powerpc/pseries: PLPKS SED Opal keystore support

Define operations for SED Opal to read/write keys
from POWER LPAR Platform KeyStore(PLPKS). This allows
non-volatile storage of SED Opal keys.

Signed-off-by: Greg Joyce <[e-mail]>
Reviewed-by: Jonathan Derrick <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

arch/powerpc/platforms/pseries/Kconfig

···
 	# This option is selected by in-kernel consumers that require
 	# access to the PKS.
 
+config PSERIES_PLPKS_SED
+	depends on PPC_PSERIES
+	bool
+	# This option is selected by in-kernel consumers that require
+	# access to the SED PKS keystore.
+
 config PAPR_SCM
 	depends on PPC_PSERIES && MEMORY_HOTPLUG && LIBNVDIMM
 	tristate "Support for the PAPR Storage Class Memory interface"

arch/powerpc/platforms/pseries/Makefile

···
 obj-$(CONFIG_FA_DUMP)		+= rtas-fadump.o
 obj-$(CONFIG_PSERIES_PLPKS)	+= plpks.o
 obj-$(CONFIG_PPC_SECURE_BOOT)	+= plpks-secvar.o
+obj-$(CONFIG_PSERIES_PLPKS_SED)	+= plpks_sed_ops.o
 obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PPC_VAS)		+= vas.o vas-sysfs.o
 

arch/powerpc/platforms/pseries/plpks_sed_ops.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * POWER Platform specific code for non-volatile SED key access
+ * Copyright (C) 2022 IBM Corporation
+ *
+ * Define operations for SED Opal to read/write keys
+ * from POWER LPAR Platform KeyStore(PLPKS).
+ *
+ * Self Encrypting Drives(SED) key storage using PLPKS
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/ioctl.h>
+#include <linux/sed-opal-key.h>
+#include <asm/plpks.h>
+
+static bool plpks_sed_initialized = false;
+static bool plpks_sed_available = false;
+
+/*
+ * structure that contains all SED data
+ */
+struct plpks_sed_object_data {
+	u_char version;
+	u_char pad1[7];
+	u_long authority;
+	u_long range;
+	u_int  key_len;
+	u_char key[32];
+};
+
+#define PLPKS_SED_OBJECT_DATA_V0        0
+#define PLPKS_SED_MANGLED_LABEL         "/default/pri"
+#define PLPKS_SED_COMPONENT             "sed-opal"
+#define PLPKS_SED_KEY                   "opal-boot-pin"
+
+/*
+ * authority is admin1 and range is global
+ */
+#define PLPKS_SED_AUTHORITY  0x0000000900010001
+#define PLPKS_SED_RANGE      0x0000080200000001
+
+static void plpks_init_var(struct plpks_var *var, char *keyname)
+{
+	if (!plpks_sed_initialized) {
+		plpks_sed_initialized = true;
+		plpks_sed_available = plpks_is_available();
+		if (!plpks_sed_available)
+			pr_err("SED: plpks not available\n");
+	}
+
+	var->name = keyname;
+	var->namelen = strlen(keyname);
+	if (strcmp(PLPKS_SED_KEY, keyname) == 0) {
+		var->name = PLPKS_SED_MANGLED_LABEL;
+		var->namelen = strlen(keyname);
+	}
+	var->policy = PLPKS_WORLDREADABLE;
+	var->os = PLPKS_VAR_COMMON;
+	var->data = NULL;
+	var->datalen = 0;
+	var->component = PLPKS_SED_COMPONENT;
+}
+
+/*
+ * Read the SED Opal key from PLPKS given the label
+ */
+int sed_read_key(char *keyname, char *key, u_int *keylen)
+{
+	struct plpks_var var;
+	struct plpks_sed_object_data data;
+	int ret;
+	u_int len;
+
+	plpks_init_var(&var, keyname);
+
+	if (!plpks_sed_available)
+		return -EOPNOTSUPP;
+
+	var.data = (u8 *)&data;
+	var.datalen = sizeof(data);
+
+	ret = plpks_read_os_var(&var);
+	if (ret != 0)
+		return ret;
+
+	len = min_t(u16, be32_to_cpu(data.key_len), var.datalen);
+	memcpy(key, data.key, len);
+	key[len] = '\0';
+	*keylen = len;
+
+	return 0;
+}
+
+/*
+ * Write the SED Opal key to PLPKS given the label
+ */
+int sed_write_key(char *keyname, char *key, u_int keylen)
+{
+	struct plpks_var var;
+	struct plpks_sed_object_data data;
+	struct plpks_var_name vname;
+
+	plpks_init_var(&var, keyname);
+
+	if (!plpks_sed_available)
+		return -EOPNOTSUPP;
+
+	var.datalen = sizeof(struct plpks_sed_object_data);
+	var.data = (u8 *)&data;
+
+	/* initialize SED object */
+	data.version = PLPKS_SED_OBJECT_DATA_V0;
+	data.authority = cpu_to_be64(PLPKS_SED_AUTHORITY);
+	data.range = cpu_to_be64(PLPKS_SED_RANGE);
+	memset(&data.pad1, '\0', sizeof(data.pad1));
+	data.key_len = cpu_to_be32(keylen);
+	memcpy(data.key, (char *)key, keylen);
+
+	/*
+	 * Key update requires remove first. The return value
+	 * is ignored since it's okay if the key doesn't exist.
+	 */
+	vname.namelen = var.namelen;
+	vname.name = var.name;
+	plpks_remove_var(var.component, var.os, vname);
+
+	return plpks_write_var(var);
+}

block/Kconfig

···
 	bool "Logic for interfacing with Opal enabled SEDs"
 	depends on KEYS
 	select PSERIES_PLPKS if PPC_PSERIES
+	select PSERIES_PLPKS_SED if PPC_PSERIES
 	help
 	Builds Logic for interfacing with Opal enabled controllers.
 	Enabling this option enables users to setup/unlock/lock