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Commit 97cc931f authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ipv6-dgram-dst-cache' 



Martin KaFai Lau says:

====================
ipv6: datagram: Update dst cache of a connected udp sk during pmtu update

v2:
~ Protect __sk_dst_get() operations with rcu_read_lock in
  release_cb() because another thread may do ip6_dst_store()
  for a udp sk without taking the sk lock (e.g. in sendmsg).
~ Do a ipv6_addr_v4mapped(&sk->sk_v6_daddr) check before
  calling ip6_datagram_dst_update() in patch 3 and 4.  It is
  similar to how __ip6_datagram_connect handles it.
~ One fix in ip6_datagram_dst_update() in patch 2.  It needs
  to check (np->flow_label & IPV6_FLOWLABEL_MASK) before
  doing fl6_sock_lookup.  I was confused with the naming
  of IPV6_FLOWLABEL_MASK and IPV6_FLOWINFO_MASK.
~ Check dst->obsolete just on the safe side, although I think it
  should at least have DST_OBSOLETE_FORCE_CHK by now.
~ Add Fixes tag to patch 3 and 4
~ Add some points from the previous discussion about holding
  sk lock to the commit message in patch 3.

v1:
There is a case in connected UDP socket such that
getsockopt(IPV6_MTU) will return a stale MTU value. The reproducible
sequence could be the following:
1. Create a connected UDP socket
2. Send some datagrams out
3. Receive a ICMPV6_PKT_TOOBIG
4. No new outgoing datagrams to trigger the sk_dst_check()
   logic to update the sk->sk_dst_cache.
5. getsockopt(IPV6_MTU) returns the mtu from the invalid
   sk->sk_dst_cache instead of the newly created RTF_CACHE clone.

Patch 1 and 2 are the prep work.
Patch 3 and 4 are the fixes.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents f1d0540d e646b657

include/net/ipv6.h

+2 −0
Original line number Diff line number Diff line
@@ -959,6 +959,8 @@ int compat_ipv6_getsockopt(struct sock *sk, int level, int optname, 
int ip6_datagram_connect(struct sock *sk, struct sockaddr *addr, int addr_len);

int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr *addr,

				 int addr_len);

int ip6_datagram_dst_update(struct sock *sk, bool fix_sk_saddr);

void ip6_datagram_release_cb(struct sock *sk);



int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len,

		    int *addr_len);

net/ipv6/datagram.c

+106 −63
Original line number Diff line number Diff line
@@ -40,18 +40,114 @@ static bool ipv6_mapped_addr_any(const struct in6_addr *a) 
	return ipv6_addr_v4mapped(a) && (a->s6_addr32[3] == 0);

}



static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)

static void ip6_datagram_flow_key_init(struct flowi6 *fl6, struct sock *sk)

{

	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;

	struct inet_sock *inet = inet_sk(sk);

	struct ipv6_pinfo *np = inet6_sk(sk);

	struct in6_addr	*daddr, *final_p, final;

	struct dst_entry	*dst;

	struct flowi6		fl6;



	memset(fl6, 0, sizeof(*fl6));

	fl6->flowi6_proto = sk->sk_protocol;

	fl6->daddr = sk->sk_v6_daddr;

	fl6->saddr = np->saddr;

	fl6->flowi6_oif = sk->sk_bound_dev_if;

	fl6->flowi6_mark = sk->sk_mark;

	fl6->fl6_dport = inet->inet_dport;

	fl6->fl6_sport = inet->inet_sport;

	fl6->flowlabel = np->flow_label;



	if (!fl6->flowi6_oif)

		fl6->flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;



	if (!fl6->flowi6_oif && ipv6_addr_is_multicast(&fl6->daddr))

		fl6->flowi6_oif = np->mcast_oif;



	security_sk_classify_flow(sk, flowi6_to_flowi(fl6));

}



int ip6_datagram_dst_update(struct sock *sk, bool fix_sk_saddr)

{

	struct ip6_flowlabel *flowlabel = NULL;

	struct in6_addr *final_p, final;

	struct ipv6_txoptions *opt;

	struct dst_entry *dst;

	struct inet_sock *inet = inet_sk(sk);

	struct ipv6_pinfo *np = inet6_sk(sk);

	struct flowi6 fl6;

	int err = 0;



	if (np->sndflow && (np->flow_label & IPV6_FLOWLABEL_MASK)) {

		flowlabel = fl6_sock_lookup(sk, np->flow_label);

		if (!flowlabel)

			return -EINVAL;

	}

	ip6_datagram_flow_key_init(&fl6, sk);



	rcu_read_lock();

	opt = flowlabel ? flowlabel->opt : rcu_dereference(np->opt);

	final_p = fl6_update_dst(&fl6, opt, &final);

	rcu_read_unlock();



	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);

	if (IS_ERR(dst)) {

		err = PTR_ERR(dst);

		goto out;

	}



	if (fix_sk_saddr) {

		if (ipv6_addr_any(&np->saddr))

			np->saddr = fl6.saddr;



		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {

			sk->sk_v6_rcv_saddr = fl6.saddr;

			inet->inet_rcv_saddr = LOOPBACK4_IPV6;

			if (sk->sk_prot->rehash)

				sk->sk_prot->rehash(sk);

		}

	}



	ip6_dst_store(sk, dst,

		      ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr) ?

		      &sk->sk_v6_daddr : NULL,

#ifdef CONFIG_IPV6_SUBTREES

		      ipv6_addr_equal(&fl6.saddr, &np->saddr) ?

		      &np->saddr :

#endif

		      NULL);



out:

	fl6_sock_release(flowlabel);

	return err;

}



void ip6_datagram_release_cb(struct sock *sk)

{

	struct dst_entry *dst;



	if (ipv6_addr_v4mapped(&sk->sk_v6_daddr))

		return;



	rcu_read_lock();

	dst = __sk_dst_get(sk);

	if (!dst || !dst->obsolete ||

	    dst->ops->check(dst, inet6_sk(sk)->dst_cookie)) {

		rcu_read_unlock();

		return;

	}

	rcu_read_unlock();



	ip6_datagram_dst_update(sk, false);

}

EXPORT_SYMBOL_GPL(ip6_datagram_release_cb);



static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)

{

	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;

	struct inet_sock	*inet = inet_sk(sk);

	struct ipv6_pinfo	*np = inet6_sk(sk);

	struct in6_addr		*daddr;

	int			addr_type;

	int			err;

	__be32			fl6_flowlabel = 0;



	if (usin->sin6_family == AF_INET) {

		if (__ipv6_only_sock(sk))
@@ -66,15 +162,8 @@ static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int a 
	if (usin->sin6_family != AF_INET6)

		return -EAFNOSUPPORT;



	memset(&fl6, 0, sizeof(fl6));

	if (np->sndflow) {

		fl6.flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;

		if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {

			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);

			if (!flowlabel)

				return -EINVAL;

		}

	}

	if (np->sndflow)

		fl6_flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;



	addr_type = ipv6_addr_type(&usin->sin6_addr);
@@ -145,7 +234,7 @@ static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int a 
	}



	sk->sk_v6_daddr = *daddr;

	np->flow_label = fl6.flowlabel;

	np->flow_label = fl6_flowlabel;



	inet->inet_dport = usin->sin6_port;
@@ -154,59 +243,13 @@ static int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int a 
	 *	destination cache for it.

	 */



	fl6.flowi6_proto = sk->sk_protocol;

	fl6.daddr = sk->sk_v6_daddr;

	fl6.saddr = np->saddr;

	fl6.flowi6_oif = sk->sk_bound_dev_if;

	fl6.flowi6_mark = sk->sk_mark;

	fl6.fl6_dport = inet->inet_dport;

	fl6.fl6_sport = inet->inet_sport;



	if (!fl6.flowi6_oif)

		fl6.flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;



	if (!fl6.flowi6_oif && (addr_type&IPV6_ADDR_MULTICAST))

		fl6.flowi6_oif = np->mcast_oif;



	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));



	rcu_read_lock();

	opt = flowlabel ? flowlabel->opt : rcu_dereference(np->opt);

	final_p = fl6_update_dst(&fl6, opt, &final);

	rcu_read_unlock();



	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);

	err = 0;

	if (IS_ERR(dst)) {

		err = PTR_ERR(dst);

	err = ip6_datagram_dst_update(sk, true);

	if (err)

		goto out;

	}



	/* source address lookup done in ip6_dst_lookup */



	if (ipv6_addr_any(&np->saddr))

		np->saddr = fl6.saddr;



	if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {

		sk->sk_v6_rcv_saddr = fl6.saddr;

		inet->inet_rcv_saddr = LOOPBACK4_IPV6;

		if (sk->sk_prot->rehash)

			sk->sk_prot->rehash(sk);

	}



	ip6_dst_store(sk, dst,

		      ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr) ?

		      &sk->sk_v6_daddr : NULL,

#ifdef CONFIG_IPV6_SUBTREES

		      ipv6_addr_equal(&fl6.saddr, &np->saddr) ?

		      &np->saddr :

#endif

		      NULL);



	sk->sk_state = TCP_ESTABLISHED;

	sk_set_txhash(sk);

out:

	fl6_sock_release(flowlabel);

	return err;

}

net/ipv6/route.c

+12 −0
Original line number Diff line number Diff line
@@ -1418,8 +1418,20 @@ EXPORT_SYMBOL_GPL(ip6_update_pmtu); 


void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu)

{

	struct dst_entry *dst;



	ip6_update_pmtu(skb, sock_net(sk), mtu,

			sk->sk_bound_dev_if, sk->sk_mark);



	dst = __sk_dst_get(sk);

	if (!dst || !dst->obsolete ||

	    dst->ops->check(dst, inet6_sk(sk)->dst_cookie))

		return;



	bh_lock_sock(sk);

	if (!sock_owned_by_user(sk) && !ipv6_addr_v4mapped(&sk->sk_v6_daddr))

		ip6_datagram_dst_update(sk, false);

	bh_unlock_sock(sk);

}

EXPORT_SYMBOL_GPL(ip6_sk_update_pmtu);

net/ipv6/udp.c

+1 −0
Original line number Diff line number Diff line
@@ -1539,6 +1539,7 @@ struct proto udpv6_prot = { 
	.sendmsg	   = udpv6_sendmsg,

	.recvmsg	   = udpv6_recvmsg,

	.backlog_rcv	   = __udpv6_queue_rcv_skb,

	.release_cb	   = ip6_datagram_release_cb,

	.hash		   = udp_lib_hash,

	.unhash		   = udp_lib_unhash,

	.rehash		   = udp_v6_rehash,