Squashed commit upgrading to mbedtls-2.22.0

Squash merging branch import/mbedtls-2.22.0

5cab03377186 ("mk/clang.mk: define libgcc$(sm)")
3607a5386a72 ("core: mbedtls: enable MBEDTLS_ECDH_LEGACY_CONTEXT")
896c8845bbda ("mbedtls: remove file md_wrap.c from build")
400b2af54fa0 ("libmbedtls: mbedtls_mpi_exp_mod(): optimize mempool usage")
777827c7af3d ("libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage")
549e4600678e ("libmbedtls: preserve mempool usage on reinit")
02d636083fe2 ("libmbedtls: mbedtls_mpi_exp_mod() initialize W")
d2ac2b3c92bf ("libmbedtls: fix no CRT issue")
f550879d5be2 ("libmbedtls: add interfaces in mbedtls for context memory operation")
219173d807ce ("libmedtls: mpi_miller_rabin: increase count limit")
7930b0b6b5e4 ("libmbedtls: add mbedtls_mpi_init_mempool()")
78af9fdc120f ("libmbedtls: make mbedtls_mpi_mont*() available")
8f7357271cc2 ("libmbedtls: refine mbedtls license header")
c5993878881f ("mbedtls: configure mbedtls to reach for config")
6f9c587783af ("mbedtls: remove default include/mbedtls/config.h")
3d3bd3b12752 ("Import mbedtls-2.22.0")

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/ssl_cache.c b/lib/libmbedtls/mbedtls/library/ssl_cache.c
index 4d8c866..07dcc88 100644
--- a/lib/libmbedtls/mbedtls/library/ssl_cache.c
+++ b/lib/libmbedtls/mbedtls/library/ssl_cache.c
@@ -40,6 +40,7 @@
 #endif
 
 #include "mbedtls/ssl_cache.h"
+#include "mbedtls/ssl_internal.h"
 
 #include <string.h>
 
@@ -92,16 +93,24 @@
                     entry->session.id_len ) != 0 )
             continue;
 
-        memcpy( session->master, entry->session.master, 48 );
+        ret = mbedtls_ssl_session_copy( session, &entry->session );
+        if( ret != 0 )
+        {
+            ret = 1;
+            goto exit;
+        }
 
-        session->verify_result = entry->session.verify_result;
-
-#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
         /*
          * Restore peer certificate (without rest of the original chain)
          */
         if( entry->peer_cert.p != NULL )
         {
+            /* `session->peer_cert` is NULL after the call to
+             * mbedtls_ssl_session_copy(), because cache entries
+             * have the `peer_cert` field set to NULL. */
+
             if( ( session->peer_cert = mbedtls_calloc( 1,
                                  sizeof(mbedtls_x509_crt) ) ) == NULL )
             {
@@ -119,7 +128,7 @@
                 goto exit;
             }
         }
-#endif /* MBEDTLS_X509_CRT_PARSE_C */
+#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 
         ret = 0;
         goto exit;
@@ -239,9 +248,8 @@
 #endif
     }
 
-    memcpy( &cur->session, session, sizeof( mbedtls_ssl_session ) );
-
-#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
     /*
      * If we're reusing an entry, free its certificate first
      */
@@ -250,26 +258,43 @@
         mbedtls_free( cur->peer_cert.p );
         memset( &cur->peer_cert, 0, sizeof(mbedtls_x509_buf) );
     }
+#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 
-    /*
-     * Store peer certificate
-     */
-    if( session->peer_cert != NULL )
+    /* Copy the entire session; this temporarily makes a copy of the
+     * X.509 CRT structure even though we only want to store the raw CRT.
+     * This inefficiency will go away as soon as we implement on-demand
+     * parsing of CRTs, in which case there's no need for the `peer_cert`
+     * field anymore in the first place, and we're done after this call. */
+    ret = mbedtls_ssl_session_copy( &cur->session, session );
+    if( ret != 0 )
     {
-        cur->peer_cert.p = mbedtls_calloc( 1, session->peer_cert->raw.len );
+        ret = 1;
+        goto exit;
+    }
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+    /* If present, free the X.509 structure and only store the raw CRT data. */
+    if( cur->session.peer_cert != NULL )
+    {
+        cur->peer_cert.p =
+            mbedtls_calloc( 1, cur->session.peer_cert->raw.len );
         if( cur->peer_cert.p == NULL )
         {
             ret = 1;
             goto exit;
         }
 
-        memcpy( cur->peer_cert.p, session->peer_cert->raw.p,
-                session->peer_cert->raw.len );
+        memcpy( cur->peer_cert.p,
+                cur->session.peer_cert->raw.p,
+                cur->session.peer_cert->raw.len );
         cur->peer_cert.len = session->peer_cert->raw.len;
 
+        mbedtls_x509_crt_free( cur->session.peer_cert );
+        mbedtls_free( cur->session.peer_cert );
         cur->session.peer_cert = NULL;
     }
-#endif /* MBEDTLS_X509_CRT_PARSE_C */
+#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 
     ret = 0;
 
@@ -311,9 +336,10 @@
 
         mbedtls_ssl_session_free( &prv->session );
 
-#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
+    defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
         mbedtls_free( prv->peer_cert.p );
-#endif /* MBEDTLS_X509_CRT_PARSE_C */
+#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 
         mbedtls_free( prv );
     }