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: keescook@chromium.org, john.johansen@canonical.com,
penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com,
sds@tycho.nsa.gov
Subject: [PATCH v11 20/25] LSM: Verify LSM display sanity in binder
Date: Wed, 13 Nov 2019 10:25:01 -0800 [thread overview]
Message-ID: <20191113182506.2580-4-casey@schaufler-ca.com> (raw)
In-Reply-To: <20191113182506.2580-1-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 101063b00aeb..0e8c61cceecd 100644
--- a/security/security.c
+++ b/security/security.c
@@ -738,9 +738,38 @@ 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
next prev parent reply other threads:[~2019-11-13 18:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191113182506.2580-1-casey.ref@schaufler-ca.com>
2019-11-13 18:24 ` [PATCH v11 00/25] LSM: Module stacking for AppArmor Casey Schaufler
2019-11-13 18:24 ` [PATCH v11 18/25] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2019-11-21 19:01 ` John Johansen
2019-11-21 20:36 ` James Morris
2019-11-13 18:25 ` [PATCH v11 19/25] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2019-11-21 19:02 ` John Johansen
2019-11-13 18:25 ` Casey Schaufler [this message]
2019-11-13 18:25 ` [PATCH v11 21/25] Audit: Add subj_LSM fields when necessary Casey Schaufler
2019-11-13 18:25 ` [PATCH v11 22/25] Audit: Include object data for all security modules Casey Schaufler
2019-11-13 18:25 ` [PATCH v11 23/25] NET: Add SO_PEERCONTEXT for multiple LSMs Casey Schaufler
2019-11-13 18:25 ` [PATCH v11 24/25] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2019-11-13 18:25 ` [PATCH v11 25/25] AppArmor: Remove the exclusive flag Casey Schaufler
2019-11-21 19:03 ` John Johansen
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