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