1 files changed, 43 insertions, 25 deletions

diff --git a/src/lib/libssl/d1_pkt.c b/src/lib/libssl/d1_pkt.c
index 5bbdf5f738..dd7d9aa76c 100644
--- a/src/lib/libssl/d1_pkt.c
+++ b/src/lib/libssl/d1_pkt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: d1_pkt.c,v 1.77 2020/08/09 15:46:28 jsing Exp $ */
+/* $OpenBSD: d1_pkt.c,v 1.78 2020/08/09 16:02:58 jsing Exp $ */
 /*
  * DTLS implementation written by Nagendra Modadugu
  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
@@ -1177,10 +1177,12 @@ do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
         SSL3_RECORD_INTERNAL *wr = &(S3I(s)->wrec);
         SSL3_BUFFER_INTERNAL *wb = &(S3I(s)->wbuf);
         SSL_SESSION *sess = s->session;
-        int eivlen = 0, mac_size = 0;
-        unsigned char *p;
+        int block_size = 0, eivlen = 0, mac_size = 0;
+        size_t pad_len, record_len;
+        CBB cbb, fragment;
+        size_t out_len;
+        uint8_t *p;
         int ret;
-        CBB cbb;
 
         memset(&cbb, 0, sizeof(cbb));
 
@@ -1209,12 +1211,38 @@ do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
                         goto err;
         }
 
+        /* Explicit IV length. */
+        if (s->internal->enc_write_ctx && SSL_USE_EXPLICIT_IV(s)) {
+                int mode = EVP_CIPHER_CTX_mode(s->internal->enc_write_ctx);
+                if (mode == EVP_CIPH_CBC_MODE) {
+                        eivlen = EVP_CIPHER_CTX_iv_length(s->internal->enc_write_ctx);
+                        if (eivlen <= 1)
+                                eivlen = 0;
+                }
+        } else if (s->internal->aead_write_ctx != NULL &&
+            s->internal->aead_write_ctx->variable_nonce_in_record) {
+                eivlen = s->internal->aead_write_ctx->variable_nonce_len;
+        }
+
+        /* Determine length of record fragment. */
+        record_len = eivlen + len + mac_size;
+        if (s->internal->enc_write_ctx != NULL) {
+                block_size = EVP_CIPHER_CTX_block_size(s->internal->enc_write_ctx);
+                if (block_size <= 0 || block_size > EVP_MAX_BLOCK_LENGTH)
+                        goto err;
+                if (block_size > 1) {
+                        pad_len = block_size - (record_len % block_size);
+                        record_len += pad_len;
+                }
+        } else if (s->internal->aead_write_ctx != NULL) {
+                record_len += s->internal->aead_write_ctx->tag_len;
+        }
+
         /* DTLS implements explicit IV, so no need for empty fragments. */
 
-        p = wb->buf;
         wb->offset = 0;
 
-        if (!CBB_init_fixed(&cbb, p, DTLS1_RT_HEADER_LENGTH))
+        if (!CBB_init_fixed(&cbb, wb->buf, wb->len))
                 goto err;
 
         /* Write the header. */
@@ -1226,21 +1254,10 @@ do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
                 goto err;
         if (!CBB_add_bytes(&cbb, &(S3I(s)->write_sequence[2]), 6))
                 goto err;
-
-        p += DTLS1_RT_HEADER_LENGTH;
-
-        /* Explicit IV length. */
-        if (s->internal->enc_write_ctx && SSL_USE_EXPLICIT_IV(s)) {
-                int mode = EVP_CIPHER_CTX_mode(s->internal->enc_write_ctx);
-                if (mode == EVP_CIPH_CBC_MODE) {
-                        eivlen = EVP_CIPHER_CTX_iv_length(s->internal->enc_write_ctx);
-                        if (eivlen <= 1)
-                                eivlen = 0;
-                }
-        } else if (s->internal->aead_write_ctx != NULL &&
-            s->internal->aead_write_ctx->variable_nonce_in_record) {
-                eivlen = s->internal->aead_write_ctx->variable_nonce_len;
-        }
+        if (!CBB_add_u16_length_prefixed(&cbb, &fragment))
+                goto err;
+        if (!CBB_add_space(&fragment, &p, record_len))
+                goto err;
 
         wr->type = type;
         wr->data = p + eivlen;
@@ -1262,11 +1279,14 @@ do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
         if (tls1_enc(s, 1) != 1)
                 goto err;
 
-        if (!CBB_add_u16(&cbb, wr->length))
+        if (wr->length != record_len)
                 goto err;
-        if (!CBB_finish(&cbb, NULL, NULL))
+
+        if (!CBB_finish(&cbb, NULL, &out_len))
                 goto err;
 
+        wb->left = out_len;
+
         /*
          * We should now have wr->data pointing to the encrypted data,
          * which is wr->length long.
@@ -1276,8 +1296,6 @@ do_dtls1_write(SSL *s, int type, const unsigned char *buf, unsigned int len)
 
         tls1_record_sequence_increment(S3I(s)->write_sequence);
 
-        wb->left = wr->length;
-
         /*
          * Memorize arguments so that ssl3_write_pending can detect
          * bad write retries later.