uencrypt: add support for mbedtls

This commit includes some additional changes:
 - better handling of iv and keys in openssl/wolfssl variants
 - fix compiler warnings and whitespace
 - build all 3 variants as separate packages
 - adjust the new package name in targets' DEVICE_PACKAGES
 - remove PKG_FLAGS:=nonshared

[Beeline SmartBox Flash - OK]
Tested-by: Mikhail Zhilkin <csharper2005@gmail.com>
[after test: replaced a hardcoded IV size of 16 by cipher_info->iv_size]
Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

1 files changed, 212 insertions, 0 deletions

diff --git a/package/utils/uencrypt/src/uencrypt-mbedtls.c b/package/utils/uencrypt/src/uencrypt-mbedtls.c
new file mode 100644
index 0000000000..731beaad0f
--- /dev/null
+++ b/package/utils/uencrypt/src/uencrypt-mbedtls.c
@@ -0,0 +1,212 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (C) 2023 Eneas Ulir de Queiroz
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <mbedtls/cipher.h>
+
+int do_crypt(FILE *infile, FILE *outfile, const mbedtls_cipher_info_t *cipher_info,
+	     const unsigned char *key, const unsigned char *iv, int enc, int padding)
+{
+    mbedtls_cipher_context_t ctx;
+    unsigned char inbuf[1024], outbuf[1024 + MBEDTLS_MAX_BLOCK_LENGTH];
+    size_t inlen, outlen;
+    int ret = 0;
+    int step;
+
+    mbedtls_cipher_init(&ctx);
+    if ((ret = mbedtls_cipher_setup(&ctx, cipher_info))) {
+	fprintf(stderr, "Error: mbedtls_cipher_setup: %d\n", ret);
+	goto out;
+    }
+    step = iv ? 1024 : mbedtls_cipher_get_block_size(&ctx);
+    if ((ret = mbedtls_cipher_setkey(&ctx, key, (int) mbedtls_cipher_get_key_bitlen(&ctx),
+			      enc ? MBEDTLS_ENCRYPT : MBEDTLS_DECRYPT))) {
+	fprintf(stderr, "Error: mbedtls_cipher_setkey: %d\n", ret);
+	goto out;
+    }
+    if (iv && (ret = mbedtls_cipher_set_iv(&ctx, iv, cipher_info->iv_size))) {
+	fprintf(stderr, "Error: mbedtls_cipher_set_iv: %d\n", ret);
+	goto out;
+    }
+
+    if (cipher_info->block_size > 1) {
+	if (cipher_info->mode == MBEDTLS_MODE_CBC) {
+	    if ((ret = mbedtls_cipher_set_padding_mode(&ctx,
+						       padding ? MBEDTLS_PADDING_PKCS7
+							       : MBEDTLS_PADDING_NONE))) {
+		fprintf(stderr, "Error: mbedtls_cipher_set_padding_mode: %d\n", ret);
+		goto out;
+	    }
+	} else {
+	    if (cipher_info->mode != MBEDTLS_MODE_CBC && padding) {
+		fprintf(stderr, "Error: mbedTLS only supports padding with CBC ciphers.\n");
+		goto out;
+	    }
+	}
+    }
+
+    if ((ret = mbedtls_cipher_reset(&ctx))) {
+	fprintf(stderr, "Error: mbedtls_cipher_reset: %d\n", ret);
+	goto out;
+    }
+
+    for (;;) {
+	inlen = fread(inbuf, 1, step, infile);
+	if (inlen <= 0)
+	    break;
+	if ((ret = mbedtls_cipher_update(&ctx, inbuf, inlen, outbuf, &outlen))) {
+	    fprintf(stderr, "Error: mbedtls_cipher_update: %d\n", ret);
+	    goto out;
+	}
+	fwrite(outbuf, 1, outlen, outfile);
+    }
+    if ((ret = mbedtls_cipher_finish(&ctx, outbuf, &outlen))) {
+	fprintf(stderr, "Error: mbedtls_cipher_finish: %d\n", ret);
+	goto out;
+    }
+    fwrite(outbuf, 1, outlen, outfile);
+
+out:
+    mbedtls_cipher_free(&ctx);
+    return ret;
+}
+
+static void check_enc_dec(const int enc)
+{
+    if (enc == -1)
+	return;
+    fprintf(stderr, "Error: both -d and -e were specified.\n");
+    exit(EXIT_FAILURE);
+}
+
+static void check_cipher(const mbedtls_cipher_info_t *cipher_info)
+{
+    const int *list;
+
+    if (cipher_info == NULL) {
+	fprintf(stderr, "Error: invalid cipher: %s.\n", optarg);
+	fprintf(stderr, "Supported ciphers: \n");
+	for (list = mbedtls_cipher_list(); *list; list++) {
+	    cipher_info = mbedtls_cipher_info_from_type(*list);
+	    if (!cipher_info)
+		continue;
+	    fprintf(stderr, "\t%s\n", cipher_info->name);
+	}
+	exit(EXIT_FAILURE);
+    }
+}
+
+static void show_usage(const char* name)
+{
+    fprintf(stderr, "Usage: %s: [-d | -e] [-n] -k key [-i iv] [-c cipher]\n"
+		    "-d = decrypt; -e = encrypt; -n = no padding\n", name);
+}
+
+char *hexstr2buf(const char *str, size_t *len)
+{
+    char *buf;
+    size_t inlen = strlen(str);
+
+    *len = 0;
+    if (inlen % 2)
+	return NULL;
+
+    *len = inlen >> 1;
+    buf = malloc(*len);
+    for  (size_t x = 0; x < *len; x++)
+	sscanf(str + x * 2, "%2hhx", buf + x);
+    return buf;
+}
+
+static char* upperstr(char *str) {
+    for (char *s = str; *s; s++)
+	*s = toupper((unsigned char) *s);
+    return str;
+}
+
+int main(int argc, char *argv[])
+{
+    int enc = -1;
+    unsigned char *iv = NULL;
+    unsigned char *key = NULL;
+    size_t keylen = 0, ivlen = 0;
+    int opt;
+    int padding = 1;
+    const mbedtls_cipher_info_t *cipher_info =
+			mbedtls_cipher_info_from_type (MBEDTLS_CIPHER_AES_128_CBC);
+    int ret;
+
+    while ((opt = getopt(argc, argv, "c:dei:k:n")) != -1) {
+	switch (opt) {
+	case 'c':
+	    cipher_info = mbedtls_cipher_info_from_string(upperstr(optarg));
+	    check_cipher(cipher_info);
+	    break;
+	case 'd':
+	    check_enc_dec(enc);
+	    enc = 0;
+	    break;
+	case 'e':
+	    check_enc_dec(enc);
+	    enc = 1;
+	    break;
+	case 'i':
+	    iv = (unsigned char *) hexstr2buf((const char *)optarg, &ivlen);
+	    if (iv == NULL) {
+		fprintf(stderr, "Error setting IV to %s. The IV should be encoded in hex.\n",
+			optarg);
+		exit(EINVAL);
+	    }
+	    break;
+	case 'k':
+	    key = (unsigned char *) hexstr2buf((const char *)optarg, &keylen);
+	    if (key == NULL) {
+		fprintf(stderr, "Error setting key to %s. The key should be encoded in hex.\n",
+			optarg);
+		exit(EINVAL);
+	    }
+	    break;
+	case 'n':
+	    padding = 0;
+	    break;
+	default:
+	    show_usage(argv[0]);
+	    exit(EINVAL);
+	}
+    }
+    if (cipher_info->iv_size) {
+	if (iv == NULL) {
+	    fprintf(stderr, "Error: iv not set.\n");
+	    show_usage(argv[0]);
+	    exit(EXIT_FAILURE);
+	}
+	if (ivlen != cipher_info->iv_size) {
+	    fprintf(stderr, "Error: IV must be %d bytes; given IV is %zd bytes.\n",
+		    cipher_info->iv_size, ivlen);
+	    exit(EXIT_FAILURE);
+	}
+    }
+    if (key == NULL) {
+	fprintf(stderr, "Error: key not set.\n");
+	show_usage(argv[0]);
+	exit(EXIT_FAILURE);
+    }
+    if (keylen != cipher_info->key_bitlen >> 3) {
+	fprintf(stderr, "Error: key must be %d bytes; given key is %zd bytes.\n",
+		cipher_info->key_bitlen >> 3, keylen);
+	exit(EXIT_FAILURE);
+    }
+    ret = do_crypt(stdin, stdout, cipher_info, key, iv, !!enc, padding);
+    if (iv)
+	memset(iv, 0, ivlen);
+    memset(key, 0, keylen);
+    free(iv);
+    free(key);
+    return ret;
+}