From 2da23eb07c91241d962f3ff05565065484cd8929 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 12 Sep 2023 16:02:01 +0000 Subject: 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 Reviewed-by: David Ahern Signed-off-by: David S. Miller --- include/linux/ipv6.h | 9 +-------- include/net/ipv6.h | 2 +- net/dccp/ipv6.c | 2 +- net/ipv6/ipv6_sockglue.c | 28 +++++++++++++++------------- net/ipv6/tcp_ipv6.c | 3 ++- net/netfilter/ipvs/ip_vs_sync.c | 2 +- 6 files changed, 21 insertions(+), 25 deletions(-) diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 68cf1ca94914..9cc278b5e4f4 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -214,15 +214,8 @@ struct ipv6_pinfo { __u32 frag_size; s16 hop_limit; + u8 mcast_hops; -#if defined(__BIG_ENDIAN_BITFIELD) - /* Packed in 16bits. */ - __s16 mcast_hops:9; - __u16 __unused_2:7, -#else - __u16 __unused_2:7; - __s16 mcast_hops:9; -#endif int ucast_oif; int mcast_oif; diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 2e8e7e31e02e..8a04a8985336 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -914,7 +914,7 @@ static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6, int hlimit; if (ipv6_addr_is_multicast(&fl6->daddr)) - hlimit = np->mcast_hops; + hlimit = READ_ONCE(np->mcast_hops); else hlimit = READ_ONCE(np->hop_limit); if (hlimit < 0) diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index 33f6ccf6ba77..83617a16b98e 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -676,7 +676,7 @@ ipv6_pktoptions: if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo) np->mcast_oif = inet6_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) 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) diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c index 3c2251cabd04..df1b33b61059 100644 --- a/net/netfilter/ipvs/ip_vs_sync.c +++ b/net/netfilter/ipvs/ip_vs_sync.c @@ -1322,7 +1322,7 @@ static void set_mcast_ttl(struct sock *sk, u_char ttl) struct ipv6_pinfo *np = inet6_sk(sk); /* IPV6_MULTICAST_HOPS */ - np->mcast_hops = ttl; + WRITE_ONCE(np->mcast_hops, ttl); } #endif release_sock(sk); -- cgit v1.2.3