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Commit 7a9bc9b8 authored by David S. Miller's avatar David S. Miller
Browse files

ipv4: Elide fib_validate_source() completely when possible. 



If rpfilter is off (or the SKB has an IPSEC path) and there are not
tclassid users, we don't have to do anything at all when
fib_validate_source() is invoked besides setting the itag to zero.

We monitor tclassid uses with a counter (modified only under RTNL and
marked __read_mostly) and we protect the fib_validate_source() real
work with a test against this counter and whether rpfilter is to be
done.

Having a way to know whether we need no tclassid processing or not
also opens the door for future optimized rpfilter algorithms that do
not perform full FIB lookups.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b8c84307

include/net/fib_rules.h

+1 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct fib_rules_ops { 
					     struct sk_buff *,

					     struct fib_rule_hdr *,

					     struct nlattr **);

	void			(*delete)(struct fib_rule *);

	int			(*compare)(struct fib_rule *,

					   struct fib_rule_hdr *,

					   struct nlattr **);

include/net/ip_fib.h

+5 −0
Original line number Diff line number Diff line
@@ -235,6 +235,11 @@ extern int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, 
			       u8 tos, int oif, struct net_device *dev,

			       struct in_device *idev, u32 *itag);

extern void fib_select_default(struct fib_result *res);

#ifdef CONFIG_IP_ROUTE_CLASSID

extern int fib_num_tclassid_users;

#else

#define fib_num_tclassid_users 0

#endif



/* Exported by fib_semantics.c */

extern int ip_fib_check_default(__be32 gw, struct net_device *dev);

net/core/fib_rules.c

+4 −0
Original line number Diff line number Diff line
@@ -151,6 +151,8 @@ static void fib_rules_cleanup_ops(struct fib_rules_ops *ops) 


	list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {

		list_del_rcu(&rule->list);

		if (ops->delete)

			ops->delete(rule);

		fib_rule_put(rule);

	}

}
@@ -499,6 +501,8 @@ static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) 


		notify_rule_change(RTM_DELRULE, rule, ops, nlh,

				   NETLINK_CB(skb).pid);

		if (ops->delete)

			ops->delete(rule);

		fib_rule_put(rule);

		flush_route_cache(ops);

		rules_ops_put(ops);

net/ipv4/fib_frontend.c

+24 −8
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/if_addr.h>

#include <linux/if_arp.h>

#include <linux/skbuff.h>

#include <linux/cache.h>

#include <linux/init.h>

#include <linux/list.h>

#include <linux/slab.h>
@@ -217,6 +218,10 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb) 
	return inet_select_addr(dev, ip_hdr(skb)->saddr, scope);

}



#ifdef CONFIG_IP_ROUTE_CLASSID

int fib_num_tclassid_users __read_mostly;

#endif



/* Given (packet source, input interface) and optional (dst, oif, tos):

 * - (main) check, that source is valid i.e. not broadcast or our local

 *   address.
@@ -225,11 +230,11 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb) 
 * - check, that packet arrived from expected physical interface.

 * called with rcu_read_lock()

 */

int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, u8 tos,

			int oif, struct net_device *dev, struct in_device *idev,

			u32 *itag)

static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,

				 u8 tos, int oif, struct net_device *dev,

				 int rpf, struct in_device *idev, u32 *itag)

{

	int ret, no_addr, rpf, accept_local;

	int ret, no_addr, accept_local;

	struct fib_result res;

	struct flowi4 fl4;

	struct net *net;
@@ -242,12 +247,9 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, u8 tos, 
	fl4.flowi4_tos = tos;

	fl4.flowi4_scope = RT_SCOPE_UNIVERSE;



	no_addr = rpf = accept_local = 0;

	no_addr = accept_local = 0;

	no_addr = idev->ifa_list == NULL;



	/* Ignore rp_filter for packets protected by IPsec. */

	rpf = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);



	accept_local = IN_DEV_ACCEPT_LOCAL(idev);

	fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;
@@ -303,6 +305,20 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, u8 tos, 
	return -EXDEV;

}



/* Ignore rp_filter for packets protected by IPsec. */

int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,

			u8 tos, int oif, struct net_device *dev,

			struct in_device *idev, u32 *itag)

{

	int r = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(idev);



	if (!r && !fib_num_tclassid_users) {

		*itag = 0;

		return 0;

	}

	return __fib_validate_source(skb, src, dst, tos, oif, dev, r, idev, itag);

}



static inline __be32 sk_extract_addr(struct sockaddr *addr)

{

	return ((struct sockaddr_in *) addr)->sin_addr.s_addr;

net/ipv4/fib_rules.c

+15 −1
Original line number Diff line number Diff line
@@ -169,8 +169,11 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 
		rule4->dst = nla_get_be32(tb[FRA_DST]);



#ifdef CONFIG_IP_ROUTE_CLASSID

	if (tb[FRA_FLOW])

	if (tb[FRA_FLOW]) {

		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);

		if (rule4->tclassid)

			fib_num_tclassid_users++;

	}

#endif



	rule4->src_len = frh->src_len;
@@ -184,6 +187,16 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 
	return err;

}



static void fib4_rule_delete(struct fib_rule *rule)

{

#ifdef CONFIG_IP_ROUTE_CLASSID

	struct fib4_rule *rule4 = (struct fib4_rule *) rule;



	if (rule4->tclassid)

		fib_num_tclassid_users--;

#endif

}



static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,

			     struct nlattr **tb)

{
@@ -256,6 +269,7 @@ static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = { 
	.action		= fib4_rule_action,

	.match		= fib4_rule_match,

	.configure	= fib4_rule_configure,

	.delete		= fib4_rule_delete,

	.compare	= fib4_rule_compare,

	.fill		= fib4_rule_fill,

	.default_pref	= fib_default_rule_pref,