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kernel/secure-boot-20130218.patch
Josh Boyer b1b2d34318 Linux v3.8 
- Fix build with CONFIG_EFI disabled, reported by Peter Bowey (rhbz 911833)
- Disable debugging options.
2013-02-18 19:54:32 -05:00

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From 0c5837031a4e996877930fd023a5877dd1d615ba Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:56 -0400
Subject: [PATCH 01/19] 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)
--
1.8.1.2
From 87c8fddbcb3042fc4174b53763adbf66045a12be Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:05 -0400
Subject: [PATCH 02/19] 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 14d04e6..ed99a2d 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, "attach_queue", NULL } },
--
1.8.1.2
From df14b5319bf3ed2110839e233ac61e6136745be8 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:02 -0400
Subject: [PATCH 03/19] 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 6c72381..7dffdd5 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
--
1.8.1.2
From 49c76a665e8a09da48cbe271ea40266ca1a226c0 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:03 -0400
Subject: [PATCH 04/19] 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 | 7 +++++++
include/linux/cred.h | 2 ++
include/linux/efi.h | 1 +
6 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
index 199f453..ff651d3 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 Kernel should enable secure boot lockdowns
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/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index f8fa411..96bd86b 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -849,6 +849,36 @@ 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
@@ -1143,6 +1173,8 @@ 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 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 8b24289..d74b441 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1042,6 +1042,13 @@ void __init setup_arch(char **cmdline_p)
io_delay_init();
+ if (boot_params.secure_boot) {
+#ifdef CONFIG_EFI
+ set_bit(EFI_SECURE_BOOT, &x86_efi_facility);
+#endif
+ 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
--
1.8.1.2
From d4d1b3ad3e1a553c807b4ecafcbde4bf816e4db2 Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:30:54 -0400
Subject: [PATCH 05/19] 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:
*/
--
1.8.1.2
From 3cffca89eadf7e0f0a266c370f8034f33723831a Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:36:28 -0400
Subject: [PATCH 06/19] 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
--
1.8.1.2
From 89ea7424726ae4f7265ab84e703cf2da77acda57 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 12:36:24 -0400
Subject: [PATCH 07/19] 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))
--
1.8.1.2
From 733a5c25b896d8d5fa0051825a671911b50cb47d Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 12:42:16 -0400
Subject: [PATCH 08/19] 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);
--
1.8.1.2
From 16027d676baed34a9de804dac68d48096a688b39 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:57 -0400
Subject: [PATCH 09/19] 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);
--
1.8.1.2
From 9ff1537bbe8c22bbf7f992027da43d4fe8da0860 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:58 -0400
Subject: [PATCH 10/19] 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) {
--
1.8.1.2
From 3b27408b1ced1ec83a3ce27f9d51161dbf7cea9a Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:40:59 -0400
Subject: [PATCH 11/19] 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))
--
1.8.1.2
From fb618a04089d454b7ade68c00a2b9c7dbac013f9 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:00 -0400
Subject: [PATCH 12/19] 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);
--
1.8.1.2
From e515bbd5410d00835390fd8981aa9029e7b22b73 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Thu, 20 Sep 2012 10:41:01 -0400
Subject: [PATCH 13/19] 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);
--
1.8.1.2
From fe27dd192ef250abcbaba973a14d43b21d7be497 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Thu, 20 Sep 2012 10:41:04 -0400
Subject: [PATCH 14/19] 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
--
1.8.1.2
From c937b2c8e179bfdadb6617c0028f558e4d701e46 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Tue, 4 Sep 2012 11:55:13 -0400
Subject: [PATCH 15/19] 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;
/*
--
1.8.1.2
From f08e390045266d53543a55afa16ca4be5a1c6316 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 5 Oct 2012 10:12:48 -0400
Subject: [PATCH 16/19] 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)
--
1.8.1.2
From 54ba1eec5847d964b1d458a240b50271b9a356a4 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Fri, 26 Oct 2012 14:02:09 -0400
Subject: [PATCH 17/19] 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)) {
--
1.8.1.2
From 686090054f6c3784218b318c7adcc3c1f0ca5069 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@redhat.com>
Date: Tue, 5 Feb 2013 19:25:05 -0500
Subject: [PATCH 18/19] efi: Disable secure boot if shim is in insecure mode
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@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 96bd86b..6e1331c 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -851,8 +851,9 @@ fail:
static int get_secure_boot(efi_system_table_t *_table)
{
- 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;
@@ -876,6 +877,23 @@ static int get_secure_boot(efi_system_table_t *_table)
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_call_phys5(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;
}
--
1.8.1.2
From df607d2d5061b04f8a686cd74edd72c1f2836d8c Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Fri, 8 Feb 2013 11:12:13 -0800
Subject: [PATCH 19/19] x86: Lock down MSR writing in secure boot
Writing to MSRs should not be allowed unless CAP_COMPROMISE_KERNEL is
set since it could lead to execution of arbitrary code in kernel mode.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/kernel/msr.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 4929502..adaab3d 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -103,6 +103,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
int err = 0;
ssize_t bytes = 0;
+ if (!capable(CAP_COMPROMISE_KERNEL))
+ return -EPERM;
+
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -150,6 +153,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
err = -EBADF;
break;
}
+ if (!capable(CAP_COMPROMISE_KERNEL)) {
+ err = -EPERM;
+ break;
+ }
if (copy_from_user(&regs, uregs, sizeof regs)) {
err = -EFAULT;
break;
--
1.8.1.2
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