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author | wolfbeast <mcwerewolf@gmail.com> | 2018-02-06 11:46:26 +0100 |
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committer | wolfbeast <mcwerewolf@gmail.com> | 2018-02-06 11:46:26 +0100 |
commit | f017b749ea9f1586d2308504553d40bf4cc5439d (patch) | |
tree | c6033924a0de9be1ab140596e305898c651bf57e /security/nss/fuzz/mpi_helper.cc | |
parent | 7c728b3c7680662fc4e92b5d03697b8339560b08 (diff) | |
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Update NSS to 3.32.1-RTM
Diffstat (limited to 'security/nss/fuzz/mpi_helper.cc')
-rw-r--r-- | security/nss/fuzz/mpi_helper.cc | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/security/nss/fuzz/mpi_helper.cc b/security/nss/fuzz/mpi_helper.cc new file mode 100644 index 000000000..65cf4b9cd --- /dev/null +++ b/security/nss/fuzz/mpi_helper.cc @@ -0,0 +1,100 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* Helper functions for MPI fuzzing targets. */ + +#include "mpi_helper.h" +#include <cstdlib> +#include <random> + +char *to_char(const uint8_t *x) { + return reinterpret_cast<char *>(const_cast<unsigned char *>(x)); +} + +// Check that the two numbers are equal. +void check_equal(BIGNUM *b, mp_int *m, size_t max_size) { + char *bnBc = BN_bn2hex(b); + char mpiMc[max_size]; + mp_tohex(m, mpiMc); + std::string bnA(bnBc); + std::string mpiA(mpiMc); + OPENSSL_free(bnBc); + // We have to strip leading zeros from bignums, ignoring the sign. + if (bnA.at(0) != '-') { + bnA.erase(0, std::min(bnA.find_first_not_of('0'), bnA.size() - 1)); + } else if (bnA.at(1) == '0') { + bnA.erase(1, std::min(bnA.find_first_not_of('0', 1) - 1, bnA.size() - 1)); + } + + if (mpiA != bnA) { + std::cout << "openssl: " << std::hex << bnA << std::endl; + std::cout << "nss: " << std::hex << mpiA << std::endl; + } + + assert(mpiA == bnA); +} + +// Parse data into two numbers for MPI and OpenSSL Bignum. +void parse_input(const uint8_t *data, size_t size, BIGNUM *A, BIGNUM *B, + mp_int *a, mp_int *b) { + // Note that b might overlap a. + size_t len = (size_t)size / 2; + assert(mp_read_raw(a, to_char(data), len) == MP_OKAY); + assert(mp_read_raw(b, to_char(data) + len, len) == MP_OKAY); + // Force a positive sign. + // TODO: add tests for negatives. + MP_SIGN(a) = MP_ZPOS; + MP_SIGN(b) = MP_ZPOS; + + // Skip the first byte as it's interpreted as sign by NSS. + assert(BN_bin2bn(data + 1, len - 1, A) != nullptr); + assert(BN_bin2bn(data + len + 1, len - 1, B) != nullptr); + + check_equal(A, a, 2 * size + 1); + check_equal(B, b, 2 * size + 1); +} + +// Parse data into a number for MPI and OpenSSL Bignum. +void parse_input(const uint8_t *data, size_t size, BIGNUM *A, mp_int *a) { + assert(mp_read_raw(a, to_char(data), size) == MP_OKAY); + + // Force a positive sign. + // TODO: add tests for negatives. + MP_SIGN(a) = MP_ZPOS; + + // Skip the first byte as it's interpreted as sign by NSS. + assert(BN_bin2bn(data + 1, size - 1, A) != nullptr); + + check_equal(A, a, 4 * size + 1); +} + +// Take a chunk in the middle of data and use it as modulus. +std::tuple<BIGNUM *, mp_int> get_modulus(const uint8_t *data, size_t size, + BN_CTX *ctx) { + BIGNUM *r1 = BN_CTX_get(ctx); + mp_int r2; + assert(mp_init(&r2) == MP_OKAY); + + size_t len = static_cast<size_t>(size / 4); + if (len != 0) { + assert(mp_read_raw(&r2, to_char(data + len), len) == MP_OKAY); + MP_SIGN(&r2) = MP_ZPOS; + + assert(BN_bin2bn(data + len + 1, len - 1, r1) != nullptr); + check_equal(r1, &r2, 2 * len + 1); + } + + // If we happen to get 0 for the modulus, take a random number. + if (mp_cmp_z(&r2) == 0 || len == 0) { + mp_zero(&r2); + BN_zero(r1); + std::mt19937 rng(data[0]); + std::uniform_int_distribution<mp_digit> dist(1, MP_DIGIT_MAX); + mp_digit x = dist(rng); + mp_add_d(&r2, x, &r2); + BN_add_word(r1, x); + } + + return std::make_tuple(r1, r2); +} |