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- /* vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80: */
- /*
- * Copyright (c) 2015 Red Hat, Inc.
- * Author: Nathaniel McCallum <npmccallum@redhat.com>
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *
- * Additional permission under GPLv3 section 7:
- *
- * In the following paragraph, "GPL" means the GNU General Public
- * License, version 3 or any later version, and "Non-GPL Code" means
- * code that is governed neither by the GPL nor a license
- * compatible with the GPL.
- *
- * You may link the code of this Program with Non-GPL Code and convey
- * linked combinations including the two, provided that such Non-GPL
- * Code only links to the code of this Program through those well
- * defined interfaces identified in the file named EXCEPTION found in
- * the source code files (the "Approved Interfaces"). The files of
- * Non-GPL Code may instantiate templates or use macros or inline
- * functions from the Approved Interfaces without causing the resulting
- * work to be covered by the GPL. Only the copyright holders of this
- * Program may make changes or additions to the list of Approved
- * Interfaces.
- */
- #define _GNU_SOURCE
- #include "sss.h"
- #include <jose/b64.h>
- #include <openssl/bn.h>
- #include <stdbool.h>
- #include <stddef.h>
- #include <stdint.h>
- #include <string.h>
- #include <sys/types.h>
- #include <sys/wait.h>
- #include <fcntl.h>
- #include <unistd.h>
- #include <signal.h>
- #define BIGNUM_auto __attribute__((cleanup(BN_cleanup))) BIGNUM
- #define BN_CTX_auto __attribute__((cleanup(BN_CTX_cleanup))) BN_CTX
- static BIGNUM *
- bn_decode(const uint8_t buf[], size_t len)
- {
- return BN_bin2bn(buf, len, NULL);
- }
- static BIGNUM *
- bn_decode_json(const json_t *json)
- {
- uint8_t *buf = NULL;
- BIGNUM *bn = NULL;
- size_t len;
- len = jose_b64_dec(json, NULL, 0);
- if (len == SIZE_MAX)
- return NULL;
- buf = malloc(len);
- if (!buf)
- return NULL;
- if (jose_b64_dec(json, buf, len) != len) {
- free(buf);
- return NULL;
- }
- bn = bn_decode(buf, len);
- free(buf);
- return bn;
- }
- static bool
- bn_encode(const BIGNUM *bn, uint8_t buf[], size_t len)
- {
- int bytes = 0;
- if (!bn)
- return false;
- if (len == 0)
- len = BN_num_bytes(bn);
- bytes = BN_num_bytes(bn);
- if (bytes < 0 || bytes > (int) len)
- return false;
- memset(buf, 0, len);
- return BN_bn2bin(bn, &buf[len - bytes]) > 0;
- }
- static json_t *
- bn_encode_json(const BIGNUM *bn, size_t len)
- {
- uint8_t *buf = NULL;
- json_t *out = NULL;
- if (!bn)
- return NULL;
- if (len == 0)
- len = BN_num_bytes(bn);
- if ((int) len < BN_num_bytes(bn))
- return NULL;
- buf = malloc(len);
- if (!buf)
- return NULL;
- if (!bn_encode(bn, buf, len)) {
- free(buf);
- return NULL;
- }
- out = jose_b64_enc(buf, len);
- free(buf);
- return out;
- }
- static void
- BN_CTX_cleanup(BN_CTX **ctx)
- {
- if (ctx)
- BN_CTX_free(*ctx);
- }
- static void
- BN_cleanup(BIGNUM **bnp)
- {
- if (bnp)
- BN_clear_free(*bnp);
- }
- json_t *
- sss_generate(size_t key_bytes, size_t threshold)
- {
- BIGNUM_auto *p = NULL;
- BIGNUM_auto *e = NULL;
- json_t *sss = NULL;
- if (key_bytes == 0 || threshold < 1)
- return NULL;
- p = BN_new();
- e = BN_new();
- if (!p || !e)
- goto error;
- if (!BN_generate_prime_ex(p, key_bytes * 8, 1, NULL, NULL, NULL))
- goto error;
- sss = json_pack("{s:i,s:[],s:o}", "t", threshold, "e", "p",
- bn_encode_json(p, key_bytes));
- if (!sss)
- goto error;
- for (size_t i = 0; i < threshold; i++) {
- if (BN_rand_range(e, p) <= 0)
- goto error;
- if (json_array_append_new(json_object_get(sss, "e"),
- bn_encode_json(e, key_bytes)))
- goto error;
- }
- return sss;
- error:
- json_decref(sss);
- return NULL;
- }
- uint8_t *
- sss_point(const json_t *sss, size_t *len)
- {
- BN_CTX_auto *ctx = NULL;
- BIGNUM_auto *tmp = NULL;
- BIGNUM_auto *xx = NULL;
- BIGNUM_auto *yy = NULL;
- BIGNUM_auto *pp = NULL;
- uint8_t *key = NULL;
- json_t *e = NULL;
- json_t *p = NULL;
- json_int_t t = 0;
- if (json_unpack((json_t *) sss, "{s:I,s:o,s:o}",
- "t", &t, "p", &p, "e", &e) != 0)
- return NULL;
- ctx = BN_CTX_new();
- pp = bn_decode_json(p);
- xx = BN_new();
- yy = BN_new();
- tmp = BN_new();
- if (!ctx || !pp || !xx || !yy || !tmp)
- return NULL;
- if (BN_rand_range(xx, pp) <= 0)
- return NULL;
- if (BN_set_word(yy, 0) <= 0)
- return NULL;
- for (size_t i = 0; i < json_array_size(e); i++) {
- BIGNUM_auto *ee = NULL;
- ee = bn_decode_json(json_array_get(e, i));
- if (!ee)
- return NULL;
- if (BN_cmp(pp, ee) <= 0)
- return NULL;
- /* y += e[i] * x^i */
- if (BN_set_word(tmp, i) <= 0)
- return NULL;
- if (BN_mod_exp(tmp, xx, tmp, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_mul(tmp, ee, tmp, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_add(yy, yy, tmp, pp, ctx) <= 0)
- return NULL;
- }
- *len = jose_b64_dec(p, NULL, 0);
- if (*len == SIZE_MAX)
- return NULL;
- key = malloc(*len * 2);
- if (!key)
- return NULL;
- if (!bn_encode(xx, key, *len) || !bn_encode(yy, &key[*len], *len)) {
- memset(key, 0, *len * 2);
- free(key);
- return NULL;
- }
- *len *= 2;
- return key;
- }
- json_t *
- sss_recover(const json_t *p, size_t npnts, const uint8_t *pnts[])
- {
- BN_CTX_auto *ctx = BN_CTX_new();
- BIGNUM_auto *pp = bn_decode_json(p);
- BIGNUM_auto *acc = BN_new();
- BIGNUM_auto *tmp = BN_new();
- BIGNUM_auto *k = BN_new();
- size_t len = 0;
- if (!ctx || !pp || !acc || !tmp || !k)
- return NULL;
- if (BN_set_word(k, 0) <= 0)
- return NULL;
- len = jose_b64_dec(p, NULL, 0);
- if (len == SIZE_MAX)
- return NULL;
- for (size_t i = 0; i < npnts; i++) {
- BIGNUM_auto *xo = NULL; /* Outer X */
- BIGNUM_auto *yo = NULL; /* Outer Y */
- xo = bn_decode(pnts[i], len);
- yo = bn_decode(&pnts[i][len], len);
- if (!xo || !yo)
- return NULL;
- if (BN_one(acc) <= 0)
- return NULL;
- for (size_t j = 0; j < npnts; j++) {
- BIGNUM_auto *xi = NULL; /* Inner X */
- if (i == j)
- continue;
- xi = bn_decode(pnts[j], len);
- if (!xi)
- return NULL;
- /* acc *= (0 - xi) / (xo - xi) */
- if (BN_set_word(tmp, 0) <= 0)
- return NULL;
- if (BN_mod_sub(tmp, tmp, xi, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_mul(acc, acc, tmp, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_sub(tmp, xo, xi, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_inverse(tmp, tmp, pp, ctx) != tmp)
- return NULL;
- if (BN_mod_mul(acc, acc, tmp, pp, ctx) <= 0)
- return NULL;
- }
- /* k += acc * y[i] */
- if (BN_mod_mul(acc, acc, yo, pp, ctx) <= 0)
- return NULL;
- if (BN_mod_add(k, k, acc, pp, ctx) <= 0)
- return NULL;
- }
- return bn_encode_json(k, len);
- }
- enum {
- PIPE_RD = 0,
- PIPE_WR = 1
- };
- FILE *
- call(char *const argv[], const void *buf, size_t len, pid_t *pid)
- {
- int dump[2] = { -1, -1 };
- int load[2] = { -1, -1 };
- FILE *out = NULL;
- ssize_t wr = 0;
- *pid = 0;
- if (pipe2(dump, O_CLOEXEC) < 0)
- goto error;
- if (pipe2(load, O_CLOEXEC) < 0)
- goto error;
- *pid = fork();
- if (*pid < 0)
- goto error;
- if (*pid == 0) {
- if (dup2(dump[PIPE_RD], STDIN_FILENO) < 0 ||
- dup2(load[PIPE_WR], STDOUT_FILENO) < 0)
- exit(EXIT_FAILURE);
- execvp(argv[0], argv);
- exit(EXIT_FAILURE);
- }
- for (const uint8_t *tmp = buf; len > 0; tmp += wr, len -= wr) {
- wr = write(dump[PIPE_WR], tmp, len);
- if (wr < 0)
- goto error;
- }
- out = fdopen(load[PIPE_RD], "r");
- if (!out)
- goto error;
- close(dump[PIPE_RD]);
- close(dump[PIPE_WR]);
- close(load[PIPE_WR]);
- return out;
- error:
- close(dump[PIPE_RD]);
- close(dump[PIPE_WR]);
- close(load[PIPE_RD]);
- close(load[PIPE_WR]);
- if (*pid > 0) {
- kill(*pid, SIGTERM);
- waitpid(*pid, NULL, 0);
- *pid = 0;
- }
- return NULL;
- }
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