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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     Alexey Gladkov <gladkov.alexey@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        Linux API <linux-api@vger.kernel.org>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Linux Security Module <linux-security-module@vger.kernel.org>,
        Akinobu Mita <akinobu.mita@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Alexey Gladkov <legion@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Daniel Micay <danielmicay@gmail.com>,
        Djalal Harouni <tixxdz@gmail.com>,
        "Dmitry V . Levin" <ldv@altlinux.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Jeff Layton <jlayton@poochiereds.net>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>
References: <20200327172331.418878-1-gladkov.alexey@gmail.com>
        <20200327172331.418878-3-gladkov.alexey@gmail.com>
Date:   Thu, 02 Apr 2020 10:31:48 -0500
In-Reply-To: <20200327172331.418878-3-gladkov.alexey@gmail.com> (Alexey
        Gladkov's message of "Fri, 27 Mar 2020 18:23:24 +0100")
Message-ID: <87eet5lx97.fsf@x220.int.ebiederm.org>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)
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Subject: Re: [PATCH v10 2/9] proc: allow to mount many instances of proc in one pid namespace
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
> index 40a7982b7285..5920a4ecd71b 100644
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -27,6 +27,17 @@ struct proc_ops {
>  	unsigned long (*proc_get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
>  };
>  
> +struct proc_fs_info {
> +	struct pid_namespace *pid_ns;
> +	struct dentry *proc_self;        /* For /proc/self */
> +	struct dentry *proc_thread_self; /* For /proc/thread-self */
> +};

Minor nit.

I have not seen a patch where you remove proc_self and proc_thread_self
from struct pid_namepace.

Ideally it would have been in this patch.  But as it won't break
anyone's bisection can you please have a follow up patch that removes
those fields?

Thank you,
Eric


> +
> +static inline struct proc_fs_info *proc_sb_info(struct super_block *sb)
> +{
> +	return sb->s_fs_info;
> +}
> +
>  #ifdef CONFIG_PROC_FS
>  
>  typedef int (*proc_write_t)(struct file *, char *, size_t);
> @@ -161,6 +172,7 @@ int open_related_ns(struct ns_common *ns,
>  /* get the associated pid namespace for a file in procfs */
>  static inline struct pid_namespace *proc_pid_ns(const struct inode *inode)
>  {
> +	return proc_sb_info(inode->i_sb)->pid_ns;
>  	return inode->i_sb->s_fs_info;
>  }