b43: Drop packets that we are not able to encrypt

We must not transmit packets we're not able to encrypt.

This fixes a bug where in a tiny timeframe after machine resume
packets can get sent unencrypted and might leak information.

This also fixes three small resource leakages I spotted while fixing
the security problem. Properly deallocate the DMA slots in any DMA
allocation error path.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 58 insertions, 30 deletions

diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index 3e73d2a523aa..8a708b77925d 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -1114,7 +1114,7 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
 {
         const struct b43_dma_ops *ops = ring->ops;
         u8 *header;
-        int slot;
+        int slot, old_top_slot, old_used_slots;
         int err;
         struct b43_dmadesc_generic *desc;
         struct b43_dmadesc_meta *meta;
@@ -1126,6 +1126,9 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
 #define SLOTS_PER_PACKET  2
         B43_WARN_ON(skb_shinfo(skb)->nr_frags);
 
+        old_top_slot = ring->current_slot;
+        old_used_slots = ring->used_slots;
+
         /* Get a slot for the header. */
         slot = request_slot(ring);
         desc = ops->idx2desc(ring, slot, &meta_hdr);
@@ -1133,13 +1136,21 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
 
         header = &(ring->txhdr_cache[slot * hdrsize]);
         cookie = generate_cookie(ring, slot);
-        b43_generate_txhdr(ring->dev, header,
-                           skb->data, skb->len, ctl, cookie);
+        err = b43_generate_txhdr(ring->dev, header,
+                                 skb->data, skb->len, ctl, cookie);
+        if (unlikely(err)) {
+                ring->current_slot = old_top_slot;
+                ring->used_slots = old_used_slots;
+                return err;
+        }
 
         meta_hdr->dmaaddr = map_descbuffer(ring, (unsigned char *)header,
                                            hdrsize, 1);
-        if (dma_mapping_error(meta_hdr->dmaaddr))
+        if (dma_mapping_error(meta_hdr->dmaaddr)) {
+                ring->current_slot = old_top_slot;
+                ring->used_slots = old_used_slots;
                 return -EIO;
+        }
         ops->fill_descriptor(ring, desc, meta_hdr->dmaaddr,
                              hdrsize, 1, 0, 0);
 
@@ -1157,6 +1168,8 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
         if (dma_mapping_error(meta->dmaaddr)) {
                 bounce_skb = __dev_alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
                 if (!bounce_skb) {
+                        ring->current_slot = old_top_slot;
+                        ring->used_slots = old_used_slots;
                         err = -ENOMEM;
                         goto out_unmap_hdr;
                 }
@@ -1167,6 +1180,8 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
                 meta->skb = skb;
                 meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
                 if (dma_mapping_error(meta->dmaaddr)) {
+                        ring->current_slot = old_top_slot;
+                        ring->used_slots = old_used_slots;
                         err = -EIO;
                         goto out_free_bounce;
                 }
@@ -1252,6 +1267,13 @@ int b43_dma_tx(struct b43_wldev *dev,
         B43_WARN_ON(ring->stopped);
 
         err = dma_tx_fragment(ring, skb, ctl);
+        if (unlikely(err == -ENOKEY)) {
+                /* Drop this packet, as we don't have the encryption key
+                 * anymore and must not transmit it unencrypted. */
+                dev_kfree_skb_any(skb);
+                err = 0;
+                goto out_unlock;
+        }
         if (unlikely(err)) {
                 b43err(dev->wl, "DMA tx mapping failure\n");
                 goto out_unlock;
diff --git a/drivers/net/wireless/b43/xmit.c b/drivers/net/wireless/b43/xmit.c
index 7de2814d527e..7caa26eb4105 100644
--- a/drivers/net/wireless/b43/xmit.c
+++ b/drivers/net/wireless/b43/xmit.c
@@ -178,12 +178,12 @@ static u8 b43_calc_fallback_rate(u8 bitrate)
 }
 
 /* Generate a TX data header. */
-void b43_generate_txhdr(struct b43_wldev *dev,
-                        u8 *_txhdr,
-                        const unsigned char *fragment_data,
-                        unsigned int fragment_len,
-                        const struct ieee80211_tx_control *txctl,
-                        u16 cookie)
+int b43_generate_txhdr(struct b43_wldev *dev,
+                       u8 *_txhdr,
+                       const unsigned char *fragment_data,
+                       unsigned int fragment_len,
+                       const struct ieee80211_tx_control *txctl,
+                       u16 cookie)
 {
         struct b43_txhdr *txhdr = (struct b43_txhdr *)_txhdr;
         const struct b43_phy *phy = &dev->phy;
@@ -238,22 +238,27 @@ void b43_generate_txhdr(struct b43_wldev *dev,
                 B43_WARN_ON(key_idx >= dev->max_nr_keys);
                 key = &(dev->key[key_idx]);
 
-                if (likely(key->keyconf)) {
-                        /* This key is valid. Use it for encryption. */
-
-                        /* Hardware appends ICV. */
-                        plcp_fragment_len += txctl->icv_len;
-
-                        key_idx = b43_kidx_to_fw(dev, key_idx);
-                        mac_ctl |= (key_idx << B43_TXH_MAC_KEYIDX_SHIFT) &
-                                   B43_TXH_MAC_KEYIDX;
-                        mac_ctl |= (key->algorithm << B43_TXH_MAC_KEYALG_SHIFT) &
-                                   B43_TXH_MAC_KEYALG;
-                        wlhdr_len = ieee80211_get_hdrlen(fctl);
-                        iv_len = min((size_t) txctl->iv_len,
-                                     ARRAY_SIZE(txhdr->iv));
-                        memcpy(txhdr->iv, ((u8 *) wlhdr) + wlhdr_len, iv_len);
+                if (unlikely(!key->keyconf)) {
+                        /* This key is invalid. This might only happen
+                         * in a short timeframe after machine resume before
+                         * we were able to reconfigure keys.
+                         * Drop this packet completely. Do not transmit it
+                         * unencrypted to avoid leaking information. */
+                        return -ENOKEY;
                 }
+
+                /* Hardware appends ICV. */
+                plcp_fragment_len += txctl->icv_len;
+
+                key_idx = b43_kidx_to_fw(dev, key_idx);
+                mac_ctl |= (key_idx << B43_TXH_MAC_KEYIDX_SHIFT) &
+                           B43_TXH_MAC_KEYIDX;
+                mac_ctl |= (key->algorithm << B43_TXH_MAC_KEYALG_SHIFT) &
+                           B43_TXH_MAC_KEYALG;
+                wlhdr_len = ieee80211_get_hdrlen(fctl);
+                iv_len = min((size_t) txctl->iv_len,
+                             ARRAY_SIZE(txhdr->iv));
+                memcpy(txhdr->iv, ((u8 *) wlhdr) + wlhdr_len, iv_len);
         }
         if (b43_is_old_txhdr_format(dev)) {
                 b43_generate_plcp_hdr((struct b43_plcp_hdr4 *)(&txhdr->old_format.plcp),
@@ -411,6 +416,7 @@ void b43_generate_txhdr(struct b43_wldev *dev,
         txhdr->phy_ctl = cpu_to_le16(phy_ctl);
         txhdr->extra_ft = extra_ft;
 
+        return 0;
 }
 
 static s8 b43_rssi_postprocess(struct b43_wldev *dev,
diff --git a/drivers/net/wireless/b43/xmit.h b/drivers/net/wireless/b43/xmit.h
index ca2a2ab8654c..41765039552b 100644
--- a/drivers/net/wireless/b43/xmit.h
+++ b/drivers/net/wireless/b43/xmit.h
@@ -174,11 +174,11 @@ size_t b43_txhdr_size(struct b43_wldev *dev)
 }
 
 
-void b43_generate_txhdr(struct b43_wldev *dev,
-                        u8 * txhdr,
-                        const unsigned char *fragment_data,
-                        unsigned int fragment_len,
-                        const struct ieee80211_tx_control *txctl, u16 cookie);
+int b43_generate_txhdr(struct b43_wldev *dev,
+                       u8 * txhdr,
+                       const unsigned char *fragment_data,
+                       unsigned int fragment_len,
+                       const struct ieee80211_tx_control *txctl, u16 cookie);
 
 /* Transmit Status */
 struct b43_txstatus {