Add checks for CAP_SYS_ADMIN to VIDIOC_DBG_G_REGISTER

From: Trent Piepho <xyzzy@speakeasy.org>

Before, root privileges were only needed to set hardware registers, not
to read them.  On some hardware, reading from the wrong place at the
wrong time can hang the machine.  So, to be consistent, root privileges
are required to read registers on all hardware.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>

8 files changed, 41 insertions, 91 deletions

diff --git a/linux/drivers/media/video/cx25840/cx25840-core.c b/linux/drivers/media/video/cx25840/cx25840-core.c
index 9aaaa482d..b06553a1f 100644
--- a/linux/drivers/media/video/cx25840/cx25840-core.c
+++ b/linux/drivers/media/video/cx25840/cx25840-core.c
@@ -640,15 +640,6 @@ static int cx25840_command(struct i2c_client *client, unsigned int cmd,
 	/* ioctls to allow direct access to the
 	 * cx25840 registers for testing */
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_CX25840)
-			return -EINVAL;
-		reg->val = cx25840_read(client, reg->reg & 0x0fff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
@@ -657,7 +648,10 @@ static int cx25840_command(struct i2c_client *client, unsigned int cmd,
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		cx25840_write(client, reg->reg & 0x0fff, reg->val & 0xff);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = cx25840_read(client, reg->reg & 0x0fff);
+		else
+			cx25840_write(client, reg->reg & 0x0fff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/saa7115.c b/linux/drivers/media/video/saa7115.c
index cc8ea90fd..71e1cab45 100644
--- a/linux/drivers/media/video/saa7115.c
+++ b/linux/drivers/media/video/saa7115.c
@@ -1429,15 +1429,6 @@ static int saa711x_command(struct i2c_client *client, unsigned int cmd, void *ar
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_SAA711X)
-			return -EINVAL;
-		reg->val = saa711x_read(client, reg->reg & 0xff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
@@ -1446,7 +1437,10 @@ static int saa711x_command(struct i2c_client *client, unsigned int cmd, void *ar
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		saa711x_write(client, reg->reg & 0xff, reg->val & 0xff);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = saa711x_read(client, reg->reg & 0xff);
+		else
+			saa711x_write(client, reg->reg & 0xff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/saa7127.c b/linux/drivers/media/video/saa7127.c
index 70d898697..e1e697579 100644
--- a/linux/drivers/media/video/saa7127.c
+++ b/linux/drivers/media/video/saa7127.c
@@ -627,15 +627,6 @@ static int saa7127_command(struct i2c_client *client,
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_SAA7127)
-			return -EINVAL;
-		reg->val = saa7127_read(client, reg->reg & 0xff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
@@ -644,7 +635,10 @@ static int saa7127_command(struct i2c_client *client,
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		saa7127_write(client, reg->reg & 0xff, reg->val & 0xff);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = saa7127_read(client, reg->reg & 0xff);
+		else
+			saa7127_write(client, reg->reg & 0xff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/tvp5150.c b/linux/drivers/media/video/tvp5150.c
index 582c8542f..46b97d9b1 100644
--- a/linux/drivers/media/video/tvp5150.c
+++ b/linux/drivers/media/video/tvp5150.c
@@ -1047,15 +1047,6 @@ static int tvp5150_command(struct i2c_client *c,
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_TVP5150)
-			return -EINVAL;
-		reg->val = tvp5150_read(c, reg->reg & 0xff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
@@ -1064,7 +1055,10 @@ static int tvp5150_command(struct i2c_client *c,
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		tvp5150_write(c, reg->reg & 0xff, reg->val & 0xff);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = tvp5150_read(c, reg->reg & 0xff);
+		else
+			tvp5150_write(c, reg->reg & 0xff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/upd64031a.c b/linux/drivers/media/video/upd64031a.c
index a35a21301..ae0a843ff 100644
--- a/linux/drivers/media/video/upd64031a.c
+++ b/linux/drivers/media/video/upd64031a.c
@@ -171,26 +171,18 @@ static int upd64031a_command(struct i2c_client *client, unsigned int cmd, void *
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_UPD64031A)
-			return -EINVAL;
-		reg->val = upd64031a_read(client, reg->reg & 0xff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
-		u8 addr = reg->reg & 0xff;
-		u8 val = reg->val & 0xff;
 
 		if (reg->i2c_id != I2C_DRIVERID_UPD64031A)
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		upd64031a_write(client, addr, val);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = upd64031a_read(client, reg->reg & 0xff);
+		else
+			upd64031a_write(client, reg->reg & 0xff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/upd64083.c b/linux/drivers/media/video/upd64083.c
index 6b512c5d6..61be85abd 100644
--- a/linux/drivers/media/video/upd64083.c
+++ b/linux/drivers/media/video/upd64083.c
@@ -148,26 +148,18 @@ static int upd64083_command(struct i2c_client *client, unsigned int cmd, void *a
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	case VIDIOC_DBG_G_REGISTER:
-	{
-		struct v4l2_register *reg = arg;
-
-		if (reg->i2c_id != I2C_DRIVERID_UPD64083)
-			return -EINVAL;
-		reg->val = upd64083_read(client, reg->reg & 0xff);
-		break;
-	}
-
 	case VIDIOC_DBG_S_REGISTER:
 	{
 		struct v4l2_register *reg = arg;
-		u8 addr = reg->reg & 0xff;
-		u8 val = reg->val & 0xff;
 
 		if (reg->i2c_id != I2C_DRIVERID_UPD64083)
 			return -EINVAL;
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		upd64083_write(client, addr, val);
+		if (cmd == VIDIOC_DBG_G_REGISTER)
+			reg->val = upd64083_read(client, reg->reg & 0xff);
+		else
+			upd64083_write(client, reg->reg & 0xff, reg->val & 0xff);
 		break;
 	}
 #endif
diff --git a/linux/drivers/media/video/usbvision/usbvision-video.c b/linux/drivers/media/video/usbvision/usbvision-video.c
index f23abaa27..2b8895d99 100644
--- a/linux/drivers/media/video/usbvision/usbvision-video.c
+++ b/linux/drivers/media/video/usbvision/usbvision-video.c
@@ -561,25 +561,6 @@ static int usbvision_v4l2_do_ioctl(struct inode *inode, struct file *file,
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 		/* ioctls to allow direct acces to the NT100x registers */
 		case VIDIOC_DBG_G_REGISTER:
-		{
-			struct v4l2_register *reg = arg;
-			int errCode;
-
-			if (reg->i2c_id != 0)
-				return -EINVAL;
-			/* NT100x has a 8-bit register space */
-			errCode = usbvision_read_reg(usbvision, reg->reg&0xff);
-			if (errCode < 0) {
-				err("%s: VIDIOC_DBG_G_REGISTER failed: error %d", __FUNCTION__, errCode);
-			}
-			else {
-				reg->val=(unsigned char)errCode;
-				PDEBUG(DBG_IOCTL, "VIDIOC_DBG_G_REGISTER reg=0x%02X, value=0x%02X",
-							(unsigned int)reg->reg, reg->val);
-				errCode = 0; // No error
-			}
-			return errCode;
-		}
 		case VIDIOC_DBG_S_REGISTER:
 		{
 			struct v4l2_register *reg = arg;
@@ -589,15 +570,22 @@ static int usbvision_v4l2_do_ioctl(struct inode *inode, struct file *file,
 				return -EINVAL;
 			if (!capable(CAP_SYS_ADMIN))
 				return -EPERM;
-			errCode = usbvision_write_reg(usbvision, reg->reg&0xff, reg->val);
+			/* NT100x has a 8-bit register space */
+			if (cmd == VIDIOC_DBG_G_REGISTER)
+				errCode = usbvision_read_reg(usbvision, reg->reg&0xff);
+			else
+				errCode = usbvision_write_reg(usbvision, reg->reg&0xff, reg->val);
 			if (errCode < 0) {
-				err("%s: VIDIOC_DBG_S_REGISTER failed: error %d", __FUNCTION__, errCode);
-			}
-			else {
-				PDEBUG(DBG_IOCTL, "VIDIOC_DBG_S_REGISTER reg=0x%02X, value=0x%02X",
-							(unsigned int)reg->reg, reg->val);
-				errCode = 0;
+				err("%s: VIDIOC_DBG_%c_REGISTER failed: error %d", __FUNCTION__,
+				    cmd == VIDIOC_DBG_G_REGISTER ? 'G' : 'S', errCode);
+				return errCode;
 			}
+			if (cmd == VIDIOC_DBG_S_REGISTER)
+				reg->val = (u8)errCode;
+
+			PDEBUG(DBG_IOCTL, "VIDIOC_DBG_%c_REGISTER reg=0x%02X, value=0x%02X",
+			       cmd == VIDIOC_DBG_G_REGISTER ? 'G' : 'S',
+			       (unsigned int)reg->reg, reg->val);
 			return 0;
 		}
 #endif
diff --git a/linux/drivers/media/video/videodev.c b/linux/drivers/media/video/videodev.c
index 476b3c143..707757237 100644
--- a/linux/drivers/media/video/videodev.c
+++ b/linux/drivers/media/video/videodev.c
@@ -1481,7 +1481,9 @@ static int __video_do_ioctl(struct inode *inode, struct file *file,
 	case VIDIOC_DBG_G_REGISTER:
 	{
 		struct v4l2_register *p=arg;
-		if (vfd->vidioc_g_register)
+		if (!capable(CAP_SYS_ADMIN))
+			ret=-EPERM;
+		else if (vfd->vidioc_g_register)
 			ret=vfd->vidioc_g_register(file, fh, p);
 		break;
 	}