Commit eb1ac9ff authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Jakub Kicinski
Browse files

ipv6: anycast: Don't hold RTNL for IPV6_JOIN_ANYCAST. 



inet6_sk(sk)->ipv6_ac_list is protected by lock_sock().

In ipv6_sock_ac_join(), only __dev_get_by_index(), __dev_get_by_flags(),
and __in6_dev_get() require RTNL.

__dev_get_by_flags() is only used by ipv6_sock_ac_join() and can be
converted to RCU version.

Let's replace RCU version helper and drop RTNL from IPV6_JOIN_ANYCAST.

setsockopt_needs_rtnl() will be removed in the next patch.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250702230210.3115355-15-kuni1840@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 976fa9b2

include/linux/netdevice.h

+2 −2
Original line number Diff line number Diff line
@@ -3332,7 +3332,7 @@ int dev_get_iflink(const struct net_device *dev); 
int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb);

int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,

			  struct net_device_path_stack *stack);

struct net_device *__dev_get_by_flags(struct net *net, unsigned short flags,

struct net_device *dev_get_by_flags_rcu(struct net *net, unsigned short flags,

					unsigned short mask);

struct net_device *dev_get_by_name(struct net *net, const char *name);

struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);

net/core/dev.c

+18 −20
Original line number Diff line number Diff line
@@ -1267,33 +1267,31 @@ struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type) 
EXPORT_SYMBOL(dev_getfirstbyhwtype);



/**

 *	__dev_get_by_flags - find any device with given flags

 * dev_get_by_flags_rcu - find any device with given flags

 * @net: the applicable net namespace

 * @if_flags: IFF_* values

 * @mask: bitmask of bits in if_flags to check

 *

 *	Search for any interface with the given flags. Returns NULL if a device

 *	is not found or a pointer to the device. Must be called inside

 *	rtnl_lock(), and result refcount is unchanged.

 * Search for any interface with the given flags.

 *

 * Context: rcu_read_lock() must be held.

 * Returns: NULL if a device is not found or a pointer to the device.

 */



struct net_device *__dev_get_by_flags(struct net *net, unsigned short if_flags,

struct net_device *dev_get_by_flags_rcu(struct net *net, unsigned short if_flags,

					unsigned short mask)

{

	struct net_device *dev, *ret;



	ASSERT_RTNL();

	struct net_device *dev;



	ret = NULL;

	for_each_netdev(net, dev) {

		if (((dev->flags ^ if_flags) & mask) == 0) {

			ret = dev;

			break;

	for_each_netdev_rcu(net, dev) {

		if (((READ_ONCE(dev->flags) ^ if_flags) & mask) == 0) {

			dev_hold(dev);

			return dev;

		}

	}

	return ret;



	return NULL;

}

EXPORT_SYMBOL(__dev_get_by_flags);

EXPORT_IPV6_MOD(dev_get_by_flags_rcu);



/**

 *	dev_valid_name - check if name is okay for network device

net/ipv6/anycast.c

+14 −8
Original line number Diff line number Diff line
@@ -73,15 +73,13 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 
	struct inet6_dev *idev;

	int err = 0, ishost;



	ASSERT_RTNL();



	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))

		return -EPERM;

	if (ipv6_addr_is_multicast(addr))

		return -EINVAL;



	if (ifindex)

		dev = __dev_get_by_index(net, ifindex);

		dev = dev_get_by_index(net, ifindex);



	if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE)) {

		err = -EINVAL;
@@ -102,18 +100,22 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 
	if (ifindex == 0) {

		struct rt6_info *rt;



		rcu_read_lock();

		rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);

		if (rt) {

			dev = rt->dst.dev;

			dev = dst_dev(&rt->dst);

			dev_hold(dev);

			ip6_rt_put(rt);

		} else if (ishost) {

			rcu_read_unlock();

			err = -EADDRNOTAVAIL;

			goto error;

		} else {

			/* router, no matching interface: just pick one */

			dev = __dev_get_by_flags(net, IFF_UP,

			dev = dev_get_by_flags_rcu(net, IFF_UP,

						   IFF_UP | IFF_LOOPBACK);

		}

		rcu_read_unlock();

	}



	if (!dev) {
@@ -121,7 +123,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 
		goto error;

	}



	idev = __in6_dev_get(dev);

	idev = in6_dev_get(dev);

	if (!idev) {

		if (ifindex)

			err = -ENODEV;
@@ -144,7 +146,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 
		if (ishost)

			err = -EADDRNOTAVAIL;

		if (err)

			goto error;

			goto error_idev;

	}



	err = __ipv6_dev_ac_inc(idev, addr);
@@ -154,7 +156,11 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 
		pac = NULL;

	}



error_idev:

	in6_dev_put(idev);

error:

	dev_put(dev);



	if (pac)

		sock_kfree_s(sk, pac, sizeof(*pac));

	return err;

net/ipv6/ipv6_sockglue.c

+0 −4
Original line number Diff line number Diff line
@@ -119,10 +119,6 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk, 


static bool setsockopt_needs_rtnl(int optname)

{

	switch (optname) {

	case IPV6_JOIN_ANYCAST:

		return true;

	}

	return false;

}