83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2020 Francis Laniel <laniel_francis@privacyrequired.com>
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*
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* Add tests related to fortified functions in this file.
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*/
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#include "lkdtm.h"
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#include <linux/string.h>
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#include <linux/slab.h>
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/*
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* Calls fortified strscpy to test that it returns the same result as vanilla
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* strscpy and generate a panic because there is a write overflow (i.e. src
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* length is greater than dst length).
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*/
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void lkdtm_FORTIFIED_STRSCPY(void)
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{
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char *src;
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char dst[5];
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struct {
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union {
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char big[10];
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char src[5];
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};
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} weird = { .big = "hello!" };
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char weird_dst[sizeof(weird.src) + 1];
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src = kstrdup("foobar", GFP_KERNEL);
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if (src == NULL)
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return;
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/* Vanilla strscpy returns -E2BIG if size is 0. */
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if (strscpy(dst, src, 0) != -E2BIG)
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pr_warn("FAIL: strscpy() of 0 length did not return -E2BIG\n");
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/* Vanilla strscpy returns -E2BIG if src is truncated. */
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if (strscpy(dst, src, sizeof(dst)) != -E2BIG)
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pr_warn("FAIL: strscpy() did not return -E2BIG while src is truncated\n");
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/* After above call, dst must contain "foob" because src was truncated. */
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if (strncmp(dst, "foob", sizeof(dst)) != 0)
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pr_warn("FAIL: after strscpy() dst does not contain \"foob\" but \"%s\"\n",
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dst);
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/* Shrink src so the strscpy() below succeeds. */
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src[3] = '\0';
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/*
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* Vanilla strscpy returns number of character copied if everything goes
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* well.
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*/
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if (strscpy(dst, src, sizeof(dst)) != 3)
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pr_warn("FAIL: strscpy() did not return 3 while src was copied entirely truncated\n");
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/* After above call, dst must contain "foo" because src was copied. */
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if (strncmp(dst, "foo", sizeof(dst)) != 0)
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pr_warn("FAIL: after strscpy() dst does not contain \"foo\" but \"%s\"\n",
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dst);
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/* Test when src is embedded inside a union. */
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strscpy(weird_dst, weird.src, sizeof(weird_dst));
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if (strcmp(weird_dst, "hello") != 0)
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pr_warn("FAIL: after strscpy() weird_dst does not contain \"hello\" but \"%s\"\n",
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weird_dst);
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/* Restore src to its initial value. */
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src[3] = 'b';
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/*
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* Use strlen here so size cannot be known at compile time and there is
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* a runtime write overflow.
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*/
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strscpy(dst, src, strlen(src));
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pr_warn("FAIL: No overflow in above strscpy()\n");
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kfree(src);
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}
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