This splits the *_AFTER_FREE and related tests into the new lkdtm_heap.c file to help separate things better for readability.
Signed-off-by: Kees Cook <[email protected]> --- drivers/misc/Makefile | 1 + drivers/misc/lkdtm.h | 7 +++ drivers/misc/lkdtm_core.c | 124 ++++----------------------------------- drivers/misc/lkdtm_heap.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 164 insertions(+), 114 deletions(-) create mode 100644 drivers/misc/lkdtm_heap.c diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 9f6e95bc0635..d66f657cf9f2 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -59,6 +59,7 @@ obj-$(CONFIG_CXL_BASE) += cxl/ obj-$(CONFIG_PANEL) += panel.o lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o +lkdtm-$(CONFIG_LKDTM) += lkdtm_heap.o lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h index 40f681cd6efe..9397360a2b11 100644 --- a/drivers/misc/lkdtm.h +++ b/drivers/misc/lkdtm.h @@ -1,6 +1,13 @@ #ifndef __LKDTM_H #define __LKDTM_H +/* lkdtm_heap.c */ +void lkdtm_OVERWRITE_ALLOCATION(void); +void lkdtm_WRITE_AFTER_FREE(void); +void lkdtm_READ_AFTER_FREE(void); +void lkdtm_WRITE_BUDDY_AFTER_FREE(void); +void lkdtm_READ_BUDDY_AFTER_FREE(void); + /* lkdtm_perms.c */ void __init lkdtm_perms_init(void); void lkdtm_WRITE_RO(void); diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index 0b3e3770068a..1c5056c286c5 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -384,125 +384,21 @@ static void lkdtm_do_action(enum ctype which) *p = val; break; } - case CT_OVERWRITE_ALLOCATION: { - size_t len = 1020; - u32 *data = kmalloc(len, GFP_KERNEL); - - data[1024 / sizeof(u32)] = 0x12345678; - kfree(data); + case CT_OVERWRITE_ALLOCATION: + lkdtm_OVERWRITE_ALLOCATION(); break; - } - case CT_WRITE_AFTER_FREE: { - int *base, *again; - size_t len = 1024; - /* - * The slub allocator uses the first word to store the free - * pointer in some configurations. Use the middle of the - * allocation to avoid running into the freelist - */ - size_t offset = (len / sizeof(*base)) / 2; - - base = kmalloc(len, GFP_KERNEL); - pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]); - pr_info("Attempting bad write to freed memory at %p\n", - &base[offset]); - kfree(base); - base[offset] = 0x0abcdef0; - /* Attempt to notice the overwrite. */ - again = kmalloc(len, GFP_KERNEL); - kfree(again); - if (again != base) - pr_info("Hmm, didn't get the same memory range.\n"); - + case CT_WRITE_AFTER_FREE: + lkdtm_WRITE_AFTER_FREE(); break; - } - case CT_READ_AFTER_FREE: { - int *base, *val, saw; - size_t len = 1024; - /* - * The slub allocator uses the first word to store the free - * pointer in some configurations. Use the middle of the - * allocation to avoid running into the freelist - */ - size_t offset = (len / sizeof(*base)) / 2; - - base = kmalloc(len, GFP_KERNEL); - if (!base) - break; - - val = kmalloc(len, GFP_KERNEL); - if (!val) { - kfree(base); - break; - } - - *val = 0x12345678; - base[offset] = *val; - pr_info("Value in memory before free: %x\n", base[offset]); - - kfree(base); - - pr_info("Attempting bad read from freed memory\n"); - saw = base[offset]; - if (saw != *val) { - /* Good! Poisoning happened, so declare a win. */ - pr_info("Memory correctly poisoned (%x)\n", saw); - BUG(); - } - pr_info("Memory was not poisoned\n"); - - kfree(val); + case CT_READ_AFTER_FREE: + lkdtm_READ_AFTER_FREE(); break; - } - case CT_WRITE_BUDDY_AFTER_FREE: { - unsigned long p = __get_free_page(GFP_KERNEL); - if (!p) - break; - pr_info("Writing to the buddy page before free\n"); - memset((void *)p, 0x3, PAGE_SIZE); - free_page(p); - schedule(); - pr_info("Attempting bad write to the buddy page after free\n"); - memset((void *)p, 0x78, PAGE_SIZE); - /* Attempt to notice the overwrite. */ - p = __get_free_page(GFP_KERNEL); - free_page(p); - schedule(); - + case CT_WRITE_BUDDY_AFTER_FREE: + lkdtm_WRITE_BUDDY_AFTER_FREE(); break; - } - case CT_READ_BUDDY_AFTER_FREE: { - unsigned long p = __get_free_page(GFP_KERNEL); - int saw, *val; - int *base; - - if (!p) - break; - - val = kmalloc(1024, GFP_KERNEL); - if (!val) { - free_page(p); - break; - } - - base = (int *)p; - - *val = 0x12345678; - base[0] = *val; - pr_info("Value in memory before free: %x\n", base[0]); - free_page(p); - pr_info("Attempting to read from freed memory\n"); - saw = base[0]; - if (saw != *val) { - /* Good! Poisoning happened, so declare a win. */ - pr_info("Memory correctly poisoned (%x)\n", saw); - BUG(); - } - pr_info("Buddy page was not poisoned\n"); - - kfree(val); + case CT_READ_BUDDY_AFTER_FREE: + lkdtm_READ_BUDDY_AFTER_FREE(); break; - } case CT_SOFTLOCKUP: preempt_disable(); for (;;) diff --git a/drivers/misc/lkdtm_heap.c b/drivers/misc/lkdtm_heap.c new file mode 100644 index 000000000000..12f50e8dcbfe --- /dev/null +++ b/drivers/misc/lkdtm_heap.c @@ -0,0 +1,146 @@ +/* + * This is for all the tests relating directly to heap memory, including + * page allocation and slab allocations. + */ +#define pr_fmt(fmt) "lkdtm: " fmt + +#include <linux/kernel.h> +#include <linux/slab.h> + +#include "lkdtm.h" + +/* + * This tries to stay within the next largest power-of-2 kmalloc cache + * to avoid actually overwriting anything important if it's not detected + * correctly. + */ +void lkdtm_OVERWRITE_ALLOCATION(void) +{ + size_t len = 1020; + u32 *data = kmalloc(len, GFP_KERNEL); + + data[1024 / sizeof(u32)] = 0x12345678; + kfree(data); +} + +void lkdtm_WRITE_AFTER_FREE(void) +{ + int *base, *again; + size_t len = 1024; + /* + * The slub allocator uses the first word to store the free + * pointer in some configurations. Use the middle of the + * allocation to avoid running into the freelist + */ + size_t offset = (len / sizeof(*base)) / 2; + + base = kmalloc(len, GFP_KERNEL); + pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]); + pr_info("Attempting bad write to freed memory at %p\n", + &base[offset]); + kfree(base); + base[offset] = 0x0abcdef0; + /* Attempt to notice the overwrite. */ + again = kmalloc(len, GFP_KERNEL); + kfree(again); + if (again != base) + pr_info("Hmm, didn't get the same memory range.\n"); +} + +void lkdtm_READ_AFTER_FREE(void) +{ + int *base, *val, saw; + size_t len = 1024; + /* + * The slub allocator uses the first word to store the free + * pointer in some configurations. Use the middle of the + * allocation to avoid running into the freelist + */ + size_t offset = (len / sizeof(*base)) / 2; + + base = kmalloc(len, GFP_KERNEL); + if (!base) { + pr_info("Unable to allocate base memory.\n"); + return; + } + + val = kmalloc(len, GFP_KERNEL); + if (!val) { + pr_info("Unable to allocate val memory.\n"); + kfree(base); + return; + } + + *val = 0x12345678; + base[offset] = *val; + pr_info("Value in memory before free: %x\n", base[offset]); + + kfree(base); + + pr_info("Attempting bad read from freed memory\n"); + saw = base[offset]; + if (saw != *val) { + /* Good! Poisoning happened, so declare a win. */ + pr_info("Memory correctly poisoned (%x)\n", saw); + BUG(); + } + pr_info("Memory was not poisoned\n"); + + kfree(val); +} + +void lkdtm_WRITE_BUDDY_AFTER_FREE(void) +{ + unsigned long p = __get_free_page(GFP_KERNEL); + if (!p) { + pr_info("Unable to allocate free page\n"); + return; + } + + pr_info("Writing to the buddy page before free\n"); + memset((void *)p, 0x3, PAGE_SIZE); + free_page(p); + schedule(); + pr_info("Attempting bad write to the buddy page after free\n"); + memset((void *)p, 0x78, PAGE_SIZE); + /* Attempt to notice the overwrite. */ + p = __get_free_page(GFP_KERNEL); + free_page(p); + schedule(); +} + +void lkdtm_READ_BUDDY_AFTER_FREE(void) +{ + unsigned long p = __get_free_page(GFP_KERNEL); + int saw, *val; + int *base; + + if (!p) { + pr_info("Unable to allocate free page\n"); + return; + } + + val = kmalloc(1024, GFP_KERNEL); + if (!val) { + pr_info("Unable to allocate val memory.\n"); + free_page(p); + return; + } + + base = (int *)p; + + *val = 0x12345678; + base[0] = *val; + pr_info("Value in memory before free: %x\n", base[0]); + free_page(p); + pr_info("Attempting to read from freed memory\n"); + saw = base[0]; + if (saw != *val) { + /* Good! Poisoning happened, so declare a win. */ + pr_info("Memory correctly poisoned (%x)\n", saw); + BUG(); + } + pr_info("Buddy page was not poisoned\n"); + + kfree(val); +} -- 2.7.4
