[PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC

[David Laight]

From: Kees Cook
> Sent: 14 May 2020 04:05
> On Wed, May 13, 2020 at 04:27:39PM -0700, Kees Cook wrote:
> > Like, couldn't just the entire thing just be:
> >
> > diff --git a/fs/namei.c b/fs/namei.c
> > index a320371899cf..0ab18e19f5da 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -2849,6 +2849,13 @@ static int may_open(const struct path *path, int acc_mode, int flag)
> >  		break;
> >  	}
> >
> > +	if (unlikely(mask & MAY_OPENEXEC)) {
> > +		if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_MOUNT &&
> > +		    path_noexec(path))
> > +			return -EACCES;
> > +		if (sysctl_omayexec_enforce & OMAYEXEC_ENFORCE_FILE)
> > +			acc_mode |= MAY_EXEC;
> > +	}
> >  	error = inode_permission(inode, MAY_OPEN | acc_mode);
> >  	if (error)
> >  		return error;
> >
> 
> FYI, I've confirmed this now. Effectively with patch 2 dropped, patch 3
> reduced to this plus the Kconfig and sysctl changes, the self tests
> pass.
> 
> I think this makes things much cleaner and correct.

And a summary of that would be right for the 0/n patch email.

	David

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