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When the kernel is running in secure boot mode, we lock down the kernel to prevent userspace from modifying the running kernel image. Whilst this includes prohibiting access to things like /dev/mem, it must also prevent access by means of configuring driver modules in such a way as to cause a device to access or modify the kernel image. To this end, annotate module_param* statements that refer to hardware configuration and indicate for future reference what type of parameter they specify. The parameter parser in the core sees this information and can skip such parameters with an error message if the kernel is locked down. The module initialisation then runs as normal, but just sees whatever the default values for those parameters is. Note that we do still need to do the module initialisation because some drivers have viable defaults set in case parameters aren't specified and some drivers support automatic configuration (e.g. PNP or PCI) in addition to manually coded parameters. This patch annotates drivers in drivers/misc/. Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> cc: Arnd Bergmann <arnd@arndb.de>
65 lines
1.5 KiB
C
65 lines
1.5 KiB
C
/*
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* Dummy IRQ handler driver.
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*
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* This module only registers itself as a handler that is specified to it
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* by the 'irq' parameter.
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*
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* The sole purpose of this module is to help with debugging of systems on
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* which spurious IRQs would happen on disabled IRQ vector.
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*
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* Copyright (C) 2013 Jiri Kosina
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*/
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/*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/irq.h>
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#include <linux/interrupt.h>
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static int irq = -1;
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static irqreturn_t dummy_interrupt(int irq, void *dev_id)
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{
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static int count = 0;
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if (count == 0) {
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printk(KERN_INFO "dummy-irq: interrupt occurred on IRQ %d\n",
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irq);
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count++;
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}
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return IRQ_NONE;
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}
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static int __init dummy_irq_init(void)
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{
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if (irq < 0) {
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printk(KERN_ERR "dummy-irq: no IRQ given. Use irq=N\n");
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return -EIO;
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}
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if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) {
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printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq);
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return -EIO;
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}
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printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq);
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return 0;
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}
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static void __exit dummy_irq_exit(void)
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{
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printk(KERN_INFO "dummy-irq unloaded\n");
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free_irq(irq, &irq);
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}
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module_init(dummy_irq_init);
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module_exit(dummy_irq_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Jiri Kosina");
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module_param_hw(irq, uint, irq, 0444);
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MODULE_PARM_DESC(irq, "The IRQ to register for");
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MODULE_DESCRIPTION("Dummy IRQ handler driver");
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