linux-kernel - Re: [PATCH 2/4] autofs4 - track uid and gid of last mount requester

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Message-Id: <20080807134650.a6a51f7d.akpm@linux-foundation.org>
Date:	Thu, 7 Aug 2008 13:46:50 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ian Kent <raven@...maw.net>
Cc:	autofs@...ux.kernel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, containers@...ts.osdl.org
Subject: Re: [PATCH 2/4] autofs4 - track uid and gid of last mount requester

On Thu, 07 Aug 2008 19:40:14 +0800
Ian Kent <raven@...maw.net> wrote:

> Patch to track the uid and gid of the last process to request a mount
> for on an autofs dentry.

pet peeve: changelog should not tell the reader that this is a "patch".
Because when someone is reading the changelog in the git repository,
they hopefully already know that.

> Signed-off-by: Ian Kent <raven@...maw.net>
> 
> ---
> 
>  fs/autofs4/autofs_i.h |    3 +++
>  fs/autofs4/inode.c    |    2 ++
>  fs/autofs4/waitq.c    |   34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 39 insertions(+), 0 deletions(-)
> 
> 
> diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
> index ea024d8..fa76d18 100644
> --- a/fs/autofs4/autofs_i.h
> +++ b/fs/autofs4/autofs_i.h
> @@ -63,6 +63,9 @@ struct autofs_info {
>  	unsigned long last_used;
>  	atomic_t count;
>  
> +	uid_t uid;
> +	gid_t gid;
> +
>  	mode_t	mode;
>  	size_t	size;
>  
> diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
> index 9ca2d07..9408507 100644
> --- a/fs/autofs4/inode.c
> +++ b/fs/autofs4/inode.c
> @@ -53,6 +53,8 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
>  		atomic_set(&ino->count, 0);
>  	}
>  
> +	ino->uid = 0;
> +	ino->gid = 0;
>  	ino->mode = mode;
>  	ino->last_used = jiffies;
>  
> diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> index 6d87bb1..7c60c0b 100644
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -457,6 +457,40 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
>  
>  	status = wq->status;
>  
> +	/*
> +	 * For direct and offset mounts we need to track the requestrer

typo which I'll fix.

> +	 * uid and gid in the dentry info struct. This is so it can be
> +	 * supplied, on request, by the misc device ioctl interface.
> +	 * This is needed during daemon resatart when reconnecting
> +	 * to existing, active, autofs mounts. The uid and gid (and
> +	 * related string values) may be used for macro substitution
> +	 * in autofs mount maps.
> +	 */
> +	if (!status) {
> +		struct autofs_info *ino;
> +		struct dentry *de = NULL;
> +
> +		/* direct mount or browsable map */
> +		ino = autofs4_dentry_ino(dentry);
> +		if (!ino) {
> +			/* If not lookup actual dentry used */
> +			de = d_lookup(dentry->d_parent, &dentry->d_name);
> +			if (de)
> +				ino = autofs4_dentry_ino(de);
> +		}
> +
> +		/* Set mount requester */
> +		if (ino) {
> +			spin_lock(&sbi->fs_lock);
> +			ino->uid = wq->uid;
> +			ino->gid = wq->gid;
> +			spin_unlock(&sbi->fs_lock);
> +		}
> +
> +		if (de)
> +			dput(de);
> +	}
> +

Please remind me again why autofs's use of current->uid and
current->gid is not busted in the presence of PID namespaces, where
these things are no longer system-wide unique?
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