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authorEric Dumazet <edumazet@google.com>2023-09-12 19:02:01 +0300
committerDavid S. Miller <davem@davemloft.net>2023-09-15 12:33:46 +0300
commit2da23eb07c91241d962f3ff05565065484cd8929 (patch)
tree921417255db7f2389304c5f21aac9c828b58caa8 /net/ipv6
parentd986f52124e062753e33b6fe303be5904a997eac (diff)
downloadlinux-2da23eb07c91241d962f3ff05565065484cd8929.tar.xz
ipv6: lockless IPV6_MULTICAST_HOPS implementation
This fixes data-races around np->mcast_hops, and make IPV6_MULTICAST_HOPS lockless. Note that np->mcast_hops is never negative, thus can fit an u8 field instead of s16. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/ipv6_sockglue.c28
-rw-r--r--net/ipv6/tcp_ipv6.c3
2 files changed, 17 insertions, 14 deletions
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 755fac85a120..5fff19a87c75 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -431,6 +431,16 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
return -EINVAL;
inet6_assign_bit(MC6_LOOP, sk, valbool);
return 0;
+ case IPV6_MULTICAST_HOPS:
+ if (sk->sk_type == SOCK_STREAM)
+ return retv;
+ if (optlen < sizeof(int))
+ return -EINVAL;
+ if (val > 255 || val < -1)
+ return -EINVAL;
+ WRITE_ONCE(np->mcast_hops,
+ val == -1 ? IPV6_DEFAULT_MCASTHOPS : val);
+ return 0;
}
if (needs_rtnl)
rtnl_lock();
@@ -751,16 +761,6 @@ done:
break;
}
- case IPV6_MULTICAST_HOPS:
- if (sk->sk_type == SOCK_STREAM)
- break;
- if (optlen < sizeof(int))
- goto e_inval;
- if (val > 255 || val < -1)
- goto e_inval;
- np->mcast_hops = (val == -1 ? IPV6_DEFAULT_MCASTHOPS : val);
- retv = 0;
- break;
case IPV6_UNICAST_IF:
{
@@ -1180,7 +1180,8 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
put_cmsg(&msg, SOL_IPV6, IPV6_PKTINFO, sizeof(src_info), &src_info);
}
if (np->rxopt.bits.rxhlim) {
- int hlim = np->mcast_hops;
+ int hlim = READ_ONCE(np->mcast_hops);
+
put_cmsg(&msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
}
if (np->rxopt.bits.rxtclass) {
@@ -1197,7 +1198,8 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
put_cmsg(&msg, SOL_IPV6, IPV6_2292PKTINFO, sizeof(src_info), &src_info);
}
if (np->rxopt.bits.rxohlim) {
- int hlim = np->mcast_hops;
+ int hlim = READ_ONCE(np->mcast_hops);
+
put_cmsg(&msg, SOL_IPV6, IPV6_2292HOPLIMIT, sizeof(hlim), &hlim);
}
if (np->rxopt.bits.rxflow) {
@@ -1349,7 +1351,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
if (optname == IPV6_UNICAST_HOPS)
val = READ_ONCE(np->hop_limit);
else
- val = np->mcast_hops;
+ val = READ_ONCE(np->mcast_hops);
if (val < 0) {
rcu_read_lock();
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3a88545a265d..54db5fab318b 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1542,7 +1542,8 @@ ipv6_pktoptions:
if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo)
np->mcast_oif = tcp_v6_iif(opt_skb);
if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
- np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit;
+ WRITE_ONCE(np->mcast_hops,
+ ipv6_hdr(opt_skb)->hop_limit);
if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass)
np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb));
if (np->repflow)