From fa17a6d8a5bd0cd7565b613cb804242cd0f6b7ab Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 18 Sep 2023 14:23:21 +0000 Subject: ipv6: lockless IPV6_ADDR_PREFERENCES implementation We have data-races while reading np->srcprefs Switch the field to a plain byte, add READ_ONCE() and WRITE_ONCE() annotations where needed, and IPV6_ADDR_PREFERENCES setsockopt() can now be lockless. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230918142321.1794107-1-edumazet@google.com Signed-off-by: Paolo Abeni --- net/ipv6/ip6_output.c | 2 +- net/ipv6/ipv6_sockglue.c | 19 ++++++++++--------- net/ipv6/route.c | 2 +- 3 files changed, 12 insertions(+), 11 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 7e5d9eeb990f..951ba8089b5b 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1113,7 +1113,7 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk, rcu_read_lock(); from = rt ? rcu_dereference(rt->from) : NULL; err = ip6_route_get_saddr(net, from, &fl6->daddr, - sk ? inet6_sk(sk)->srcprefs : 0, + sk ? READ_ONCE(inet6_sk(sk)->srcprefs) : 0, &fl6->saddr); rcu_read_unlock(); diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index e9dc6f881bb9..7d661735cb9d 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -505,6 +505,10 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname, return -EINVAL; inet6_assign_bit(SNDFLOW, sk, valbool); return 0; + case IPV6_ADDR_PREFERENCES: + if (optlen < sizeof(int)) + return -EINVAL; + return ip6_sock_set_addr_preferences(sk, val); } if (needs_rtnl) rtnl_lock(); @@ -964,11 +968,6 @@ done: retv = xfrm_user_policy(sk, optname, optval, optlen); break; - case IPV6_ADDR_PREFERENCES: - if (optlen < sizeof(int)) - goto e_inval; - retv = __ip6_sock_set_addr_preferences(sk, val); - break; case IPV6_RECVFRAGSIZE: np->rxopt.bits.recvfragsize = valbool; retv = 0; @@ -1415,23 +1414,25 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname, } case IPV6_ADDR_PREFERENCES: + { + u8 srcprefs = READ_ONCE(np->srcprefs); val = 0; - if (np->srcprefs & IPV6_PREFER_SRC_TMP) + if (srcprefs & IPV6_PREFER_SRC_TMP) val |= IPV6_PREFER_SRC_TMP; - else if (np->srcprefs & IPV6_PREFER_SRC_PUBLIC) + else if (srcprefs & IPV6_PREFER_SRC_PUBLIC) val |= IPV6_PREFER_SRC_PUBLIC; else { /* XXX: should we return system default? */ val |= IPV6_PREFER_SRC_PUBTMP_DEFAULT; } - if (np->srcprefs & IPV6_PREFER_SRC_COA) + if (srcprefs & IPV6_PREFER_SRC_COA) val |= IPV6_PREFER_SRC_COA; else val |= IPV6_PREFER_SRC_HOME; break; - + } case IPV6_MINHOPCOUNT: val = READ_ONCE(np->min_hopcount); break; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 9d8dfc7423e4..b132feae3393 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -2622,7 +2622,7 @@ static struct dst_entry *ip6_route_output_flags_noref(struct net *net, if (!any_src) flags |= RT6_LOOKUP_F_HAS_SADDR; else if (sk) - flags |= rt6_srcprefs2flags(inet6_sk(sk)->srcprefs); + flags |= rt6_srcprefs2flags(READ_ONCE(inet6_sk(sk)->srcprefs)); return fib6_rule_lookup(net, fl6, NULL, flags, ip6_pol_route_output); } -- cgit v1.2.3