linux-kernel - [PATCH v5 10/25] powerpc/secvar: Extend sysfs to include config vars

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Date:   Tue, 31 Jan 2023 17:39:13 +1100
From:   Andrew Donnellan <ajd@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-integrity@...r.kernel.org
Cc:     ruscur@...sell.cc, bgray@...ux.ibm.com, nayna@...ux.ibm.com,
        gcwilson@...ux.ibm.com, gjoyce@...ux.ibm.com, brking@...ux.ibm.com,
        stefanb@...ux.ibm.com, sudhakar@...ux.ibm.com,
        erichte@...ux.ibm.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, zohar@...ux.ibm.com, joel@....id.au,
        npiggin@...il.com
Subject: [PATCH v5 10/25] powerpc/secvar: Extend sysfs to include config vars

From: Russell Currey <ruscur@...sell.cc>

The forthcoming pseries consumer of the secvar API wants to expose a
number of config variables.  Allowing secvar implementations to provide
their own sysfs attributes makes it easy for consumers to expose what
they need to.

This is not being used by the OPAL secvar implementation at present, and
the config directory will not be created if no attributes are set.

Signed-off-by: Russell Currey <ruscur@...sell.cc>
Co-developed-by: Andrew Donnellan <ajd@...ux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@...ux.ibm.com>

---

v3: Remove unnecessary "secvar:" prefix from error messages (ajd)

    Merge config attributes into secvar_operations (mpe)
---
 arch/powerpc/include/asm/secvar.h  |  2 ++
 arch/powerpc/kernel/secvar-sysfs.c | 33 +++++++++++++++++++++++++-----
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index bf396215903d..011a53a8076c 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h
@@ -10,6 +10,7 @@
 
 #include <linux/types.h>
 #include <linux/errno.h>
+#include <linux/sysfs.h>
 
 extern const struct secvar_operations *secvar_ops;
 
@@ -19,6 +20,7 @@ struct secvar_operations {
 	int (*set)(const char *key, u64 key_len, u8 *data, u64 data_size);
 	ssize_t (*format)(char *buf, size_t bufsize);
 	int (*max_size)(u64 *max_size);
+	const struct attribute **config_attrs;
 };
 
 #ifdef CONFIG_PPC_SECURE_BOOT
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index 8f3deff94009..7df32be86507 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -144,6 +144,19 @@ static int update_kobj_size(void)
 	return 0;
 }
 
+static int secvar_sysfs_config(struct kobject *kobj)
+{
+	struct attribute_group config_group = {
+		.name = "config",
+		.attrs = (struct attribute **)secvar_ops->config_attrs,
+	};
+
+	if (secvar_ops->config_attrs)
+		return sysfs_create_group(kobj, &config_group);
+
+	return 0;
+}
+
 static int secvar_sysfs_load(void)
 {
 	struct kobject *kobj;
@@ -208,26 +221,36 @@ static int secvar_sysfs_init(void)
 
 	rc = sysfs_create_file(secvar_kobj, &format_attr.attr);
 	if (rc) {
-		kobject_put(secvar_kobj);
-		return -ENOMEM;
+		pr_err("Failed to create format object\n");
+		rc = -ENOMEM;
+		goto err;
 	}
 
 	secvar_kset = kset_create_and_add("vars", NULL, secvar_kobj);
 	if (!secvar_kset) {
 		pr_err("sysfs kobject registration failed\n");
-		kobject_put(secvar_kobj);
-		return -ENOMEM;
+		rc = -ENOMEM;
+		goto err;
 	}
 
 	rc = update_kobj_size();
 	if (rc) {
 		pr_err("Cannot read the size of the attribute\n");
-		return rc;
+		goto err;
+	}
+
+	rc = secvar_sysfs_config(secvar_kobj);
+	if (rc) {
+		pr_err("Failed to create config directory\n");
+		goto err;
 	}
 
 	secvar_sysfs_load();
 
 	return 0;
+err:
+	kobject_put(secvar_kobj);
+	return rc;
 }
 
 late_initcall(secvar_sysfs_init);
-- 
2.39.1