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authorDavid Howells <dhowells@redhat.com>2019-08-20 03:17:56 +0300
committerJames Morris <jmorris@namei.org>2019-08-20 07:54:16 +0300
commit906357f77a077508d160e729f917c5f0a4304f25 (patch)
tree049ecdbb02af347886a383126722b6bc853503a6
parent20657f66ef52e5005369e4ef539d4cbf01eab10d (diff)
downloadlinux-906357f77a077508d160e729f917c5f0a4304f25.tar.xz
x86/mmiotrace: Lock down the testmmiotrace module
The testmmiotrace module shouldn't be permitted when the kernel is locked down as it can be used to arbitrarily read and write MMIO space. This is a runtime check rather than buildtime in order to allow configurations where the same kernel may be run in both locked down or permissive modes depending on local policy. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Howells <dhowells@redhat.com Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Kees Cook <keescook@chromium.org> cc: Thomas Gleixner <tglx@linutronix.de> cc: Steven Rostedt <rostedt@goodmis.org> cc: Ingo Molnar <mingo@kernel.org> cc: "H. Peter Anvin" <hpa@zytor.com> cc: x86@kernel.org Signed-off-by: James Morris <jmorris@namei.org>
-rw-r--r--arch/x86/mm/testmmiotrace.c5
-rw-r--r--include/linux/security.h1
-rw-r--r--security/lockdown/lockdown.c1
3 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 0881e1ff1e58..a8bd952e136d 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -8,6 +8,7 @@
#include <linux/module.h>
#include <linux/io.h>
#include <linux/mmiotrace.h>
+#include <linux/security.h>
static unsigned long mmio_address;
module_param_hw(mmio_address, ulong, iomem, 0);
@@ -115,6 +116,10 @@ static void do_test_bulk_ioremapping(void)
static int __init init(void)
{
unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
+ int ret = security_locked_down(LOCKDOWN_MMIOTRACE);
+
+ if (ret)
+ return ret;
if (mmio_address == 0) {
pr_err("you have to use the module argument mmio_address.\n");
diff --git a/include/linux/security.h b/include/linux/security.h
index 1a3404f9c060..d8db7ea4c4bf 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -114,6 +114,7 @@ enum lockdown_reason {
LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_TIOCSSERIAL,
LOCKDOWN_MODULE_PARAMETERS,
+ LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 0fa434294667..2eadbe0667e7 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
+ [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};