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kernel/secure-boot-20130124.patch
Josh Boyer a8e5aec61f Update secure-boot patchset
2013-01-24 16:56:31 -05:00

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From 10271230f790bda30cd4f6767fce25ad6da4a9cf Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Wed, 14 Nov 2012 09:42:35 +0000
Subject: [PATCH 1/2] efi: Make 'efi_enabled' a function to query EFI
facilities
Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.
The immediate motivation for this patch is the bug report at,
https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,
https://bugzilla.kernel.org/show_bug.cgi?id=47121
details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,
if (!efi_enabled)
hasn't been a sufficient condition for quite some time.
Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.
For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).
Cc: David Airlie <airlied@linux.ie>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Peter Jones <pjones@redhat.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@vger.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
arch/x86/include/asm/efi.h | 1 +
arch/x86/kernel/reboot.c | 2 +-
arch/x86/kernel/setup.c | 28 ++++++++---------
arch/x86/platform/efi/efi.c | 57 ++++++++++++++++++++--------------
drivers/acpi/osl.c | 2 +-
drivers/firmware/dmi_scan.c | 2 +-
drivers/firmware/efivars.c | 4 +--
drivers/firmware/iscsi_ibft_find.c | 2 +-
drivers/gpu/drm/radeon/radeon_device.c | 3 +-
drivers/platform/x86/ibm_rtl.c | 2 +-
drivers/scsi/isci/init.c | 2 +-
include/linux/efi.h | 24 ++++++++++----
init/main.c | 4 +--
13 files changed, 79 insertions(+), 54 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 6e8fdf5..28677c5 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -94,6 +94,7 @@ extern void __iomem *efi_ioremap(unsigned long addr, unsigned long size,
#endif /* CONFIG_X86_32 */
extern int add_efi_memmap;
+extern unsigned long x86_efi_facility;
extern void efi_set_executable(efi_memory_desc_t *md, bool executable);
extern int efi_memblock_x86_reserve_range(void);
extern void efi_call_phys_prelog(void);
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 4e8ba39..76fa1e9 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -584,7 +584,7 @@ static void native_machine_emergency_restart(void)
break;
case BOOT_EFI:
- if (efi_enabled)
+ if (efi_enabled(EFI_RUNTIME_SERVICES))
efi.reset_system(reboot_mode ?
EFI_RESET_WARM :
EFI_RESET_COLD,
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 23ddd55..dbc7369 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -729,15 +729,15 @@ void __init setup_arch(char **cmdline_p)
#ifdef CONFIG_EFI
if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,
"EL32", 4)) {
- efi_enabled = 1;
- efi_64bit = false;
+ set_bit(EFI_BOOT, &x86_efi_facility);
} else if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,
"EL64", 4)) {
- efi_enabled = 1;
- efi_64bit = true;
+ set_bit(EFI_BOOT, &x86_efi_facility);
+ set_bit(EFI_64BIT, &x86_efi_facility);
}
- if (efi_enabled && efi_memblock_x86_reserve_range())
- efi_enabled = 0;
+
+ if (efi_enabled(EFI_BOOT))
+ efi_memblock_x86_reserve_range();
#endif
x86_init.oem.arch_setup();
@@ -810,7 +810,7 @@ void __init setup_arch(char **cmdline_p)
finish_e820_parsing();
- if (efi_enabled)
+ if (efi_enabled(EFI_BOOT))
efi_init();
dmi_scan_machine();
@@ -893,7 +893,7 @@ void __init setup_arch(char **cmdline_p)
* The EFI specification says that boot service code won't be called
* after ExitBootServices(). This is, in fact, a lie.
*/
- if (efi_enabled)
+ if (efi_enabled(EFI_MEMMAP))
efi_reserve_boot_services();
/* preallocate 4k for mptable mpc */
@@ -1034,7 +1034,7 @@ void __init setup_arch(char **cmdline_p)
#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
- if (!efi_enabled || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY))
+ if (!efi_enabled(EFI_BOOT) || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY))
conswitchp = &vga_con;
#elif defined(CONFIG_DUMMY_CONSOLE)
conswitchp = &dummy_con;
@@ -1051,14 +1051,14 @@ void __init setup_arch(char **cmdline_p)
register_refined_jiffies(CLOCK_TICK_RATE);
#ifdef CONFIG_EFI
- /* Once setup is done above, disable efi_enabled on mismatched
- * firmware/kernel archtectures since there is no support for
- * runtime services.
+ /* Once setup is done above, unmap the EFI memory map on
+ * mismatched firmware/kernel archtectures since there is no
+ * support for runtime services.
*/
- if (efi_enabled && IS_ENABLED(CONFIG_X86_64) != efi_64bit) {
+ if (efi_enabled(EFI_BOOT) &&
+ IS_ENABLED(CONFIG_X86_64) != efi_enabled(EFI_64BIT)) {
pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");
efi_unmap_memmap();
- efi_enabled = 0;
}
#endif
}
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index ad44391..5426e48 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -51,9 +51,6 @@
#define EFI_DEBUG 1
-int efi_enabled;
-EXPORT_SYMBOL(efi_enabled);
-
struct efi __read_mostly efi = {
.mps = EFI_INVALID_TABLE_ADDR,
.acpi = EFI_INVALID_TABLE_ADDR,
@@ -69,19 +66,28 @@ EXPORT_SYMBOL(efi);
struct efi_memory_map memmap;
-bool efi_64bit;
-
static struct efi efi_phys __initdata;
static efi_system_table_t efi_systab __initdata;
static inline bool efi_is_native(void)
{
- return IS_ENABLED(CONFIG_X86_64) == efi_64bit;
+ return IS_ENABLED(CONFIG_X86_64) == efi_enabled(EFI_64BIT);
+}
+
+unsigned long x86_efi_facility;
+
+/*
+ * Returns 1 if 'facility' is enabled, 0 otherwise.
+ */
+int efi_enabled(int facility)
+{
+ return test_bit(facility, &x86_efi_facility) != 0;
}
+EXPORT_SYMBOL(efi_enabled);
static int __init setup_noefi(char *arg)
{
- efi_enabled = 0;
+ clear_bit(EFI_BOOT, &x86_efi_facility);
return 0;
}
early_param("noefi", setup_noefi);
@@ -426,6 +432,7 @@ void __init efi_reserve_boot_services(void)
void __init efi_unmap_memmap(void)
{
+ clear_bit(EFI_MEMMAP, &x86_efi_facility);
if (memmap.map) {
early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size);
memmap.map = NULL;
@@ -460,7 +467,7 @@ void __init efi_free_boot_services(void)
static int __init efi_systab_init(void *phys)
{
- if (efi_64bit) {
+ if (efi_enabled(EFI_64BIT)) {
efi_system_table_64_t *systab64;
u64 tmp = 0;
@@ -552,7 +559,7 @@ static int __init efi_config_init(u64 tables, int nr_tables)
void *config_tables, *tablep;
int i, sz;
- if (efi_64bit)
+ if (efi_enabled(EFI_64BIT))
sz = sizeof(efi_config_table_64_t);
else
sz = sizeof(efi_config_table_32_t);
@@ -572,7 +579,7 @@ static int __init efi_config_init(u64 tables, int nr_tables)
efi_guid_t guid;
unsigned long table;
- if (efi_64bit) {
+ if (efi_enabled(EFI_64BIT)) {
u64 table64;
guid = ((efi_config_table_64_t *)tablep)->guid;
table64 = ((efi_config_table_64_t *)tablep)->table;
@@ -684,7 +691,6 @@ void __init efi_init(void)
if (boot_params.efi_info.efi_systab_hi ||
boot_params.efi_info.efi_memmap_hi) {
pr_info("Table located above 4GB, disabling EFI.\n");
- efi_enabled = 0;
return;
}
efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
@@ -694,10 +700,10 @@ void __init efi_init(void)
((__u64)boot_params.efi_info.efi_systab_hi<<32));
#endif
- if (efi_systab_init(efi_phys.systab)) {
- efi_enabled = 0;
+ if (efi_systab_init(efi_phys.systab))
return;
- }
+
+ set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility);
/*
* Show what we know for posterity
@@ -715,10 +721,10 @@ void __init efi_init(void)
efi.systab->hdr.revision >> 16,
efi.systab->hdr.revision & 0xffff, vendor);
- if (efi_config_init(efi.systab->tables, efi.systab->nr_tables)) {
- efi_enabled = 0;
+ if (efi_config_init(efi.systab->tables, efi.systab->nr_tables))
return;
- }
+
+ set_bit(EFI_CONFIG_TABLES, &x86_efi_facility);
/*
* Note: We currently don't support runtime services on an EFI
@@ -727,15 +733,17 @@ void __init efi_init(void)
if (!efi_is_native())
pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
- else if (efi_runtime_init()) {
- efi_enabled = 0;
- return;
+ else {
+ if (efi_runtime_init())
+ return;
+ set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
}
- if (efi_memmap_init()) {
- efi_enabled = 0;
+ if (efi_memmap_init())
return;
- }
+
+ set_bit(EFI_MEMMAP, &x86_efi_facility);
+
#ifdef CONFIG_X86_32
if (efi_is_native()) {
x86_platform.get_wallclock = efi_get_time;
@@ -969,6 +977,9 @@ u32 efi_mem_type(unsigned long phys_addr)
efi_memory_desc_t *md;
void *p;
+ if (!efi_enabled(EFI_MEMMAP))
+ return 0;
+
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
md = p;
if ((md->phys_addr <= phys_addr) &&
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 3ff2678..bd22f86 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -250,7 +250,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
return acpi_rsdp;
#endif
- if (efi_enabled) {
+ if (efi_enabled(EFI_CONFIG_TABLES)) {
if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
return efi.acpi20;
else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index fd3ae62..982f1f5 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -471,7 +471,7 @@ void __init dmi_scan_machine(void)
char __iomem *p, *q;
int rc;
- if (efi_enabled) {
+ if (efi_enabled(EFI_CONFIG_TABLES)) {
if (efi.smbios == EFI_INVALID_TABLE_ADDR)
goto error;
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 7b1c374..1065119 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1782,7 +1782,7 @@ efivars_init(void)
printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
EFIVARS_DATE);
- if (!efi_enabled)
+ if (!efi_enabled(EFI_RUNTIME_SERVICES))
return 0;
/* For now we'll register the efi directory at /sys/firmware/efi */
@@ -1822,7 +1822,7 @@ err_put:
static void __exit
efivars_exit(void)
{
- if (efi_enabled) {
+ if (efi_enabled(EFI_RUNTIME_SERVICES)) {
unregister_efivars(&__efivars);
kobject_put(efi_kobj);
}
diff --git a/drivers/firmware/iscsi_ibft_find.c b/drivers/firmware/iscsi_ibft_find.c
index 4da4eb9..2224f1d 100644
--- a/drivers/firmware/iscsi_ibft_find.c
+++ b/drivers/firmware/iscsi_ibft_find.c
@@ -99,7 +99,7 @@ unsigned long __init find_ibft_region(unsigned long *sizep)
/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
* only use ACPI for this */
- if (!efi_enabled)
+ if (!efi_enabled(EFI_BOOT))
find_ibft_in_mem();
if (ibft_addr) {
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index cd75626..9a68174 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -429,7 +429,8 @@ bool radeon_card_posted(struct radeon_device *rdev)
{
uint32_t reg;
- if (efi_enabled && rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE)
+ if (efi_enabled(EFI_BOOT) &&
+ rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE)
return false;
/* first check CRTCs */
diff --git a/drivers/platform/x86/ibm_rtl.c b/drivers/platform/x86/ibm_rtl.c
index 7481146..97c2be1 100644
--- a/drivers/platform/x86/ibm_rtl.c
+++ b/drivers/platform/x86/ibm_rtl.c
@@ -244,7 +244,7 @@ static int __init ibm_rtl_init(void) {
if (force)
pr_warn("module loaded by force\n");
/* first ensure that we are running on IBM HW */
- else if (efi_enabled || !dmi_check_system(ibm_rtl_dmi_table))
+ else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
return -ENODEV;
/* Get the address for the Extended BIOS Data Area */
diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index b74050b..9ac1e9d 100644
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -633,7 +633,7 @@ static int __devinit isci_pci_probe(struct pci_dev *pdev, const struct pci_devic
return -ENOMEM;
pci_set_drvdata(pdev, pci_info);
- if (efi_enabled)
+ if (efi_enabled(EFI_RUNTIME_SERVICES))
orom = isci_get_efi_var(pdev);
if (!orom)
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8b84916..7a9498a 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -618,18 +618,30 @@ extern int __init efi_setup_pcdp_console(char *);
#endif
/*
- * We play games with efi_enabled so that the compiler will, if possible, remove
- * EFI-related code altogether.
+ * We play games with efi_enabled so that the compiler will, if
+ * possible, remove EFI-related code altogether.
*/
+#define EFI_BOOT 0 /* Were we booted from EFI? */
+#define EFI_SYSTEM_TABLES 1 /* Can we use EFI system tables? */
+#define EFI_CONFIG_TABLES 2 /* Can we use EFI config tables? */
+#define EFI_RUNTIME_SERVICES 3 /* Can we use runtime services? */
+#define EFI_MEMMAP 4 /* Can we use EFI memory map? */
+#define EFI_64BIT 5 /* Is the firmware 64-bit? */
+
#ifdef CONFIG_EFI
# ifdef CONFIG_X86
- extern int efi_enabled;
- extern bool efi_64bit;
+extern int efi_enabled(int facility);
# else
-# define efi_enabled 1
+static inline int efi_enabled(int facility)
+{
+ return 1;
+}
# endif
#else
-# define efi_enabled 0
+static inline int efi_enabled(int facility)
+{
+ return 0;
+}
#endif
/*
diff --git a/init/main.c b/init/main.c
index 85d69df..cd30179 100644
--- a/init/main.c
+++ b/init/main.c
@@ -604,7 +604,7 @@ asmlinkage void __init start_kernel(void)
pidmap_init();
anon_vma_init();
#ifdef CONFIG_X86
- if (efi_enabled)
+ if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
thread_info_cache_init();
@@ -632,7 +632,7 @@ asmlinkage void __init start_kernel(void)
acpi_early_init(); /* before LAPIC and SMP init */
sfi_init_late();
- if (efi_enabled) {
+ if (efi_enabled(EFI_RUNTIME_SERVICES)) {
efi_late_init();
efi_free_boot_services();
}
--
1.8.1
From 87123c25437f0da326b2f63cae8ab9aabac6fd6c Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Thu, 3 Jan 2013 09:02:37 +0000
Subject: [PATCH 2/2] samsung-laptop: Disable on EFI hardware
It has been reported that running this driver on some Samsung laptops
with EFI can cause those machines to become bricked as detailed in the
following report,
https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
There have also been reports of this driver causing Machine Check
Exceptions on recent EFI-enabled Samsung laptops,
https://bugzilla.kernel.org/show_bug.cgi?id=47121
So disable it if booting from EFI since this driver relies on
grovelling around in the BIOS memory map which isn't going to work.
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: platform-driver-x86@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
drivers/platform/x86/samsung-laptop.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
index dd90d15..5a89ca1 100644
--- a/drivers/platform/x86/samsung-laptop.c
+++ b/drivers/platform/x86/samsung-laptop.c
@@ -26,6 +26,7 @@
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/ctype.h>
+#include <linux/efi.h>
#include <acpi/video.h>
/*
@@ -1534,6 +1535,9 @@ static int __init samsung_init(void)
struct samsung_laptop *samsung;
int ret;
+ if (efi_enabled(EFI_BOOT))
+ return -ENODEV;
+
quirks = &samsung_unknown;
if (!force && !dmi_check_system(samsung_dmi_table))
return -ENODEV;
--
1.8.1
From 078aac950b94287072864fe8db0c690b8343f364 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:56 -0400
Subject: [PATCH 03/19] Secure boot: Add new capability
Secure boot adds certain policy requirements, including that root must not
be able to do anything that could cause the kernel to execute arbitrary code.
The simplest way to handle this would seem to be to add a new capability
and gate various functionality on that. We'll then strip it from the initial
capability set if required.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
include/uapi/linux/capability.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index ba478fa..7109e65 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -343,7 +343,11 @@ struct vfs_cap_data {
#define CAP_BLOCK_SUSPEND 36
-#define CAP_LAST_CAP CAP_BLOCK_SUSPEND
+/* Allow things that trivially permit root to modify the running kernel */
+
+#define CAP_COMPROMISE_KERNEL 37
+
+#define CAP_LAST_CAP CAP_COMPROMISE_KERNEL
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
--
1.8.1
From b3f043c11522faad4a0a2ed54bc204af9157f4cf Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:05 -0400
Subject: [PATCH 04/19] SELinux: define mapping for new Secure Boot capability
Add the name of the new Secure Boot capability. This allows SELinux
policies to properly map CAP_COMPROMISE_KERNEL to the appropriate
capability class.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
security/selinux/include/classmap.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index df2de54..70e2834 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -146,8 +146,8 @@ struct security_class_mapping secclass_map[] = {
{ "memprotect", { "mmap_zero", NULL } },
{ "peer", { "recv", NULL } },
{ "capability2",
- { "mac_override", "mac_admin", "syslog", "wake_alarm", "block_suspend",
- NULL } },
+ { "mac_override", "mac_admin", "syslog", "wake_alarm",
+ "block_suspend", "compromise_kernel", NULL } },
{ "kernel_service", { "use_as_override", "create_files_as", NULL } },
{ "tun_socket",
{ COMMON_SOCK_PERMS, NULL } },
--
1.8.1
From 91a1c56865bb3c8caf452df78af91bb8c2bdee57 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:02 -0400
Subject: [PATCH 05/19] Secure boot: Add a dummy kernel parameter that will
switch on Secure Boot mode
This forcibly drops CAP_COMPROMISE_KERNEL from both cap_permitted and cap_bset
in the init_cred struct, which everything else inherits from. This works on
any machine and can be used to develop even if the box doesn't have UEFI.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
Documentation/kernel-parameters.txt | 7 +++++++
kernel/cred.c | 17 +++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 363e348..832b39b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2654,6 +2654,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Note: increases power consumption, thus should only be
enabled if running jitter sensitive (HPC/RT) workloads.
+ secureboot_enable=
+ [KNL] Enables an emulated UEFI Secure Boot mode. This
+ locks down various aspects of the kernel guarded by the
+ CAP_COMPROMISE_KERNEL capability. This includes things
+ like /dev/mem, IO port access, and other areas. It can
+ be used on non-UEFI machines for testing purposes.
+
security= [SECURITY] Choose a security module to enable at boot.
If this boot parameter is not specified, only the first
security module asking for security registration will be
diff --git a/kernel/cred.c b/kernel/cred.c
index e0573a4..c3f4e3e 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -565,6 +565,23 @@ void __init cred_init(void)
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
}
+void __init secureboot_enable()
+{
+ pr_info("Secure boot enabled\n");
+ cap_lower((&init_cred)->cap_bset, CAP_COMPROMISE_KERNEL);
+ cap_lower((&init_cred)->cap_permitted, CAP_COMPROMISE_KERNEL);
+}
+
+/* Dummy Secure Boot enable option to fake out UEFI SB=1 */
+static int __init secureboot_enable_opt(char *str)
+{
+ int sb_enable = !!simple_strtol(str, NULL, 0);
+ if (sb_enable)
+ secureboot_enable();
+ return 1;
+}
+__setup("secureboot_enable=", secureboot_enable_opt);
+
/**
* prepare_kernel_cred - Prepare a set of credentials for a kernel service
* @daemon: A userspace daemon to be used as a reference
--
1.8.1
From 39585d1c3c7fa8878889d88e00a3aa5a647c024f Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:03 -0400
Subject: [PATCH 06/19] efi: Enable secure boot lockdown automatically when
enabled in firmware
The firmware has a set of flags that indicate whether secure boot is enabled
and enforcing. Use them to indicate whether the kernel should lock itself
down. We also indicate the machine is in secure boot mode by adding the
EFI_SECURE_BOOT bit for use with efi_enabled.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
Documentation/x86/zero-page.txt | 2 ++
arch/x86/boot/compressed/eboot.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/include/uapi/asm/bootparam.h | 3 ++-
arch/x86/kernel/setup.c | 5 +++++
include/linux/cred.h | 2 ++
include/linux/efi.h | 1 +
6 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
index cf5437d..7f9ed48 100644
--- a/Documentation/x86/zero-page.txt
+++ b/Documentation/x86/zero-page.txt
@@ -27,6 +27,8 @@ 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 Kernel should enable secure boot lockdowns
290/040 ALL edd_mbr_sig_buffer EDD MBR signatures
2D0/A00 ALL e820_map E820 memory map table
(array of struct e820entry)
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 18e329c..f44adce 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -848,6 +848,36 @@ fail:
return status;
}
+static int get_secure_boot(efi_system_table_t *_table)
+{
+ 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
@@ -1142,6 +1172,8 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
goto fail;
+ boot_params->secure_boot = get_secure_boot(sys_table);
+
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 92862cd..422e056 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -115,7 +115,8 @@ struct boot_params {
__u8 eddbuf_entries; /* 0x1e9 */
__u8 edd_mbr_sig_buf_entries; /* 0x1ea */
__u8 kbd_status; /* 0x1eb */
- __u8 _pad6[5]; /* 0x1ec */
+ __u8 secure_boot; /* 0x1ec */
+ __u8 _pad6[4]; /* 0x1ed */
struct setup_header hdr; /* setup header */ /* 0x1f1 */
__u8 _pad7[0x290-0x1f1-sizeof(struct setup_header)];
__u32 edd_mbr_sig_buffer[EDD_MBR_SIG_MAX]; /* 0x290 */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 8b24289..5355a54 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1042,6 +1042,11 @@ void __init setup_arch(char **cmdline_p)
io_delay_init();
+ if (boot_params.secure_boot) {
+ set_bit(EFI_SECURE_BOOT, &x86_efi_facility);
+ secureboot_enable();
+ }
+
/*
* Parse the ACPI tables for possible boot-time SMP configuration.
*/
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 04421e8..9e69542 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -156,6 +156,8 @@ extern int set_security_override_from_ctx(struct cred *, const char *);
extern int set_create_files_as(struct cred *, struct inode *);
extern void __init cred_init(void);
+extern void secureboot_enable(void);
+
/*
* check for validity of credentials
*/
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 7a9498a..1ae16b6 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -627,6 +627,7 @@ extern int __init efi_setup_pcdp_console(char *);
#define EFI_RUNTIME_SERVICES 3 /* Can we use runtime services? */
#define EFI_MEMMAP 4 /* Can we use EFI memory map? */
#define EFI_64BIT 5 /* Is the firmware 64-bit? */
+#define EFI_SECURE_BOOT 6 /* Are we in Secure Boot mode? */
#ifdef CONFIG_EFI
# ifdef CONFIG_X86
--
1.8.1
From c4913bd0af536c2e752da503e34cfdbdef2ca427 Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:30:54 -0400
Subject: [PATCH 07/19] Add EFI signature data types
Add the data types that are used for containing hashes, keys and certificates
for cryptographic verification.
Signed-off-by: David Howells <dhowells@redhat.com>
---
include/linux/efi.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 1ae16b6..de7021d 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -388,6 +388,12 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
#define EFI_FILE_SYSTEM_GUID \
EFI_GUID( 0x964e5b22, 0x6459, 0x11d2, 0x8e, 0x39, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b )
+#define EFI_CERT_SHA256_GUID \
+ EFI_GUID( 0xc1c41626, 0x504c, 0x4092, 0xac, 0xa9, 0x41, 0xf9, 0x36, 0x93, 0x43, 0x28 )
+
+#define EFI_CERT_X509_GUID \
+ EFI_GUID( 0xa5c059a1, 0x94e4, 0x4aa7, 0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72 )
+
typedef struct {
efi_guid_t guid;
u64 table;
@@ -523,6 +529,20 @@ typedef struct {
#define EFI_INVALID_TABLE_ADDR (~0UL)
+typedef struct {
+ efi_guid_t signature_owner;
+ u8 signature_data[];
+} efi_signature_data_t;
+
+typedef struct {
+ efi_guid_t signature_type;
+ u32 signature_list_size;
+ u32 signature_header_size;
+ u32 signature_size;
+ u8 signature_header[];
+ /* efi_signature_data_t signatures[][] */
+} efi_signature_list_t;
+
/*
* All runtime access to EFI goes through this structure:
*/
--
1.8.1
From 714ab7855166f5cf453817de90b80ea8f132715d Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:36:28 -0400
Subject: [PATCH 08/19] Add an EFI signature blob parser and key loader.
X.509 certificates are loaded into the specified keyring as asymmetric type
keys.
Signed-off-by: David Howells <dhowells@redhat.com>
---
crypto/asymmetric_keys/Kconfig | 8 +++
crypto/asymmetric_keys/Makefile | 1 +
crypto/asymmetric_keys/efi_parser.c | 108 ++++++++++++++++++++++++++++++++++++
include/linux/efi.h | 4 ++
4 files changed, 121 insertions(+)
create mode 100644 crypto/asymmetric_keys/efi_parser.c
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 6d2c2ea..ace9c30 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -35,4 +35,12 @@ config X509_CERTIFICATE_PARSER
data and provides the ability to instantiate a crypto key from a
public key packet found inside the certificate.
+config EFI_SIGNATURE_LIST_PARSER
+ bool "EFI signature list parser"
+ depends on EFI
+ select X509_CERTIFICATE_PARSER
+ help
+ This option provides support for parsing EFI signature lists for
+ X.509 certificates and turning them into keys.
+
endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 0727204..cd8388e 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -8,6 +8,7 @@ asymmetric_keys-y := asymmetric_type.o signature.o
obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
+obj-$(CONFIG_EFI_SIGNATURE_LIST_PARSER) += efi_parser.o
#
# X.509 Certificate handling
diff --git a/crypto/asymmetric_keys/efi_parser.c b/crypto/asymmetric_keys/efi_parser.c
new file mode 100644
index 0000000..636feb1
--- /dev/null
+++ b/crypto/asymmetric_keys/efi_parser.c
@@ -0,0 +1,108 @@
+/* EFI signature/key/certificate list parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "EFI: "fmt
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/err.h>
+#include <linux/efi.h>
+#include <keys/asymmetric-type.h>
+
+static __initdata efi_guid_t efi_cert_x509_guid = EFI_CERT_X509_GUID;
+
+/**
+ * parse_efi_signature_list - Parse an EFI signature list for certificates
+ * @data: The data blob to parse
+ * @size: The size of the data blob
+ * @keyring: The keyring to add extracted keys to
+ */
+int __init parse_efi_signature_list(const void *data, size_t size, struct key *keyring)
+{
+ unsigned offs = 0;
+ size_t lsize, esize, hsize, elsize;
+
+ pr_devel("-->%s(,%zu)\n", __func__, size);
+
+ while (size > 0) {
+ efi_signature_list_t list;
+ const efi_signature_data_t *elem;
+ key_ref_t key;
+
+ if (size < sizeof(list))
+ return -EBADMSG;
+
+ memcpy(&list, data, sizeof(list));
+ pr_devel("LIST[%04x] guid=%pUl ls=%x hs=%x ss=%x\n",
+ offs,
+ list.signature_type.b, list.signature_list_size,
+ list.signature_header_size, list.signature_size);
+
+ lsize = list.signature_list_size;
+ hsize = list.signature_header_size;
+ esize = list.signature_size;
+ elsize = lsize - sizeof(list) - hsize;
+
+ if (lsize > size) {
+ pr_devel("<--%s() = -EBADMSG [overrun @%x]\n",
+ __func__, offs);
+ return -EBADMSG;
+ }
+ if (lsize < sizeof(list) ||
+ lsize - sizeof(list) < hsize ||
+ esize < sizeof(*elem) ||
+ elsize < esize ||
+ elsize % esize != 0) {
+ pr_devel("- bad size combo @%x\n", offs);
+ return -EBADMSG;
+ }
+
+ if (efi_guidcmp(list.signature_type, efi_cert_x509_guid) != 0) {
+ data += lsize;
+ size -= lsize;
+ offs += lsize;
+ continue;
+ }
+
+ data += sizeof(list) + hsize;
+ size -= sizeof(list) + hsize;
+ offs += sizeof(list) + hsize;
+
+ for (; elsize > 0; elsize -= esize) {
+ elem = data;
+
+ pr_devel("ELEM[%04x]\n", offs);
+
+ key = key_create_or_update(
+ make_key_ref(keyring, 1),
+ "asymmetric",
+ NULL,
+ &elem->signature_data,
+ esize - sizeof(*elem),
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW,
+ KEY_ALLOC_NOT_IN_QUOTA);
+
+ if (IS_ERR(key))
+ pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
+ PTR_ERR(key));
+ else
+ pr_notice("Loaded cert '%s' linked to '%s'\n",
+ key_ref_to_ptr(key)->description,
+ keyring->description);
+
+ data += esize;
+ size -= esize;
+ offs += esize;
+ }
+ }
+
+ return 0;
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index de7021d..64b3e55 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -612,6 +612,10 @@ extern int efi_set_rtc_mmss(unsigned long nowtime);
extern void efi_reserve_boot_services(void);
extern struct efi_memory_map memmap;
+struct key;
+extern int __init parse_efi_signature_list(const void *data, size_t size,
+ struct key *keyring);
+
/**
* efi_range_is_wc - check the WC bit on an address range
* @start: starting kvirt address
--
1.8.1
From e485260e14c366644a44d2fea05fc3e7dc02a8c3 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 12:36:24 -0400
Subject: [PATCH 09/19] MODSIGN: Add module certificate blacklist keyring
This adds an additional keyring that is used to store certificates that
are blacklisted. This keyring is searched first when loading signed modules
and if the module's certificate is found, it will refuse to load. This is
useful in cases where third party certificates are used for module signing.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
init/Kconfig | 8 ++++++++
kernel/modsign_pubkey.c | 14 ++++++++++++++
kernel/module-internal.h | 3 +++
kernel/module_signing.c | 12 ++++++++++++
4 files changed, 37 insertions(+)
diff --git a/init/Kconfig b/init/Kconfig
index be8b7f5..d972b77 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1665,6 +1665,14 @@ config MODULE_SIG_FORCE
Reject unsigned modules or signed modules for which we don't have a
key. Without this, such modules will simply taint the kernel.
+config MODULE_SIG_BLACKLIST
+ bool "Support for blacklisting module signature certificates"
+ depends on MODULE_SIG
+ help
+ This adds support for keeping a blacklist of certificates that
+ should not pass module signature verification. If a module is
+ signed with something in this keyring, the load will be rejected.
+
choice
prompt "Which hash algorithm should modules be signed with?"
depends on MODULE_SIG
diff --git a/kernel/modsign_pubkey.c b/kernel/modsign_pubkey.c
index 2b6e699..4cd408d 100644
--- a/kernel/modsign_pubkey.c
+++ b/kernel/modsign_pubkey.c
@@ -17,6 +17,9 @@
#include "module-internal.h"
struct key *modsign_keyring;
+#ifdef CONFIG_MODULE_SIG_BLACKLIST
+struct key *modsign_blacklist;
+#endif
extern __initdata const u8 modsign_certificate_list[];
extern __initdata const u8 modsign_certificate_list_end[];
@@ -43,6 +46,17 @@ static __init int module_verify_init(void)
if (IS_ERR(modsign_keyring))
panic("Can't allocate module signing keyring\n");
+#ifdef CONFIG_MODULE_SIG_BLACKLIST
+ modsign_blacklist = keyring_alloc(".modsign_blacklist",
+ KUIDT_INIT(0), KGIDT_INIT(0),
+ current_cred(),
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ,
+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
+ if (IS_ERR(modsign_blacklist))
+ panic("Can't allocate module signing blacklist keyring\n");
+#endif
+
return 0;
}
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 24f9247..51a8380 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -10,5 +10,8 @@
*/
extern struct key *modsign_keyring;
+#ifdef CONFIG_MODULE_SIG_BLACKLIST
+extern struct key *modsign_blacklist;
+#endif
extern int mod_verify_sig(const void *mod, unsigned long *_modlen);
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index f2970bd..5423195 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -157,6 +157,18 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len,
pr_debug("Look up: \"%s\"\n", id);
+#ifdef CONFIG_MODULE_SIG_BLACKLIST
+ key = keyring_search(make_key_ref(modsign_blacklist, 1),
+ &key_type_asymmetric, id);
+ if (!IS_ERR(key)) {
+ /* module is signed with a cert in the blacklist. reject */
+ pr_err("Module key '%s' is in blacklist\n", id);
+ key_ref_put(key);
+ kfree(id);
+ return ERR_PTR(-EKEYREJECTED);
+ }
+#endif
+
key = keyring_search(make_key_ref(modsign_keyring, 1),
&key_type_asymmetric, id);
if (IS_ERR(key))
--
1.8.1
From 2015a3299fb6029de0c1e4da3e06bfa74e1075df Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 12:42:16 -0400
Subject: [PATCH 10/19] MODSIGN: Import certificates from UEFI Secure Boot
Secure Boot stores a list of allowed certificates in the 'db' variable.
This imports those certificates into the module signing keyring. This
allows for a third party signing certificate to be used in conjunction
with signed modules. By importing the public certificate into the 'db'
variable, a user can allow a module signed with that certificate to
load. The shim UEFI bootloader has a similar certificate list stored
in the 'MokListRT' variable. We import those as well.
In the opposite case, Secure Boot maintains a list of disallowed
certificates in the 'dbx' variable. We load those certificates into
the newly introduced module blacklist keyring and forbid any module
signed with those from loading.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
include/linux/efi.h | 6 ++++
init/Kconfig | 9 ++++++
kernel/Makefile | 3 ++
kernel/modsign_uefi.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 108 insertions(+)
create mode 100644 kernel/modsign_uefi.c
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 64b3e55..76fe526 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -394,6 +394,12 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
#define EFI_CERT_X509_GUID \
EFI_GUID( 0xa5c059a1, 0x94e4, 0x4aa7, 0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72 )
+#define EFI_IMAGE_SECURITY_DATABASE_GUID \
+ EFI_GUID( 0xd719b2cb, 0x3d3a, 0x4596, 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f )
+
+#define EFI_SHIM_LOCK_GUID \
+ EFI_GUID( 0x605dab50, 0xe046, 0x4300, 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23 )
+
typedef struct {
efi_guid_t guid;
u64 table;
diff --git a/init/Kconfig b/init/Kconfig
index d972b77..27e3a82 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1673,6 +1673,15 @@ config MODULE_SIG_BLACKLIST
should not pass module signature verification. If a module is
signed with something in this keyring, the load will be rejected.
+config MODULE_SIG_UEFI
+ bool "Allow modules signed with certs stored in UEFI"
+ depends on MODULE_SIG && MODULE_SIG_BLACKLIST && EFI
+ select EFI_SIGNATURE_LIST_PARSER
+ help
+ This will import certificates stored in UEFI and allow modules
+ signed with those to be loaded. It will also disallow loading
+ of modules stored in the UEFI dbx variable.
+
choice
prompt "Which hash algorithm should modules be signed with?"
depends on MODULE_SIG
diff --git a/kernel/Makefile b/kernel/Makefile
index 6c072b6..8848829 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_MODULE_SIG) += module_signing.o modsign_pubkey.o modsign_certificate.o
+obj-$(CONFIG_MODULE_SIG_UEFI) += modsign_uefi.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
@@ -114,6 +115,8 @@ obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
$(obj)/configs.o: $(obj)/config_data.h
+$(obj)/modsign_uefi.o: KBUILD_CFLAGS += -fshort-wchar
+
# config_data.h contains the same information as ikconfig.h but gzipped.
# Info from config_data can be extracted from /proc/config*
targets += config_data.gz
diff --git a/kernel/modsign_uefi.c b/kernel/modsign_uefi.c
new file mode 100644
index 0000000..b9237d7
--- /dev/null
+++ b/kernel/modsign_uefi.c
@@ -0,0 +1,90 @@
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/efi.h>
+#include <keys/asymmetric-type.h>
+#include "module-internal.h"
+
+static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, unsigned long *size)
+{
+ efi_status_t status;
+ unsigned long lsize = 4;
+ unsigned long tmpdb[4];
+ void *db = NULL;
+
+ status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb);
+ if (status != EFI_BUFFER_TOO_SMALL) {
+ pr_err("Couldn't get size: 0x%lx\n", status);
+ return NULL;
+ }
+
+ db = kmalloc(lsize, GFP_KERNEL);
+ if (!db) {
+ pr_err("Couldn't allocate memory for uefi cert list\n");
+ goto out;
+ }
+
+ status = efi.get_variable(name, guid, NULL, &lsize, db);
+ if (status != EFI_SUCCESS) {
+ kfree(db);
+ db = NULL;
+ pr_err("Error reading db var: 0x%lx\n", status);
+ }
+out:
+ *size = lsize;
+ return db;
+}
+
+/*
+ * * Load the certs contained in the UEFI databases
+ * */
+static int __init load_uefi_certs(void)
+{
+ efi_guid_t secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID;
+ efi_guid_t mok_var = EFI_SHIM_LOCK_GUID;
+ void *db = NULL, *dbx = NULL, *mok = NULL;
+ unsigned long dbsize = 0, dbxsize = 0, moksize = 0;
+ int rc = 0;
+
+ /* Check if SB is enabled and just return if not */
+ if (!efi_enabled(EFI_SECURE_BOOT))
+ return 0;
+
+ /* Get db, MokListRT, and dbx. They might not exist, so it isn't
+ * an error if we can't get them.
+ */
+ db = get_cert_list(L"db", &secure_var, &dbsize);
+ if (!db) {
+ pr_err("MODSIGN: Couldn't get UEFI db list\n");
+ } else {
+ rc = parse_efi_signature_list(db, dbsize, modsign_keyring);
+ if (rc)
+ pr_err("Couldn't parse db signatures: %d\n", rc);
+ kfree(db);
+ }
+
+ mok = get_cert_list(L"MokListRT", &mok_var, &moksize);
+ if (!mok) {
+ pr_info("MODSIGN: Couldn't get UEFI MokListRT\n");
+ } else {
+ rc = parse_efi_signature_list(mok, moksize, modsign_keyring);
+ if (rc)
+ pr_err("Couldn't parse MokListRT signatures: %d\n", rc);
+ kfree(mok);
+ }
+
+ dbx = get_cert_list(L"dbx", &secure_var, &dbxsize);
+ if (!dbx) {
+ pr_info("MODSIGN: Couldn't get UEFI dbx list\n");
+ } else {
+ rc = parse_efi_signature_list(dbx, dbxsize,
+ modsign_blacklist);
+ if (rc)
+ pr_err("Couldn't parse dbx signatures: %d\n", rc);
+ kfree(dbx);
+ }
+
+ return rc;
+}
+late_initcall(load_uefi_certs);
--
1.8.1
From b9003fd1d1ec55049db258832fed7736c3d72703 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:57 -0400
Subject: [PATCH 11/19] PCI: Lock down BAR access in secure boot environments
Any hardware that can potentially generate DMA has to be locked down from
userspace in order to avoid it being possible for an attacker to cause
arbitrary kernel behaviour. Default to paranoid - in future we can
potentially relax this for sufficiently IOMMU-isolated devices.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
drivers/pci/pci-sysfs.c | 9 +++++++++
drivers/pci/proc.c | 8 +++++++-
drivers/pci/syscall.c | 2 +-
3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 9c6e9bb..b966089 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -622,6 +622,9 @@ pci_write_config(struct file* filp, struct kobject *kobj,
loff_t init_off = off;
u8 *data = (u8*) buf;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (off > dev->cfg_size)
return 0;
if (off + count > dev->cfg_size) {
@@ -928,6 +931,9 @@ pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
resource_size_t start, end;
int i;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
for (i = 0; i < PCI_ROM_RESOURCE; i++)
if (res == &pdev->resource[i])
break;
@@ -1035,6 +1041,9 @@ pci_write_resource_io(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t off, size_t count)
{
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
return pci_resource_io(filp, kobj, attr, buf, off, count, true);
}
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 9b8505c..35580bc 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -139,6 +139,9 @@ proc_bus_pci_write(struct file *file, const char __user *buf, size_t nbytes, lof
int size = dp->size;
int cnt;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (pos >= size)
return 0;
if (nbytes >= size)
@@ -219,6 +222,9 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd,
#endif /* HAVE_PCI_MMAP */
int ret = 0;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
switch (cmd) {
case PCIIOC_CONTROLLER:
ret = pci_domain_nr(dev->bus);
@@ -259,7 +265,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
struct pci_filp_private *fpriv = file->private_data;
int i, ret;
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) || !capable(CAP_COMPROMISE_KERNEL))
return -EPERM;
/* Make sure the caller is mapping a real resource for this device */
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
index e1c1ec5..97e785f 100644
--- a/drivers/pci/syscall.c
+++ b/drivers/pci/syscall.c
@@ -92,7 +92,7 @@ SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
u32 dword;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN) || !capable(CAP_COMPROMISE_KERNEL))
return -EPERM;
dev = pci_get_bus_and_slot(bus, dfn);
--
1.8.1
From 66b86238391bae88f1da0fd82f2516d58aa544b9 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:58 -0400
Subject: [PATCH 12/19] x86: Lock down IO port access in secure boot
environments
IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO register
space. This would potentially permit root to trigger arbitrary DMA, so lock
it down by default.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
arch/x86/kernel/ioport.c | 4 ++--
drivers/char/mem.c | 3 +++
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 8c96897..a2578c4 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -28,7 +28,7 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
- if (turn_on && !capable(CAP_SYS_RAWIO))
+ if (turn_on && (!capable(CAP_SYS_RAWIO) || !capable(CAP_COMPROMISE_KERNEL)))
return -EPERM;
/*
@@ -102,7 +102,7 @@ long sys_iopl(unsigned int level, struct pt_regs *regs)
return -EINVAL;
/* Trying to gain more privileges? */
if (level > old) {
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) || !capable(CAP_COMPROMISE_KERNEL))
return -EPERM;
}
regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index c6fa3bc..fc28099 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -597,6 +597,9 @@ static ssize_t write_port(struct file *file, const char __user *buf,
unsigned long i = *ppos;
const char __user * tmp = buf;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
while (count-- > 0 && i < 65536) {
--
1.8.1
From 2bae7bb333fb916824efaa8ebfff296be6b474aa Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:59 -0400
Subject: [PATCH 13/19] ACPI: Limit access to custom_method
It must be impossible for even root to get code executed in kernel context
under a secure boot environment. custom_method effectively allows arbitrary
access to system memory, so it needs to have a capability check here.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
drivers/acpi/custom_method.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index 5d42c24..247d58b 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
struct acpi_table_header table;
acpi_status status;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (!(*ppos)) {
/* parse the table header to get the table length */
if (count <= sizeof(struct acpi_table_header))
--
1.8.1
From 1020b65305173afb24a9411a9555468a5184a73d Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:00 -0400
Subject: [PATCH 14/19] asus-wmi: Restrict debugfs interface
We have no way of validating what all of the Asus WMI methods do on a
given machine, and there's a risk that some will allow hardware state to
be manipulated in such a way that arbitrary code can be executed in the
kernel. Add a capability check to prevent that.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
drivers/platform/x86/asus-wmi.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index f80ae4d..059195f 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -1521,6 +1521,9 @@ static int show_dsts(struct seq_file *m, void *data)
int err;
u32 retval = -1;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
err = asus_wmi_get_devstate(asus, asus->debug.dev_id, &retval);
if (err < 0)
@@ -1537,6 +1540,9 @@ static int show_devs(struct seq_file *m, void *data)
int err;
u32 retval = -1;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
err = asus_wmi_set_devstate(asus->debug.dev_id, asus->debug.ctrl_param,
&retval);
@@ -1561,6 +1567,9 @@ static int show_call(struct seq_file *m, void *data)
union acpi_object *obj;
acpi_status status;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
status = wmi_evaluate_method(ASUS_WMI_MGMT_GUID,
1, asus->debug.method_id,
&input, &output);
--
1.8.1
From 5e940dba25d3d2614a3a745ef7c3057e058c876a Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:01 -0400
Subject: [PATCH 15/19] Restrict /dev/mem and /dev/kmem in secure boot setups
Allowing users to write to address space makes it possible for the kernel
to be subverted. Restrict this when we need to protect the kernel.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
drivers/char/mem.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index fc28099..b5df7a8 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -158,6 +158,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
unsigned long copied;
void *ptr;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (!valid_phys_addr_range(p, count))
return -EFAULT;
@@ -530,6 +533,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf,
char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
int err = 0;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (p < (unsigned long) high_memory) {
unsigned long to_write = min_t(unsigned long, count,
(unsigned long)high_memory - p);
--
1.8.1
From b6264c3ed7a36a7a8d9c504d20a9a639850ace3b Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:04 -0400
Subject: [PATCH 16/19] acpi: Ignore acpi_rsdp kernel parameter in a secure
boot environment
This option allows userspace to pass the RSDP address to the kernel. This
could potentially be used to circumvent the secure boot trust model.
We ignore the setting if we don't have the CAP_COMPROMISE_KERNEL capability.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
drivers/acpi/osl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index bd22f86..88251d2 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -246,7 +246,7 @@ early_param("acpi_rsdp", setup_acpi_rsdp);
acpi_physical_address __init acpi_os_get_root_pointer(void)
{
#ifdef CONFIG_KEXEC
- if (acpi_rsdp)
+ if (acpi_rsdp && capable(CAP_COMPROMISE_KERNEL))
return acpi_rsdp;
#endif
--
1.8.1
From 4f1614d3aae4e924ad8b8d56c66a23a469b1c3d0 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Tue, 4 Sep 2012 11:55:13 -0400
Subject: [PATCH 17/19] kexec: Disable in a secure boot environment
kexec could be used as a vector for a malicious user to use a signed kernel
to circumvent the secure boot trust model. In the long run we'll want to
support signed kexec payloads, but for the moment we should just disable
loading entirely in that situation.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
---
kernel/kexec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 5e4bd78..dd464e0 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -943,7 +943,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
int result;
/* We only trust the superuser with rebooting the system. */
- if (!capable(CAP_SYS_BOOT))
+ if (!capable(CAP_SYS_BOOT) || !capable(CAP_COMPROMISE_KERNEL))
return -EPERM;
/*
--
1.8.1
From 9760ba180b98ff6e6a6e40dfe82973fc6bfcb194 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 5 Oct 2012 10:12:48 -0400
Subject: [PATCH 18/19] MODSIGN: Always enforce module signing in a Secure Boot
environment
If a machine is booted into a Secure Boot environment, we need to
protect the trust model. This requires that all modules be signed
with a key that is in the kernel's _modsign keyring. The checks for
this are already done via the 'sig_enforce' module parameter. Make
this visible within the kernel and force it to be true.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
kernel/cred.c | 8 ++++++++
kernel/module.c | 4 ++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cred.c b/kernel/cred.c
index c3f4e3e..c5554e0 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -565,11 +565,19 @@ void __init cred_init(void)
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
}
+#ifdef CONFIG_MODULE_SIG
+extern bool sig_enforce;
+#endif
+
void __init secureboot_enable()
{
pr_info("Secure boot enabled\n");
cap_lower((&init_cred)->cap_bset, CAP_COMPROMISE_KERNEL);
cap_lower((&init_cred)->cap_permitted, CAP_COMPROMISE_KERNEL);
+#ifdef CONFIG_MODULE_SIG
+ /* Enable module signature enforcing */
+ sig_enforce = true;
+#endif
}
/* Dummy Secure Boot enable option to fake out UEFI SB=1 */
diff --git a/kernel/module.c b/kernel/module.c
index eab0827..93a16dc 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -109,9 +109,9 @@ struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
#ifdef CONFIG_MODULE_SIG
#ifdef CONFIG_MODULE_SIG_FORCE
-static bool sig_enforce = true;
+bool sig_enforce = true;
#else
-static bool sig_enforce = false;
+bool sig_enforce = false;
static int param_set_bool_enable_only(const char *val,
const struct kernel_param *kp)
--
1.8.1
From 1c6cd63017f3c745eaf4d8705f44ba5f4af1aef7 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 14:02:09 -0400
Subject: [PATCH 19/19] hibernate: Disable in a Secure Boot environment
There is currently no way to verify the resume image when returning
from hibernate. This might compromise the secure boot trust model,
so until we can work with signed hibernate images we disable it in
a Secure Boot environment.
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
---
kernel/power/hibernate.c | 15 ++++++++++++++-
kernel/power/main.c | 7 ++++++-
kernel/power/user.c | 3 +++
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index b26f5f1..7f63cb4 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -28,6 +28,7 @@
#include <linux/syscore_ops.h>
#include <linux/ctype.h>
#include <linux/genhd.h>
+#include <linux/efi.h>
#include "power.h"
@@ -632,6 +633,10 @@ int hibernate(void)
{
int error;
+ if (!capable(CAP_COMPROMISE_KERNEL)) {
+ return -EPERM;
+ }
+
lock_system_sleep();
/* The snapshot device should not be opened while we're running */
if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
@@ -723,7 +728,7 @@ static int software_resume(void)
/*
* If the user said "noresume".. bail out early.
*/
- if (noresume)
+ if (noresume || !capable(CAP_COMPROMISE_KERNEL))
return 0;
/*
@@ -889,6 +894,11 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
int i;
char *start = buf;
+ if (efi_enabled(EFI_SECURE_BOOT)) {
+ buf += sprintf(buf, "[%s]\n", "disabled");
+ return buf-start;
+ }
+
for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
if (!hibernation_modes[i])
continue;
@@ -923,6 +933,9 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
char *p;
int mode = HIBERNATION_INVALID;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
p = memchr(buf, '\n', n);
len = p ? p - buf : n;
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 1c16f91..4f915fc 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -15,6 +15,7 @@
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
+#include <linux/efi.h>
#include "power.h"
@@ -301,7 +302,11 @@ static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
}
#endif
#ifdef CONFIG_HIBERNATION
- s += sprintf(s, "%s\n", "disk");
+ if (!efi_enabled(EFI_SECURE_BOOT)) {
+ s += sprintf(s, "%s\n", "disk");
+ } else {
+ s += sprintf(s, "\n");
+ }
#else
if (s != buf)
/* convert the last space to a newline */
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 4ed81e7..b11a0f4 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -48,6 +48,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
struct snapshot_data *data;
int error;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
lock_system_sleep();
if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
--
1.8.1
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