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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, linux-audit@redhat.com,
	keescook@chromium.org, john.johansen@canonical.com,
	penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com,
	sds@tycho.nsa.gov, linux-kernel@vger.kernel.org
Subject: [PATCH v23 18/23] LSM: Verify LSM display sanity in binder
Date: Fri, 20 Nov 2020 12:15:02 -0800	[thread overview]
Message-ID: <20201120201507.11993-19-casey@schaufler-ca.com> (raw)
In-Reply-To: <20201120201507.11993-1-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".

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Paul Moore <paul@paul-moore.com>
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 31c983a252b9..8803347424d4 100644
--- a/security/security.c
+++ b/security/security.c
@@ -791,9 +791,38 @@ 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_ilsm = lsm_task_ilsm(from);
+	int to_ilsm = lsm_task_ilsm(to);
+
+	/*
+	 * If the ilsm 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_ilsm == LSMBLOB_INVALID)
+		from_ilsm = 0;
+	if (to_ilsm == LSMBLOB_INVALID)
+		to_ilsm = 0;
+	if (from_ilsm != to_ilsm)
+		return -EINVAL;
+
 	return call_int_hook(binder_transaction, 0, from, to);
 }
 
-- 
2.24.1


WARNING: multiple messages have this Message-ID (diff)
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: john.johansen@canonical.com, linux-kernel@vger.kernel.org,
	linux-audit@redhat.com, sds@tycho.nsa.gov
Subject: [PATCH v23 18/23] LSM: Verify LSM display sanity in binder
Date: Fri, 20 Nov 2020 12:15:02 -0800	[thread overview]
Message-ID: <20201120201507.11993-19-casey@schaufler-ca.com> (raw)
In-Reply-To: <20201120201507.11993-1-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".

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Paul Moore <paul@paul-moore.com>
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 31c983a252b9..8803347424d4 100644
--- a/security/security.c
+++ b/security/security.c
@@ -791,9 +791,38 @@ 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_ilsm = lsm_task_ilsm(from);
+	int to_ilsm = lsm_task_ilsm(to);
+
+	/*
+	 * If the ilsm 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_ilsm == LSMBLOB_INVALID)
+		from_ilsm = 0;
+	if (to_ilsm == LSMBLOB_INVALID)
+		to_ilsm = 0;
+	if (from_ilsm != to_ilsm)
+		return -EINVAL;
+
 	return call_int_hook(binder_transaction, 0, from, to);
 }
 
-- 
2.24.1

--
Linux-audit mailing list
Linux-audit@redhat.com
https://www.redhat.com/mailman/listinfo/linux-audit


  parent reply	other threads:[~2020-11-20 20:35 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20201120201507.11993-1-casey.ref@schaufler-ca.com>
2020-11-20 20:14 ` [PATCH v22 00/23] LSM: Module stacking for AppArmor Casey Schaufler
2020-11-20 20:14   ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 01/23] LSM: Infrastructure management of the sock security Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 02/23] LSM: Create and manage the lsmblob data structure Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-12-28 17:54     ` Mimi Zohar
2020-12-28 17:54       ` Mimi Zohar
2020-12-28 19:22       ` Casey Schaufler
2020-12-28 19:22         ` Casey Schaufler
2020-12-28 19:43         ` Mimi Zohar
2020-12-28 19:43           ` Mimi Zohar
2020-12-28 19:24     ` Mimi Zohar
2020-12-28 19:24       ` Mimi Zohar
2020-12-28 20:06       ` Casey Schaufler
2020-12-28 20:06         ` Casey Schaufler
2020-12-28 22:14         ` Mimi Zohar
2020-12-28 22:14           ` Mimi Zohar
2020-12-28 23:20           ` Casey Schaufler
2020-12-28 23:20             ` Casey Schaufler
2020-12-29  1:53             ` Mimi Zohar
2020-12-29  1:53               ` Mimi Zohar
2020-12-29 13:53               ` Mimi Zohar
2020-12-29 13:53                 ` Mimi Zohar
2020-12-29 18:46               ` Casey Schaufler
2020-12-29 18:46                 ` Casey Schaufler
2020-12-29 19:16                 ` Mimi Zohar
2020-12-29 19:16                   ` Mimi Zohar
2020-11-20 20:14   ` [PATCH v23 03/23] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 04/23] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 05/23] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 06/23] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 07/23] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 08/23] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 09/23] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 10/23] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 11/23] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 12/23] LSM: Specify which LSM to display Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 13/23] LSM: Ensure the correct LSM context releaser Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 14/23] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:14   ` [PATCH v23 15/23] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2020-11-20 20:14     ` Casey Schaufler
2020-11-20 20:15   ` [PATCH v23 16/23] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 20:15   ` [PATCH v23 17/23] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 20:15   ` Casey Schaufler [this message]
2020-11-20 20:15     ` [PATCH v23 18/23] LSM: Verify LSM display sanity in binder Casey Schaufler
2020-11-20 20:15   ` [PATCH v23 19/23] audit: add support for non-syscall auxiliary records Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 23:06     ` kernel test robot
2020-11-20 23:06       ` kernel test robot
2020-11-20 23:06       ` kernel test robot
2020-11-21  0:36     ` kernel test robot
2020-11-21  0:36       ` kernel test robot
2020-11-21  7:36     ` kernel test robot
2020-11-21  7:36       ` kernel test robot
2020-11-21  7:36       ` kernel test robot
2020-11-20 20:15   ` [PATCH v23 20/23] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 22:51     ` kernel test robot
2020-11-20 22:51       ` kernel test robot
2020-11-20 22:51       ` kernel test robot
2020-11-21  0:02     ` kernel test robot
2020-11-21  0:02       ` kernel test robot
2020-11-21  0:02       ` kernel test robot
2020-11-20 20:15   ` [PATCH v23 21/23] Audit: Add a new record for multiple object " Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 20:15   ` [PATCH v23 22/23] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler
2020-11-20 20:15   ` [PATCH v23 23/23] AppArmor: Remove the exclusive flag Casey Schaufler
2020-11-20 20:15     ` Casey Schaufler

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