lib/verify.c

#include <linux/kernel.h>
#include <linux/verify.h>
#include <linux/module.h>

#include <linux/fs.h>

int verify_super_block(const struct super_block *sb)
{
	int ret;

	ret = kernel_rodata_address((unsigned long)sb->s_op);
	WARN_ONCE(!ret, "superblock: struct super_operations %pS is not const!", sb->s_op);

	return ret;
}

int verify_file_operations(const struct file_operations *fops)
{
	int ret = 0;

	if (IS_ERR_OR_NULL(fops))
		return 0;

	if (!kernel_rodata_address((unsigned long)fops)) {
		WARN_ONCE(1, "struct file_operations %pS (%p) is not const!", fops, fops);
		ret = -EINVAL;
	}

	/* check if owner is set correctly */
	if (fops->owner != __module_address((unsigned long)fops)) {
		WARN_ONCE(1, "struct file_operations %pS has .owner not set correctly", fops);
		ret = -EINVAL;
	}

	return ret;
}

int verify_struct_file(struct file *filp)
{
	int ret = 0;

	if (IS_ERR_OR_NULL(filp))
		return 0;

	if (verify_file_operations(filp->f_op)) {
		WARN_ONCE(1, "struct file %pS does not have a const f_ops %pS\n", filp, filp->f_op);
		ret = -EINVAL;
	}	

	return ret;
}

int verify_address_space(struct address_space *as)
{
	int ret = 0;

	if (!kernel_rodata_address((unsigned long)as->a_ops)) {
		WARN_ONCE(1, "struct address space %pS has non-const a_ops %pS\n", as, as->a_ops);
		ret = -EINVAL;
	}
	return ret;
}