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ipv6: lockless IPV6_MTU implementation

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np->frag_size can be read/written without holding socket lock.

Add missing annotations and make IPV6_MTU setsockopt() lockless.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2023-09-12 16:02:02 +00:00 committed by David S. Miller
parent 2da23eb07c
commit 15f926c445
2 changed files with 18 additions and 16 deletions
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19
net/ipv6/ip6_output.c
View file

@ -881,9 +881,11 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
mtu = IPV6_MIN_MTU;
}
if (np && np->frag_size < mtu) {
if (np->frag_size)
mtu = np->frag_size;
if (np) {
u32 frag_size = READ_ONCE(np->frag_size);
if (frag_size && frag_size < mtu)
mtu = frag_size;
}
if (mtu < hlen + sizeof(struct frag_hdr) + 8)
goto fail_toobig;
@ -1392,7 +1394,7 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
struct rt6_info *rt)
{
struct ipv6_pinfo *np = inet6_sk(sk);
unsigned int mtu;
unsigned int mtu, frag_size;
struct ipv6_txoptions *nopt, *opt = ipc6->opt;
/* callers pass dst together with a reference, set it first so
@ -1441,10 +1443,11 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
else
mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst));
if (np->frag_size < mtu) {
if (np->frag_size)
mtu = np->frag_size;
}
frag_size = READ_ONCE(np->frag_size);
if (frag_size && frag_size < mtu)
mtu = frag_size;
cork->base.fragsize = mtu;
cork->base.gso_size = ipc6->gso_size;
cork->base.tx_flags = 0;

15
net/ipv6/ipv6_sockglue.c
View file

@ -441,6 +441,13 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
WRITE_ONCE(np->mcast_hops,
val == -1 ? IPV6_DEFAULT_MCASTHOPS : val);
return 0;
case IPV6_MTU:
if (optlen < sizeof(int))
return -EINVAL;
if (val && val < IPV6_MIN_MTU)
return -EINVAL;
WRITE_ONCE(np->frag_size, val);
return 0;
}
if (needs_rtnl)
rtnl_lock();
@ -910,14 +917,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
np->pmtudisc = val;
retv = 0;
break;
case IPV6_MTU:
if (optlen < sizeof(int))
goto e_inval;
if (val && val < IPV6_MIN_MTU)
goto e_inval;
np->frag_size = val;
retv = 0;
break;
case IPV6_RECVERR:
if (optlen < sizeof(int))
goto e_inval;