Re: [PATCH] mm/shmem.c: Add new seal to memfd: F_SEAL_WRITE_NONCREATOR

[Michael Tirado <mtirado418@gmail.com>]

On Thu, 16 Apr 2015 11:14:11 +0300
Konstantin Khlebnikov <koct9i@gmail.com> wrote:

> Keeping pointer to priviledged task is a bad idea.
> There is no easy way to drop it when task exits and this doesn't work
> for threads.
> I think it's better to keep pointer to priveledged struct file and
> drop it in method
> f_op->release() when task closes fd or exits. Server task could obtain second
> non-priveledged fd and struct file for that inode via
> open(/proc/../fd/), dup3(),
> openat() or something else and send it to read-only users.

Thank you, I was hoping someone would suggest a different authentication 
method, I will look into this idea.  What is the thread concern?  I have 
not run in to any problems yet while testing, but have been more focused 
on getting my user space memfd transport daemon up and running before I put 
it through the torture test.

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