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Tidy up EC parameter check code: instead of accessing internal structures

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add utility functions to t1_lib.c to check if EC certificates and parameters
are consistent with peer.
(backport from HEAD)
This commit is contained in:
Dr. Stephen Henson
2012-04-06 20:14:53 +00:00
parent 6b870763ac
commit c132ca95c0
3 changed files with 163 additions and 190 deletions
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184
ssl/t1_lib.c
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@@ -307,6 +307,30 @@ int tls1_ec_nid2curve_id(int nid)
return 0;
}
}
/* Get curves list, if "sess" is set return client curves otherwise
* preferred list
*/
static void tls1_get_curvelist(SSL *s, int sess,
const unsigned char **pcurves,
size_t *pcurveslen)
{
if (sess)
{
*pcurves = s->session->tlsext_ellipticcurvelist;
*pcurveslen = s->session->tlsext_ellipticcurvelist_length;
}
else
{
*pcurves = s->tlsext_ellipticcurvelist;
*pcurveslen = s->tlsext_ellipticcurvelist_length;
}
/* If not set use default: for now static structure */
if (!*pcurves)
{
*pcurves = eccurves_default;
*pcurveslen = sizeof(eccurves_default);
}
}
/* Return any common values from two lists. One list is used as a
* preference list where we return the most preferred match.
@@ -362,28 +386,10 @@ int tls1_shared_curve(SSL *s, int nmatch)
/* Can't do anything on client side */
if (s->server == 0)
return -1;
/* Use our preferred curve list, if not set use default */
if (s->tlsext_ellipticcurvelist)
{
l1 = s->tlsext_ellipticcurvelist;
l1len = s->tlsext_ellipticcurvelist_length;
}
else
{
l1 = eccurves_default;
l1len = sizeof(eccurves_default);
}
/* Use peer preferred curve list, if not set use default */
if(s->session->tlsext_ellipticcurvelist)
{
l2 = s->session->tlsext_ellipticcurvelist;
l2len =s->session->tlsext_ellipticcurvelist_length;
}
else
{
l2 = eccurves_default;
l2len = sizeof(eccurves_default);
}
/* Get supported curves */
tls1_get_curvelist(s, 0, &l1, &l1len);
tls1_get_curvelist(s, 1, &l2, &l2len);
id = tls1_shared_list(s, l1, l1len, l2, l2len, nmatch);
if (nmatch == -1)
return id;
@@ -466,6 +472,130 @@ int tls1_set_curves_list(unsigned char **pext, size_t *pextlen,
return 0;
return tls1_set_curves(pext, pextlen, ncb.nid_arr, ncb.nidcnt);
}
/* For an EC key set TLS id and required compression based on parameters */
static int tls1_set_ec_id(unsigned char *curve_id, unsigned char *comp_id,
EC_KEY *ec)
{
int is_prime, id;
const EC_GROUP *grp;
const EC_POINT *pt;
const EC_METHOD *meth;
if (!ec)
return 0;
/* Determine if it is a prime field */
grp = EC_KEY_get0_group(ec);
pt = EC_KEY_get0_public_key(ec);
if (!grp || !pt)
return 0;
meth = EC_GROUP_method_of(grp);
if (!meth)
return 0;
if (EC_METHOD_get_field_type(meth) == NID_X9_62_prime_field)
is_prime = 1;
else
is_prime = 0;
/* Determine curve ID */
id = EC_GROUP_get_curve_name(grp);
id = tls1_ec_nid2curve_id(id);
/* If we have an ID set it, otherwise set arbitrary explicit curve */
if (id)
{
curve_id[0] = 0;
curve_id[1] = (unsigned char)id;
}
else
{
curve_id[0] = 0xff;
if (is_prime)
curve_id[1] = 0x01;
else
curve_id[1] = 0x02;
}
if (comp_id)
{
if (EC_KEY_get_conv_form(ec) == POINT_CONVERSION_COMPRESSED)
{
if (is_prime)
*comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime;
else
*comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2;
}
else
*comp_id = TLSEXT_ECPOINTFORMAT_uncompressed;
}
return 1;
}
/* Check an EC key is compatible with extensions */
static int tls1_check_ec_key(SSL *s,
unsigned char *curve_id, unsigned char *comp_id)
{
const unsigned char *p;
size_t plen, i;
/* If point formats extension present check it, otherwise everything
* is supported (see RFC4492).
*/
if (comp_id && s->session->tlsext_ecpointformatlist)
{
p = s->session->tlsext_ecpointformatlist;
plen = s->session->tlsext_ecpointformatlist_length;
for (i = 0; i < plen; i++, p++)
{
if (*comp_id == *p)
break;
}
if (i == plen)
return 0;
}
/* If curve list present check it, otherwise everything is
* supported.
*/
if (s->session->tlsext_ellipticcurvelist)
{
p = s->session->tlsext_ellipticcurvelist;
plen = s->session->tlsext_ellipticcurvelist_length;
for (i = 0; i < plen; i+=2, p+=2)
{
if (p[0] == curve_id[0] && p[1] == curve_id[1])
return 1;
}
return 0;
}
return 1;
}
/* Check EC server key is compatible with client extensions */
int tls1_check_ec_server_key(SSL *s)
{
int rv;
CERT_PKEY *cpk = s->cert->pkeys + SSL_PKEY_ECC;
EVP_PKEY *pkey;
unsigned char comp_id, curve_id[2];
if (!cpk->x509 || !cpk->privatekey)
return 0;
pkey = X509_get_pubkey(cpk->x509);
if (!pkey)
return 0;
rv = tls1_set_ec_id(curve_id, &comp_id, pkey->pkey.ec);
EVP_PKEY_free(pkey);
if (!rv)
return 0;
return tls1_check_ec_key(s, curve_id, &comp_id);
}
/* Check EC temporary key is compatible with client extensions */
int tls1_check_ec_tmp_key(SSL *s)
{
unsigned char curve_id[2];
EC_KEY *ec = s->cert->ecdh_tmp;
if (!ec)
{
if (s->cert->ecdh_tmp_cb)
return 1;
else
return 0;
}
if (!tls1_set_ec_id(curve_id, NULL, ec))
return 1;
return tls1_check_ec_key(s, curve_id, NULL);
}
#endif /* OPENSSL_NO_EC */
@@ -685,15 +815,7 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
/* Add TLS extension EllipticCurves to the ClientHello message */
plist = s->tlsext_ellipticcurvelist;
/* If we have a custom curve list use it otherwise
* use default */
if (plist)
plistlen = s->tlsext_ellipticcurvelist_length;
else
{
plist = eccurves_default;
plistlen = sizeof(eccurves_default);
}
tls1_get_curvelist(s, 0, &plist, &plistlen);
if ((lenmax = limit - ret - 6) < 0) return NULL;
if (plistlen > (size_t)lenmax) return NULL;