9ccaf77cf0
This removes the CONFIG_DEBUG_RODATA option and makes it always enabled. This simplifies the code and also makes it clearer that read-only mapped memory is just as fundamental a security feature in kernel-space as it is in user-space. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Brown <david.brown@linaro.org> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Emese Revfy <re.emese@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathias Krause <minipli@googlemail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: PaX Team <pageexec@freemail.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-hardening@lists.openwall.com Cc: linux-arch <linux-arch@vger.kernel.org> Link: http://lkml.kernel.org/r/1455748879-21872-4-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/*
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* test_rodata.c: functional test for mark_rodata_ro function
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*
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* (C) Copyright 2008 Intel Corporation
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* Author: Arjan van de Ven <arjan@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#include <linux/module.h>
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#include <asm/cacheflush.h>
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#include <asm/sections.h>
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#include <asm/asm.h>
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int rodata_test(void)
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{
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unsigned long result;
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unsigned long start, end;
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/* test 1: read the value */
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/* If this test fails, some previous testrun has clobbered the state */
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if (!rodata_test_data) {
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printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
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return -ENODEV;
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}
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/* test 2: write to the variable; this should fault */
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/*
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* If this test fails, we managed to overwrite the data
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*
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* This is written in assembly to be able to catch the
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* exception that is supposed to happen in the correct
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* case
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*/
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result = 1;
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asm volatile(
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"0: mov %[zero],(%[rodata_test])\n"
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" mov %[zero], %[rslt]\n"
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"1:\n"
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".section .fixup,\"ax\"\n"
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"2: jmp 1b\n"
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".previous\n"
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_ASM_EXTABLE(0b,2b)
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: [rslt] "=r" (result)
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: [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
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);
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if (!result) {
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printk(KERN_ERR "rodata_test: test data was not read only\n");
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return -ENODEV;
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}
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/* test 3: check the value hasn't changed */
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/* If this test fails, we managed to overwrite the data */
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if (!rodata_test_data) {
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printk(KERN_ERR "rodata_test: Test 3 fails (end data)\n");
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return -ENODEV;
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}
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/* test 4: check if the rodata section is 4Kb aligned */
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start = (unsigned long)__start_rodata;
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end = (unsigned long)__end_rodata;
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if (start & (PAGE_SIZE - 1)) {
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printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
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return -ENODEV;
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}
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if (end & (PAGE_SIZE - 1)) {
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printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
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return -ENODEV;
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}
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return 0;
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}
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Testcase for marking rodata as read-only");
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MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
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