From: David Ahern dsahern@gmail.com
[ Upstream commit 77d5bc7e6a6cf8bbeca31aab7f0c5449a5eee762 ]
Julian noted that rt_uses_gateway has a more subtle use than 'is gateway set': https://lore.kernel.org/netdev/alpine.LFD.2.21.1909151104060.2546@ja.home.ss...
Revert that part of the commit referenced in the Fixes tag.
Currently, there are no u8 holes in 'struct rtable'. There is a 4-byte hole in the second cacheline which contains the gateway declaration. So move rt_gw_family down to the gateway declarations since they are always used together, and then re-use that u8 for rt_uses_gateway. End result is that rtable size is unchanged.
Fixes: 1550c171935d ("ipv4: Prepare rtable for IPv6 gateway") Reported-by: Julian Anastasov ja@ssi.bg Signed-off-by: David Ahern dsahern@gmail.com Reviewed-by: Julian Anastasov ja@ssi.bg Signed-off-by: Jakub Kicinski jakub.kicinski@netronome.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/infiniband/core/addr.c | 2 +- include/net/route.h | 3 ++- net/ipv4/inet_connection_sock.c | 4 ++-- net/ipv4/ip_forward.c | 2 +- net/ipv4/ip_output.c | 2 +- net/ipv4/route.c | 36 +++++++++++++++++++++--------------- net/ipv4/xfrm4_policy.c | 1 + 7 files changed, 29 insertions(+), 21 deletions(-)
--- a/drivers/infiniband/core/addr.c +++ b/drivers/infiniband/core/addr.c @@ -352,7 +352,7 @@ static bool has_gateway(const struct dst
if (family == AF_INET) { rt = container_of(dst, struct rtable, dst); - return rt->rt_gw_family == AF_INET; + return rt->rt_uses_gateway; }
rt6 = container_of(dst, struct rt6_info, dst); --- a/include/net/route.h +++ b/include/net/route.h @@ -53,10 +53,11 @@ struct rtable { unsigned int rt_flags; __u16 rt_type; __u8 rt_is_input; - u8 rt_gw_family; + __u8 rt_uses_gateway;
int rt_iif;
+ u8 rt_gw_family; /* Info on neighbour */ union { __be32 rt_gw4; --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -560,7 +560,7 @@ struct dst_entry *inet_csk_route_req(con rt = ip_route_output_flow(net, fl4, sk); if (IS_ERR(rt)) goto no_route; - if (opt && opt->opt.is_strictroute && rt->rt_gw_family) + if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) goto route_err; rcu_read_unlock(); return &rt->dst; @@ -598,7 +598,7 @@ struct dst_entry *inet_csk_route_child_s rt = ip_route_output_flow(net, fl4, sk); if (IS_ERR(rt)) goto no_route; - if (opt && opt->opt.is_strictroute && rt->rt_gw_family) + if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) goto route_err; return &rt->dst;
--- a/net/ipv4/ip_forward.c +++ b/net/ipv4/ip_forward.c @@ -123,7 +123,7 @@ int ip_forward(struct sk_buff *skb)
rt = skb_rtable(skb);
- if (opt->is_strictroute && rt->rt_gw_family) + if (opt->is_strictroute && rt->rt_uses_gateway) goto sr_failed;
IPCB(skb)->flags |= IPSKB_FORWARDED; --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -482,7 +482,7 @@ int __ip_queue_xmit(struct sock *sk, str skb_dst_set_noref(skb, &rt->dst);
packet_routed: - if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_gw_family) + if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) goto no_route;
/* OK, we know where to send it, allocate and build IP header. */ --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -634,6 +634,7 @@ static void fill_route_from_fnhe(struct
if (fnhe->fnhe_gw) { rt->rt_flags |= RTCF_REDIRECTED; + rt->rt_uses_gateway = 1; rt->rt_gw_family = AF_INET; rt->rt_gw4 = fnhe->fnhe_gw; } @@ -1312,7 +1313,7 @@ static unsigned int ipv4_mtu(const struc mtu = READ_ONCE(dst->dev->mtu);
if (unlikely(ip_mtu_locked(dst))) { - if (rt->rt_gw_family && mtu > 576) + if (rt->rt_uses_gateway && mtu > 576) mtu = 576; }
@@ -1569,6 +1570,7 @@ static void rt_set_nexthop(struct rtable struct fib_nh_common *nhc = FIB_RES_NHC(*res);
if (nhc->nhc_gw_family && nhc->nhc_scope == RT_SCOPE_LINK) { + rt->rt_uses_gateway = 1; rt->rt_gw_family = nhc->nhc_gw_family; /* only INET and INET6 are supported */ if (likely(nhc->nhc_gw_family == AF_INET)) @@ -1634,6 +1636,7 @@ struct rtable *rt_dst_alloc(struct net_d rt->rt_iif = 0; rt->rt_pmtu = 0; rt->rt_mtu_locked = 0; + rt->rt_uses_gateway = 0; rt->rt_gw_family = 0; rt->rt_gw4 = 0; INIT_LIST_HEAD(&rt->rt_uncached); @@ -2664,6 +2667,7 @@ struct dst_entry *ipv4_blackhole_route(s rt->rt_genid = rt_genid_ipv4(net); rt->rt_flags = ort->rt_flags; rt->rt_type = ort->rt_type; + rt->rt_uses_gateway = ort->rt_uses_gateway; rt->rt_gw_family = ort->rt_gw_family; if (rt->rt_gw_family == AF_INET) rt->rt_gw4 = ort->rt_gw4; @@ -2747,21 +2751,23 @@ static int rt_fill_info(struct net *net, if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr)) goto nla_put_failure; } - if (rt->rt_gw_family == AF_INET && - nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) { - goto nla_put_failure; - } else if (rt->rt_gw_family == AF_INET6) { - int alen = sizeof(struct in6_addr); - struct nlattr *nla; - struct rtvia *via; - - nla = nla_reserve(skb, RTA_VIA, alen + 2); - if (!nla) + if (rt->rt_uses_gateway) { + if (rt->rt_gw_family == AF_INET && + nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) { goto nla_put_failure; - - via = nla_data(nla); - via->rtvia_family = AF_INET6; - memcpy(via->rtvia_addr, &rt->rt_gw6, alen); + } else if (rt->rt_gw_family == AF_INET6) { + int alen = sizeof(struct in6_addr); + struct nlattr *nla; + struct rtvia *via; + + nla = nla_reserve(skb, RTA_VIA, alen + 2); + if (!nla) + goto nla_put_failure; + + via = nla_data(nla); + via->rtvia_family = AF_INET6; + memcpy(via->rtvia_addr, &rt->rt_gw6, alen); + } }
expires = rt->dst.expires; --- a/net/ipv4/xfrm4_policy.c +++ b/net/ipv4/xfrm4_policy.c @@ -85,6 +85,7 @@ static int xfrm4_fill_dst(struct xfrm_ds xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | RTCF_LOCAL); xdst->u.rt.rt_type = rt->rt_type; + xdst->u.rt.rt_uses_gateway = rt->rt_uses_gateway; xdst->u.rt.rt_gw_family = rt->rt_gw_family; if (rt->rt_gw_family == AF_INET) xdst->u.rt.rt_gw4 = rt->rt_gw4;