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PACKET: add methods for reading length-prefixed TLS vectors.

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Rewrite ssl3_get_client_hello to use the new methods.

Reviewed-by: Matt Caswell <matt@openssl.org>
This commit is contained in:
Emilia Kasper 2015-08-18 12:29:36 +02:00
parent 9cc3e8f1f2
commit ec30e8566e
3 changed files with 213 additions and 54 deletions
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82
ssl/packet_locl.h
View File

@ -87,6 +87,17 @@ __owur static inline size_t PACKET_remaining(const PACKET *pkt)
return (size_t)(pkt->end - pkt->curr);
}
/*
* Returns a pointer to the PACKET's current position.
* For use in non-PACKETized APIs.
* TODO(openssl-team): this should return 'const unsigned char*' but can't
* currently because legacy code passes 'unsigned char*'s around.
*/
static inline unsigned char *PACKET_data(const PACKET *pkt)
{
return pkt->curr;
}
/*
* Initialise a PACKET with |len| bytes held in |buf|. This does not make a
* copy of the data so |buf| must be present for the whole time that the PACKET
@ -388,6 +399,77 @@ __owur static inline int PACKET_length(const PACKET *pkt, size_t *len)
return 1;
}
/*
* Reads a variable-length vector prefixed with a one-byte length, and stores
* the contents in |subpkt|. |pkt| can equal |subpkt|.
* Data is not copied: the |subpkt| packet will share its underlying buffer with
* the original |pkt|, so data wrapped by |pkt| must outlive the |subpkt|.
* Upon failure, the original |pkt| and |subpkt| are not modified.
*/
__owur static inline int PACKET_get_length_prefixed_1(PACKET *pkt, PACKET *subpkt)
{
unsigned int length;
unsigned char *data;
PACKET tmp = *pkt;
if (!PACKET_get_1(&tmp, &length) ||
!PACKET_get_bytes(&tmp, &data, (size_t)length)) {
return 0;
}
*pkt = tmp;
subpkt->start = subpkt->curr = data;
subpkt->end = subpkt->start + length;
return 1;
}
/*
* Reads a variable-length vector prefixed with a two-byte length, and stores
* the contents in |subpkt|. |pkt| can equal |subpkt|.
* Data is not copied: the |subpkt| packet will share its underlying buffer with
* the original |pkt|, so data wrapped by |pkt| must outlive the |subpkt|.
* Upon failure, the original |pkt| and |subpkt| are not modified.
*/
__owur static inline int PACKET_get_length_prefixed_2(PACKET *pkt, PACKET *subpkt)
{
unsigned int length;
unsigned char *data;
PACKET tmp = *pkt;
if (!PACKET_get_net_2(&tmp, &length) ||
!PACKET_get_bytes(&tmp, &data, (size_t)length)) {
return 0;
}
*pkt = tmp;
subpkt->start = subpkt->curr = data;
subpkt->end = subpkt->start + length;
return 1;
}
/*
* Reads a variable-length vector prefixed with a three-byte length, and stores
* the contents in |subpkt|. |pkt| can equal |subpkt|.
* Data is not copied: the |subpkt| packet will share its underlying buffer with
* the original |pkt|, so data wrapped by |pkt| must outlive the |subpkt|.
* Upon failure, the original |pkt| and |subpkt| are not modified.
*/
__owur static inline int PACKET_get_length_prefixed_3(PACKET *pkt, PACKET *subpkt)
{
unsigned long length;
unsigned char *data;
PACKET tmp = *pkt;
if (!PACKET_get_net_3(&tmp, &length) ||
!PACKET_get_bytes(&tmp, &data, (size_t)length)) {
return 0;
}
*pkt = tmp;
subpkt->start = subpkt->curr = data;
subpkt->end = subpkt->start + length;
return 1;
}
# ifdef __cplusplus
}
# endif

101
ssl/s3_srvr.c
View File

@ -838,19 +838,16 @@ int ssl3_send_hello_request(SSL *s)
int ssl3_get_client_hello(SSL *s)
{
int i, ok, al = SSL_AD_INTERNAL_ERROR, ret = -1;
unsigned int j, cipherlen, complen;
unsigned int cookie_len = 0;
unsigned int j, complen = 0;
long n;
unsigned long id;
SSL_CIPHER *c;
#ifndef OPENSSL_NO_COMP
unsigned char *q = NULL;
SSL_COMP *comp = NULL;
#endif
STACK_OF(SSL_CIPHER) *ciphers = NULL;
int protverr = 1;
PACKET pkt;
unsigned char *sess, *cdata;
PACKET pkt, cipher_suite, compression;
if (s->state == SSL3_ST_SR_CLNT_HELLO_C && !s->first_packet)
goto retry_cert;
@ -1013,30 +1010,31 @@ int ssl3_get_client_hello(SSL *s)
* Note, this is only for SSLv3+ using the backward compatible format.
* Real SSLv2 is not supported, and is rejected above.
*/
unsigned int csl, sil, cl;
unsigned int cipher_len, session_id_len, challenge_len;
if (!PACKET_get_net_2(&pkt, &csl)
|| !PACKET_get_net_2(&pkt, &sil)
|| !PACKET_get_net_2(&pkt, &cl)) {
if (!PACKET_get_net_2(&pkt, &cipher_len)
|| !PACKET_get_net_2(&pkt, &session_id_len)
|| !PACKET_get_net_2(&pkt, &challenge_len)) {
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_RECORD_LENGTH_MISMATCH);
al = SSL_AD_DECODE_ERROR;
goto f_err;
}
if (csl == 0) {
if (cipher_len == 0) {
/* we need at least one cipher */
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_NO_CIPHERS_SPECIFIED);
goto f_err;
}
if (!PACKET_get_bytes(&pkt, &cdata, csl)) {
if (!PACKET_get_sub_packet(&pkt, &cipher_suite, cipher_len)) {
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_RECORD_LENGTH_MISMATCH);
al = SSL_AD_DECODE_ERROR;
goto f_err;
}
if (ssl_bytes_to_cipher_list(s, cdata, csl, &(ciphers), 1) == NULL) {
if (ssl_bytes_to_cipher_list(s, PACKET_data(&cipher_suite),
cipher_len, &(ciphers), 1) == NULL) {
goto err;
}
@ -1044,7 +1042,7 @@ int ssl3_get_client_hello(SSL *s)
* Ignore any session id. We don't allow resumption in a backwards
* compatible ClientHello
*/
if (!PACKET_forward(&pkt, sil)) {
if (!PACKET_forward(&pkt, session_id_len)) {
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_RECORD_LENGTH_MISMATCH);
al = SSL_AD_DECODE_ERROR;
goto f_err;
@ -1055,27 +1053,24 @@ int ssl3_get_client_hello(SSL *s)
goto err;
/* Load the client random */
i = (cl > SSL3_RANDOM_SIZE) ? SSL3_RANDOM_SIZE : cl;
i = challenge_len > SSL3_RANDOM_SIZE ? SSL3_RANDOM_SIZE : challenge_len;
memset(s->s3->client_random, 0, SSL3_RANDOM_SIZE);
if (!PACKET_peek_copy_bytes(&pkt,
s->s3->client_random + SSL3_RANDOM_SIZE - i,
i)
|| !PACKET_forward(&pkt, cl)
|| !PACKET_forward(&pkt, challenge_len)
|| PACKET_remaining(&pkt) != 0) {
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_RECORD_LENGTH_MISMATCH);
al = SSL_AD_DECODE_ERROR;
goto f_err;
}
/* No compression, so set complen to 0 */
complen = 0;
} else {
/* If we get here we've got SSLv3+ in an SSLv3+ record */
PACKET session_id;
unsigned int cookie_len;
/* load the client random and get the session-id */
if (!PACKET_copy_bytes(&pkt, s->s3->client_random, SSL3_RANDOM_SIZE)
|| !PACKET_get_1(&pkt, &j)
|| !PACKET_get_bytes(&pkt, &sess, j)) {
|| !PACKET_get_length_prefixed_1(&pkt, &session_id)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
@ -1117,7 +1112,13 @@ int ssl3_get_client_hello(SSL *s)
if (!ssl_get_new_session(s, 1))
goto err;
} else {
i = ssl_get_prev_session(s, &pkt, sess, j);
/*
* TODO(openssl-team): ssl_get_prev_session passes a non-const
* 'unsigned char*' session id to a user callback. Grab a copy of
* the data?
*/
i = ssl_get_prev_session(s, &pkt, PACKET_data(&session_id),
PACKET_remaining(&session_id));
/*
* Only resume if the session's version matches the negotiated
* version.
@ -1140,11 +1141,13 @@ int ssl3_get_client_hello(SSL *s)
}
if (SSL_IS_DTLS(s)) {
if (!PACKET_get_1(&pkt, &cookie_len)) {
PACKET cookie;
if (!PACKET_get_length_prefixed_1(&pkt, &cookie)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
cookie_len = PACKET_remaining(&cookie);
/*
* The ClientHello may contain a cookie even if the
* HelloVerify message has not been sent--make sure that it
@ -1161,10 +1164,13 @@ int ssl3_get_client_hello(SSL *s)
if ((SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE)
&& cookie_len > 0) {
/* Get cookie */
if (!PACKET_copy_bytes(&pkt, s->d1->rcvd_cookie,
cookie_len)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
/*
* TODO(openssl-team): rcvd_cookie appears unused outside this
* function. Remove the field?
*/
if (!PACKET_copy_bytes(&cookie, s->d1->rcvd_cookie, cookie_len)) {
al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, ERR_R_INTERNAL_ERROR);
goto f_err;
}
@ -1187,15 +1193,7 @@ int ssl3_get_client_hello(SSL *s)
}
/* Set to -2 so if successful we return 2 */
ret = -2;
} else {
/* Skip over cookie */
if (!PACKET_forward(&pkt, cookie_len)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
}
if (s->method->version == DTLS_ANY_VERSION) {
/* Select version to use */
if (s->client_version <= DTLS1_2_VERSION &&
@ -1223,26 +1221,21 @@ int ssl3_get_client_hello(SSL *s)
}
}
if (!PACKET_get_net_2(&pkt, &cipherlen)) {
if (!PACKET_get_length_prefixed_2(&pkt, &cipher_suite)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
if (cipherlen == 0) {
if (PACKET_remaining(&cipher_suite) == 0) {
al = SSL_AD_ILLEGAL_PARAMETER;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_NO_CIPHERS_SPECIFIED);
goto f_err;
}
if (!PACKET_get_bytes(&pkt, &cdata, cipherlen)) {
/* not enough data */
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
goto f_err;
}
if (ssl_bytes_to_cipher_list(s, cdata, cipherlen, &(ciphers), 0) == NULL) {
if (ssl_bytes_to_cipher_list(s, PACKET_data(&cipher_suite),
PACKET_remaining(&cipher_suite),
&(ciphers), 0) == NULL) {
goto err;
}
@ -1301,19 +1294,21 @@ int ssl3_get_client_hello(SSL *s)
}
/* compression */
if (!PACKET_get_1(&pkt, &complen)
|| !PACKET_get_bytes(&pkt, &cdata, complen)) {
if (!PACKET_get_length_prefixed_1(&pkt, &compression)) {
/* not enough data */
al = SSL_AD_DECODE_ERROR;
/*
* TODO(openssl-team):
* SSL_R_LENGTH_TOO_SHORT and SSL_R_LENGTH_MISMATCH are used
* interchangeably. Pick one.
*/
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO, SSL_R_LENGTH_MISMATCH);
goto f_err;
}
#ifndef OPENSSL_NO_COMP
q = cdata;
#endif
complen = PACKET_remaining(&compression);
for (j = 0; j < complen; j++) {
if (cdata[j] == 0)
if (PACKET_data(&compression)[j] == 0)
break;
}
@ -1415,7 +1410,7 @@ int ssl3_get_client_hello(SSL *s)
}
/* Look for resumed method in compression list */
for (k = 0; k < complen; k++) {
if (q[k] == comp_id)
if (PACKET_data(&compression)[k] == comp_id)
break;
}
if (k >= complen) {
@ -1436,7 +1431,7 @@ int ssl3_get_client_hello(SSL *s)
comp = sk_SSL_COMP_value(s->ctx->comp_methods, m);
v = comp->id;
for (o = 0; o < complen; o++) {
if (v == q[o]) {
if (v == PACKET_data(&compression)[o]) {
done = 1;
break;
}

84
test/packettest.c
View File

@ -281,6 +281,85 @@ static int test_PACKET_buf_init()
return 1;
}
static int test_PACKET_get_length_prefixed_1()
{
unsigned char buf[BUF_LEN];
const size_t len = 16;
unsigned int i;
PACKET pkt, short_pkt, subpkt;
buf[0] = len;
for (i = 1; i < BUF_LEN; i++) {
buf[i] = (i * 2) & 0xff;
}
if ( !PACKET_buf_init(&pkt, buf, BUF_LEN)
|| !PACKET_buf_init(&short_pkt, buf, len)
|| !PACKET_get_length_prefixed_1(&pkt, &subpkt)
|| PACKET_remaining(&subpkt) != len
|| !PACKET_get_net_2(&subpkt, &i)
|| i != 0x0204
|| PACKET_get_length_prefixed_1(&short_pkt, &subpkt)
|| PACKET_remaining(&short_pkt) != len) {
fprintf(stderr, "test_PACKET_get_length_prefixed_1() failed\n");
return 0;
}
return 1;
}
static int test_PACKET_get_length_prefixed_2()
{
unsigned char buf[1024];
const size_t len = 516; /* 0x0204 */
unsigned int i;
PACKET pkt, short_pkt, subpkt;
for (i = 1; i <= 1024; i++) {
buf[i-1] = (i * 2) & 0xff;
}
if ( !PACKET_buf_init(&pkt, buf, 1024)
|| !PACKET_buf_init(&short_pkt, buf, len)
|| !PACKET_get_length_prefixed_2(&pkt, &subpkt)
|| PACKET_remaining(&subpkt) != len
|| !PACKET_get_net_2(&subpkt, &i)
|| i != 0x0608
|| PACKET_get_length_prefixed_2(&short_pkt, &subpkt)
|| PACKET_remaining(&short_pkt) != len) {
fprintf(stderr, "test_PACKET_get_length_prefixed_2() failed\n");
return 0;
}
return 1;
}
static int test_PACKET_get_length_prefixed_3()
{
unsigned char buf[1024];
const size_t len = 516; /* 0x000204 */
unsigned int i;
PACKET pkt, short_pkt, subpkt;
for (i = 0; i < 1024; i++) {
buf[i] = (i * 2) & 0xff;
}
if ( !PACKET_buf_init(&pkt, buf, 1024)
|| !PACKET_buf_init(&short_pkt, buf, len)
|| !PACKET_get_length_prefixed_3(&pkt, &subpkt)
|| PACKET_remaining(&subpkt) != len
|| !PACKET_get_net_2(&subpkt, &i)
|| i != 0x0608
|| PACKET_get_length_prefixed_3(&short_pkt, &subpkt)
|| PACKET_remaining(&short_pkt) != len) {
fprintf(stderr, "test_PACKET_get_length_prefixed_3() failed\n");
return 0;
}
return 1;
}
int main(int argc, char **argv)
{
unsigned char buf[BUF_LEN];
@ -309,7 +388,10 @@ int main(int argc, char **argv)
|| !test_PACKET_get_sub_packet(&pkt, start)
|| !test_PACKET_get_bytes(&pkt, start)
|| !test_PACKET_copy_bytes(&pkt, start)
|| !test_PACKET_move_funcs(&pkt, start)) {
|| !test_PACKET_move_funcs(&pkt, start)
|| !test_PACKET_get_length_prefixed_1()
|| !test_PACKET_get_length_prefixed_2()
|| !test_PACKET_get_length_prefixed_3()) {
return 1;
}
printf("PASS\n");