net: fib_rules: Split fib_nl2rule().

We will move RTNL down to fib_nl_newrule() and fib_nl_delrule().

Some operations in fib_nl2rule() require RTNL: fib_default_rule_pref()
and __dev_get_by_name().

Let's split the RTNL parts as fib_nl2rule_rtnl().

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/20250207072502.87775-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 41 insertions, 17 deletions

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 87f731199538..694a8c2884a8 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -550,30 +550,18 @@ static int fib_nl2rule(struct net *net, struct nlmsghdr *nlh,
 	if (tb[FRA_PRIORITY]) {
 		nlrule->pref = nla_get_u32(tb[FRA_PRIORITY]);
 		*user_priority = true;
-	} else {
-		nlrule->pref = fib_default_rule_pref(ops);
 	}
 
 	nlrule->proto = nla_get_u8_default(tb[FRA_PROTOCOL], RTPROT_UNSPEC);
 
 	if (tb[FRA_IIFNAME]) {
-		struct net_device *dev;
-
 		nlrule->iifindex = -1;
 		nla_strscpy(nlrule->iifname, tb[FRA_IIFNAME], IFNAMSIZ);
-		dev = __dev_get_by_name(net, nlrule->iifname);
-		if (dev)
-			nlrule->iifindex = dev->ifindex;
 	}
 
 	if (tb[FRA_OIFNAME]) {
-		struct net_device *dev;
-
 		nlrule->oifindex = -1;
 		nla_strscpy(nlrule->oifname, tb[FRA_OIFNAME], IFNAMSIZ);
-		dev = __dev_get_by_name(net, nlrule->oifname);
-		if (dev)
-			nlrule->oifindex = dev->ifindex;
 	}
 
 	if (tb[FRA_FWMARK]) {
@@ -615,11 +603,6 @@ static int fib_nl2rule(struct net *net, struct nlmsghdr *nlh,
 		}
 
 		nlrule->target = nla_get_u32(tb[FRA_GOTO]);
-		/* Backward jumps are prohibited to avoid endless loops */
-		if (nlrule->target <= nlrule->pref) {
-			NL_SET_ERR_MSG(extack, "Backward goto not supported");
-			goto errout_free;
-		}
 	} else if (nlrule->action == FR_ACT_GOTO) {
 		NL_SET_ERR_MSG(extack, "Missing goto target for action goto");
 		goto errout_free;
@@ -679,6 +662,39 @@ errout:
 	return err;
 }
 
+static int fib_nl2rule_rtnl(struct fib_rule *nlrule,
+			    struct fib_rules_ops *ops,
+			    struct nlattr *tb[],
+			    struct netlink_ext_ack *extack)
+{
+	if (!tb[FRA_PRIORITY])
+		nlrule->pref = fib_default_rule_pref(ops);
+
+	/* Backward jumps are prohibited to avoid endless loops */
+	if (tb[FRA_GOTO] && nlrule->target <= nlrule->pref) {
+		NL_SET_ERR_MSG(extack, "Backward goto not supported");
+		return -EINVAL;
+	}
+
+	if (tb[FRA_IIFNAME]) {
+		struct net_device *dev;
+
+		dev = __dev_get_by_name(nlrule->fr_net, nlrule->iifname);
+		if (dev)
+			nlrule->iifindex = dev->ifindex;
+	}
+
+	if (tb[FRA_OIFNAME]) {
+		struct net_device *dev;
+
+		dev = __dev_get_by_name(nlrule->fr_net, nlrule->oifname);
+		if (dev)
+			nlrule->oifindex = dev->ifindex;
+	}
+
+	return 0;
+}
+
 static int rule_exists(struct fib_rules_ops *ops, struct fib_rule_hdr *frh,
 		       struct nlattr **tb, struct fib_rule *rule)
 {
@@ -801,6 +817,10 @@ int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		goto errout;
 
+	err = fib_nl2rule_rtnl(rule, ops, tb, extack);
+	if (err)
+		goto errout_free;
+
 	if ((nlh->nlmsg_flags & NLM_F_EXCL) &&
 	    rule_exists(ops, frh, tb, rule)) {
 		err = -EEXIST;
@@ -909,6 +929,10 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		goto errout;
 
+	err = fib_nl2rule_rtnl(nlrule, ops, tb, extack);
+	if (err)
+		goto errout;
+
 	rule = rule_find(ops, frh, tb, nlrule, user_priority);
 	if (!rule) {
 		err = -ENOENT;