PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)

PPP: introduce "pptp" module which implements point-to-point tunneling protocol using pppox framework
NET: introduce the "gre" module for demultiplexing GRE packets on version criteria
     (required to pptp and ip_gre may coexists)
NET: ip_gre: update to use the "gre" module

This patch introduces then pptp support to the linux kernel which
dramatically speeds up pptp vpn connections and decreases cpu usage in
comparison of existing user-space implementation
(poptop/pptpclient). There is accel-pptp project
(https://sourceforge.net/projects/accel-pptp/) to utilize this module,
it contains plugin for pppd to use pptp in client-mode and modified
pptpd (poptop) to build high-performance pptp NAS.

There was many changes from initial submitted patch, most important are:
1. using rcu instead of read-write locks
2. using static bitmap instead of dynamically allocated
3. using vmalloc for memory allocation instead of BITS_PER_LONG + __get_free_pages
4. fixed many coding style issues
Thanks to Eric Dumazet.

Signed-off-by: Dmitry Kozlov <xeb@mail.ru>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 53 insertions, 17 deletions

diff --git a/include/linux/if_pppox.h b/include/linux/if_pppox.h
index 1925e0c3f162..1525b2156b2a 100644
--- a/include/linux/if_pppox.h
+++ b/include/linux/if_pppox.h
@@ -40,25 +40,35 @@
  * PPPoE addressing definition 
  */ 
 typedef __be16 sid_t;
-struct pppoe_addr{ 
-       sid_t           sid;                    /* Session identifier */ 
-       unsigned char   remote[ETH_ALEN];       /* Remote address */ 
-       char            dev[IFNAMSIZ];          /* Local device to use */ 
+struct pppoe_addr {
+        sid_t         sid;                    /* Session identifier */
+        unsigned char remote[ETH_ALEN];       /* Remote address */
+        char          dev[IFNAMSIZ];          /* Local device to use */
 }; 
  
 /************************************************************************ 
- * Protocols supported by AF_PPPOX 
- */ 
+ * PPTP addressing definition
+ */
+struct pptp_addr {
+        u16             call_id;
+        struct in_addr  sin_addr;
+};
+
+/************************************************************************
+ * Protocols supported by AF_PPPOX
+ */
 #define PX_PROTO_OE    0 /* Currently just PPPoE */
 #define PX_PROTO_OL2TP 1 /* Now L2TP also */
-#define PX_MAX_PROTO   2
-
-struct sockaddr_pppox { 
-       sa_family_t     sa_family;            /* address family, AF_PPPOX */ 
-       unsigned int    sa_protocol;          /* protocol identifier */ 
-       union{ 
-               struct pppoe_addr       pppoe; 
-       }sa_addr; 
+#define PX_PROTO_PPTP  2
+#define PX_MAX_PROTO   3
+
+struct sockaddr_pppox {
+        sa_family_t     sa_family;            /* address family, AF_PPPOX */
+        unsigned int    sa_protocol;          /* protocol identifier */
+        union {
+                struct pppoe_addr  pppoe;
+                struct pptp_addr   pptp;
+        } sa_addr;
 } __packed;
 
 /* The use of the above union isn't viable because the size of this
@@ -101,7 +111,7 @@ struct pppoe_tag {
         __be16 tag_type;
         __be16 tag_len;
         char tag_data[0];
-} __attribute ((packed));
+} __packed;
 
 /* Tag identifiers */
 #define PTT_EOL         __cpu_to_be16(0x0000)
@@ -150,15 +160,23 @@ struct pppoe_opt {
                                              relayed to (PPPoE relaying) */
 };
 
+struct pptp_opt {
+        struct pptp_addr src_addr;
+        struct pptp_addr dst_addr;
+        u32 ack_sent, ack_recv;
+        u32 seq_sent, seq_recv;
+        int ppp_flags;
+};
 #include <net/sock.h>
 
 struct pppox_sock {
         /* struct sock must be the first member of pppox_sock */
-        struct sock             sk;
-        struct ppp_channel      chan;
+        struct sock sk;
+        struct ppp_channel chan;
         struct pppox_sock       *next;    /* for hash table */
         union {
                 struct pppoe_opt pppoe;
+                struct pptp_opt  pptp;
         } proto;
         __be16                  num;
 };
diff --git a/include/net/gre.h b/include/net/gre.h
new file mode 100644
index 000000000000..82665474bcb7
--- /dev/null
+++ b/include/net/gre.h
@@ -0,0 +1,18 @@
+#ifndef __LINUX_GRE_H
+#define __LINUX_GRE_H
+
+#include <linux/skbuff.h>
+
+#define GREPROTO_CISCO          0
+#define GREPROTO_PPTP           1
+#define GREPROTO_MAX            2
+
+struct gre_protocol {
+        int  (*handler)(struct sk_buff *skb);
+        void (*err_handler)(struct sk_buff *skb, u32 info);
+};
+
+int gre_add_protocol(const struct gre_protocol *proto, u8 version);
+int gre_del_protocol(const struct gre_protocol *proto, u8 version);
+
+#endif