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SubjectRe: [PATCH v3 3/3] powerpc: Add support to initialize ima policy rules
On Mon, Jun 10, 2019 at 04:33:57PM -0400, Nayna Jain wrote:
> 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

Hi,

This series failed to build against linuxppc/merge tree with `ppc64le_defconfig`,

arch/powerpc/platforms/powernv/secboot.c:14:6: error: redefinition of 'get_powerpc_sb_mode'
14 | bool get_powerpc_sb_mode(void)
| ^~~~~~~~~~~~~~~~~~~
In file included from arch/powerpc/platforms/powernv/secboot.c:11:
./arch/powerpc/include/asm/secboot.h:15:20: note: previous definition of 'get_powerpc_sb_mode' was here
15 | static inline bool get_powerpc_sb_mode(void)
| ^~~~~~~~~~~~~~~~~~~
make[3]: *** [scripts/Makefile.build:278: arch/powerpc/platforms/powernv/secboot.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [scripts/Makefile.build:489: arch/powerpc/platforms/powernv] Error 2
make[1]: *** [scripts/Makefile.build:489: arch/powerpc/platforms] Error 2
make: *** [Makefile:1071: arch/powerpc] Error 2
make: *** Waiting for unfinished jobs....

Regards,
-Satheesh

>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 8c1c636308c8..9de77bb14f54 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -902,6 +902,20 @@ 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 0ea6c4aa3a20..75c929b41341 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -131,6 +131,7 @@ 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..1767bf6e6550
> --- /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 template=ima-modsig",
> + "measure func=MODULE_CHECK template=ima-modsig",
> + NULL
> +};
> +
> +/* Both file signature verification and measurements are needed */
> +static const char *const sb_arch_rules[] = {
> + "measure func=KEXEC_KERNEL_CHECK template=ima-modsig",
> + "measure func=MODULE_CHECK template=ima-modsig",
> + "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig template=ima-modsig",
> +#if !IS_ENABLED(CONFIG_MODULE_SIG)
> + "appraise func=MODULE_CHECK appraise_type=imasig|modsig template=ima-modsig",
> +#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 fd9f7cf4cdf5..a01df076ecae 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)) || defined(CONFIG_S390)
> +#if (defined(CONFIG_X86) && defined(CONFIG_EFI)) || defined(CONFIG_S390) \
> + || 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
>

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