[DECNET]: Add support for fwmark masks in routing rules

Add support for fwmark masks. For compatibility a mask of 0xFFFFFFFF is used
when a mark value != 0 is sent without a mask.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Steven Whitehouse <steve@chygwyn.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/decnet/dn_rules.c

@@ -47,6 +47,7 @@ struct dn_fib_rule
 	u8			flags;
 #ifdef CONFIG_DECNET_ROUTE_FWMARK
 	u32			fwmark;
+	u32			fwmask;
 #endif
 };
 
@@ -116,6 +117,7 @@ static struct nla_policy dn_fib_rule_policy[FRA_MAX+1] __read_mostly = {
 	[FRA_SRC]	= { .type = NLA_U16 },
 	[FRA_DST]	= { .type = NLA_U16 },
 	[FRA_FWMARK]	= { .type = NLA_U32 },
+	[FRA_FWMASK]	= { .type = NLA_U32 },
 	[FRA_TABLE]     = { .type = NLA_U32 },
 };
 
@@ -130,7 +132,7 @@ static int dn_fib_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 		return 0;
 
 #ifdef CONFIG_DECNET_ROUTE_FWMARK
-	if (r->fwmark && (r->fwmark != fl->fld_fwmark))
+	if ((r->fwmark ^ fl->fld_fwmark) & r->fwmask)
 		return 0;
 #endif
 
@@ -168,8 +170,17 @@ static int dn_fib_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 		r->dst = nla_get_u16(tb[FRA_DST]);
 
 #ifdef CONFIG_DECNET_ROUTE_FWMARK
-	if (tb[FRA_FWMARK])
+	if (tb[FRA_FWMARK]) {
 		r->fwmark = nla_get_u32(tb[FRA_FWMARK]);
+		if (r->fwmark)
+			/* compatibility: if the mark value is non-zero all bits
+			 * are compared unless a mask is explicitly specified.
+			 */
+			r->fwmask = 0xFFFFFFFF;
+	}
+
+	if (tb[FRA_FWMASK])
+		r->fwmask = nla_get_u32(tb[FRA_FWMASK]);
 #endif
 
 	r->src_len = frh->src_len;
@@ -195,6 +206,9 @@ static int dn_fib_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 #ifdef CONFIG_DECNET_ROUTE_FWMARK
 	if (tb[FRA_FWMARK] && (r->fwmark != nla_get_u32(tb[FRA_FWMARK])))
 		return 0;
+
+	if (tb[FRA_FWMASK] && (r->fwmask != nla_get_u32(tb[FRA_FWMASK])))
+		return 0;
 #endif
 
 	if (tb[FRA_SRC] && (r->src != nla_get_u16(tb[FRA_SRC])))
@@ -237,6 +251,8 @@ static int dn_fib_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 #ifdef CONFIG_DECNET_ROUTE_FWMARK
 	if (r->fwmark)
 		NLA_PUT_U32(skb, FRA_FWMARK, r->fwmark);
+	if (r->fwmask || r->fwmark)
+		NLA_PUT_U32(skb, FRA_FWMASK, r->fwmask);
 #endif
 	if (r->dst_len)
 		NLA_PUT_U16(skb, FRA_DST, r->dst);