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netfilter: move reroute indirection to struct nf_ipv6_ops
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We cannot make a direct call to nf_ip6_reroute() because that would result
in autoloading the 'ipv6' module because of symbol dependencies.
Therefore, define reroute indirection in nf_ipv6_ops where this really
belongs to.

For IPv4, we can indeed make a direct function call, which is faster,
given IPv4 is built-in in the networking code by default. Still,
CONFIG_INET=n and CONFIG_NETFILTER=y is possible, so define empty inline
stub for IPv4 in such case.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ummakynes
ummakynes committed Jan 8, 2018
1 parent 3f87c08 commit ce388f4
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Showing 8 changed files with 39 additions and 19 deletions.
3 changes: 1 addition & 2 deletions include/linux/netfilter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -311,8 +311,6 @@ struct nf_queue_entry;

struct nf_afinfo {
unsigned short family;
int (*reroute)(struct net *net, struct sk_buff *skb,
const struct nf_queue_entry *entry);
int route_key_size;
};

Expand All @@ -331,6 +329,7 @@ __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
u_int8_t protocol, unsigned short family);
int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
bool strict, unsigned short family);
int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry);

int nf_register_afinfo(const struct nf_afinfo *afinfo);
void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
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8 changes: 8 additions & 0 deletions include/linux/netfilter_ipv4.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@ struct ip_rt_info {

int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned addr_type);

struct nf_queue_entry;

#ifdef CONFIG_INET
__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol);
Expand All @@ -26,6 +28,7 @@ __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
u_int8_t protocol);
int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
bool strict);
int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry);
#else
static inline __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol)
Expand All @@ -45,6 +48,11 @@ static inline int nf_ip_route(struct net *net, struct dst_entry **dst,
{
return -EOPNOTSUPP;
}
static inline int nf_ip_reroute(struct sk_buff *skb,
const struct nf_queue_entry *entry)
{
return -EOPNOTSUPP;
}
#endif /* CONFIG_INET */

#endif /*__LINUX_IP_NETFILTER_H*/
3 changes: 3 additions & 0 deletions include/linux/netfilter_ipv6.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@ struct ip6_rt_info {
u_int32_t mark;
};

struct nf_queue_entry;

/*
* Hook functions for ipv6 to allow xt_* modules to be built-in even
* if IPv6 is a module.
Expand All @@ -35,6 +37,7 @@ struct nf_ipv6_ops {
u_int8_t protocol);
int (*route)(struct net *net, struct dst_entry **dst, struct flowi *fl,
bool strict);
int (*reroute)(struct sk_buff *skb, const struct nf_queue_entry *entry);
};

#ifdef CONFIG_NETFILTER
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7 changes: 0 additions & 7 deletions net/bridge/netfilter/nf_tables_bridge.c
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Original file line number Diff line number Diff line change
Expand Up @@ -95,15 +95,8 @@ static const struct nf_chain_type filter_bridge = {
},
};

static int nf_br_reroute(struct net *net, struct sk_buff *skb,
const struct nf_queue_entry *entry)
{
return 0;
}

static const struct nf_afinfo nf_br_afinfo = {
.family = AF_BRIDGE,
.reroute = nf_br_reroute,
.route_key_size = 0,
};

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8 changes: 4 additions & 4 deletions net/ipv4/netfilter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -80,8 +80,7 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_t
}
EXPORT_SYMBOL(ip_route_me_harder);

static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
const struct nf_queue_entry *entry)
int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry)
{
const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);

Expand All @@ -92,10 +91,12 @@ static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
skb->mark == rt_info->mark &&
iph->daddr == rt_info->daddr &&
iph->saddr == rt_info->saddr))
return ip_route_me_harder(net, skb, RTN_UNSPEC);
return ip_route_me_harder(entry->state.net, skb,
RTN_UNSPEC);
}
return 0;
}
EXPORT_SYMBOL_GPL(nf_ip_reroute);

__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol)
Expand Down Expand Up @@ -163,7 +164,6 @@ EXPORT_SYMBOL_GPL(nf_ip_route);

static const struct nf_afinfo nf_ip_afinfo = {
.family = AF_INET,
.reroute = nf_ip_reroute,
.route_key_size = sizeof(struct ip_rt_info),
};

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6 changes: 3 additions & 3 deletions net/ipv6/netfilter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
}
EXPORT_SYMBOL(ip6_route_me_harder);

static int nf_ip6_reroute(struct net *net, struct sk_buff *skb,
static int nf_ip6_reroute(struct sk_buff *skb,
const struct nf_queue_entry *entry)
{
struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
Expand All @@ -78,7 +78,7 @@ static int nf_ip6_reroute(struct net *net, struct sk_buff *skb,
if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
!ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
skb->mark != rt_info->mark)
return ip6_route_me_harder(net, skb);
return ip6_route_me_harder(entry->state.net, skb);
}
return 0;
}
Expand Down Expand Up @@ -171,11 +171,11 @@ static const struct nf_ipv6_ops ipv6ops = {
.checksum = nf_ip6_checksum,
.checksum_partial = nf_ip6_checksum_partial,
.route = nf_ip6_route,
.reroute = nf_ip6_reroute,
};

static const struct nf_afinfo nf_ip6_afinfo = {
.family = AF_INET6,
.reroute = nf_ip6_reroute,
.route_key_size = sizeof(struct ip6_rt_info),
};

Expand Down
4 changes: 1 addition & 3 deletions net/netfilter/nf_queue.c
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Original file line number Diff line number Diff line change
Expand Up @@ -266,7 +266,6 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
const struct nf_hook_entry *hook_entry;
const struct nf_hook_entries *hooks;
struct sk_buff *skb = entry->skb;
const struct nf_afinfo *afinfo;
const struct net *net;
unsigned int i;
int err;
Expand All @@ -293,8 +292,7 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);

if (verdict == NF_ACCEPT) {
afinfo = nf_get_afinfo(entry->state.pf);
if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0)
if (nf_reroute(skb, entry) < 0)
verdict = NF_DROP;
}

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19 changes: 19 additions & 0 deletions net/netfilter/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_queue.h>

__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol,
Expand Down Expand Up @@ -69,3 +70,21 @@ int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
return ret;
}
EXPORT_SYMBOL_GPL(nf_route);

int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry)
{
const struct nf_ipv6_ops *v6ops;
int ret = 0;

switch (entry->state.pf) {
case AF_INET:
ret = nf_ip_reroute(skb, entry);
break;
case AF_INET6:
v6ops = rcu_dereference(nf_ipv6_ops);
if (v6ops)
ret = v6ops->reroute(skb, entry);
break;
}
return ret;
}

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