linux-kernel - Re: [PATCH 1/2] fs: anon_inodes: export anon_inode_getfile

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Message-ID: <CAHC9VhTBcCJ1TfvB-HbzrByroeqfFE-SF_REik9PDSdqmJbuYA@mail.gmail.com>
Date:   Wed, 19 May 2021 11:22:51 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>
Cc:     io-uring@...r.kernel.org, Pavel Emelyanov <xemul@...nvz.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        Lokesh Gidra <lokeshgidra@...gle.com>,
        Eric Biggers <ebiggers@...gle.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] fs: anon_inodes: export anon_inode_getfile_secure helper

On Wed, May 19, 2021 at 7:37 AM Kumar Kartikeya Dwivedi
<memxor@...il.com> wrote:
>
> This is the non-fd installing analogue of anon_inode_getfd_secure. In
> addition to allowing LSMs to attach policy to the distinct inode, this
> is also needed for checkpoint restore of an io_uring instance where a
> mapped region needs to mapped back to the io_uring fd by CRIU. This is
> currently not possible as all anon_inodes share a single inode.
>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
> ---
>  fs/anon_inodes.c            | 9 +++++++++
>  include/linux/anon_inodes.h | 4 ++++
>  2 files changed, 13 insertions(+)

[NOTE: dropping dancol@...gle as that email is bouncy]

> diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
> index a280156138ed..37032786b211 100644
> --- a/fs/anon_inodes.c
> +++ b/fs/anon_inodes.c
> @@ -148,6 +148,15 @@ struct file *anon_inode_getfile(const char *name,
>  }
>  EXPORT_SYMBOL_GPL(anon_inode_getfile);

This function should have a comment block at the top similar to
anon_inode_getfile(); in fact you can likely copy-n-paste the bulk of
it to use as a start.

If you don't want to bother respinning, I've got this exact patch
(+comments) in my patchset that I'll post later and I'm happy to
give/share credit if that is important to you.

> +struct file *anon_inode_getfile_secure(const char *name,
> +                                      const struct file_operations *fops,
> +                                      void *priv, int flags,
> +                                      const struct inode *context_inode)
> +{
> +       return __anon_inode_getfile(name, fops, priv, flags, context_inode, true);
> +}
> +EXPORT_SYMBOL_GPL(anon_inode_getfile_secure);

-- 
paul moore
www.paul-moore.com