linux-kernel - Re: [RFC PATCH v1 1/2] mm/memfd: Add support for F_SEAL_FUTURE

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Message-ID: <Z1NjgK2wSUdeM525@google.com>
Date: Fri, 6 Dec 2024 12:50:08 -0800
From: Isaac Manjarres <isaacmanjarres@...gle.com>
To: Kalesh Singh <kaleshsingh@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Layton <jlayton@...nel.org>,
	Chuck Lever <chuck.lever@...cle.com>,
	Alexander Aring <alex.aring@...il.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
	Shuah Khan <shuah@...nel.org>, kernel-team@...roid.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	Suren Baghdasaryan <surenb@...gle.com>,
	John Stultz <jstultz@...gle.com>
Subject: Re: [RFC PATCH v1 1/2] mm/memfd: Add support for F_SEAL_FUTURE_EXEC
 to memfd

On Fri, Dec 06, 2024 at 09:49:35AM -0800, Kalesh Singh wrote:
> On Thu, Dec 5, 2024 at 5:09 PM Isaac J. Manjarres
> <isaacmanjarres@...gle.com> wrote:
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -375,6 +375,17 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
> >                 if (!file_mmap_ok(file, inode, pgoff, len))
> >                         return -EOVERFLOW;
> >
> > +               if (is_exec_sealed(seals)) {
> > +                       /* No new executable mappings if the file is exec sealed. */
> > +                       if (prot & PROT_EXEC)
> > +                               return -EACCES;
> 
> I think this should be -EPERM to be consistent with seal_check_write()
> and mmap(2) man page:
> 
> " EPERM The operation was prevented by a file seal; see fcntl(2)."
> 
> Thanks,
> Kalesh
> 

Thanks for catching that Kalesh! I agree and will fix this in v2 of the
series.

Thanks,
Isaac