[PATCH v2 0/3] powerpc: Enabling secure boot on powernv systems - Part 1

[PATCH v2 0/3] powerpc: Enabling secure boot on powernv systems - Part 1

[Nayna Jain]

This patch set is part of a series that implements secure boot on PowerNV
systems.

In order to verify the OS kernel on PowerNV, secure boot requires X.509
certificates trusted by the platform, the secure boot modes, and several
other pieces of information. These are stored in secure variables
controlled by OPAL, also known as OPAL secure variables.

The IMA architecture specific policy support on Power is dependent on OPAL
runtime services to access secure variables. Instead of directly accessing
the OPAL runtime services, version 1[1] of this patch set relied upon the
EFI hooks. This version drops that dependency and calls the OPAL runtime
services directly.

Exposing the OPAL secure variables to userspace will be posted as a
separate patch set, allowing the IMA architecture specific policy on Power
to be upstreamed independently.

This patch set adds the following features:

1. Add support for OPAL Runtime API to access secure variables controlled
by OPAL.
2. Define IMA arch-specific policies based on the secure boot state and
mode of the system. On secure boot enabled powernv systems, the OS kernel
signature will be verified by IMA appraisal.

[1] https://patchwork.kernel.org/cover/10882149/

Changelog:

v2:

* Removed Patch 1: powerpc/include: Override unneeded early ioremap
functions
* Updated Subject line and patch description of the Patch 1 of this series
* Removed dependency of OPAL_SECVAR on EFI, CPU_BIG_ENDIAN and UCS2_STRING
* Changed OPAL APIs from static to non-static. Added opal-secvar.h for the
same
* Removed EFI hooks from opal_secvar.c 
* Removed opal_secvar_get_next(), opal_secvar_enqueue() and
opal_query_variable_info() function
* get_powerpc_sb_mode() in secboot.c now directly calls OPAL Runtime API
rather than via EFI hooks.
* Fixed log messages in get_powerpc_sb_mode() function.
* Added dependency for PPC_SECURE_BOOT on configs PPC64 and OPAL_SECVAR
* Replaced obj-$(CONFIG_IMA) with obj-$(CONFIG_PPC_SECURE_BOOT) in
arch/powerpc/kernel/Makefile

Claudio Carvalho (1):
  powerpc/powernv: Add support for OPAL_SECVAR_GET

Nayna Jain (2):
  powerpc/powernv: detect the secure boot mode of the system
  powerpc: Add support to initialize ima policy rules

 arch/powerpc/Kconfig                         |  14 +++
 arch/powerpc/include/asm/opal-api.h          |   3 +-
 arch/powerpc/include/asm/opal-secvar.h       |  18 ++++
 arch/powerpc/include/asm/opal.h              |   2 +
 arch/powerpc/include/asm/secboot.h           |  21 ++++
 arch/powerpc/kernel/Makefile                 |   1 +
 arch/powerpc/kernel/ima_arch.c               |  54 ++++++++++
 arch/powerpc/platforms/powernv/Kconfig       |   6 ++
 arch/powerpc/platforms/powernv/Makefile      |   2 +
 arch/powerpc/platforms/powernv/opal-call.c   |   1 +
 arch/powerpc/platforms/powernv/opal-secvar.c | 107 +++++++++++++++++++
 arch/powerpc/platforms/powernv/secboot.c     |  54 ++++++++++
 include/linux/ima.h                          |   3 +-
 13 files changed, 284 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/include/asm/opal-secvar.h
 create mode 100644 arch/powerpc/include/asm/secboot.h
 create mode 100644 arch/powerpc/kernel/ima_arch.c
 create mode 100644 arch/powerpc/platforms/powernv/opal-secvar.c
 create mode 100644 arch/powerpc/platforms/powernv/secboot.c

-- 
2.20.1

[PATCH v2 1/3] powerpc/powernv: Add support for OPAL_SECVAR_GET

[Nayna Jain]

From: Claudio Carvalho <cclaudio@linux.ibm.com>

The X.509 certificates trusted by the platform and other information
required to secure boot the OS kernel are wrapped in secure variables,
which are controlled by OPAL.

This patch adds support to read OPAL secure variables through
OPAL_SECVAR_GET call. It returns the data for a given secure variable
and vendor GUID. It can be configured using CONFIG_OPAL_SECVAR.

Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>

---
This patch depends on a new OPAL call that is being added to skiboot.
The patch set that implements the new call has been posted to
https://patchwork.ozlabs.org/project/skiboot/list/?series=99805
---
 arch/powerpc/include/asm/opal-api.h          |   3 +-
 arch/powerpc/include/asm/opal-secvar.h       |  18 ++++
 arch/powerpc/include/asm/opal.h              |   2 +
 arch/powerpc/platforms/powernv/Kconfig       |   6 ++
 arch/powerpc/platforms/powernv/Makefile      |   1 +
 arch/powerpc/platforms/powernv/opal-call.c   |   1 +
 arch/powerpc/platforms/powernv/opal-secvar.c | 107 +++++++++++++++++++
 7 files changed, 137 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/include/asm/opal-secvar.h
 create mode 100644 arch/powerpc/platforms/powernv/opal-secvar.c

diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index 870fb7b239ea..782eb20a08a7 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -210,7 +210,8 @@
 #define OPAL_PCI_GET_PBCQ_TUNNEL_BAR		164
 #define OPAL_PCI_SET_PBCQ_TUNNEL_BAR		165
 #define	OPAL_NX_COPROC_INIT			167
-#define OPAL_LAST				167
+#define OPAL_SECVAR_GET				170
+#define OPAL_LAST				171
 
 #define QUIESCE_HOLD			1 /* Spin all calls at entry */
 #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */
diff --git a/arch/powerpc/include/asm/opal-secvar.h b/arch/powerpc/include/asm/opal-secvar.h
new file mode 100644
index 000000000000..e3d5e4cbf3bc
--- /dev/null
+++ b/arch/powerpc/include/asm/opal-secvar.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PowerNV definitions for secure variables OPAL API.
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Claudio Carvalho <cclaudio@linux.ibm.com>
+ *
+ */
+#ifndef OPAL_SECVAR_H
+#define OPAL_SECVAR_H
+
+#include <linux/efi.h>
+
+extern efi_status_t
+opal_get_variable(efi_char16_t *name, efi_guid_t *vendor, u32 *attr,
+		  unsigned long *data_size, void *data);
+
+#endif
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index a55b01c90bb1..eb654baf8764 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -385,6 +385,8 @@ void opal_powercap_init(void);
 void opal_psr_init(void);
 void opal_sensor_groups_init(void);
 
+extern int opal_secvar_get(uint64_t name, uint64_t vendor, uint64_t attr,
+			   uint64_t data_size, uint64_t data);
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_OPAL_H */
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index 850eee860cf2..65b060539b5c 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -47,3 +47,9 @@ config PPC_VAS
 	  VAS adapters are found in POWER9 based systems.
 
 	  If unsure, say N.
+
+config OPAL_SECVAR
+	bool "OPAL Secure Variables"
+	depends on PPC_POWERNV
+	help
+	  This enables the kernel to access OPAL secure variables.
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index da2e99efbd04..1511d836fd19 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_PERF_EVENTS) += opal-imc.o
 obj-$(CONFIG_PPC_MEMTRACE)	+= memtrace.o
 obj-$(CONFIG_PPC_VAS)	+= vas.o vas-window.o vas-debug.o
 obj-$(CONFIG_OCXL_BASE)	+= ocxl.o
+obj-$(CONFIG_OPAL_SECVAR)	+= opal-secvar.o
diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
index daad8c45c8e7..eafd8f690b7a 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -282,3 +282,4 @@ OPAL_CALL(opal_pci_set_pbcq_tunnel_bar,		OPAL_PCI_SET_PBCQ_TUNNEL_BAR);
 OPAL_CALL(opal_sensor_read_u64,			OPAL_SENSOR_READ_U64);
 OPAL_CALL(opal_sensor_group_enable,		OPAL_SENSOR_GROUP_ENABLE);
 OPAL_CALL(opal_nx_coproc_init,			OPAL_NX_COPROC_INIT);
+OPAL_CALL(opal_secvar_get,			OPAL_SECVAR_GET);
diff --git a/arch/powerpc/platforms/powernv/opal-secvar.c b/arch/powerpc/platforms/powernv/opal-secvar.c
new file mode 100644
index 000000000000..3ba02c9503f7
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-secvar.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PowerNV code for secure variables
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Claudio Carvalho <cclaudio@linux.ibm.com>
+ *
+ */
+
+/*
+ * The opal wrappers in this file treat the @name, @vendor, and @data
+ * parameters as little endian blobs.
+ * @name is a ucs2 string
+ * @vendor is the vendor GUID. It is converted to LE in the kernel
+ * @data variable data, which layout may be different for each variable
+ */
+
+#define pr_fmt(fmt) "secvar: "fmt
+
+#include <linux/efi.h>
+#include <asm/machdep.h>
+#include <asm/opal.h>
+#include <asm/opal-secvar.h>
+
+static bool is_opal_secvar_supported(void)
+{
+	static bool opal_secvar_supported;
+	static bool initialized;
+
+	if (initialized)
+		return opal_secvar_supported;
+
+	if (opal_check_token(OPAL_SECVAR_GET))
+		opal_secvar_supported = true;
+	else
+		opal_secvar_supported = false;
+
+	initialized = true;
+
+	return opal_secvar_supported;
+}
+
+efi_status_t opal_to_efi_status_log(int rc, const char *func_name)
+{
+	efi_status_t status;
+
+	switch (rc) {
+	case OPAL_EMPTY:
+		status = EFI_NOT_FOUND;
+		break;
+	case OPAL_HARDWARE:
+		status = EFI_DEVICE_ERROR;
+		break;
+	case OPAL_NO_MEM:
+		pr_err("%s: No space in the volatile storage\n", func_name);
+		status = EFI_OUT_OF_RESOURCES;
+		break;
+	case OPAL_PARAMETER:
+		status = EFI_INVALID_PARAMETER;
+		break;
+	case OPAL_PARTIAL:
+		status = EFI_BUFFER_TOO_SMALL;
+		break;
+	case OPAL_PERMISSION:
+		status = EFI_WRITE_PROTECTED;
+		break;
+	case OPAL_RESOURCE:
+		pr_err("%s: No space in the non-volatile storage\n", func_name);
+		status = EFI_OUT_OF_RESOURCES;
+		break;
+	case OPAL_SUCCESS:
+		status = EFI_SUCCESS;
+		break;
+	default:
+		pr_err("%s: Unknown OPAL error %d\n", func_name, rc);
+		status = EFI_DEVICE_ERROR;
+		break;
+	}
+
+	return status;
+}
+
+#define opal_to_efi_status(rc) opal_to_efi_status_log(rc, __func__)
+
+efi_status_t
+opal_get_variable(efi_char16_t *name, efi_guid_t *vendor, u32 *attr,
+		  unsigned long *data_size, void *data)
+{
+	int rc;
+
+	if (!is_opal_secvar_supported())
+		return EFI_UNSUPPORTED;
+
+	*data_size = cpu_to_be64(*data_size);
+
+	rc = opal_secvar_get(__pa(name), __pa(vendor), __pa(attr),
+			     __pa(data_size), __pa(data));
+	/*
+	 * The @attr is an optional output parameter. It is returned in
+	 * big-endian.
+	 */
+	if (attr)
+		*attr = be32_to_cpup(attr);
+	*data_size = be64_to_cpu(*data_size);
+
+	return opal_to_efi_status(rc);
+}
-- 
2.20.1

[PATCH v2 2/3] powerpc/powernv: detect the secure boot mode of the system

[Nayna Jain]

PowerNV secure boot defines different IMA policies based on the secure
boot state of the system.

This patch defines a function to detect the secure boot state of the
system.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
---
 arch/powerpc/include/asm/secboot.h       | 21 +++++++++
 arch/powerpc/platforms/powernv/Makefile  |  3 +-
 arch/powerpc/platforms/powernv/secboot.c | 54 ++++++++++++++++++++++++
 3 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/include/asm/secboot.h
 create mode 100644 arch/powerpc/platforms/powernv/secboot.c

diff --git a/arch/powerpc/include/asm/secboot.h b/arch/powerpc/include/asm/secboot.h
new file mode 100644
index 000000000000..1904fb4a3352
--- /dev/null
+++ b/arch/powerpc/include/asm/secboot.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PowerPC secure boot definitions
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ */
+#ifndef POWERPC_SECBOOT_H
+#define POWERPC_SECBOOT_H
+
+#if defined(CONFIG_OPAL_SECVAR)
+extern bool get_powerpc_sb_mode(void);
+#else
+static inline bool get_powerpc_sb_mode(void)
+{
+	return false;
+}
+#endif
+
+#endif
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index 1511d836fd19..e3224f1019eb 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -4,6 +4,7 @@ obj-y			+= idle.o opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
 obj-y			+= rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
 obj-y			+= opal-msglog.o opal-hmi.o opal-power.o opal-irqchip.o
 obj-y			+= opal-kmsg.o opal-powercap.o opal-psr.o opal-sensor-groups.o
+obj-y			+= secboot.o
 
 obj-$(CONFIG_SMP)	+= smp.o subcore.o subcore-asm.o
 obj-$(CONFIG_PCI)	+= pci.o pci-ioda.o npu-dma.o pci-ioda-tce.o
@@ -16,4 +17,4 @@ obj-$(CONFIG_PERF_EVENTS) += opal-imc.o
 obj-$(CONFIG_PPC_MEMTRACE)	+= memtrace.o
 obj-$(CONFIG_PPC_VAS)	+= vas.o vas-window.o vas-debug.o
 obj-$(CONFIG_OCXL_BASE)	+= ocxl.o
-obj-$(CONFIG_OPAL_SECVAR)	+= opal-secvar.o
+obj-$(CONFIG_OPAL_SECVAR)	+= opal-secvar.o secboot.o
diff --git a/arch/powerpc/platforms/powernv/secboot.c b/arch/powerpc/platforms/powernv/secboot.c
new file mode 100644
index 000000000000..a9c5717bb78e
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/secboot.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ * secboot.c
+ *      - util functions to get powerpc secboot state
+ */
+#include <linux/efi.h>
+#include <asm/secboot.h>
+#include <asm/opal-secvar.h>
+
+bool get_powerpc_sb_mode(void)
+{
+	efi_char16_t efi_SecureBoot_name[] = L"SecureBoot";
+	efi_char16_t efi_SetupMode_name[] = L"SetupMode";
+	efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
+	efi_status_t status;
+	u8 secboot, setupmode;
+	unsigned long size = sizeof(secboot);
+
+	status = opal_get_variable(efi_SecureBoot_name, &efi_variable_guid,
+				  NULL, &size, &secboot);
+
+	/*
+	 * For now assume all failures reading the SecureBoot variable implies
+	 * secure boot is not enabled. Later differentiate failure types.
+	 */
+	if (status != EFI_SUCCESS) {
+		secboot = 0;
+		setupmode = 0;
+		goto out;
+	}
+
+	size = sizeof(setupmode);
+	status = opal_get_variable(efi_SetupMode_name, &efi_variable_guid,
+				  NULL, &size, &setupmode);
+
+	/*
+	 * Failure to read the SetupMode variable does not prevent
+	 * secure boot mode
+	 */
+	if (status != EFI_SUCCESS)
+		setupmode = 0;
+
+out:
+	if ((secboot == 0) || (setupmode == 1)) {
+		pr_info("secboot: secureboot mode disabled\n");
+		return false;
+	}
+
+	pr_info("secboot: secureboot mode enabled\n");
+	return true;
+}
-- 
2.20.1

[PATCH v2 3/3] powerpc: Add support to initialize ima policy rules

[Nayna Jain]

PowerNV secure boot relies on the kernel IMA security subsystem to
perform the OS kernel image signature verification. Since each secure
boot mode has different IMA policy requirements, dynamic definition of
the policy rules based on the runtime secure boot mode of the system is
required. On systems that support secure boot, but have it disabled,
only measurement policy rules of the kernel image and modules are
defined.

This patch defines the arch-specific implementation to retrieve the
secure boot mode of the system and accordingly configures the IMA policy
rules.

This patch provides arch-specific IMA policies if PPC_SECURE_BOOT
config is enabled.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
---
 arch/powerpc/Kconfig           | 14 +++++++++
 arch/powerpc/kernel/Makefile   |  1 +
 arch/powerpc/kernel/ima_arch.c | 54 ++++++++++++++++++++++++++++++++++
 include/linux/ima.h            |  3 +-
 4 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/kernel/ima_arch.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2d0be82c3061..7407af79ed8a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -901,6 +901,20 @@ config PPC_MEM_KEYS
 
 	  If unsure, say y.
 
+config PPC_SECURE_BOOT
+	prompt "Enable PowerPC Secure Boot"
+	bool
+	default n
+	depends on PPC64
+	depends on OPAL_SECVAR
+	depends on IMA
+	depends on IMA_ARCH_POLICY
+	help
+	  Linux on POWER with firmware secure boot enabled needs to define
+	  security policies to extend secure boot to the OS.
+	  This config allows user to enable OS Secure Boot on PowerPC systems
+	  that have firmware secure boot support.
+
 endmenu
 
 config ISA_DMA_API
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index cddadccf551d..fcbc7a94888b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -119,6 +119,7 @@ ifdef CONFIG_IMA
 obj-y				+= ima_kexec.o
 endif
 endif
+obj-$(CONFIG_PPC_SECURE_BOOT)	+= ima_arch.o
 
 obj-$(CONFIG_AUDIT)		+= audit.o
 obj64-$(CONFIG_AUDIT)		+= compat_audit.o
diff --git a/arch/powerpc/kernel/ima_arch.c b/arch/powerpc/kernel/ima_arch.c
new file mode 100644
index 000000000000..871b321656fb
--- /dev/null
+++ b/arch/powerpc/kernel/ima_arch.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ * ima_arch.c
+ *      - initialize ima policies for PowerPC Secure Boot
+ */
+
+#include <linux/ima.h>
+#include <asm/secboot.h>
+
+bool arch_ima_get_secureboot(void)
+{
+	bool sb_mode;
+
+	sb_mode = get_powerpc_sb_mode();
+	if (sb_mode)
+		return true;
+	else
+		return false;
+}
+
+/*
+ * File signature verification is not needed, include only measurements
+ */
+static const char *const default_arch_rules[] = {
+	"measure func=KEXEC_KERNEL_CHECK",
+	"measure func=MODULE_CHECK",
+	NULL
+};
+
+/* Both file signature verification and measurements are needed */
+static const char *const sb_arch_rules[] = {
+	"measure func=KEXEC_KERNEL_CHECK",
+	"measure func=MODULE_CHECK",
+	"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
+#if !IS_ENABLED(CONFIG_MODULE_SIG)
+	"appraise func=MODULE_CHECK appraise_type=imasig",
+#endif
+	NULL
+};
+
+/*
+ * On PowerPC, file measurements are to be added to the IMA measurement list
+ * irrespective of the secure boot state of the system. Signature verification
+ * is conditionally enabled based on the secure boot state.
+ */
+const char *const *arch_get_ima_policy(void)
+{
+	if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot())
+		return sb_arch_rules;
+	return default_arch_rules;
+}
diff --git a/include/linux/ima.h b/include/linux/ima.h
index dc12fbcf484c..ab81a204cf4c 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -31,7 +31,8 @@ extern void ima_post_path_mknod(struct dentry *dentry);
 extern void ima_add_kexec_buffer(struct kimage *image);
 #endif
 
-#if defined(CONFIG_X86) && defined(CONFIG_EFI)
+#if (defined(CONFIG_X86) && defined(CONFIG_EFI)) \
+			 || defined(CONFIG_PPC_SECURE_BOOT)
 extern bool arch_ima_get_secureboot(void);
 extern const char * const *arch_get_ima_policy(void);
 #else
-- 
2.20.1