lkml.org 
[lkml]   [2017]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 02/11] mtd: Check permissions towards mtd block device inode when mounting
Date
From: Seth Forshee <seth.forshee@canonical.com>

Unprivileged users should not be able to mount mtd block devices
when they lack sufficient privileges towards the block device
inode. Update mount_mtd() to validate that the user has the
required access to the inode at the specified path. The check
will be skipped for CAP_SYS_ADMIN, so privileged mounts will
continue working as before.

Patch v3 is available: https://patchwork.kernel.org/patch/7640011/

Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Dongsu Park <dongsu@kinvolk.io>
---
drivers/mtd/mtdsuper.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
index 4a4d40c0..3c8734f3 100644
--- a/drivers/mtd/mtdsuper.c
+++ b/drivers/mtd/mtdsuper.c
@@ -129,6 +129,7 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
#ifdef CONFIG_BLOCK
struct block_device *bdev;
int ret, major;
+ int perm;
#endif
int mtdnr;

@@ -180,7 +181,10 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
/* try the old way - the hack where we allowed users to mount
* /dev/mtdblock$(n) but didn't actually _use_ the blockdev
*/
- bdev = lookup_bdev(dev_name, 0);
+ perm = MAY_READ;
+ if (!(flags & MS_RDONLY))
+ perm |= MAY_WRITE;
+ bdev = lookup_bdev(dev_name, perm);
if (IS_ERR(bdev)) {
ret = PTR_ERR(bdev);
pr_debug("MTDSB: lookup_bdev() returned %d\n", ret);
--
2.13.6
\
 
 \ /
  Last update: 2017-12-22 17:09    [W:0.661 / U:4.508 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site