1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_FORTIFY_STRING_H_ 3 #define _LINUX_FORTIFY_STRING_H_ 4 5 #include <linux/bug.h> 6 #include <linux/const.h> 7 #include <linux/limits.h> 8 9 #define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable 10 #define __RENAME(x) __asm__(#x) 11 12 void fortify_panic(const char *name) __noreturn __cold; 13 void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)"); 14 void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)"); 15 void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?"); 16 void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)"); 17 void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?"); 18 19 #define __compiletime_strlen(p) \ 20 ({ \ 21 unsigned char *__p = (unsigned char *)(p); \ 22 size_t __ret = SIZE_MAX; \ 23 size_t __p_size = __member_size(p); \ 24 if (__p_size != SIZE_MAX && \ 25 __builtin_constant_p(*__p)) { \ 26 size_t __p_len = __p_size - 1; \ 27 if (__builtin_constant_p(__p[__p_len]) && \ 28 __p[__p_len] == '\0') \ 29 __ret = __builtin_strlen(__p); \ 30 } \ 31 __ret; \ 32 }) 33 34 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) 35 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr); 36 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp); 37 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy); 38 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove); 39 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset); 40 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat); 41 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy); 42 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen); 43 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat); 44 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy); 45 #else 46 #define __underlying_memchr __builtin_memchr 47 #define __underlying_memcmp __builtin_memcmp 48 #define __underlying_memcpy __builtin_memcpy 49 #define __underlying_memmove __builtin_memmove 50 #define __underlying_memset __builtin_memset 51 #define __underlying_strcat __builtin_strcat 52 #define __underlying_strcpy __builtin_strcpy 53 #define __underlying_strlen __builtin_strlen 54 #define __underlying_strncat __builtin_strncat 55 #define __underlying_strncpy __builtin_strncpy 56 #endif 57 58 /** 59 * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking 60 * 61 * @dst: Destination memory address to write to 62 * @src: Source memory address to read from 63 * @bytes: How many bytes to write to @dst from @src 64 * @justification: Free-form text or comment describing why the use is needed 65 * 66 * This should be used for corner cases where the compiler cannot do the 67 * right thing, or during transitions between APIs, etc. It should be used 68 * very rarely, and includes a place for justification detailing where bounds 69 * checking has happened, and why existing solutions cannot be employed. 70 */ 71 #define unsafe_memcpy(dst, src, bytes, justification) \ 72 __underlying_memcpy(dst, src, bytes) 73 74 /* 75 * Clang's use of __builtin_*object_size() within inlines needs hinting via 76 * __pass_*object_size(). The preference is to only ever use type 1 (member 77 * size, rather than struct size), but there remain some stragglers using 78 * type 0 that will be converted in the future. 79 */ 80 #define POS __pass_object_size(1) 81 #define POS0 __pass_object_size(0) 82 #define __struct_size(p) __builtin_object_size(p, 0) 83 #define __member_size(p) __builtin_object_size(p, 1) 84 85 #define __compiletime_lessthan(bounds, length) ( \ 86 __builtin_constant_p((bounds) < (length)) && \ 87 (bounds) < (length) \ 88 ) 89 90 /** 91 * strncpy - Copy a string to memory with non-guaranteed NUL padding 92 * 93 * @p: pointer to destination of copy 94 * @q: pointer to NUL-terminated source string to copy 95 * @size: bytes to write at @p 96 * 97 * If strlen(@q) >= @size, the copy of @q will stop after @size bytes, 98 * and @p will NOT be NUL-terminated 99 * 100 * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes 101 * will be written to @p until @size total bytes have been written. 102 * 103 * Do not use this function. While FORTIFY_SOURCE tries to avoid 104 * over-reads of @q, it cannot defend against writing unterminated 105 * results to @p. Using strncpy() remains ambiguous and fragile. 106 * Instead, please choose an alternative, so that the expectation 107 * of @p's contents is unambiguous: 108 * 109 * +--------------------+--------------------+------------+ 110 * | **p** needs to be: | padded to **size** | not padded | 111 * +====================+====================+============+ 112 * | NUL-terminated | strscpy_pad() | strscpy() | 113 * +--------------------+--------------------+------------+ 114 * | not NUL-terminated | strtomem_pad() | strtomem() | 115 * +--------------------+--------------------+------------+ 116 * 117 * Note strscpy*()'s differing return values for detecting truncation, 118 * and strtomem*()'s expectation that the destination is marked with 119 * __nonstring when it is a character array. 120 * 121 */ 122 __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3) 123 char *strncpy(char * const POS p, const char *q, __kernel_size_t size) 124 { 125 size_t p_size = __member_size(p); 126 127 if (__compiletime_lessthan(p_size, size)) 128 __write_overflow(); 129 if (p_size < size) 130 fortify_panic(__func__); 131 return __underlying_strncpy(p, q, size); 132 } 133 134 /** 135 * strcat - Append a string to an existing string 136 * 137 * @p: pointer to NUL-terminated string to append to 138 * @q: pointer to NUL-terminated source string to append from 139 * 140 * Do not use this function. While FORTIFY_SOURCE tries to avoid 141 * read and write overflows, this is only possible when the 142 * destination buffer size is known to the compiler. Prefer 143 * building the string with formatting, via scnprintf() or similar. 144 * At the very least, use strncat(). 145 * 146 * Returns @p. 147 * 148 */ 149 __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2) 150 char *strcat(char * const POS p, const char *q) 151 { 152 size_t p_size = __member_size(p); 153 154 if (p_size == SIZE_MAX) 155 return __underlying_strcat(p, q); 156 if (strlcat(p, q, p_size) >= p_size) 157 fortify_panic(__func__); 158 return p; 159 } 160 161 extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); 162 /** 163 * strnlen - Return bounded count of characters in a NUL-terminated string 164 * 165 * @p: pointer to NUL-terminated string to count. 166 * @maxlen: maximum number of characters to count. 167 * 168 * Returns number of characters in @p (NOT including the final NUL), or 169 * @maxlen, if no NUL has been found up to there. 170 * 171 */ 172 __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen) 173 { 174 size_t p_size = __member_size(p); 175 size_t p_len = __compiletime_strlen(p); 176 size_t ret; 177 178 /* We can take compile-time actions when maxlen is const. */ 179 if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) { 180 /* If p is const, we can use its compile-time-known len. */ 181 if (maxlen >= p_size) 182 return p_len; 183 } 184 185 /* Do not check characters beyond the end of p. */ 186 ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size); 187 if (p_size <= ret && maxlen != ret) 188 fortify_panic(__func__); 189 return ret; 190 } 191 192 /* 193 * Defined after fortified strnlen to reuse it. However, it must still be 194 * possible for strlen() to be used on compile-time strings for use in 195 * static initializers (i.e. as a constant expression). 196 */ 197 /** 198 * strlen - Return count of characters in a NUL-terminated string 199 * 200 * @p: pointer to NUL-terminated string to count. 201 * 202 * Do not use this function unless the string length is known at 203 * compile-time. When @p is unterminated, this function may crash 204 * or return unexpected counts that could lead to memory content 205 * exposures. Prefer strnlen(). 206 * 207 * Returns number of characters in @p (NOT including the final NUL). 208 * 209 */ 210 #define strlen(p) \ 211 __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)), \ 212 __builtin_strlen(p), __fortify_strlen(p)) 213 __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) 214 __kernel_size_t __fortify_strlen(const char * const POS p) 215 { 216 __kernel_size_t ret; 217 size_t p_size = __member_size(p); 218 219 /* Give up if we don't know how large p is. */ 220 if (p_size == SIZE_MAX) 221 return __underlying_strlen(p); 222 ret = strnlen(p, p_size); 223 if (p_size <= ret) 224 fortify_panic(__func__); 225 return ret; 226 } 227 228 /* Defined after fortified strlen() to reuse it. */ 229 extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy); 230 /** 231 * strlcpy - Copy a string into another string buffer 232 * 233 * @p: pointer to destination of copy 234 * @q: pointer to NUL-terminated source string to copy 235 * @size: maximum number of bytes to write at @p 236 * 237 * If strlen(@q) >= @size, the copy of @q will be truncated at 238 * @size - 1 bytes. @p will always be NUL-terminated. 239 * 240 * Do not use this function. While FORTIFY_SOURCE tries to avoid 241 * over-reads when calculating strlen(@q), it is still possible. 242 * Prefer strscpy(), though note its different return values for 243 * detecting truncation. 244 * 245 * Returns total number of bytes written to @p, including terminating NUL. 246 * 247 */ 248 __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size) 249 { 250 size_t p_size = __member_size(p); 251 size_t q_size = __member_size(q); 252 size_t q_len; /* Full count of source string length. */ 253 size_t len; /* Count of characters going into destination. */ 254 255 if (p_size == SIZE_MAX && q_size == SIZE_MAX) 256 return __real_strlcpy(p, q, size); 257 q_len = strlen(q); 258 len = (q_len >= size) ? size - 1 : q_len; 259 if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) { 260 /* Write size is always larger than destination. */ 261 if (len >= p_size) 262 __write_overflow(); 263 } 264 if (size) { 265 if (len >= p_size) 266 fortify_panic(__func__); 267 __underlying_memcpy(p, q, len); 268 p[len] = '\0'; 269 } 270 return q_len; 271 } 272 273 /* Defined after fortified strnlen() to reuse it. */ 274 extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy); 275 /** 276 * strscpy - Copy a C-string into a sized buffer 277 * 278 * @p: Where to copy the string to 279 * @q: Where to copy the string from 280 * @size: Size of destination buffer 281 * 282 * Copy the source string @p, or as much of it as fits, into the destination 283 * @q buffer. The behavior is undefined if the string buffers overlap. The 284 * destination @p buffer is always NUL terminated, unless it's zero-sized. 285 * 286 * Preferred to strlcpy() since the API doesn't require reading memory 287 * from the source @q string beyond the specified @size bytes, and since 288 * the return value is easier to error-check than strlcpy()'s. 289 * In addition, the implementation is robust to the string changing out 290 * from underneath it, unlike the current strlcpy() implementation. 291 * 292 * Preferred to strncpy() since it always returns a valid string, and 293 * doesn't unnecessarily force the tail of the destination buffer to be 294 * zero padded. If padding is desired please use strscpy_pad(). 295 * 296 * Returns the number of characters copied in @p (not including the 297 * trailing %NUL) or -E2BIG if @size is 0 or the copy of @q was truncated. 298 */ 299 __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, size_t size) 300 { 301 size_t len; 302 /* Use string size rather than possible enclosing struct size. */ 303 size_t p_size = __member_size(p); 304 size_t q_size = __member_size(q); 305 306 /* If we cannot get size of p and q default to call strscpy. */ 307 if (p_size == SIZE_MAX && q_size == SIZE_MAX) 308 return __real_strscpy(p, q, size); 309 310 /* 311 * If size can be known at compile time and is greater than 312 * p_size, generate a compile time write overflow error. 313 */ 314 if (__compiletime_lessthan(p_size, size)) 315 __write_overflow(); 316 317 /* Short-circuit for compile-time known-safe lengths. */ 318 if (__compiletime_lessthan(p_size, SIZE_MAX)) { 319 len = __compiletime_strlen(q); 320 321 if (len < SIZE_MAX && __compiletime_lessthan(len, size)) { 322 __underlying_memcpy(p, q, len + 1); 323 return len; 324 } 325 } 326 327 /* 328 * This call protects from read overflow, because len will default to q 329 * length if it smaller than size. 330 */ 331 len = strnlen(q, size); 332 /* 333 * If len equals size, we will copy only size bytes which leads to 334 * -E2BIG being returned. 335 * Otherwise we will copy len + 1 because of the final '\O'. 336 */ 337 len = len == size ? size : len + 1; 338 339 /* 340 * Generate a runtime write overflow error if len is greater than 341 * p_size. 342 */ 343 if (len > p_size) 344 fortify_panic(__func__); 345 346 /* 347 * We can now safely call vanilla strscpy because we are protected from: 348 * 1. Read overflow thanks to call to strnlen(). 349 * 2. Write overflow thanks to above ifs. 350 */ 351 return __real_strscpy(p, q, len); 352 } 353 354 /** 355 * strncat - Append a string to an existing string 356 * 357 * @p: pointer to NUL-terminated string to append to 358 * @q: pointer to source string to append from 359 * @count: Maximum bytes to read from @q 360 * 361 * Appends at most @count bytes from @q (stopping at the first 362 * NUL byte) after the NUL-terminated string at @p. @p will be 363 * NUL-terminated. 364 * 365 * Do not use this function. While FORTIFY_SOURCE tries to avoid 366 * read and write overflows, this is only possible when the sizes 367 * of @p and @q are known to the compiler. Prefer building the 368 * string with formatting, via scnprintf() or similar. 369 * 370 * Returns @p. 371 * 372 */ 373 /* Defined after fortified strlen() and strnlen() to reuse them. */ 374 __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3) 375 char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count) 376 { 377 size_t p_len, copy_len; 378 size_t p_size = __member_size(p); 379 size_t q_size = __member_size(q); 380 381 if (p_size == SIZE_MAX && q_size == SIZE_MAX) 382 return __underlying_strncat(p, q, count); 383 p_len = strlen(p); 384 copy_len = strnlen(q, count); 385 if (p_size < p_len + copy_len + 1) 386 fortify_panic(__func__); 387 __underlying_memcpy(p + p_len, q, copy_len); 388 p[p_len + copy_len] = '\0'; 389 return p; 390 } 391 392 __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, 393 const size_t p_size, 394 const size_t p_size_field) 395 { 396 if (__builtin_constant_p(size)) { 397 /* 398 * Length argument is a constant expression, so we 399 * can perform compile-time bounds checking where 400 * buffer sizes are also known at compile time. 401 */ 402 403 /* Error when size is larger than enclosing struct. */ 404 if (__compiletime_lessthan(p_size_field, p_size) && 405 __compiletime_lessthan(p_size, size)) 406 __write_overflow(); 407 408 /* Warn when write size is larger than dest field. */ 409 if (__compiletime_lessthan(p_size_field, size)) 410 __write_overflow_field(p_size_field, size); 411 } 412 /* 413 * At this point, length argument may not be a constant expression, 414 * so run-time bounds checking can be done where buffer sizes are 415 * known. (This is not an "else" because the above checks may only 416 * be compile-time warnings, and we want to still warn for run-time 417 * overflows.) 418 */ 419 420 /* 421 * Always stop accesses beyond the struct that contains the 422 * field, when the buffer's remaining size is known. 423 * (The SIZE_MAX test is to optimize away checks where the buffer 424 * lengths are unknown.) 425 */ 426 if (p_size != SIZE_MAX && p_size < size) 427 fortify_panic("memset"); 428 } 429 430 #define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({ \ 431 size_t __fortify_size = (size_t)(size); \ 432 fortify_memset_chk(__fortify_size, p_size, p_size_field), \ 433 __underlying_memset(p, c, __fortify_size); \ 434 }) 435 436 /* 437 * __struct_size() vs __member_size() must be captured here to avoid 438 * evaluating argument side-effects further into the macro layers. 439 */ 440 #ifndef CONFIG_KMSAN 441 #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ 442 __struct_size(p), __member_size(p)) 443 #endif 444 445 /* 446 * To make sure the compiler can enforce protection against buffer overflows, 447 * memcpy(), memmove(), and memset() must not be used beyond individual 448 * struct members. If you need to copy across multiple members, please use 449 * struct_group() to create a named mirror of an anonymous struct union. 450 * (e.g. see struct sk_buff.) Read overflow checking is currently only 451 * done when a write overflow is also present, or when building with W=1. 452 * 453 * Mitigation coverage matrix 454 * Bounds checking at: 455 * +-------+-------+-------+-------+ 456 * | Compile time | Run time | 457 * memcpy() argument sizes: | write | read | write | read | 458 * dest source length +-------+-------+-------+-------+ 459 * memcpy(known, known, constant) | y | y | n/a | n/a | 460 * memcpy(known, unknown, constant) | y | n | n/a | V | 461 * memcpy(known, known, dynamic) | n | n | B | B | 462 * memcpy(known, unknown, dynamic) | n | n | B | V | 463 * memcpy(unknown, known, constant) | n | y | V | n/a | 464 * memcpy(unknown, unknown, constant) | n | n | V | V | 465 * memcpy(unknown, known, dynamic) | n | n | V | B | 466 * memcpy(unknown, unknown, dynamic) | n | n | V | V | 467 * +-------+-------+-------+-------+ 468 * 469 * y = perform deterministic compile-time bounds checking 470 * n = cannot perform deterministic compile-time bounds checking 471 * n/a = no run-time bounds checking needed since compile-time deterministic 472 * B = can perform run-time bounds checking (currently unimplemented) 473 * V = vulnerable to run-time overflow (will need refactoring to solve) 474 * 475 */ 476 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, 477 const size_t p_size, 478 const size_t q_size, 479 const size_t p_size_field, 480 const size_t q_size_field, 481 const char *func) 482 { 483 if (__builtin_constant_p(size)) { 484 /* 485 * Length argument is a constant expression, so we 486 * can perform compile-time bounds checking where 487 * buffer sizes are also known at compile time. 488 */ 489 490 /* Error when size is larger than enclosing struct. */ 491 if (__compiletime_lessthan(p_size_field, p_size) && 492 __compiletime_lessthan(p_size, size)) 493 __write_overflow(); 494 if (__compiletime_lessthan(q_size_field, q_size) && 495 __compiletime_lessthan(q_size, size)) 496 __read_overflow2(); 497 498 /* Warn when write size argument larger than dest field. */ 499 if (__compiletime_lessthan(p_size_field, size)) 500 __write_overflow_field(p_size_field, size); 501 /* 502 * Warn for source field over-read when building with W=1 503 * or when an over-write happened, so both can be fixed at 504 * the same time. 505 */ 506 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || 507 __compiletime_lessthan(p_size_field, size)) && 508 __compiletime_lessthan(q_size_field, size)) 509 __read_overflow2_field(q_size_field, size); 510 } 511 /* 512 * At this point, length argument may not be a constant expression, 513 * so run-time bounds checking can be done where buffer sizes are 514 * known. (This is not an "else" because the above checks may only 515 * be compile-time warnings, and we want to still warn for run-time 516 * overflows.) 517 */ 518 519 /* 520 * Always stop accesses beyond the struct that contains the 521 * field, when the buffer's remaining size is known. 522 * (The SIZE_MAX test is to optimize away checks where the buffer 523 * lengths are unknown.) 524 */ 525 if ((p_size != SIZE_MAX && p_size < size) || 526 (q_size != SIZE_MAX && q_size < size)) 527 fortify_panic(func); 528 529 /* 530 * Warn when writing beyond destination field size. 531 * 532 * We must ignore p_size_field == 0 for existing 0-element 533 * fake flexible arrays, until they are all converted to 534 * proper flexible arrays. 535 * 536 * The implementation of __builtin_*object_size() behaves 537 * like sizeof() when not directly referencing a flexible 538 * array member, which means there will be many bounds checks 539 * that will appear at run-time, without a way for them to be 540 * detected at compile-time (as can be done when the destination 541 * is specifically the flexible array member). 542 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832 543 */ 544 if (p_size_field != 0 && p_size_field != SIZE_MAX && 545 p_size != p_size_field && p_size_field < size) 546 return true; 547 548 return false; 549 } 550 551 #define __fortify_memcpy_chk(p, q, size, p_size, q_size, \ 552 p_size_field, q_size_field, op) ({ \ 553 const size_t __fortify_size = (size_t)(size); \ 554 const size_t __p_size = (p_size); \ 555 const size_t __q_size = (q_size); \ 556 const size_t __p_size_field = (p_size_field); \ 557 const size_t __q_size_field = (q_size_field); \ 558 WARN_ONCE(fortify_memcpy_chk(__fortify_size, __p_size, \ 559 __q_size, __p_size_field, \ 560 __q_size_field, #op), \ 561 #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \ 562 __fortify_size, \ 563 "field \"" #p "\" at " __FILE__ ":" __stringify(__LINE__), \ 564 __p_size_field); \ 565 __underlying_##op(p, q, __fortify_size); \ 566 }) 567 568 /* 569 * Notes about compile-time buffer size detection: 570 * 571 * With these types... 572 * 573 * struct middle { 574 * u16 a; 575 * u8 middle_buf[16]; 576 * int b; 577 * }; 578 * struct end { 579 * u16 a; 580 * u8 end_buf[16]; 581 * }; 582 * struct flex { 583 * int a; 584 * u8 flex_buf[]; 585 * }; 586 * 587 * void func(TYPE *ptr) { ... } 588 * 589 * Cases where destination size cannot be currently detected: 590 * - the size of ptr's object (seemingly by design, gcc & clang fail): 591 * __builtin_object_size(ptr, 1) == SIZE_MAX 592 * - the size of flexible arrays in ptr's obj (by design, dynamic size): 593 * __builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX 594 * - the size of ANY array at the end of ptr's obj (gcc and clang bug): 595 * __builtin_object_size(ptr->end_buf, 1) == SIZE_MAX 596 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 597 * 598 * Cases where destination size is currently detected: 599 * - the size of non-array members within ptr's object: 600 * __builtin_object_size(ptr->a, 1) == 2 601 * - the size of non-flexible-array in the middle of ptr's obj: 602 * __builtin_object_size(ptr->middle_buf, 1) == 16 603 * 604 */ 605 606 /* 607 * __struct_size() vs __member_size() must be captured here to avoid 608 * evaluating argument side-effects further into the macro layers. 609 */ 610 #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ 611 __struct_size(p), __struct_size(q), \ 612 __member_size(p), __member_size(q), \ 613 memcpy) 614 #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ 615 __struct_size(p), __struct_size(q), \ 616 __member_size(p), __member_size(q), \ 617 memmove) 618 619 extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); 620 __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) 621 { 622 size_t p_size = __struct_size(p); 623 624 if (__compiletime_lessthan(p_size, size)) 625 __read_overflow(); 626 if (p_size < size) 627 fortify_panic(__func__); 628 return __real_memscan(p, c, size); 629 } 630 631 __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3) 632 int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size) 633 { 634 size_t p_size = __struct_size(p); 635 size_t q_size = __struct_size(q); 636 637 if (__builtin_constant_p(size)) { 638 if (__compiletime_lessthan(p_size, size)) 639 __read_overflow(); 640 if (__compiletime_lessthan(q_size, size)) 641 __read_overflow2(); 642 } 643 if (p_size < size || q_size < size) 644 fortify_panic(__func__); 645 return __underlying_memcmp(p, q, size); 646 } 647 648 __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) 649 void *memchr(const void * const POS0 p, int c, __kernel_size_t size) 650 { 651 size_t p_size = __struct_size(p); 652 653 if (__compiletime_lessthan(p_size, size)) 654 __read_overflow(); 655 if (p_size < size) 656 fortify_panic(__func__); 657 return __underlying_memchr(p, c, size); 658 } 659 660 void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); 661 __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) 662 { 663 size_t p_size = __struct_size(p); 664 665 if (__compiletime_lessthan(p_size, size)) 666 __read_overflow(); 667 if (p_size < size) 668 fortify_panic(__func__); 669 return __real_memchr_inv(p, c, size); 670 } 671 672 extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup) 673 __realloc_size(2); 674 __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) 675 { 676 size_t p_size = __struct_size(p); 677 678 if (__compiletime_lessthan(p_size, size)) 679 __read_overflow(); 680 if (p_size < size) 681 fortify_panic(__func__); 682 return __real_kmemdup(p, size, gfp); 683 } 684 685 /** 686 * strcpy - Copy a string into another string buffer 687 * 688 * @p: pointer to destination of copy 689 * @q: pointer to NUL-terminated source string to copy 690 * 691 * Do not use this function. While FORTIFY_SOURCE tries to avoid 692 * overflows, this is only possible when the sizes of @q and @p are 693 * known to the compiler. Prefer strscpy(), though note its different 694 * return values for detecting truncation. 695 * 696 * Returns @p. 697 * 698 */ 699 /* Defined after fortified strlen to reuse it. */ 700 __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2) 701 char *strcpy(char * const POS p, const char * const POS q) 702 { 703 size_t p_size = __member_size(p); 704 size_t q_size = __member_size(q); 705 size_t size; 706 707 /* If neither buffer size is known, immediately give up. */ 708 if (__builtin_constant_p(p_size) && 709 __builtin_constant_p(q_size) && 710 p_size == SIZE_MAX && q_size == SIZE_MAX) 711 return __underlying_strcpy(p, q); 712 size = strlen(q) + 1; 713 /* Compile-time check for const size overflow. */ 714 if (__compiletime_lessthan(p_size, size)) 715 __write_overflow(); 716 /* Run-time check for dynamic size overflow. */ 717 if (p_size < size) 718 fortify_panic(__func__); 719 __underlying_memcpy(p, q, size); 720 return p; 721 } 722 723 /* Don't use these outside the FORITFY_SOURCE implementation */ 724 #undef __underlying_memchr 725 #undef __underlying_memcmp 726 #undef __underlying_strcat 727 #undef __underlying_strcpy 728 #undef __underlying_strlen 729 #undef __underlying_strncat 730 #undef __underlying_strncpy 731 732 #undef POS 733 #undef POS0 734 735 #endif /* _LINUX_FORTIFY_STRING_H_ */ 736