diff options
Diffstat (limited to 'lib/fortify_kunit.c')
| -rw-r--r-- | lib/fortify_kunit.c | 662 |
1 files changed, 660 insertions, 2 deletions
diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c index 7830a9e64e..fdba0eaf19 100644 --- a/lib/fortify_kunit.c +++ b/lib/fortify_kunit.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Runtime test cases for CONFIG_FORTIFY_SOURCE that aren't expected to - * Oops the kernel on success. (For those, see drivers/misc/lkdtm/fortify.c) + * Runtime test cases for CONFIG_FORTIFY_SOURCE. For testing memcpy(), + * see FORTIFY_MEM_* tests in LKDTM (drivers/misc/lkdtm/fortify.c). * * For corner cases with UBSAN, try testing with: * @@ -15,17 +15,55 @@ */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +/* Redefine fortify_panic() to track failures. */ +void fortify_add_kunit_error(int write); +#define fortify_panic(func, write, avail, size, retfail) do { \ + __fortify_report(FORTIFY_REASON(func, write), avail, size); \ + fortify_add_kunit_error(write); \ + return (retfail); \ +} while (0) + #include <kunit/device.h> #include <kunit/test.h> +#include <kunit/test-bug.h> #include <linux/device.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/vmalloc.h> +/* Handle being built without CONFIG_FORTIFY_SOURCE */ +#ifndef __compiletime_strlen +# define __compiletime_strlen __builtin_strlen +#endif + +static struct kunit_resource read_resource; +static struct kunit_resource write_resource; +static int fortify_read_overflows; +static int fortify_write_overflows; + static const char array_of_10[] = "this is 10"; static const char *ptr_of_11 = "this is 11!"; static char array_unknown[] = "compiler thinks I might change"; +void fortify_add_kunit_error(int write) +{ + struct kunit_resource *resource; + struct kunit *current_test; + + current_test = kunit_get_current_test(); + if (!current_test) + return; + + resource = kunit_find_named_resource(current_test, + write ? "fortify_write_overflows" + : "fortify_read_overflows"); + if (!resource) + return; + + (*(int *)resource->data)++; + kunit_put_resource(resource); +} + static void known_sizes_test(struct kunit *test) { KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8); @@ -308,6 +346,610 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc) } while (0) DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc) +/* + * We can't have an array at the end of a structure or else + * builds without -fstrict-flex-arrays=3 will report them as + * being an unknown length. Additionally, add bytes before + * and after the string to catch over/underflows if tests + * fail. + */ +struct fortify_padding { + unsigned long bytes_before; + char buf[32]; + unsigned long bytes_after; +}; +/* Force compiler into not being able to resolve size at compile-time. */ +static volatile int unconst; + +static void strlen_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + int i, end = sizeof(pad.buf) - 1; + + /* Fill 31 bytes with valid characters. */ + for (i = 0; i < sizeof(pad.buf) - 1; i++) + pad.buf[i] = i + '0'; + /* Trailing bytes are still %NUL. */ + KUNIT_EXPECT_EQ(test, pad.buf[end], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* String is terminated, so strlen() is valid. */ + KUNIT_EXPECT_EQ(test, strlen(pad.buf), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + + /* Make string unterminated, and recount. */ + pad.buf[end] = 'A'; + end = sizeof(pad.buf); + KUNIT_EXPECT_EQ(test, strlen(pad.buf), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); +} + +static void strnlen_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + int i, end = sizeof(pad.buf) - 1; + + /* Fill 31 bytes with valid characters. */ + for (i = 0; i < sizeof(pad.buf) - 1; i++) + pad.buf[i] = i + '0'; + /* Trailing bytes are still %NUL. */ + KUNIT_EXPECT_EQ(test, pad.buf[end], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* String is terminated, so strnlen() is valid. */ + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf)), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + /* A truncated strnlen() will be safe, too. */ + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf) / 2), + sizeof(pad.buf) / 2); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + + /* Make string unterminated, and recount. */ + pad.buf[end] = 'A'; + end = sizeof(pad.buf); + /* Reading beyond with strncpy() will fail. */ + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 1), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 2), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); + + /* Early-truncated is safe still, though. */ + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); + + end = sizeof(pad.buf) / 2; + KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); +} + +static void strcpy_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[sizeof(pad.buf) + 1] = { }; + int i; + + /* Fill 31 bytes with valid characters. */ + for (i = 0; i < sizeof(src) - 2; i++) + src[i] = i + '0'; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strcpy() 1 less than of max size. */ + KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src) + == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Only last byte should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + src[sizeof(src) - 2] = 'A'; + /* But now we trip the overflow checking. */ + KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src) + == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + /* Trailing %NUL -- thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + src[sizeof(src) - 1] = 'A'; + /* And for sure now, two bytes past. */ + KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src) + == pad.buf); + /* + * Which trips both the strlen() on the unterminated src, + * and the resulting copy attempt. + */ + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + /* Trailing %NUL -- thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void strncpy_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[] = "Copy me fully into a small buffer and I will overflow!"; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strncpy() 1 less than of max size. */ + KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, + sizeof(pad.buf) + unconst - 1) + == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Only last byte should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* Legitimate (though unterminated) max-size strncpy. */ + KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, + sizeof(pad.buf) + unconst) + == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* No trailing %NUL -- thanks strncpy API. */ + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* But we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Now verify that FORTIFY is working... */ + KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, + sizeof(pad.buf) + unconst + 1) + == pad.buf); + /* Should catch the overflow. */ + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* And further... */ + KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src, + sizeof(pad.buf) + unconst + 2) + == pad.buf); + /* Should catch the overflow. */ + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void strscpy_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[] = "Copy me fully into a small buffer and I will overflow!"; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strscpy() 1 less than of max size. */ + KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, + sizeof(pad.buf) + unconst - 1), + -E2BIG); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Keeping space for %NUL, last two bytes should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* Legitimate max-size strscpy. */ + KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, + sizeof(pad.buf) + unconst), + -E2BIG); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* A trailing %NUL will exist. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + + /* Now verify that FORTIFY is working... */ + KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, + sizeof(pad.buf) + unconst + 1), + -E2BIG); + /* Should catch the overflow. */ + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* And much further... */ + KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, + sizeof(src) * 2 + unconst), + -E2BIG); + /* Should catch the overflow. */ + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + /* And we will not have gone beyond. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void strcat_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[sizeof(pad.buf) / 2] = { }; + char one[] = "A"; + char two[] = "BC"; + int i; + + /* Fill 15 bytes with valid characters. */ + for (i = 0; i < sizeof(src) - 1; i++) + src[i] = i + 'A'; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strcat() using less than half max size. */ + KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Legitimate strcat() now 2 bytes shy of end. */ + KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last two bytes should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* Add one more character to the end. */ + KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last byte should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* And this one char will overflow. */ + KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* And adding two will overflow more. */ + KUNIT_ASSERT_TRUE(test, strcat(pad.buf, two) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void strncat_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[sizeof(pad.buf)] = { }; + int i, partial; + + /* Fill 31 bytes with valid characters. */ + partial = sizeof(src) / 2 - 1; + for (i = 0; i < partial; i++) + src[i] = i + 'A'; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strncat() using less than half max size. */ + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Legitimate strncat() now 2 bytes shy of end. */ + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last two bytes should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* Add one more character to the end. */ + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last byte should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* And this one char will overflow. */ + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* And adding two will overflow more. */ + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 2) == pad.buf); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Force an unterminated destination, and overflow. */ + pad.buf[sizeof(pad.buf) - 1] = 'A'; + KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf); + /* This will have tripped both strlen() and strcat(). */ + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + /* But we should not go beyond the end. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void strlcat_test(struct kunit *test) +{ + struct fortify_padding pad = { }; + char src[sizeof(pad.buf)] = { }; + int i, partial; + int len = sizeof(pad.buf) + unconst; + + /* Fill 15 bytes with valid characters. */ + partial = sizeof(src) / 2 - 1; + for (i = 0; i < partial; i++) + src[i] = i + 'A'; + + /* Destination is %NUL-filled to start with. */ + KUNIT_EXPECT_EQ(test, pad.bytes_before, 0); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Legitimate strlcat() using less than half max size. */ + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Legitimate strlcat() now 2 bytes shy of end. */ + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial * 2); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last two bytes should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* Add one more character to the end. */ + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "Q", len), partial * 2 + 1); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0); + /* Last byte should be %NUL */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + + /* And this one char will overflow. */ + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "V", len * 2), len); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* And adding two will overflow more. */ + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "QQ", len * 2), len + 1); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + /* Last byte should be %NUL thanks to FORTIFY. */ + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Force an unterminated destination, and overflow. */ + pad.buf[sizeof(pad.buf) - 1] = 'A'; + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "TT", len * 2), len + 2); + /* This will have tripped both strlen() and strlcat(). */ + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0'); + KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0'); + /* But we should not go beyond the end. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); + + /* Force an unterminated source, and overflow. */ + memset(src, 'B', sizeof(src)); + pad.buf[sizeof(pad.buf) - 1] = '\0'; + KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len * 3), len - 1 + sizeof(src)); + /* This will have tripped both strlen() and strlcat(). */ + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3); + KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3); + KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0'); + /* But we should not go beyond the end. */ + KUNIT_EXPECT_EQ(test, pad.bytes_after, 0); +} + +static void memscan_test(struct kunit *test) +{ + char haystack[] = "Where oh where is my memory range?"; + char *mem = haystack + strlen("Where oh where is "); + char needle = 'm'; + size_t len = sizeof(haystack) + unconst; + + KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len), + mem); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + /* Catch too-large range. */ + KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len + 1), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len * 2), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); +} + +static void memchr_test(struct kunit *test) +{ + char haystack[] = "Where oh where is my memory range?"; + char *mem = haystack + strlen("Where oh where is "); + char needle = 'm'; + size_t len = sizeof(haystack) + unconst; + + KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len), + mem); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + /* Catch too-large range. */ + KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len + 1), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len * 2), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); +} + +static void memchr_inv_test(struct kunit *test) +{ + char haystack[] = "Where oh where is my memory range?"; + char *mem = haystack + 1; + char needle = 'W'; + size_t len = sizeof(haystack) + unconst; + + /* Normal search is okay. */ + KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len), + mem); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + /* Catch too-large range. */ + KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len + 1), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len * 2), + NULL); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); +} + +static void memcmp_test(struct kunit *test) +{ + char one[] = "My mind is going ..."; + char two[] = "My mind is going ... I can feel it."; + size_t one_len = sizeof(one) + unconst - 1; + size_t two_len = sizeof(two) + unconst - 1; + + /* We match the first string (ignoring the %NUL). */ + KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len), 0); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + /* Still in bounds, but no longer matching. */ + KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 1), -32); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + + /* Catch too-large ranges. */ + KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 2), INT_MIN); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + + KUNIT_ASSERT_EQ(test, memcmp(two, one, two_len + 2), INT_MIN); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); +} + +static void kmemdup_test(struct kunit *test) +{ + char src[] = "I got Doom running on it!"; + char *copy; + size_t len = sizeof(src) + unconst; + + /* Copy is within bounds. */ + copy = kmemdup(src, len, GFP_KERNEL); + KUNIT_EXPECT_NOT_NULL(test, copy); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + kfree(copy); + + /* Without %NUL. */ + copy = kmemdup(src, len - 1, GFP_KERNEL); + KUNIT_EXPECT_NOT_NULL(test, copy); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + kfree(copy); + + /* Tiny bounds. */ + copy = kmemdup(src, 1, GFP_KERNEL); + KUNIT_EXPECT_NOT_NULL(test, copy); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0); + kfree(copy); + + /* Out of bounds by 1 byte. */ + copy = kmemdup(src, len + 1, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1); + kfree(copy); + + /* Way out of bounds. */ + copy = kmemdup(src, len * 2, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2); + kfree(copy); + + /* Starting offset causing out of bounds. */ + copy = kmemdup(src + 1, len, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR); + KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3); + kfree(copy); +} + +static int fortify_test_init(struct kunit *test) +{ + if (!IS_ENABLED(CONFIG_FORTIFY_SOURCE)) + kunit_skip(test, "Not built with CONFIG_FORTIFY_SOURCE=y"); + + fortify_read_overflows = 0; + kunit_add_named_resource(test, NULL, NULL, &read_resource, + "fortify_read_overflows", + &fortify_read_overflows); + fortify_write_overflows = 0; + kunit_add_named_resource(test, NULL, NULL, &write_resource, + "fortify_write_overflows", + &fortify_write_overflows); + return 0; +} + static struct kunit_case fortify_test_cases[] = { KUNIT_CASE(known_sizes_test), KUNIT_CASE(control_flow_split_test), @@ -319,11 +961,27 @@ static struct kunit_case fortify_test_cases[] = { KUNIT_CASE(alloc_size_kvmalloc_dynamic_test), KUNIT_CASE(alloc_size_devm_kmalloc_const_test), KUNIT_CASE(alloc_size_devm_kmalloc_dynamic_test), + KUNIT_CASE(strlen_test), + KUNIT_CASE(strnlen_test), + KUNIT_CASE(strcpy_test), + KUNIT_CASE(strncpy_test), + KUNIT_CASE(strscpy_test), + KUNIT_CASE(strcat_test), + KUNIT_CASE(strncat_test), + KUNIT_CASE(strlcat_test), + /* skip memset: performs bounds checking on whole structs */ + /* skip memcpy: still using warn-and-overwrite instead of hard-fail */ + KUNIT_CASE(memscan_test), + KUNIT_CASE(memchr_test), + KUNIT_CASE(memchr_inv_test), + KUNIT_CASE(memcmp_test), + KUNIT_CASE(kmemdup_test), {} }; static struct kunit_suite fortify_test_suite = { .name = "fortify", + .init = fortify_test_init, .test_cases = fortify_test_cases, }; |