[34-longterm 163/196] rt2500usb: fallback to SW encryption for TKIP+AES

[Paul Gortmaker]

From: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 75f64dd54a185150ebfc45e99351c890d4a2252f upstream.

HW crypto in rt2500usb does not seem to support keys with different ciphers,
which breaks TKIP+AES mode. Fall back to software encryption to fix it.

This should fix long-standing problems with rt2500usb and WPA, such as:
http://rt2x00.serialmonkey.com/phpBB/viewtopic.php?f=4&t=4834
https://bugzilla.redhat.com/show_bug.cgi?id=484888

Also tested that it does not break WEP, TKIP-only and AES-only modes.

Signed-off-by: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Gertjan van Wingerde <gwingerde@xxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/net/wireless/rt2x00/rt2500usb.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c
index 8ebb705..2961228 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/rt2x00/rt2500usb.c
@@ -348,6 +348,7 @@ static int rt2500usb_config_key(struct rt2x00_dev *rt2x00dev,
 	int timeout;
 	u32 mask;
 	u16 reg;
+	enum cipher curr_cipher;
 
 	if (crypto->cmd == SET_KEY) {
 		/*
@@ -358,6 +359,7 @@ static int rt2500usb_config_key(struct rt2x00_dev *rt2x00dev,
 		mask = TXRX_CSR0_KEY_ID.bit_mask;
 
 		rt2500usb_register_read(rt2x00dev, TXRX_CSR0, &reg);
+		curr_cipher = rt2x00_get_field16(reg, TXRX_CSR0_ALGORITHM);
 		reg &= mask;
 
 		if (reg && reg == mask)
@@ -366,6 +368,14 @@ static int rt2500usb_config_key(struct rt2x00_dev *rt2x00dev,
 		reg = rt2x00_get_field16(reg, TXRX_CSR0_KEY_ID);
 
 		key->hw_key_idx += reg ? ffz(reg) : 0;
+		/*
+		 * Hardware requires that all keys use the same cipher
+		 * (e.g. TKIP-only, AES-only, but not TKIP+AES).
+		 * If this is not the first key, compare the cipher with the
+		 * first one and fall back to SW crypto if not the same.
+		 */
+		if (key->hw_key_idx > 0 && crypto->cipher != curr_cipher)
+			return -EOPNOTSUPP;
 
 		/*
 		 * The encryption key doesn't fit within the CSR cache,
-- 
1.7.9.3

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