diff mbox

[v3,2/7] block_dev: Check permissions towards block device inode when mounting

Message ID 1447778351-118699-3-git-send-email-seth.forshee@canonical.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Seth Forshee Nov. 17, 2015, 4:39 p.m. UTC 
Unprivileged users should not be able to mount block devices when
they lack sufficient privileges towards the block device inode.
Update blkdev_get_by_path() 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.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
 fs/block_dev.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/fs/block_dev.c b/fs/block_dev.c
index f1f0aa7214a3..54d94cd64577 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1394,9 +1394,14 @@  struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
 					void *holder)
 {
 	struct block_device *bdev;
+	int perm = 0;
 	int err;
 
-	bdev = lookup_bdev(path, 0);
+	if (mode & FMODE_READ)
+		perm |= MAY_READ;
+	if (mode & FMODE_WRITE)
+		perm |= MAY_WRITE;
+	bdev = lookup_bdev(path, perm);
 	if (IS_ERR(bdev))
 		return bdev;