Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761548Ab3IDAM6 (ORCPT ); Tue, 3 Sep 2013 20:12:58 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:33762 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754951Ab3IDAM5 (ORCPT ); Tue, 3 Sep 2013 20:12:57 -0400 From: Matthew Garrett To: linux-kernel@vger.kernel.org Cc: linux-efi@vger.kernel.org, keescook@chromium.org, hpa@zytor.com, Matthew Garrett Subject: [PATCH V3 11/11] Add option to automatically enforce module signatures when in Secure Boot mode Date: Tue, 3 Sep 2013 19:50:18 -0400 Message-Id: <1378252218-18798-12-git-send-email-matthew.garrett@nebula.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1378252218-18798-1-git-send-email-matthew.garrett@nebula.com> References: <1378252218-18798-1-git-send-email-matthew.garrett@nebula.com> X-SA-Do-Not-Run: Yes X-SA-Exim-Connect-IP: 2001:470:1f07:1371:6267:20ff:fec3:2318 X-SA-Exim-Mail-From: matthew.garrett@nebula.com X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5770 Lines: 185 UEFI Secure Boot provides a mechanism for ensuring that the firmware will only load signed bootloaders and kernels. Certain use cases may also require that all kernel modules also be signed. Add a configuration option that enforces this automatically when enabled. Signed-off-by: Matthew Garrett --- Documentation/x86/zero-page.txt | 2 ++ arch/x86/Kconfig | 10 ++++++++++ arch/x86/boot/compressed/eboot.c | 36 +++++++++++++++++++++++++++++++++++ arch/x86/include/uapi/asm/bootparam.h | 3 ++- arch/x86/kernel/setup.c | 6 ++++++ include/linux/module.h | 6 ++++++ kernel/module.c | 7 +++++++ 7 files changed, 69 insertions(+), 1 deletion(-) diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt index 199f453..ec38acf 100644 --- a/Documentation/x86/zero-page.txt +++ b/Documentation/x86/zero-page.txt @@ -30,6 +30,8 @@ Offset Proto Name Meaning 1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below) 1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer (below) +1EB/001 ALL kbd_status Numlock is enabled +1EC/001 ALL secure_boot Secure boot is enabled in the firmware 1EF/001 ALL sentinel Used to detect broken bootloaders 290/040 ALL edd_mbr_sig_buffer EDD MBR signatures 2D0/A00 ALL e820_map E820 memory map table diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b32ebf9..6a6c19b 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1581,6 +1581,16 @@ config EFI_STUB See Documentation/x86/efi-stub.txt for more information. +config EFI_SECURE_BOOT_SIG_ENFORCE + def_bool n + prompt "Force module signing when UEFI Secure Boot is enabled" + ---help--- + UEFI Secure Boot provides a mechanism for ensuring that the + firmware will only load signed bootloaders and kernels. Certain + use cases may also require that all kernel modules also be signed. + Say Y here to automatically enable module signature enforcement + when a system boots with UEFI Secure Boot enabled. + config SECCOMP def_bool y prompt "Enable seccomp to safely compute untrusted bytecode" diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index b7388a4..53bfe4f 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -12,6 +12,7 @@ #include #include #include +#include #undef memcpy /* Use memcpy from misc.c */ @@ -861,6 +862,37 @@ fail: return status; } +static int get_secure_boot(void) +{ + u8 sb, setup; + unsigned long datasize = sizeof(sb); + efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID; + efi_status_t status; + + status = efi_call_phys5(sys_table->runtime->get_variable, + L"SecureBoot", &var_guid, NULL, &datasize, &sb); + + if (status != EFI_SUCCESS) + return 0; + + if (sb == 0) + return 0; + + + status = efi_call_phys5(sys_table->runtime->get_variable, + L"SetupMode", &var_guid, NULL, &datasize, + &setup); + + if (status != EFI_SUCCESS) + return 0; + + if (setup == 1) + return 0; + + return 1; +} + + /* * Because the x86 boot code expects to be passed a boot_params we * need to create one ourselves (usually the bootloader would create @@ -1169,6 +1201,10 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table, if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) goto fail; + sanitize_boot_params(boot_params); + + boot_params->secure_boot = get_secure_boot(); + setup_graphics(boot_params); setup_efi_pci(boot_params); diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index c15ddaf..85d7685 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -131,7 +131,8 @@ struct boot_params { __u8 eddbuf_entries; /* 0x1e9 */ __u8 edd_mbr_sig_buf_entries; /* 0x1ea */ __u8 kbd_status; /* 0x1eb */ - __u8 _pad5[3]; /* 0x1ec */ + __u8 secure_boot; /* 0x1ec */ + __u8 _pad5[2]; /* 0x1ed */ /* * The sentinel is set to a nonzero value (0xff) in header.S. * diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f8ec578..deeb7bc 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1129,6 +1129,12 @@ void __init setup_arch(char **cmdline_p) io_delay_init(); +#ifdef CONFIG_EFI_SECURE_BOOT_SIG_ENFORCE + if (boot_params.secure_boot) { + enforce_signed_modules(); + } +#endif + /* * Parse the ACPI tables for possible boot-time SMP configuration. */ diff --git a/include/linux/module.h b/include/linux/module.h index 0c266b2..5a6374a 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -184,6 +184,12 @@ const struct exception_table_entry *search_exception_tables(unsigned long add); struct notifier_block; +#ifdef CONFIG_MODULE_SIG +extern void enforce_signed_modules(void); +#else +static inline void enforce_signed_modules(void) {}; +#endif + #ifdef CONFIG_MODULES extern int modules_disabled; /* for sysctl */ diff --git a/kernel/module.c b/kernel/module.c index 0e94acf..974139b 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3853,6 +3853,13 @@ void module_layout(struct module *mod, EXPORT_SYMBOL(module_layout); #endif +#ifdef CONFIG_MODULE_SIG +void enforce_signed_modules(void) +{ + sig_enforce = true; +} +#endif + bool secure_modules(void) { #ifdef CONFIG_MODULE_SIG -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/