Subject: Re: [PATCH linux v2 net-next 2/4] bonding: Allow userspace to set actors' macaddr in an AD-system.

From: Jonathan Toppins <[email-masked]>
Date: Fri, 08 May 2015 13:14:55 -0400

On 5/8/15 1:03 PM, Nikolay Aleksandrov wrote:
> On 05/08/2015 06:45 PM, Jonathan Toppins wrote:
>> On 5/8/15 10:12 AM, Nikolay Aleksandrov wrote:
>>> On 05/08/2015 11:09 AM, Nikolay Aleksandrov wrote:
>>>> On 05/06/2015 10:41 PM, Jonathan Toppins wrote:
>>>>> From: Mahesh Bandewar <[email-masked]>
>>>>>
>>>>> In an AD system, the communication between actor and partner is the
>>>>> business between these two entities. In the current setup anyone on the
>>>>> same L2 can "guess" the LACPDU contents and then possibly send the
>>>>> spoofed LACPDUs and trick the partner causing connectivity issues for
>>>>> the AD system. This patch allows to use a random mac-address obscuring
>>>>> it's identity making it harder for someone in the L2 is do the same thing.
>>>>>
>>>>> This patch allows user-space to choose the mac-address for the AD-system.
>>>>> This mac-address can not be NULL or a Multicast. If the mac-address is set
>>>>> from user-space; kernel will honor it and will not overwrite it. In the
>>>>> absence (value from user space); the logic will default to using the
>>>>> masters' mac as the mac-address for the AD-system.
>>>>>
>>>>> It can be set using example code below -
>>>>>
>>>>>      # modprobe bonding mode=4
>>>>>      # sys_mac_addr=$(printf '%02x:%02x:%02x:%02x:%02x:%02x' \
>>>>>                       $(( (RANDOM & 0xFE) | 0x02 )) \
>>>>>                       $(( RANDOM & 0xFF )) \
>>>>>                       $(( RANDOM & 0xFF )) \
>>>>>                       $(( RANDOM & 0xFF )) \
>>>>>                       $(( RANDOM & 0xFF )) \
>>>>>                       $(( RANDOM & 0xFF )))
>>>>>      # echo $sys_mac_addr > /sys/class/net/bond0/bonding/ad_actor_system
>>>>>      # echo +eth1 > /sys/class/net/bond0/bonding/slaves
>>>>>      ...
>>>>>      # ip link set bond0 up
>>>>>
>>>>> Signed-off-by: Mahesh Bandewar <[email-masked]>
>>>>> Reviewed-by: Nikolay Aleksandrov <[email-masked]>
>>>>> [jt: fixed up style issues reported by checkpatch, also changed
>>>>>     bond_option_ad_actor_system_set to assume a binary mac so it can
>>>>>     be reused in the netlink option set case]
>>>>> Signed-off-by: Jonathan Toppins <[email-masked]>
>>>>> ---
>>>>> v2:
>>>>>     * rebased
>>>>>
>>>>>    Documentation/networking/bonding.txt |   12 +++++++++++
>>>>>    drivers/net/bonding/bond_3ad.c       |    7 +++++-
>>>>>    drivers/net/bonding/bond_main.c      |    1 +
>>>>>    drivers/net/bonding/bond_options.c   |   21 ++++++++++++++++++
>>>>>    drivers/net/bonding/bond_procfs.c    |    6 ++++++
>>>>>    drivers/net/bonding/bond_sysfs.c     |   39
>>>>> ++++++++++++++++++++++++++++++++++
>>>>>    include/net/bond_options.h           |    1 +
>>>>>    include/net/bonding.h                |    1 +
>>>>>    8 files changed, 87 insertions(+), 1 deletion(-)
>>>>>
>>>> <<<snip>>>
>>>>>    /* Searches for an option by name */
>>>>> @@ -1375,3 +1384,15 @@ static int
>>>>> bond_option_ad_actor_sys_prio_set(struct bonding *bond,
>>>>>        bond->params.ad_actor_sys_prio = newval->value;
>>>>>        return 0;
>>>>>    }
>>>>> +
>>>>> +static int bond_option_ad_actor_system_set(struct bonding *bond,
>>>>> +                       const struct bond_opt_value *newval)
>>>>> +{
>>>>> +    if (!is_valid_ether_addr(newval->string)) {
>>>>> +        netdev_err(bond->dev, "Invalid MAC address.\n");
>>>>> +        return -EINVAL;
>>>>> +    }
>>>>> +
>>>>> +    ether_addr_copy(bond->params.ad_actor_system, newval->string);
>>>>> +    return 0;
>>>>> +}
>>>>> diff --git a/drivers/net/bonding/bond_procfs.c
>>>>> b/drivers/net/bonding/bond_procfs.c
>>>>> index 1136929..e7f3047 100644
>>>>> --- a/drivers/net/bonding/bond_procfs.c
>>>>> +++ b/drivers/net/bonding/bond_procfs.c
>>>>> @@ -137,6 +137,8 @@ static void bond_info_show_master(struct seq_file
>>>>> *seq)
>>>>>                   optval->string);
>>>>>            seq_printf(seq, "System priority: %d\n",
>>>>>                   BOND_AD_INFO(bond).system.sys_priority);
>>>>> +        seq_printf(seq, "System MAC address: %pM\n",
>>>>> +               &BOND_AD_INFO(bond).system.sys_mac_addr);
>>>>>
>>>>>            if (__bond_3ad_get_active_agg_info(bond, &ad_info)) {
>>>>>                seq_printf(seq, "bond %s has no active aggregator\n",
>>>>> @@ -200,6 +202,8 @@ static void bond_info_show_slave(struct seq_file *seq,
>>>>>                seq_puts(seq, "details actor lacp pdu:\n");
>>>>>                seq_printf(seq, "    system priority: %d\n",
>>>>>                       port->actor_system_priority);
>>>>> +            seq_printf(seq, "    system mac address: %pM\n",
>>>>> +                   &port->actor_system);
>>>>>                seq_printf(seq, "    port key: %d\n",
>>>>>                       port->actor_oper_port_key);
>>>>>                seq_printf(seq, "    port priority: %d\n",
>>>>> @@ -212,6 +216,8 @@ static void bond_info_show_slave(struct seq_file *seq,
>>>>>                seq_puts(seq, "details partner lacp pdu:\n");
>>>>>                seq_printf(seq, "    system priority: %d\n",
>>>>>                       port->partner_oper.system_priority);
>>>>> +            seq_printf(seq, "    system mac address: %pM\n",
>>>>> +                   &port->partner_oper.system);
>>>>>                seq_printf(seq, "    oper key: %d\n",
>>>>>                       port->partner_oper.key);
>>>>>                seq_printf(seq, "    port priority: %d\n",
>>>>> diff --git a/drivers/net/bonding/bond_sysfs.c
>>>>> b/drivers/net/bonding/bond_sysfs.c
>>>>> index 4a76266..5e4c2ea 100644
>>>>> --- a/drivers/net/bonding/bond_sysfs.c
>>>>> +++ b/drivers/net/bonding/bond_sysfs.c
>>>>> @@ -706,6 +706,44 @@ static ssize_t
>>>>> bonding_show_ad_actor_sys_prio(struct device *d,
>>>>>    static DEVICE_ATTR(ad_actor_sys_prio, S_IRUGO | S_IWUSR,
>>>>>               bonding_show_ad_actor_sys_prio, bonding_sysfs_store_option);
>>>>>
>>>>> +static ssize_t bonding_show_ad_actor_system(struct device *d,
>>>>> +                        struct device_attribute *attr,
>>>>> +                        char *buf)
>>>>> +{
>>>>> +    struct bonding *bond = to_bond(d);
>>>>> +
>>>>> +    if (BOND_MODE(bond) == BOND_MODE_8023AD)
>>>>> +        return sprintf(buf, "%pM\n", bond->params.ad_actor_system);
>>>>> +
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>> +static ssize_t bonding_store_ad_actor_system(struct device *d,
>>>>> +                         struct device_attribute *attr,
>>>>> +                         const char *buffer, size_t count)
>>>>> +{
>>>>> +    struct bonding *bond = to_bond(d);
>>>>> +    u8 macaddr[ETH_ALEN];
>>>>> +    int ret;
>>>>> +
>>>>> +    ret = sscanf(buffer, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
>>>>> +             &macaddr[0], &macaddr[1], &macaddr[2],
>>>>> +             &macaddr[3], &macaddr[4], &macaddr[5]);
>>>>> +    if (ret != ETH_ALEN) {
>>>>> +        netdev_err(bond->dev, "Invalid MAC address.\n");
>>>>> +        return -EINVAL;
>>>>> +    }
>>>>> +
>>>>> +    ret = bond_opt_tryset_rtnl(bond, BOND_OPT_AD_ACTOR_SYSTEM, macaddr);
>>>>> +    if (!ret)
>>>>> +        ret = count;
>>>>> +
>>>>> +    return ret;
>>>>> +}
>>>>> +
>>>>> +static DEVICE_ATTR(ad_actor_system, S_IRUGO | S_IWUSR,
>>>>> +           bonding_show_ad_actor_system, bonding_store_ad_actor_system);
>>>>> +
>>>> Hi,
>>>> I must've missed this part the first time around. Could you please explain
>>>> why can't you do all the checks from the set function and you need a
>>>> special sysfs set one for this option here ?
>>>> The generic bonding sysfs set function was introduced in order to remove
>>>> these and make use of the new option API, and this looks like a step
>>>> backwards.
>>>>
>>>> Nik
>>>>
>>> If you did this to re-use the set function in the netlink code, you can
>>> take a look at how arp_ip_targets is handled (same issue) and do something
>>> similar.
>>
>> True arp_ip_targets does do something similar, it can use the string to
>> represent the string of the IPv4 address and then a u32 to represent the
>> binary version. That appears to be how it differentiates. Unless I stuff
>> the MAC inside the u64 value I could not take advantage in the same way. If
>> it seems acceptable to do this I can try that.
>>
> I realize it won't be pretty, but this is currently the only option that
> needs such workaround. I think we can later change the value storage to be
> a union so it will be easier to use as needed.
> It'd be nice to have some more opinions on this, but the general direction
> has been (and still is afaik) to remove the per-option sysfs functions and
> to reduce code duplication, for reference see commit dc3e5d18f2a2
> ("bonding: make a generic sysfs option store and fix comments").
> So I think the extra-work is worth it.

Thanks for the input. Will work on changing it to stuff the binary 
version of the MAC into the u64 and move back the scanf call into the 
option specific set. Agree on the general principle of increasing code 
reuse.

Maybe changing bond_opt_value to something like:

struct bond_opt_value {
	void *data;
	int dlen;
	int type;
};

Obviously with some unions thrown in there so we don't have to rewrite 
every set function.

>
> Cheers,
>   Nik
>
>>>
>>>
>>>>>    static struct attribute *per_bond_attrs[] = {
>>>>>        &dev_attr_slaves.attr,
>>>>>        &dev_attr_mode.attr,
>>>>> @@ -740,6 +778,7 @@ static struct attribute *per_bond_attrs[] = {
>>>>>        &dev_attr_packets_per_slave.attr,
>>>>>        &dev_attr_tlb_dynamic_lb.attr,
>>>>>        &dev_attr_ad_actor_sys_prio.attr,
>>>>> +    &dev_attr_ad_actor_system.attr,
>>>>>        NULL,
>>>>>    };
>>>>>
>>>>> diff --git a/include/net/bond_options.h b/include/net/bond_options.h
>>>>> index 894002a..eeeefa1 100644
>>>>> --- a/include/net/bond_options.h
>>>>> +++ b/include/net/bond_options.h
>>>>> @@ -64,6 +64,7 @@ enum {
>>>>>        BOND_OPT_SLAVES,
>>>>>        BOND_OPT_TLB_DYNAMIC_LB,
>>>>>        BOND_OPT_AD_ACTOR_SYS_PRIO,
>>>>> +    BOND_OPT_AD_ACTOR_SYSTEM,
>>>>>        BOND_OPT_LAST
>>>>>    };
>>>>>
>>>>> diff --git a/include/net/bonding.h b/include/net/bonding.h
>>>>> index 405cf87..650f386 100644
>>>>> --- a/include/net/bonding.h
>>>>> +++ b/include/net/bonding.h
>>>>> @@ -137,6 +137,7 @@ struct bond_params {
>>>>>        int tlb_dynamic_lb;
>>>>>        struct reciprocal_value reciprocal_packets_per_slave;
>>>>>        u16 ad_actor_sys_prio;
>>>>> +    u8 ad_actor_system[ETH_ALEN];
>>>>>    };
>>>>>
>>>>>    struct bond_parm_tbl {
>>>>>
>>>>
>>>
>>
>