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Diffstat (limited to 'src/checkmem.h')
| -rw-r--r-- | src/checkmem.h | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/src/checkmem.h b/src/checkmem.h new file mode 100644 index 0000000000..571e4cc389 --- /dev/null +++ b/src/checkmem.h @@ -0,0 +1,88 @@ +/*********************************************************************** + * Copyright (c) 2022 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +/* The code here is inspired by Kris Kwiatkowski's approach in + * https://github.com/kriskwiatkowski/pqc/blob/main/src/common/ct_check.h + * to provide a general interface for memory-checking mechanisms, primarily + * for constant-time checking. + */ + +/* These macros are defined by this header file: + * + * - SECP256K1_CHECKMEM_ENABLED: + * - 1 if memory-checking integration is available, 0 otherwise. + * This is just a compile-time macro. Use the next macro to check it is actually + * available at runtime. + * - SECP256K1_CHECKMEM_RUNNING(): + * - Acts like a function call, returning 1 if memory checking is available + * at runtime. + * - SECP256K1_CHECKMEM_CHECK(p, len): + * - Assert or otherwise fail in case the len-byte memory block pointed to by p is + * not considered entirely defined. + * - SECP256K1_CHECKMEM_CHECK_VERIFY(p, len): + * - Like SECP256K1_CHECKMEM_CHECK, but only works in VERIFY mode. + * - SECP256K1_CHECKMEM_UNDEFINE(p, len): + * - marks the len-byte memory block pointed to by p as undefined data (secret data, + * in the context of constant-time checking). + * - SECP256K1_CHECKMEM_DEFINE(p, len): + * - marks the len-byte memory pointed to by p as defined data (public data, in the + * context of constant-time checking). + * + */ + +#ifndef SECP256K1_CHECKMEM_H +#define SECP256K1_CHECKMEM_H + +/* Define a statement-like macro that ignores the arguments. */ +#define SECP256K1_CHECKMEM_NOOP(p, len) do { (void)(p); (void)(len); } while(0) + +/* If compiling under msan, map the SECP256K1_CHECKMEM_* functionality to msan. + * Choose this preferentially, even when VALGRIND is defined, as msan-compiled + * binaries can't be run under valgrind anyway. */ +#if defined(__has_feature) +# if __has_feature(memory_sanitizer) +# include <sanitizer/msan_interface.h> +# define SECP256K1_CHECKMEM_ENABLED 1 +# define SECP256K1_CHECKMEM_UNDEFINE(p, len) __msan_allocated_memory((p), (len)) +# define SECP256K1_CHECKMEM_DEFINE(p, len) __msan_unpoison((p), (len)) +# define SECP256K1_CHECKMEM_CHECK(p, len) __msan_check_mem_is_initialized((p), (len)) +# define SECP256K1_CHECKMEM_RUNNING() (1) +# endif +#endif + +/* If valgrind integration is desired (through the VALGRIND define), implement the + * SECP256K1_CHECKMEM_* macros using valgrind. */ +#if !defined SECP256K1_CHECKMEM_ENABLED +# if defined VALGRIND +# include <stddef.h> +# include <valgrind/memcheck.h> +# define SECP256K1_CHECKMEM_ENABLED 1 +# define SECP256K1_CHECKMEM_UNDEFINE(p, len) VALGRIND_MAKE_MEM_UNDEFINED((p), (len)) +# define SECP256K1_CHECKMEM_DEFINE(p, len) VALGRIND_MAKE_MEM_DEFINED((p), (len)) +# define SECP256K1_CHECKMEM_CHECK(p, len) VALGRIND_CHECK_MEM_IS_DEFINED((p), (len)) + /* VALGRIND_MAKE_MEM_DEFINED returns 0 iff not running on memcheck. + * This is more precise than the RUNNING_ON_VALGRIND macro, which + * checks for valgrind in general instead of memcheck specifically. */ +# define SECP256K1_CHECKMEM_RUNNING() (VALGRIND_MAKE_MEM_DEFINED(NULL, 0) != 0) +# endif +#endif + +/* As a fall-back, map these macros to dummy statements. */ +#if !defined SECP256K1_CHECKMEM_ENABLED +# define SECP256K1_CHECKMEM_ENABLED 0 +# define SECP256K1_CHECKMEM_UNDEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) +# define SECP256K1_CHECKMEM_DEFINE(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) +# define SECP256K1_CHECKMEM_CHECK(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) +# define SECP256K1_CHECKMEM_RUNNING() (0) +#endif + +#if defined VERIFY +#define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_CHECK((p), (len)) +#else +#define SECP256K1_CHECKMEM_CHECK_VERIFY(p, len) SECP256K1_CHECKMEM_NOOP((p), (len)) +#endif + +#endif /* SECP256K1_CHECKMEM_H */ |