linux-kernel - Re: [PATCH] KEYS: The request_key() syscall should link an existing key to the dest keyring

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Message-ID: <14312.1272466729@redhat.com>
Date:	Wed, 28 Apr 2010 15:58:49 +0100
From:	David Howells <dhowells@...hat.com>
To:	Vegard Nossum <vegard.nossum@...il.com>
Cc:	dhowells@...hat.com, torvalds@...l.org, akpm@...ux-foundation.org,
	keyrings@...ux-nfs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KEYS: The request_key() syscall should link an existing key to the dest keyring

Vegard Nossum <vegard.nossum@...il.com> wrote:

> 1. Is it correct to return -EINPROGRESS in this case?

Yes - it prevents construct_key_and_link() from going on to call
construct_key().  The key in question is returned in *_key.

However, I don't think I handle other errors coming back from
construct_alloc_key() correctly.

> 2. (Why) Shouldn't the return value of __key_link() be checked?

It should.  In fact, I should probably precheck and preallocate the keyring to
make sure I don't get errors after allocating the new key.

> 3. In __key_link(), shouldn't rcu_dereference() be used when accessing
> keyring->payload.subscriptions?

No.  We have to hold a write lock on the keyring semaphore if we're going to
call __key_link() to add something to it.

We should, however, call rcu_dereference_protected().

You should find a patch for this in your inbox.

David
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