net: report invalid mtu value via netlink extack

If an invalid MTU value is set through rtnetlink return extra error
information instead of putting message in kernel log. For other cases
where there is no visible API, keep the error report in the log.

Example:
	# ip li set dev enp12s0 mtu 10000
	Error: mtu greater than device maximum.

	# ifconfig enp12s0 mtu 10000
	SIOCSIFMTU: Invalid argument
	# dmesg | tail -1
	[ 2047.795467] enp12s0: mtu greater than device maximum

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c1295c7a452ec482dd31c9bb682da4168747f21d..9c917467a2c75d54b754195fdb2f4f3f207c57ce 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3546,6 +3546,8 @@ int dev_set_alias(struct net_device *, const char *, size_t);
 int dev_get_alias(const struct net_device *, char *, size_t);
 int dev_change_net_namespace(struct net_device *, struct net *, const char *);
 int __dev_set_mtu(struct net_device *, int);
+int dev_set_mtu_ext(struct net_device *dev, int mtu,
+                   struct netlink_ext_ack *extack);
 int dev_set_mtu(struct net_device *, int);
 int dev_change_tx_queue_len(struct net_device *, unsigned long);
 void dev_set_group(struct net_device *, int);

diff --git a/net/core/dev.c b/net/core/dev.c
index 87c42c8249ae443f8bfdfa28eefb16c51ec40d7c..89031b5fef9f720a99ac25cec8010894a5e76d88 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7523,13 +7523,15 @@ int __dev_set_mtu(struct net_device *dev, int new_mtu)
 EXPORT_SYMBOL(__dev_set_mtu);
 
 /**
- *     dev_set_mtu - Change maximum transfer unit
+ *     dev_set_mtu_ext - Change maximum transfer unit
  *     @dev: device
  *     @new_mtu: new transfer unit
+ *     @extack: netlink extended ack
  *
  *     Change the maximum transfer size of the network device.
  */
-int dev_set_mtu(struct net_device *dev, int new_mtu)
+int dev_set_mtu_ext(struct net_device *dev, int new_mtu,
+                   struct netlink_ext_ack *extack)
 {
        int err, orig_mtu;
 
@@ -7538,14 +7540,12 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
 
        /* MTU must be positive, and in range */
        if (new_mtu < 0 || new_mtu < dev->min_mtu) {
-               net_err_ratelimited("%s: Invalid MTU %d requested, hw min %d\n",
-                                   dev->name, new_mtu, dev->min_mtu);
+               NL_SET_ERR_MSG(extack, "mtu less than device minimum");
                return -EINVAL;
        }
 
        if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
-               net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n",
-                                   dev->name, new_mtu, dev->max_mtu);
+               NL_SET_ERR_MSG(extack, "mtu greater than device maximum");
                return -EINVAL;
        }
 
@@ -7573,6 +7573,17 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
        }
        return err;
 }
+
+int dev_set_mtu(struct net_device *dev, int new_mtu)
+{
+       struct netlink_ext_ack extack;
+       int err;
+
+       err = dev_set_mtu_ext(dev, new_mtu, &extack);
+       if (err)
+               net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
+       return err;
+}
 EXPORT_SYMBOL(dev_set_mtu);
 
 /**

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 510d4f765a1346bd97d8e09a6ec413f33a2f38d2..24431e578310cb1602c05ea26a24069d49309c74 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2382,7 +2382,7 @@ static int do_setlink(const struct sk_buff *skb,
        }
 
        if (tb[IFLA_MTU]) {
-               err = dev_set_mtu(dev, nla_get_u32(tb[IFLA_MTU]));
+               err = dev_set_mtu_ext(dev, nla_get_u32(tb[IFLA_MTU]), extack);
                if (err < 0)
                        goto errout;
                status |= DO_SETLINK_MODIFIED;