Messages in this thread | | | Date | Fri, 22 Mar 2019 07:32:08 +0100 | From | Michal Kubecek <> | Subject | Re: [PATCH net-next v4 01/22] rtnetlink: provide permanent hardware address in RTM_NEWLINK |
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On Thu, Mar 21, 2019 at 01:35:05PM -0700, Jakub Kicinski wrote: > On Thu, 21 Mar 2019 14:40:21 +0100 (CET), Michal Kubecek wrote: > > 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. > > > > 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. > > > > Signed-off-by: Michal Kubecek <mkubecek@suse.cz> > > --- > > include/uapi/linux/if_link.h | 1 + > > net/core/rtnetlink.c | 4 ++++ > > 2 files changed, 5 insertions(+) > > > > diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h > > index 5b225ff63b48..351ef746b8b0 100644 > > --- a/include/uapi/linux/if_link.h > > +++ b/include/uapi/linux/if_link.h > > @@ -167,6 +167,7 @@ enum { > > IFLA_NEW_IFINDEX, > > IFLA_MIN_MTU, > > IFLA_MAX_MTU, > > + IFLA_PERM_ADDRESS, > > __IFLA_MAX > > }; > > > > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > > index a51cab95ba64..a72e8f4d777b 100644 > > --- a/net/core/rtnetlink.c > > +++ b/net/core/rtnetlink.c > > @@ -1026,6 +1026,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev, > > + nla_total_size(4) /* IFLA_CARRIER_DOWN_COUNT */ > > + nla_total_size(4) /* IFLA_MIN_MTU */ > > + nla_total_size(4) /* IFLA_MAX_MTU */ > > + + nla_total_size(MAX_ADDR_LEN) /* IFLA_PERM_ADDRESS */ > > + 0; > > } > > > > @@ -1683,6 +1684,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, > > nla_put_s32(skb, IFLA_NEW_IFINDEX, new_ifindex) < 0) > > goto nla_put_failure; > > > > + if (nla_put(skb, IFLA_PERM_ADDRESS, dev->addr_len, dev->perm_addr)) > > Should we check the perm_addr is non-zero, i.e. it has been filled in > by the driver?
It makes sense logically but there is IMHO one practical problem: if we omit the attribute when the address is zero (i.e. not set or maybe a device which does not have permanent address), userspace won't be able to distinguish this case from an older kernel not implementing the attribute.
For the iproute2 patch, I plan to show the permanent address in the output of "ip link show" only if it differs from current address. I think it would be desirable to distinguish "current address is the permanent one" from "no/unknown permanent address" but absence of the attribute could also mean "kernel does not provide the information".
Michal
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