net: fib_rules: Convert RTM_DELRULE to per-netns RTNL.

fib_nl_delrule() is the doit() handler for RTM_DELRULE but also called
from vrf_newlink() in case something fails in vrf_add_fib_rules().

In the latter case, RTNL is already held and the 4th arg is true.

Let's hold per-netns RTNL in fib_delrule() if rtnl_held is false.

Now we can place ASSERT_RTNL_NET() in call_fib_rule_notifiers().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20250207072502.87775-9-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 10a7336b8d44f165df226bebb3ce2d03d9354deb..5045affeac78df69ba71c34e9c4561f74b66a504 100644 (file)
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -371,7 +371,8 @@ static int call_fib_rule_notifiers(struct net *net,
                .rule = rule,
        };
 
-       ASSERT_RTNL();
+       ASSERT_RTNL_NET(net);
+
        /* Paired with READ_ONCE() in fib_rules_seq() */
        WRITE_ONCE(ops->fib_rules_seq, ops->fib_rules_seq + 1);
        return call_fib_notifiers(net, event_type, &info.info);
@@ -944,6 +945,9 @@ int fib_delrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,
        if (err)
                goto errout;
 
+       if (!rtnl_held)
+               rtnl_net_lock(net);
+
        err = fib_nl2rule_rtnl(nlrule, ops, tb, extack);
        if (err)
                goto errout_free;
@@ -998,10 +1002,12 @@ int fib_delrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,
                }
        }
 
-       call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule, ops,
-                               NULL);
-       notify_rule_change(RTM_DELRULE, rule, ops, nlh,
-                          NETLINK_CB(skb).portid);
+       call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule, ops, NULL);
+
+       if (!rtnl_held)
+               rtnl_net_unlock(net);
+
+       notify_rule_change(RTM_DELRULE, rule, ops, nlh, NETLINK_CB(skb).portid);
        fib_rule_put(rule);
        flush_route_cache(ops);
        rules_ops_put(ops);
@@ -1009,6 +1015,8 @@ int fib_delrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,
        return 0;
 
 errout_free:
+       if (!rtnl_held)
+               rtnl_net_unlock(net);
        kfree(nlrule);
 errout:
        rules_ops_put(ops);
@@ -1019,7 +1027,7 @@ EXPORT_SYMBOL_GPL(fib_delrule);
 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
                          struct netlink_ext_ack *extack)
 {
-       return fib_delrule(sock_net(skb->sk), skb, nlh, extack, true);
+       return fib_delrule(sock_net(skb->sk), skb, nlh, extack, false);
 }
 
 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
@@ -1334,7 +1342,8 @@ static struct pernet_operations fib_rules_net_ops = {
 static const struct rtnl_msg_handler fib_rules_rtnl_msg_handlers[] __initconst = {
        {.msgtype = RTM_NEWRULE, .doit = fib_nl_newrule,
         .flags = RTNL_FLAG_DOIT_PERNET},
-       {.msgtype = RTM_DELRULE, .doit = fib_nl_delrule},
+       {.msgtype = RTM_DELRULE, .doit = fib_nl_delrule,
+        .flags = RTNL_FLAG_DOIT_PERNET},
        {.msgtype = RTM_GETRULE, .dumpit = fib_nl_dumprule,
         .flags = RTNL_FLAG_DUMP_UNLOCKED},
 };