linux-kernel - [PATCH V37 17/29] Prohibit PCMCIA CIS storage when the kernel is locked down

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Message-Id: <20190731221617.234725-18-matthewgarrett@google.com>
Date:   Wed, 31 Jul 2019 15:16:05 -0700
From:   Matthew Garrett <matthewgarrett@...gle.com>
To:     jmorris@...ei.org
Cc:     linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        David Howells <dhowells@...hat.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Matthew Garrett <mjg59@...gle.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH V37 17/29] Prohibit PCMCIA CIS storage when the kernel is
 locked down

From: David Howells <dhowells@...hat.com>

Prohibit replacement of the PCMCIA Card Information Structure when the
kernel is locked down.

Suggested-by: Dominik Brodowski <linux@...inikbrodowski.net>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Matthew Garrett <mjg59@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
 drivers/pcmcia/cistpl.c      | 5 +++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/drivers/pcmcia/cistpl.c b/drivers/pcmcia/cistpl.c
index abd029945cc8..629359fe3513 100644
--- a/drivers/pcmcia/cistpl.c
+++ b/drivers/pcmcia/cistpl.c
@@ -21,6 +21,7 @@
 #include <linux/pci.h>
 #include <linux/ioport.h>
 #include <linux/io.h>
+#include <linux/security.h>
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
 
@@ -1575,6 +1576,10 @@ static ssize_t pccard_store_cis(struct file *filp, struct kobject *kobj,
 	struct pcmcia_socket *s;
 	int error;
 
+	error = security_locked_down(LOCKDOWN_PCMCIA_CIS);
+	if (error)
+		return error;
+
 	s = to_socket(container_of(kobj, struct device, kobj));
 
 	if (off)
diff --git a/include/linux/security.h b/include/linux/security.h
index 1c32522b3c5a..3773ad09b831 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -111,6 +111,7 @@ enum lockdown_reason {
 	LOCKDOWN_IOPORT,
 	LOCKDOWN_MSR,
 	LOCKDOWN_ACPI_TABLES,
+	LOCKDOWN_PCMCIA_CIS,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index ecb51b1a5c03..22482e1b9a77 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -26,6 +26,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_IOPORT] = "raw io port access",
 	[LOCKDOWN_MSR] = "raw MSR access",
 	[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
+	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.770.g0f2c4a37fd-goog