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ipv6: lockless IPV6_UNICAST_HOPS implementation

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Some np->hop_limit accesses are racy, when socket lock is not held.

Add missing annotations and switch to full lockless implementation.

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 16:01:59 +00:00 committed by David S. Miller
parent f2fa1c812c
commit b0adfba7ee
6 changed files with 16 additions and 24 deletions
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12
include/linux/ipv6.h
View file

@ -213,17 +213,7 @@ struct ipv6_pinfo {
__be32 flow_label;
__u32 frag_size;
/*
* Packed in 16bits.
* Omit one shift by putting the signed field at MSB.
*/
#if defined(__BIG_ENDIAN_BITFIELD)
__s16 hop_limit:9;
__u16 __unused_1:7;
#else
__u16 __unused_1:7;
__s16 hop_limit:9;
#endif
s16 hop_limit;
#if defined(__BIG_ENDIAN_BITFIELD)
/* Packed in 16bits. */

2
include/net/ipv6.h
View file

@ -916,7 +916,7 @@ static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,
if (ipv6_addr_is_multicast(&fl6->daddr))
hlimit = np->mcast_hops;
else
hlimit = np->hop_limit;
hlimit = READ_ONCE(np->hop_limit);
if (hlimit < 0)
hlimit = ip6_dst_hoplimit(dst);
return hlimit;

2
net/ipv6/ip6_output.c
View file

@ -309,7 +309,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
* Fill in the IPv6 header
*/
if (np)
hlimit = np->hop_limit;
hlimit = READ_ONCE(np->hop_limit);
if (hlimit < 0)
hlimit = ip6_dst_hoplimit(dst);

20
net/ipv6/ipv6_sockglue.c
View file

@ -415,6 +415,16 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
if (ip6_mroute_opt(optname))
return ip6_mroute_setsockopt(sk, optname, optval, optlen);
/* Handle options that can be set without locking the socket. */
switch (optname) {
case IPV6_UNICAST_HOPS:
if (optlen < sizeof(int))
return -EINVAL;
if (val > 255 || val < -1)
return -EINVAL;
WRITE_ONCE(np->hop_limit, val);
return 0;
}
if (needs_rtnl)
rtnl_lock();
sockopt_lock_sock(sk);
@ -733,14 +743,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
}
break;
}
case IPV6_UNICAST_HOPS:
if (optlen < sizeof(int))
goto e_inval;
if (val > 255 || val < -1)
goto e_inval;
np->hop_limit = val;
retv = 0;
break;
case IPV6_MULTICAST_HOPS:
if (sk->sk_type == SOCK_STREAM)
@ -1347,7 +1349,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
struct dst_entry *dst;
if (optname == IPV6_UNICAST_HOPS)
val = np->hop_limit;
val = READ_ONCE(np->hop_limit);
else
val = np->mcast_hops;

2
net/ipv6/mcast.c
View file

@ -1716,7 +1716,7 @@ static void ip6_mc_hdr(const struct sock *sk, struct sk_buff *skb,
hdr->payload_len = htons(len);
hdr->nexthdr = proto;
hdr->hop_limit = inet6_sk(sk)->hop_limit;
hdr->hop_limit = READ_ONCE(inet6_sk(sk)->hop_limit);
hdr->saddr = *saddr;
hdr->daddr = *daddr;

2
net/ipv6/ndisc.c
View file

@ -500,7 +500,7 @@ void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr,
csum_partial(icmp6h,
skb->len, 0));
ip6_nd_hdr(skb, saddr, daddr, inet6_sk(sk)->hop_limit, skb->len);
ip6_nd_hdr(skb, saddr, daddr, READ_ONCE(inet6_sk(sk)->hop_limit), skb->len);
rcu_read_lock();
idev = __in6_dev_get(dst->dev);