[PATCH net-next 1/5] rtnetlink: provide permanent hardware address in RTM_NEWLINK

Michal Kubecek
2019-12-09T19:55:29Z

Permanent hardware address of a network device was traditionally provided
via ethtool ioctl interface but as Jiri Pirko pointed out in a review of
ethtool netlink interface, rtnetlink is much more suitable for it so let's
add it to the RTM_NEWLINK message.

Add IFLA_PERM_ADDRESS attribute to RTM_NEWLINK messages unless the
permanent address is all zeros (i.e. device driver did not fill it). As
permanent address is not modifiable, reject userspace requests containing
IFLA_PERM_ADDRESS attribute.

Note: we already provide permanent hardware address for bond slaves;
unfortunately we cannot drop that attribute for backward compatibility
reasons.

v5 -> v6: only add the attribute if permanent address is not zero

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
---
include/uapi/linux/if_link.h | 1 +
net/core/rtnetlink.c | 5 +++++
2 files changed, 6 insertions(+)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 8aec8769d944..1d69f637c5d6 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -169,6 +169,7 @@ enum {
IFLA_MAX_MTU,
IFLA_PROP_LIST,
IFLA_ALT_IFNAME, /* Alternative ifname */
+ IFLA_PERM_ADDRESS,
__IFLA_MAX
};

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 02916f43bf63..20bc406f3871 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1041,6 +1041,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
+ nla_total_size(4) /* IFLA_MIN_MTU */
+ nla_total_size(4) /* IFLA_MAX_MTU */
+ rtnl_prop_list_size(dev)
+ + nla_total_size(MAX_ADDR_LEN) /* IFLA_PERM_ADDRESS */
+ 0;
}

@@ -1757,6 +1758,9 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
nla_put_s32(skb, IFLA_NEW_IFINDEX, new_ifindex) < 0)
goto nla_put_failure;

+ if (memchr_inv(dev->perm_addr, '\0', dev->addr_len) &&
+ nla_put(skb, IFLA_PERM_ADDRESS, dev->addr_len, dev->perm_addr))
+ goto nla_put_failure;

rcu_read_lock();
if (rtnl_fill_link_af(skb, dev, ext_filter_mask))
@@ -1822,6 +1826,7 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
[IFLA_PROP_LIST] = { .type = NLA_NESTED },
[IFLA_ALT_IFNAME] = { .type = NLA_STRING,
.len = ALTIFNAMSIZ - 1 },
+ [IFLA_PERM_ADDRESS] = { .type = NLA_REJECT },
};

static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
--
2.24.0