commit d8ea37f1a3764727ea74ced95336368a9bce626c
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Thu Mar 09 10:46:22 2023 +0100
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Thu Mar 16 09:46:50 2023 +0100
tree 49ba3256909d161504ac894d8c11fdf2d93387d7
parent 12612e5ab45db3cd688a26ffaa3de56f252a74c9

Add engine field to context structure

For multi-part operations, we want to make the decision to use PSA or
not only once, during setup(), and remember it afterwards. This supports
the introduction, in the next few commits, of a dynamic component to
that decision: has the PSA driver sub-system been initialized yet?

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

library/md.c

diff --git a/library/md.c b/library/md.c
index 20bfd23..5b61b51 100644
--- a/library/md.c
+++ b/library/md.c
@@ -222,6 +222,7 @@
 
 void mbedtls_md_init(mbedtls_md_context_t *ctx)
 {
+    /* Note: this sets engine (if present) to MBEDTLS_MD_ENGINE_LEGACY */
     memset(ctx, 0, sizeof(mbedtls_md_context_t));
 }
 
@@ -233,7 +234,7 @@
 
     if (ctx->md_ctx != NULL) {
 #if defined(MBEDTLS_MD_SOME_PSA)
-        if (md_uses_psa(ctx->md_info) && ctx->md_ctx != NULL) {
+        if (ctx->engine == MBEDTLS_MD_ENGINE_PSA) {
             psa_hash_abort(ctx->md_ctx);
         } else
 #endif
@@ -299,7 +300,15 @@
     }
 
 #if defined(MBEDTLS_MD_SOME_PSA)
-    if (md_uses_psa(src->md_info)) {
+    if (src->engine != dst->engine) {
+        /* This can happen with src set to legacy because PSA wasn't ready
+         * yet, and dst to PSA because it became ready in the meantime.
+         * We currently don't support that case (we'd need to re-allocate
+         * md_ctx to the size of the appropriate MD context). */
+        return MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE;
+    }
+
+    if (src->engine == MBEDTLS_MD_ENGINE_PSA) {
         psa_status_t status = psa_hash_clone(src->md_ctx, dst->md_ctx);
         return mbedtls_md_error_from_psa(status);
     }
@@ -373,6 +382,7 @@
         if (ctx->md_ctx == NULL) {
             return MBEDTLS_ERR_MD_ALLOC_FAILED;
         }
+        ctx->engine = MBEDTLS_MD_ENGINE_PSA;
     } else
 #endif
     switch (md_info->type) {
@@ -434,8 +444,8 @@
     }
 
 #if defined(MBEDTLS_MD_SOME_PSA)
-    psa_algorithm_t alg = psa_alg_of_md(ctx->md_info);
-    if (alg != PSA_ALG_NONE) {
+    if (ctx->engine == MBEDTLS_MD_ENGINE_PSA) {
+        psa_algorithm_t alg = psa_alg_of_md(ctx->md_info);
         psa_hash_abort(ctx->md_ctx);
         psa_status_t status = psa_hash_setup(ctx->md_ctx, alg);
         return mbedtls_md_error_from_psa(status);
@@ -483,7 +493,7 @@
     }
 
 #if defined(MBEDTLS_MD_SOME_PSA)
-    if (md_uses_psa(ctx->md_info)) {
+    if (ctx->engine == MBEDTLS_MD_ENGINE_PSA) {
         psa_status_t status = psa_hash_update(ctx->md_ctx, input, ilen);
         return mbedtls_md_error_from_psa(status);
     }
@@ -530,7 +540,7 @@
     }
 
 #if defined(MBEDTLS_MD_SOME_PSA)
-    if (md_uses_psa(ctx->md_info)) {
+    if (ctx->engine == MBEDTLS_MD_ENGINE_PSA) {
         size_t size = ctx->md_info->size;
         psa_status_t status = psa_hash_finish(ctx->md_ctx,
                                               output, size, &size);
@@ -580,10 +590,9 @@
     }
 
 #if defined(MBEDTLS_MD_SOME_PSA)
-    psa_algorithm_t alg = psa_alg_of_md(md_info);
-    if (alg != PSA_ALG_NONE) {
+    if (md_uses_psa(md_info)) {
         size_t size = md_info->size;
-        psa_status_t status = psa_hash_compute(alg,
+        psa_status_t status = psa_hash_compute(psa_alg_of_md(md_info),
                                                input, ilen,
                                                output, size, &size);
         return mbedtls_md_error_from_psa(status);