From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- drivers/misc/lkdtm/perms.c | 293 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 293 insertions(+) create mode 100644 drivers/misc/lkdtm/perms.c (limited to 'drivers/misc/lkdtm/perms.c') diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c new file mode 100644 index 000000000..b93404d65 --- /dev/null +++ b/drivers/misc/lkdtm/perms.c @@ -0,0 +1,293 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is for all the tests related to validating kernel memory + * permissions: non-executable regions, non-writable regions, and + * even non-readable regions. + */ +#include "lkdtm.h" +#include +#include +#include +#include +#include +#include + +/* Whether or not to fill the target memory area with do_nothing(). */ +#define CODE_WRITE true +#define CODE_AS_IS false + +/* How many bytes to copy to be sure we've copied enough of do_nothing(). */ +#define EXEC_SIZE 64 + +/* This is non-const, so it will end up in the .data section. */ +static u8 data_area[EXEC_SIZE]; + +/* 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. */ +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 noinline void do_nothing(void) +{ + return; +} + +/* Must immediately follow do_nothing for size calculuations to work out. */ +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); + func_desc_t fdesc; + void *do_nothing_text = dereference_function_descriptor(do_nothing); + + pr_info("attempting ok execution at %px\n", do_nothing_text); + do_nothing(); + + if (write == CODE_WRITE) { + 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", dst); + func = setup_function_descriptor(&fdesc, dst); + func(); + pr_err("FAIL: func returned\n"); +} + +static void execute_user_location(void *dst) +{ + int copied; + + /* Intentionally crossing kernel/user memory boundary. */ + 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_text); + 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", dst); + func = setup_function_descriptor(&fdesc, dst); + func(); + pr_err("FAIL: func returned\n"); +} + +static void lkdtm_WRITE_RO(void) +{ + /* Explicitly cast away "const" for the test and make volatile. */ + volatile unsigned long *ptr = (unsigned long *)&rodata; + + pr_info("attempting bad rodata write at %px\n", ptr); + *ptr ^= 0xabcd1234; + pr_err("FAIL: survived bad write\n"); +} + +static void lkdtm_WRITE_RO_AFTER_INIT(void) +{ + volatile unsigned long *ptr = &ro_after_init; + + /* + * Verify we were written to during init. Since an Oops + * is considered a "success", a failure is to just skip the + * real test. + */ + if ((*ptr & 0xAA) != 0xAA) { + pr_info("%p was NOT written during init!?\n", ptr); + return; + } + + pr_info("attempting bad ro_after_init write at %px\n", ptr); + *ptr ^= 0xabcd1234; + pr_err("FAIL: survived bad write\n"); +} + +static void lkdtm_WRITE_KERN(void) +{ + size_t size; + volatile unsigned char *ptr; + + 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); + flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size)); + pr_err("FAIL: survived bad write\n"); + + do_overwritten(); +} + +static 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(); +} + +static void lkdtm_EXEC_DATA(void) +{ + execute_location(data_area, CODE_WRITE); +} + +static void lkdtm_EXEC_STACK(void) +{ + u8 stack_area[EXEC_SIZE]; + execute_location(stack_area, CODE_WRITE); +} + +static void lkdtm_EXEC_KMALLOC(void) +{ + u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL); + execute_location(kmalloc_area, CODE_WRITE); + kfree(kmalloc_area); +} + +static void lkdtm_EXEC_VMALLOC(void) +{ + u32 *vmalloc_area = vmalloc(EXEC_SIZE); + execute_location(vmalloc_area, CODE_WRITE); + vfree(vmalloc_area); +} + +static void lkdtm_EXEC_RODATA(void) +{ + execute_location(dereference_function_descriptor(lkdtm_rodata_do_nothing), + CODE_AS_IS); +} + +static void lkdtm_EXEC_USERSPACE(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; + } + execute_user_location((void *)user_addr); + vm_munmap(user_addr, PAGE_SIZE); +} + +static void lkdtm_EXEC_NULL(void) +{ + execute_location(NULL, CODE_AS_IS); +} + +static void lkdtm_ACCESS_USERSPACE(void) +{ + unsigned long user_addr, tmp = 0; + 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; + } + + if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) { + pr_warn("copy_to_user failed\n"); + vm_munmap(user_addr, PAGE_SIZE); + return; + } + + ptr = (unsigned long *)user_addr; + + pr_info("attempting bad read at %px\n", ptr); + tmp = *ptr; + tmp += 0xc0dec0de; + pr_err("FAIL: survived bad read\n"); + + pr_info("attempting bad write at %px\n", ptr); + *ptr = tmp; + pr_err("FAIL: survived bad write\n"); + + vm_munmap(user_addr, PAGE_SIZE); +} + +static void lkdtm_ACCESS_NULL(void) +{ + unsigned long tmp; + volatile unsigned long *ptr = (unsigned long *)NULL; + + pr_info("attempting bad read at %px\n", ptr); + tmp = *ptr; + tmp += 0xc0dec0de; + pr_err("FAIL: survived bad read\n"); + + pr_info("attempting bad write at %px\n", ptr); + *ptr = tmp; + pr_err("FAIL: survived bad write\n"); +} + +void __init lkdtm_perms_init(void) +{ + /* Make sure we can write to __ro_after_init values during __init */ + ro_after_init |= 0xAA; +} + +static struct crashtype crashtypes[] = { + CRASHTYPE(WRITE_RO), + CRASHTYPE(WRITE_RO_AFTER_INIT), + CRASHTYPE(WRITE_KERN), + CRASHTYPE(WRITE_OPD), + CRASHTYPE(EXEC_DATA), + CRASHTYPE(EXEC_STACK), + CRASHTYPE(EXEC_KMALLOC), + CRASHTYPE(EXEC_VMALLOC), + CRASHTYPE(EXEC_RODATA), + CRASHTYPE(EXEC_USERSPACE), + CRASHTYPE(EXEC_NULL), + CRASHTYPE(ACCESS_USERSPACE), + CRASHTYPE(ACCESS_NULL), +}; + +struct crashtype_category perms_crashtypes = { + .crashtypes = crashtypes, + .len = ARRAY_SIZE(crashtypes), +}; -- cgit v1.2.3