diff mbox

[maint,4/4] batman-adv: detect local excess vlans in TT request

Message ID 1440170118-10876-5-git-send-email-sw@simonwunderlich.de (mailing list archive)
State Superseded, archived
Headers

Commit Message

Simon Wunderlich Aug. 21, 2015, 3:15 p.m. UTC 
  If the local representation of the global TT table of one originator has
more VLAN entries than the respective TT update, there is some
inconsistency present. By detecting and reporting this inconsistency,
the global table gets updated and the excess VLAN will get removed in
the process.

Reported-by: Alessandro Bolletta <alessandro@mediaspot.net>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/translation-table.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

Comments

Antonio Quartulli Aug. 25, 2015, 9:59 a.m. UTC | #1 
On 21/08/15 17:15, Simon Wunderlich wrote:
> If the local representation of the global TT table of one originator has
> more VLAN entries than the respective TT update, there is some
> inconsistency present. By detecting and reporting this inconsistency,
> the global table gets updated and the excess VLAN will get removed in
> the process.
> 
> Reported-by: Alessandro Bolletta <alessandro@mediaspot.net>
> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
> ---
>  net/batman-adv/translation-table.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
> index dced2da..1adb72e 100644
> --- a/net/batman-adv/translation-table.c
> +++ b/net/batman-adv/translation-table.c
> @@ -2392,6 +2392,7 @@ static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
>  	struct batadv_tvlv_tt_vlan_data *tt_vlan_tmp;
>  	struct batadv_orig_node_vlan *vlan;
>  	uint32_t crc;
> +	bool found;
>  	int i;
>  
>  	/* check if each received CRC matches the locally stored one */
> @@ -2418,6 +2419,26 @@ static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
>  			return false;
>  	}
>  
> +	/* check if any excess VLANs exist locally for the originator
> +	 * which are not mentioned in the TVLV from the originator.
> +	 */
> +	rcu_read_lock();
> +	list_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {
> +		found = false;
> +
> +		for (i = 0; i < num_vlan; i++) {
> +			tt_vlan_tmp = tt_vlan + i;
> +			if (ntohs(tt_vlan_tmp->vid) == vlan->vid) {
> +				found = true;
> +				break;
> +			}
> +		}
> +
> +		if (!found)
> +			return false;
> +	}
> +	rcu_read_unlock();
> +

NAK.

we already do this check slightly above in this function with the
following code:

2426                 vlan = batadv_orig_node_vlan_get(orig_node,
2427
ntohs(tt_vlan_tmp->vid));
2428                 if (!vlan)
2429                         return false;

batadv_orig_node_vlan_get() returns NULL if we don't know this VLAN for
that Originator, therefore the CRC check fails here.


Cheers,

>  	return true;
>  }
>  
>
Simon Wunderlich Aug. 25, 2015, 3:31 p.m. UTC | #2 
On Tuesday 25 August 2015 11:59:01 Antonio Quartulli wrote:
> On 21/08/15 17:15, Simon Wunderlich wrote:
> > If the local representation of the global TT table of one originator has
> > more VLAN entries than the respective TT update, there is some
> > inconsistency present. By detecting and reporting this inconsistency,
> > the global table gets updated and the excess VLAN will get removed in
> > the process.
> > 
> > Reported-by: Alessandro Bolletta <alessandro@mediaspot.net>
> > Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
> > ---
> > 
> >  net/batman-adv/translation-table.c | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/net/batman-adv/translation-table.c
> > b/net/batman-adv/translation-table.c index dced2da..1adb72e 100644
> > --- a/net/batman-adv/translation-table.c
> > +++ b/net/batman-adv/translation-table.c
> > @@ -2392,6 +2392,7 @@ static bool batadv_tt_global_check_crc(struct
> > batadv_orig_node *orig_node,> 
> >  	struct batadv_tvlv_tt_vlan_data *tt_vlan_tmp;
> >  	struct batadv_orig_node_vlan *vlan;
> >  	uint32_t crc;
> > 
> > +	bool found;
> > 
> >  	int i;
> >  	
> >  	/* check if each received CRC matches the locally stored one */
> > 
> > @@ -2418,6 +2419,26 @@ static bool batadv_tt_global_check_crc(struct
> > batadv_orig_node *orig_node,> 
> >  			return false;
> >  	
> >  	}
> > 
> > +	/* check if any excess VLANs exist locally for the originator
> > +	 * which are not mentioned in the TVLV from the originator.
> > +	 */
> > +	rcu_read_lock();
> > +	list_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {
> > +		found = false;
> > +
> > +		for (i = 0; i < num_vlan; i++) {
> > +			tt_vlan_tmp = tt_vlan + i;
> > +			if (ntohs(tt_vlan_tmp->vid) == vlan->vid) {
> > +				found = true;
> > +				break;
> > +			}
> > +		}
> > +
> > +		if (!found)
> > +			return false;
> > +	}
> > +	rcu_read_unlock();
> > +
> 
> NAK.
> 
> we already do this check slightly above in this function with the
> following code:
> 
> 2426                 vlan = batadv_orig_node_vlan_get(orig_node,
> 2427
> ntohs(tt_vlan_tmp->vid));
> 2428                 if (!vlan)
> 2429                         return false;
> 
> batadv_orig_node_vlan_get() returns NULL if we don't know this VLAN for
> that Originator, therefore the CRC check fails here.

That's right, however it only sweeps through the VLANs announced within the 
TT-TVLV. However, my addition tries to check if there are any excess VLAN 
locally which are NOT in that TT-TVLV. I think this patch doesn't take care of 
that, or am I missing something?

For example, think of having VLAN 6 locally with a couple of global entries at 
the originator, but the TT-TVLV only announces VLANs 3,4,5. Then the fact that 
we also have VLAN 6 is not detected, and these (probably wrong) entries are 
never cleaned up.

Thanks!
    Simon
Antonio Quartulli Aug. 25, 2015, 6:28 p.m. UTC | #3 
On 25/08/15 17:31, Simon Wunderlich wrote:
>> batadv_orig_node_vlan_get() returns NULL if we don't know this VLAN for
>> that Originator, therefore the CRC check fails here.
> 
> That's right, however it only sweeps through the VLANs announced within the 
> TT-TVLV. However, my addition tries to check if there are any excess VLAN 
> locally which are NOT in that TT-TVLV. I think this patch doesn't take care of 
> that, or am I missing something?
> 
> For example, think of having VLAN 6 locally with a couple of global entries at 
> the originator, but the TT-TVLV only announces VLANs 3,4,5. Then the fact that 
> we also have VLAN 6 is not detected, and these (probably wrong) entries are 
> never cleaned up.

Right, this check is required, but what about just checking the VLAN
count in the tt packet and in the originator struct ? if the number is
different it means that there must be an excess in the local struct.

Cheers,
Simon Wunderlich Aug. 25, 2015, 9:12 p.m. UTC | #4 
On Tuesday 25 August 2015 20:28:48 Antonio Quartulli wrote:
> On 25/08/15 17:31, Simon Wunderlich wrote:
> >> batadv_orig_node_vlan_get() returns NULL if we don't know this VLAN for
> >> that Originator, therefore the CRC check fails here.
> > 
> > That's right, however it only sweeps through the VLANs announced within
> > the
> > TT-TVLV. However, my addition tries to check if there are any excess VLAN
> > locally which are NOT in that TT-TVLV. I think this patch doesn't take
> > care of that, or am I missing something?
> > 
> > For example, think of having VLAN 6 locally with a couple of global
> > entries at the originator, but the TT-TVLV only announces VLANs 3,4,5.
> > Then the fact that we also have VLAN 6 is not detected, and these
> > (probably wrong) entries are never cleaned up.
> 
> Right, this check is required, but what about just checking the VLAN
> count in the tt packet and in the originator struct ? if the number is
> different it means that there must be an excess in the local struct.

You are right, just counting would be way simpler than comparing for the right 
VLANs (since we don't use that information anyway). And this patch also did 
not unlock the rcu-lock properly ... I'll resend this one with the simpler 
method.

Thanks!
    Simon
diff mbox

Patch

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index dced2da..1adb72e 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -2392,6 +2392,7 @@  static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
 	struct batadv_tvlv_tt_vlan_data *tt_vlan_tmp;
 	struct batadv_orig_node_vlan *vlan;
 	uint32_t crc;
+	bool found;
 	int i;
 
 	/* check if each received CRC matches the locally stored one */
@@ -2418,6 +2419,26 @@  static bool batadv_tt_global_check_crc(struct batadv_orig_node *orig_node,
 			return false;
 	}
 
+	/* check if any excess VLANs exist locally for the originator
+	 * which are not mentioned in the TVLV from the originator.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {
+		found = false;
+
+		for (i = 0; i < num_vlan; i++) {
+			tt_vlan_tmp = tt_vlan + i;
+			if (ntohs(tt_vlan_tmp->vid) == vlan->vid) {
+				found = true;
+				break;
+			}
+		}
+
+		if (!found)
+			return false;
+	}
+	rcu_read_unlock();
+
 	return true;
 }