diff options
Diffstat (limited to 'drivers/misc/lkdtm/usercopy.c')
| -rw-r--r-- | drivers/misc/lkdtm/usercopy.c | 113 |
1 files changed, 98 insertions, 15 deletions
diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index 7852b9fc7c479..6215ec995cd3c 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c @@ -5,6 +5,7 @@ */ #include "lkdtm.h" #include <linux/slab.h> +#include <linux/highmem.h> #include <linux/vmalloc.h> #include <linux/sched/task_stack.h> #include <linux/mman.h> @@ -130,7 +131,7 @@ free_user: * This checks for whole-object size validation with hardened usercopy, * with or without usercopy whitelisting. */ -static void do_usercopy_heap_size(bool to_user) +static void do_usercopy_slab_size(bool to_user) { unsigned long user_addr; unsigned char *one, *two; @@ -196,9 +197,9 @@ free_kernel: /* * This checks for the specific whitelist window within an object. If this - * test passes, then do_usercopy_heap_size() tests will pass too. + * test passes, then do_usercopy_slab_size() tests will pass too. */ -static void do_usercopy_heap_whitelist(bool to_user) +static void do_usercopy_slab_whitelist(bool to_user) { unsigned long user_alloc; unsigned char *buf = NULL; @@ -272,24 +273,24 @@ free_alloc: } /* Callable tests. */ -static void lkdtm_USERCOPY_HEAP_SIZE_TO(void) +static void lkdtm_USERCOPY_SLAB_SIZE_TO(void) { - do_usercopy_heap_size(true); + do_usercopy_slab_size(true); } -static void lkdtm_USERCOPY_HEAP_SIZE_FROM(void) +static void lkdtm_USERCOPY_SLAB_SIZE_FROM(void) { - do_usercopy_heap_size(false); + do_usercopy_slab_size(false); } -static void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void) +static void lkdtm_USERCOPY_SLAB_WHITELIST_TO(void) { - do_usercopy_heap_whitelist(true); + do_usercopy_slab_whitelist(true); } -static void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void) +static void lkdtm_USERCOPY_SLAB_WHITELIST_FROM(void) { - do_usercopy_heap_whitelist(false); + do_usercopy_slab_whitelist(false); } static void lkdtm_USERCOPY_STACK_FRAME_TO(void) @@ -341,6 +342,86 @@ free_user: vm_munmap(user_addr, PAGE_SIZE); } +/* + * This expects "kaddr" to point to a PAGE_SIZE allocation, which means + * a more complete test that would include copy_from_user() would risk + * memory corruption. Just test copy_to_user() here, as that exercises + * almost exactly the same code paths. + */ +static void do_usercopy_page_span(const char *name, void *kaddr) +{ + unsigned long uaddr; + + uaddr = vm_mmap(NULL, 0, PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (uaddr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + /* Initialize contents. */ + memset(kaddr, 0xAA, PAGE_SIZE); + + /* Bump the kaddr forward to detect a page-spanning overflow. */ + kaddr += PAGE_SIZE / 2; + + pr_info("attempting good copy_to_user() from kernel %s: %px\n", + name, kaddr); + if (copy_to_user((void __user *)uaddr, kaddr, + unconst + (PAGE_SIZE / 2))) { + pr_err("copy_to_user() failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user() from kernel %s: %px\n", + name, kaddr); + if (copy_to_user((void __user *)uaddr, kaddr, unconst + PAGE_SIZE)) { + pr_warn("Good, copy_to_user() failed, but lacked Oops(?!)\n"); + goto free_user; + } + + pr_err("FAIL: bad copy_to_user() not detected!\n"); + pr_expected_config_param(CONFIG_HARDENED_USERCOPY, "hardened_usercopy"); + +free_user: + vm_munmap(uaddr, PAGE_SIZE); +} + +static void lkdtm_USERCOPY_VMALLOC(void) +{ + void *addr; + + addr = vmalloc(PAGE_SIZE); + if (!addr) { + pr_err("vmalloc() failed!?\n"); + return; + } + do_usercopy_page_span("vmalloc", addr); + vfree(addr); +} + +static void lkdtm_USERCOPY_FOLIO(void) +{ + struct folio *folio; + void *addr; + + /* + * FIXME: Folio checking currently misses 0-order allocations, so + * allocate and bump forward to the last page. + */ + folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, 1); + if (!folio) { + pr_err("folio_alloc() failed!?\n"); + return; + } + addr = folio_address(folio); + if (addr) + do_usercopy_page_span("folio", addr + PAGE_SIZE); + else + pr_err("folio_address() failed?!\n"); + folio_put(folio); +} + void __init lkdtm_usercopy_init(void) { /* Prepare cache that lacks SLAB_USERCOPY flag. */ @@ -358,13 +439,15 @@ void __exit lkdtm_usercopy_exit(void) } static struct crashtype crashtypes[] = { - CRASHTYPE(USERCOPY_HEAP_SIZE_TO), - CRASHTYPE(USERCOPY_HEAP_SIZE_FROM), - CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO), - CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM), + CRASHTYPE(USERCOPY_SLAB_SIZE_TO), + CRASHTYPE(USERCOPY_SLAB_SIZE_FROM), + CRASHTYPE(USERCOPY_SLAB_WHITELIST_TO), + CRASHTYPE(USERCOPY_SLAB_WHITELIST_FROM), CRASHTYPE(USERCOPY_STACK_FRAME_TO), CRASHTYPE(USERCOPY_STACK_FRAME_FROM), CRASHTYPE(USERCOPY_STACK_BEYOND), + CRASHTYPE(USERCOPY_VMALLOC), + CRASHTYPE(USERCOPY_FOLIO), CRASHTYPE(USERCOPY_KERNEL), }; |