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From: Casey Schaufler <casey@schaufler-ca.com>
To: casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: casey@schaufler-ca.com, keescook@chromium.org,
	john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
	paul@paul-moore.com, sds@tycho.nsa.gov
Subject: [PATCH v10 20/25] LSM: Verify LSM display sanity in binder
Date: Thu, 24 Oct 2019 13:52:23 -0700	[thread overview]
Message-ID: <20191024205228.6922-21-casey@schaufler-ca.com> (raw)
In-Reply-To: <20191024205228.6922-1-casey@schaufler-ca.com>

Verify that the tasks on the ends of a binder transaction
use the same "display" security module. This prevents confusion
of security "contexts".

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 30b0a04f14a2..ebbe7fac48d8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -706,9 +706,38 @@ 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 transacton 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);
 }
 
-- 
2.20.1


  parent reply	other threads:[~2019-10-24 20:54 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 20:52 [PATCH v10 00/25] LSM: Module stacking for AppArmor Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 01/25] LSM: Infrastructure management of the sock security Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 02/25] LSM: Create and manage the lsmblob data structure Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 03/25] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 04/25] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 05/25] net: Prepare UDS for security module stacking Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 06/25] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 07/25] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 08/25] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 09/25] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 10/25] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 11/25] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 12/25] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 13/25] LSM: Specify which LSM to display Casey Schaufler
2019-10-28 15:25   ` Stephen Smalley
2019-10-29 14:44   ` Simon McVittie
2019-10-29 15:44     ` Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 14/25] LSM: Ensure the correct LSM context releaser Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 15/25] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 16/25] LSM: Use lsmcontext in security_dentry_init_security Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 17/25] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 18/25] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 19/25] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2019-10-24 20:52 ` Casey Schaufler [this message]
2019-10-24 20:52 ` [PATCH v10 21/25] Audit: Add subj_LSM fields when necessary Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 22/25] Audit: Include object data for all security modules Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 23/25] NET: Add SO_PEERCONTEXT for multiple LSMs Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 24/25] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2019-10-24 20:52 ` [PATCH v10 25/25] AppArmor: Remove the exclusive flag Casey Schaufler
2019-10-29 14:53 ` [PATCH v10 00/25] LSM: Module stacking for AppArmor Stephen Smalley
2019-10-29 15:51   ` Casey Schaufler
2019-11-06 10:40     ` James Morris
2019-11-06 16:11       ` Casey Schaufler
2019-11-12 23:59 Casey Schaufler
2019-11-13  0:00 ` [PATCH v10 20/25] LSM: Verify LSM display sanity in binder Casey Schaufler

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