net: fib_rules: Add new attribute to set protocol

For ages iproute2 has used `struct rtmsg` as the ancillary header for
FIB rules and in the process set the protocol value to RTPROT_BOOT.
Until ca56209a66 ("net: Allow a rule to track originating protocol")
the kernel rules code ignored the protocol value sent from userspace
and always returned 0 in notifications. To avoid incompatibility with
existing iproute2, send the protocol as a new attribute.

Fixes: cac56209a66 ("net: Allow a rule to track originating protocol")
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -1145,6 +1145,7 @@ static inline size_t vrf_fib_rule_nl_size(void)
 	sz  = NLMSG_ALIGN(sizeof(struct fib_rule_hdr));
 	sz += nla_total_size(sizeof(u8));	/* FRA_L3MDEV */
 	sz += nla_total_size(sizeof(u32));	/* FRA_PRIORITY */
+	sz += nla_total_size(sizeof(u8));       /* FRA_PROTOCOL */
 
 	return sz;
 }
@@ -1174,7 +1175,9 @@ static int vrf_fib_rule(const struct net_device *dev, __u8 family, bool add_it)
 	memset(frh, 0, sizeof(*frh));
 	frh->family = family;
 	frh->action = FR_ACT_TO_TBL;
-	frh->proto = RTPROT_KERNEL;
+
+	if (nla_put_u8(skb, FRA_PROTOCOL, RTPROT_KERNEL))
+		goto nla_put_failure;
 
 	if (nla_put_u8(skb, FRA_L3MDEV, 1))
 		goto nla_put_failure;

include/net/fib_rules.h

@@ -109,7 +109,8 @@ struct fib_rule_notifier_info {
 	[FRA_SUPPRESS_IFGROUP] = { .type = NLA_U32 }, \
 	[FRA_GOTO]	= { .type = NLA_U32 }, \
 	[FRA_L3MDEV]	= { .type = NLA_U8 }, \
-	[FRA_UID_RANGE]	= { .len = sizeof(struct fib_rule_uid_range) }
+	[FRA_UID_RANGE]	= { .len = sizeof(struct fib_rule_uid_range) }, \
+	[FRA_PROTOCOL]  = { .type = NLA_U8 }
 
 static inline void fib_rule_get(struct fib_rule *rule)
 {

include/uapi/linux/fib_rules.h

@@ -23,8 +23,8 @@ struct fib_rule_hdr {
 	__u8		tos;
 
 	__u8		table;
-	__u8		proto;
-	__u8		res1;	/* reserved */
+	__u8		res1;   /* reserved */
+	__u8		res2;	/* reserved */
 	__u8		action;
 
 	__u32		flags;
@@ -58,6 +58,7 @@ enum {
 	FRA_PAD,
 	FRA_L3MDEV,	/* iif or oif is l3mdev goto its table */
 	FRA_UID_RANGE,	/* UID range */
+	FRA_PROTOCOL,   /* Originator of the rule */
 	__FRA_MAX
 };
 

net/core/fib_rules.c

@@ -466,11 +466,13 @@ int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	}
 	refcount_set(&rule->refcnt, 1);
 	rule->fr_net = net;
-	rule->proto = frh->proto;
 
 	rule->pref = tb[FRA_PRIORITY] ? nla_get_u32(tb[FRA_PRIORITY])
 	                              : fib_default_rule_pref(ops);
 
+	rule->proto = tb[FRA_PROTOCOL] ?
+		nla_get_u8(tb[FRA_PROTOCOL]) : RTPROT_UNSPEC;
+
 	if (tb[FRA_IIFNAME]) {
 		struct net_device *dev;
 
@@ -666,7 +668,8 @@ int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	}
 
 	list_for_each_entry(rule, &ops->rules_list, list) {
-		if (frh->proto && (frh->proto != rule->proto))
+		if (tb[FRA_PROTOCOL] &&
+		    (rule->proto != nla_get_u8(tb[FRA_PROTOCOL])))
 			continue;
 
 		if (frh->action && (frh->action != rule->action))
@@ -786,7 +789,8 @@ static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 			 + nla_total_size(4) /* FRA_FWMARK */
 			 + nla_total_size(4) /* FRA_FWMASK */
 			 + nla_total_size_64bit(8) /* FRA_TUN_ID */
-			 + nla_total_size(sizeof(struct fib_kuid_range));
+			 + nla_total_size(sizeof(struct fib_kuid_range))
+			 + nla_total_size(1); /* FRA_PROTOCOL */
 
 	if (ops->nlmsg_payload)
 		payload += ops->nlmsg_payload(rule);
@@ -813,9 +817,12 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 	if (nla_put_u32(skb, FRA_SUPPRESS_PREFIXLEN, rule->suppress_prefixlen))
 		goto nla_put_failure;
 	frh->res1 = 0;
+	frh->res2 = 0;
 	frh->action = rule->action;
 	frh->flags = rule->flags;
-	frh->proto = rule->proto;
+
+	if (nla_put_u8(skb, FRA_PROTOCOL, rule->proto))
+		goto nla_put_failure;
 
 	if (rule->action == FR_ACT_GOTO &&
 	    rcu_access_pointer(rule->ctarget) == NULL)