Commit 1e97743f authored Mar 03, 2021 by Michael Walle Committed by Miquel Raynal Mar 28, 2021

mtd: require write permissions for locking and badblock ioctls



MEMLOCK, MEMUNLOCK and OTPLOCK modify protection bits. Thus require
write permission. Depending on the hardware MEMLOCK might even be
write-once, e.g. for SPI-NOR flashes with their WP# tied to GND. OTPLOCK
is always write-once.

MEMSETBADBLOCK modifies the bad block table.

Fixes: f7e6b19b ("mtd: properly check all write ioctls for permissions")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210303155735.25887-1-michael@walle.cc

parent 3ba6d1ff

drivers/mtd/mtdchar.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -643,16 +643,12 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg)
		case MEMGETINFO:
		case MEMREADOOB:
		case MEMREADOOB64:
		case MEMLOCK:
		case MEMUNLOCK:
		case MEMISLOCKED:
		case MEMGETOOBSEL:
		case MEMGETBADBLOCK:
		case MEMSETBADBLOCK:
		case OTPSELECT:
		case OTPGETREGIONCOUNT:
		case OTPGETREGIONINFO:
		case OTPLOCK:
		case ECCGETLAYOUT:
		case ECCGETSTATS:
		case MTDFILEMODE:
		@@ -663,9 +659,13 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg)
		/* "dangerous" commands */
		case MEMERASE:
		case MEMERASE64:
		case MEMLOCK:
		case MEMUNLOCK:
		case MEMSETBADBLOCK:
		case MEMWRITEOOB:
		case MEMWRITEOOB64:
		case MEMWRITE:
		case OTPLOCK:
		if (!(file->f_mode & FMODE_WRITE))
		return -EPERM;
		break;