From: Kees Cook <keescook@chromium.org>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: casey.schaufler@intel.com, jmorris@namei.org,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
paul@paul-moore.com, sds@tycho.nsa.gov, linux-audit@redhat.com
Subject: Re: [PATCH v16 19/23] LSM: Verify LSM display sanity in binder
Date: Tue, 7 Apr 2020 11:42:11 -0700 [thread overview]
Message-ID: <202004071142.C3250D5@keescook> (raw)
In-Reply-To: <20200407000159.43602-20-casey@schaufler-ca.com>
On Mon, Apr 06, 2020 at 05:01:55PM -0700, 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".
>
> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> security/security.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/security/security.c b/security/security.c
> index 84f33bd4990a..b7c2ed1eee42 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -769,9 +769,38 @@ 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);
> }
>
> --
> 2.24.1
>
--
Kees Cook
next prev parent reply other threads:[~2020-04-07 18:42 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200407000159.43602-1-casey.ref@schaufler-ca.com>
2020-04-07 0:01 ` [PATCH v16 00/23] LSM: Module stacking for AppArmor Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 01/23] LSM: Infrastructure management of the sock security Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 02/23] LSM: Create and manage the lsmblob data structure Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 03/23] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 04/23] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 05/23] net: Prepare UDS for security module stacking Casey Schaufler
2020-04-07 18:36 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 06/23] Use lsmblob in security_secctx_to_secid Casey Schaufler
2020-04-07 18:36 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 07/23] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 08/23] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 09/23] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 10/23] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 11/23] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 12/23] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 13/23] LSM: Specify which LSM to display Casey Schaufler
2020-04-07 18:40 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 14/23] LSM: Ensure the correct LSM context releaser Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 15/23] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2020-04-07 18:41 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 16/23] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2020-04-07 18:41 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 17/23] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 18/23] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2020-04-07 0:01 ` [PATCH v16 19/23] LSM: Verify LSM display sanity in binder Casey Schaufler
2020-04-07 18:42 ` Kees Cook [this message]
2020-04-07 0:01 ` [PATCH v16 20/23] Audit: Add a new record for multiple subject LSM attributes Casey Schaufler
2020-04-07 18:43 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 21/23] Audit: Add a new record for multiple object " Casey Schaufler
2020-04-07 18:43 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 22/23] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2020-04-07 18:47 ` Kees Cook
2020-04-07 0:01 ` [PATCH v16 23/23] AppArmor: Remove the exclusive flag Casey Schaufler
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