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>

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,
+	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;

drivers/net/wireless/b43/xmit.c

@@ -178,7 +178,7 @@ static u8 b43_calc_fallback_rate(u8 bitrate)
 }
 
 /* Generate a TX data header. */
-void b43_generate_txhdr(struct b43_wldev *dev,
+int b43_generate_txhdr(struct b43_wldev *dev,
 		       u8 *_txhdr,
 		       const unsigned char *fragment_data,
 		       unsigned int fragment_len,
@@ -238,8 +238,14 @@ 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. */
+		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;
@@ -254,7 +260,6 @@ void b43_generate_txhdr(struct b43_wldev *dev,
 			     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),
 				      plcp_fragment_len, rate);
@@ -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,

drivers/net/wireless/b43/xmit.h

@@ -174,7 +174,7 @@ size_t b43_txhdr_size(struct b43_wldev *dev)
 }
 
 
-void b43_generate_txhdr(struct b43_wldev *dev,
+int b43_generate_txhdr(struct b43_wldev *dev,
 		       u8 * txhdr,
 		       const unsigned char *fragment_data,
 		       unsigned int fragment_len,