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xfrm: add rcu protection to sk->sk_policy[]

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XFRM can deal with SYNACK messages, sent while listener socket
is not locked. We add proper rcu protection to __xfrm_sk_clone_policy()
and xfrm_sk_policy_lookup()

This might serve as the first step to remove xfrm.xfrm_policy_lock
use in fast path.

Fixes: fa76ce7328 ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2015-12-08 07:22:02 -08:00
committed by David S. Miller
parent 56f047305d
commit d188ba86dd
4 changed files with 42 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
net/xfrm/xfrm_policy.c
View File

@@ -1221,8 +1221,10 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
struct xfrm_policy *pol;
struct net *net = sock_net(sk);
rcu_read_lock();
read_lock_bh(&net->xfrm.xfrm_policy_lock);
if ((pol = sk->sk_policy[dir]) != NULL) {
pol = rcu_dereference(sk->sk_policy[dir]);
if (pol != NULL) {
bool match = xfrm_selector_match(&pol->selector, fl,
sk->sk_family);
int err = 0;
@@ -1246,6 +1248,7 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir,
}
out:
read_unlock_bh(&net->xfrm.xfrm_policy_lock);
rcu_read_unlock();
return pol;
}
@@ -1314,13 +1317,14 @@ int xfrm_sk_policy_insert(struct sock *sk, int dir, struct xfrm_policy *pol)
#endif
write_lock_bh(&net->xfrm.xfrm_policy_lock);
old_pol = sk->sk_policy[dir];
sk->sk_policy[dir] = pol;
old_pol = rcu_dereference_protected(sk->sk_policy[dir],
lockdep_is_held(&net->xfrm.xfrm_policy_lock));
if (pol) {
pol->curlft.add_time = get_seconds();
pol->index = xfrm_gen_index(net, XFRM_POLICY_MAX+dir, 0);
xfrm_sk_policy_link(pol, dir);
}
rcu_assign_pointer(sk->sk_policy[dir], pol);
if (old_pol) {
if (pol)
xfrm_policy_requeue(old_pol, pol);
@@ -1368,17 +1372,26 @@ static struct xfrm_policy *clone_policy(const struct xfrm_policy *old, int dir)
return newp;
}
int __xfrm_sk_clone_policy(struct sock *sk)
int __xfrm_sk_clone_policy(struct sock *sk, const struct sock *osk)
{
struct xfrm_policy *p0 = sk->sk_policy[0],
*p1 = sk->sk_policy[1];
const struct xfrm_policy *p;
struct xfrm_policy *np;
int i, ret = 0;
sk->sk_policy[0] = sk->sk_policy[1] = NULL;
if (p0 && (sk->sk_policy[0] = clone_policy(p0, 0)) == NULL)
return -ENOMEM;
if (p1 && (sk->sk_policy[1] = clone_policy(p1, 1)) == NULL)
return -ENOMEM;
return 0;
rcu_read_lock();
for (i = 0; i < 2; i++) {
p = rcu_dereference(osk->sk_policy[i]);
if (p) {
np = clone_policy(p, i);
if (unlikely(!np)) {
ret = -ENOMEM;
break;
}
rcu_assign_pointer(sk->sk_policy[i], np);
}
}
rcu_read_unlock();
return ret;
}
static int