linux-kernel - [PATCH v10a 3/9] powerpc: detect the trusted boot state of the system

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Message-Id: <e9eeee6b-b9bf-1e41-2954-61dbd6fbfbcf@linux.ibm.com>
Date:   Tue, 5 Nov 2019 17:02:07 -0600
From:   Eric Richter <erichte@...ux.ibm.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, linuxppc-dev@...abs.org,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     Nayna Jain <nayna@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Kerr <jk@...abs.org>,
        "Oliver O'Halloran" <oohall@...il.com>
Subject: [PATCH v10a 3/9] powerpc: detect the trusted boot state of the system

From: Nayna Jain <nayna@...ux.ibm.com>

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 <nayna@...ux.ibm.com>
Signed-off-by: Eric Richter <erichte@...ux.ibm.com>
---
v10a:
- moved get_ppc_fw_sb_node to patch 1 in the series

 arch/powerpc/include/asm/secure_boot.h |  6 ++++++
 arch/powerpc/kernel/secure_boot.c      | 15 +++++++++++++++
 2 files changed, 21 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 3f55be33f5c8..95d2ff086e55 100644
--- a/arch/powerpc/kernel/secure_boot.c
+++ b/arch/powerpc/kernel/secure_boot.c
@@ -32,3 +32,18 @@ bool is_ppc_secureboot_enabled(void)
 
 	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