No, I was referring to anonymous structures, which is a feature of C11.

Please see the link I sent.


On 08/08/2016 03:13 AM, Feng Gao wrote:
Hi Philip,

Do you mean like the following?

struct gre_full_hdr {
         struct {
                 __be16 flags;
                 __be16 protocol;
         } fixed_header;
         __be16 csum;
         __be16 reserved1;
         __be32 key;
         __be32 seq;
} __packed;

But we need struct gre_base_hdr to get the fixed header of GRE in
function __skb_flow_dissect like the following codes.
struct gre_base_hdr *hdr, _hdr;
hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);

BTW, the original codes define one local stuct gre_hdr. Now I use the
unified struct gre_base_hdr instead of it.

Best Regards
Feng


On Mon, Aug 8, 2016 at 11:27 AM, Philp Prindeville
<phil...@redfish-solutions.com> wrote:
Feng,

An anonymous structure is defined here:
https://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html

i.e.:

struct gre_full_hdr {
     struct gre_base_hdr;
     ...

so yes, I'm talking about making fixed_header be anonymous instead.

-Philip



On 08/07/2016 08:50 PM, Feng Gao wrote:
Hi Philp,

Forgive my poor English, I am not clear about the comment #1.
"Can you make gre_base_hdr be anonymous?".

+struct gre_full_hdr {
+   struct gre_base_hdr fixed_header;

Do you mean make the member "fixed_header" as anonymous or not?

Best Regards
Feng


On Mon, Aug 8, 2016 at 5:03 AM, Philp Prindeville
<phil...@redfish-solutions.com> wrote:
Inline...



On 08/04/2016 01:06 AM, f...@48lvckh6395k16k5.yundunddos.com wrote:
From: Gao Feng <f...@ikuai8.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 <f...@ikuai8.com>
---
    v4: 1) Define struct gre_full_hdr, and use sizeof its member
directly;
        2) Move version and routing check ahead;
        3) Only PPTP in GRE check the ack flag;
    v3: 1) Move struct pptp_gre_header defination into new file pptp.h
        2) Use sizeof GRE and PPTP type instead of literal value;
        3) Remove strict flag check for PPTP to robust;
        4) Consolidate the codes again;
    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: Intial Patch

    drivers/net/ppp/pptp.c         |  36 +------------
    include/net/gre.h              |  10 +++-
    include/net/pptp.h             |  40 +++++++++++++++
    include/uapi/linux/if_tunnel.h |   7 ++-
    net/core/flow_dissector.c      | 113
++++++++++++++++++++++++++++-------------
    5 files changed, 135 insertions(+), 71 deletions(-)
    create mode 100644 include/net/pptp.h

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index ae0905e..3e68dbc 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -37,6 +37,7 @@
    #include <net/icmp.h>
    #include <net/route.h>
    #include <net/gre.h>
+#include <net/pptp.h>
      #include <linux/uaccess.h>
    @@ -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;
diff --git a/include/net/gre.h b/include/net/gre.h
index 7a54a31..c469dcc 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -7,9 +7,17 @@
    struct gre_base_hdr {
          __be16 flags;
          __be16 protocol;
-};
+} __packed;
    #define GRE_HEADER_SECTION 4
    +struct gre_full_hdr {
+       struct gre_base_hdr fixed_header;

Can you make gre_base_hdr be anonymous?



+       __be16 csum;
+       __be16 reserved1;
+       __be32 key;
+       __be32 seq;
+} __packed;
+
    #define GREPROTO_CISCO                0
    #define GREPROTO_PPTP         1
    #define GREPROTO_MAX          2
diff --git a/include/net/pptp.h b/include/net/pptp.h
new file mode 100644
index 0000000..301d3e2
--- /dev/null
+++ b/include/net/pptp.h
@@ -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
diff --git a/include/uapi/linux/if_tunnel.h
b/include/uapi/linux/if_tunnel.h
index 1046f55..7d889db 100644
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -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)
+
+
    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..1186712 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -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>
@@ -338,32 +340,42 @@ mpls:
    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;
    @@ -372,32 +384,65 @@ ip_proto_again:
                                  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 &
htonl(0xffff);

Would be good to have a #define'd constant for the keyid mask...
Otherwise,
looks good.

-Philip


                          }
-                       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;


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