linux-kernel - Re: [PATCH] keyrings: Allow searching the user session keyring

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Date:	Thu, 17 Mar 2016 10:04:49 -0700
From:	Gwendal Grignou <gwendal@...omium.org>
To:	Gwendal Grignou <gwendal@...omium.org>, dhowells@...hat.com,
	james.l.morris@...cle.com, serge@...lyn.com
Cc:	keyrings@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	"Theodore Ts'o" <tytso@....edu>
Subject: Re: [PATCH] keyrings: Allow searching the user session keyring

Resent to a larger audience.

On Thu, Mar 10, 2016 at 2:20 PM, Gwendal Grignou <gwendal@...omium.org> wrote:
> Currently, if a session keyring exists, we are not searching in the
> user session or user keyrings.
>
> This is a problem when a session keyring exists and we want to use
> ecryptfs, who adds the needed key only in the user keyring.
>
> TEST=Without this change, mounting an ecryptfs "partition" fails when a
> session keyring exists:
> ...
> [ 2686.047522] Could not find key with description: [dd6f92bd8660b36c]
> ...
> Although the key exits:
> keyctl show @us
> Keyring
>  549666721 --alswrv      0 65534  keyring: _uid_ses.0
>  346719914 --alswrv      0 65534   \_ keyring: _uid.0
>  235623693 --alswrv      0     0       \_ user: dd6f92bd8660b36c
>  747773852 --alswrv      0     0       \_ user: 7025717e50fd74a2
> With this change, ecryptfs can see the keys it needs.
>
> Note that 'keyctl show' still only shows the session keyring by default.
> We need to specify 'keyctl show @us' to see the user session keyring
> when the session keyring exits.
>
> Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
> ---
>  security/keys/process_keys.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
> index e6d50172..a77d66e 100644
> --- a/security/keys/process_keys.c
> +++ b/security/keys/process_keys.c
> @@ -395,8 +395,8 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
>                         break;
>                 }
>         }
> -       /* or search the user-session keyring */
> -       else if (ctx->cred->user->session_keyring) {
> +       /* finally search the user-session keyring */
> +       if (ctx->cred->user->session_keyring) {
>                 key_ref = keyring_search_aux(
>                         make_key_ref(ctx->cred->user->session_keyring, 1),
>                         ctx);
> --
> 2.7.0.rc3.207.g0ac5344
>