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Message-ID: <e3f57a64-4823-7cf3-0345-3777c44c2fe4@blackwall.org>
Date: Thu, 10 Mar 2022 17:57:22 +0200
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Hans Schultz <schultz.hans@...il.com>, davem@...emloft.net,
kuba@...nel.org
Cc: netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>,
Florian Fainelli <f.fainelli@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Ivan Vecera <ivecera@...hat.com>,
Roopa Prabhu <roopa@...dia.com>,
Daniel Borkmann <daniel@...earbox.net>,
Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org,
bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 1/3] net: bridge: add fdb flag to extent locked
port feature
On 10/03/2022 17:38, Hans Schultz wrote:
> On tor, mar 10, 2022 at 16:42, Nikolay Aleksandrov <razor@...ckwall.org> wrote:
>> On 10/03/2022 16:23, Hans Schultz wrote:
>>> Add an intermediate state for clients behind a locked port to allow for
>>> possible opening of the port for said clients. This feature corresponds
>>> to the Mac-Auth and MAC Authentication Bypass (MAB) named features. The
>>> latter defined by Cisco.
>>>
>>> Signed-off-by: Hans Schultz <schultz.hans+netdev@...il.com>
>>> ---
>>> include/uapi/linux/neighbour.h | 1 +
>>> net/bridge/br_fdb.c | 6 ++++++
>>> net/bridge/br_input.c | 11 ++++++++++-
>>> net/bridge/br_private.h | 3 ++-
>>> 4 files changed, 19 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
>>> index db05fb55055e..83115a592d58 100644
>>> --- a/include/uapi/linux/neighbour.h
>>> +++ b/include/uapi/linux/neighbour.h
>>> @@ -208,6 +208,7 @@ enum {
>>> NFEA_UNSPEC,
>>> NFEA_ACTIVITY_NOTIFY,
>>> NFEA_DONT_REFRESH,
>>> + NFEA_LOCKED,
>>> __NFEA_MAX
>>> };
>>
>> Hmm, can you use NDA_FLAGS_EXT instead ?
>> That should simplify things and reduce the nl size.
>>
>
> I am using NDA_FDB_EXT_ATTRS. NFEA_LOCKED is just the
> flag as the other flags section is full wrt the normal flags, but maybe it
> doesn't fit in that section?
>
Actually wait a second, this is completely wrong use of NDA_FDB_EXT_ATTRS.
That is a nested attribute, so the code below is wrong. More below..
> I will just note that iproute2 support for parsing nested attributes
> does not work, thus the BR_FDB_NOTIFY section (lines 150-165) are
> obsolete with respect to iproute2 as it is now. I cannot rule out that
> someone has some other tool that can handle this BR_FDB_NOTIFY, but I
> could not make iproute2 as it stands handle nested attributes. And of
> course there is no handling of NDA_FDB_EXT_ATTRS in iproute2 now.
> >>> #define NFEA_MAX (__NFEA_MAX - 1)
>>> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
>>> index 6ccda68bd473..396dcf3084cf 100644
>>> --- a/net/bridge/br_fdb.c
>>> +++ b/net/bridge/br_fdb.c
>>> @@ -105,6 +105,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
>>> struct nda_cacheinfo ci;
>>> struct nlmsghdr *nlh;
>>> struct ndmsg *ndm;
>>> + u8 ext_flags = 0;
>>>
>>> nlh = nlmsg_put(skb, portid, seq, type, sizeof(*ndm), flags);
>>> if (nlh == NULL)
>>> @@ -125,11 +126,16 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
>>> ndm->ndm_flags |= NTF_EXT_LEARNED;
>>> if (test_bit(BR_FDB_STICKY, &fdb->flags))
>>> ndm->ndm_flags |= NTF_STICKY;
>>> + if (test_bit(BR_FDB_ENTRY_LOCKED, &fdb->flags))
>>> + ext_flags |= 1 << NFEA_LOCKED;
>>>
>>> if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
>>> goto nla_put_failure;
>>> if (nla_put_u32(skb, NDA_MASTER, br->dev->ifindex))
>>> goto nla_put_failure;
>>> + if (nla_put_u8(skb, NDA_FDB_EXT_ATTRS, ext_flags))
>>> + goto nla_put_failure;
>>> +
This is wrong. NDA_FDB_EXT_ATTRS is a nested attribute, you can't use it as a u8.
You need to have this structure:
[ NDA_FDB_EXT_ATTRS ]
` [ NFEA_LOCKED ]
But that's why I asked if you could use the NDA_FLAGS_EXT attribute. You can see
the logic from the neigh code.
Also note that you need to account for the new attribute's size in fdb_nlmsg_size().
>>> ci.ndm_used = jiffies_to_clock_t(now - fdb->used);
>>> ci.ndm_confirmed = 0;
>>> ci.ndm_updated = jiffies_to_clock_t(now - fdb->updated);
>>> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
>>> index e0c13fcc50ed..897908484b18 100644
>>> --- a/net/bridge/br_input.c
>>> +++ b/net/bridge/br_input.c
>>> @@ -75,6 +75,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>>> struct net_bridge_mcast *brmctx;
>>> struct net_bridge_vlan *vlan;
>>> struct net_bridge *br;
>>> + unsigned long flags = 0;
>>
>> Please move this below...
>>
>>> u16 vid = 0;
>>> u8 state;
>>>
>>> @@ -94,8 +95,16 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>>> br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
>>>
>>> if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
>>> - test_bit(BR_FDB_LOCAL, &fdb_src->flags))
>>> + test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
>>> + if (!fdb_src) {
>>
>> ... here where it's only used.
>>
>
> Forgot that one. Shall do!
>
>>> + set_bit(BR_FDB_ENTRY_LOCKED, &flags);
>>> + br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, flags);
>>> + }
>>> goto drop;
>>> + } else {
>>> + if (test_bit(BR_FDB_ENTRY_LOCKED, &fdb_src->flags))
>>> + goto drop;
>>> + }
>>> }
>>>
>>> nbp_switchdev_frame_mark(p, skb);
>>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>>> index 48bc61ebc211..f5a0b68c4857 100644
>>> --- a/net/bridge/br_private.h
>>> +++ b/net/bridge/br_private.h
>>> @@ -248,7 +248,8 @@ enum {
>>> BR_FDB_ADDED_BY_EXT_LEARN,
>>> BR_FDB_OFFLOADED,
>>> BR_FDB_NOTIFY,
>>> - BR_FDB_NOTIFY_INACTIVE
>>> + BR_FDB_NOTIFY_INACTIVE,
>>> + BR_FDB_ENTRY_LOCKED,
>>> };
>>>
>>> struct net_bridge_fdb_key {
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