From: David Ahern <dsahern@gmail.com>
Date: Sun, 21 May 2017 10:12:05 -0600
Subject: net: ipv6: Add extack messages for route add failures
Patch-mainline: v4.13-rc1
Git-commit: d5d531cb50a848b9f6767fcd7ef0c7767b3e9b21
References: bsc#1112374

Add messages for non-obvious errors (e.g, no need to add text for malloc
failures or ENODEV failures). This mostly covers the annoying EINVAL errors
Some message strings violate the 80-columns but searchable strings need to
trump that rule.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/ipv6/ip6_fib.c |    4 ++++
 net/ipv6/route.c   |   40 ++++++++++++++++++++++++++++++++--------
 2 files changed, 36 insertions(+), 8 deletions(-)

--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -515,6 +515,8 @@ static struct fib6_node *fib6_add_1(stru
 		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 			if (!allow_create) {
 				if (replace_required) {
+					NL_SET_ERR_MSG(extack,
+						       "Can not replace route - no match found");
 					pr_warn("Can't replace route, no match found\n");
 					return ERR_PTR(-ENOENT);
 				}
@@ -561,6 +563,8 @@ static struct fib6_node *fib6_add_1(stru
 		 * That would keep IPv6 consistent with IPv4
 		 */
 		if (replace_required) {
+			NL_SET_ERR_MSG(extack,
+				       "Can not replace route - no match found");
 			pr_warn("Can't replace route, no match found\n");
 			return ERR_PTR(-ENOENT);
 		}
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1867,14 +1867,25 @@ static struct rt6_info *ip6_route_info_c
 	int err = -EINVAL;
 
 	/* RTF_PCPU is an internal flag; can not be set by userspace */
-	if (cfg->fc_flags & RTF_PCPU)
+	if (cfg->fc_flags & RTF_PCPU) {
+		NL_SET_ERR_MSG(extack, "Userspace can not set RTF_PCPU");
 		goto out;
+	}
 
-	if (cfg->fc_dst_len > 128 || cfg->fc_src_len > 128)
+	if (cfg->fc_dst_len > 128) {
+		NL_SET_ERR_MSG(extack, "Invalid prefix length");
+		goto out;
+	}
+	if (cfg->fc_src_len > 128) {
+		NL_SET_ERR_MSG(extack, "Invalid source address length");
 		goto out;
+	}
 #ifndef CONFIG_IPV6_SUBTREES
-	if (cfg->fc_src_len)
+	if (cfg->fc_src_len) {
+		NL_SET_ERR_MSG(extack,
+			       "Specifying source address requires IPV6_SUBTREES to be enabled");
 		goto out;
+	}
 #endif
 	if (cfg->fc_ifindex) {
 		err = -ENODEV;
@@ -2025,9 +2036,10 @@ static struct rt6_info *ip6_route_info_c
 		err = -EINVAL;
 		if (ipv6_chk_addr_and_flags(net, gw_addr,
 					    gwa_type & IPV6_ADDR_LINKLOCAL ?
-					    dev : NULL, 0, 0))
+					    dev : NULL, 0, 0)) {
+			NL_SET_ERR_MSG(extack, "Invalid gateway address");
 			goto out;
-
+		}
 		rt->rt6i_gateway = *gw_addr;
 
 		if (gwa_type != (IPV6_ADDR_LINKLOCAL|IPV6_ADDR_UNICAST)) {
@@ -2043,8 +2055,11 @@ static struct rt6_info *ip6_route_info_c
 			   addressing
 			 */
 			if (!(gwa_type & (IPV6_ADDR_UNICAST |
-					  IPV6_ADDR_MAPPED)))
+					  IPV6_ADDR_MAPPED))) {
+				NL_SET_ERR_MSG(extack,
+					       "Invalid gateway address");
 				goto out;
+			}
 
 			if (cfg->fc_table) {
 				grt = ip6_nh_lookup_table(net, cfg, gw_addr);
@@ -2084,8 +2099,14 @@ static struct rt6_info *ip6_route_info_c
 				goto out;
 		}
 		err = -EINVAL;
-		if (!dev || (dev->flags & IFF_LOOPBACK))
+		if (!dev) {
+			NL_SET_ERR_MSG(extack, "Egress device not specified");
+			goto out;
+		} else if (dev->flags & IFF_LOOPBACK) {
+			NL_SET_ERR_MSG(extack,
+				       "Egress device can not be loopback device for this route");
 			goto out;
+		}
 	}
 
 	err = -ENODEV;
@@ -2094,6 +2115,7 @@ static struct rt6_info *ip6_route_info_c
 
 	if (!ipv6_addr_any(&cfg->fc_prefsrc)) {
 		if (!ipv6_chk_addr(net, &cfg->fc_prefsrc, dev, 0)) {
+			NL_SET_ERR_MSG(extack, "Invalid source address");
 			err = -EINVAL;
 			goto out;
 		}
@@ -2244,8 +2266,10 @@ static int ip6_route_del(struct fib6_con
 	int err = -ESRCH;
 
 	table = fib6_get_table(cfg->fc_nlinfo.nl_net, cfg->fc_table);
-	if (!table)
+	if (!table) {
+		NL_SET_ERR_MSG(extack, "FIB table does not exist");
 		return err;
+	}
 
 	read_lock_bh(&table->tb6_lock);