Messages in this thread | | | Date | Wed, 5 Jan 2022 12:51:31 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] debugfs: lockdown: Allow reading debugfs files that are not world readable |
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On Tue, Jan 04, 2022 at 06:05:05PM +0100, Michal Suchanek wrote: > > When the kernel is locked down the kernel allows reading only debugfs > files with mode 444. Mode 400 is also valid but is not allowed. > > Make the 444 into a mask. > > Fixes: 5496197f9b08 ("debugfs: Restrict debugfs when the kernel is locked down") > Signed-off-by: Michal Suchanek <msuchanek@suse.de> > --- > fs/debugfs/file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-)
Why has it taken so long for anyone to notice this (2 years!)?
Is that because no one uses the lockdown mode and tries to read debugfs files?
> > diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c > index 7d162b0efbf0..950c63fa4d0b 100644 > --- a/fs/debugfs/file.c > +++ b/fs/debugfs/file.c > @@ -147,7 +147,7 @@ static int debugfs_locked_down(struct inode *inode, > struct file *filp, > const struct file_operations *real_fops) > { > - if ((inode->i_mode & 07777) == 0444 && > + if ((inode->i_mode & 07777 & ~0444) == 0 &&
You are now allowing more than just 0400, is that intentional?
I never understood why files that were 0666 were not able to be read here as well, why not allow that as well? What was magic about 0444 files?
thanks,
greg k-h
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