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 /*
24 * Undefine and restore __section and __data from compiler.h to prevent
25 * collision with arm_neon.h
26 */
27 #pragma push_macro("__section")
28 #pragma push_macro("__data")
29 #undef __section
30 #undef __data
31 #include <arm_neon.h>
32 #pragma pop_macro("__data")
33 #pragma pop_macro("__section")
34 #define MBEDTLS_HAVE_NEON_INTRINSICS
35 #elif defined(MBEDTLS_PLATFORM_IS_WINDOWS_ON_ARM64)
36 #include <arm64_neon.h>
37 #define MBEDTLS_HAVE_NEON_INTRINSICS
38 #endif
39
40 /** Helper to define a function as static except when building invasive tests.
41 *
42 * If a function is only used inside its own source file and should be
43 * declared `static` to allow the compiler to optimize for code size,
44 * but that function has unit tests, define it with
45 * ```
46 * MBEDTLS_STATIC_TESTABLE int mbedtls_foo(...) { ... }
47 * ```
48 * and declare it in a header in the `library/` directory with
49 * ```
50 * #if defined(MBEDTLS_TEST_HOOKS)
51 * int mbedtls_foo(...);
52 * #endif
53 * ```
54 */
55 #if defined(MBEDTLS_TEST_HOOKS)
56 #define MBEDTLS_STATIC_TESTABLE
57 #else
58 #define MBEDTLS_STATIC_TESTABLE static
59 #endif
60
61 #if defined(MBEDTLS_TEST_HOOKS)
62 extern void (*mbedtls_test_hook_test_fail)(const char *test, int line, const char *file);
63 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) \
64 do { \
65 if ((!(TEST)) && ((*mbedtls_test_hook_test_fail) != NULL)) \
66 { \
67 (*mbedtls_test_hook_test_fail)( #TEST, __LINE__, __FILE__); \
68 } \
69 } while (0)
70 #else
71 #define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST)
72 #endif /* defined(MBEDTLS_TEST_HOOKS) */
73
74 /** \def ARRAY_LENGTH
75 * Return the number of elements of a static or stack array.
76 *
77 * \param array A value of array (not pointer) type.
78 *
79 * \return The number of elements of the array.
80 */
81 /* A correct implementation of ARRAY_LENGTH, but which silently gives
82 * a nonsensical result if called with a pointer rather than an array. */
83 #define ARRAY_LENGTH_UNSAFE(array) \
84 (sizeof(array) / sizeof(*(array)))
85
86 #if defined(__GNUC__)
87 /* Test if arg and &(arg)[0] have the same type. This is true if arg is
88 * an array but not if it's a pointer. */
89 #define IS_ARRAY_NOT_POINTER(arg) \
90 (!__builtin_types_compatible_p(__typeof__(arg), \
91 __typeof__(&(arg)[0])))
92 /* A compile-time constant with the value 0. If `const_expr` is not a
93 * compile-time constant with a nonzero value, cause a compile-time error. */
94 #define STATIC_ASSERT_EXPR(const_expr) \
95 (0 && sizeof(struct { unsigned int STATIC_ASSERT : 1 - 2 * !(const_expr); }))
96
97 /* Return the scalar value `value` (possibly promoted). This is a compile-time
98 * constant if `value` is. `condition` must be a compile-time constant.
99 * If `condition` is false, arrange to cause a compile-time error. */
100 #define STATIC_ASSERT_THEN_RETURN(condition, value) \
101 (STATIC_ASSERT_EXPR(condition) ? 0 : (value))
102
103 #define ARRAY_LENGTH(array) \
104 (STATIC_ASSERT_THEN_RETURN(IS_ARRAY_NOT_POINTER(array), \
105 ARRAY_LENGTH_UNSAFE(array)))
106
107 #else
108 /* If we aren't sure the compiler supports our non-standard tricks,
109 * fall back to the unsafe implementation. */
110 #define ARRAY_LENGTH(array) ARRAY_LENGTH_UNSAFE(array)
111 #endif
112 /** Allow library to access its structs' private members.
113 *
114 * Although structs defined in header files are publicly available,
115 * their members are private and should not be accessed by the user.
116 */
117 #define MBEDTLS_ALLOW_PRIVATE_ACCESS
118
119 /**
120 * \brief Securely zeroize a buffer then free it.
121 *
122 * Similar to making consecutive calls to
123 * \c mbedtls_platform_zeroize() and \c mbedtls_free(), but has
124 * code size savings, and potential for optimisation in the future.
125 *
126 * Guaranteed to be a no-op if \p buf is \c NULL and \p len is 0.
127 *
128 * \param buf Buffer to be zeroized then freed.
129 * \param len Length of the buffer in bytes
130 */
131 void mbedtls_zeroize_and_free(void *buf, size_t len);
132
133 /** Return an offset into a buffer.
134 *
135 * This is just the addition of an offset to a pointer, except that this
136 * function also accepts an offset of 0 into a buffer whose pointer is null.
137 * (`p + n` has undefined behavior when `p` is null, even when `n == 0`.
138 * A null pointer is a valid buffer pointer when the size is 0, for example
139 * as the result of `malloc(0)` on some platforms.)
140 *
141 * \param p Pointer to a buffer of at least n bytes.
142 * This may be \p NULL if \p n is zero.
143 * \param n An offset in bytes.
144 * \return Pointer to offset \p n in the buffer \p p.
145 * Note that this is only a valid pointer if the size of the
146 * buffer is at least \p n + 1.
147 */
mbedtls_buffer_offset(unsigned char * p,size_t n)148 static inline unsigned char *mbedtls_buffer_offset(
149 unsigned char *p, size_t n)
150 {
151 return p == NULL ? NULL : p + n;
152 }
153
154 /** Return an offset into a read-only buffer.
155 *
156 * Similar to mbedtls_buffer_offset(), but for const pointers.
157 *
158 * \param p Pointer to a buffer of at least n bytes.
159 * This may be \p NULL if \p n is zero.
160 * \param n An offset in bytes.
161 * \return Pointer to offset \p n in the buffer \p p.
162 * Note that this is only a valid pointer if the size of the
163 * buffer is at least \p n + 1.
164 */
mbedtls_buffer_offset_const(const unsigned char * p,size_t n)165 static inline const unsigned char *mbedtls_buffer_offset_const(
166 const unsigned char *p, size_t n)
167 {
168 return p == NULL ? NULL : p + n;
169 }
170
171 /* Always inline mbedtls_xor() for similar reasons as mbedtls_xor_no_simd(). */
172 #if defined(__IAR_SYSTEMS_ICC__)
173 #pragma inline = forced
174 #elif defined(__GNUC__)
175 __attribute__((always_inline))
176 #endif
177 /**
178 * Perform a fast block XOR operation, such that
179 * r[i] = a[i] ^ b[i] where 0 <= i < n
180 *
181 * \param r Pointer to result (buffer of at least \p n bytes). \p r
182 * may be equal to either \p a or \p b, but behaviour when
183 * it overlaps in other ways is undefined.
184 * \param a Pointer to input (buffer of at least \p n bytes)
185 * \param b Pointer to input (buffer of at least \p n bytes)
186 * \param n Number of bytes to process.
187 *
188 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or
189 * mbedtls_xor_no_simd() (these are functionally equivalent).
190 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in
191 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar
192 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where
193 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster.
194 * For targets without SIMD support, they will behave the same.
195 */
mbedtls_xor(unsigned char * r,const unsigned char * a,const unsigned char * b,size_t n)196 static inline void mbedtls_xor(unsigned char *r,
197 const unsigned char *a,
198 const unsigned char *b,
199 size_t n)
200 {
201 size_t i = 0;
202 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
203 #if defined(MBEDTLS_HAVE_NEON_INTRINSICS) && \
204 (!(defined(MBEDTLS_COMPILER_IS_GCC) && MBEDTLS_GCC_VERSION < 70300))
205 /* Old GCC versions generate a warning here, so disable the NEON path for these compilers */
206 for (; (i + 16) <= n; i += 16) {
207 uint8x16_t v1 = vld1q_u8(a + i);
208 uint8x16_t v2 = vld1q_u8(b + i);
209 uint8x16_t x = veorq_u8(v1, v2);
210 vst1q_u8(r + i, x);
211 }
212 #if defined(__IAR_SYSTEMS_ICC__) || defined(MBEDTLS_COMPILER_IS_GCC)
213 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case
214 * where n is a constant multiple of 16.
215 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time
216 * constant, and is a very small perf regression if n is not a compile-time constant.
217 * GCC 14.2 outputs a warning "array subscript 48 is outside array bounds" if we don't return
218 * early. */
219 if (n % 16 == 0) {
220 return;
221 }
222 #endif
223 #elif defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
224 /* This codepath probably only makes sense on architectures with 64-bit registers */
225 for (; (i + 8) <= n; i += 8) {
226 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
227 mbedtls_put_unaligned_uint64(r + i, x);
228 }
229 #if defined(__IAR_SYSTEMS_ICC__)
230 if (n % 8 == 0) {
231 return;
232 }
233 #endif
234 #else
235 for (; (i + 4) <= n; i += 4) {
236 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
237 mbedtls_put_unaligned_uint32(r + i, x);
238 }
239 #if defined(__IAR_SYSTEMS_ICC__)
240 if (n % 4 == 0) {
241 return;
242 }
243 #endif
244 #endif
245 #endif
246 for (; i < n; i++) {
247 r[i] = a[i] ^ b[i];
248 }
249 }
250
251 /* Always inline mbedtls_xor_no_simd() as we see significant perf regressions when it does not get
252 * inlined (e.g., observed about 3x perf difference in gcm_mult_largetable with gcc 7 - 12) */
253 #if defined(__IAR_SYSTEMS_ICC__)
254 #pragma inline = forced
255 #elif defined(__GNUC__)
256 __attribute__((always_inline))
257 #endif
258 /**
259 * Perform a fast block XOR operation, such that
260 * r[i] = a[i] ^ b[i] where 0 <= i < n
261 *
262 * In some situations, this can perform better than mbedtls_xor() (e.g., it's about 5%
263 * better in AES-CBC).
264 *
265 * \param r Pointer to result (buffer of at least \p n bytes). \p r
266 * may be equal to either \p a or \p b, but behaviour when
267 * it overlaps in other ways is undefined.
268 * \param a Pointer to input (buffer of at least \p n bytes)
269 * \param b Pointer to input (buffer of at least \p n bytes)
270 * \param n Number of bytes to process.
271 *
272 * \note Depending on the situation, it may be faster to use either mbedtls_xor() or
273 * mbedtls_xor_no_simd() (these are functionally equivalent).
274 * If the result is used immediately after the xor operation in non-SIMD code (e.g, in
275 * AES-CBC), there may be additional latency to transfer the data from SIMD to scalar
276 * registers, and in this case, mbedtls_xor_no_simd() may be faster. In other cases where
277 * the result is not used immediately (e.g., in AES-CTR), mbedtls_xor() may be faster.
278 * For targets without SIMD support, they will behave the same.
279 */
mbedtls_xor_no_simd(unsigned char * r,const unsigned char * a,const unsigned char * b,size_t n)280 static inline void mbedtls_xor_no_simd(unsigned char *r,
281 const unsigned char *a,
282 const unsigned char *b,
283 size_t n)
284 {
285 size_t i = 0;
286 #if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
287 #if defined(MBEDTLS_ARCH_IS_X64) || defined(MBEDTLS_ARCH_IS_ARM64)
288 /* This codepath probably only makes sense on architectures with 64-bit registers */
289 for (; (i + 8) <= n; i += 8) {
290 uint64_t x = mbedtls_get_unaligned_uint64(a + i) ^ mbedtls_get_unaligned_uint64(b + i);
291 mbedtls_put_unaligned_uint64(r + i, x);
292 }
293 #if defined(__IAR_SYSTEMS_ICC__)
294 /* This if statement helps some compilers (e.g., IAR) optimise out the byte-by-byte tail case
295 * where n is a constant multiple of 8.
296 * For other compilers (e.g. recent gcc and clang) it makes no difference if n is a compile-time
297 * constant, and is a very small perf regression if n is not a compile-time constant. */
298 if (n % 8 == 0) {
299 return;
300 }
301 #endif
302 #else
303 for (; (i + 4) <= n; i += 4) {
304 uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
305 mbedtls_put_unaligned_uint32(r + i, x);
306 }
307 #if defined(__IAR_SYSTEMS_ICC__)
308 if (n % 4 == 0) {
309 return;
310 }
311 #endif
312 #endif
313 #endif
314 for (; i < n; i++) {
315 r[i] = a[i] ^ b[i];
316 }
317 }
318
319 /* Fix MSVC C99 compatible issue
320 * MSVC support __func__ from visual studio 2015( 1900 )
321 * Use MSVC predefine macro to avoid name check fail.
322 */
323 #if (defined(_MSC_VER) && (_MSC_VER <= 1900))
324 #define /*no-check-names*/ __func__ __FUNCTION__
325 #endif
326
327 /* Define `asm` for compilers which don't define it. */
328 /* *INDENT-OFF* */
329 #ifndef asm
330 #if defined(__IAR_SYSTEMS_ICC__)
331 #define asm __asm
332 #else
333 #define asm __asm__
334 #endif
335 #endif
336 /* *INDENT-ON* */
337
338 /*
339 * Define the constraint used for read-only pointer operands to aarch64 asm.
340 *
341 * This is normally the usual "r", but for aarch64_32 (aka ILP32,
342 * as found in watchos), "p" is required to avoid warnings from clang.
343 *
344 * Note that clang does not recognise '+p' or '=p', and armclang
345 * does not recognise 'p' at all. Therefore, to update a pointer from
346 * aarch64 assembly, it is necessary to use something like:
347 *
348 * uintptr_t uptr = (uintptr_t) ptr;
349 * asm( "ldr x4, [%x0], #8" ... : "+r" (uptr) : : )
350 * ptr = (void*) uptr;
351 *
352 * Note that the "x" in "%x0" is neccessary; writing "%0" will cause warnings.
353 */
354 #if defined(__aarch64__) && defined(MBEDTLS_HAVE_ASM)
355 #if UINTPTR_MAX == 0xfffffffful
356 /* ILP32: Specify the pointer operand slightly differently, as per #7787. */
357 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "p"
358 #elif UINTPTR_MAX == 0xfffffffffffffffful
359 /* Normal case (64-bit pointers): use "r" as the constraint for pointer operands to asm */
360 #define MBEDTLS_ASM_AARCH64_PTR_CONSTRAINT "r"
361 #else
362 #error "Unrecognised pointer size for aarch64"
363 #endif
364 #endif
365
366 /* Always provide a static assert macro, so it can be used unconditionally.
367 * It does nothing on systems where we don't know how to define a static assert.
368 */
369 /* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it
370 * defines static_assert even with -std=c99, but then complains about it.
371 */
372 #if defined(static_assert) && !defined(__FreeBSD__)
373 #define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
374 #else
375 /* Make sure `MBEDTLS_STATIC_ASSERT(expr, msg);` is valid both inside and
376 * outside a function. We choose a struct declaration, which can be repeated
377 * any number of times and does not need a matching definition. */
378 #define MBEDTLS_STATIC_ASSERT(expr, msg) \
379 struct ISO_C_does_not_allow_extra_semicolon_outside_of_a_function
380 #endif
381
382 #if defined(__has_builtin)
383 #define MBEDTLS_HAS_BUILTIN(x) __has_builtin(x)
384 #else
385 #define MBEDTLS_HAS_BUILTIN(x) 0
386 #endif
387
388 /* Define compiler branch hints */
389 #if MBEDTLS_HAS_BUILTIN(__builtin_expect)
390 #define MBEDTLS_LIKELY(x) __builtin_expect(!!(x), 1)
391 #define MBEDTLS_UNLIKELY(x) __builtin_expect(!!(x), 0)
392 #else
393 #define MBEDTLS_LIKELY(x) x
394 #define MBEDTLS_UNLIKELY(x) x
395 #endif
396
397 /* MBEDTLS_ASSUME may be used to provide additional information to the compiler
398 * which can result in smaller code-size. */
399 #if MBEDTLS_HAS_BUILTIN(__builtin_assume)
400 /* clang provides __builtin_assume */
401 #define MBEDTLS_ASSUME(x) __builtin_assume(x)
402 #elif MBEDTLS_HAS_BUILTIN(__builtin_unreachable)
403 /* gcc and IAR can use __builtin_unreachable */
404 #define MBEDTLS_ASSUME(x) do { if (!(x)) __builtin_unreachable(); } while (0)
405 #elif defined(_MSC_VER)
406 /* Supported by MSVC since VS 2005 */
407 #define MBEDTLS_ASSUME(x) __assume(x)
408 #else
409 #define MBEDTLS_ASSUME(x) do { } while (0)
410 #endif
411
412 /* For gcc -Os, override with -O2 for a given function.
413 *
414 * This will not affect behaviour for other optimisation settings, e.g. -O0.
415 */
416 #if defined(MBEDTLS_COMPILER_IS_GCC) && defined(__OPTIMIZE_SIZE__)
417 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE __attribute__((optimize("-O2")))
418 #else
419 #define MBEDTLS_OPTIMIZE_FOR_PERFORMANCE
420 #endif
421
422 /* Suppress compiler warnings for unused functions and variables. */
423 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__has_attribute)
424 # if __has_attribute(unused)
425 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused))
426 # endif
427 #endif
428 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__GNUC__)
429 # define MBEDTLS_MAYBE_UNUSED __attribute__((unused))
430 #endif
431 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(__IAR_SYSTEMS_ICC__) && defined(__VER__)
432 /* IAR does support __attribute__((unused)), but only if the -e flag (extended language support)
433 * is given; the pragma always works.
434 * Unfortunately the pragma affects the rest of the file where it is used, but this is harmless.
435 * Check for version 5.2 or later - this pragma may be supported by earlier versions, but I wasn't
436 * able to find documentation).
437 */
438 # if (__VER__ >= 5020000)
439 # define MBEDTLS_MAYBE_UNUSED _Pragma("diag_suppress=Pe177")
440 # endif
441 #endif
442 #if !defined(MBEDTLS_MAYBE_UNUSED) && defined(_MSC_VER)
443 # define MBEDTLS_MAYBE_UNUSED __pragma(warning(suppress:4189))
444 #endif
445 #if !defined(MBEDTLS_MAYBE_UNUSED)
446 # define MBEDTLS_MAYBE_UNUSED
447 #endif
448
449 /* GCC >= 15 has a warning 'unterminated-string-initialization' which complains if you initialize
450 * a string into an array without space for a terminating NULL character. In some places in the
451 * codebase this behaviour is intended, so we add the macro MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
452 * to suppress the warning in these places.
453 */
454 #if defined(__has_attribute)
455 #if __has_attribute(nonstring)
456 #define MBEDTLS_HAS_ATTRIBUTE_NONSTRING
457 #endif /* __has_attribute(nonstring) */
458 #endif /* __has_attribute */
459 #if defined(MBEDTLS_HAS_ATTRIBUTE_NONSTRING)
460 #define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING __attribute__((nonstring))
461 #else
462 #define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
463 #endif /* MBEDTLS_HAS_ATTRIBUTE_NONSTRING */
464
465 #endif /* MBEDTLS_LIBRARY_COMMON_H */
466