[PATCH RFC v2 2/5] lib/rsa: Make fdt_add_bignum() available outside of RSA code

Alexandru Gagniuc
2020-12-30T21:00:24Z

fdt_add_bignum() is useful for algorithms other than just RSA. To
allow its use for ECDSA, move it to a common file under lib/.

The new file is suffixed with '-libcrypto' because it has a direct
dependency on openssl. This is due to the use of the "BIGNUM *" type.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
include/u-boot/fdt-libcrypto.h | 15 +++++++
lib/fdt-libcrypto.c | 72 ++++++++++++++++++++++++++++++++++
lib/rsa/rsa-sign.c | 65 +-----------------------------
tools/Makefile | 1 +
4 files changed, 89 insertions(+), 64 deletions(-)
create mode 100644 include/u-boot/fdt-libcrypto.h
create mode 100644 lib/fdt-libcrypto.c

diff --git a/include/u-boot/fdt-libcrypto.h b/include/u-boot/fdt-libcrypto.h
new file mode 100644
index 0000000000..a6873487ed
--- /dev/null
+++ b/include/u-boot/fdt-libcrypto.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ * Copyright (c) 2013, Google Inc.
+ */
+
+#ifndef _FDT_LIBCRYPTO_H
+#define _FDT_LIBCRYPTO_H
+
+#include <openssl/bn.h>
+
+int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
+ BIGNUM *num, int num_bits);
+
+#endif /* _FDT_LIBCRYPTO_H */
diff --git a/lib/fdt-libcrypto.c b/lib/fdt-libcrypto.c
new file mode 100644
index 0000000000..ecb0344c8f
--- /dev/null
+++ b/lib/fdt-libcrypto.c
@@ -0,0 +1,72 @@
+// 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;
+}
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 1f0d81bd7a..557c690a6d 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -9,6 +9,7 @@
#include <string.h>
#include <image.h>
#include <time.h>
+#include <u-boot/fdt-libcrypto.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
@@ -680,70 +681,6 @@ int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
return ret;
}

-static 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;
-}
-
int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
{
BIGNUM *modulus, *r_squared;
diff --git a/tools/Makefile b/tools/Makefile
index b1595ad814..af7698fd01 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -106,6 +106,7 @@ dumpimage-mkimage-objs := aisimage.o \
socfpgaimage.o \
lib/crc16.o \
lib/hash-checksum.o \
+ lib/fdt-libcrypto.o \
lib/sha1.o \
lib/sha256.o \
lib/sha512.o \
--
2.26.2