[PATCH 2/2] mac80211: ignore key index on pairwise key

[PATCH 2/2] mac80211: ignore key index on pairwise key

[Volker Braun]

Our Cisco AP's set key index 3 for the PTK. This patch removes the check
for the key index. I also tried to set idx=0 by hand, but this did not
work (presumably because the AP then discarded my unicast packets with
key index 0 instead of 3).

With these two patches I can successfully use our dynamic wep wireless
network.

Signed-off-by: Volker Braun <volker.braun@physik.hu-berlin.de>


diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index fbdd1d1..66b4f5a 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -385,13 +385,14 @@ static int ieee80211_set_encryption(struct net_device *dev
 
        sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
+       if (idx <0 || idx >= NUM_DEFAULT_KEYS) {
+               printk(KERN_DEBUG "%s: set_encrypt - invalid idx=%d\n",
+                      dev->name, idx);
+               return -EINVAL;
+       }
+
        if (is_broadcast_ether_addr(sta_addr)) {
                sta = NULL;
-               if (idx >= NUM_DEFAULT_KEYS) {
-                       printk(KERN_DEBUG "%s: set_encrypt - invalid idx=%d\n",
-                              dev->name, idx);
-                       return -EINVAL;
-               }
                key = sdata->keys[idx];
 
                /* TODO: consider adding hwaccel support for these; at least
@@ -405,12 +406,6 @@ static int ieee80211_set_encryption(struct net_device *dev,
                 * being, this can be only set at compile time. */
        } else {
                set_tx_key = 0;
-               if (idx != 0) {
-                       printk(KERN_DEBUG "%s: set_encrypt - non-zero idx for "
-                              "individual key\n", dev->name);
-                       return -EINVAL;
-               }
-
                sta = sta_info_get(local, sta_addr);
                if (!sta) {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG

Re: [PATCH 2/2] mac80211: ignore key index on pairwise key

[Jouni Malinen]

On Fri, Aug 17, 2007 at 11:00:19PM -0400, Volker Braun wrote:
> Our Cisco AP's set key index 3 for the PTK. This patch removes the check
> for the key index. I also tried to set idx=0 by hand, but this did not
> work (presumably because the AP then discarded my unicast packets with
> key index 0 instead of 3).

That's a broken AP, but these are likely still quite common, so it may
be better to just allow non-zero key index here for WEP. However, I
would not do this for TKIP/CCMP since they were clearly specified to
only use idx=0 for pairwise keys. Furthermore, use of non-zero key index
for pairwise keys is likely to cause problems with some hwaccel designs,
so this should really not be encouraged in any way (i.e., I would only
enable it as a client-side workaround for those broken APs doing dynamic
WEP with odd key indexes).

-- 
Jouni Malinen                                            PGP id EFC895FA

[PATCH 2/2 v2] mac80211: ignore key index on pairwise key (WEP only)

[Volker Braun]

Work-around for broken APs that use a non-zero key index for WEP
pairwise keys. With this patch, WEP encryption only is exempt from
providing a zero key index.

Signed-off-by: Volker Braun <volker.braun@physik.hu-berlin.de>


diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index fbdd1d1..2a45e54 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -385,13 +385,14 @@ static int ieee80211_set_encryption(struct net_device *dev
 
        sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
+       if (idx <0 || idx >= NUM_DEFAULT_KEYS) {
+               printk(KERN_DEBUG "%s: set_encrypt - invalid idx=%d\n",
+                      dev->name, idx);
+               return -EINVAL;
+       }
+
        if (is_broadcast_ether_addr(sta_addr)) {
                sta = NULL;
-               if (idx >= NUM_DEFAULT_KEYS) {
-                       printk(KERN_DEBUG "%s: set_encrypt - invalid idx=%d\n",
-                              dev->name, idx);
-                       return -EINVAL;
-               }
                key = sdata->keys[idx];
 
                /* TODO: consider adding hwaccel support for these; at least
@@ -405,9 +406,15 @@ static int ieee80211_set_encryption(struct net_device *dev,
                 * being, this can be only set at compile time. */
        } else {
                set_tx_key = 0;
-               if (idx != 0) {
-                       printk(KERN_DEBUG "%s: set_encrypt - non-zero idx for "
-                              "individual key\n", dev->name);
+
+               /*
+                * According to the standard, the key index of a pairwise 
+                * key must be zero. However, some AP are broken when it
+                * comes to WEP key indices, so we work around this.
+                */
+               if (idx != 0 && alg != ALG_WEP) {
+                        printk(KERN_DEBUG "%s: set_encrypt - non-zero idx for "
+                               "pairwise key\n", dev->name);
                        return -EINVAL;
                }