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nbd: fix ioctl permissions

PATCH New Paul Clements 1 participant 1 message Jan 24, 2005

Subsystems (2)
Block layer Network block device (NBD)
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Paul Clements

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PATCH 1/1 nbd: fix ioctl permissions

Hi Marcelo,

Here's a patch for nbd that Rogier recently sent me. It allows non-root to do BLKGETSIZE, et al. on nbd devices, which he needs for his data recovery applications.

Tested against 2.4.29. Please apply.

Thanks,
Paul

From: Rogier Wolff <[email protected]>

Signed-off-by Paul Clements <[email protected]>

Description: We shouldn't need CAP_SYS_ADMIN to ask for disk capacity and such.

===

drivers/block/nbd.c +14 -7
diff -ur linux-2.4.28.clean/drivers/block/nbd.c linux-2.4.28.nbd-fix/drivers/block/nbd.c
@@ -408,10 +408,7 @@
 	int dev, error, temp;
 	struct request sreq ;
 
-	/* Anyone capable of this syscall can do *real bad* things */
 
-	if (!capable(CAP_SYS_ADMIN))
-		return -EPERM;
 	if (!inode)
 		return -EINVAL;
 	dev = MINOR(inode->i_rdev);

@@ -419,6 +416,20 @@
 		return -ENODEV;
 
 	lo = &nbd_dev[dev];
+
+	/* these are innocent, but.... */
+	switch (cmd) {
+	case BLKGETSIZE:
+		return put_user(nbd_bytesizes[dev] >> 9, (unsigned long *) arg);
+	case BLKGETSIZE64:
+		return put_user((u64)nbd_bytesizes[dev], (u64 *) arg);
+	}
+
+	/* ... anyone capable of any of the below ioctls can do *real bad* 
+	   things */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
 	switch (cmd) {
 	case NBD_DISCONNECT:
 	        printk("NBD_DISCONNECT\n");

@@ -524,10 +535,6 @@
 		       dev, lo->queue_head.next, lo->queue_head.prev, requests_in, requests_out);
 		return 0;
 #endif
-	case BLKGETSIZE:
-		return put_user(nbd_bytesizes[dev] >> 9, (unsigned long *) arg);
-	case BLKGETSIZE64:
-		return put_user((u64)nbd_bytesizes[dev], (u64 *) arg);
 	}
 	return -EINVAL;
 }