make ssl certificate handling much more useful:

- system-wide ca certs are auto-loaded
- private certs are accepted even if they are self-signed
This commit is contained in:
Oswald Buddenhagen 2008-04-13 09:51:27 +00:00
parent 06521da30d
commit 262999d092

View File

@ -66,6 +66,7 @@ typedef struct imap_server_conf {
unsigned use_sslv3:1; unsigned use_sslv3:1;
unsigned use_tlsv1:1; unsigned use_tlsv1:1;
unsigned require_cram:1; unsigned require_cram:1;
X509_STORE *cert_store;
#endif #endif
} imap_server_conf_t; } imap_server_conf_t;
@ -182,15 +183,46 @@ static const char *Flags[] = {
}; };
#if HAVE_LIBSSL #if HAVE_LIBSSL
/* Some of this code is inspired by / lifted from mutt. */
static int
compare_certificates( X509 *cert, X509 *peercert,
unsigned char *peermd, unsigned peermdlen )
{
unsigned char md[EVP_MAX_MD_SIZE];
unsigned mdlen;
/* Avoid CPU-intensive digest calculation if the certificates are
* not even remotely equal. */
if (X509_subject_name_cmp( cert, peercert ) ||
X509_issuer_name_cmp( cert, peercert ))
return -1;
if (!X509_digest( cert, EVP_sha1(), md, &mdlen ) ||
peermdlen != mdlen || memcmp( peermd, md, mdlen ))
return -1;
return 0;
}
#if OPENSSL_VERSION_NUMBER >= 0x00904000L
#define READ_X509_KEY(fp, key) PEM_read_X509( fp, key, 0, 0 )
#else
#define READ_X509_KEY(fp, key) PEM_read_X509( fp, key, 0 )
#endif
/* this gets called when a certificate is to be verified */ /* this gets called when a certificate is to be verified */
static int static int
verify_cert( SSL *ssl ) verify_cert( imap_store_t *ctx )
{ {
X509 *cert; imap_server_conf_t *srvc = ((imap_store_conf_t *)ctx->gen.conf)->server;
SSL *ssl = ctx->buf.sock.ssl;
X509 *cert, *lcert;
BIO *bio; BIO *bio;
FILE *fp;
int err; int err;
unsigned n, i; unsigned n, i;
X509_STORE_CTX xsc;
char buf[256]; char buf[256];
unsigned char md[EVP_MAX_MD_SIZE]; unsigned char md[EVP_MAX_MD_SIZE];
@ -200,10 +232,56 @@ verify_cert( SSL *ssl )
return -1; return -1;
} }
err = SSL_get_verify_result( ssl ); while (srvc->cert_file) { // So break works
if (err == X509_V_OK) if (X509_cmp_current_time( X509_get_notBefore( cert )) >= 0) {
error( "Server certificate is not yet valid" );
break;
}
if (X509_cmp_current_time( X509_get_notAfter( cert )) <= 0) {
error( "Server certificate has expired" );
break;
}
if (!X509_digest( cert, EVP_sha1(), md, &n )) {
error( "*** Unable to calculate digest\n" );
break;
}
if (!(fp = fopen( srvc->cert_file, "rt" ))) {
error( "Unable to load CertificateFile '%s': %s\n",
srvc->cert_file, strerror( errno ) );
return 0; return 0;
}
for (lcert = 0; READ_X509_KEY( fp, &lcert ); )
if (!(err = compare_certificates( lcert, cert, md, n )))
break;
X509_free( lcert );
fclose( fp );
if (!err)
return 0;
break;
}
if (!srvc->cert_store) {
if (!(srvc->cert_store = X509_STORE_new())) {
error( "Error creating certificate store\n" );
return -1;
}
if (!X509_STORE_set_default_paths( srvc->cert_store ))
warn( "Error while loading default certificate files: %s\n",
ERR_error_string( ERR_get_error(), 0 ) );
if (!srvc->cert_file) {
info( "Note: CertificateFile not defined\n" );
} else if (!X509_STORE_load_locations( srvc->cert_store, srvc->cert_file, 0 )) {
error( "Error while loading certificate file '%s': %s\n",
srvc->cert_file, ERR_error_string( ERR_get_error(), 0 ) );
return -1;
}
}
X509_STORE_CTX_init( &xsc, srvc->cert_store, cert, 0 );
err = X509_verify_cert( &xsc ) > 0 ? 0 : X509_STORE_CTX_get_error( &xsc );
X509_STORE_CTX_cleanup( &xsc );
if (!err)
return 0;
error( "Error, can't verify certificate: %s (%d)\n", error( "Error, can't verify certificate: %s (%d)\n",
X509_verify_cert_error_string( err ), err ); X509_verify_cert_error_string( err ), err );
@ -221,9 +299,9 @@ verify_cert( SSL *ssl )
BIO_read( bio, buf, sizeof(buf) - 1 ); BIO_read( bio, buf, sizeof(buf) - 1 );
BIO_free( bio ); BIO_free( bio );
info( " to: %s\n", buf ); info( " to: %s\n", buf );
if (!X509_digest( cert, EVP_md5(), md, &n )) if (!X509_digest( cert, EVP_md5(), md, &n )) {
info( "*** Unable to calculate fingerprint\n" ); error( "*** Unable to calculate fingerprint\n" );
else { } else {
info( "Fingerprint: " ); info( "Fingerprint: " );
for (i = 0; i < n; i += 2) for (i = 0; i < n; i += 2)
info( "%02X%02X ", md[i], md[i + 1] ); info( "%02X%02X ", md[i], md[i + 1] );
@ -249,14 +327,6 @@ init_ssl_ctx( imap_store_t *ctx )
method = SSLv23_client_method(); method = SSLv23_client_method();
ctx->SSLContext = SSL_CTX_new( method ); ctx->SSLContext = SSL_CTX_new( method );
if (!srvc->cert_file) {
info( "Note: CertificateFile not defined\n" );
} else if (!SSL_CTX_load_verify_locations( ctx->SSLContext, srvc->cert_file, NULL )) {
error( "Error while loading certificate file '%s': %s\n",
srvc->cert_file, ERR_error_string( ERR_get_error(), 0 ) );
return -1;
}
if (!srvc->use_sslv2) if (!srvc->use_sslv2)
options |= SSL_OP_NO_SSLv2; options |= SSL_OP_NO_SSLv2;
if (!srvc->use_sslv3) if (!srvc->use_sslv3)
@ -1121,7 +1191,7 @@ start_tls( imap_store_t *ctx )
} }
/* verify the server certificate */ /* verify the server certificate */
if (verify_cert( ctx->buf.sock.ssl )) if (verify_cert( ctx ))
return 1; return 1;
ctx->buf.sock.use_ssl = 1; ctx->buf.sock.use_ssl = 1;