diff options
Diffstat (limited to 'drivers/misc/lkdtm/perms.c')
| -rw-r--r-- | drivers/misc/lkdtm/perms.c | 71 |
1 files changed, 57 insertions, 14 deletions
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c index 2dede2ef658f..2c6aba3ff32b 100644 --- a/drivers/misc/lkdtm/perms.c +++ b/drivers/misc/lkdtm/perms.c @@ -10,6 +10,7 @@ #include <linux/mman.h> #include <linux/uaccess.h> #include <asm/cacheflush.h> +#include <asm/sections.h> /* Whether or not to fill the target memory area with do_nothing(). */ #define CODE_WRITE true @@ -21,7 +22,7 @@ /* This is non-const, so it will end up in the .data section. */ static u8 data_area[EXEC_SIZE]; -/* This is cost, so it will end up in the .rodata section. */ +/* This is const, so it will end up in the .rodata section. */ static const unsigned long rodata = 0xAA55AA55; /* This is marked __ro_after_init, so it should ultimately be .rodata. */ @@ -31,31 +32,51 @@ static unsigned long ro_after_init __ro_after_init = 0x55AA5500; * This just returns to the caller. It is designed to be copied into * non-executable memory regions. */ -static void do_nothing(void) +static noinline void do_nothing(void) { return; } /* Must immediately follow do_nothing for size calculuations to work out. */ -static void do_overwritten(void) +static noinline void do_overwritten(void) { pr_info("do_overwritten wasn't overwritten!\n"); return; } +static noinline void do_almost_nothing(void) +{ + pr_info("do_nothing was hijacked!\n"); +} + +static void *setup_function_descriptor(func_desc_t *fdesc, void *dst) +{ + if (!have_function_descriptors()) + return dst; + + memcpy(fdesc, do_nothing, sizeof(*fdesc)); + fdesc->addr = (unsigned long)dst; + barrier(); + + return fdesc; +} + static noinline void execute_location(void *dst, bool write) { - void (*func)(void) = dst; + void (*func)(void); + func_desc_t fdesc; + void *do_nothing_text = dereference_function_descriptor(do_nothing); - pr_info("attempting ok execution at %px\n", do_nothing); + pr_info("attempting ok execution at %px\n", do_nothing_text); do_nothing(); if (write == CODE_WRITE) { - memcpy(dst, do_nothing, EXEC_SIZE); + memcpy(dst, do_nothing_text, EXEC_SIZE); flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE); } - pr_info("attempting bad execution at %px\n", func); + pr_info("attempting bad execution at %px\n", dst); + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } @@ -65,16 +86,19 @@ static void execute_user_location(void *dst) int copied; /* Intentionally crossing kernel/user memory boundary. */ - void (*func)(void) = dst; + void (*func)(void); + func_desc_t fdesc; + void *do_nothing_text = dereference_function_descriptor(do_nothing); - pr_info("attempting ok execution at %px\n", do_nothing); + pr_info("attempting ok execution at %px\n", do_nothing_text); do_nothing(); - copied = access_process_vm(current, (unsigned long)dst, do_nothing, + copied = access_process_vm(current, (unsigned long)dst, do_nothing_text, EXEC_SIZE, FOLL_WRITE); if (copied < EXEC_SIZE) return; - pr_info("attempting bad execution at %px\n", func); + pr_info("attempting bad execution at %px\n", dst); + func = setup_function_descriptor(&fdesc, dst); func(); pr_err("FAIL: func returned\n"); } @@ -113,8 +137,9 @@ void lkdtm_WRITE_KERN(void) size_t size; volatile unsigned char *ptr; - size = (unsigned long)do_overwritten - (unsigned long)do_nothing; - ptr = (unsigned char *)do_overwritten; + size = (unsigned long)dereference_function_descriptor(do_overwritten) - + (unsigned long)dereference_function_descriptor(do_nothing); + ptr = dereference_function_descriptor(do_overwritten); pr_info("attempting bad %zu byte write at %px\n", size, ptr); memcpy((void *)ptr, (unsigned char *)do_nothing, size); @@ -124,6 +149,23 @@ void lkdtm_WRITE_KERN(void) do_overwritten(); } +void lkdtm_WRITE_OPD(void) +{ + size_t size = sizeof(func_desc_t); + void (*func)(void) = do_nothing; + + if (!have_function_descriptors()) { + pr_info("XFAIL: Platform doesn't use function descriptors.\n"); + return; + } + pr_info("attempting bad %zu bytes write at %px\n", size, do_nothing); + memcpy(do_nothing, do_almost_nothing, size); + pr_err("FAIL: survived bad write\n"); + + asm("" : "=m"(func)); + func(); +} + void lkdtm_EXEC_DATA(void) { execute_location(data_area, CODE_WRITE); @@ -151,7 +193,8 @@ void lkdtm_EXEC_VMALLOC(void) void lkdtm_EXEC_RODATA(void) { - execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); + execute_location(dereference_function_descriptor(lkdtm_rodata_do_nothing), + CODE_AS_IS); } void lkdtm_EXEC_USERSPACE(void) |