Internal changes to allow for relayd engine privsep. sends the hash of the

public key as an identifier to RSA, and adds an function for relayd to
use to disable private key checking when doing engine privsep.
ok jsing@

5 files changed, 87 insertions, 29 deletions

diff --git a/src/lib/libtls/Symbols.list b/src/lib/libtls/Symbols.list
index eb704ecbd2..98465dde27 100644
--- a/src/lib/libtls/Symbols.list
+++ b/src/lib/libtls/Symbols.list
@@ -40,6 +40,7 @@ tls_config_set_protocols
 tls_config_set_session_id
 tls_config_set_session_lifetime
 tls_config_set_verify_depth
+tls_config_skip_private_key_check
 tls_config_verify
 tls_config_verify_client
 tls_config_verify_client_optional
diff --git a/src/lib/libtls/tls.c b/src/lib/libtls/tls.c
index 9b03c2b6f0..419554818c 100644
--- a/src/lib/libtls/tls.c
+++ b/src/lib/libtls/tls.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls.c,v 1.59 2017/01/26 12:56:37 jsing Exp $ */
+/* $OpenBSD: tls.c,v 1.60 2017/04/05 03:13:53 beck Exp $ */
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
  *
@@ -252,6 +252,55 @@ tls_configure(struct tls *ctx, struct tls_config *config)
 }
 
 int
+tls_cert_hash(X509 *cert, char **hash)
+{
+        char d[EVP_MAX_MD_SIZE], *dhex = NULL;
+        int dlen, rv = -1;
+
+        *hash = NULL;
+        if (X509_digest(cert, EVP_sha256(), d, &dlen) != 1)
+                goto err;
+
+        if (tls_hex_string(d, dlen, &dhex, NULL) != 0)
+                goto err;
+
+        if (asprintf(hash, "SHA256:%s", dhex) == -1) {
+                *hash = NULL;
+                goto err;
+        }
+
+        rv = 0;
+ err:
+        free(dhex);
+
+        return (rv);
+}
+
+static int
+tls_keypair_cert_hash(struct tls_keypair *keypair, char **hash)
+{
+        BIO *membio = NULL;
+        X509 *cert = NULL;
+        int rv = -1;
+
+        *hash = NULL;
+
+        if ((membio = BIO_new_mem_buf(keypair->cert_mem, keypair->cert_len))
+            == NULL)
+                goto err;
+
+        if ((cert = PEM_read_bio_X509_AUX(membio, NULL, NULL, NULL)) == NULL)
+                goto err;
+
+        rv = tls_cert_hash(cert, hash);
+ err:
+        BIO_free(membio);
+
+        return (rv);
+}
+
+
+int
 tls_configure_ssl_keypair(struct tls *ctx, SSL_CTX *ssl_ctx,
     struct tls_keypair *keypair, int required)
 {
@@ -275,8 +324,11 @@ tls_configure_ssl_keypair(struct tls *ctx, SSL_CTX *ssl_ctx,
                         tls_set_errorx(ctx, "failed to load certificate");
                         goto err;
                 }
+                if (tls_keypair_cert_hash(keypair, &keypair->cert_hash) == -1)
+                        goto err;
                 cert = NULL;
         }
+
         if (keypair->key_mem != NULL) {
                 if (keypair->key_len > INT_MAX) {
                         tls_set_errorx(ctx, "key too long");
@@ -293,6 +345,16 @@ tls_configure_ssl_keypair(struct tls *ctx, SSL_CTX *ssl_ctx,
                         tls_set_errorx(ctx, "failed to read private key");
                         goto err;
                 }
+
+                if (keypair->cert_hash != NULL) {
+                        RSA *rsa;
+                        /* XXX only RSA for now for relayd privsep */
+                        if ((rsa = EVP_PKEY_get1_RSA(pkey)) != NULL) {
+                                RSA_set_ex_data(rsa, 0, keypair->cert_hash);
+                                RSA_free(rsa);
+                        }
+                }
+
                 if (SSL_CTX_use_PrivateKey(ssl_ctx, pkey) != 1) {
                         tls_set_errorx(ctx, "failed to load private key");
                         goto err;
@@ -303,7 +365,8 @@ tls_configure_ssl_keypair(struct tls *ctx, SSL_CTX *ssl_ctx,
                 pkey = NULL;
         }
 
-        if (SSL_CTX_check_private_key(ssl_ctx) != 1) {
+        if (!ctx->config->skip_private_key_check &&
+            SSL_CTX_check_private_key(ssl_ctx) != 1) {
                 tls_set_errorx(ctx, "private/public key mismatch");
                 goto err;
         }
diff --git a/src/lib/libtls/tls_config.c b/src/lib/libtls/tls_config.c
index 87c2166f9e..f5e0bf55e4 100644
--- a/src/lib/libtls/tls_config.c
+++ b/src/lib/libtls/tls_config.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls_config.c,v 1.36 2017/01/31 16:18:57 beck Exp $ */
+/* $OpenBSD: tls_config.c,v 1.37 2017/04/05 03:13:53 beck Exp $ */
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
  *
@@ -135,6 +135,7 @@ tls_keypair_free(struct tls_keypair *keypair)
         free(keypair->cert_mem);
         free(keypair->key_mem);
         free(keypair->ocsp_staple);
+        free(keypair->cert_hash);
 
         free(keypair);
 }
@@ -761,6 +762,12 @@ tls_config_verify_client_optional(struct tls_config *config)
         config->verify_client = 2;
 }
 
+void
+tls_config_skip_private_key_check(struct tls_config *config)
+{
+        config->skip_private_key_check = 1;
+}
+
 int
 tls_config_set_ocsp_staple_file(struct tls_config *config, const char *staple_file)
 {
diff --git a/src/lib/libtls/tls_conninfo.c b/src/lib/libtls/tls_conninfo.c
index 5cdd0f77c8..c4d23c308b 100644
--- a/src/lib/libtls/tls_conninfo.c
+++ b/src/lib/libtls/tls_conninfo.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls_conninfo.c,v 1.13 2017/01/09 15:31:20 jsing Exp $ */
+/* $OpenBSD: tls_conninfo.c,v 1.14 2017/04/05 03:13:53 beck Exp $ */
 /*
  * Copyright (c) 2015 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2015 Bob Beck <beck@openbsd.org>
@@ -23,7 +23,7 @@
 #include <tls.h>
 #include "tls_internal.h"
 
-static int
+int
 tls_hex_string(const unsigned char *in, size_t inlen, char **out,
     size_t *outlen)
 {
@@ -56,35 +56,16 @@ tls_hex_string(const unsigned char *in, size_t inlen, char **out,
 static int
 tls_get_peer_cert_hash(struct tls *ctx, char **hash)
 {
-        char d[EVP_MAX_MD_SIZE], *dhex = NULL;
-        int dlen, rv = -1;
-
         *hash = NULL;
         if (ctx->ssl_peer_cert == NULL)
                 return (0);
 
-        if (X509_digest(ctx->ssl_peer_cert, EVP_sha256(), d, &dlen) != 1) {
-                tls_set_errorx(ctx, "digest failed");
-                goto err;
-        }
-
-        if (tls_hex_string(d, dlen, &dhex, NULL) != 0) {
-                tls_set_errorx(ctx, "digest hex string failed");
-                goto err;
-        }
-
-        if (asprintf(hash, "SHA256:%s", dhex) == -1) {
-                tls_set_errorx(ctx, "out of memory");
+        if (tls_cert_hash(ctx->ssl_peer_cert, hash) == -1) {
+                tls_set_errorx(ctx, "unable to compute peer certificate hash - out of memory");
                 *hash = NULL;
-                goto err;
+                return -1;
         }
-
-        rv = 0;
-
-err:
-        free(dhex);
-
-        return (rv);
+        return 0;
 }
 
 static int
@@ -294,3 +275,4 @@ tls_conn_version(struct tls *ctx)
                 return (NULL);
         return (ctx->conninfo->version);
 }
+
diff --git a/src/lib/libtls/tls_internal.h b/src/lib/libtls/tls_internal.h
index fbb139c84a..b1d53c8fa3 100644
--- a/src/lib/libtls/tls_internal.h
+++ b/src/lib/libtls/tls_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls_internal.h,v 1.53 2017/01/29 17:52:11 beck Exp $ */
+/* $OpenBSD: tls_internal.h,v 1.54 2017/04/05 03:13:53 beck Exp $ */
 /*
  * Copyright (c) 2014 Jeremie Courreges-Anglas <jca@openbsd.org>
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
@@ -53,6 +53,7 @@ struct tls_keypair {
         size_t key_len;
         char *ocsp_staple;
         size_t ocsp_staple_len;
+        char *cert_hash;
 };
 
 #define TLS_MIN_SESSION_TIMEOUT (4)
@@ -96,6 +97,7 @@ struct tls_config {
         int verify_depth;
         int verify_name;
         int verify_time;
+        int skip_private_key_check;
 };
 
 struct tls_conninfo {
@@ -232,6 +234,9 @@ int tls_ocsp_verify_cb(SSL *ssl, void *arg);
 int tls_ocsp_stapling_cb(SSL *ssl, void *arg);
 void tls_ocsp_free(struct tls_ocsp *ctx);
 struct tls_ocsp *tls_ocsp_setup_from_peer(struct tls *ctx);
+int tls_hex_string(const unsigned char *_in, size_t _inlen, char **_out,
+    size_t *_outlen);
+int tls_cert_hash(X509 *_cert, char **_hash);
 
 __END_HIDDEN_DECLS