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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
- * Copyright (c) 2013, Google Inc.
- */
- #include <libfdt.h>
- #include <u-boot/fdt-libcrypto.h>
- int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
- BIGNUM *num, int num_bits)
- {
- int nwords = num_bits / 32;
- int size;
- uint32_t *buf, *ptr;
- BIGNUM *tmp, *big2, *big32, *big2_32;
- BN_CTX *ctx;
- int ret;
- tmp = BN_new();
- big2 = BN_new();
- big32 = BN_new();
- big2_32 = BN_new();
- /*
- * Note: This code assumes that all of the above succeed, or all fail.
- * In practice memory allocations generally do not fail (unless the
- * process is killed), so it does not seem worth handling each of these
- * as a separate case. Technicaly this could leak memory on failure,
- * but a) it won't happen in practice, and b) it doesn't matter as we
- * will immediately exit with a failure code.
- */
- if (!tmp || !big2 || !big32 || !big2_32) {
- fprintf(stderr, "Out of memory (bignum)\n");
- return -ENOMEM;
- }
- ctx = BN_CTX_new();
- if (!ctx) {
- fprintf(stderr, "Out of memory (bignum context)\n");
- return -ENOMEM;
- }
- BN_set_word(big2, 2L);
- BN_set_word(big32, 32L);
- BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
- size = nwords * sizeof(uint32_t);
- buf = malloc(size);
- if (!buf) {
- fprintf(stderr, "Out of memory (%d bytes)\n", size);
- return -ENOMEM;
- }
- /* Write out modulus as big endian array of integers */
- for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
- BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
- *ptr = cpu_to_fdt32(BN_get_word(tmp));
- BN_rshift(num, num, 32); /* N = N/B */
- }
- /*
- * We try signing with successively increasing size values, so this
- * might fail several times
- */
- ret = fdt_setprop(blob, noffset, prop_name, buf, size);
- free(buf);
- BN_free(tmp);
- BN_free(big2);
- BN_free(big32);
- BN_free(big2_32);
- return ret ? -FDT_ERR_NOSPACE : 0;
- }
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