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Message-ID: <8635jp23ez.fsf@gmail.com>
Date: Thu, 10 Mar 2022 17:11:32 +0100
From: Hans Schultz <schultz.hans@...il.com>
To: Nikolay Aleksandrov <razor@...ckwall.org>,
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 tor, mar 10, 2022 at 17:57, Nikolay Aleksandrov <razor@...ckwall.org> wrote:
> 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.
Ahh yes, NDA_FLAGS_EXT was not there in the 5.15.x kernel I have
originally being making the patches in.
I hope that the handling of nested attributes has been fixed in
iproute2. ;-)
>
> 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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