sizeof(_eth),
data, hlen, &_eth);
if (!eth)
goto out_bad;
proto = eth->h_proto;
offset += 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 + offset);
}
} else { /* version 1, must be PPTP */
u8 _ppp_hdr[PPP_HDRLEN];
u8 *ppp_hdr;

if (hdr->flags & GRE_ACK)
offset += sizeof(((struct pptp_gre_header *)0)->ack);

ppp_hdr = skb_header_pointer(skb, nhoff + offset,
sizeof(_ppp_hdr), _ppp_hdr);
if (!ppp_hdr)
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;

switch (PPP_PROTOCOL(ppp_hdr)) {
case PPP_IP:
proto = htons(ETH_P_IP);
break;
case PPP_IPV6:
proto = htons(ETH_P_IPV6);
break;
default:
/* Could probably catch some more like MPLS */
break;
}

offset += PPP_HDRLEN;
}

nhoff += offset;
key_control->flags |= FLOW_DIS_ENCAPSULATION;
if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
goto out_good;
Expand Down

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