From beb1afac518dec5a15dc92ba8f0ca016dcf457b4 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 2 Feb 2017 12:37:09 -0800 Subject: [PATCH] net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute IPv6 returns multipath routes as a series of individual routes making their display and handling by userspace different and more complicated than IPv4, putting the burden on the user to see that a route is part of a multipath route and internally creating a multipath route if desired (e.g., libnl does this as of commit 29b71371e764). This patch addresses this difference, allowing multipath routes to be returned using the RTA_MULTIPATH attribute. The end result is that IPv6 multipath routes can be treated and displayed in a format similar to IPv4: $ ip -6 ro ls vrf red 2001:db8:1::/120 dev eth1 proto kernel metric 256 pref medium 2001:db8:2::/120 dev eth2 proto kernel metric 256 pref medium 2001:db8:200::/120 metric 1024 nexthop via 2001:db8:1::2 dev eth1 weight 1 nexthop via 2001:db8:2::2 dev eth2 weight 1 Signed-off-by: David Ahern Signed-off-by: David S. Miller --- net/ipv6/ip6_fib.c | 10 +++++ net/ipv6/route.c | 112 +++++++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 105 insertions(+), 17 deletions(-) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index febde6c112bf..1bf5e22fb95d 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -318,6 +318,16 @@ static int fib6_dump_node(struct fib6_walker *w) w->leaf = rt; return 1; } + + /* Multipath routes are dumped in one route with the + * RTA_MULTIPATH attribute. Jump 'rt' to point to the + * last sibling of this route (no need to dump the + * sibling routes again) + */ + if (rt->rt6i_nsiblings) + rt = list_last_entry(&rt->rt6i_siblings, + struct rt6_info, + rt6i_siblings); } w->leaf = NULL; return 0; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 635b7fdef2eb..c740d9e249a6 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3195,8 +3195,20 @@ static int inet6_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh) return ip6_route_add(&cfg); } -static inline size_t rt6_nlmsg_size(struct rt6_info *rt) +static size_t rt6_nlmsg_size(struct rt6_info *rt) { + int nexthop_len = 0; + + if (rt->rt6i_nsiblings) { + nexthop_len = nla_total_size(0) /* RTA_MULTIPATH */ + + NLA_ALIGN(sizeof(struct rtnexthop)) + + nla_total_size(16) /* RTA_GATEWAY */ + + nla_total_size(4) /* RTA_OIF */ + + lwtunnel_get_encap_size(rt->dst.lwtstate); + + nexthop_len *= rt->rt6i_nsiblings; + } + return NLMSG_ALIGN(sizeof(struct rtmsg)) + nla_total_size(16) /* RTA_SRC */ + nla_total_size(16) /* RTA_DST */ @@ -3210,7 +3222,62 @@ static inline size_t rt6_nlmsg_size(struct rt6_info *rt) + nla_total_size(sizeof(struct rta_cacheinfo)) + nla_total_size(TCP_CA_NAME_MAX) /* RTAX_CC_ALGO */ + nla_total_size(1) /* RTA_PREF */ - + lwtunnel_get_encap_size(rt->dst.lwtstate); + + lwtunnel_get_encap_size(rt->dst.lwtstate) + + nexthop_len; +} + +static int rt6_nexthop_info(struct sk_buff *skb, struct rt6_info *rt, + unsigned int *flags) +{ + if (!netif_running(rt->dst.dev) || !netif_carrier_ok(rt->dst.dev)) { + *flags |= RTNH_F_LINKDOWN; + if (rt->rt6i_idev->cnf.ignore_routes_with_linkdown) + *flags |= RTNH_F_DEAD; + } + + if (rt->rt6i_flags & RTF_GATEWAY) { + if (nla_put_in6_addr(skb, RTA_GATEWAY, &rt->rt6i_gateway) < 0) + goto nla_put_failure; + } + + if (rt->dst.dev && + nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex)) + goto nla_put_failure; + + if (rt->dst.lwtstate && + lwtunnel_fill_encap(skb, rt->dst.lwtstate) < 0) + goto nla_put_failure; + + return 0; + +nla_put_failure: + return -EMSGSIZE; +} + +static int rt6_add_nexthop(struct sk_buff *skb, struct rt6_info *rt) +{ + struct rtnexthop *rtnh; + unsigned int flags = 0; + + rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh)); + if (!rtnh) + goto nla_put_failure; + + rtnh->rtnh_hops = 0; + rtnh->rtnh_ifindex = rt->dst.dev ? rt->dst.dev->ifindex : 0; + + if (rt6_nexthop_info(skb, rt, &flags) < 0) + goto nla_put_failure; + + rtnh->rtnh_flags = flags; + + /* length of rtnetlink header + attributes */ + rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh; + + return 0; + +nla_put_failure: + return -EMSGSIZE; } static int rt6_fill_node(struct net *net, @@ -3264,11 +3331,6 @@ static int rt6_fill_node(struct net *net, else rtm->rtm_type = RTN_UNICAST; rtm->rtm_flags = 0; - if (!netif_running(rt->dst.dev) || !netif_carrier_ok(rt->dst.dev)) { - rtm->rtm_flags |= RTNH_F_LINKDOWN; - if (rt->rt6i_idev->cnf.ignore_routes_with_linkdown) - rtm->rtm_flags |= RTNH_F_DEAD; - } rtm->rtm_scope = RT_SCOPE_UNIVERSE; rtm->rtm_protocol = rt->rt6i_protocol; if (rt->rt6i_flags & RTF_DYNAMIC) @@ -3332,17 +3394,35 @@ static int rt6_fill_node(struct net *net, if (rtnetlink_put_metrics(skb, metrics) < 0) goto nla_put_failure; - if (rt->rt6i_flags & RTF_GATEWAY) { - if (nla_put_in6_addr(skb, RTA_GATEWAY, &rt->rt6i_gateway) < 0) - goto nla_put_failure; - } - - if (rt->dst.dev && - nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex)) - goto nla_put_failure; if (nla_put_u32(skb, RTA_PRIORITY, rt->rt6i_metric)) goto nla_put_failure; + /* For multipath routes, walk the siblings list and add + * each as a nexthop within RTA_MULTIPATH. + */ + if (rt->rt6i_nsiblings) { + struct rt6_info *sibling, *next_sibling; + struct nlattr *mp; + + mp = nla_nest_start(skb, RTA_MULTIPATH); + if (!mp) + goto nla_put_failure; + + if (rt6_add_nexthop(skb, rt) < 0) + goto nla_put_failure; + + list_for_each_entry_safe(sibling, next_sibling, + &rt->rt6i_siblings, rt6i_siblings) { + if (rt6_add_nexthop(skb, sibling) < 0) + goto nla_put_failure; + } + + nla_nest_end(skb, mp); + } else { + if (rt6_nexthop_info(skb, rt, &rtm->rtm_flags) < 0) + goto nla_put_failure; + } + expires = (rt->rt6i_flags & RTF_EXPIRES) ? rt->dst.expires - jiffies : 0; if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0) @@ -3351,8 +3431,6 @@ static int rt6_fill_node(struct net *net, if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt->rt6i_flags))) goto nla_put_failure; - if (lwtunnel_fill_encap(skb, rt->dst.lwtstate) < 0) - goto nla_put_failure; nlmsg_end(skb, nlh); return 0; -- 2.11.0