Messages in this thread | | | Subject | Re: [PATCH] inode: debugfs_create_dir uses mode permission from parent | From | Thomas-Mich Richter <> | Date | Fri, 27 Apr 2018 11:14:26 +0200 |
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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 <tmricht@linux.ibm.com> >> Cc: Greg Kroah-Hartman <gregkh@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.
-- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
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