[PATCH v6 11/26] powerpc/secvar: Allow backend to populate static list of variable names

Andrew Donnellan
2023-02-10T08:05:10Z

Currently, the list of variables is populated by calling
secvar_ops->get_next() repeatedly, which is explicitly modelled on the
OPAL API (including the keylen parameter).

For the upcoming PLPKS backend, we have a static list of variable names.
It is messy to fit that into get_next(), so instead, let the backend put
a NULL-terminated array of variable names into secvar_ops->var_names,
which will be used if get_next() is undefined.

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

---

v3: New patch (ajd/mpe)

v6: Add newlines for better aesthetics (stefanb)
---
arch/powerpc/include/asm/secvar.h | 4 ++
arch/powerpc/kernel/secvar-sysfs.c | 69 +++++++++++++++++++++---------
2 files changed, 52 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index 011a53a8076c..4828e0ab7e3c 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h
@@ -21,6 +21,10 @@ struct secvar_operations {
ssize_t (*format)(char *buf, size_t bufsize);
int (*max_size)(u64 *max_size);
const struct attribute **config_attrs;
+
+ // NULL-terminated array of fixed variable names
+ // Only used if get_next() isn't provided
+ const char * const *var_names;
};

#ifdef CONFIG_PPC_SECURE_BOOT
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index 7df32be86507..bfb19f22c6ba 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -157,9 +157,31 @@ static int secvar_sysfs_config(struct kobject *kobj)
return 0;
}

-static int secvar_sysfs_load(void)
+static int add_var(const char *name)
{
struct kobject *kobj;
+ int rc;
+
+ kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
+ if (!kobj)
+ return -ENOMEM;
+
+ kobject_init(kobj, &secvar_ktype);
+
+ rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
+ if (rc) {
+ pr_warn("kobject_add error %d for attribute: %s\n", rc,
+ name);
+ kobject_put(kobj);
+ return rc;
+ }
+
+ kobject_uevent(kobj, KOBJ_ADD);
+ return 0;
+}
+
+static int secvar_sysfs_load(void)
+{
u64 namesize = 0;
char *name;
int rc;
@@ -179,31 +201,28 @@ static int secvar_sysfs_load(void)
break;
}

- kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
- if (!kobj) {
- rc = -ENOMEM;
- break;
- }
-
- kobject_init(kobj, &secvar_ktype);
-
- rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
- if (rc) {
- pr_warn("kobject_add error %d for attribute: %s\n", rc,
- name);
- kobject_put(kobj);
- kobj = NULL;
- }
-
- if (kobj)
- kobject_uevent(kobj, KOBJ_ADD);
-
+ rc = add_var(name);
} while (!rc);

kfree(name);
return rc;
}

+static int secvar_sysfs_load_static(void)
+{
+ const char * const *name_ptr = secvar_ops->var_names;
+ int rc;
+
+ while (*name_ptr) {
+ rc = add_var(*name_ptr);
+ if (rc)
+ return rc;
+ name_ptr++;
+ }
+
+ return 0;
+}
+
static int secvar_sysfs_init(void)
{
int rc;
@@ -245,7 +264,15 @@ static int secvar_sysfs_init(void)
goto err;
}

- secvar_sysfs_load();
+ if (secvar_ops->get_next)
+ rc = secvar_sysfs_load();
+ else
+ rc = secvar_sysfs_load_static();
+
+ if (rc) {
+ pr_err("Failed to create variable attributes\n");
+ goto err;
+ }

return 0;
err:
--
2.39.1