Reorder structure fields to maximize usage of immediate offset access

include/mbedtls/ssl.h

@@ -1108,6 +1108,17 @@ mbedtls_dtls_srtp_info;
  */
 struct mbedtls_ssl_session
 {
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    unsigned char MBEDTLS_PRIVATE(mfl_code);     /*!< MaxFragmentLength negotiated by peer */
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+    unsigned char MBEDTLS_PRIVATE(exported);
+
+    /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
+     * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
+     * to be studied whether one of them can be removed. */
+    unsigned char MBEDTLS_PRIVATE(minor_ver);    /*!< The TLS version used in the session. */
+
 #if defined(MBEDTLS_HAVE_TIME)
     mbedtls_time_t MBEDTLS_PRIVATE(start);       /*!< starting time      */
 #endif
@@ -1117,13 +1128,6 @@ struct mbedtls_ssl_session
     unsigned char MBEDTLS_PRIVATE(id)[32];       /*!< session identifier */
     unsigned char MBEDTLS_PRIVATE(master)[48];   /*!< the master secret  */
 
-    unsigned char MBEDTLS_PRIVATE(exported);
-
-    /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
-     * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
-     * to be studied whether one of them can be removed. */
-    unsigned char MBEDTLS_PRIVATE(minor_ver);    /*!< The TLS version used in the session. */
-
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
     mbedtls_x509_crt *MBEDTLS_PRIVATE(peer_cert);       /*!< peer X.509 cert chain */
@@ -1143,10 +1147,6 @@ struct mbedtls_ssl_session
     uint32_t MBEDTLS_PRIVATE(ticket_lifetime);   /*!< ticket lifetime hint    */
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
-#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    unsigned char MBEDTLS_PRIVATE(mfl_code);     /*!< MaxFragmentLength negotiated by peer */
-#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
-
 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
     int MBEDTLS_PRIVATE(encrypt_then_mac);       /*!< flag for EtM activation                */
 #endif
@@ -1210,7 +1210,62 @@ typedef void mbedtls_ssl_export_keys_t( void *p_expkey,
  */
 struct mbedtls_ssl_config
 {
-    /* Group items by size (largest first) to minimize padding overhead */
+    /* Group items mostly by size. This helps to reduce memory wasted to
+     * padding. It also helps to keep smaller fields early in the structure,
+     * so that elements tend to be in the 128-element direct access window
+     * on Arm Thumb, which reduces the code size. */
+
+    unsigned char MBEDTLS_PRIVATE(max_major_ver);    /*!< max. major version used            */
+    unsigned char MBEDTLS_PRIVATE(max_minor_ver);    /*!< max. minor version used            */
+    unsigned char MBEDTLS_PRIVATE(min_major_ver);    /*!< min. major version used            */
+    unsigned char MBEDTLS_PRIVATE(min_minor_ver);    /*!< min. minor version used            */
+
+    /*
+     * Flags (could be bit-fields to save RAM, but separate bytes make
+     * the code smaller on architectures with an instruction for direct
+     * byte access).
+     */
+
+    uint8_t MBEDTLS_PRIVATE(endpoint);      /*!< 0: client, 1: server               */
+    uint8_t MBEDTLS_PRIVATE(transport);     /*!< 0: stream (TLS), 1: datagram (DTLS)    */
+    uint8_t MBEDTLS_PRIVATE(authmode);      /*!< MBEDTLS_SSL_VERIFY_XXX             */
+    /* needed even with renego disabled for LEGACY_BREAK_HANDSHAKE          */
+    uint8_t MBEDTLS_PRIVATE(allow_legacy_renegotiation); /*!< MBEDTLS_LEGACY_XXX   */
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    uint8_t MBEDTLS_PRIVATE(mfl_code);      /*!< desired fragment length indicator
+                                                 (MBEDTLS_SSL_MAX_FRAG_LEN_XXX) */
+#endif
+#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+    uint8_t MBEDTLS_PRIVATE(encrypt_then_mac); /*!< negotiate encrypt-then-mac?    */
+#endif
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+    uint8_t MBEDTLS_PRIVATE(extended_ms);   /*!< negotiate extended master secret?  */
+#endif
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+    uint8_t MBEDTLS_PRIVATE(anti_replay);   /*!< detect and prevent replay?         */
+#endif
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+    uint8_t MBEDTLS_PRIVATE(disable_renegotiation); /*!< disable renegotiation?     */
+#endif
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+    uint8_t MBEDTLS_PRIVATE(session_tickets);   /*!< use session tickets?           */
+#endif
+#if defined(MBEDTLS_SSL_SRV_C)
+    uint8_t MBEDTLS_PRIVATE(cert_req_ca_list);  /*!< enable sending CA list in
+                                                     Certificate Request messages? */
+    uint8_t MBEDTLS_PRIVATE(respect_cli_pref);  /*!< pick the ciphersuite according to
+                                                     the client's preferences rather
+                                                     than ours? */
+#endif
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+    uint8_t MBEDTLS_PRIVATE(ignore_unexpected_cid); /*!< Should DTLS record with
+                                                     *   unexpected CID
+                                                     *   lead to failure? */
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+#if defined(MBEDTLS_SSL_DTLS_SRTP)
+    uint8_t MBEDTLS_PRIVATE(dtls_srtp_mki_support); /* support having mki_value
+                                                       in the use_srtp extension? */
+#endif
 
     /*
      * Pointers
@@ -1365,7 +1420,7 @@ struct mbedtls_ssl_config
 #endif /* MBEDTLS_SSL_DTLS_SRTP */
 
     /*
-     * Numerical settings (int then char)
+     * Numerical settings (int)
      */
 
     uint32_t MBEDTLS_PRIVATE(read_timeout);          /*!< timeout for mbedtls_ssl_read (ms)  */
@@ -1388,55 +1443,6 @@ struct mbedtls_ssl_config
 #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
     unsigned int MBEDTLS_PRIVATE(dhm_min_bitlen);    /*!< min. bit length of the DHM prime   */
 #endif
-
-    unsigned char MBEDTLS_PRIVATE(max_major_ver);    /*!< max. major version used            */
-    unsigned char MBEDTLS_PRIVATE(max_minor_ver);    /*!< max. minor version used            */
-    unsigned char MBEDTLS_PRIVATE(min_major_ver);    /*!< min. major version used            */
-    unsigned char MBEDTLS_PRIVATE(min_minor_ver);    /*!< min. minor version used            */
-
-    /*
-     * Flags (bitfields)
-     */
-
-    unsigned int MBEDTLS_PRIVATE(endpoint) : 1;      /*!< 0: client, 1: server               */
-    unsigned int MBEDTLS_PRIVATE(transport) : 1;     /*!< stream (TLS) or datagram (DTLS)    */
-    unsigned int MBEDTLS_PRIVATE(authmode) : 2;      /*!< MBEDTLS_SSL_VERIFY_XXX             */
-    /* needed even with renego disabled for LEGACY_BREAK_HANDSHAKE          */
-    unsigned int MBEDTLS_PRIVATE(allow_legacy_renegotiation) : 2 ; /*!< MBEDTLS_LEGACY_XXX   */
-#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
-    unsigned int MBEDTLS_PRIVATE(mfl_code) : 3;      /*!< desired fragment length            */
-#endif
-#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
-    unsigned int MBEDTLS_PRIVATE(encrypt_then_mac) : 1 ; /*!< negotiate encrypt-then-mac?    */
-#endif
-#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
-    unsigned int MBEDTLS_PRIVATE(extended_ms) : 1;   /*!< negotiate extended master secret?  */
-#endif
-#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
-    unsigned int MBEDTLS_PRIVATE(anti_replay) : 1;   /*!< detect and prevent replay?         */
-#endif
-#if defined(MBEDTLS_SSL_RENEGOTIATION)
-    unsigned int MBEDTLS_PRIVATE(disable_renegotiation) : 1; /*!< disable renegotiation?     */
-#endif
-#if defined(MBEDTLS_SSL_SESSION_TICKETS)
-    unsigned int MBEDTLS_PRIVATE(session_tickets) : 1;   /*!< use session tickets?           */
-#endif
-#if defined(MBEDTLS_SSL_SRV_C)
-    unsigned int MBEDTLS_PRIVATE(cert_req_ca_list) : 1;  /*!< enable sending CA list in
-                                          Certificate Request messages?     */
-    unsigned int MBEDTLS_PRIVATE(respect_cli_pref) : 1;  /*!< pick the ciphersuite according to
-                                          the client's preferences rather
-                                          than ours                         */
-#endif
-#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    unsigned int MBEDTLS_PRIVATE(ignore_unexpected_cid) : 1; /*!< Determines whether DTLS
-                                             *   record with unexpected CID
-                                             *   should lead to failure.    */
-#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
-#if defined(MBEDTLS_SSL_DTLS_SRTP)
-    unsigned int MBEDTLS_PRIVATE(dtls_srtp_mki_support) : 1; /* support having mki_value
-                                               in the use_srtp extension     */
-#endif
 };
 
 struct mbedtls_ssl_context

include/psa/crypto_driver_common.h

@@ -42,6 +42,9 @@
  * of these types. */
 #include "crypto_types.h"
 #include "crypto_values.h"
+/* Include size definitions which are used to size some arrays in operation
+ * structures. */
+#include <psa/crypto_sizes.h>
 
 /** For encrypt-decrypt functions, whether the operation is an encryption
  * or a decryption. */

include/psa/crypto_extra.h

@@ -31,6 +31,7 @@
 
 #include "mbedtls/platform_util.h"
 
+#include "crypto_types.h"
 #include "crypto_compat.h"
 
 #ifdef __cplusplus

include/psa/crypto_struct.h

@@ -186,16 +186,16 @@ typedef struct
 {
     uint8_t *MBEDTLS_PRIVATE(info);
     size_t MBEDTLS_PRIVATE(info_length);
-    psa_mac_operation_t MBEDTLS_PRIVATE(hmac);
-    uint8_t MBEDTLS_PRIVATE(prk)[PSA_HASH_MAX_SIZE];
-    uint8_t MBEDTLS_PRIVATE(output_block)[PSA_HASH_MAX_SIZE];
 #if PSA_HASH_MAX_SIZE > 0xff
 #error "PSA_HASH_MAX_SIZE does not fit in uint8_t"
 #endif
     uint8_t MBEDTLS_PRIVATE(offset_in_block);
     uint8_t MBEDTLS_PRIVATE(block_number);
     unsigned int MBEDTLS_PRIVATE(state) : 2;
     unsigned int MBEDTLS_PRIVATE(info_set) : 1;
+    uint8_t MBEDTLS_PRIVATE(output_block)[PSA_HASH_MAX_SIZE];
+    uint8_t MBEDTLS_PRIVATE(prk)[PSA_HASH_MAX_SIZE];
+    struct psa_mac_operation_s MBEDTLS_PRIVATE(hmac);
 } psa_hkdf_key_derivation_t;
 #endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF */
 

library/psa_crypto.c

@@ -103,9 +103,9 @@ static int key_type_is_raw_bytes( psa_key_type_t type )
 
 typedef struct
 {
-    mbedtls_psa_random_context_t rng;
     unsigned initialized : 1;
     unsigned rng_state : 2;
+    mbedtls_psa_random_context_t rng;
 } psa_global_data_t;
 
 static psa_global_data_t global_data;