rt2x00: Validate firmware in driver

The get_firmware_crc() callback function isn't flexible
enough when dealing with multiple firmware versions.
It might in some cases be possible that the firmware
file contains multiple CRC checksums.

Create the check_firmware() callback function where the driver
has complete freedom in how to validate the firmware.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00.h

@@ -468,9 +468,10 @@ struct rt2x00lib_ops {
 	 */
 	int (*probe_hw) (struct rt2x00_dev *rt2x00dev);
 	char *(*get_firmware_name) (struct rt2x00_dev *rt2x00dev);
-	u16 (*get_firmware_crc) (const void *data, const size_t len);
-	int (*load_firmware) (struct rt2x00_dev *rt2x00dev, const void *data,
-			      const size_t len);
+	int (*check_firmware) (struct rt2x00_dev *rt2x00dev,
+			       const u8 *data, const size_t len);
+	int (*load_firmware) (struct rt2x00_dev *rt2x00dev,
+			      const u8 *data, const size_t len);
 
 	/*
 	 * Device initialization/deinitialization handlers.

drivers/net/wireless/rt2x00/rt2x00firmware.c

@@ -35,7 +35,6 @@ static int rt2x00lib_request_firmware(struct rt2x00_dev *rt2x00dev)
 	const struct firmware *fw;
 	char *fw_name;
 	int retval;
-	u16 crc;
 
 	/*
 	 * Read correct firmware from harddisk.
@@ -61,16 +60,26 @@ static int rt2x00lib_request_firmware(struct rt2x00_dev *rt2x00dev)
 		return -ENOENT;
 	}
 
-	crc = rt2x00dev->ops->lib->get_firmware_crc(fw->data, fw->size);
-	if (crc != (fw->data[fw->size - 2] << 8 | fw->data[fw->size - 1])) {
-		ERROR(rt2x00dev, "Firmware checksum error.\n");
-		retval = -ENOENT;
-		goto exit;
-	}
-
 	INFO(rt2x00dev, "Firmware detected - version: %d.%d.\n",
 	     fw->data[fw->size - 4], fw->data[fw->size - 3]);
 
+	retval = rt2x00dev->ops->lib->check_firmware(rt2x00dev, fw->data, fw->size);
+	switch (retval) {
+	case FW_OK:
+		break;
+	case FW_BAD_CRC:
+		ERROR(rt2x00dev, "Firmware checksum error.\n");
+		goto exit;
+	case FW_BAD_LENGTH:
+		ERROR(rt2x00dev,
+		      "Invalid firmware file length (len=%zu)\n", fw->size);
+		goto exit;
+	case FW_BAD_VERSION:
+		ERROR(rt2x00dev,
+		      "Current firmware does not support detected chipset.\n");
+		goto exit;
+	};
+
 	rt2x00dev->fw = fw;
 
 	return 0;
@@ -78,7 +87,7 @@ static int rt2x00lib_request_firmware(struct rt2x00_dev *rt2x00dev)
 exit:
 	release_firmware(fw);
 
-	return retval;
+	return -ENOENT;
 }
 
 int rt2x00lib_load_firmware(struct rt2x00_dev *rt2x00dev)

drivers/net/wireless/rt2x00/rt2x00reg.h

@@ -134,6 +134,16 @@ enum rate_modulation {
 	RATE_MODE_HT_GREENFIELD = 3,
 };
 
+/*
+ * Firmware validation error codes
+ */
+enum firmware_errors {
+	FW_OK,
+	FW_BAD_CRC,
+	FW_BAD_LENGTH,
+	FW_BAD_VERSION,
+};
+
 /*
  * Register handlers.
  * We store the position of a register field inside a field structure,

drivers/net/wireless/rt2x00/rt61pci.c

@@ -1176,34 +1176,41 @@ static char *rt61pci_get_firmware_name(struct rt2x00_dev *rt2x00dev)
 	return fw_name;
 }
 
-static u16 rt61pci_get_firmware_crc(const void *data, const size_t len)
+static int rt61pci_check_firmware(struct rt2x00_dev *rt2x00dev,
+				  const u8 *data, const size_t len)
 {
+	u16 fw_crc;
 	u16 crc;
 
 	/*
-	 * Use the crc itu-t algorithm.
+	 * Only support 8kb firmware files.
+	 */
+	if (len != 8192)
+		return FW_BAD_LENGTH;
+
+	/*
 	 * The last 2 bytes in the firmware array are the crc checksum itself,
 	 * this means that we should never pass those 2 bytes to the crc
 	 * algorithm.
 	 */
+	fw_crc = (data[len - 2] << 8 | data[len - 1]);
+
+	/*
+	 * Use the crc itu-t algorithm.
+	 */
 	crc = crc_itu_t(0, data, len - 2);
 	crc = crc_itu_t_byte(crc, 0);
 	crc = crc_itu_t_byte(crc, 0);
 
-	return crc;
+	return (fw_crc == crc) ? FW_OK : FW_BAD_CRC;
 }
 
-static int rt61pci_load_firmware(struct rt2x00_dev *rt2x00dev, const void *data,
-				 const size_t len)
+static int rt61pci_load_firmware(struct rt2x00_dev *rt2x00dev,
+				 const u8 *data, const size_t len)
 {
 	int i;
 	u32 reg;
 
-	if (len != 8192) {
-		ERROR(rt2x00dev, "Invalid firmware file length (len=%zu)\n", len);
-		return -ENOENT;
-	}
-
 	/*
 	 * Wait for stable hardware.
 	 */
@@ -2750,7 +2757,7 @@ static const struct rt2x00lib_ops rt61pci_rt2x00_ops = {
 	.irq_handler		= rt61pci_interrupt,
 	.probe_hw		= rt61pci_probe_hw,
 	.get_firmware_name	= rt61pci_get_firmware_name,
-	.get_firmware_crc	= rt61pci_get_firmware_crc,
+	.check_firmware		= rt61pci_check_firmware,
 	.load_firmware		= rt61pci_load_firmware,
 	.initialize		= rt2x00pci_initialize,
 	.uninitialize		= rt2x00pci_uninitialize,

drivers/net/wireless/rt2x00/rt73usb.c

@@ -1061,35 +1061,42 @@ static char *rt73usb_get_firmware_name(struct rt2x00_dev *rt2x00dev)
 	return FIRMWARE_RT2571;
 }
 
-static u16 rt73usb_get_firmware_crc(const void *data, const size_t len)
+static int rt73usb_check_firmware(struct rt2x00_dev *rt2x00dev,
+				  const u8 *data, const size_t len)
 {
+	u16 fw_crc;
 	u16 crc;
 
 	/*
-	 * Use the crc itu-t algorithm.
+	 * Only support 2kb firmware files.
+	 */
+	if (len != 2048)
+		return FW_BAD_LENGTH;
+
+	/*
 	 * The last 2 bytes in the firmware array are the crc checksum itself,
 	 * this means that we should never pass those 2 bytes to the crc
 	 * algorithm.
 	 */
+	fw_crc = (data[len - 2] << 8 | data[len - 1]);
+
+	/*
+	 * Use the crc itu-t algorithm.
+	 */
 	crc = crc_itu_t(0, data, len - 2);
 	crc = crc_itu_t_byte(crc, 0);
 	crc = crc_itu_t_byte(crc, 0);
 
-	return crc;
+	return (fw_crc == crc) ? FW_OK : FW_BAD_CRC;
 }
 
-static int rt73usb_load_firmware(struct rt2x00_dev *rt2x00dev, const void *data,
-				 const size_t len)
+static int rt73usb_load_firmware(struct rt2x00_dev *rt2x00dev,
+				 const u8 *data, const size_t len)
 {
 	unsigned int i;
 	int status;
 	u32 reg;
 
-	if (len != 2048) {
-		ERROR(rt2x00dev, "Invalid firmware file length (len=%zu)\n", len);
-		return -ENOENT;
-	}
-
 	/*
 	 * Wait for stable hardware.
 	 */
@@ -2278,7 +2285,7 @@ static const struct ieee80211_ops rt73usb_mac80211_ops = {
 static const struct rt2x00lib_ops rt73usb_rt2x00_ops = {
 	.probe_hw		= rt73usb_probe_hw,
 	.get_firmware_name	= rt73usb_get_firmware_name,
-	.get_firmware_crc	= rt73usb_get_firmware_crc,
+	.check_firmware		= rt73usb_check_firmware,
 	.load_firmware		= rt73usb_load_firmware,
 	.initialize		= rt2x00usb_initialize,
 	.uninitialize		= rt2x00usb_uninitialize,