2019-10-24 19:10:44

by Nayna Jain

Subject: [PATCH v9 3/8] powerpc: detect the trusted boot state of the system

While secure boot permits only properly verified signed kernels to be
booted, trusted boot calculates the file hash of the kernel image and
stores the measurement prior to boot, that can be subsequently compared
against good known values via attestation services.

This patch reads the trusted boot state of a PowerNV system. The state
is used to conditionally enable additional measurement rules in the IMA
arch-specific policies.

Signed-off-by: Nayna Jain <[email protected]>
---
arch/powerpc/include/asm/secure_boot.h | 6 ++++++
arch/powerpc/kernel/secure_boot.c | 26 ++++++++++++++++++++++++++
2 files changed, 32 insertions(+)

diff --git a/arch/powerpc/include/asm/secure_boot.h b/arch/powerpc/include/asm/secure_boot.h
index 07d0fe0ca81f..a2ff556916c6 100644
--- a/arch/powerpc/include/asm/secure_boot.h
+++ b/arch/powerpc/include/asm/secure_boot.h
@@ -11,6 +11,7 @@
#ifdef CONFIG_PPC_SECURE_BOOT

bool is_ppc_secureboot_enabled(void);
+bool is_ppc_trustedboot_enabled(void);

#else

@@ -19,5 +20,10 @@ static inline bool is_ppc_secureboot_enabled(void)
return false;
}

+static inline bool is_ppc_trustedboot_enabled(void)
+{
+ return false;
+}
+
#endif
#endif
diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
index 63dc82c50862..a6a5f17ede03 100644
--- a/arch/powerpc/kernel/secure_boot.c
+++ b/arch/powerpc/kernel/secure_boot.c
@@ -7,6 +7,17 @@
#include <linux/of.h>
#include <asm/secure_boot.h>

+static struct device_node *get_ppc_fw_sb_node(void)
+{
+ static const struct of_device_id ids[] = {
+ { .compatible = "ibm,secureboot-v1", },
+ { .compatible = "ibm,secureboot-v2", },
+ {},
+ };
+
+ return of_find_matching_node(NULL, ids);
+}
+
bool is_ppc_secureboot_enabled(void)
{
struct device_node *node;
@@ -30,3 +41,18 @@ bool is_ppc_secureboot_enabled(void)
pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
return enabled;
}
+
+bool is_ppc_trustedboot_enabled(void)
+{
+ struct device_node *node;
+ bool enabled = false;
+
+ node = get_ppc_fw_sb_node();
+ enabled = of_property_read_bool(node, "trusted-enabled");
+
+ of_node_put(node);
+
+ pr_info("Trusted boot mode %s\n", enabled ? "enabled" : "disabled");
+
+ return enabled;
+}
--
2.20.1

2019-10-25 18:47:18

by Lakshmi Ramasubramanian

Subject: Re: [PATCH v9 3/8] powerpc: detect the trusted boot state of the system

On 10/23/2019 8:47 PM, Nayna Jain wrote:

> +bool is_ppc_trustedboot_enabled(void)
> +{
> + struct device_node *node;
> + bool enabled = false;
> +
> + node = get_ppc_fw_sb_node();
> + enabled = of_property_read_bool(node, "trusted-enabled");

Can get_ppc_fw_sb_node return NULL?
Would of_property_read_bool handle the case when node is NULL?

-lakshmi

2019-10-25 20:47:49

by Nayna Jain

Subject: Re: [PATCH v9 3/8] powerpc: detect the trusted boot state of the system

On 10/24/19 12:38 PM, Lakshmi Ramasubramanian wrote:
> On 10/23/2019 8:47 PM, Nayna Jain wrote:
>
>> +bool is_ppc_trustedboot_enabled(void)
>> +{
>> +    struct device_node *node;
>> +    bool enabled = false;
>> +
>> +    node = get_ppc_fw_sb_node();
>> +    enabled = of_property_read_bool(node, "trusted-enabled");
>
> Can get_ppc_fw_sb_node return NULL?
> Would of_property_read_bool handle the case when node is NULL?

Yes.

Thanks & Regards,

     - Nayna