Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1523872

[PATCH 03/16] efi: Disable secure boot if shim is in insecure mode

Show all headers | View raw

From: Josh Boyer <jwboyer@fedoraproject.org>

A user can manually tell the shim boot loader to disable validation of
images it loads.  When a user does this, it creates a UEFI variable called
MokSBState that does not have the runtime attribute set.  Given that the
user explicitly disabled validation, we can honor that and not enable
secure boot mode if that variable is set.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/x86/boot/compressed/eboot.c |   20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 17b376596c96..2729a3844673 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -540,8 +540,9 @@ static void setup_efi_pci(struct boot_params *params)
 
 static int get_secure_boot(void)
 {
-	u8 sb, setup;
+	u8 sb, setup, moksbstate;
 	unsigned long datasize = sizeof(sb);
+	u32 attr;
 	efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
 	efi_status_t status;
 
@@ -565,6 +566,23 @@ static int get_secure_boot(void)
 	if (setup == 1)
 		return 0;
 
+	/* See if a user has put shim into insecure_mode.  If so, and the variable
+	 * doesn't have the runtime attribute set, we might as well honor that.
+	 */
+	var_guid = EFI_SHIM_LOCK_GUID;
+	status = efi_early->call((unsigned long)sys_table->runtime->get_variable,
+				L"MokSBState", &var_guid, &attr, &datasize,
+				&moksbstate);
+
+	/* If it fails, we don't care why.  Default to secure */
+	if (status != EFI_SUCCESS)
+		return 1;
+
+	if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS)) {
+		if (moksbstate == 1)
+			return 0;
+	}
+
 	return 1;
 }
 

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 00/16] Kernel lockdown David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 15/16] acpi: Ignore acpi_rsdp kernel param when the kernel  has been locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
    Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-17 23:00 +0100
      Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Josh Boyer <jwboyer@fedoraproject.org> - 2016-11-18 13:00 +0100
        Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-18 13:20 +0100
      Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit David Howells <dhowells@redhat.com> - 2016-11-18 18:30 +0100
  [PATCH 07/16] kexec: Disable at runtime if the kernel is locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 08/16] Copy secure_boot flag in boot params across kexec  reboot David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 12/16] ACPI: Limit access to custom_method when the kernel  is locked down David Howells <dhowells@redhat.com> - 2016-11-16 22:50 +0100
  [PATCH 03/16] efi: Disable secure boot if shim is in insecure mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 04/16] efi: Lock down the kernel if booted in secure boot  mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 11/16] x86: Lock down IO port access when the kernel is  locked down David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  [PATCH 06/16] Add a sysrq option to exit secure boot mode David Howells <dhowells@redhat.com> - 2016-11-16 23:00 +0100
  Re: [PATCH 00/16] Kernel lockdown One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-11-16 23:30 +0100
    Re: [PATCH 00/16] Kernel lockdown Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-11-21 21:00 +0100
  Re: [PATCH 00/16] Kernel lockdown Justin Forbes <jmforbes@linuxtx.org> - 2016-11-16 23:30 +0100
  Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-22 07:30 +0100
    Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed David Howells <dhowells@redhat.com> - 2016-11-23 14:00 +0100
      Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-23 20:30 +0100
        Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed David Howells <dhowells@redhat.com> - 2016-11-24 18:40 +0100
          Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs  and dma changed Dominik Brodowski <linux@dominikbrodowski.net> - 2016-11-24 21:30 +0100

csiph-web