diff options
Diffstat (limited to 'drivers/misc')
| -rw-r--r-- | drivers/misc/Makefile | 1 | ||||
| -rw-r--r-- | drivers/misc/lkdtm.h | 13 | ||||
| -rw-r--r-- | drivers/misc/lkdtm_core.c | 279 | ||||
| -rw-r--r-- | drivers/misc/lkdtm_usercopy.c | 315 |
4 files changed, 342 insertions, 266 deletions
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 7d45ed4a1549..e6b2778731ff 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -60,6 +60,7 @@ obj-$(CONFIG_PANEL) += panel.o lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o +lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o OBJCOPYFLAGS := OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \ diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h index 9531fa3be4c3..ef290a2c8816 100644 --- a/drivers/misc/lkdtm.h +++ b/drivers/misc/lkdtm.h @@ -1,6 +1,19 @@ #ifndef __LKDTM_H #define __LKDTM_H +/* lkdtm_rodata.c */ void lkdtm_rodata_do_nothing(void); +/* lkdtm_usercopy.c */ +void __init lkdtm_usercopy_init(void); +void __exit lkdtm_usercopy_exit(void); +void lkdtm_USERCOPY_HEAP_SIZE_TO(void); +void lkdtm_USERCOPY_HEAP_SIZE_FROM(void); +void lkdtm_USERCOPY_HEAP_FLAG_TO(void); +void lkdtm_USERCOPY_HEAP_FLAG_FROM(void); +void lkdtm_USERCOPY_STACK_FRAME_TO(void); +void lkdtm_USERCOPY_STACK_FRAME_FROM(void); +void lkdtm_USERCOPY_STACK_BEYOND(void); +void lkdtm_USERCOPY_KERNEL(void); + #endif diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index 1454d58aa278..74376920ed55 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -193,10 +193,6 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; -static size_t cache_size = 1024; -static struct kmem_cache *bad_cache; - -static const unsigned char test_text[] = "This is a test.\n"; static const unsigned long rodata = 0xAA55AA55; static unsigned long ro_after_init __ro_after_init = 0x55AA5500; @@ -403,255 +399,6 @@ static void execute_user_location(void *dst) func(); } -/* - * Instead of adding -Wno-return-local-addr, just pass the stack address - * through a function to obfuscate it from the compiler. - */ -static noinline unsigned char *trick_compiler(unsigned char *stack) -{ - return stack + 0; -} - -static noinline unsigned char *do_usercopy_stack_callee(int value) -{ - unsigned char buf[32]; - int i; - - /* Exercise stack to avoid everything living in registers. */ - for (i = 0; i < sizeof(buf); i++) { - buf[i] = value & 0xff; - } - - return trick_compiler(buf); -} - -static noinline void do_usercopy_stack(bool to_user, bool bad_frame) -{ - unsigned long user_addr; - unsigned char good_stack[32]; - unsigned char *bad_stack; - int i; - - /* Exercise stack to avoid everything living in registers. */ - for (i = 0; i < sizeof(good_stack); i++) - good_stack[i] = test_text[i % sizeof(test_text)]; - - /* This is a pointer to outside our current stack frame. */ - if (bad_frame) { - bad_stack = do_usercopy_stack_callee((uintptr_t)bad_stack); - } else { - /* Put start address just inside stack. */ - bad_stack = task_stack_page(current) + THREAD_SIZE; - bad_stack -= sizeof(unsigned long); - } - - user_addr = vm_mmap(NULL, 0, PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (user_addr >= TASK_SIZE) { - pr_warn("Failed to allocate user memory\n"); - return; - } - - if (to_user) { - pr_info("attempting good copy_to_user of local stack\n"); - if (copy_to_user((void __user *)user_addr, good_stack, - sizeof(good_stack))) { - pr_warn("copy_to_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_to_user of distant stack\n"); - if (copy_to_user((void __user *)user_addr, bad_stack, - sizeof(good_stack))) { - pr_warn("copy_to_user failed, but lacked Oops\n"); - goto free_user; - } - } else { - /* - * There isn't a safe way to not be protected by usercopy - * if we're going to write to another thread's stack. - */ - if (!bad_frame) - goto free_user; - - pr_info("attempting good copy_from_user of local stack\n"); - if (copy_from_user(good_stack, (void __user *)user_addr, - sizeof(good_stack))) { - pr_warn("copy_from_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_from_user of distant stack\n"); - if (copy_from_user(bad_stack, (void __user *)user_addr, - sizeof(good_stack))) { - pr_warn("copy_from_user failed, but lacked Oops\n"); - goto free_user; - } - } - -free_user: - vm_munmap(user_addr, PAGE_SIZE); -} - -static void do_usercopy_kernel(void) -{ - unsigned long user_addr; - - user_addr = vm_mmap(NULL, 0, PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (user_addr >= TASK_SIZE) { - pr_warn("Failed to allocate user memory\n"); - return; - } - - pr_info("attempting good copy_to_user from kernel rodata\n"); - if (copy_to_user((void __user *)user_addr, test_text, - sizeof(test_text))) { - pr_warn("copy_to_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_to_user from kernel text\n"); - if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) { - pr_warn("copy_to_user failed, but lacked Oops\n"); - goto free_user; - } - -free_user: - vm_munmap(user_addr, PAGE_SIZE); -} - -static void do_usercopy_heap_size(bool to_user) -{ - unsigned long user_addr; - unsigned char *one, *two; - size_t size = 1024; - - one = kmalloc(size, GFP_KERNEL); - two = kmalloc(size, GFP_KERNEL); - if (!one || !two) { - pr_warn("Failed to allocate kernel memory\n"); - goto free_kernel; - } - - user_addr = vm_mmap(NULL, 0, PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (user_addr >= TASK_SIZE) { - pr_warn("Failed to allocate user memory\n"); - goto free_kernel; - } - - memset(one, 'A', size); - memset(two, 'B', size); - - if (to_user) { - pr_info("attempting good copy_to_user of correct size\n"); - if (copy_to_user((void __user *)user_addr, one, size)) { - pr_warn("copy_to_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_to_user of too large size\n"); - if (copy_to_user((void __user *)user_addr, one, 2 * size)) { - pr_warn("copy_to_user failed, but lacked Oops\n"); - goto free_user; - } - } else { - pr_info("attempting good copy_from_user of correct size\n"); - if (copy_from_user(one, (void __user *)user_addr, size)) { - pr_warn("copy_from_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_from_user of too large size\n"); - if (copy_from_user(one, (void __user *)user_addr, 2 * size)) { - pr_warn("copy_from_user failed, but lacked Oops\n"); - goto free_user; - } - } - -free_user: - vm_munmap(user_addr, PAGE_SIZE); -free_kernel: - kfree(one); - kfree(two); -} - -static void do_usercopy_heap_flag(bool to_user) -{ - unsigned long user_addr; - unsigned char *good_buf = NULL; - unsigned char *bad_buf = NULL; - - /* Make sure cache was prepared. */ - if (!bad_cache) { - pr_warn("Failed to allocate kernel cache\n"); - return; - } - - /* - * Allocate one buffer from each cache (kmalloc will have the - * SLAB_USERCOPY flag already, but "bad_cache" won't). - */ - good_buf = kmalloc(cache_size, GFP_KERNEL); - bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL); - if (!good_buf || !bad_buf) { - pr_warn("Failed to allocate buffers from caches\n"); - goto free_alloc; - } - - /* Allocate user memory we'll poke at. */ - user_addr = vm_mmap(NULL, 0, PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (user_addr >= TASK_SIZE) { - pr_warn("Failed to allocate user memory\n"); - goto free_alloc; - } - - memset(good_buf, 'A', cache_size); - memset(bad_buf, 'B', cache_size); - - if (to_user) { - pr_info("attempting good copy_to_user with SLAB_USERCOPY\n"); - if (copy_to_user((void __user *)user_addr, good_buf, - cache_size)) { - pr_warn("copy_to_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n"); - if (copy_to_user((void __user *)user_addr, bad_buf, - cache_size)) { - pr_warn("copy_to_user failed, but lacked Oops\n"); - goto free_user; - } - } else { - pr_info("attempting good copy_from_user with SLAB_USERCOPY\n"); - if (copy_from_user(good_buf, (void __user *)user_addr, - cache_size)) { - pr_warn("copy_from_user failed unexpectedly?!\n"); - goto free_user; - } - - pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n"); - if (copy_from_user(bad_buf, (void __user *)user_addr, - cache_size)) { - pr_warn("copy_from_user failed, but lacked Oops\n"); - goto free_user; - } - } - -free_user: - vm_munmap(user_addr, PAGE_SIZE); -free_alloc: - if (bad_buf) - kmem_cache_free(bad_cache, bad_buf); - kfree(good_buf); -} static void lkdtm_do_action(enum ctype which) { @@ -964,28 +711,28 @@ static void lkdtm_do_action(enum ctype which) return; } case CT_USERCOPY_HEAP_SIZE_TO: - do_usercopy_heap_size(true); + lkdtm_USERCOPY_HEAP_SIZE_TO(); break; case CT_USERCOPY_HEAP_SIZE_FROM: - do_usercopy_heap_size(false); + lkdtm_USERCOPY_HEAP_SIZE_FROM(); break; case CT_USERCOPY_HEAP_FLAG_TO: - do_usercopy_heap_flag(true); + lkdtm_USERCOPY_HEAP_FLAG_TO(); break; case CT_USERCOPY_HEAP_FLAG_FROM: - do_usercopy_heap_flag(false); + lkdtm_USERCOPY_HEAP_FLAG_FROM(); break; case CT_USERCOPY_STACK_FRAME_TO: - do_usercopy_stack(true, true); + lkdtm_USERCOPY_STACK_FRAME_TO(); break; case CT_USERCOPY_STACK_FRAME_FROM: - do_usercopy_stack(false, true); + lkdtm_USERCOPY_STACK_FRAME_FROM(); break; case CT_USERCOPY_STACK_BEYOND: - do_usercopy_stack(true, false); + lkdtm_USERCOPY_STACK_BEYOND(); break; case CT_USERCOPY_KERNEL: - do_usercopy_kernel(); + lkdtm_USERCOPY_KERNEL(); break; case CT_NONE: default: @@ -1276,13 +1023,12 @@ static int __init lkdtm_module_init(void) int n_debugfs_entries = 1; /* Assume only the direct entry */ int i; + /* Handle test-specific initialization. */ + lkdtm_usercopy_init(); + /* Make sure we can write to __ro_after_init values during __init */ ro_after_init |= 0xAA; - /* Prepare cache that lacks SLAB_USERCOPY flag. */ - bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0, - 0, NULL); - /* Register debugfs interface */ lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL); if (!lkdtm_debugfs_root) { @@ -1334,7 +1080,8 @@ static void __exit lkdtm_module_exit(void) { debugfs_remove_recursive(lkdtm_debugfs_root); - kmem_cache_destroy(bad_cache); + /* Handle test-specific clean-up. */ + lkdtm_usercopy_exit(); unregister_jprobe(&lkdtm); pr_info("Crash point unregistered\n"); diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c new file mode 100644 index 000000000000..9c748e819a35 --- /dev/null +++ b/drivers/misc/lkdtm_usercopy.c @@ -0,0 +1,315 @@ +/* + * This is for all the tests related to copy_to_user() and copy_from_user() + * hardening. + */ +#define pr_fmt(fmt) "lkdtm: " fmt + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/vmalloc.h> +#include <linux/mman.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> + +static size_t cache_size = 1024; +static struct kmem_cache *bad_cache; + +static const unsigned char test_text[] = "This is a test.\n"; + +/* + * Instead of adding -Wno-return-local-addr, just pass the stack address + * through a function to obfuscate it from the compiler. + */ +static noinline unsigned char *trick_compiler(unsigned char *stack) +{ + return stack + 0; +} + +static noinline unsigned char *do_usercopy_stack_callee(int value) +{ + unsigned char buf[32]; + int i; + + /* Exercise stack to avoid everything living in registers. */ + for (i = 0; i < sizeof(buf); i++) { + buf[i] = value & 0xff; + } + + return trick_compiler(buf); +} + +static noinline void do_usercopy_stack(bool to_user, bool bad_frame) +{ + unsigned long user_addr; + unsigned char good_stack[32]; + unsigned char *bad_stack; + int i; + + /* Exercise stack to avoid everything living in registers. */ + for (i = 0; i < sizeof(good_stack); i++) + good_stack[i] = test_text[i % sizeof(test_text)]; + + /* This is a pointer to outside our current stack frame. */ + if (bad_frame) { + bad_stack = do_usercopy_stack_callee((uintptr_t)bad_stack); + } else { + /* Put start address just inside stack. */ + bad_stack = task_stack_page(current) + THREAD_SIZE; + bad_stack -= sizeof(unsigned long); + } + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + if (to_user) { + pr_info("attempting good copy_to_user of local stack\n"); + if (copy_to_user((void __user *)user_addr, good_stack, + sizeof(good_stack))) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user of distant stack\n"); + if (copy_to_user((void __user *)user_addr, bad_stack, + sizeof(good_stack))) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + /* + * There isn't a safe way to not be protected by usercopy + * if we're going to write to another thread's stack. + */ + if (!bad_frame) + goto free_user; + + pr_info("attempting good copy_from_user of local stack\n"); + if (copy_from_user(good_stack, (void __user *)user_addr, + sizeof(good_stack))) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user of distant stack\n"); + if (copy_from_user(bad_stack, (void __user *)user_addr, + sizeof(good_stack))) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +} + +static void do_usercopy_heap_size(bool to_user) +{ + unsigned long user_addr; + unsigned char *one, *two; + const size_t size = 1024; + + one = kmalloc(size, GFP_KERNEL); + two = kmalloc(size, GFP_KERNEL); + if (!one || !two) { + pr_warn("Failed to allocate kernel memory\n"); + goto free_kernel; + } + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + goto free_kernel; + } + + memset(one, 'A', size); + memset(two, 'B', size); + + if (to_user) { + pr_info("attempting good copy_to_user of correct size\n"); + if (copy_to_user((void __user *)user_addr, one, size)) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user of too large size\n"); + if (copy_to_user((void __user *)user_addr, one, 2 * size)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + pr_info("attempting good copy_from_user of correct size\n"); + if (copy_from_user(one, (void __user *)user_addr, size)) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user of too large size\n"); + if (copy_from_user(one, (void __user *)user_addr, 2 * size)) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +free_kernel: + kfree(one); + kfree(two); +} + +static void do_usercopy_heap_flag(bool to_user) +{ + unsigned long user_addr; + unsigned char *good_buf = NULL; + unsigned char *bad_buf = NULL; + + /* Make sure cache was prepared. */ + if (!bad_cache) { + pr_warn("Failed to allocate kernel cache\n"); + return; + } + + /* + * Allocate one buffer from each cache (kmalloc will have the + * SLAB_USERCOPY flag already, but "bad_cache" won't). + */ + good_buf = kmalloc(cache_size, GFP_KERNEL); + bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL); + if (!good_buf || !bad_buf) { + pr_warn("Failed to allocate buffers from caches\n"); + goto free_alloc; + } + + /* Allocate user memory we'll poke at. */ + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + goto free_alloc; + } + + memset(good_buf, 'A', cache_size); + memset(bad_buf, 'B', cache_size); + + if (to_user) { + pr_info("attempting good copy_to_user with SLAB_USERCOPY\n"); + if (copy_to_user((void __user *)user_addr, good_buf, + cache_size)) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n"); + if (copy_to_user((void __user *)user_addr, bad_buf, + cache_size)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + pr_info("attempting good copy_from_user with SLAB_USERCOPY\n"); + if (copy_from_user(good_buf, (void __user *)user_addr, + cache_size)) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n"); + if (copy_from_user(bad_buf, (void __user *)user_addr, + cache_size)) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +free_alloc: + if (bad_buf) + kmem_cache_free(bad_cache, bad_buf); + kfree(good_buf); +} + +/* Callable tests. */ +void lkdtm_USERCOPY_HEAP_SIZE_TO(void) +{ + do_usercopy_heap_size(true); +} + +void lkdtm_USERCOPY_HEAP_SIZE_FROM(void) +{ + do_usercopy_heap_size(false); +} + +void lkdtm_USERCOPY_HEAP_FLAG_TO(void) +{ + do_usercopy_heap_flag(true); +} + +void lkdtm_USERCOPY_HEAP_FLAG_FROM(void) +{ + do_usercopy_heap_flag(false); +} + +void lkdtm_USERCOPY_STACK_FRAME_TO(void) +{ + do_usercopy_stack(true, true); +} + +void lkdtm_USERCOPY_STACK_FRAME_FROM(void) +{ + do_usercopy_stack(false, true); +} + +void lkdtm_USERCOPY_STACK_BEYOND(void) +{ + do_usercopy_stack(true, false); +} + +void lkdtm_USERCOPY_KERNEL(void) +{ + unsigned long user_addr; + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + pr_info("attempting good copy_to_user from kernel rodata\n"); + if (copy_to_user((void __user *)user_addr, test_text, + sizeof(test_text))) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user from kernel text\n"); + if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +} + +void __init lkdtm_usercopy_init(void) +{ + /* Prepare cache that lacks SLAB_USERCOPY flag. */ + bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0, + 0, NULL); +} + +void __exit lkdtm_usercopy_exit(void) +{ + kmem_cache_destroy(bad_cache); +} |