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From: Ian Kent <raven@themaw.net>
To: David Howells <dhowells@redhat.com>
Cc: Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Oleg Nesterov <onestero@redhat.com>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Benjamin Coddington <bcodding@redhat.com>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Jeff Layton <jeff.layton@primarydata.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [RFC PATCH 5 1/7] kmod - add workqueue service thread store
Date: Tue, 07 Apr 2015 08:42:35 +0800	[thread overview]
Message-ID: <1428367355.2705.6.camel@pluto.fritz.box> (raw)
In-Reply-To: <18729.1427978611@warthog.procyon.org.uk>

On Thu, 2015-04-02 at 13:43 +0100, David Howells wrote:
> Ian Kent <raven@themaw.net> wrote:
> 
> > +static struct umh_wq_entry *umh_wq_find_entry(int token)
> > +{
> > +	struct umh_wq_entry *this, *entry;
> > +	struct hlist_head *bucket;
> > +	unsigned int hash;
> > +
> > +	hash = hash_32((unsigned long) token, UMH_WQ_HASH_SHIFT);
> > +	bucket = &umh_wq_hash[hash];
> > +
> > +	entry = ERR_PTR(-ENOENT);
> > +	if (hlist_empty(bucket))
> > +		goto out;
> > +
> > +	hlist_for_each_entry(this, bucket, umh_wq_hlist) {
> > +		if (this->token == token) {
> > +			entry = this;
> > +			break;
> > +		}
> > +	}
> > +out:
> > +	return entry;
> > +}
> 
> Can "struct umh_wq_entry *" be used as the token?

Probably not, for example.

Couldn't a user set a different workqueue_struct and have it used for
execution. Not sure what that would get the user but it sounds like the
original reason we couldn't allow execution directly within the caller
environment.

> 
> David



  reply	other threads:[~2015-04-07  0:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-31  3:14 [RFC PATCH v5 0/7] Another attempt at contained helper execution Ian Kent
2015-03-31  3:14 ` [RFC PATCH 5 1/7] kmod - add workqueue service thread store Ian Kent
2015-03-31 11:21   ` Jeff Layton
2015-03-31 12:59     ` Ian Kent
2015-03-31  3:14 ` [RFC PATCH 5 2/7] kmod - teach usermodehelper to use service workqueues Ian Kent
2015-03-31  3:14 ` [RFC PATCH 5 3/7] nfsd - use service thread if not executing in init namespace Ian Kent
2015-03-31 13:14   ` J. Bruce Fields
2015-04-01  0:22     ` Ian Kent
2015-04-02 15:59       ` J. Bruce Fields
2015-03-31  3:15 ` [RFC PATCH 5 4/7] nfs - cache_lib " Ian Kent
2015-03-31  3:15 ` [RFC PATCH 5 5/7] nfs - objlayout " Ian Kent
2015-03-31  3:15 ` [RFC PATCH 5 6/7] KEYS - use correct memory allocation flag in call_usermodehelper_keys() Ian Kent
2015-03-31  3:15 ` [RFC PATCH 5 7/7] KEYS: exec request key within service thread of key creator Ian Kent
2015-04-02 12:43 ` [RFC PATCH 5 1/7] kmod - add workqueue service thread store David Howells
2015-04-07  0:42   ` Ian Kent [this message]
2015-04-02 12:58 ` [RFC PATCH 5 7/7] KEYS: exec request key within service thread of key creator David Howells
2015-04-07  0:54   ` Ian Kent
2015-04-02 13:00 ` [RFC PATCH 5 6/7] KEYS - use correct memory allocation flag in call_usermodehelper_keys() David Howells

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