[PATCH v4 24/24] integrity/powerpc: Support loading keys from pseries secvar

[Andrew Donnellan <ajd@linux.ibm.com>]

From: Russell Currey <ruscur@russell.cc>

The secvar object format is only in the device tree under powernv.
We now have an API call to retrieve it in a generic way, so we should
use that instead of having to handle the DT here.

Add support for pseries secvar, with the "ibm,plpks-sb-v1" format.
The object format is expected to be the same, so there shouldn't be any
functional differences between objects retrieved from powernv and
pseries.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>

---

v3: New patch

v4: Pass format buffer size (stefanb, npiggin)
---
 .../integrity/platform_certs/load_powerpc.c     | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
index dee51606d5f4..d4ce91bf3fec 100644
--- a/security/integrity/platform_certs/load_powerpc.c
+++ b/security/integrity/platform_certs/load_powerpc.c
@@ -10,7 +10,6 @@
 #include <linux/cred.h>
 #include <linux/err.h>
 #include <linux/slab.h>
-#include <linux/of.h>
 #include <asm/secure_boot.h>
 #include <asm/secvar.h>
 #include "keyring_handler.h"
@@ -59,16 +58,22 @@ static int __init load_powerpc_certs(void)
 	void *db = NULL, *dbx = NULL;
 	u64 dbsize = 0, dbxsize = 0;
 	int rc = 0;
-	struct device_node *node;
+	ssize_t len;
+	char buf[32];
 
 	if (!secvar_ops)
 		return -ENODEV;
 
-	/* The following only applies for the edk2-compat backend. */
-	node = of_find_compatible_node(NULL, NULL, "ibm,edk2-compat-v1");
-	if (!node)
+	len = secvar_ops->format(buf, 32);
+	if (len <= 0)
 		return -ENODEV;
 
+	// Check for known secure boot implementations from OPAL or PLPKS
+	if (strcmp("ibm,edk2-compat-v1", buf) && strcmp("ibm,plpks-sb-v1", buf)) {
+		pr_err("Unsupported secvar implementation \"%s\", not loading certs\n", buf);
+		return -ENODEV;
+	}
+
 	/*
 	 * Get db, and dbx. They might not exist, so it isn't an error if we
 	 * can't get them.
@@ -103,8 +108,6 @@ static int __init load_powerpc_certs(void)
 		kfree(dbx);
 	}
 
-	of_node_put(node);
-
 	return rc;
 }
 late_initcall(load_powerpc_certs);
-- 
2.39.0