int signature_verify(ssh_session session, ssh_string signature) {
ssh_public_key pubkey = NULL;
SIGNATURE *sign = NULL;
int err;
enter_function();
pubkey = publickey_from_string(session,session->next_crypto->server_pubkey);
if(pubkey == NULL) {
leave_function();
return -1;
}
if (session->wanted_methods[SSH_HOSTKEYS]) {
if(!match(session->wanted_methods[SSH_HOSTKEYS],pubkey->type_c)) {
ssh_set_error(session, SSH_FATAL,
"Public key from server (%s) doesn't match user preference (%s)",
pubkey->type_c, session->wanted_methods[SSH_HOSTKEYS]);
publickey_free(pubkey);
leave_function();
return -1;
}
}
sign = signature_from_string(session, signature, pubkey, pubkey->type);
if (sign == NULL) {
ssh_set_error(session, SSH_FATAL, "Invalid signature blob");
publickey_free(pubkey);
leave_function();
return -1;
}
ssh_log(session, SSH_LOG_FUNCTIONS,
"Going to verify a %s type signature", pubkey->type_c);
err = sig_verify(session,pubkey,sign,
session->next_crypto->session_id,SHA_DIGEST_LEN);
signature_free(sign);
session->next_crypto->server_pubkey_type = pubkey->type_c;
publickey_free(pubkey);
leave_function();
return err;
}
/**
* Do some basic checks on the certificate chain.
*
* Certificate verification consists of a number of checks:
* - The date of the certificate is after the start date.
* - The date of the certificate is before the finish date.
* - A root certificate exists in the certificate store.
* - That the certificate(s) are not self-signed.
* - The certificate chain is valid.
* - The signature of the certificate is valid.
*/
int x509_verify(const CA_CERT_CTX *ca_cert_ctx, const X509_CTX *cert)
{
int ret = X509_OK, i = 0;
bigint *cert_sig;
X509_CTX *next_cert = NULL;
BI_CTX *ctx = NULL;
bigint *mod = NULL, *expn = NULL;
int match_ca_cert = 0;
struct timeval tv;
uint8_t is_self_signed = 0;
if (cert == NULL)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
/* a self-signed certificate that is not in the CA store - use this
to check the signature */
if (asn1_compare_dn(cert->ca_cert_dn, cert->cert_dn) == 0)
{
is_self_signed = 1;
ctx = cert->rsa_ctx->bi_ctx;
mod = cert->rsa_ctx->m;
expn = cert->rsa_ctx->e;
}
gettimeofday(&tv, NULL);
/* check the not before date */
if (tv.tv_sec < cert->not_before)
{
ret = X509_VFY_ERROR_NOT_YET_VALID;
goto end_verify;
}
/* check the not after date */
if (tv.tv_sec > cert->not_after)
{
ret = X509_VFY_ERROR_EXPIRED;
goto end_verify;
}
next_cert = cert->next;
/* last cert in the chain - look for a trusted cert */
if (next_cert == NULL)
{
if (ca_cert_ctx != NULL)
{
/* go thu the CA store */
while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
{
if (asn1_compare_dn(cert->ca_cert_dn,
ca_cert_ctx->cert[i]->cert_dn) == 0)
{
/* use this CA certificate for signature verification */
match_ca_cert = 1;
ctx = ca_cert_ctx->cert[i]->rsa_ctx->bi_ctx;
mod = ca_cert_ctx->cert[i]->rsa_ctx->m;
expn = ca_cert_ctx->cert[i]->rsa_ctx->e;
break;
}
i++;
}
}
/* couldn't find a trusted cert (& let self-signed errors
be returned) */
if (!match_ca_cert && !is_self_signed)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
}
else if (asn1_compare_dn(cert->ca_cert_dn, next_cert->cert_dn) != 0)
{
/* check the chain */
ret = X509_VFY_ERROR_INVALID_CHAIN;
goto end_verify;
}
else /* use the next certificate in the chain for signature verify */
{
ctx = next_cert->rsa_ctx->bi_ctx;
mod = next_cert->rsa_ctx->m;
expn = next_cert->rsa_ctx->e;
}
/* cert is self signed */
if (!match_ca_cert && is_self_signed)
{
ret = X509_VFY_ERROR_SELF_SIGNED;
goto end_verify;
}
/* check the signature */
cert_sig = sig_verify(ctx, cert->signature, cert->sig_len,
bi_clone(ctx, mod), bi_clone(ctx, expn));
if (cert_sig && cert->digest)
{
if (bi_compare(cert_sig, cert->digest) != 0)
ret = X509_VFY_ERROR_BAD_SIGNATURE;
bi_free(ctx, cert_sig);
}
else
{
ret = X509_VFY_ERROR_BAD_SIGNATURE;
}
if (ret)
goto end_verify;
/* go down the certificate chain using recursion. */
if (next_cert != NULL)
{
ret = x509_verify(ca_cert_ctx, next_cert);
}
end_verify:
return ret;
}
/**
* Do some basic checks on the certificate chain.
*
* Certificate verification consists of a number of checks:
* - The date of the certificate is after the start date.
* - The date of the certificate is before the finish date.
* - A root certificate exists in the certificate store.
* - That the certificate(s) are not self-signed.
* - The certificate chain is valid.
* - The signature of the certificate is valid.
*/
int x509_verify(X509_CTX* ca_certs /* GBG: changed */, const X509_CTX *cert, const SSL_DateTime* now)
{
int ret = X509_OK;
bigint *cert_sig;
X509_CTX *next_cert = NULL;
BI_CTX *ctx = NULL;
bigint *mod = NULL, *expn = NULL;
int match_ca_cert = 0;
uint8_t is_self_signed = 0;
SSL_DateTime now_dt;
if (cert == NULL)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
/* a self-signed certificate that is not in the CA store - use this
to check the signature */
if (asn1_compare_dn(cert->ca_cert_dn, cert->cert_dn) == 0)
{
is_self_signed = 1;
ctx = cert->rsa_ctx->bi_ctx;
mod = cert->rsa_ctx->m;
expn = cert->rsa_ctx->e;
}
/* if the time was not passed in, get it now */
if (now == NULL) {
SSL_DateTime_Now(&now_dt);
now = &now_dt;
}
/* check the not before date */
if (SSL_DateTime_Before(now, &cert->not_before))
{
ret = X509_VFY_ERROR_NOT_YET_VALID;
goto end_verify;
}
/* check the not after date */
if (SSL_DateTime_Before(&cert->not_after, now))
{
ret = X509_VFY_ERROR_EXPIRED;
goto end_verify;
}
next_cert = cert->next;
/* last cert in the chain - look for a trusted cert */
if (next_cert == NULL)
{
/* GBG: modified */
X509_CTX* ca_cert = ca_certs;
while (ca_cert) {
if (asn1_compare_dn(cert->ca_cert_dn, ca_cert->cert_dn) == 0) {
/* use this CA certificate for signature verification */
match_ca_cert = 1;
ctx = ca_cert->rsa_ctx->bi_ctx;
mod = ca_cert->rsa_ctx->m;
expn = ca_cert->rsa_ctx->e;
break;
}
ca_cert = ca_cert->next;
}
/* couldn't find a trusted cert (& let self-signed errors be returned) */
if (!match_ca_cert && !is_self_signed)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
}
else if (asn1_compare_dn(cert->ca_cert_dn, next_cert->cert_dn) != 0)
{
/* check the chain */
ret = X509_VFY_ERROR_INVALID_CHAIN;
goto end_verify;
}
else /* use the next certificate in the chain for signature verify */
{
ctx = next_cert->rsa_ctx->bi_ctx;
mod = next_cert->rsa_ctx->m;
expn = next_cert->rsa_ctx->e;
}
/* cert is self signed */
if (!match_ca_cert && is_self_signed)
{
ret = X509_VFY_ERROR_SELF_SIGNED;
goto end_verify;
}
/* check the signature */
cert_sig = sig_verify(ctx, cert->signature, cert->sig_len,
bi_clone(ctx, mod), bi_clone(ctx, expn));
if (cert_sig && cert->digest)
{
if (bi_compare(cert_sig, cert->digest) != 0)
ret = X509_VFY_ERROR_BAD_SIGNATURE;
bi_free(ctx, cert_sig);
}
else
{
ret = X509_VFY_ERROR_BAD_SIGNATURE;
}
if (ret)
goto end_verify;
/* go down the certificate chain using recursion. */
if (next_cert != NULL)
{
ret = x509_verify(ca_certs, next_cert, now);
}
end_verify:
return ret;
}
/**
* Do some basic checks on the certificate chain.
*
* Certificate verification consists of a number of checks:
* - The date of the certificate is after the start date.
* - The date of the certificate is before the finish date.
* - A root certificate exists in the certificate store.
* - That the certificate(s) are not self-signed.
* - The certificate chain is valid.
* - The signature of the certificate is valid.
* - Basic constraints
*/
int x509_verify(const CA_CERT_CTX *ca_cert_ctx, const X509_CTX *cert,
int *pathLenConstraint)
{
int ret = X509_OK, i = 0;
bigint *cert_sig;
X509_CTX *next_cert = NULL;
BI_CTX *ctx = NULL;
bigint *mod = NULL, *expn = NULL;
int match_ca_cert = 0;
struct timeval tv;
uint8_t is_self_signed = 0;
if (cert == NULL)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
/* a self-signed certificate that is not in the CA store - use this
to check the signature */
if (asn1_compare_dn(cert->ca_cert_dn, cert->cert_dn) == 0)
{
is_self_signed = 1;
ctx = cert->rsa_ctx->bi_ctx;
mod = cert->rsa_ctx->m;
expn = cert->rsa_ctx->e;
}
gettimeofday(&tv, NULL);
/* check the not before date */
if (tv.tv_sec < cert->not_before)
{
ret = X509_VFY_ERROR_NOT_YET_VALID;
goto end_verify;
}
/* check the not after date */
if (tv.tv_sec > cert->not_after)
{
ret = X509_VFY_ERROR_EXPIRED;
goto end_verify;
}
if (cert->basic_constraint_present)
{
/* If the cA boolean is not asserted,
then the keyCertSign bit in the key usage extension MUST NOT be
asserted. */
if (!cert->basic_constraint_cA &&
IS_SET_KEY_USAGE_FLAG(cert, KEY_USAGE_KEY_CERT_SIGN))
{
ret = X509_VFY_ERROR_BASIC_CONSTRAINT;
goto end_verify;
}
/* The pathLenConstraint field is meaningful only if the cA boolean is
asserted and the key usage extension, if present, asserts the
keyCertSign bit. In this case, it gives the maximum number of
non-self-issued intermediate certificates that may follow this
certificate in a valid certification path. */
if (cert->basic_constraint_cA &&
(!cert->key_usage_present ||
IS_SET_KEY_USAGE_FLAG(cert, KEY_USAGE_KEY_CERT_SIGN)) &&
(cert->basic_constraint_pathLenConstraint+1) < *pathLenConstraint)
{
ret = X509_VFY_ERROR_BASIC_CONSTRAINT;
goto end_verify;
}
}
next_cert = cert->next;
/* last cert in the chain - look for a trusted cert */
if (next_cert == NULL)
{
if (ca_cert_ctx != NULL)
{
/* go thru the CA store */
while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
{
/* the extension is present but the cA boolean is not
asserted, then the certified public key MUST NOT be used
to verify certificate signatures. */
if (cert->basic_constraint_present &&
!ca_cert_ctx->cert[i]->basic_constraint_cA)
continue;
if (asn1_compare_dn(cert->ca_cert_dn,
ca_cert_ctx->cert[i]->cert_dn) == 0)
{
/* use this CA certificate for signature verification */
match_ca_cert = true;
ctx = ca_cert_ctx->cert[i]->rsa_ctx->bi_ctx;
mod = ca_cert_ctx->cert[i]->rsa_ctx->m;
expn = ca_cert_ctx->cert[i]->rsa_ctx->e;
break;
}
i++;
}
}
/* couldn't find a trusted cert (& let self-signed errors
be returned) */
if (!match_ca_cert && !is_self_signed)
{
ret = X509_VFY_ERROR_NO_TRUSTED_CERT;
goto end_verify;
}
}
else if (asn1_compare_dn(cert->ca_cert_dn, next_cert->cert_dn) != 0)
{
/* check the chain */
ret = X509_VFY_ERROR_INVALID_CHAIN;
goto end_verify;
}
else /* use the next certificate in the chain for signature verify */
{
ctx = next_cert->rsa_ctx->bi_ctx;
mod = next_cert->rsa_ctx->m;
expn = next_cert->rsa_ctx->e;
}
/* cert is self signed */
if (!match_ca_cert && is_self_signed)
{
ret = X509_VFY_ERROR_SELF_SIGNED;
goto end_verify;
}
/* check the signature */
cert_sig = sig_verify(ctx, cert->signature, cert->sig_len,
bi_clone(ctx, mod), bi_clone(ctx, expn));
if (cert_sig && cert->digest)
{
if (bi_compare(cert_sig, cert->digest) != 0)
ret = X509_VFY_ERROR_BAD_SIGNATURE;
bi_free(ctx, cert_sig);
}
else
{
ret = X509_VFY_ERROR_BAD_SIGNATURE;
}
bi_clear_cache(ctx);
if (ret)
goto end_verify;
/* go down the certificate chain using recursion. */
if (next_cert != NULL)
{
(*pathLenConstraint)++; /* don't include last certificate */
ret = x509_verify(ca_cert_ctx, next_cert, pathLenConstraint);
}
end_verify:
return ret;
}
