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mac80211: clean up skb reallocation code
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This cleans up the skb reallocation code to avoid problems with
skb->truesize, not resize an skb twice for a single output path
because we didn't expand it enough during the first copy and also
removes the code to further expand it during crypto operations
which will no longer be necessary.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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Johannes Berg authored and John W. Linville committed Jun 3, 2008
1 parent f622360 commit 23c0752
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Showing 3 changed files with 95 additions and 70 deletions.
97 changes: 68 additions & 29 deletions net/mac80211/tx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1215,13 +1215,53 @@ static int ieee80211_tx(struct net_device *dev, struct sk_buff *skb)

/* device xmit handlers */

static int ieee80211_skb_resize(struct ieee80211_local *local,
struct sk_buff *skb,
int head_need, bool may_encrypt)
{
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) {
tail_need = IEEE80211_ENCRYPT_TAILROOM;
tail_need -= skb_tailroom(skb);
tail_need = max_t(int, tail_need, 0);
}

if (head_need || tail_need) {
/* Sorry. Can't account for this any more */
skb_orphan(skb);
}

if (skb_header_cloned(skb))
I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
else
I802_DEBUG_INC(local->tx_expand_skb_head);

if (pskb_expand_head(skb, head_need, tail_need, GFP_ATOMIC)) {
printk(KERN_DEBUG "%s: failed to reallocate TX buffer\n",
wiphy_name(local->hw.wiphy));
return -ENOMEM;
}

/* update truesize too */
skb->truesize += head_need + tail_need;

return 0;
}

int ieee80211_master_start_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct net_device *odev = NULL;
struct ieee80211_sub_if_data *osdata;
int headroom;
bool may_encrypt;
int ret;

if (info->control.ifindex)
Expand All @@ -1241,13 +1281,18 @@ int ieee80211_master_start_xmit(struct sk_buff *skb,

osdata = IEEE80211_DEV_TO_SUB_IF(odev);

headroom = osdata->local->tx_headroom + IEEE80211_ENCRYPT_HEADROOM;
if (skb_headroom(skb) < headroom) {
if (pskb_expand_head(skb, headroom, 0, GFP_ATOMIC)) {
dev_kfree_skb(skb);
dev_put(odev);
return 0;
}
may_encrypt = !(info->flags & IEEE80211_TX_CTL_DO_NOT_ENCRYPT);

headroom = osdata->local->tx_headroom;
if (may_encrypt)
headroom += IEEE80211_ENCRYPT_HEADROOM;
headroom -= skb_headroom(skb);
headroom = max_t(int, 0, headroom);

if (ieee80211_skb_resize(osdata->local, skb, headroom, may_encrypt)) {
dev_kfree_skb(skb);
dev_put(odev);
return 0;
}

info->control.vif = &osdata->vif;
Expand Down Expand Up @@ -1509,32 +1554,26 @@ int ieee80211_subif_start_xmit(struct sk_buff *skb,
* build in headroom in __dev_alloc_skb() (linux/skbuff.h) and
* alloc_skb() (net/core/skbuff.c)
*/
head_need = hdrlen + encaps_len + meshhdrlen + local->tx_headroom;
head_need -= skb_headroom(skb);
head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb);

/* We are going to modify skb data, so make a copy of it if happens to
* be cloned. This could happen, e.g., with Linux bridge code passing
* us broadcast frames. */
/*
* So we need to modify the skb header and hence need a copy of
* that. The head_need variable above doesn't, so far, include
* the needed header space that we don't need right away. If we
* can, then we don't reallocate right now but only after the
* frame arrives at the master device (if it does...)
*
* If we cannot, however, then we will reallocate to include all
* the ever needed space. Also, if we need to reallocate it anyway,
* make it big enough for everything we may ever need.
*/

if (head_need > 0 || skb_header_cloned(skb)) {
#if 0
printk(KERN_DEBUG "%s: need to reallocate buffer for %d bytes "
"of headroom\n", dev->name, head_need);
#endif

if (skb_header_cloned(skb))
I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
else
I802_DEBUG_INC(local->tx_expand_skb_head);
/* Since we have to reallocate the buffer, make sure that there
* is enough room for possible WEP IV/ICV and TKIP (8 bytes
* before payload and 12 after). */
if (pskb_expand_head(skb, (head_need > 0 ? head_need + 8 : 8),
12, GFP_ATOMIC)) {
printk(KERN_DEBUG "%s: failed to reallocate TX buffer"
"\n", dev->name);
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))
goto fail;
}
}

if (encaps_data) {
Expand Down
10 changes: 3 additions & 7 deletions net/mac80211/wep.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -93,13 +93,9 @@ static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
fc |= IEEE80211_FCTL_PROTECTED;
hdr->frame_control = cpu_to_le16(fc);

if ((skb_headroom(skb) < WEP_IV_LEN ||
skb_tailroom(skb) < WEP_ICV_LEN)) {
I802_DEBUG_INC(local->tx_expand_skb_head);
if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN,
GFP_ATOMIC)))
return NULL;
}
if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
skb_headroom(skb) < WEP_IV_LEN))
return NULL;

hdrlen = ieee80211_get_hdrlen(fc);
newhdr = skb_push(skb, WEP_IV_LEN);
Expand Down
58 changes: 24 additions & 34 deletions net/mac80211/wpa.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,7 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
struct sk_buff *skb = tx->skb;
int authenticator;
int wpa_test = 0;
int tail;

fc = tx->fc;

Expand All @@ -98,16 +99,13 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
return TX_CONTINUE;
}

if (skb_tailroom(skb) < MICHAEL_MIC_LEN) {
I802_DEBUG_INC(tx->local->tx_expand_skb_head);
if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN,
MICHAEL_MIC_LEN + TKIP_ICV_LEN,
GFP_ATOMIC))) {
printk(KERN_DEBUG "%s: failed to allocate more memory "
"for Michael MIC\n", tx->dev->name);
return TX_DROP;
}
}
tail = MICHAEL_MIC_LEN;
if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
tail += TKIP_ICV_LEN;

if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < TKIP_IV_LEN))
return TX_DROP;

#if 0
authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
Expand Down Expand Up @@ -188,7 +186,7 @@ static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_key *key = tx->key;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
int hdrlen, len, tailneed;
int hdrlen, len, tail;
u16 fc;
u8 *pos;

Expand All @@ -199,25 +197,21 @@ static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
!(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
/* hwaccel - with no need for preallocated room for IV/ICV */
info->control.hw_key = &tx->key->conf;
return TX_CONTINUE;
return 0;
}

fc = le16_to_cpu(hdr->frame_control);
hdrlen = ieee80211_get_hdrlen(fc);
len = skb->len - hdrlen;

if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
tailneed = 0;
tail = 0;
else
tailneed = TKIP_ICV_LEN;

if ((skb_headroom(skb) < TKIP_IV_LEN ||
skb_tailroom(skb) < tailneed)) {
I802_DEBUG_INC(tx->local->tx_expand_skb_head);
if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN, tailneed,
GFP_ATOMIC)))
return -1;
}
tail = TKIP_ICV_LEN;

if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < TKIP_IV_LEN))
return -1;

pos = skb_push(skb, TKIP_IV_LEN);
memmove(pos, pos + TKIP_IV_LEN, hdrlen);
Expand Down Expand Up @@ -432,7 +426,7 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_key *key = tx->key;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
int hdrlen, len, tailneed;
int hdrlen, len, tail;
u16 fc;
u8 *pos, *pn, *b_0, *aad, *scratch;
int i;
Expand All @@ -445,7 +439,7 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
/* hwaccel - with no need for preallocated room for CCMP "
* header or MIC fields */
info->control.hw_key = &tx->key->conf;
return TX_CONTINUE;
return 0;
}

scratch = key->u.ccmp.tx_crypto_buf;
Expand All @@ -457,17 +451,13 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
len = skb->len - hdrlen;

if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
tailneed = 0;
tail = 0;
else
tailneed = CCMP_MIC_LEN;

if ((skb_headroom(skb) < CCMP_HDR_LEN ||
skb_tailroom(skb) < tailneed)) {
I802_DEBUG_INC(tx->local->tx_expand_skb_head);
if (unlikely(pskb_expand_head(skb, CCMP_HDR_LEN, tailneed,
GFP_ATOMIC)))
return -1;
}
tail = CCMP_MIC_LEN;

if (WARN_ON(skb_tailroom(skb) < tail ||
skb_headroom(skb) < CCMP_HDR_LEN))
return -1;

pos = skb_push(skb, CCMP_HDR_LEN);
memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
Expand Down

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