On 22/12/2017 10:32 PM, Dongsu Park wrote: > From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > > When looking up a block device by path no permission check is > done to verify that the user has access to the block device inode > at the specified path. In some cases it may be necessary to > check permissions towards the inode, such as allowing > unprivileged users to mount block devices in user namespaces. > > Add an argument to lookup_bdev() to optionally perform this > permission check. A value of 0 skips the permission check and > behaves the same as before. A non-zero value specifies the mask > of access rights required towards the inode at the specified > path. The check is always skipped if the user has CAP_SYS_ADMIN. > > All callers of lookup_bdev() currently pass a mask of 0, so this > patch results in no functional change. Subsequent patches will > add permission checks where appropriate. > > Patch v4 is available: https://patchwork.kernel.org/patch/8943601/ > > Cc: dm-devel@xxxxxxxxxx > Cc: linux-bcache@xxxxxxxxxxxxxxx > Cc: linux-fsdevel@xxxxxxxxxxxxxxx > Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> > Cc: Jan Kara <jack@xxxxxxxx> > Cc: Serge Hallyn <serge@xxxxxxxxxx> > Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > Signed-off-by: Dongsu Park <dongsu@xxxxxxxxxx> Hi Dongsu, Could you please use a macro like NO_PERMISSION_CHECK to replace hard coded 0 ? At least for me, I don't need to check what does 0 mean in the new lookup_bdev(). Thanks. Coly Li > --- > drivers/md/bcache/super.c | 2 +- > drivers/md/dm-table.c | 2 +- > drivers/mtd/mtdsuper.c | 2 +- > fs/block_dev.c | 13 ++++++++++--- > fs/quota/quota.c | 2 +- > include/linux/fs.h | 2 +- > 6 files changed, 15 insertions(+), 8 deletions(-) > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index b4d28928..acc9d56c 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -1967,7 +1967,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, > sb); > if (IS_ERR(bdev)) { > if (bdev == ERR_PTR(-EBUSY)) { > - bdev = lookup_bdev(strim(path)); > + bdev = lookup_bdev(strim(path), 0); > mutex_lock(&bch_register_lock); > if (!IS_ERR(bdev) && bch_is_open(bdev)) > err = "device already registered"; > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 88130b5d..bca5eaf4 100644 [snip] -- Coly Li -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
