From 0a5e59dd7a921f20d77b13aa4e01392086ddbd12 Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:30:54 -0400
Subject: [PATCH 1/5] 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 eed2202..1da1b3c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -389,6 +389,12 @@ typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long si
#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;
@@ -524,6 +530,20 @@ 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:
*/
--
1.8.3.1
From 8b75428a7e1813cd3bc225a959e63d67898e4808 Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:36:28 -0400
Subject: [PATCH 2/5] 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 | 109 ++++++++++++++++++++++++++++++++++++
include/linux/efi.h | 4 ++
4 files changed, 122 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..424896a
--- /dev/null
+++ b/crypto/asymmetric_keys/efi_parser.c
@@ -0,0 +1,109 @@
+/* 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 |
+ KEY_ALLOC_TRUSTED);
+
+ 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 1da1b3c..42a1d25 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -619,6 +619,10 @@ extern int efi_set_rtc_mmss(const struct timespec *now);
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
--
1.8.3.1
From 920108c0f9cc5854dd329a5dfc904e91d40a4b26 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@fedoraproject.org>
Date: Fri, 26 Oct 2012 12:36:24 -0400
Subject: [PATCH 3/5] KEYS: Add a system 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@fedoraproject.org>
---
include/keys/system_keyring.h | 4 ++++
init/Kconfig | 9 +++++++++
kernel/module_signing.c | 12 ++++++++++++
kernel/system_keyring.c | 17 +++++++++++++++++
4 files changed, 42 insertions(+)
diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
index 8dabc39..e466de1 100644
--- a/include/keys/system_keyring.h
+++ b/include/keys/system_keyring.h
@@ -18,6 +18,10 @@
extern struct key *system_trusted_keyring;
+#ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
+extern struct key *system_blacklist_keyring;
+#endif
+
#endif
#endif /* _KEYS_SYSTEM_KEYRING_H */
diff --git a/init/Kconfig b/init/Kconfig
index 0ff5407..ba76e57 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1680,6 +1680,15 @@ config SYSTEM_TRUSTED_KEYRING
Keys in this keyring are used by module signature checking.
+config SYSTEM_BLACKLIST_KEYRING
+ bool "Provide system-wide ring of blacklisted keys"
+ depends on KEYS
+ help
+ Provide a system keyring to which blacklisted keys can be added. Keys
+ in the keyring are considered entirely untrusted. Keys in this keyring
+ are used by the module signature checking to reject loading of modules
+ signed with a blacklisted key.
+
menuconfig MODULES
bool "Enable loadable module support"
option modules
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 0b6b870..0a29b40 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -158,6 +158,18 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len,
pr_debug("Look up: \"%s\"\n", id);
+#ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
+ key = keyring_search(make_key_ref(system_blacklist_keyring, 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(system_trusted_keyring, 1),
&key_type_asymmetric, id);
if (IS_ERR(key))
diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
index 564dd93..389b50d 100644
--- a/kernel/system_keyring.c
+++ b/kernel/system_keyring.c
@@ -20,6 +20,9 @@
struct key *system_trusted_keyring;
EXPORT_SYMBOL_GPL(system_trusted_keyring);
+#ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
+struct key *system_blacklist_keyring;
+#endif
extern __initconst const u8 system_certificate_list[];
extern __initconst const u8 system_certificate_list_end[];
@@ -41,6 +44,20 @@ static __init int system_trusted_keyring_init(void)
panic("Can't allocate system trusted keyring\n");
set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags);
+
+#ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
+ system_blacklist_keyring = keyring_alloc(".system_blacklist_keyring",
+ 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(system_blacklist_keyring))
+ panic("Can't allocate system blacklist keyring\n");
+
+ set_bit(KEY_FLAG_TRUSTED_ONLY, &system_blacklist_keyring->flags);
+#endif
+
return 0;
}
--
1.8.3.1
From 69dca9998380c1931227a01205cdf23c34509753 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@fedoraproject.org>
Date: Fri, 26 Oct 2012 12:42:16 -0400
Subject: [PATCH 4/5] 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 system trusted 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 system blacklist keyring and forbid any module
signed with those from loading.
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
---
include/linux/efi.h | 6 ++++
init/Kconfig | 9 +++++
kernel/Makefile | 3 ++
kernel/modsign_uefi.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 110 insertions(+)
create mode 100644 kernel/modsign_uefi.c
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 42a1d25..d3e6036 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -395,6 +395,12 @@ typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long si
#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 ba76e57..b09cd98 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1799,6 +1799,15 @@ config MODULE_SIG_ALL
comment "Do not forget to sign required modules with scripts/sign-file"
depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
+config MODULE_SIG_UEFI
+ bool "Allow modules signed with certs stored in UEFI"
+ depends on MODULE_SIG && SYSTEM_BLACKLIST_KEYRING && 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 6313698..cb35a89 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_MODULE_SIG) += module_signing.o
+obj-$(CONFIG_MODULE_SIG_UEFI) += modsign_uefi.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
@@ -115,6 +116,8 @@ obj-$(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..94b0eb3
--- /dev/null
+++ b/kernel/modsign_uefi.c
@@ -0,0 +1,92 @@
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/efi.h>
+#include <linux/slab.h>
+#include <keys/asymmetric-type.h>
+#include <keys/system_keyring.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, system_trusted_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, system_trusted_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,
+ system_blacklist_keyring);
+ if (rc)
+ pr_err("Couldn't parse dbx signatures: %d\n", rc);
+ kfree(dbx);
+ }
+
+ return rc;
+}
+late_initcall(load_uefi_certs);
--
1.8.3.1
From c8e6d256ddfa2182d5b011a4ab70f8c5c9b2b590 Mon Sep 17 00:00:00 2001
From: Josh Boyer <jwboyer@fedoraproject.org>
Date: Thu, 3 Oct 2013 10:14:23 -0400
Subject: [PATCH 5/5] MODSIGN: Support not importing certs from db
If a user tells shim to not use the certs/hashes in the UEFI db variable
for verification purposes, shim will set a UEFI variable called MokIgnoreDB.
Have the uefi import code look for this and not import things from the db
variable.
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
---
kernel/modsign_uefi.c | 40 +++++++++++++++++++++++++++++++---------
1 file changed, 31 insertions(+), 9 deletions(-)
diff --git a/kernel/modsign_uefi.c b/kernel/modsign_uefi.c
index 94b0eb3..ae28b97 100644
--- a/kernel/modsign_uefi.c
+++ b/kernel/modsign_uefi.c
@@ -8,6 +8,23 @@
#include <keys/system_keyring.h>
#include "module-internal.h"
+static __init int check_ignore_db(void)
+{
+ efi_status_t status;
+ unsigned int db = 0;
+ unsigned long size = sizeof(db);
+ efi_guid_t guid = EFI_SHIM_LOCK_GUID;
+
+ /* Check and see if the MokIgnoreDB variable exists. If that fails
+ * then we don't ignore DB. If it succeeds, we do.
+ */
+ status = efi.get_variable(L"MokIgnoreDB", &guid, NULL, &size, &db);
+ if (status != EFI_SUCCESS)
+ return 0;
+
+ return 1;
+}
+
static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, unsigned long *size)
{
efi_status_t status;
@@ -47,23 +64,28 @@ static int __init load_uefi_certs(void)
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;
+ int ignore_db, rc = 0;
/* Check if SB is enabled and just return if not */
if (!efi_enabled(EFI_SECURE_BOOT))
return 0;
+ /* See if the user has setup Ignore DB mode */
+ ignore_db = check_ignore_db();
+
/* 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, system_trusted_keyring);
- if (rc)
- pr_err("Couldn't parse db signatures: %d\n", rc);
- kfree(db);
+ if (!ignore_db) {
+ 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, system_trusted_keyring);
+ if (rc)
+ pr_err("Couldn't parse db signatures: %d\n", rc);
+ kfree(db);
+ }
}
mok = get_cert_list(L"MokListRT", &mok_var, &moksize);
--
1.8.3.1