* [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
[not found] <20190622000358.19895-1-matthewgarrett@google.com>
@ 2019-06-22 0:03 ` Matthew Garrett
2019-06-23 0:14 ` Kees Cook
2019-06-25 15:00 ` Ard Biesheuvel
0 siblings, 2 replies; 3+ messages in thread
From: Matthew Garrett @ 2019-06-22 0:03 UTC (permalink / raw)
To: jmorris
Cc: linux-security-module, linux-kernel, linux-api, Matthew Garrett,
Matthew Garrett, Ard Biesheuvel, linux-efi
efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
EFI variable, which gives arbitrary code execution in ring 0. Prevent
that when the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
---
drivers/firmware/efi/efi.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 55b77c576c42..9f92a013ab27 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -31,6 +31,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/security.h>
#include <asm/early_ioremap.h>
@@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
static int __init efivar_ssdt_setup(char *str)
{
+ int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+
+ if (ret)
+ return ret;
+
if (strlen(str) < sizeof(efivar_ssdt))
memcpy(efivar_ssdt, str, strlen(str));
else
--
2.22.0.410.gd8fdbe21b5-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
2019-06-22 0:03 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Matthew Garrett
@ 2019-06-23 0:14 ` Kees Cook
2019-06-25 15:00 ` Ard Biesheuvel
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2019-06-23 0:14 UTC (permalink / raw)
To: Matthew Garrett
Cc: jmorris, linux-security-module, linux-kernel, linux-api,
Matthew Garrett, Ard Biesheuvel, linux-efi
On Fri, Jun 21, 2019 at 05:03:57PM -0700, Matthew Garrett wrote:
> efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
> EFI variable, which gives arbitrary code execution in ring 0. Prevent
> that when the kernel is locked down.
>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: linux-efi@vger.kernel.org
> ---
> drivers/firmware/efi/efi.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 55b77c576c42..9f92a013ab27 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -31,6 +31,7 @@
> #include <linux/acpi.h>
> #include <linux/ucs2_string.h>
> #include <linux/memblock.h>
> +#include <linux/security.h>
>
> #include <asm/early_ioremap.h>
>
> @@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
> static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
> static int __init efivar_ssdt_setup(char *str)
> {
> + int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
> +
> + if (ret)
> + return ret;
> +
> if (strlen(str) < sizeof(efivar_ssdt))
> memcpy(efivar_ssdt, str, strlen(str));
> else
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
2019-06-22 0:03 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Matthew Garrett
2019-06-23 0:14 ` Kees Cook
@ 2019-06-25 15:00 ` Ard Biesheuvel
1 sibling, 0 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2019-06-25 15:00 UTC (permalink / raw)
To: Matthew Garrett
Cc: James Morris, linux-security-module, Linux Kernel Mailing List,
linux-api, Matthew Garrett, linux-efi
On Sat, 22 Jun 2019 at 02:05, Matthew Garrett <matthewgarrett@google.com> wrote:
>
> efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
> EFI variable, which gives arbitrary code execution in ring 0. Prevent
> that when the kernel is locked down.
>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: linux-efi@vger.kernel.org
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> drivers/firmware/efi/efi.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 55b77c576c42..9f92a013ab27 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -31,6 +31,7 @@
> #include <linux/acpi.h>
> #include <linux/ucs2_string.h>
> #include <linux/memblock.h>
> +#include <linux/security.h>
>
> #include <asm/early_ioremap.h>
>
> @@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
> static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
> static int __init efivar_ssdt_setup(char *str)
> {
> + int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
> +
> + if (ret)
> + return ret;
> +
> if (strlen(str) < sizeof(efivar_ssdt))
> memcpy(efivar_ssdt, str, strlen(str));
> else
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-06-22 0:03 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Matthew Garrett
2019-06-23 0:14 ` Kees Cook
2019-06-25 15:00 ` Ard Biesheuvel
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