[PATCH net-next 11/19] ipv4: Allow routes to use nexthop objects

[David Ahern]

From: David Ahern <dsah...@gmail.com>

Add support for RTA_NH_ID attribute to allow a user to specify a
nexthop id to use with a route. fc_nh_id is added to fib_config to
hold the value passed in the RTA_NH_ID attribute. If a nexthop id
is given, the gateway, device, encap and multipath attributes can
not be set.

Update fib_nh_match to check ids on a route delete.

Signed-off-by: David Ahern <dsah...@gmail.com>
---
 include/net/ip_fib.h     |  1 +
 net/ipv4/fib_frontend.c  | 19 +++++++++++++++++++
 net/ipv4/fib_semantics.c | 15 +++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 071d280de389..74891397f694 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -44,6 +44,7 @@ struct fib_config {
        u32                     fc_flags;
        u32                     fc_priority;
        __be32                  fc_prefsrc;
+       u32                     fc_nh_id;
        struct nlattr           *fc_mx;
        struct rtnexthop        *fc_mp;
        int                     fc_mx_len;
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 5ea2750982f2..b8cbe50abead 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -675,6 +675,7 @@ const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = {
        [RTA_IP_PROTO]          = { .type = NLA_U8 },
        [RTA_SPORT]             = { .type = NLA_U16 },
        [RTA_DPORT]             = { .type = NLA_U16 },
+       [RTA_NH_ID]             = { .type = NLA_U32 },
 };
 
 int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,
@@ -812,6 +813,18 @@ static int rtm_to_fib_config(struct net *net, struct 
sk_buff *skb,
                        if (err < 0)
                                goto errout;
                        break;
+               case RTA_NH_ID:
+                       cfg->fc_nh_id = nla_get_u32(attr);
+                       break;
+               }
+       }
+
+       if (cfg->fc_nh_id) {
+               if (cfg->fc_oif || cfg->fc_gw_family ||
+                   cfg->fc_encap || cfg->fc_mp) {
+                       NL_SET_ERR_MSG(extack,
+                                      "Nexthop specification and nexthop id 
are mutually exclusive");
+                       return -EINVAL;
                }
        }
 
@@ -838,6 +851,12 @@ static int inet_rtm_delroute(struct sk_buff *skb, struct 
nlmsghdr *nlh,
        if (err < 0)
                goto errout;
 
+       if (cfg.fc_nh_id && !nexthop_find_by_id(net, cfg.fc_nh_id)) {
+               NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
+               err = -EINVAL;
+               goto errout;
+       }
+
        tb = fib_get_table(net, cfg.fc_table);
        if (!tb) {
                NL_SET_ERR_MSG(extack, "FIB table does not exist");
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 01e587a5dcb1..08bbdf3d5173 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -793,6 +793,12 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info 
*fi,
        if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
                return 1;
 
+       if (cfg->fc_nh_id) {
+               if (fi->nh && cfg->fc_nh_id == fi->nh->id)
+                       return 0;
+               return 1;
+       }
+
        if (cfg->fc_oif || cfg->fc_gw_family) {
                struct fib_nh *nh = fib_info_nh(fi, 0);
 
@@ -1306,6 +1312,15 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
                goto err_inval;
        }
 
+       if (cfg->fc_nh_id) {
+               nh = nexthop_find_by_id(net, cfg->fc_nh_id);
+               if (!nh) {
+                       NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
+                       goto err_inval;
+               }
+               nhs = 0;
+       }
+
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
        if (cfg->fc_mp) {
                nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
-- 
2.11.0