From 558d96240bea7d910144fa2cad1fe2f8061ffa74 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 17 Aug 2022 11:32:38 +0200
Subject: [PATCH] sha256: add sha256_direct()/SHA256_DIRECT() helpers

---
 src/basic/hmac.c           |  4 +---
 src/boot/efi/random-seed.c | 13 ++-----------
 src/fundamental/sha256.c   |  7 +++++++
 src/fundamental/sha256.h   |  4 ++++
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/basic/hmac.c b/src/basic/hmac.c
index 1e4e380aaa9..a5f66d56056 100644
--- a/src/basic/hmac.c
+++ b/src/basic/hmac.c
@@ -29,9 +29,7 @@ void hmac_sha256(const void *key,
 
         /* The key needs to be block size length or less, hash it if it's longer. */
         if (key_size > HMAC_BLOCK_SIZE) {
-                sha256_init_ctx(&hash);
-                sha256_process_bytes(key, key_size, &hash);
-                sha256_finish_ctx(&hash, replacement_key);
+                sha256_direct(key, key_size, replacement_key);
                 key = replacement_key;
                 key_size = SHA256_DIGEST_SIZE;
         }
diff --git a/src/boot/efi/random-seed.c b/src/boot/efi/random-seed.c
index 652634bdc9b..aea4f7e5326 100644
--- a/src/boot/efi/random-seed.c
+++ b/src/boot/efi/random-seed.c
@@ -215,17 +215,8 @@ static void validate_sha256(void) {
                     0xaf, 0xac, 0x45, 0x03, 0x7a, 0xfe, 0xe9, 0xd1 }},
         };
 
-        for (UINTN i = 0; i < ELEMENTSOF(array); i++) {
-                struct sha256_ctx hash;
-                uint8_t result[HASH_VALUE_SIZE];
-
-                sha256_init_ctx(&hash);
-                sha256_process_bytes(array[i].string, strlen8(array[i].string), &hash);
-                sha256_finish_ctx(&hash, result);
-
-                assert(memcmp(result, array[i].hash, HASH_VALUE_SIZE) == 0);
-        }
-
+        for (UINTN i = 0; i < ELEMENTSOF(array); i++)
+                assert(memcmp(SHA256_DIRECT(array[i].string, strlen8(array[i].string)), array[i].hash, HASH_VALUE_SIZE) == 0);
 #endif
 }
 
diff --git a/src/fundamental/sha256.c b/src/fundamental/sha256.c
index 7ead5f169c5..43ee996b6f7 100644
--- a/src/fundamental/sha256.c
+++ b/src/fundamental/sha256.c
@@ -289,3 +289,10 @@ static void sha256_process_block(const void *buffer, size_t len, struct sha256_c
         ctx->H[6] = g;
         ctx->H[7] = h;
 }
+
+uint8_t* sha256_direct(const void *buffer, size_t sz, uint8_t result[static SHA256_DIGEST_SIZE]) {
+        struct sha256_ctx ctx;
+        sha256_init_ctx(&ctx);
+        sha256_process_bytes(buffer, sz, &ctx);
+        return sha256_finish_ctx(&ctx, result);
+}
diff --git a/src/fundamental/sha256.h b/src/fundamental/sha256.h
index 337e746c498..31790c2ebd1 100644
--- a/src/fundamental/sha256.h
+++ b/src/fundamental/sha256.h
@@ -27,3 +27,7 @@ struct sha256_ctx {
 void sha256_init_ctx(struct sha256_ctx *ctx);
 uint8_t *sha256_finish_ctx(struct sha256_ctx *ctx, uint8_t resbuf[static SHA256_DIGEST_SIZE]);
 void sha256_process_bytes(const void *buffer, size_t len, struct sha256_ctx *ctx);
+
+uint8_t* sha256_direct(const void *buffer, size_t sz, uint8_t result[static SHA256_DIGEST_SIZE]);
+
+#define SHA256_DIRECT(buffer, sz) sha256_direct(buffer, sz, (uint8_t[SHA256_DIGEST_SIZE]) {})