linux-kernel - [PATCH 08/12] asus-wmi: Restrict debugfs interface

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Message-Id: <1363642353-30749-8-git-send-email-matthew.garrett@nebula.com>
Date:	Mon, 18 Mar 2013 17:32:29 -0400
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
	kexec@...ts.infradead.org, linux-pci@...r.kernel.org,
	Matthew Garrett <matthew.garrett@...ula.com>
Subject: [PATCH 08/12] asus-wmi: Restrict debugfs interface

We have no way of validating what all of the Asus WMI methods do on a
given machine, and there's a risk that some will allow hardware state to
be manipulated in such a way that arbitrary code can be executed in the
kernel. Add a capability check to prevent that.

Signed-off-by: Matthew Garrett <matthew.garrett@...ula.com>
---
 drivers/platform/x86/asus-wmi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index c11b242..6d5f88f 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1617,6 +1617,9 @@ static int show_dsts(struct seq_file *m, void *data)
 	int err;
 	u32 retval = -1;
 
+	if (!capable(CAP_COMPROMISE_KERNEL))
+		return -EPERM;
+
 	err = asus_wmi_get_devstate(asus, asus->debug.dev_id, &retval);
 
 	if (err < 0)
@@ -1633,6 +1636,9 @@ static int show_devs(struct seq_file *m, void *data)
 	int err;
 	u32 retval = -1;
 
+	if (!capable(CAP_COMPROMISE_KERNEL))
+		return -EPERM;
+
 	err = asus_wmi_set_devstate(asus->debug.dev_id, asus->debug.ctrl_param,
 				    &retval);
 
@@ -1657,6 +1663,9 @@ static int show_call(struct seq_file *m, void *data)
 	union acpi_object *obj;
 	acpi_status status;
 
+	if (!capable(CAP_COMPROMISE_KERNEL))
+		return -EPERM;
+
 	status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
 				     1, asus->debug.method_id,
 				     &input, &output);
-- 
1.8.1.2

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