4 files changed, 33 insertions, 15 deletions

diff --git a/src/lib/libssl/ssl_sigalgs.c b/src/lib/libssl/ssl_sigalgs.c
index bd896c829b..28d1d36b85 100644
--- a/src/lib/libssl/ssl_sigalgs.c
+++ b/src/lib/libssl/ssl_sigalgs.c
@@ -1,6 +1,7 @@
-/* $OpenBSD: ssl_sigalgs.c,v 1.32 2021/06/29 19:10:08 jsing Exp $ */
+/* $OpenBSD: ssl_sigalgs.c,v 1.33 2021/06/29 19:20:39 jsing Exp $ */
 /*
  * Copyright (c) 2018-2020 Bob Beck <beck@openbsd.org>
+ * Copyright (c) 2021 Joel Sing <jsing@openbsd.org>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -14,6 +15,7 @@
  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
+
 #include <string.h>
 #include <stdlib.h>
 
@@ -326,7 +328,6 @@ ssl_sigalg_select(SSL *s, EVP_PKEY *pkey)
                 if ((sigalg = ssl_sigalg_from_value(
                     S3I(s)->hs.negotiated_tls_version, sigalg_value)) == NULL)
                         continue;
-
                 if (ssl_sigalg_pkey_ok(s, sigalg, pkey))
                         return sigalg;
         }
@@ -334,3 +335,24 @@ ssl_sigalg_select(SSL *s, EVP_PKEY *pkey)
         SSLerror(s, SSL_R_UNKNOWN_PKEY_TYPE);
         return NULL;
 }
+
+const struct ssl_sigalg *
+ssl_sigalg_for_peer(SSL *s, EVP_PKEY *pkey, uint16_t sigalg_value)
+{
+        const struct ssl_sigalg *sigalg;
+
+        if (!SSL_USE_SIGALGS(s))
+                return ssl_sigalg_for_legacy(s, pkey);
+
+        if ((sigalg = ssl_sigalg_from_value(S3I(s)->hs.negotiated_tls_version,
+            sigalg_value)) == NULL) {
+                SSLerror(s, SSL_R_UNKNOWN_DIGEST);
+                return (NULL);
+        }
+        if (!ssl_sigalg_pkey_ok(s, sigalg, pkey)) {
+                SSLerror(s, SSL_R_WRONG_SIGNATURE_TYPE);
+                return (NULL);
+        }
+
+        return sigalg;
+}
diff --git a/src/lib/libssl/ssl_sigalgs.h b/src/lib/libssl/ssl_sigalgs.h
index 6905bba060..dffa0e0158 100644
--- a/src/lib/libssl/ssl_sigalgs.h
+++ b/src/lib/libssl/ssl_sigalgs.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_sigalgs.h,v 1.21 2021/06/29 19:10:08 jsing Exp $ */
+/* $OpenBSD: ssl_sigalgs.h,v 1.22 2021/06/29 19:20:39 jsing Exp $ */
 /*
  * Copyright (c) 2018-2019 Bob Beck <beck@openbsd.org>
  *
@@ -75,6 +75,8 @@ int ssl_sigalgs_build(uint16_t tls_version, CBB *cbb);
 int ssl_sigalg_pkey_ok(SSL *s, const struct ssl_sigalg *sigalg,
     EVP_PKEY *pkey);
 const struct ssl_sigalg *ssl_sigalg_select(SSL *s, EVP_PKEY *pkey);
+const struct ssl_sigalg *ssl_sigalg_for_peer(SSL *s, EVP_PKEY *pkey,
+    uint16_t sigalg_value);
 
 __END_HIDDEN_DECLS
 
diff --git a/src/lib/libssl/tls13_client.c b/src/lib/libssl/tls13_client.c
index dd9a5b1606..62c5174490 100644
--- a/src/lib/libssl/tls13_client.c
+++ b/src/lib/libssl/tls13_client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_client.c,v 1.85 2021/06/29 19:10:08 jsing Exp $ */
+/* $OpenBSD: tls13_client.c,v 1.86 2021/06/29 19:20:39 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -680,10 +680,6 @@ tls13_server_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs)
         if (!CBS_get_u16_length_prefixed(cbs, &signature))
                 goto err;
 
-        if ((sigalg = ssl_sigalg_from_value(ctx->hs->negotiated_tls_version,
-            signature_scheme)) == NULL)
-                goto err;
-
         if (!CBB_init(&cbb, 0))
                 goto err;
         if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad,
@@ -704,7 +700,8 @@ tls13_server_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs)
                 goto err;
         if ((pkey = X509_get0_pubkey(cert)) == NULL)
                 goto err;
-        if (!ssl_sigalg_pkey_ok(ctx->ssl, sigalg, pkey))
+        if ((sigalg = ssl_sigalg_for_peer(ctx->ssl, pkey,
+            signature_scheme)) == NULL)
                 goto err;
         ctx->hs->peer_sigalg = sigalg;
 
diff --git a/src/lib/libssl/tls13_server.c b/src/lib/libssl/tls13_server.c
index c3d4ca9bd8..ff410fbb34 100644
--- a/src/lib/libssl/tls13_server.c
+++ b/src/lib/libssl/tls13_server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_server.c,v 1.82 2021/06/29 19:10:08 jsing Exp $ */
+/* $OpenBSD: tls13_server.c,v 1.83 2021/06/29 19:20:39 jsing Exp $ */
 /*
  * Copyright (c) 2019, 2020 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2020 Bob Beck <beck@openbsd.org>
@@ -970,10 +970,6 @@ tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs)
         if (!CBS_get_u16_length_prefixed(cbs, &signature))
                 goto err;
 
-        if ((sigalg = ssl_sigalg_from_value(ctx->hs->negotiated_tls_version,
-            signature_scheme)) == NULL)
-                goto err;
-
         if (!CBB_init(&cbb, 0))
                 goto err;
         if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad,
@@ -994,7 +990,8 @@ tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs)
                 goto err;
         if ((pkey = X509_get0_pubkey(cert)) == NULL)
                 goto err;
-        if (!ssl_sigalg_pkey_ok(ctx->ssl, sigalg, pkey))
+        if ((sigalg = ssl_sigalg_for_peer(ctx->ssl, pkey,
+            signature_scheme)) == NULL)
                 goto err;
         ctx->hs->peer_sigalg = sigalg;