Due to sysfs constraints, when writing to a variable, we can only handle
writes of up to PAGE_SIZE.
It's possible that the maximum object size is larger than PAGE_SIZE, in
which case, print a warning on boot so that the user is aware.
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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-13-ajd@linux.ibm.com
static int secvar_sysfs_init(void)
{
+ u64 max_size;
int rc;
if (!secvar_ops) {
goto err;
}
+ // Due to sysfs limitations, we will only ever get a write buffer of
+ // up to 1 page in size. Print a warning if this is potentially going
+ // to cause problems, so that the user is aware.
+ secvar_ops->max_size(&max_size);
+ if (max_size > PAGE_SIZE)
+ pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n",
+ PAGE_SIZE, max_size);
+
return 0;
err:
kobject_put(secvar_kobj);