Messages in this thread Patch in this message | | | From | Igor Stoppa <> | Subject | [PATCH 4/6] rodata_test: add verification for __wr_after_init | Date | Tue, 4 Dec 2018 14:18:03 +0200 |
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The write protection of the __wr_after_init data can be verified with the same methodology used for const data.
Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com>
CC: Andy Lutomirski <luto@amacapital.net> CC: Nadav Amit <nadav.amit@gmail.com> CC: Matthew Wilcox <willy@infradead.org> CC: Peter Zijlstra <peterz@infradead.org> CC: Kees Cook <keescook@chromium.org> CC: Dave Hansen <dave.hansen@linux.intel.com> CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- mm/rodata_test.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/mm/rodata_test.c b/mm/rodata_test.c index 3c1e515ca9b1..a98d088ad9cc 100644 --- a/mm/rodata_test.c +++ b/mm/rodata_test.c @@ -16,7 +16,19 @@ #define INIT_TEST_VAL 0xC3 +/* + * Note: __ro_after_init data is, for every practical effect, equivalent to + * const data, since they are even write protected at the same time; there + * is no need for separate testing. + * __wr_after_init data, otoh, is altered also after the write protection + * takes place and it cannot be exploitable for altering more permanent + * data. + */ + static const int rodata_test_data = INIT_TEST_VAL; +static int wr_after_init_test_data __wr_after_init = INIT_TEST_VAL; +extern long __start_wr_after_init; +extern long __end_wr_after_init; static bool test_data(char *data_type, const int *data, unsigned long start, unsigned long end) @@ -60,6 +72,9 @@ void rodata_test(void) { if (test_data("rodata", &rodata_test_data, (unsigned long)&__start_rodata, - (unsigned long)&__end_rodata)) + (unsigned long)&__end_rodata) && + test_data("wr after init data", &wr_after_init_test_data, + (unsigned long)&__start_wr_after_init, + (unsigned long)&__end_wr_after_init)) pr_info("all tests were successful\n"); } -- 2.19.1
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