linux-kernel - [PATCH 2/5] powerpc/secvar: Constify 'struct bin

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Message-Id: <20241216-sysfs-const-bin_attr-powerpc-v1-2-bbed8906f476@weissschuh.net>
Date: Mon, 16 Dec 2024 05:07:44 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Michael Ellerman <mpe@...erman.id.au>, 
 Nicholas Piggin <npiggin@...il.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Naveen N Rao <naveen@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 2/5] powerpc/secvar: Constify 'struct bin_attribute'

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 arch/powerpc/kernel/secvar-sysfs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index b7536fbe8c4f43fa0f523c64685167b8b9dfd5ee..afb690a172b4e281830d0dd18785f70e0a967d13 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -52,7 +52,7 @@ static ssize_t size_show(struct kobject *kobj, struct kobj_attribute *attr,
 }
 
 static ssize_t data_read(struct file *filep, struct kobject *kobj,
-			 struct bin_attribute *attr, char *buf, loff_t off,
+			 const struct bin_attribute *attr, char *buf, loff_t off,
 			 size_t count)
 {
 	char *data;
@@ -85,7 +85,7 @@ static ssize_t data_read(struct file *filep, struct kobject *kobj,
 }
 
 static ssize_t update_write(struct file *filep, struct kobject *kobj,
-			    struct bin_attribute *attr, char *buf, loff_t off,
+			    const struct bin_attribute *attr, char *buf, loff_t off,
 			    size_t count)
 {
 	int rc;
@@ -104,11 +104,11 @@ static struct kobj_attribute format_attr = __ATTR_RO(format);
 
 static struct kobj_attribute size_attr = __ATTR_RO(size);
 
-static struct bin_attribute data_attr = __BIN_ATTR_RO(data, 0);
+static struct bin_attribute data_attr __ro_after_init = __BIN_ATTR_RO(data, 0);
 
-static struct bin_attribute update_attr = __BIN_ATTR_WO(update, 0);
+static struct bin_attribute update_attr __ro_after_init = __BIN_ATTR_WO(update, 0);
 
-static struct bin_attribute *secvar_bin_attrs[] = {
+static const struct bin_attribute *const secvar_bin_attrs[] = {
 	&data_attr,
 	&update_attr,
 	NULL,
@@ -121,7 +121,7 @@ static struct attribute *secvar_attrs[] = {
 
 static const struct attribute_group secvar_attr_group = {
 	.attrs = secvar_attrs,
-	.bin_attrs = secvar_bin_attrs,
+	.bin_attrs_new = secvar_bin_attrs,
 };
 __ATTRIBUTE_GROUPS(secvar_attr);
 

-- 
2.47.1