IPv4 allows multipath routes to be deleted using just the prefix and
length. For example:
$ ip ro ls vrf red
unreachable default metric 8192
1.1.1.0/24
nexthop via 10.100.1.254 dev eth1 weight 1
nexthop via 10.11.200.2 dev eth11.200 weight 1
10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3
$ ip ro del 1.1.1.0/24 vrf red
$ ip ro ls vrf red
unreachable default metric 8192
10.11.200.0/24 dev eth11.200 proto kernel scope link src 10.11.200.3
10.100.1.0/24 dev eth1 proto kernel scope link src 10.100.1.3
The same notation does not work with IPv6 because of how multipath routes
are implemented for IPv6. For IPv6 only the first nexthop of a multipath
route is deleted if the request contains only a prefix and length. This
leads to unnecessary complexity in userspace dealing with IPv6 multipath
routes.
This patch allows all nexthops to be deleted without specifying each one
in the delete request by passing a new flag, RTM_F_ALL_NEXTHOPS, in
rtm_flags. Internally, this is done by walking the sibling list of the
route matching the specifications given (prefix, length, metric, protocol,
etc).
With this patch (and an updated iproute2 command):
$ ip -6 ro ls vrf red
2001:db8::/120 via 2001:db8:1::62 dev eth1 metric 256 pref medium
2001:db8::/120 via 2001:db8:1::61 dev eth1 metric 256 pref medium
2001:db8::/120 via 2001:db8:1::60 dev eth1 metric 256 pref medium
2001:db8:1::/120 dev eth1 proto kernel metric 256 pref medium
...
$ ip -6 ro del vrf red 1111::1/120
$ ip -6 ro ls vrf red
2001:db8:1::/120 dev eth1 proto kernel metric 256 pref medium
...
The flag is added to fib6_config by converting fc_type to a u16 (as
noted fc_type only uses 8 bits). The new u16 hole is a bitmap with
fc_delete_all_nexthop as the first bit.
Suggested-by: Dinesh Dutt <dd...@cumulusnetworks.com>
Signed-off-by: David Ahern <d...@cumulusnetworks.com>
---
v2
- switched example to rfc 3849 documentation address per request
- changed delete loop to explicitly look at siblings list for
first route matching specs given (metric, protocol, etc)
include/net/ip6_fib.h | 4 +++-
include/uapi/linux/rtnetlink.h | 1 +
net/ipv6/route.c | 28 +++++++++++++++++++++++++---
3 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index a74e2aa40ef4..11ab99e87c5f 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -37,7 +37,9 @@ struct fib6_config {
int fc_ifindex;
u32 fc_flags;
u32 fc_protocol;
- u32 fc_type; /* only 8 bits are used */
+ u16 fc_type; /* only 8 bits are used */
+ u16 fc_delete_all_nexthop : 1,
+ __unused : 15;
struct in6_addr fc_dst;
struct in6_addr fc_src;
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 8c93ad1ef9ab..7fb206bc42f9 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -276,6 +276,7 @@ enum rt_scope_t {
#define RTM_F_EQUALIZE 0x400 /* Multipath equalizer: NI */
#define RTM_F_PREFIX 0x800 /* Prefix addresses */
#define RTM_F_LOOKUP_TABLE 0x1000 /* set rtm_table to FIB lookup result */
+#define RTM_F_ALL_NEXTHOPS 0x2000 /* delete all nexthops (IPv6) */
/* Reserved table identifiers */
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index ce5aaf448c54..c95e2f941468 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2143,6 +2143,26 @@ int ip6_del_rt(struct rt6_info *rt)
return __ip6_del_rt(rt, &info);
}
+/* called with table lock held */
+static int __ip6_route_del(struct rt6_info *rt, struct fib6_config *cfg)
+{
+ int err;
+
+ if (rt->rt6i_nsiblings && cfg->fc_delete_all_nexthop) {
+ struct rt6_info *sibling, *next_sibling;
+
+ list_for_each_entry_safe(sibling, next_sibling,
+ &rt->rt6i_siblings,
+ rt6i_siblings) {
+ err = fib6_del(sibling, &cfg->fc_nlinfo);
+ if (err)
+ return err;
+ }
+ }
+
+ return fib6_del(rt, &cfg->fc_nlinfo);
+}
+
static int ip6_route_del(struct fib6_config *cfg)
{
struct fib6_table *table;
@@ -2176,10 +2196,9 @@ static int ip6_route_del(struct fib6_config *cfg)
continue;
if (cfg->fc_protocol && cfg->fc_protocol !=
rt->rt6i_protocol)
continue;
- dst_hold(&rt->dst);
- read_unlock_bh(&table->tb6_lock);
- return __ip6_del_rt(rt, &cfg->fc_nlinfo);
+ err = __ip6_route_del(rt, cfg);
+ break;
}
}
read_unlock_bh(&table->tb6_lock);
@@ -2849,6 +2868,9 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct
nlmsghdr *nlh,
if (rtm->rtm_flags & RTM_F_CLONED)
cfg->fc_flags |= RTF_CACHE;
+ if (rtm->rtm_flags & RTM_F_ALL_NEXTHOPS)
+ cfg->fc_delete_all_nexthop = 1;
+
cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;
cfg->fc_nlinfo.nlh = nlh;
cfg->fc_nlinfo.nl_net = sock_net(skb->sk);
--
2.1.4
