mirror of
https://github.com/vanhoefm/fragattacks.git
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0a11409c00
Previously, it was possible for the loop through the data components to increment addr/len index at the last position beyond the declared size. This resulted in reading beyond those arrays. The read values were not used and as such, this was unlikely to cause noticeable issues, but anyway, memory checkers can detect this and the correct behavior is to stop increments before going beyond the arrays since no more bytes will be processed after this anyway. Signed-off-by: Jouni Malinen <j@w1.fi>
132 lines
3.1 KiB
C
132 lines
3.1 KiB
C
/*
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* One-key CBC MAC (OMAC1) hash with AES-128
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*
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* Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
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*
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* This software may be distributed under the terms of the BSD license.
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* See README for more details.
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*/
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#include "includes.h"
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#include "common.h"
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#include "aes.h"
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#include "aes_wrap.h"
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static void gf_mulx(u8 *pad)
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{
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int i, carry;
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carry = pad[0] & 0x80;
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for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
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pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
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pad[AES_BLOCK_SIZE - 1] <<= 1;
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if (carry)
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pad[AES_BLOCK_SIZE - 1] ^= 0x87;
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}
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/**
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* omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
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* @key: 128-bit key for the hash operation
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* @num_elem: Number of elements in the data vector
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* @addr: Pointers to the data areas
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* @len: Lengths of the data blocks
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* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*
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* This is a mode for using block cipher (AES in this case) for authentication.
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* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
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* (SP) 800-38B.
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*/
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int omac1_aes_128_vector(const u8 *key, size_t num_elem,
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const u8 *addr[], const size_t *len, u8 *mac)
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{
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void *ctx;
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u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
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const u8 *pos, *end;
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size_t i, e, left, total_len;
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memset(cbc, 0, AES_BLOCK_SIZE);
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total_len = 0;
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for (e = 0; e < num_elem; e++)
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total_len += len[e];
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left = total_len;
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e = 0;
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pos = addr[0];
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end = pos + len[0];
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while (left >= AES_BLOCK_SIZE) {
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for (i = 0; i < AES_BLOCK_SIZE; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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/*
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* Stop if there are no more bytes to process
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* since there are no more entries in the array.
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*/
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if (i + 1 == AES_BLOCK_SIZE &&
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left == AES_BLOCK_SIZE)
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break;
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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if (left > AES_BLOCK_SIZE)
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aes_encrypt(ctx, cbc, cbc);
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left -= AES_BLOCK_SIZE;
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}
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os_memset(pad, 0, AES_BLOCK_SIZE);
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aes_encrypt(ctx, pad, pad);
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gf_mulx(pad);
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if (left || total_len == 0) {
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for (i = 0; i < left; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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/*
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* Stop if there are no more bytes to process
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* since there are no more entries in the array.
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*/
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if (i + 1 == left)
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break;
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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cbc[left] ^= 0x80;
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gf_mulx(pad);
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}
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for (i = 0; i < AES_BLOCK_SIZE; i++)
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pad[i] ^= cbc[i];
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aes_encrypt(ctx, pad, mac);
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aes_encrypt_deinit(ctx);
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return 0;
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}
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/**
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* omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
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* @key: 128-bit key for the hash operation
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* @data: Data buffer for which a MAC is determined
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* @data_len: Length of data buffer in bytes
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* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*
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* This is a mode for using block cipher (AES in this case) for authentication.
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* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
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* (SP) 800-38B.
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*/
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int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
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{
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return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
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}
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