/*
 * Security plug functions
 *
 * Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
 * Copyright (C) 2001-2002 Greg Kroah-Hartman <greg@kroah.com>
 * Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/security.h>

#define SECURITY_SCAFFOLD_VERSION       "1.0.0"

/* things that live in dummy.c */
extern struct security_operations dummy_security_ops;
extern void security_fixup_ops (struct security_operations *ops);

struct security_operations *security_ops;       /* Initialized to NULL */

static inline int verify (struct security_operations *ops)
{
        /* verify the security_operations structure exists */
        if (!ops) {
                printk (KERN_INFO "Passed a NULL security_operations "
                        "pointer, %s failed.\n", __FUNCTION__);
                return -EINVAL;
        }
        security_fixup_ops (ops);
        return 0;
}

static void __init do_security_initcalls(void)
{
        initcall_t *call;
        call = &__security_initcall_start;
        while (call < &__security_initcall_end) {
                (*call)();
                call++;
        }
}

/**
 * security_scaffolding_startup - initialzes the security scaffolding framework
 *
 * This should be called early in the kernel initialization sequence.
 */
int __init security_scaffolding_startup (void)
{
        printk (KERN_INFO "Security Scaffold v" SECURITY_SCAFFOLD_VERSION
                " initialized\n");

        if (verify (&dummy_security_ops)) {
                printk (KERN_ERR "%s could not verify "
                        "dummy_security_ops structure.\n", __FUNCTION__);
                return -EIO;
        }

        security_ops = &dummy_security_ops;
        do_security_initcalls();

        return 0;
}

/**
 * register_security - registers a security framework with the kernel
 * @ops: a pointer to the struct security_options that is to be registered
 *
 * This function is to allow a security module to register itself with the
 * kernel security subsystem.  Some rudimentary checking is done on the @ops
 * value passed to this function.  A call to unregister_security() should be
 * done to remove this security_options structure from the kernel.
 *
 * If there is already a security module registered with the kernel,
 * an error will be returned.  Otherwise 0 is returned on success.
 */
int register_security (struct security_operations *ops)
{
        if (verify (ops)) {
                printk (KERN_INFO "%s could not verify "
                        "security_operations structure.\n", __FUNCTION__);
                return -EINVAL;
        }

        if (security_ops != &dummy_security_ops) {
                printk (KERN_INFO "There is already a security "
                        "framework initialized, %s failed.\n", __FUNCTION__);
                return -EINVAL;
        }

        security_ops = ops;

        return 0;
}

/**
 * unregister_security - unregisters a security framework with the kernel
 * @ops: a pointer to the struct security_options that is to be registered
 *
 * This function removes a struct security_operations variable that had
 * previously been registered with a successful call to register_security().
 *
 * If @ops does not match the valued previously passed to register_security()
 * an error is returned.  Otherwise the default security options is set to the
 * the dummy_security_ops structure, and 0 is returned.
 */
int unregister_security (struct security_operations *ops)
{
        if (ops != security_ops) {
                printk (KERN_INFO "%s: trying to unregister "
                        "a security_opts structure that is not "
                        "registered, failing.\n", __FUNCTION__);
                return -EINVAL;
        }

        security_ops = &dummy_security_ops;

        return 0;
}

/**
 * mod_reg_security - allows security modules to be "stacked"
 * @name: a pointer to a string with the name of the security_options to be registered
 * @ops: a pointer to the struct security_options that is to be registered
 *
 * This function allows security modules to be stacked if the currently loaded
 * security module allows this to happen.  It passes the @name and @ops to the
 * register_security function of the currently loaded security module.
 *
 * The return value depends on the currently loaded security module, with 0 as
 * success.
 */
int mod_reg_security (const char *name, struct security_operations *ops)
{
        if (verify (ops)) {
                printk (KERN_INFO "%s could not verify "
                        "security operations.\n", __FUNCTION__);
                return -EINVAL;
        }

        if (ops == security_ops) {
                printk (KERN_INFO "%s security operations "
                        "already registered.\n", __FUNCTION__);
                return -EINVAL;
        }

        return security_ops->register_security (name, ops);
}

/**
 * mod_unreg_security - allows a security module registered with mod_reg_security() to be unloaded
 * @name: a pointer to a string with the name of the security_options to be removed
 * @ops: a pointer to the struct security_options that is to be removed
 *
 * This function allows security modules that have been successfully registered
 * with a call to mod_reg_security() to be unloaded from the system.
 * This calls the currently loaded security module's unregister_security() call
 * with the @name and @ops variables.
 *
 * The return value depends on the currently loaded security module, with 0 as
 * success.
 */
int mod_unreg_security (const char *name, struct security_operations *ops)
{
        if (ops == security_ops) {
                printk (KERN_INFO "%s invalid attempt to unregister "
                        " primary security ops.\n", __FUNCTION__);
                return -EINVAL;
        }

        return security_ops->unregister_security (name, ops);
}

/**
 * capable - calls the currently loaded security module's capable() function with the specified capability
 * @cap: the requested capability level.
 *
 * This function calls the currently loaded security module's cabable()
 * function with a pointer to the current task and the specified @cap value.
 *
 * This allows the security module to implement the capable function call
 * however it chooses to.
 */
int capable (int cap)
{
        if (security_ops->capable (current, cap)) {
                /* capability denied */
                return 0;
        }

        /* capability granted */
        current->flags |= PF_SUPERPRIV;
        return 1;
}

EXPORT_SYMBOL_GPL(register_security);
EXPORT_SYMBOL_GPL(unregister_security);
EXPORT_SYMBOL_GPL(mod_reg_security);
EXPORT_SYMBOL_GPL(mod_unreg_security);
EXPORT_SYMBOL(capable);
EXPORT_SYMBOL(security_ops);