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Add function tls_choose_sigalg(). 

New function tls_choose_sigalg(). This is a signature algorithm version
of ssl3_choose_cipher(): it picks and sets the appropriate signature
algorithm and certificate based on shared signature algorithms.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2339)
This commit is contained in:
Dr. Stephen Henson 2017-01-31 17:45:00 +00:00
parent 3f4bf115a1
commit 93a77f9e2c
2 changed files with 63 additions and 0 deletions
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6
ssl/ssl_locl.h
View File

@ -1287,6 +1287,10 @@ typedef struct ssl3_state_st {
unsigned char *psk;
size_t psklen;
# endif
/* Signature algorithm we actually use */
const SIGALG_LOOKUP *sigalg;
/* Index of certificate we use */
int cert_idx;
/*
* signature algorithms peer reports: e.g. supported signature
* algorithms extension for server or as part of a certificate
@ -2257,6 +2261,8 @@ __owur int ssl_security_cert(SSL *s, SSL_CTX *ctx, X509 *x, int vfy, int is_ee);
__owur int ssl_security_cert_chain(SSL *s, STACK_OF(X509) *sk, X509 *ex,
int vfy);
int tls_choose_sigalg(SSL *s);
__owur EVP_MD_CTX *ssl_replace_hash(EVP_MD_CTX **hash, const EVP_MD *md);
void ssl_clear_hash_ctx(EVP_MD_CTX **hash);
__owur long ssl_get_algorithm2(SSL *s);

57
ssl/t1_lib.c
View File

@ -2270,3 +2270,60 @@ int ssl_security_cert_chain(SSL *s, STACK_OF(X509) *sk, X509 *x, int vfy)
}
return 1;
}
/*
* Choose an appropriate signature algorithm based on available certificates
* Set current certificate and digest to match chosen algorithm.
*/
int tls_choose_sigalg(SSL *s)
{
if (SSL_IS_TLS13(s)) {
size_t i;
int curve = -1;
/* Look for a certificate matching shared sigaglgs */
for (i = 0; i < s->cert->shared_sigalgslen; i++) {
const SIGALG_LOOKUP *lu = s->cert->shared_sigalgs[i];
int idx;
const EVP_MD *md;
CERT_PKEY *c;
/* Skip RSA if not PSS */
if (lu->sig == EVP_PKEY_RSA)
continue;
md = ssl_md(lu->hash_idx);
if (md == NULL)
continue;
idx = lu->sig_idx;
c = &s->cert->pkeys[idx];
if (c->x509 == NULL || c->privatekey == NULL) {
if (idx != SSL_PKEY_RSA_SIGN)
continue;
idx = SSL_PKEY_RSA_ENC;
c = s->cert->pkeys + idx;
if (c->x509 == NULL || c->privatekey == NULL)
continue;
}
if (lu->sig == EVP_PKEY_EC) {
if (curve == -1) {
EC_KEY *ec = EVP_PKEY_get0_EC_KEY(c->privatekey);
curve = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
}
if (curve != lu->curve)
continue;
}
s->s3->tmp.sigalg = lu;
s->s3->tmp.cert_idx = idx;
s->s3->tmp.md[idx] = md;
s->cert->key = s->cert->pkeys + idx;
return 1;
}
return 0;
}
/*
* FIXME: could handle previous TLS versions in an appropriate way
* and tidy up certificate and signature algorithm handling.
*/
return 1;
}