[PATCH] mtd: require write permissions for locking and badblock ioctls

[Michael Walle]

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: f7e6b19bc764 ("mtd: properly check all write ioctls for permissions")
Signed-off-by: Michael Walle <mich...@walle.cc>
---
 drivers/mtd/mtdchar.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 57c4a2f0b703..30c8273c1eff 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -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;
-- 
2.20.1