From 0340085c67852c5a9b0aed8a03c1ccf2da82d5d7 Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Mon, 19 Feb 2018 20:28:37 -0800
Subject: [PATCH] smcComputeCmac implementation.

---
 exosphere/smc_api.c  |  4 ++++
 exosphere/smc_user.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/exosphere/smc_api.c b/exosphere/smc_api.c
index db5f804cf..eb95e41a6 100644
--- a/exosphere/smc_api.c
+++ b/exosphere/smc_api.c
@@ -277,6 +277,10 @@ uint32_t smc_crypt_aes(smc_args_t *args) {
     return smc_wrapper_async(args, user_crypt_aes, smc_crypt_aes_status_check);
 }
 
+uint32_t smc_compute_cmac(smc_args_t *args) {
+    return smc_wrapper_sync(args, user_compute_cmac);
+}
+
 
 
 uint32_t smc_cpu_on(smc_args_t *args) {
diff --git a/exosphere/smc_user.c b/exosphere/smc_user.c
index 64c8b11eb..1371baa1b 100644
--- a/exosphere/smc_user.c
+++ b/exosphere/smc_user.c
@@ -1,9 +1,11 @@
 #include <stdint.h>
 
 #include "utils.h"
+#include "cache.h"
 #include "smc_api.h"
 #include "smc_user.h"
 #include "se.h"
+#include "userpage.h"
 
 /* Globals. */
 int g_crypt_aes_done = 0;
@@ -87,4 +89,32 @@ uint32_t user_crypt_aes(smc_args_t *args) {
     }
     
     return result;
+}
+
+uint32_t user_compute_cmac(smc_args_t *args) {
+    uint32_t keyslot = (uint32_t)args->X[1];
+    void *user_address = (void *)args->X[2];
+    size_t size = (size_t)args->X[3];
+        
+    uint8_t user_data[0x400];
+    uint64_t result_cmac[2];
+    upage_ref_t page_ref;
+    
+    /* Validate keyslot and size. */
+    if (keyslot > 3 || args->X[3] > 0x400) {
+        return 2;
+    }
+    
+    if (upage_init(&page_ref, (void *)user_address) == 0 || user_copy_to_secure() == 0) {
+        return 2;
+    }
+    
+    flush_dcache_range(user_data, user_data + size);
+    se_compute_aes_128_cmac(keyslot, result_cmac, 0x10, user_data, size);
+    
+    /* Copy CMAC out. */
+    args->X[1] = result_cmac[0];
+    args->X[2] = result_cmac[1];
+    
+    return 0;
 }
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