BOOL tls_verify_certificate(rdpTls* tls, CryptoCert cert, char* hostname)
{
int match;
int index;
char* common_name = NULL;
int common_name_length = 0;
char** alt_names = NULL;
int alt_names_count = 0;
int* alt_names_lengths = NULL;
BOOL certificate_status;
BOOL hostname_match = FALSE;
BOOL verification_status = FALSE;
rdpCertificateData* certificate_data;
/* ignore certificate verification if user explicitly required it (discouraged) */
if (tls->settings->IgnoreCertificate)
return TRUE; /* success! */
/* if user explicitly specified a certificate name, use it instead of the hostname */
if (tls->settings->CertificateName)
hostname = tls->settings->CertificateName;
/* attempt verification using OpenSSL and the ~/.freerdp/certs certificate store */
certificate_status = x509_verify_certificate(cert, tls->certificate_store->path);
/* verify certificate name match */
certificate_data = crypto_get_certificate_data(cert->px509, hostname);
/* extra common name and alternative names */
common_name = crypto_cert_subject_common_name(cert->px509, &common_name_length);
alt_names = crypto_cert_subject_alt_name(cert->px509, &alt_names_count, &alt_names_lengths);
/* compare against common name */
if (common_name != NULL)
{
if (strlen(hostname) == common_name_length)
{
if (memcmp((void*) hostname, (void*) common_name, common_name_length) == 0)
hostname_match = TRUE;
}
}
/* compare against alternative names */
if (alt_names != NULL)
{
for (index = 0; index < alt_names_count; index++)
{
if (strlen(hostname) == alt_names_lengths[index])
{
if (memcmp((void*) hostname, (void*) alt_names[index], alt_names_lengths[index]) == 0)
hostname_match = TRUE;
}
}
}
/* if the certificate is valid and the certificate name matches, verification succeeds */
if (certificate_status && hostname_match)
{
if (common_name)
{
free(common_name);
common_name = NULL;
}
verification_status = TRUE; /* success! */
}
/* if the certificate is valid but the certificate name does not match, warn user, do not accept */
if (certificate_status && !hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
/* verification could not succeed with OpenSSL, use known_hosts file and prompt user for manual verification */
if (!certificate_status)
{
char* issuer;
char* subject;
char* fingerprint;
freerdp* instance = (freerdp*) tls->settings->instance;
BOOL accept_certificate = FALSE;
issuer = crypto_cert_issuer(cert->px509);
subject = crypto_cert_subject(cert->px509);
fingerprint = crypto_cert_fingerprint(cert->px509);
/* search for matching entry in known_hosts file */
match = certificate_data_match(tls->certificate_store, certificate_data);
if (match == 1)
{
/* no entry was found in known_hosts file, prompt user for manual verification */
if (!hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
if (instance->VerifyCertificate)
accept_certificate = instance->VerifyCertificate(instance, subject, issuer, fingerprint);
if (!accept_certificate)
{
/* user did not accept, abort and do not add entry in known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted certificate, add entry in known_hosts file */
certificate_data_print(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
}
else if (match == -1)
{
/* entry was found in known_hosts file, but fingerprint does not match. ask user to use it */
tls_print_certificate_error(hostname, fingerprint, tls->certificate_store->file);
if (instance->VerifyChangedCertificate)
accept_certificate = instance->VerifyChangedCertificate(instance, subject, issuer, fingerprint, "");
if (!accept_certificate)
{
/* user did not accept, abort and do not change known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted new certificate, add replace fingerprint for this host in known_hosts file */
certificate_data_replace(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
}
else if (match == 0)
{
verification_status = TRUE; /* success! */
}
free(issuer);
free(subject);
free(fingerprint);
}
if (certificate_data)
{
free(certificate_data->fingerprint);
free(certificate_data->hostname);
free(certificate_data);
}
#ifndef _WIN32
free(common_name);
#endif
return verification_status;
}
int tls_verify_certificate(rdpTls* tls, CryptoCert cert, char* hostname, int port)
{
int match;
int index;
char* common_name = NULL;
int common_name_length = 0;
char** alt_names = NULL;
int alt_names_count = 0;
int* alt_names_lengths = NULL;
BOOL certificate_status;
BOOL hostname_match = FALSE;
BOOL verification_status = FALSE;
rdpCertificateData* certificate_data;
if (tls->settings->ExternalCertificateManagement)
{
BIO* bio;
int status;
int length;
int offset;
BYTE* pemCert;
freerdp* instance = (freerdp*) tls->settings->instance;
/**
* Don't manage certificates internally, leave it up entirely to the external client implementation
*/
bio = BIO_new(BIO_s_mem());
if (!bio)
{
fprintf(stderr, "%s: BIO_new() failure\n", __FUNCTION__);
return -1;
}
status = PEM_write_bio_X509(bio, cert->px509);
if (status < 0)
{
fprintf(stderr, "%s: PEM_write_bio_X509 failure: %d\n", __FUNCTION__, status);
return -1;
}
offset = 0;
length = 2048;
pemCert = (BYTE*) malloc(length + 1);
status = BIO_read(bio, pemCert, length);
if (status < 0)
{
fprintf(stderr, "%s: failed to read certificate\n", __FUNCTION__);
return -1;
}
offset += status;
while (offset >= length)
{
length *= 2;
pemCert = (BYTE*) realloc(pemCert, length + 1);
status = BIO_read(bio, &pemCert[offset], length);
if (status < 0)
break;
offset += status;
}
if (status < 0)
{
fprintf(stderr, "%s: failed to read certificate\n", __FUNCTION__);
return -1;
}
length = offset;
pemCert[length] = '\0';
status = -1;
if (instance->VerifyX509Certificate)
{
status = instance->VerifyX509Certificate(instance, pemCert, length, hostname, port, tls->isGatewayTransport);
}
fprintf(stderr, "%s: (length = %d) status: %d\n%s\n", __FUNCTION__, length, status, pemCert);
free(pemCert);
BIO_free(bio);
if (status < 0)
return -1;
return (status == 0) ? 0 : 1;
}
/* ignore certificate verification if user explicitly required it (discouraged) */
if (tls->settings->IgnoreCertificate)
return 1; /* success! */
/* if user explicitly specified a certificate name, use it instead of the hostname */
if (tls->settings->CertificateName)
hostname = tls->settings->CertificateName;
/* attempt verification using OpenSSL and the ~/.freerdp/certs certificate store */
certificate_status = x509_verify_certificate(cert, tls->certificate_store->path);
/* verify certificate name match */
certificate_data = crypto_get_certificate_data(cert->px509, hostname);
/* extra common name and alternative names */
common_name = crypto_cert_subject_common_name(cert->px509, &common_name_length);
alt_names = crypto_cert_subject_alt_name(cert->px509, &alt_names_count, &alt_names_lengths);
/* compare against common name */
if (common_name)
{
if (tls_match_hostname(common_name, common_name_length, hostname))
hostname_match = TRUE;
}
/* compare against alternative names */
if (alt_names)
{
for (index = 0; index < alt_names_count; index++)
{
if (tls_match_hostname(alt_names[index], alt_names_lengths[index], hostname))
{
hostname_match = TRUE;
break;
}
}
}
/* if the certificate is valid and the certificate name matches, verification succeeds */
if (certificate_status && hostname_match)
{
if (common_name)
{
free(common_name);
common_name = NULL;
}
verification_status = TRUE; /* success! */
}
/* if the certificate is valid but the certificate name does not match, warn user, do not accept */
if (certificate_status && !hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
/* verification could not succeed with OpenSSL, use known_hosts file and prompt user for manual verification */
if (!certificate_status)
{
char* issuer;
char* subject;
char* fingerprint;
freerdp* instance = (freerdp*) tls->settings->instance;
BOOL accept_certificate = FALSE;
issuer = crypto_cert_issuer(cert->px509);
subject = crypto_cert_subject(cert->px509);
fingerprint = crypto_cert_fingerprint(cert->px509);
/* search for matching entry in known_hosts file */
match = certificate_data_match(tls->certificate_store, certificate_data);
if (match == 1)
{
/* no entry was found in known_hosts file, prompt user for manual verification */
if (!hostname_match)
tls_print_certificate_name_mismatch_error(hostname, common_name, alt_names, alt_names_count);
if (instance->VerifyCertificate)
{
accept_certificate = instance->VerifyCertificate(instance, subject, issuer, fingerprint);
}
if (!accept_certificate)
{
/* user did not accept, abort and do not add entry in known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted certificate, add entry in known_hosts file */
certificate_data_print(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
}
else if (match == -1)
{
/* entry was found in known_hosts file, but fingerprint does not match. ask user to use it */
tls_print_certificate_error(hostname, fingerprint, tls->certificate_store->file);
if (instance->VerifyChangedCertificate)
{
accept_certificate = instance->VerifyChangedCertificate(instance, subject, issuer, fingerprint, "");
}
if (!accept_certificate)
{
/* user did not accept, abort and do not change known_hosts file */
verification_status = FALSE; /* failure! */
}
else
{
/* user accepted new certificate, add replace fingerprint for this host in known_hosts file */
certificate_data_replace(tls->certificate_store, certificate_data);
verification_status = TRUE; /* success! */
}
}
else if (match == 0)
{
verification_status = TRUE; /* success! */
}
free(issuer);
free(subject);
free(fingerprint);
}
if (certificate_data)
{
free(certificate_data->fingerprint);
free(certificate_data->hostname);
free(certificate_data);
}
#ifndef _WIN32
if (common_name)
free(common_name);
#endif
if (alt_names)
crypto_cert_subject_alt_name_free(alt_names_count, alt_names_lengths,
alt_names);
return (verification_status == 0) ? 0 : 1;
}
