From a9bc15cb1cbd62b498b55958e92a90d0ea52a4b8 Mon Sep 17 00:00:00 2001 From: Rick Edgecombe Date: Mon, 25 Mar 2024 19:16:56 -0700 Subject: selftests/x86: add placement guard gap test for shstk The existing shadow stack test for guard gaps just checks that new mappings are not placed in an existing mapping's guard gap. Add one that checks that new mappings are not placed such that preexisting mappings are in the new mappings guard gap. Link: https://lkml.kernel.org/r/20240326021656.202649-15-rick.p.edgecombe@intel.com Signed-off-by: Rick Edgecombe Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Aneesh Kumar K.V Cc: Borislav Petkov (AMD) Cc: Christophe Leroy Cc: Dan Williams Cc: Dave Hansen Cc: Deepak Gupta Cc: Guo Ren Cc: Helge Deller Cc: H. Peter Anvin (Intel) Cc: Ingo Molnar Cc: "James E.J. Bottomley" Cc: Kees Cook Cc: Kirill A. Shutemov Cc: Liam R. Howlett Cc: Mark Brown Cc: Michael Ellerman Cc: Naveen N. Rao Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- tools/testing/selftests/x86/test_shadow_stack.c | 67 +++++++++++++++++++++++-- 1 file changed, 63 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/x86/test_shadow_stack.c b/tools/testing/selftests/x86/test_shadow_stack.c index 757e6527f67e..ee909a7927f9 100644 --- a/tools/testing/selftests/x86/test_shadow_stack.c +++ b/tools/testing/selftests/x86/test_shadow_stack.c @@ -556,7 +556,7 @@ struct node { * looked at the shadow stack gaps. * 5. See if it landed in the gap. */ -int test_guard_gap(void) +int test_guard_gap_other_gaps(void) { void *free_area, *shstk, *test_map = (void *)0xFFFFFFFFFFFFFFFF; struct node *head = NULL, *cur; @@ -593,11 +593,64 @@ int test_guard_gap(void) if (shstk - test_map - PAGE_SIZE != PAGE_SIZE) return 1; - printf("[OK]\tGuard gap test\n"); + printf("[OK]\tGuard gap test, other mapping's gaps\n"); return 0; } +/* Tests respecting the guard gap of the mapping getting placed */ +int test_guard_gap_new_mappings_gaps(void) +{ + void *free_area, *shstk_start, *test_map = (void *)0xFFFFFFFFFFFFFFFF; + struct node *head = NULL, *cur; + int ret = 0; + + free_area = mmap(0, PAGE_SIZE * 4, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + munmap(free_area, PAGE_SIZE * 4); + + /* Test letting map_shadow_stack find a free space */ + shstk_start = mmap(free_area, PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (shstk_start == MAP_FAILED || shstk_start != free_area) + return 1; + + while (test_map > shstk_start) { + test_map = (void *)syscall(__NR_map_shadow_stack, 0, PAGE_SIZE, 0); + if (test_map == MAP_FAILED) { + printf("[INFO]\tmap_shadow_stack MAP_FAILED\n"); + ret = 1; + break; + } + + cur = malloc(sizeof(*cur)); + cur->mapping = test_map; + + cur->next = head; + head = cur; + + if (test_map == free_area + PAGE_SIZE) { + printf("[INFO]\tNew mapping has other mapping in guard gap!\n"); + ret = 1; + break; + } + } + + while (head) { + cur = head; + head = cur->next; + munmap(cur->mapping, PAGE_SIZE); + free(cur); + } + + munmap(shstk_start, PAGE_SIZE); + + if (!ret) + printf("[OK]\tGuard gap test, placement mapping's gaps\n"); + + return ret; +} + /* * Too complicated to pull it out of the 32 bit header, but also get the * 64 bit one needed above. Just define a copy here. @@ -850,9 +903,15 @@ int main(int argc, char *argv[]) goto out; } - if (test_guard_gap()) { + if (test_guard_gap_other_gaps()) { + ret = 1; + printf("[FAIL]\tGuard gap test, other mappings' gaps\n"); + goto out; + } + + if (test_guard_gap_new_mappings_gaps()) { ret = 1; - printf("[FAIL]\tGuard gap test\n"); + printf("[FAIL]\tGuard gap test, placement mapping's gaps\n"); goto out; } -- cgit v1.2.3