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 12:45:09 -0400

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.

>
>
>>>   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 {
>>>
>>
>