mkfs.ubifs: Add crypto helper functions

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 327 insertions, 0 deletions

diff --git a/ubifs-utils/mkfs.ubifs/crypto.c b/ubifs-utils/mkfs.ubifs/crypto.c
new file mode 100644
index 0000000..a20bd56
--- /dev/null
+++ b/ubifs-utils/mkfs.ubifs/crypto.c
@@ -0,0 +1,327 @@
+/*
+ * Copyright (C) 2017 sigma star gmbh
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * 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, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
+ */
+
+#define PROGRAM_NAME "mkfs.ubifs"
+#include <openssl/evp.h>
+#include <openssl/err.h>
+#include <string.h>
+#include <assert.h>
+
+#include "crypto.h"
+#include "common.h"
+#include "mtd_swab.h"
+
+
+static struct cipher ciphers[] = {
+	{
+		.name = "AES-128-CBC",
+		.encrypt_block = encrypt_block_aes128_cbc,
+		.encrypt_fname = encrypt_aes128_cbc_cts,
+	}, {
+		.name = "AES-256-XTS",
+		.encrypt_block = encrypt_block_aes256_xts,
+		.encrypt_fname = encrypt_aes256_cbc_cts,
+	}
+};
+
+
+
+static int do_sha256(const unsigned char *in, size_t len, unsigned char *out)
+{
+	unsigned int out_len;
+	EVP_MD_CTX *mdctx = EVP_MD_CTX_create();
+
+	if (!mdctx)
+		return -1;
+
+	if (EVP_DigestInit_ex(mdctx, EVP_sha256(), NULL) != 1)
+		return -1;
+
+	if(EVP_DigestUpdate(mdctx, in, len) != 1)
+		return -1;
+
+	if(EVP_DigestFinal_ex(mdctx, out, &out_len) != 1)
+		return -1;
+
+	EVP_MD_CTX_destroy(mdctx);
+
+	return 0;
+}
+
+static int check_iv_key_size(const EVP_CIPHER *cipher, size_t key_len,
+				size_t iv_len)
+{
+	if ((size_t)EVP_CIPHER_key_length(cipher) != key_len) {
+		errmsg("Cipher key length mismatch. Expected %lu, got %d",
+			(unsigned long)key_len, EVP_CIPHER_key_length(cipher));
+		return -1;
+	}
+
+	if (iv_len && (size_t)EVP_CIPHER_iv_length(cipher) != iv_len) {
+		errmsg("Cipher IV length mismatch. Expected %lu, got %d",
+			(unsigned long)iv_len, EVP_CIPHER_key_length(cipher));
+		return -1;
+	}
+
+	return 0;
+}
+
+static ssize_t do_encrypt(const EVP_CIPHER *cipher,
+				const void *plaintext, size_t size,
+				const void *key, size_t key_len,
+				const void *iv, size_t iv_len,
+				void *ciphertext)
+{
+	int ciphertext_len, len;
+	EVP_CIPHER_CTX *ctx;
+
+	if (check_iv_key_size(cipher, key_len, iv_len))
+		return -1;
+
+	if (!(ctx = EVP_CIPHER_CTX_new()))
+		goto fail;
+
+	EVP_CIPHER_CTX_set_padding(ctx, 0);
+
+	if (EVP_EncryptInit_ex(ctx, cipher, NULL, key, iv) != 1)
+		goto fail_ctx;
+
+	if (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, size) != 1)
+		goto fail_ctx;
+
+	ciphertext_len = len;
+
+	EVP_CIPHER_CTX_free(ctx);
+	return ciphertext_len;
+fail_ctx:
+	ERR_print_errors_fp(stderr);
+	EVP_CIPHER_CTX_free(ctx);
+	return -1;
+fail:
+	ERR_print_errors_fp(stderr);
+	return -1;
+}
+
+static size_t gen_essiv_salt(const void *iv, size_t iv_len, const void *key, size_t key_len, void *salt)
+{
+	size_t ret;
+	const EVP_CIPHER *cipher;
+	void *sha256 = xzalloc(EVP_MD_size(EVP_sha256()));
+
+	cipher = EVP_aes_256_ecb();
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-256-ECB is not supported");
+		return -1;
+	}
+
+	if (do_sha256(key, key_len, sha256) != 0) {
+		errmsg("sha256 failed");
+		return -1;
+	}
+
+	ret = do_encrypt(cipher, iv, iv_len, sha256, EVP_CIPHER_key_length(cipher), NULL, 0, salt);
+	if (ret != iv_len)
+		errmsg("Unable to compute ESSIV salt, return value %zi instead of %zi", ret, iv_len);
+
+	free(sha256);
+
+	return ret;
+}
+
+
+static ssize_t encrypt_block(const void *plaintext, size_t size,
+			     const void *key, uint64_t block_index,
+			     void *ciphertext, const EVP_CIPHER *cipher)
+{
+	size_t key_len, ret, ivsize;
+	void *essiv_salt, *iv;
+
+	ivsize = EVP_CIPHER_iv_length(cipher);
+	key_len = EVP_CIPHER_key_length(cipher);
+
+	iv = alloca(ivsize);
+	essiv_salt = alloca(ivsize);
+
+	memset(iv, 0, ivsize);
+	*((uint64_t *)iv) = cpu_to_le64(block_index);
+
+	gen_essiv_salt(iv, ivsize, key, key_len, essiv_salt);
+
+	ret = do_encrypt(cipher, plaintext, size, key, key_len,
+			 essiv_salt, ivsize, ciphertext);
+	return ret;
+}
+
+ssize_t encrypt_block_aes128_cbc(const void *plaintext, size_t size,
+				 const void *key, uint64_t block_index,
+				 void *ciphertext)
+{
+	const EVP_CIPHER *cipher = EVP_aes_128_cbc();
+
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-128-CBC is not supported");
+		return -1;
+	}
+	return encrypt_block(plaintext, size, key, block_index,
+			     ciphertext, cipher);
+}
+
+ssize_t encrypt_block_aes256_xts(const void *plaintext, size_t size,
+				 const void *key, uint64_t block_index,
+				 void *ciphertext)
+{
+	const EVP_CIPHER *cipher = EVP_aes_256_xts();
+
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-256-XTS is not supported");
+		return -1;
+	}
+	return encrypt_block(plaintext, size, key, block_index,
+			     ciphertext, cipher);
+}
+
+static void block_swap(uint8_t *ciphertext, size_t i0, size_t i1,
+			size_t size)
+{
+	uint8_t temp[size], *p0, *p1;
+
+	p0 = ciphertext + i0 * size;
+	p1 = ciphertext + i1 * size;
+
+	memcpy(temp, p0, size);
+	memcpy(p0, p1, size);
+	memcpy(p1, temp, size);
+}
+
+static ssize_t encrypt_cbc_cts(const void *plaintext, size_t size,
+			       const void *key, void *ciphertext,
+			       const EVP_CIPHER *cipher)
+{
+	size_t diff, padded_size, count, ivsize;
+	uint8_t iv[EVP_MAX_IV_LENGTH], *padded;
+	ssize_t ret, key_len;
+
+	key_len = EVP_CIPHER_key_length(cipher);
+	ivsize = EVP_CIPHER_iv_length(cipher);
+
+	memset(iv, 0, ivsize);
+
+	diff = size % key_len;
+
+	if (diff) {
+		padded_size = size - diff + key_len;
+		padded = size > 256 ? malloc(padded_size) : alloca(padded_size);
+
+		memcpy(padded, plaintext, size);
+		memset(padded + size, 0, padded_size - size);
+
+		ret = do_encrypt(cipher, padded, padded_size, key, key_len,
+				 iv, sizeof(iv), ciphertext);
+
+		if (size > 256)
+			free(padded);
+	} else {
+		ret = do_encrypt(cipher, plaintext, size, key, key_len,
+				 iv, sizeof(iv), ciphertext);
+	}
+
+	if (ret < 0)
+		return ret;
+
+	count = ret / key_len;
+
+	if (count > 1)
+		block_swap(ciphertext, count - 2, count - 1, key_len);
+
+	return size;
+}
+
+ssize_t encrypt_aes128_cbc_cts(const void *plaintext, size_t size,
+				const void *key, void *ciphertext)
+{
+	const EVP_CIPHER *cipher = EVP_aes_128_cbc();
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-128-CBC is not supported");
+		return -1;
+	}
+
+	return encrypt_cbc_cts(plaintext, size, key, ciphertext, cipher);
+}
+
+ssize_t encrypt_aes256_cbc_cts(const void *plaintext, size_t size,
+				const void *key, void *ciphertext)
+{
+	const EVP_CIPHER *cipher = EVP_aes_256_cbc();
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-256-CBC is not supported");
+		return -1;
+	}
+
+	return encrypt_cbc_cts(plaintext, size, key, ciphertext, cipher);
+}
+
+ssize_t derive_key_aes(const void *deriving_key, const void *source_key,
+		       void *derived_key)
+{
+	const EVP_CIPHER *cipher;
+	size_t aes_key_len;
+
+	cipher = EVP_aes_128_ecb();
+	if (!cipher) {
+		errmsg("OpenSSL: Cipher AES-128-ECB is not supported");
+		return -1;
+	}
+	aes_key_len = EVP_CIPHER_key_length(cipher);
+
+	return do_encrypt(cipher, source_key, aes_key_len, deriving_key,
+			  aes_key_len, NULL, 0, derived_key);
+}
+
+int crypto_init(void)
+{
+	ERR_load_crypto_strings();
+	return 0;
+}
+
+void crypto_cleanup(void)
+{
+	EVP_cleanup();
+	ERR_free_strings();
+}
+
+struct cipher *get_cipher(const char *name)
+{
+	size_t i;
+
+	for (i = 0; i < sizeof(ciphers) / sizeof(ciphers[0]); ++i) {
+		if (!strcmp(ciphers[i].name, name))
+			return ciphers + i;
+	}
+
+	return NULL;
+}
+
+void list_ciphers(FILE *fp)
+{
+	size_t i;
+
+	for (i = 0; i < sizeof(ciphers) / sizeof(ciphers[0]); ++i) {
+		fprintf(fp, "\t%s\n", ciphers[i].name);
+	}
+}