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gre: Remove support for sharing GRE protocol hook.
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Support for sharing GREPROTO_CISCO port was added so that
OVS gre port and kernel GRE devices can co-exist. After
flow-based tunneling patches OVS GRE protocol processing
is completely moved to ip_gre module. so there is no need
for GRE protocol hook. Following patch consolidates
GRE protocol related functions into ip_gre module.

Signed-off-by: Pravin B Shelar <[email protected]>
Acked-by: Thomas Graf <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@davem330
Pravin B Shelar authored and davem330 committed Aug 10, 2015
1 parent b2acd1d commit 9f57c67
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Showing 3 changed files with 206 additions and 290 deletions.
80 changes: 6 additions & 74 deletions include/net/gre.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,12 @@
#include <linux/skbuff.h>
#include <net/ip_tunnels.h>

struct gre_base_hdr {
__be16 flags;
__be16 protocol;
};
#define GRE_HEADER_SECTION 4

#define GREPROTO_CISCO 0
#define GREPROTO_PPTP 1
#define GREPROTO_MAX 2
Expand All @@ -14,83 +20,9 @@ struct gre_protocol {
void (*err_handler)(struct sk_buff *skb, u32 info);
};

struct gre_base_hdr {
__be16 flags;
__be16 protocol;
};
#define GRE_HEADER_SECTION 4

int gre_add_protocol(const struct gre_protocol *proto, u8 version);
int gre_del_protocol(const struct gre_protocol *proto, u8 version);

struct gre_cisco_protocol {
int (*handler)(struct sk_buff *skb, const struct tnl_ptk_info *tpi);
int (*err_handler)(struct sk_buff *skb, u32 info,
const struct tnl_ptk_info *tpi);
u8 priority;
};

int gre_cisco_register(struct gre_cisco_protocol *proto);
int gre_cisco_unregister(struct gre_cisco_protocol *proto);

struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
u8 name_assign_type);

static inline int ip_gre_calc_hlen(__be16 o_flags)
{
int addend = 4;

if (o_flags&TUNNEL_CSUM)
addend += 4;
if (o_flags&TUNNEL_KEY)
addend += 4;
if (o_flags&TUNNEL_SEQ)
addend += 4;
return addend;
}

static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
{
__be16 tflags = 0;

if (flags & GRE_CSUM)
tflags |= TUNNEL_CSUM;
if (flags & GRE_ROUTING)
tflags |= TUNNEL_ROUTING;
if (flags & GRE_KEY)
tflags |= TUNNEL_KEY;
if (flags & GRE_SEQ)
tflags |= TUNNEL_SEQ;
if (flags & GRE_STRICT)
tflags |= TUNNEL_STRICT;
if (flags & GRE_REC)
tflags |= TUNNEL_REC;
if (flags & GRE_VERSION)
tflags |= TUNNEL_VERSION;

return tflags;
}

static inline __be16 tnl_flags_to_gre_flags(__be16 tflags)
{
__be16 flags = 0;

if (tflags & TUNNEL_CSUM)
flags |= GRE_CSUM;
if (tflags & TUNNEL_ROUTING)
flags |= GRE_ROUTING;
if (tflags & TUNNEL_KEY)
flags |= GRE_KEY;
if (tflags & TUNNEL_SEQ)
flags |= GRE_SEQ;
if (tflags & TUNNEL_STRICT)
flags |= GRE_STRICT;
if (tflags & TUNNEL_REC)
flags |= GRE_REC;
if (tflags & TUNNEL_VERSION)
flags |= GRE_VERSION;

return flags;
}

#endif
201 changes: 1 addition & 200 deletions net/ipv4/gre_demux.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@
#include <net/xfrm.h>

static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX];

int gre_add_protocol(const struct gre_protocol *proto, u8 version)
{
Expand Down Expand Up @@ -61,163 +60,6 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version)
}
EXPORT_SYMBOL_GPL(gre_del_protocol);

static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err)
{
const struct gre_base_hdr *greh;
__be32 *options;
int hdr_len;

if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
return -EINVAL;

tpi->flags = gre_flags_to_tnl_flags(greh->flags);
hdr_len = ip_gre_calc_hlen(tpi->flags);

if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
tpi->proto = greh->protocol;

options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
if (skb_checksum_simple_validate(skb)) {
*csum_err = true;
return -EINVAL;
}

skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
null_compute_pseudo);

options++;
}

if (greh->flags & GRE_KEY) {
tpi->key = *options;
options++;
} else
tpi->key = 0;

if (unlikely(greh->flags & GRE_SEQ)) {
tpi->seq = *options;
options++;
} else
tpi->seq = 0;

/* WCCP version 1 and 2 protocol decoding.
* - Change protocol to IP
* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
*/
if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
tpi->proto = htons(ETH_P_IP);
if ((*(u8 *)options & 0xF0) != 0x40) {
hdr_len += 4;
if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;
}
}

return iptunnel_pull_header(skb, hdr_len, tpi->proto);
}

static int gre_cisco_rcv(struct sk_buff *skb)
{
struct tnl_ptk_info tpi;
int i;
bool csum_err = false;

#ifdef CONFIG_NET_IPGRE_BROADCAST
if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
/* Looped back packet, drop it! */
if (rt_is_output_route(skb_rtable(skb)))
goto drop;
}
#endif

if (parse_gre_header(skb, &tpi, &csum_err) < 0)
goto drop;

rcu_read_lock();
for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
struct gre_cisco_protocol *proto;
int ret;

proto = rcu_dereference(gre_cisco_proto_list[i]);
if (!proto)
continue;
ret = proto->handler(skb, &tpi);
if (ret == PACKET_RCVD) {
rcu_read_unlock();
return 0;
}
}
rcu_read_unlock();

icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
drop:
kfree_skb(skb);
return 0;
}

static void gre_cisco_err(struct sk_buff *skb, u32 info)
{
/* All the routers (except for Linux) return only
* 8 bytes of packet payload. It means, that precise relaying of
* ICMP in the real Internet is absolutely infeasible.
*
* Moreover, Cisco "wise men" put GRE key to the third word
* in GRE header. It makes impossible maintaining even soft
* state for keyed
* GRE tunnels with enabled checksum. Tell them "thank you".
*
* Well, I wonder, rfc1812 was written by Cisco employee,
* what the hell these idiots break standards established
* by themselves???
*/

const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct tnl_ptk_info tpi;
bool csum_err = false;
int i;

if (parse_gre_header(skb, &tpi, &csum_err)) {
if (!csum_err) /* ignore csum errors. */
return;
}

if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
skb->dev->ifindex, 0, IPPROTO_GRE, 0);
return;
}
if (type == ICMP_REDIRECT) {
ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
IPPROTO_GRE, 0);
return;
}

rcu_read_lock();
for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
struct gre_cisco_protocol *proto;

proto = rcu_dereference(gre_cisco_proto_list[i]);
if (!proto)
continue;

if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
goto out;

}
out:
rcu_read_unlock();
}

static int gre_rcv(struct sk_buff *skb)
{
const struct gre_protocol *proto;
Expand Down Expand Up @@ -268,60 +110,19 @@ static const struct net_protocol net_gre_protocol = {
.netns_ok = 1,
};

static const struct gre_protocol ipgre_protocol = {
.handler = gre_cisco_rcv,
.err_handler = gre_cisco_err,
};

int gre_cisco_register(struct gre_cisco_protocol *newp)
{
struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
&gre_cisco_proto_list[newp->priority];

return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(gre_cisco_register);

int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
{
struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
&gre_cisco_proto_list[del_proto->priority];
int ret;

ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;

if (ret)
return ret;

synchronize_net();
return 0;
}
EXPORT_SYMBOL_GPL(gre_cisco_unregister);

static int __init gre_init(void)
{
pr_info("GRE over IPv4 demultiplexor driver\n");

if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
pr_err("can't add protocol\n");
goto err;
return -EAGAIN;
}

if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
pr_info("%s: can't add ipgre handler\n", __func__);
goto err_gre;
}

return 0;
err_gre:
inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
err:
return -EAGAIN;
}

static void __exit gre_exit(void)
{
gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
}

Expand Down
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