common.h (17339B)
1 /** 2 * \file common.h 3 * 4 * \brief Utility macros for internal use in the library 5 */ 6 /* 7 * Copyright The Mbed TLS Contributors 8 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 9 */ 10 11 #ifndef MBEDTLS_LIBRARY_COMMON_H 12 #define MBEDTLS_LIBRARY_COMMON_H 13 14 #include "mbedtls/build_info.h" 15 #include "alignment.h" 16 17 #include <assert.h> 18 #include <stddef.h> 19 #include <stdint.h> 20 #include <stddef.h> 21 22 #if defined(__ARM_NEON) 23 #include <arm_neon.h> 24 #define MBEDTLS_HAVE_NEON_INTRINSICS 25 #elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64) 26 #include <arm64_neon.h> 27 #define MBEDTLS_HAVE_NEON_INTRINSICS 28 #endif 29 30 /** Helper to define a function as static except when building invasive tests. 31 * 32 * If a function is only used inside its own source file and should be 33 * declared `static` to allow the compiler to optimize for code size, 34 * but that function has unit tests, define it with 35 * ``` 36 * MBEDTLS_STATIC_TESTABLE int mbedtls_foo(...) { ... } 37 * ``` 38 * and declare it in a header in the `library/` directory with 39 * ``` 40 * #if defined(MBEDTLS_TEST_HOOKS) 41 * int mbedtls_foo(...); 42 * #endif 43 * ``` 44 */ 45 #if defined(MBEDTLS_TEST_HOOKS) 46 #define MBEDTLS_STATIC_TESTABLE 47 #else 48 #define MBEDTLS_STATIC_TESTABLE static 49 #endif 50 51 #if defined(MBEDTLS_TEST_HOOKS) 52 extern void (*mbedtls_test_hook_test_fail)(const char *test, int line, const char *file); 53 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) \ 54 do { \ 55 if ((!(TEST)) && ((*mbedtls_test_hook_test_fail) != NULL)) \ 56 { \ 57 (*mbedtls_test_hook_test_fail)( #TEST, __LINE__, __FILE__); \ 58 } \ 59 } while (0) 60 #else 61 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) 62 #endif /* defined(MBEDTLS_TEST_HOOKS) */ 63 64 /** \def ARRAY_LENGTH 65 * Return the number of elements of a static or stack array. 66 * 67 * \param array A value of array (not pointer) type. 68 * 69 * \return The number of elements of the array. 70 */ 71 /* A correct implementation of ARRAY_LENGTH, but which silently gives 72 * a nonsensical result if called with a pointer rather than an array. */ 73 #define ARRAY_LENGTH_UNSAFE(array) \ 74 (sizeof(array) / sizeof(*(array))) 75 76 #if defined(__GNUC__) 77 /* Test if arg and &(arg)[0] have the same type. This is true if arg is 78 * an array but not if it's a pointer. */ 79 #define IS_ARRAY_NOT_POINTER(arg) \ 80 (!__builtin_types_compatible_p(__typeof__(arg), \ 81 __typeof__(&(arg)[0]))) 82 /* A compile-time constant with the value 0. If `const_expr` is not a 83 * compile-time constant with a nonzero value, cause a compile-time error. */ 84 #define STATIC_ASSERT_EXPR(const_expr) \ 85 (0 && sizeof(struct { unsigned int STATIC_ASSERT : 1 - 2 * !(const_expr); })) 86 87 /* Return the scalar value `value` (possibly promoted). This is a compile-time 88 * constant if `value` is. `condition` must be a compile-time constant. 89 * If `condition` is false, arrange to cause a compile-time error. */ 90 #define STATIC_ASSERT_THEN_RETURN(condition, value) \ 91 (STATIC_ASSERT_EXPR(condition) ? 0 : (value)) 92 93 #define ARRAY_LENGTH(array) \ 94 (STATIC_ASSERT_THEN_RETURN(IS_ARRAY_NOT_POINTER(array), \ 95 ARRAY_LENGTH_UNSAFE(array))) 96 97 #else 98 /* If we aren't sure the compiler supports our non-standard tricks, 99 * fall back to the unsafe implementation. */ 100 #define ARRAY_LENGTH(array) ARRAY_LENGTH_UNSAFE(array) 101 #endif 102 /** Allow library to access its structs' private members. 103 * 104 * Although structs defined in header files are publicly available, 105 * their members are private and should not be accessed by the user. 106 */ 107 #define MBEDTLS_ALLOW_PRIVATE_ACCESS 108 109 /** 110 * \brief Securely zeroize a buffer then free it. 111 * 112 * Similar to making consecutive calls to 113 * \c mbedtls_platform_zeroize() and \c mbedtls_free(), but has 114 * code size savings, and potential for optimisation in the future. 115 * 116 * Guaranteed to be a no-op if \p buf is \c NULL and \p len is 0. 117 * 118 * \param buf Buffer to be zeroized then freed. 119 * \param len Length of the buffer in bytes 120 */ 121 void mbedtls_zeroize_and_free(void *buf, size_t len); 122 123 /** Return an offset into a buffer. 124 * 125 * This is just the addition of an offset to a pointer, except that this 126 * function also accepts an offset of 0 into a buffer whose pointer is null. 127 * (`p + n` has undefined behavior when `p` is null, even when `n == 0`. 128 * A null pointer is a valid buffer pointer when the size is 0, for example 129 * as the result of `malloc(0)` on some platforms.) 130 * 131 * \param p Pointer to a buffer of at least n bytes. 132 * This may be \p NULL if \p n is zero. 133 * \param n An offset in bytes. 134 * \return Pointer to offset \p n in the buffer \p p. 135 * Note that this is only a valid pointer if the size of the 136 * buffer is at least \p n + 1. 137 */ 138 static inline unsigned char *mbedtls_buffer_offset( 139 unsigned char *p, size_t n) 140 { 141 return p == NULL ? NULL : p + n; 142 } 143 144 /** Return an offset into a read-only buffer. 145 * 146 * Similar to mbedtls_buffer_offset(), but for const pointers. 147 * 148 * \param p Pointer to a buffer of at least n bytes. 149 * This may be \p NULL if \p n is zero. 150 * \param n An offset in bytes. 151 * \return Pointer to offset \p n in the buffer \p p. 152 * Note that this is only a valid pointer if the size of the 153 * buffer is at least \p n + 1. 154 */ 155 static inline const unsigned char *mbedtls_buffer_offset_const( 156 const unsigned char *p, size_t n) 157 { 158 return p == NULL ? NULL : p + n; 159 } 160 161 /* Always inline mbedtls_xor() for similar reasons as mbedtls_xor_no_simd(). */ 162 #if defined(__IAR_SYSTEMS_ICC__) 163 #pragma inline = forced 164 #elif defined(__GNUC__) 165 __attribute__((always_inline)) 166 #endif 167 /** 168 * Perform a fast block XOR operation, such that 169 * r[i] = a[i] ^ b[i] where 0 <= i < n 170 * 171 * \param r Pointer to result (buffer of at least \p n bytes). \p r 172 * may be equal to either \p a or \p b, but behaviour when 173 * it overlaps in other ways is undefined. 174 * \param a Pointer to input (buffer of at least \p n bytes) 175 * \param b Pointer to input (buffer of at least \p n bytes) 176 * \param n Number of bytes to process. 177 * 178 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or 179 * mbedtls_xor_no_simd() (these are functionally equivalent). 180 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in 181 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar 182 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where 183 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster. 184 * For targets without SIMD support, they will behave the same. 185 */ 186 static inline void mbedtls_xor(unsigned char *r, 187 const unsigned char *a, 188 const unsigned char *b, 189 size_t n) 190 { 191 size_t i = 0; 192 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS) 193 #if defined(MBEDTLS_HAVE_NEON_INTRINSICS) && \ 194 (!(defined(MBEDTLS_COMPILER_IS_GCC) && MBEDTLS_GCC_VERSION < 70300)) 195 /* Old GCC versions generate a warning here, so disable the NEON path for these compilers */ 196 for (; (i + 16) <= n; i += 16) { 197 uint8x16_t v1 = vld1q_u8(a + i); 198 uint8x16_t v2 = vld1q_u8(b + i); 199 uint8x16_t x = veorq_u8(v1, v2); 200 vst1q_u8(r + i, x); 201 } 202 #if defined(__IAR_SYSTEMS_ICC__) 203 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case 204 * where n is a constant multiple of 16. 205 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time 206 * constant, and is a very small perf regression if n is not a compile-time constant. */ 207 if (n % 16 == 0) { 208 return; 209 } 210 #endif 211 #elif defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64) 212 /* This codepath probably only makes sense on architectures with 64-bit registers */ 213 for (; (i + 8) <= n; i += 8) { 214 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i); 215 mbedtls_put_unaligned_uint64(r + i, x); 216 } 217 #if defined(__IAR_SYSTEMS_ICC__) 218 if (n % 8 == 0) { 219 return; 220 } 221 #endif 222 #else 223 for (; (i + 4) <= n; i += 4) { 224 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i); 225 mbedtls_put_unaligned_uint32(r + i, x); 226 } 227 #if defined(__IAR_SYSTEMS_ICC__) 228 if (n % 4 == 0) { 229 return; 230 } 231 #endif 232 #endif 233 #endif 234 for (; i < n; i++) { 235 r[i] = a[i] ^ b[i]; 236 } 237 } 238 239 /* Always inline mbedtls_xor_no_simd() as we see significant perf regressions when it does not get 240 * inlined (e.g., observed about 3x perf difference in gcm_mult_largetable with gcc 7 - 12) */ 241 #if defined(__IAR_SYSTEMS_ICC__) 242 #pragma inline = forced 243 #elif defined(__GNUC__) 244 __attribute__((always_inline)) 245 #endif 246 /** 247 * Perform a fast block XOR operation, such that 248 * r[i] = a[i] ^ b[i] where 0 <= i < n 249 * 250 * In some situations, this can perform better than mbedtls_xor() (e.g., it's about 5% 251 * better in AES-CBC). 252 * 253 * \param r Pointer to result (buffer of at least \p n bytes). \p r 254 * may be equal to either \p a or \p b, but behaviour when 255 * it overlaps in other ways is undefined. 256 * \param a Pointer to input (buffer of at least \p n bytes) 257 * \param b Pointer to input (buffer of at least \p n bytes) 258 * \param n Number of bytes to process. 259 * 260 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or 261 * mbedtls_xor_no_simd() (these are functionally equivalent). 262 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in 263 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar 264 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where 265 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster. 266 * For targets without SIMD support, they will behave the same. 267 */ 268 static inline void mbedtls_xor_no_simd(unsigned char *r, 269 const unsigned char *a, 270 const unsigned char *b, 271 size_t n) 272 { 273 size_t i = 0; 274 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS) 275 #if defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64) 276 /* This codepath probably only makes sense on architectures with 64-bit registers */ 277 for (; (i + 8) <= n; i += 8) { 278 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i); 279 mbedtls_put_unaligned_uint64(r + i, x); 280 } 281 #if defined(__IAR_SYSTEMS_ICC__) 282 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case 283 * where n is a constant multiple of 8. 284 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time 285 * constant, and is a very small perf regression if n is not a compile-time constant. */ 286 if (n % 8 == 0) { 287 return; 288 } 289 #endif 290 #else 291 for (; (i + 4) <= n; i += 4) { 292 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i); 293 mbedtls_put_unaligned_uint32(r + i, x); 294 } 295 #if defined(__IAR_SYSTEMS_ICC__) 296 if (n % 4 == 0) { 297 return; 298 } 299 #endif 300 #endif 301 #endif 302 for (; i < n; i++) { 303 r[i] = a[i] ^ b[i]; 304 } 305 } 306 307 /* Fix MSVC C99 compatible issue 308 * MSVC support __func__ from visual studio 2015( 1900 ) 309 * Use MSVC predefine macro to avoid name check fail. 310 */ 311 #if (defined(_MSC_VER) && (_MSC_VER <= 1900)) 312 #define /*no-check-names*/ __func__ __FUNCTION__ 313 #endif 314 315 /* Define `asm` for compilers which don't define it. */ 316 /* *INDENT-OFF* */ 317 #ifndef asm 318 #if defined(__IAR_SYSTEMS_ICC__) 319 #define asm __asm 320 #else 321 #define asm __asm__ 322 #endif 323 #endif 324 /* *INDENT-ON* */ 325 326 /* 327 * Define the constraint used for read-only pointer operands to aarch64 asm. 328 * 329 * This is normally the usual "r", but for aarch64_32 (aka ILP32, 330 * as found in watchos), "p" is required to avoid warnings from clang. 331 * 332 * Note that clang does not recognise '+p' or '=p', and armclang 333 * does not recognise 'p' at all. Therefore, to update a pointer from 334 * aarch64 assembly, it is necessary to use something like: 335 * 336 * uintptr_t uptr = (uintptr_t) ptr; 337 * asm( "ldr x4, [%x0], #8" ... : "+r" (uptr) : : ) 338 * ptr = (void*) uptr; 339 * 340 * Note that the "x" in "%x0" is neccessary; writing "%0" will cause warnings. 341 */ 342 #if defined(__aarch64__) && defined(MBEDTLS_HAVE_ASM) 343 #if UINTPTR_MAX == 0xfffffffful 344 /* ILP32: Specify the pointer operand slightly differently, as per #7787. */ 345 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "p" 346 #elif UINTPTR_MAX == 0xfffffffffffffffful 347 /* Normal case (64-bit pointers): use "r" as the constraint for pointer operands to asm */ 348 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "r" 349 #else 350 #error "Unrecognised pointer size for aarch64" 351 #endif 352 #endif 353 354 /* Always provide a static assert macro, so it can be used unconditionally. 355 * It does nothing on systems where we don't know how to define a static assert. 356 */ 357 /* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it 358 * defines static_assert even with -std=c99, but then complains about it. 359 */ 360 #if defined(static_assert) && !defined(__FreeBSD__) 361 #define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg) 362 #else 363 /* Make sure `MBEDTLS_STATIC_ASSERT(expr, msg);` is valid both inside and 364 * outside a function. We choose a struct declaration, which can be repeated 365 * any number of times and does not need a matching definition. */ 366 #define MBEDTLS_STATIC_ASSERT(expr, msg) \ 367 struct ISO_C_does_not_allow_extra_semicolon_outside_of_a_function 368 #endif 369 370 #if defined(__has_builtin) 371 #define MBEDTLS_HAS_BUILTIN(x) __has_builtin(x) 372 #else 373 #define MBEDTLS_HAS_BUILTIN(x) 0 374 #endif 375 376 /* Define compiler branch hints */ 377 #if MBEDTLS_HAS_BUILTIN(__builtin_expect) 378 #define MBEDTLS_LIKELY(x) __builtin_expect(!!(x), 1) 379 #define MBEDTLS_UNLIKELY(x) __builtin_expect(!!(x), 0) 380 #else 381 #define MBEDTLS_LIKELY(x) x 382 #define MBEDTLS_UNLIKELY(x) x 383 #endif 384 385 /* MBEDTLS_ASSUME may be used to provide additional information to the compiler 386 * which can result in smaller code-size. */ 387 #if MBEDTLS_HAS_BUILTIN(__builtin_assume) 388 /* clang provides __builtin_assume */ 389 #define MBEDTLS_ASSUME(x) __builtin_assume(x) 390 #elif MBEDTLS_HAS_BUILTIN(__builtin_unreachable) 391 /* gcc and IAR can use __builtin_unreachable */ 392 #define MBEDTLS_ASSUME(x) do { if (!(x)) __builtin_unreachable(); } while (0) 393 #elif defined(_MSC_VER) 394 /* Supported by MSVC since VS 2005 */ 395 #define MBEDTLS_ASSUME(x) __assume(x) 396 #else 397 #define MBEDTLS_ASSUME(x) do { } while (0) 398 #endif 399 400 /* For gcc -Os, override with -O2 for a given function. 401 * 402 * This will not affect behaviour for other optimisation settings, e.g. -O0. 403 */ 404 #if defined(MBEDTLS_COMPILER_IS_GCC) && defined(__OPTIMIZE_SIZE__) 405 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE __attribute__((optimize("-O2"))) 406 #else 407 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE 408 #endif 409 410 /* Suppress compiler warnings for unused functions and variables. */ 411 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__has_attribute) 412 # if __has_attribute(unused) 413 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused)) 414 # endif 415 #endif 416 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__GNUC__) 417 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused)) 418 #endif 419 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__IAR_SYSTEMS_ICC__) && defined(__VER__) 420 /* IAR does support __attribute__((unused)), but only if the -e flag (extended language support) 421 * is given; the pragma always works. 422 * Unfortunately the pragma affects the rest of the file where it is used, but this is harmless. 423 * Check for version 5.2 or later - this pragma may be supported by earlier versions, but I wasn't 424 * able to find documentation). 425 */ 426 # if (__VER__ >= 5020000) 427 # define MBEDTLS_MAYBE_UNUSED _Pragma("diag_suppress=Pe177") 428 # endif 429 #endif 430 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(_MSC_VER) 431 # define MBEDTLS_MAYBE_UNUSED __pragma(warning(suppress:4189)) 432 #endif 433 #if !defined(MBEDTLS_MAYBE_UNUSED) 434 # define MBEDTLS_MAYBE_UNUSED 435 #endif 436 437 /* GCC >= 15 has a warning 'unterminated-string-initialization' which complains if you initialize 438 * a string into an array without space for a terminating NULL character. In some places in the 439 * codebase this behaviour is intended, so we add the macro MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING 440 * to suppress the warning in these places. 441 */ 442 #if defined(__has_attribute) 443 #if __has_attribute(nonstring) 444 #define MBEDTLS_HAS_ATTRIBUTE_NONSTRING 445 #endif /* __has_attribute(nonstring) */ 446 #endif /* __has_attribute */ 447 #if defined(MBEDTLS_HAS_ATTRIBUTE_NONSTRING) 448 #define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING __attribute__((nonstring)) 449 #else 450 #define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING 451 #endif /* MBEDTLS_HAS_ATTRIBUTE_NONSTRING */ 452 453 #endif /* MBEDTLS_LIBRARY_COMMON_H */