On Fri, Apr 27, 2018 at 01:30:53PM +0200, Thomas-Mich Richter wrote:
> On 04/27/2018 12:06 PM, Greg KH wrote:
> > On Fri, Apr 27, 2018 at 11:14:26AM +0200, Thomas-Mich Richter wrote:
> >> On 04/27/2018 10:27 AM, Greg KH wrote:
> >>> On Fri, Apr 27, 2018 at 10:07:12AM +0200, Thomas Richter wrote:
> >>>> Currently function debugfs_create_dir() creates a new
> >>>> directory in the debugfs (usually mounted /sys/kernel/debug)
> >>>> with permission rwxr-xr-x. This is hard coded.
> >>>>
> >>>> Change this to use the parent directory permission.
> >>>>
> >>>> Fixes: edac65eaf8d5c ("debugfs: take mode-dependent parts of
> >>>> debugfs_get_inode() into callers")
> >>>> Signed-off-by: Thomas Richter <tmri...@linux.ibm.com>
> >>>> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> >>>> ---
> >>>> fs/debugfs/inode.c | 5 ++++-
> >>>> 1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> >>>> index 13b01351dd1c..80618330d86a 100644
> >>>> --- a/fs/debugfs/inode.c
> >>>> +++ b/fs/debugfs/inode.c
> >>>> @@ -512,7 +512,10 @@ struct dentry *debugfs_create_dir(const char *name,
> >>>> struct dentry *parent)
> >>>> if (unlikely(!inode))
> >>>> return failed_creating(dentry);
> >>>>
> >>>> - inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
> >>>> + if(!parent)
> >>>> + parent = debugfs_mount->mnt_root;
> >>>> + inode->i_mode = S_IFDIR | (d_inode(parent)->i_mode
> >>>> + & (S_IRWXU | S_IRWXG));
> >>>> inode->i_op = &simple_dir_inode_operations;
> >>>> inode->i_fop = &simple_dir_operations;
> >>>>
> >>>
> >>> This looks ok, but is it going to change the permissions of existing
> >>> stuff in ways that might breaks things, right?
> >>
> >> Right, but debugfs is usually mounted on /sys/kernel/debug with
> >> permissions rwx to root owner. It can be changed after the mount, of
> >> course.
> >> Unless this is done, the directory permissions for /sys/kernel/debug
> >> will stop any descend regardless of the subdirectory permissions.
> >>
> >>>
> >>> Have you done a before/after comparison?
> >>
> >> I have tested this patch on my Linux 4.17.0rc2 kernel on s390.
> >> That worked well, I have not tested other systems.
> >
> > What do you mean by "worked well"? What were the full tree differences
> > between before and after? You should be able to get this by using:
> > tree -dp /sys/kernel/debug/
> > and then doing a diff on the two files.
> >
> > thanks,
> >
> > greg k-h
> >
>
> Ok, this is the tree output
>
> Before the patch:
> root@s8360047 ~]# tree -dp -L 1 /sys/kernel/debug/
> /sys/kernel/debug/
> ├── [drwxr-xr-x] bdi
> ├── [drwxr-xr-x] block
> ├── [drwxr-xr-x] dasd
> ├── [drwxr-xr-x] device_component
> ├── [drwxr-xr-x] extfrag
> ├── [drwxr-xr-x] hid
> ├── [drwxr-xr-x] kprobes
> ├── [drwxr-xr-x] kvm
> ├── [drwxr-xr-x] memblock
> ├── [drwxr-xr-x] pm_qos
> ├── [drwxr-xr-x] qdio
> ├── [drwxr-xr-x] s390
> ├── [drwxr-xr-x] s390dbf
> └── [drwx------] tracing
>
> 14 directories
>
> After the patch:
> [root@s8360047 ~]# tree -dp -L 1 /sys/kernel/debug/
> sys/kernel/debug/
> ├── [drwx------] bdi
> ├── [drwx------] block
> ├── [drwx------] dasd
> ├── [drwx------] device_component
> ├── [drwx------] extfrag
> ├── [drwx------] hid
> ├── [drwx------] kprobes
> ├── [drwx------] kvm
> ├── [drwx------] memblock
> ├── [drwx------] pm_qos
> ├── [drwx------] qdio
> ├── [drwx------] s390
> ├── [drwx------] s390dbf
> └── [drwx------] tracing
>
> 14 directories
> [root@s8360047 ~]#
>
> I attached the diff of the full tree before and after the patch.
"diff -u" is your friend, this isn't the 1990's anymore :)
Anyway, why just look at the root directory here? Your patch changes
more than just that, right?
Also, always run checkpatch.pl on your patches before a grumpy
maintainer tells you to run checkpatch.pl...
thanks,
greg k-h
