Based on inputs from Johannes Berg <[email protected]>
from http://markmail.org/thread/t4acssvlgb5gamt2 and
http://markmail.org/thread/mydlihrhvfvevuim
In xmit path, devices that do full hardware crypto (including
MMIC and ICV) need no tailroom. For such devices, tailroom
reservation can be skipped if all the keys are programmed into
the hardware (i.e software crypto is not used for any of the
keys) and none of the keys wants software to generate Michael
MIC and IV.
v2: Added check for IV along with MMIC to avoid
>WARNING: at net/mac80211/wep.c:101 ieee80211_wep_add_iv+0x56/0xf3()
Reported-by: Fabio Rossi <[email protected]>
Tested-by: Fabio Rossi <[email protected]>
Signed-off-by: Mohammed Shafi Shajakhan <[email protected]>
Cc: Mohammed Shafi Shajakhan <[email protected]>
v3: Fixing races to avoid
>WARNING: at net/mac80211/wpa.c:397 ccmp_encrypt_skb+0xc4/0x1f0
Reported-by: Andreas Hartmann <[email protected]>
Tested-by: Andreas Hartmann <[email protected]>
Signed-off-by: Yogesh Ashok Powar <[email protected]>
---
net/mac80211/ieee80211_i.h | 3 ++
net/mac80211/key.c | 51 ++++++++++++++++++++++++++++++++++++++++++-
net/mac80211/tx.c | 14 ++++-------
3 files changed, 57 insertions(+), 11 deletions(-)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 25c15cc..4f2e424 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -544,6 +544,9 @@ struct ieee80211_sub_if_data {
/* keys */
struct list_head key_list;
+ /* count for keys needing tailroom space allocation */
+ int crypto_tx_tailroom_needed_cnt;
+
struct net_device *dev;
struct ieee80211_local *local;
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index f825e2f..aea5a71 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -61,6 +61,36 @@ static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
return NULL;
}
+static void increment_tailroom_need_count(struct ieee80211_sub_if_data *sdata)
+{
+ /*
+ * When this count is zero, SKB resizing for allocating tailroom
+ * for IV or MMIC is skipped. But, this check has created two race
+ * cases in xmit path while transiting from zero count to one:
+ *
+ * 1. SKB resize was skipped because no key was added but just before
+ * the xmit key is added and SW encryption kicks off.
+ *
+ * 2. SKB resize was skipped because all the keys were hw planted but
+ * just before xmit one of the key is deleted and SW encryption kicks
+ * off.
+ *
+ * In both the above case SW encryption will find not enough space for
+ * tailroom and exits with WARN_ON. (See WARN_ONs at wpa.c)
+ *
+ * Solution has been explained at
+ * http://markmail.org/message/c3ykchyv6azzmdum
+ */
+
+ if (!sdata->crypto_tx_tailroom_needed_cnt++) {
+ /*
+ * Flush all XMIT packets currently using HW encryption or no
+ * encryption at all if the count transition is from 0 -> 1.
+ */
+ synchronize_net();
+ }
+}
+
static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
{
struct ieee80211_sub_if_data *sdata;
@@ -101,6 +131,11 @@ static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
if (!ret) {
key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
+
+ if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+ (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
+ sdata->crypto_tx_tailroom_needed_cnt--;
+
return 0;
}
@@ -142,6 +177,10 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
sta = get_sta_for_key(key);
sdata = key->sdata;
+ if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+ (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
+ increment_tailroom_need_count(sdata);
+
if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
sdata = container_of(sdata->bss,
struct ieee80211_sub_if_data,
@@ -394,8 +433,10 @@ static void __ieee80211_key_destroy(struct ieee80211_key *key)
ieee80211_aes_key_free(key->u.ccmp.tfm);
if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC)
ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
- if (key->local)
+ if (key->local) {
ieee80211_debugfs_key_remove(key);
+ key->sdata->crypto_tx_tailroom_needed_cnt--;
+ }
kfree(key);
}
@@ -452,6 +493,8 @@ int ieee80211_key_link(struct ieee80211_key *key,
else
old_key = key_mtx_dereference(sdata->local, sdata->keys[idx]);
+ increment_tailroom_need_count(sdata);
+
__ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
__ieee80211_key_destroy(old_key);
@@ -498,8 +541,12 @@ void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
mutex_lock(&sdata->local->key_mtx);
- list_for_each_entry(key, &sdata->key_list, list)
+ sdata->crypto_tx_tailroom_needed_cnt = 0;
+
+ list_for_each_entry(key, &sdata->key_list, list) {
+ increment_tailroom_need_count(sdata);
ieee80211_key_enable_hw_accel(key);
+ }
mutex_unlock(&sdata->local->key_mtx);
}
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 3104c84..e8d0d2d 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1474,18 +1474,14 @@ static bool ieee80211_tx(struct ieee80211_sub_if_data *sdata,
/* device xmit handlers */
-static int ieee80211_skb_resize(struct ieee80211_local *local,
+static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata,
struct sk_buff *skb,
int head_need, bool may_encrypt)
{
+ struct ieee80211_local *local = sdata->local;
int tail_need = 0;
- /*
- * This could be optimised, devices that do full hardware
- * crypto (including TKIP MMIC) need no tailroom... But we
- * have no drivers for such devices currently.
- */
- if (may_encrypt) {
+ if (may_encrypt && sdata->crypto_tx_tailroom_needed_cnt) {
tail_need = IEEE80211_ENCRYPT_TAILROOM;
tail_need -= skb_tailroom(skb);
tail_need = max_t(int, tail_need, 0);
@@ -1578,7 +1574,7 @@ static void ieee80211_xmit(struct ieee80211_sub_if_data *sdata,
headroom -= skb_headroom(skb);
headroom = max_t(int, 0, headroom);
- if (ieee80211_skb_resize(local, skb, headroom, may_encrypt)) {
+ if (ieee80211_skb_resize(sdata, skb, headroom, may_encrypt)) {
dev_kfree_skb(skb);
rcu_read_unlock();
return;
@@ -1945,7 +1941,7 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
head_need += IEEE80211_ENCRYPT_HEADROOM;
head_need += local->tx_headroom;
head_need = max_t(int, 0, head_need);
- if (ieee80211_skb_resize(local, skb, head_need, true))
+ if (ieee80211_skb_resize(sdata, skb, head_need, true))
goto fail;
}
--
1.5.4.1
On Tue, 2011-06-28 at 17:58 +0530, Yogesh Ashok Powar wrote:
> Based on inputs from Johannes Berg <[email protected]>
> from http://markmail.org/thread/t4acssvlgb5gamt2 and
> http://markmail.org/thread/mydlihrhvfvevuim
>
> In xmit path, devices that do full hardware crypto (including
> MMIC and ICV) need no tailroom. For such devices, tailroom
> reservation can be skipped if all the keys are programmed into
> the hardware (i.e software crypto is not used for any of the
> keys) and none of the keys wants software to generate Michael
> MIC and IV.
>
> v2: Added check for IV along with MMIC to avoid
> >WARNING: at net/mac80211/wep.c:101 ieee80211_wep_add_iv+0x56/0xf3()
> Reported-by: Fabio Rossi <[email protected]>
> Tested-by: Fabio Rossi <[email protected]>
> Signed-off-by: Mohammed Shafi Shajakhan <[email protected]>
> Cc: Mohammed Shafi Shajakhan <[email protected]>
>
> v3: Fixing races to avoid
> >WARNING: at net/mac80211/wpa.c:397 ccmp_encrypt_skb+0xc4/0x1f0
> Reported-by: Andreas Hartmann <[email protected]>
> Tested-by: Andreas Hartmann <[email protected]>
> Signed-off-by: Yogesh Ashok Powar <[email protected]>
This changelog entry is kinda messed up.
> + * Solution has been explained at
> + * http://markmail.org/message/c3ykchyv6azzmdum
Nothing against markmail, but I prefer links that contain a message ID
so if the link ever goes dead, you can google for the message ID. Maybe
use
http://mid.gmane.org/[email protected]
johannes