[PATCH v3 04/24] powerpc/secvar: Handle format string in the consumer

Andrew Donnellan
2023-01-18T06:34:22Z

From: Russell Currey <ruscur@russell.cc>

The code that handles the format string in secvar-sysfs.c is entirely
OPAL specific, so create a new "format" op in secvar_operations to make
the secvar code more generic. No functional change.

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

---

v2: Use sysfs_emit() instead of sprintf() (gregkh)

v3: Enforce format string size limit (ruscur)
---
arch/powerpc/include/asm/secvar.h | 3 +++
arch/powerpc/kernel/secvar-sysfs.c | 23 ++++--------------
arch/powerpc/platforms/powernv/opal-secvar.c | 25 ++++++++++++++++++++
3 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index 07ba36f868a7..8b6475589120 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h
@@ -11,12 +11,15 @@
#include <linux/types.h>
#include <linux/errno.h>

+#define SECVAR_MAX_FORMAT_LEN 30 // max length of string returned by ->format()
+
extern const struct secvar_operations *secvar_ops;

struct secvar_operations {
int (*get)(const char *key, u64 key_len, u8 *data, u64 *data_size);
int (*get_next)(const char *key, u64 *key_len, u64 keybufsize);
int (*set)(const char *key, u64 key_len, u8 *data, u64 data_size);
+ ssize_t (*format)(char *buf);
};

#ifdef CONFIG_PPC_SECURE_BOOT
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index 462cacc0ca60..d3858eedd72c 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -21,26 +21,13 @@ static struct kset *secvar_kset;
static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
- ssize_t rc = 0;
- struct device_node *node;
- const char *format;
-
- node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
- if (!of_device_is_available(node)) {
- rc = -ENODEV;
- goto out;
- }
+ char tmp[SECVAR_MAX_FORMAT_LEN];
+ ssize_t len = secvar_ops->format(tmp);

- rc = of_property_read_string(node, "format", &format);
- if (rc)
- goto out;
+ if (len <= 0)
+ return -EIO;

- rc = sysfs_emit(buf, "%s\n", format);
-
-out:
- of_node_put(node);
-
- return rc;
+ return sysfs_emit(buf, "%s\n", tmp);
}

diff --git a/arch/powerpc/platforms/powernv/opal-secvar.c b/arch/powerpc/platforms/powernv/opal-secvar.c
index ef89861569e0..623c6839e66c 100644
--- a/arch/powerpc/platforms/powernv/opal-secvar.c
+++ b/arch/powerpc/platforms/powernv/opal-secvar.c
@@ -98,10 +98,35 @@ static int opal_set_variable(const char *key, u64 ksize, u8 *data, u64 dsize)
return opal_status_to_err(rc);
}

+static ssize_t opal_secvar_format(char *buf)
+{
+ ssize_t rc = 0;
+ struct device_node *node;
+ const char *format;
+
+ node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
+ if (!of_device_is_available(node)) {
+ rc = -ENODEV;
+ goto out;
+ }
+
+ rc = of_property_read_string(node, "format", &format);
+ if (rc)
+ goto out;
+
+ rc = snprintf(buf, SECVAR_MAX_FORMAT_LEN, "%s", format);
+
+out:
+ of_node_put(node);
+
+ return rc;
+}
+
static const struct secvar_operations opal_secvar_ops = {
.get = opal_get_variable,
.get_next = opal_get_next_variable,
.set = opal_set_variable,
+ .format = opal_secvar_format,
};

static int opal_secvar_probe(struct platform_device *pdev)
--
2.39.0