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