checkmem.h (4302B)
1 /*********************************************************************** 2 * Copyright (c) 2022 Pieter Wuille * 3 * Distributed under the MIT software license, see the accompanying * 4 * file COPYING or https://www.opensource.org/licenses/mit-license.php.* 5 ***********************************************************************/ 6 7 /* The code here is inspired by Kris Kwiatkowski's approach in 8 * https://github.com/kriskwiatkowski/pqc/blob/main/src/common/ct_check.h 9 * to provide a general interface for memory-checking mechanisms, primarily 10 * for constant-time checking. 11 */ 12 13 /* These macros are defined by this header file: 14 * 15 * - SECP256K1_CHECKMEM_ENABLED: 16 * - 1 if memory-checking integration is available, 0 otherwise. 17 * This is just a compile-time macro. Use the next macro to check it is actually 18 * available at runtime. 19 * - SECP256K1_CHECKMEM_RUNNING(): 20 * - Acts like a function call, returning 1 if memory checking is available 21 * at runtime. 22 * - SECP256K1_CHECKMEM_CHECK(p, len): 23 * - Assert or otherwise fail in case the len-byte memory block pointed to by p is 24 * not considered entirely defined. 25 * - SECP256K1_CHECKMEM_CHECK_VERIFY(p, len): 26 * - Like SECP256K1_CHECKMEM_CHECK, but only works in VERIFY mode. 27 * - SECP256K1_CHECKMEM_UNDEFINE(p, len): 28 * - marks the len-byte memory block pointed to by p as undefined data (secret data, 29 * in the context of constant-time checking). 30 * - SECP256K1_CHECKMEM_DEFINE(p, len): 31 * - marks the len-byte memory pointed to by p as defined data (public data, in the 32 * context of constant-time checking). 33 * 34 */ 35 36 #ifndef SECP256K1_CHECKMEM_H 37 #define SECP256K1_CHECKMEM_H 38 39 /* Define a statement-like macro that ignores the arguments. */ 40 #define SECP256K1_CHECKMEM_NOOP(p, len) do { (void)(p); (void)(len); } while(0) 41 42 /* If compiling under msan, map the SECP256K1_CHECKMEM_* functionality to msan. 43 * Choose this preferentially, even when VALGRIND is defined, as msan-compiled 44 * binaries can't be run under valgrind anyway. */ 45 #if defined(__has_feature) 46 # if __has_feature(memory_sanitizer) 47 # include <sanitizer/msan_interface.h> 48 # define SECP256K1_CHECKMEM_ENABLED 1 49 # define SECP256K1_CHECKMEM_UNDEFINE(p, len) __msan_allocated_memory((p), (len)) 50 # define SECP256K1_CHECKMEM_DEFINE(p, len) __msan_unpoison((p), (len)) 51 # define SECP256K1_CHECKMEM_CHECK(p, len) __msan_check_mem_is_initialized((p), (len)) 52 # define SECP256K1_CHECKMEM_RUNNING() (1) 53 # endif 54 #endif 55 56 /* If valgrind integration is desired (through the VALGRIND define), implement the 57 * SECP256K1_CHECKMEM_* macros using valgrind. */ 58 #if !defined SECP256K1_CHECKMEM_ENABLED 59 # if defined VALGRIND 60 # include <stddef.h> 61 # if defined(__clang__) && defined(__APPLE__) 62 # pragma clang diagnostic push 63 # pragma clang diagnostic ignored "-Wreserved-identifier" 64 # endif 65 # include <valgrind/memcheck.h> 66 # if defined(__clang__) && defined(__APPLE__) 67 # pragma clang diagnostic pop 68 # endif 69 # define SECP256K1_CHECKMEM_ENABLED 1 70 # define SECP256K1_CHECKMEM_UNDEFINE(p, len) VALGRIND_MAKE_MEM_UNDEFINED((p), (len)) 71 # define SECP256K1_CHECKMEM_DEFINE(p, len) VALGRIND_MAKE_MEM_DEFINED((p), (len)) 72 # define SECP256K1_CHECKMEM_CHECK(p, len) VALGRIND_CHECK_MEM_IS_DEFINED((p), (len)) 73 /* VALGRIND_MAKE_MEM_DEFINED returns 0 iff not running on memcheck. 74 * This is more precise than the RUNNING_ON_VALGRIND macro, which 75 * checks for valgrind in general instead of memcheck specifically. */ 76 # define SECP256K1_CHECKMEM_RUNNING() (VALGRIND_MAKE_MEM_DEFINED(NULL, 0) != 0) 77 # endif 78 #endif 79 80 /* As a fall-back, map these macros to dummy statements. */ 81 #if !defined SECP256K1_CHECKMEM_ENABLED 82 # define SECP256K1_CHECKMEM_ENABLED 0 83 # define SECP256K1_CHECKMEM_UNDEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) 84 # define SECP256K1_CHECKMEM_DEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) 85 # define SECP256K1_CHECKMEM_CHECK(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) 86 # define SECP256K1_CHECKMEM_RUNNING() (0) 87 #endif 88 89 #if defined VERIFY 90 #define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_CHECK((p), (len)) 91 #else 92 #define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) 93 #endif 94 95 #endif /* SECP256K1_CHECKMEM_H */