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

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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: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250702230210.3115355-15-kuni1840@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2025-07-02 16:01:31 -07:00 • committed by Jakub Kicinski
parent 976fa9b205
commit eb1ac9ff6c
4 changed files with 34 additions and 34 deletions
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4
include/linux/netdevice.h
View file

@ -3332,8 +3332,8 @@ 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,
unsigned short mask);
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);
struct net_device *__dev_get_by_name(struct net *net, const char *name);

38
net/core/dev.c
View file

@ -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
* @net: the applicable net namespace
* @if_flags: IFF_* values
* @mask: bitmask of bits in if_flags to check
* 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,
unsigned short mask)
struct net_device *dev_get_by_flags_rcu(struct net *net, unsigned short if_flags,
unsigned short mask)
{
struct net_device *dev, *ret;
struct net_device *dev;
ASSERT_RTNL();
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

22
net/ipv6/anycast.c
View file

@ -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,
IFF_UP | IFF_LOOPBACK);
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;

4
net/ipv6/ipv6_sockglue.c
View file

@ -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;
}