Re: [PATCH] Fix floppy ioctl (which were broken in 2.4.0-test5)

From: Tigran Aivazian (tigran@veritas.com)
Date: Sat Sep 16 2000 - 08:44:08 EST


Alain,

Al Viro, myself and Linus broke this intentionally. Please read the
comments we put in blkdev_get() in fs/block_dev.c and understand that this
is a non-trivial issue - we had an interesting conversation about it -
unfortunately all my mailfolders are gone (as a side-effect of truncate
issues :) so I can't remeber the thread subject - seek and ye shall find.

So, your patch would panic the system as it used to before the fix.

Regards,
Tigran

 On Sat, 16 Sep
2000, Alain Knaff wrote:

> The following patch (against 2.4.0-test8) restores ioctl functionality,
> which has been broken in 2.4.0-test6-pre7:
>
> --- 2.4.0-test8/linux/drivers/block/floppy.c Mon Sep 11 20:09:28 2000
> +++ linux/drivers/block/floppy.c Sat Sep 16 15:03:39 2000
> @@ -3435,6 +3435,8 @@
> static int fd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
> unsigned long param)
> {
> +#define FD_IOCTL_MODE_BIT 8
> +#define FD_IOCTL_ALLOWED ((filp) && ((filp)->f_mode & FD_IOCTL_MODE_BIT))
> #define OUT(c,x) case c: outparam = (const char *) (x); break
> #define IN(c,x,tag) case c: *(x) = inparam. tag ; return 0
>
> @@ -3502,7 +3504,7 @@
> return -EINVAL;
>
> /* permission checks */
> - if (((cmd & 0x40) && !(filp->f_mode & 2)) ||
> + if (((cmd & 0x40) && !FD_IOCTL_ALLOWED) ||
> ((cmd & 0x80) && !capable(CAP_SYS_ADMIN)))
> return -EPERM;
>
> @@ -3774,6 +3776,12 @@
> buffer_track = -1;
> invalidate_buffers(MKDEV(FLOPPY_MAJOR,old_dev));
> }
> +
> + /* Allow ioctls if we have write-permissions even if read-only open.
> + * Needed so that programs such as fdrawcmd still can work on write
> + * protected disks */
> + if ((filp->f_mode & 2) || (permission(inode,2) == 0))
> + filp->f_mode |= FD_IOCTL_MODE_BIT;
>
> if (UFDCS->rawcmd == 1)
> UFDCS->rawcmd = 2;
> -
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