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From: John Johansen <john.johansen@canonical.com>
To: Casey Schaufler <casey@schaufler-ca.com>,
	casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: linux-audit@redhat.com, sds@tycho.nsa.gov
Subject: Re: [PATCH v19 19/23] LSM: Verify LSM display sanity in binder
Date: Thu, 30 Jul 2020 01:40:52 -0700
Message-ID: <8489396e-01a9-6fce-2afa-8a26fd3e3a3a@canonical.com> (raw)
In-Reply-To: <20200724203226.16374-20-casey@schaufler-ca.com>

On 7/24/20 1:32 PM, Casey Schaufler wrote:
> Verify that the tasks on the ends of a binder transaction
> use the same "display" security module. This prevents confusion
> of security "contexts".
> 

Reviewed-by: John Johansen <john.johansen@canonical.com>

> Reviewed-by: Kees Cook <keescook@chromium.org>
> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>  security/security.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/security/security.c b/security/security.c
> index ddbaf2073b02..95b48721fb17 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -788,9 +788,38 @@ int security_binder_set_context_mgr(struct task_struct *mgr)
>  	return call_int_hook(binder_set_context_mgr, 0, mgr);
>  }
>  
> +/**
> + * security_binder_transaction - Binder driver transaction check
> + * @from: source of the transaction
> + * @to: destination of the transaction
> + *
> + * Verify that the tasks have the same LSM "display", then
> + * call the security module hooks.
> + *
> + * Returns -EINVAL if the displays don't match, or the
> + * result of the security module checks.
> + */
>  int security_binder_transaction(struct task_struct *from,
>  				struct task_struct *to)
>  {
> +	int from_display = lsm_task_display(from);
> +	int to_display = lsm_task_display(to);
> +
> +	/*
> +	 * If the display is LSMBLOB_INVALID the first module that has
> +	 * an entry is used. This will be in the 0 slot.
> +	 *
> +	 * This is currently only required if the server has requested
> +	 * peer contexts, but it would be unwieldly to have too much of
> +	 * the binder driver detail here.
> +	 */
> +	if (from_display == LSMBLOB_INVALID)
> +		from_display = 0;
> +	if (to_display == LSMBLOB_INVALID)
> +		to_display = 0;
> +	if (from_display != to_display)
> +		return -EINVAL;
> +
>  	return call_int_hook(binder_transaction, 0, from, to);
>  }
>  
> 

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Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200724203226.16374-1-casey.ref@schaufler-ca.com>
2020-07-24 20:32 ` [PATCH v19 00/23] LSM: Module stacking for AppArmor Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 01/23] LSM: Infrastructure management of the sock security Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 02/23] LSM: Create and manage the lsmblob data structure Casey Schaufler
2020-07-27 16:12     ` Stephen Smalley
2020-07-27 21:04       ` Casey Schaufler
2020-07-28 19:50     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 03/23] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 04/23] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2020-07-28 10:34     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 05/23] net: Prepare UDS for security module stacking Casey Schaufler
2020-07-28 10:57     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 06/23] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2020-07-28 11:11     ` John Johansen
2020-07-28 23:41       ` Casey Schaufler
2020-07-29  0:30         ` John Johansen
2020-07-24 20:32   ` [PATCH v19 07/23] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 08/23] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 09/23] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 10/23] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 11/23] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 12/23] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 13/23] LSM: Specify which LSM to display Casey Schaufler
2020-07-27 20:36     ` James Morris
2020-07-27 20:40       ` John Johansen
2020-07-28 18:29     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 14/23] LSM: Ensure the correct LSM context releaser Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 15/23] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2020-07-28 20:13     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 16/23] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2020-07-28 20:28     ` John Johansen
2020-07-24 20:32   ` [PATCH v19 17/23] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2020-07-27 20:37     ` James Morris
2020-07-24 20:32   ` [PATCH v19 18/23] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 19/23] LSM: Verify LSM display sanity in binder Casey Schaufler
2020-07-30  8:40     ` John Johansen [this message]
2020-07-24 20:32   ` [PATCH v19 20/23] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2020-07-27 19:04     ` Stephen Smalley
2020-07-24 20:32   ` [PATCH v19 21/23] Audit: Add a new record for multiple object " Casey Schaufler
2020-07-27 20:40     ` James Morris
2020-07-24 20:32   ` [PATCH v19 22/23] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2020-07-30 10:03     ` John Johansen
2020-07-30 20:44       ` Casey Schaufler
2020-07-30 20:57         ` John Johansen
2020-07-30 22:22           ` Casey Schaufler
2020-07-24 20:32   ` [PATCH v19 23/23] AppArmor: Remove the exclusive flag Casey Schaufler
2020-07-30  9:23     ` John Johansen

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