powerpc/pseries: define driver for Platform KeyStore

PowerVM provides an isolated Platform Keystore(PKS) storage allocation
for each LPAR with individually managed access controls to store
sensitive information securely. It provides a new set of hypervisor
calls for Linux kernel to access PKS storage.

Define POWER LPAR Platform KeyStore(PLPKS) driver using H_CALL interface
to access PKS storage.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220723113048.521744-2-nayna@linux.ibm.com

4 files changed, 545 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index f7fd91d153a4..c4a6d4083a7a 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -142,6 +142,19 @@ config IBMEBUS
 	help
 	  Bus device driver for GX bus based adapters.
 
+config PSERIES_PLPKS
+	depends on PPC_PSERIES
+	bool "Support for the Platform Key Storage"
+	help
+	  PowerVM provides an isolated Platform Keystore(PKS) storage
+	  allocation for each LPAR with individually managed access
+	  controls to store sensitive information securely. It can be
+	  used to store asymmetric public keys or secrets as required
+	  by different usecases. Select this config to enable
+	  operating system interface to hypervisor to access this space.
+
+	  If unsure, select N.
+
 config PAPR_SCM
 	depends on PPC_PSERIES && MEMORY_HOTPLUG && LIBNVDIMM
 	tristate "Support for the PAPR Storage Class Memory interface"
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 7aaff5323544..14e143b946a3 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_PAPR_SCM)		+= papr_scm.o
 obj-$(CONFIG_PPC_SPLPAR)	+= vphn.o
 obj-$(CONFIG_PPC_SVM)		+= svm.o
 obj-$(CONFIG_FA_DUMP)		+= rtas-fadump.o
+obj-$(CONFIG_PSERIES_PLPKS) += plpks.o
 
 obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PPC_VAS)		+= vas.o vas-sysfs.o
diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
new file mode 100644
index 000000000000..52aaa2894606
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/plpks.c
@@ -0,0 +1,460 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * POWER LPAR Platform KeyStore(PLPKS)
+ * Copyright (C) 2022 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ * Provides access to variables stored in Power LPAR Platform KeyStore(PLPKS).
+ */
+
+#define pr_fmt(fmt) "plpks: " fmt
+
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <asm/hvcall.h>
+
+#include "plpks.h"
+
+#define PKS_FW_OWNER	     0x1
+#define PKS_BOOTLOADER_OWNER 0x2
+#define PKS_OS_OWNER	     0x3
+
+#define LABEL_VERSION	    0
+#define MAX_LABEL_ATTR_SIZE 16
+#define MAX_NAME_SIZE	    239
+#define MAX_DATA_SIZE	    4000
+
+#define PKS_FLUSH_MAX_TIMEOUT 5000 //msec
+#define PKS_FLUSH_SLEEP	      10 //msec
+#define PKS_FLUSH_SLEEP_RANGE 400
+
+static u8 *ospassword;
+static u16 ospasswordlength;
+
+// Retrieved with H_PKS_GET_CONFIG
+static u16 maxpwsize;
+static u16 maxobjsize;
+
+struct plpks_auth {
+	u8 version;
+	u8 consumer;
+	__be64 rsvd0;
+	__be32 rsvd1;
+	__be16 passwordlength;
+	u8 password[];
+} __packed __aligned(16);
+
+struct label_attr {
+	u8 prefix[8];
+	u8 version;
+	u8 os;
+	u8 length;
+	u8 reserved[5];
+};
+
+struct label {
+	struct label_attr attr;
+	u8 name[MAX_NAME_SIZE];
+	size_t size;
+};
+
+static int pseries_status_to_err(int rc)
+{
+	int err;
+
+	switch (rc) {
+	case H_SUCCESS:
+		err = 0;
+		break;
+	case H_FUNCTION:
+		err = -ENXIO;
+		break;
+	case H_P1:
+	case H_P2:
+	case H_P3:
+	case H_P4:
+	case H_P5:
+	case H_P6:
+		err = -EINVAL;
+		break;
+	case H_NOT_FOUND:
+		err = -ENOENT;
+		break;
+	case H_BUSY:
+		err = -EBUSY;
+		break;
+	case H_AUTHORITY:
+		err = -EPERM;
+		break;
+	case H_NO_MEM:
+		err = -ENOMEM;
+		break;
+	case H_RESOURCE:
+		err = -EEXIST;
+		break;
+	case H_TOO_BIG:
+		err = -EFBIG;
+		break;
+	case H_STATE:
+		err = -EIO;
+		break;
+	case H_R_STATE:
+		err = -EIO;
+		break;
+	case H_IN_USE:
+		err = -EEXIST;
+		break;
+	case H_ABORTED:
+		err = -EINTR;
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+static int plpks_gen_password(void)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	u8 *password, consumer = PKS_OS_OWNER;
+	int rc;
+
+	password = kzalloc(maxpwsize, GFP_KERNEL);
+	if (!password)
+		return -ENOMEM;
+
+	rc = plpar_hcall(H_PKS_GEN_PASSWORD, retbuf, consumer, 0,
+			 virt_to_phys(password), maxpwsize);
+
+	if (!rc) {
+		ospasswordlength = maxpwsize;
+		ospassword = kzalloc(maxpwsize, GFP_KERNEL);
+		if (!ospassword) {
+			kfree(password);
+			return -ENOMEM;
+		}
+		memcpy(ospassword, password, ospasswordlength);
+	} else {
+		if (rc == H_IN_USE) {
+			pr_warn("Password is already set for POWER LPAR Platform KeyStore\n");
+			rc = 0;
+		} else {
+			goto out;
+		}
+	}
+out:
+	kfree(password);
+
+	return pseries_status_to_err(rc);
+}
+
+static struct plpks_auth *construct_auth(u8 consumer)
+{
+	struct plpks_auth *auth;
+
+	if (consumer > PKS_OS_OWNER)
+		return ERR_PTR(-EINVAL);
+
+	auth = kmalloc(struct_size(auth, password, maxpwsize), GFP_KERNEL);
+	if (!auth)
+		return ERR_PTR(-ENOMEM);
+
+	auth->version = 1;
+	auth->consumer = consumer;
+	auth->rsvd0 = 0;
+	auth->rsvd1 = 0;
+
+	if (consumer == PKS_FW_OWNER || consumer == PKS_BOOTLOADER_OWNER) {
+		auth->passwordlength = 0;
+		return auth;
+	}
+
+	memcpy(auth->password, ospassword, ospasswordlength);
+
+	auth->passwordlength = cpu_to_be16(ospasswordlength);
+
+	return auth;
+}
+
+/**
+ * Label is combination of label attributes + name.
+ * Label attributes are used internally by kernel and not exposed to the user.
+ */
+static struct label *construct_label(char *component, u8 varos, u8 *name,
+				     u16 namelen)
+{
+	struct label *label;
+	size_t slen;
+
+	if (!name || namelen > MAX_NAME_SIZE)
+		return ERR_PTR(-EINVAL);
+
+	slen = strlen(component);
+	if (component && slen > sizeof(label->attr.prefix))
+		return ERR_PTR(-EINVAL);
+
+	label = kzalloc(sizeof(*label), GFP_KERNEL);
+	if (!label)
+		return ERR_PTR(-ENOMEM);
+
+	if (component)
+		memcpy(&label->attr.prefix, component, slen);
+
+	label->attr.version = LABEL_VERSION;
+	label->attr.os = varos;
+	label->attr.length = MAX_LABEL_ATTR_SIZE;
+	memcpy(&label->name, name, namelen);
+
+	label->size = sizeof(struct label_attr) + namelen;
+
+	return label;
+}
+
+static int _plpks_get_config(void)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	struct {
+		u8 version;
+		u8 flags;
+		__be32 rsvd0;
+		__be16 maxpwsize;
+		__be16 maxobjlabelsize;
+		__be16 maxobjsize;
+		__be32 totalsize;
+		__be32 usedspace;
+		__be32 supportedpolicies;
+		__be64 rsvd1;
+	} __packed config;
+	size_t size;
+	int rc;
+
+	size = sizeof(config);
+
+	rc = plpar_hcall(H_PKS_GET_CONFIG, retbuf, virt_to_phys(&config), size);
+
+	if (rc != H_SUCCESS)
+		return pseries_status_to_err(rc);
+
+	maxpwsize = be16_to_cpu(config.maxpwsize);
+	maxobjsize = be16_to_cpu(config.maxobjsize);
+
+	return 0;
+}
+
+static int plpks_confirm_object_flushed(struct label *label,
+					struct plpks_auth *auth)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	u64 timeout = 0;
+	u8 status;
+	int rc;
+
+	do {
+		rc = plpar_hcall(H_PKS_CONFIRM_OBJECT_FLUSHED, retbuf,
+				 virt_to_phys(auth), virt_to_phys(label),
+				 label->size);
+
+		status = retbuf[0];
+		if (rc) {
+			if (rc == H_NOT_FOUND && status == 1)
+				rc = 0;
+			break;
+		}
+
+		if (!rc && status == 1)
+			break;
+
+		usleep_range(PKS_FLUSH_SLEEP,
+			     PKS_FLUSH_SLEEP + PKS_FLUSH_SLEEP_RANGE);
+		timeout = timeout + PKS_FLUSH_SLEEP;
+	} while (timeout < PKS_FLUSH_MAX_TIMEOUT);
+
+	rc = pseries_status_to_err(rc);
+
+	return rc;
+}
+
+int plpks_write_var(struct plpks_var var)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	struct plpks_auth *auth;
+	struct label *label;
+	int rc;
+
+	if (!var.component || !var.data || var.datalen <= 0 ||
+	    var.namelen > MAX_NAME_SIZE || var.datalen > MAX_DATA_SIZE)
+		return -EINVAL;
+
+	if (var.policy & SIGNEDUPDATE)
+		return -EINVAL;
+
+	auth = construct_auth(PKS_OS_OWNER);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	label = construct_label(var.component, var.os, var.name, var.namelen);
+	if (IS_ERR(label)) {
+		rc = PTR_ERR(label);
+		goto out;
+	}
+
+	rc = plpar_hcall(H_PKS_WRITE_OBJECT, retbuf, virt_to_phys(auth),
+			 virt_to_phys(label), label->size, var.policy,
+			 virt_to_phys(var.data), var.datalen);
+
+	if (!rc)
+		rc = plpks_confirm_object_flushed(label, auth);
+
+	if (rc)
+		pr_err("Failed to write variable %s for component %s with error %d\n",
+		       var.name, var.component, rc);
+
+	rc = pseries_status_to_err(rc);
+	kfree(label);
+out:
+	kfree(auth);
+
+	return rc;
+}
+
+int plpks_remove_var(char *component, u8 varos, struct plpks_var_name vname)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	struct plpks_auth *auth;
+	struct label *label;
+	int rc;
+
+	if (!component || vname.namelen > MAX_NAME_SIZE)
+		return -EINVAL;
+
+	auth = construct_auth(PKS_OS_OWNER);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	label = construct_label(component, varos, vname.name, vname.namelen);
+	if (IS_ERR(label)) {
+		rc = PTR_ERR(label);
+		goto out;
+	}
+
+	rc = plpar_hcall(H_PKS_REMOVE_OBJECT, retbuf, virt_to_phys(auth),
+			 virt_to_phys(label), label->size);
+
+	if (!rc)
+		rc = plpks_confirm_object_flushed(label, auth);
+
+	if (rc)
+		pr_err("Failed to remove variable %s for component %s with error %d\n",
+		       vname.name, component, rc);
+
+	rc = pseries_status_to_err(rc);
+	kfree(label);
+out:
+	kfree(auth);
+
+	return rc;
+}
+
+static int plpks_read_var(u8 consumer, struct plpks_var *var)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
+	struct plpks_auth *auth;
+	struct label *label;
+	u8 *output;
+	int rc;
+
+	if (var->namelen > MAX_NAME_SIZE)
+		return -EINVAL;
+
+	auth = construct_auth(PKS_OS_OWNER);
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
+
+	label = construct_label(var->component, var->os, var->name,
+				var->namelen);
+	if (IS_ERR(label)) {
+		rc = PTR_ERR(label);
+		goto out_free_auth;
+	}
+
+	output = kzalloc(maxobjsize, GFP_KERNEL);
+	if (!output) {
+		rc = -ENOMEM;
+		goto out_free_label;
+	}
+
+	rc = plpar_hcall(H_PKS_READ_OBJECT, retbuf, virt_to_phys(auth),
+			 virt_to_phys(label), label->size, virt_to_phys(output),
+			 maxobjsize);
+
+	if (rc != H_SUCCESS) {
+		pr_err("Failed to read variable %s for component %s with error %d\n",
+		       var->name, var->component, rc);
+		rc = pseries_status_to_err(rc);
+		goto out_free_output;
+	}
+
+	if (var->datalen == 0 || var->datalen > retbuf[0])
+		var->datalen = retbuf[0];
+
+	var->data = kzalloc(var->datalen, GFP_KERNEL);
+	if (!var->data) {
+		rc = -ENOMEM;
+		goto out_free_output;
+	}
+	var->policy = retbuf[1];
+
+	memcpy(var->data, output, var->datalen);
+	rc = 0;
+
+out_free_output:
+	kfree(output);
+out_free_label:
+	kfree(label);
+out_free_auth:
+	kfree(auth);
+
+	return rc;
+}
+
+int plpks_read_os_var(struct plpks_var *var)
+{
+	return plpks_read_var(PKS_OS_OWNER, var);
+}
+
+int plpks_read_fw_var(struct plpks_var *var)
+{
+	return plpks_read_var(PKS_FW_OWNER, var);
+}
+
+int plpks_read_bootloader_var(struct plpks_var *var)
+{
+	return plpks_read_var(PKS_BOOTLOADER_OWNER, var);
+}
+
+static __init int pseries_plpks_init(void)
+{
+	int rc;
+
+	rc = _plpks_get_config();
+
+	if (rc) {
+		pr_err("POWER LPAR Platform KeyStore is not supported or enabled\n");
+		return rc;
+	}
+
+	rc = plpks_gen_password();
+	if (rc)
+		pr_err("Failed setting POWER LPAR Platform KeyStore Password\n");
+	else
+		pr_info("POWER LPAR Platform KeyStore initialized successfully\n");
+
+	return rc;
+}
+arch_initcall(pseries_plpks_init);
diff --git a/arch/powerpc/platforms/pseries/plpks.h b/arch/powerpc/platforms/pseries/plpks.h
new file mode 100644
index 000000000000..c6a291367bb1
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/plpks.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ * Platform keystore for pseries LPAR(PLPKS).
+ */
+
+#ifndef _PSERIES_PLPKS_H
+#define _PSERIES_PLPKS_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+
+#define OSSECBOOTAUDIT 0x40000000
+#define OSSECBOOTENFORCE 0x20000000
+#define WORLDREADABLE 0x08000000
+#define SIGNEDUPDATE 0x01000000
+
+#define PLPKS_VAR_LINUX	0x01
+#define PLPKS_VAR_COMMON	0x04
+
+struct plpks_var {
+	char *component;
+	u8 *name;
+	u8 *data;
+	u32 policy;
+	u16 namelen;
+	u16 datalen;
+	u8 os;
+};
+
+struct plpks_var_name {
+	u8  *name;
+	u16 namelen;
+};
+
+struct plpks_var_name_list {
+	u32 varcount;
+	struct plpks_var_name varlist[];
+};
+
+/**
+ * Writes the specified var and its data to PKS.
+ * Any caller of PKS driver should present a valid component type for
+ * their variable.
+ */
+int plpks_write_var(struct plpks_var var);
+
+/**
+ * Removes the specified var and its data from PKS.
+ */
+int plpks_remove_var(char *component, u8 varos,
+		     struct plpks_var_name vname);
+
+/**
+ * Returns the data for the specified os variable.
+ */
+int plpks_read_os_var(struct plpks_var *var);
+
+/**
+ * Returns the data for the specified firmware variable.
+ */
+int plpks_read_fw_var(struct plpks_var *var);
+
+/**
+ * Returns the data for the specified bootloader variable.
+ */
+int plpks_read_bootloader_var(struct plpks_var *var);
+
+#endif