Convert Sigalgs processing to use ints

In TLSv1.2 an individual sig alg is represented by 1 byte for the hash
and 1 byte for the signature. In TLSv1.3 each sig alg is represented by
two bytes, where the two bytes together represent a single hash and
signature combination. This converts the internal representation of sigalgs
to use a single int for the pair, rather than a pair of bytes.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2157)

5 files changed, 17 insertions, 15 deletions

diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index be0c979eb9..18f5ca3d1b 100644
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -226,7 +226,7 @@ int tls_construct_ctos_sig_algs(SSL *s, WPACKET *pkt, X509 *x, size_t chainidx,
                                 int *al)
 {
     size_t salglen;
-    const unsigned char *salg;
+    const unsigned int *salg;
 
     if (!SSL_CLIENT_USE_SIGALGS(s))
         return 1;
diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
index c868bb9e2c..d58eedda3a 100644
--- a/ssl/statem/extensions_srvr.c
+++ b/ssl/statem/extensions_srvr.c
@@ -204,15 +204,13 @@ int tls_parse_ctos_sig_algs(SSL *s, PACKET *pkt, X509 *x, size_t chainidx,
     PACKET supported_sig_algs;
 
     if (!PACKET_as_length_prefixed_2(pkt, &supported_sig_algs)
-            || (PACKET_remaining(&supported_sig_algs) % 2) != 0
             || PACKET_remaining(&supported_sig_algs) == 0) {
         *al = SSL_AD_DECODE_ERROR;
         return 0;
     }
 
-    if (!s->hit && !tls1_save_sigalgs(s, PACKET_data(&supported_sig_algs),
-                                      PACKET_remaining(&supported_sig_algs))) {
-        *al = TLS1_AD_INTERNAL_ERROR;
+    if (!s->hit && !tls1_save_sigalgs(s, &supported_sig_algs)) {
+        *al = TLS1_AD_DECODE_ERROR;
         return 0;
     }
 
diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index ff57e9217a..432dc915b7 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -1880,14 +1880,15 @@ MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt)
         }
 
         if (SSL_USE_SIGALGS(s)) {
-            const unsigned char *sigalgs;
+            unsigned int sigalg;
             int rv;
-            if (!PACKET_get_bytes(pkt, &sigalgs, 2)) {
+
+            if (!PACKET_get_net_2(pkt, &sigalg)) {
                 al = SSL_AD_DECODE_ERROR;
                 SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, SSL_R_LENGTH_TOO_SHORT);
                 goto err;
             }
-            rv = tls12_check_peer_sigalg(&md, s, sigalgs, pkey);
+            rv = tls12_check_peer_sigalg(&md, s, sigalg, pkey);
             if (rv == -1) {
                 al = SSL_AD_INTERNAL_ERROR;
                 goto err;
@@ -2026,8 +2027,9 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL *s, PACKET *pkt)
         s->s3->tmp.ctype[i] = data[i];
 
     if (SSL_USE_SIGALGS(s)) {
-        if (!PACKET_get_net_2(pkt, &list_len)
-            || !PACKET_get_bytes(pkt, &data, list_len)) {
+        PACKET sigalgs;
+
+        if (!PACKET_get_length_prefixed_2(pkt, &sigalgs)) {
             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
             SSLerr(SSL_F_TLS_PROCESS_CERTIFICATE_REQUEST,
                    SSL_R_LENGTH_MISMATCH);
@@ -2039,7 +2041,7 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL *s, PACKET *pkt)
             s->s3->tmp.md[i] = NULL;
             s->s3->tmp.valid_flags[i] = 0;
         }
-        if ((list_len & 1) || !tls1_save_sigalgs(s, data, list_len)) {
+        if (!tls1_save_sigalgs(s, &sigalgs)) {
             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
             SSLerr(SSL_F_TLS_PROCESS_CERTIFICATE_REQUEST,
                    SSL_R_SIGNATURE_ALGORITHMS_ERROR);
diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index 827de4be34..4353202e39 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -238,7 +238,7 @@ int tls_construct_cert_verify(SSL *s, WPACKET *pkt)
 MSG_PROCESS_RETURN tls_process_cert_verify(SSL *s, PACKET *pkt)
 {
     EVP_PKEY *pkey = NULL;
-    const unsigned char *sig, *data;
+    const unsigned char *data;
 #ifndef OPENSSL_NO_GOST
     unsigned char *gost_data = NULL;
 #endif
@@ -284,12 +284,13 @@ MSG_PROCESS_RETURN tls_process_cert_verify(SSL *s, PACKET *pkt)
     {
         if (SSL_USE_SIGALGS(s)) {
             int rv;
+            unsigned int sigalg;
 
-            if (!PACKET_get_bytes(pkt, &sig, 2)) {
+            if (!PACKET_get_net_2(pkt, &sigalg)) {
                 al = SSL_AD_DECODE_ERROR;
                 goto f_err;
             }
-            rv = tls12_check_peer_sigalg(&md, s, sig, pkey);
+            rv = tls12_check_peer_sigalg(&md, s, sigalg, pkey);
             if (rv == -1) {
                 goto f_err;
             } else if (rv == 0) {
diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c
index d08ed6f77b..12eb6aeb42 100644
--- a/ssl/statem/statem_srvr.c
+++ b/ssl/statem/statem_srvr.c
@@ -2292,8 +2292,9 @@ int tls_construct_certificate_request(SSL *s, WPACKET *pkt)
     }
 
     if (SSL_USE_SIGALGS(s)) {
-        const unsigned char *psigs;
+        const unsigned int *psigs;
         size_t nl = tls12_get_psigalgs(s, &psigs);
+
         if (!WPACKET_start_sub_packet_u16(pkt)
                 || !tls12_copy_sigalgs(s, pkt, psigs, nl)
                 || !WPACKET_close(pkt)) {