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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 | // 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 <linux/slab.h> #include <linux/vmalloc.h> #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 #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 __nocfi 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), }; |