From 9ae113ce5faf1c74af1ee71b5ef7d04b6b06b063 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 24 Oct 2013 09:25:57 -0700 Subject: [PATCH] lkdtm: add tests for additional page permissions Testing execution and access of userspace from the kernel is needed for validating things like Intel's SMEP and SMAP protections. Additionally, add an explicit test for validating that RO page permissions have been set for the RO data area. Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- drivers/misc/lkdtm.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index 4823442..a2edb2e 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -44,6 +44,7 @@ #include #include #include +#include #ifdef CONFIG_IDE #include @@ -97,6 +98,9 @@ enum ctype { CT_EXEC_STACK, CT_EXEC_KMALLOC, CT_EXEC_VMALLOC, + CT_EXEC_USERSPACE, + CT_ACCESS_USERSPACE, + CT_WRITE_RO, }; static char* cp_name[] = { @@ -130,6 +134,9 @@ static char* cp_type[] = { "EXEC_STACK", "EXEC_KMALLOC", "EXEC_VMALLOC", + "EXEC_USERSPACE", + "ACCESS_USERSPACE", + "WRITE_RO", }; static struct jprobe lkdtm; @@ -150,6 +157,8 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; +static const unsigned long rodata = 0xAA55AA55; + module_param(recur_count, int, 0644); MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); module_param(cpoint_name, charp, 0444); @@ -323,6 +332,15 @@ static void execute_location(void *dst) func(); } +static void execute_user_location(void *dst) +{ + void (*func)(void) = dst; + + if (copy_to_user(dst, do_nothing, EXEC_SIZE)) + return; + func(); +} + static void lkdtm_do_action(enum ctype which) { switch (which) { @@ -415,6 +433,49 @@ static void lkdtm_do_action(enum ctype which) vfree(vmalloc_area); break; } + case CT_EXEC_USERSPACE: { + 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; + } + execute_user_location((void *)user_addr); + vm_munmap(user_addr, PAGE_SIZE); + break; + } + case CT_ACCESS_USERSPACE: { + unsigned long user_addr, tmp; + unsigned long *ptr; + + 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; + } + + ptr = (unsigned long *)user_addr; + tmp = *ptr; + tmp += 0xc0dec0de; + *ptr = tmp; + + vm_munmap(user_addr, PAGE_SIZE); + + break; + } + case CT_WRITE_RO: { + unsigned long *ptr; + + ptr = (unsigned long *)&rodata; + *ptr ^= 0xabcd1234; + + break; + } case CT_NONE: default: break; -- 2.7.4