/*
*
* BlueZ - Bluetooth protocol stack for Linux
*
* Copyright (C) 2012-2014 Intel Corporation. All rights reserved.
*
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include "src/shared/util.h"
#include "src/shared/crypto.h"
#ifndef HAVE_LINUX_IF_ALG_H
#ifndef HAVE_LINUX_TYPES_H
typedef uint8_t __u8;
typedef uint16_t __u16;
typedef uint32_t __u32;
#else
#include <linux/types.h>
#endif
struct sockaddr_alg {
__u16 salg_family;
__u8 salg_type[14];
__u32 salg_feat;
__u32 salg_mask;
__u8 salg_name[64];
};
struct af_alg_iv {
__u32 ivlen;
__u8 iv[0];
};
#define ALG_SET_KEY 1
#define ALG_SET_IV 2
#define ALG_SET_OP 3
#define ALG_OP_DECRYPT 0
#define ALG_OP_ENCRYPT 1
#define PF_ALG 38 /* Algorithm sockets. */
#define AF_ALG PF_ALG
#else
#include <linux/if_alg.h>
#endif
#ifndef SOL_ALG
#define SOL_ALG 279
#endif
/* Maximum message length that can be passed to aes_cmac */
#define CMAC_MSG_MAX 80
struct bt_crypto {
int ref_count;
int ecb_aes;
int urandom;
int cmac_aes;
};
static int urandom_setup(void)
{
int fd;
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0)
return -1;
return fd;
}
static int ecb_aes_setup(void)
{
struct sockaddr_alg salg;
int fd;
fd = socket(PF_ALG, SOCK_SEQPACKET | SOCK_CLOEXEC, 0);
if (fd < 0)
return -1;
memset(&salg, 0, sizeof(salg));
salg.salg_family = AF_ALG;
strcpy((char *) salg.salg_type, "skcipher");
strcpy((char *) salg.salg_name, "ecb(aes)");
if (bind(fd, (struct sockaddr *) &salg, sizeof(salg)) < 0) {
close(fd);
return -1;
}
return fd;
}
static int cmac_aes_setup(void)
{
struct sockaddr_alg salg;
int fd;
fd = socket(PF_ALG, SOCK_SEQPACKET | SOCK_CLOEXEC, 0);
if (fd < 0)
return -1;
memset(&salg, 0, sizeof(salg));
salg.salg_family = AF_ALG;
strcpy((char *) salg.salg_type, "hash");
strcpy((char *) salg.salg_name, "cmac(aes)");
if (bind(fd, (struct sockaddr *) &salg, sizeof(salg)) < 0) {
close(fd);
return -1;
}
return fd;
}
struct bt_crypto *bt_crypto_new(void)
{
struct bt_crypto *crypto;
crypto = new0(struct bt_crypto, 1);
crypto->ecb_aes = ecb_aes_setup();
if (crypto->ecb_aes < 0) {
free(crypto);
return NULL;
}
crypto->urandom = urandom_setup();
if (crypto->urandom < 0) {
close(crypto->ecb_aes);
free(crypto);
return NULL;
}
crypto->cmac_aes = cmac_aes_setup();
if (crypto->cmac_aes < 0) {
close(crypto->urandom);
close(crypto->ecb_aes);
free(crypto);
return NULL;
}
return bt_crypto_ref(crypto);
}
struct bt_crypto *bt_crypto_ref(struct bt_crypto *crypto)
{
if (!crypto)
return NULL;
__sync_fetch_and_add(&crypto->ref_count, 1);
return crypto;
}
void bt_crypto_unref(struct bt_crypto *crypto)
{
if (!crypto)
return;
if (__sync_sub_and_fetch(&crypto->ref_count, 1))
return;
close(crypto->urandom);
close(crypto->ecb_aes);
close(crypto->cmac_aes);
free(crypto);
}
bool bt_crypto_random_bytes(struct bt_crypto *crypto,
void *buf, uint8_t num_bytes)
{
ssize_t len;
if (!crypto)
return false;
len = read(crypto->urandom, buf, num_bytes);
if (len < num_bytes)
return false;
return true;
}
static int alg_new(int fd, const void *keyval, socklen_t keylen)
{
if (setsockopt(fd, SOL_ALG, ALG_SET_KEY, keyval, keylen) < 0)
return -1;
/* FIXME: This should use accept4() with SOCK_CLOEXEC */
return accept(fd, NULL, 0);
}
static bool alg_encrypt(int fd, const void *inbuf, size_t inlen,
void *outbuf, size_t outlen)
{
__u32 alg_op = ALG_OP_ENCRYPT;
char cbuf[CMSG_SPACE(sizeof(alg_op))];
struct cmsghdr *cmsg;
struct msghdr msg;
struct iovec iov;
ssize_t len;
memset(cbuf, 0, sizeof(cbuf));
memset(&msg, 0, sizeof(msg));
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_ALG;
cmsg->cmsg_type = ALG_SET_OP;
cmsg->cmsg_len = CMSG_LEN(sizeof(alg_op));
memcpy(CMSG_DATA(cmsg), &alg_op, sizeof(alg_op));
iov.iov_base = (void *) inbuf;
iov.iov_len = inlen;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
len = sendmsg(fd, &msg, 0);
if (len < 0)
return false;
len = read(fd, outbuf, outlen);
if (len < 0)
return false;
return true;
}
static inline void swap_buf(const uint8_t *src, uint8_t *dst, uint16_t len)
{
int i;
for (i = 0; i < len; i++)
dst[len - 1 - i] = src[i];
}
bool bt_crypto_sign_att(struct bt_crypto *crypto, const uint8_t key[16],
const uint8_t *m, uint16_t m_len,
uint32_t sign_cnt, uint8_t signature[12])
{
int fd;
int len;
uint8_t tmp[16], out[16];
uint16_t msg_len = m_len + sizeof(uint32_t);
uint8_t msg[msg_len];
uint8_t msg_s[msg_len];
if (!crypto)
return false;
memset(msg, 0, msg_len);
memcpy(msg, m, m_len);
/* Add sign_counter to the message */
put_le32(sign_cnt, msg + m_len);
/* The most significant octet of key corresponds to key[0] */
swap_buf(key, tmp, 16);
fd = alg_new(crypto->cmac_aes, tmp, 16);
if (fd < 0)
return false;
/* Swap msg before signing */
swap_buf(msg, msg_s, msg_len);
len = send(fd, msg_s, msg_len, 0);
if (len < 0) {
close(fd);
return false;
}
len = read(fd, out, 16);
if (len < 0) {
close(fd);
return false;
}
close(fd);
/*
* As to BT spec. 4.1 Vol[3], Part C, chapter 10.4.1 sign counter should
* be placed in the signature
*/
put_be32(sign_cnt, out + 8);
/*
* The most significant octet of hash corresponds to out[0] - swap it.
* Then truncate in most significant bit first order to a length of
* 12 octets
*/
swap_buf(out, tmp, 16);
memcpy(signature, tmp + 4, 12);
return true;
}
/*
* Security function e
*
* Security function e generates 128-bit encryptedData from a 128-bit key
* and 128-bit plaintextData using the AES-128-bit block cypher:
*
* encryptedData = e(key, plaintextData)
*
* The most significant octet of key corresponds to key[0], the most
* significant octet of plaintextData corresponds to in[0] and the
* most significant octet of encryptedData corresponds to out[0].
*
*/
bool bt_crypto_e(struct bt_crypto *crypto, const uint8_t key[16],
const uint8_t plaintext[16], uint8_t encrypted[16])
{
uint8_t tmp[16], in[16], out[16];
int fd;
if (!crypto)
return false;
/* The most significant octet of key corresponds to key[0] */
swap_buf(key, tmp, 16);
fd = alg_new(crypto->ecb_aes, tmp, 16);
if (fd < 0)
return false;
/* Most significant octet of plaintextData corresponds to in[0] */
swap_buf(plaintext, in, 16);
if (!alg_encrypt(fd, in, 16, out, 16)) {
close(fd);
return false;
}
/* Most significant octet of encryptedData corresponds to out[0] */
swap_buf(out, encrypted, 16);
close(fd);
return true;
}
/*
* Random Address Hash function ah
*
* The random address hash function ah is used to generate a hash value
* that is used in resolvable private addresses.
*
* The following are inputs to the random address hash function ah:
*
* k is 128 bits
* r is 24 bits
* padding is 104 bits
*
* r is concatenated with padding to generate r' which is used as the
* 128-bit input parameter plaintextData to security function e:
*
* r' = padding || r
*
* The least significant octet of r becomes the least significant octet
* of r’ and the most significant octet of padding becomes the most
* significant octet of r'.
*
* For example, if the 24-bit value r is 0x423456 then r' is
* 0x00000000000000000000000000423456.
*
* The output of the random address function ah is:
*
* ah(k, r) = e(k, r') mod 2^24
*
* The output of the security function e is then truncated to 24 bits by
* taking the least significant 24 bits of the output of e as the result
* of ah.
*/
bool bt_crypto_ah(struct bt_crypto *crypto, const uint8_t k[16],
const uint8_t r[3], uint8_t hash[3])
{
uint8_t rp[16];
uint8_t encrypted[16];
if (!crypto)
return false;
/* r' = padding || r */
memcpy(rp, r, 3);
memset(rp + 3, 0, 13);
/* e(k, r') */
if (!bt_crypto_e(crypto, k, rp, encrypted))
return false;
/* ah(k, r) = e(k, r') mod 2^24 */
memcpy(hash, encrypted, 3);
return true;
}
typedef struct {
uint64_t a, b;
} u128;
static inline void u128_xor(const uint8_t p[16], const uint8_t q[16],
uint8_t r[16])
{
u128 pp, qq, rr;
memcpy(&pp, p, 16);
memcpy(&qq, q, 16);
rr.a = pp.a ^ qq.a;
rr.b = pp.b ^ qq.b;
memcpy(r, &rr, 16);
}
/*
* Confirm value generation function c1
*
* During the pairing process confirm values are exchanged. This confirm
* value generation function c1 is used to generate the confirm values.
*
* The following are inputs to the confirm value generation function c1:
*
* k is 128 bits
* r is 128 bits
* pres is 56 bits
* preq is 56 bits
* iat is 1 bit
* ia is 48 bits
* rat is 1 bit
* ra is 48 bits
* padding is 32 bits of 0
*
* iat is concatenated with 7-bits of 0 to create iat' which is 8 bits
* in length. iat is the least significant bit of iat'
*
* rat is concatenated with 7-bits of 0 to create rat' which is 8 bits
* in length. rat is the least significant bit of rat'
*
* pres, preq, rat' and iat' are concatenated to generate p1 which is
* XORed with r and used as 128-bit input parameter plaintextData to
* security function e:
*
* p1 = pres || preq || rat' || iat'
*
* The octet of iat' becomes the least significant octet of p1 and the
* most significant octet of pres becomes the most significant octet of
* p1.
*
* ra is concatenated with ia and padding to generate p2 which is XORed
* with the result of the security function e using p1 as the input
* paremter plaintextData and is then used as the 128-bit input
* parameter plaintextData to security function e:
*
* p2 = padding || ia || ra
*
* The least significant octet of ra becomes the least significant octet
* of p2 and the most significant octet of padding becomes the most
* significant octet of p2.
*
* The output of the confirm value generation function c1 is:
*
* c1(k, r, preq, pres, iat, rat, ia, ra) = e(k, e(k, r XOR p1) XOR p2)
*
* The 128-bit output of the security function e is used as the result
* of confirm value generation function c1.
*/
bool bt_crypto_c1(struct bt_crypto *crypto, const uint8_t k[16],
const uint8_t r[16], const uint8_t pres[7],
const uint8_t preq[7], uint8_t iat,
const uint8_t ia[6], uint8_t rat,
const uint8_t ra[6], uint8_t res[16])
{
uint8_t p1[16], p2[16];
/* p1 = pres || preq || _rat || _iat */
p1[0] = iat;
p1[1] = rat;
memcpy(p1 + 2, preq, 7);
memcpy(p1 + 9, pres, 7);
/* p2 = padding || ia || ra */
memcpy(p2, ra, 6);
memcpy(p2 + 6, ia, 6);
memset(p2 + 12, 0, 4);
/* res = r XOR p1 */
u128_xor(r, p1, res);
/* res = e(k, res) */
if (!bt_crypto_e(crypto, k, res, res))
return false;
/* res = res XOR p2 */
u128_xor(res, p2, res);
/* res = e(k, res) */
return bt_crypto_e(crypto, k, res, res);
}
/*
* Key generation function s1
*
* The key generation function s1 is used to generate the STK during the
* pairing process.
*
* The following are inputs to the key generation function s1:
*
* k is 128 bits
* r1 is 128 bits
* r2 is 128 bits
*
* The most significant 64-bits of r1 are discarded to generate r1' and
* the most significant 64-bits of r2 are discarded to generate r2'.
*
* r1' is concatenated with r2' to generate r' which is used as the
* 128-bit input parameter plaintextData to security function e:
*
* r' = r1' || r2'
*
* The least significant octet of r2' becomes the least significant
* octet of r' and the most significant octet of r1' becomes the most
* significant octet of r'.
*
* The output of the key generation function s1 is:
*
* s1(k, r1, r2) = e(k, r')
*
* The 128-bit output of the security function e is used as the result
* of key generation function s1.
*/
bool bt_crypto_s1(struct bt_crypto *crypto, const uint8_t k[16],
const uint8_t r1[16], const uint8_t r2[16],
uint8_t res[16])
{
memcpy(res, r2, 8);
memcpy(res + 8, r1, 8);
return bt_crypto_e(crypto, k, res, res);
}
static bool aes_cmac(struct bt_crypto *crypto, const uint8_t key[16],
const uint8_t *msg, size_t msg_len, uint8_t res[16])
{
uint8_t key_msb[16], out[16], msg_msb[CMAC_MSG_MAX];
ssize_t len;
int fd;
if (msg_len > CMAC_MSG_MAX)
return false;
swap_buf(key, key_msb, 16);
fd = alg_new(crypto->cmac_aes, key_msb, 16);
if (fd < 0)
return false;
swap_buf(msg, msg_msb, msg_len);
len = send(fd, msg_msb, msg_len, 0);
if (len < 0) {
close(fd);
return false;
}
len = read(fd, out, 16);
if (len < 0) {
close(fd);
return false;
}
swap_buf(out, res, 16);
close(fd);
return true;
}
bool bt_crypto_f4(struct bt_crypto *crypto, uint8_t u[32], uint8_t v[32],
uint8_t x[16], uint8_t z, uint8_t res[16])
{
uint8_t m[65];
if (!crypto)
return false;
m[0] = z;
memcpy(&m[1], v, 32);
memcpy(&m[33], u, 32);
return aes_cmac(crypto, x, m, sizeof(m), res);
}
bool bt_crypto_f5(struct bt_crypto *crypto, uint8_t w[32], uint8_t n1[16],
uint8_t n2[16], uint8_t a1[7], uint8_t a2[7],
uint8_t mackey[16], uint8_t ltk[16])
{
uint8_t btle[4] = { 0x65, 0x6c, 0x74, 0x62 };
uint8_t salt[16] = { 0xbe, 0x83, 0x60, 0x5a, 0xdb, 0x0b, 0x37, 0x60,
0x38, 0xa5, 0xf5, 0xaa, 0x91, 0x83, 0x88, 0x6c };
uint8_t length[2] = { 0x00, 0x01 };
uint8_t m[53], t[16];
if (!aes_cmac(crypto, salt, w, 32, t))
return false;
memcpy(&m[0], length, 2);
memcpy(&m[2], a2, 7);
memcpy(&m[9], a1, 7);
memcpy(&m[16], n2, 16);
memcpy(&m[32], n1, 16);
memcpy(&m[48], btle, 4);
m[52] = 0; /* Counter */
if (!aes_cmac(crypto, t, m, sizeof(m), mackey))
return false;
m[52] = 1; /* Counter */
return aes_cmac(crypto, t, m, sizeof(m), ltk);
}
bool bt_crypto_f6(struct bt_crypto *crypto, uint8_t w[16], uint8_t n1[16],
uint8_t n2[16], uint8_t r[16], uint8_t io_cap[3],
uint8_t a1[7], uint8_t a2[7], uint8_t res[16])
{
uint8_t m[65];
memcpy(&m[0], a2, 7);
memcpy(&m[7], a1, 7);
memcpy(&m[14], io_cap, 3);
memcpy(&m[17], r, 16);
memcpy(&m[33], n2, 16);
memcpy(&m[49], n1, 16);
return aes_cmac(crypto, w, m, sizeof(m), res);
}
bool bt_crypto_g2(struct bt_crypto *crypto, uint8_t u[32], uint8_t v[32],
uint8_t x[16], uint8_t y[16], uint32_t *val)
{
uint8_t m[80], tmp[16];
memcpy(&m[0], y, 16);
memcpy(&m[16], v, 32);
memcpy(&m[48], u, 32);
if (!aes_cmac(crypto, x, m, sizeof(m), tmp))
return false;
*val = get_le32(tmp);
*val %= 1000000;
return true;
}
bool bt_crypto_h6(struct bt_crypto *crypto, const uint8_t w[16],
const uint8_t keyid[4], uint8_t res[16])
{
if (!aes_cmac(crypto, w, keyid, 4, res))
return false;
return true;
}
bool bt_crypto_gatt_hash(struct bt_crypto *crypto, struct iovec *iov,
size_t iov_len, uint8_t res[16])
{
const uint8_t key[16] = {};
ssize_t len;
int fd;
if (!crypto)
return false;
fd = alg_new(crypto->cmac_aes, key, 16);
if (fd < 0)
return false;
len = writev(fd, iov, iov_len);
if (len < 0) {
close(fd);
return false;
}
len = read(fd, res, 16);
if (len < 0) {
close(fd);
return false;
}
close(fd);
return true;
}