From 6b6203b92cfb457a0669a9c87a29b360405bffc6 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Fri, 9 Aug 2013 18:36:30 -0400 Subject: [PATCH 10/20] Add option to automatically enforce module signatures when in Secure Boot mode 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 | 11 ++++++ arch/x86/boot/compressed/eboot.c | 66 +++++++++++++++++++++++++++++++++++ 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, 100 insertions(+), 1 deletion(-) diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt index 95a4d34af3fd..b8527c6b7646 100644 --- a/Documentation/x86/zero-page.txt +++ b/Documentation/x86/zero-page.txt @@ -31,6 +31,8 @@ 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 bada636d1065..d666ef8b616c 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1786,6 +1786,17 @@ config EFI_MIXED If unsure, say N. +config EFI_SECURE_BOOT_SIG_ENFORCE + def_bool n + depends on EFI + 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 cc69e37548db..ebc85c1eefd6 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -12,6 +12,7 @@ #include #include #include +#include #include "../string.h" #include "eboot.h" @@ -537,6 +538,67 @@ static void setup_efi_pci(struct boot_params *params) efi_call_early(free_pool, pci_handle); } +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_early->call((unsigned long)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_early->call((unsigned long)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; +} + + +/* + * See if we have Graphics Output Protocol + */ +static efi_status_t setup_gop(struct screen_info *si, efi_guid_t *proto, + unsigned long size) +{ + efi_status_t status; + void **gop_handle = NULL; + + status = efi_call_early(allocate_pool, EFI_LOADER_DATA, + size, (void **)&gop_handle); + if (status != EFI_SUCCESS) + return status; + + status = efi_call_early(locate_handle, + EFI_LOCATE_BY_PROTOCOL, + proto, NULL, &size, gop_handle); + if (status != EFI_SUCCESS) + goto free_handle; + + if (efi_early->is64) + status = setup_gop64(si, proto, size, gop_handle); + else + status = setup_gop32(si, proto, size, gop_handle); + +free_handle: + efi_call_early(free_pool, gop_handle); + return status; +} + static efi_status_t setup_uga32(void **uga_handle, unsigned long size, u32 *width, u32 *height) { @@ -1094,6 +1156,10 @@ struct boot_params *efi_main(struct efi_config *c, else setup_boot_services32(efi_early); + 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 c18ce67495fa..2b3e5427097b 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -134,7 +134,8 @@ 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 bbfbca5fea0c..d40e961753c9 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1160,6 +1160,12 @@ 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 05bd6c989a0c..32327704e18d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -260,6 +260,12 @@ extern const typeof(name) __mod_##type##__##name##_device_table \ 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 cb864505d020..cb1f1da69bf4 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -4285,6 +4285,13 @@ 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 -- 2.9.3