From 733ab0781327c061f0bbf22162a158784abf3334 Mon Sep 17 00:00:00 2001
From: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Date: Thu, 10 Nov 2022 14:23:38 +0100
Subject: [PATCH] Support big-endian platforms

---
 crypto/fipsmodule/aes/aes_nohw.c | 12 +++++++++
 crypto/internal.h                | 42 ++++++++++++++++++++++++--------
 src/lib.rs                       |  8 ++++--
 3 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/crypto/fipsmodule/aes/aes_nohw.c b/crypto/fipsmodule/aes/aes_nohw.c
index 1b35f635a6..731178516d 100644
--- a/crypto/fipsmodule/aes/aes_nohw.c
+++ b/crypto/fipsmodule/aes/aes_nohw.c
@@ -273,6 +273,9 @@ static inline aes_word_t aes_nohw_delta_swap(aes_word_t a, aes_word_t mask,
 // http://programming.sirrida.de/calcperm.php on smaller inputs.
 #if defined(OPENSSL_64_BIT)
 static inline uint64_t aes_nohw_compact_word(uint64_t a) {
+#if defined(RING_BIG_ENDIAN)
+  a = CRYPTO_bswap8(a);
+#endif
   // Numbering the 64/2 = 16 4-bit chunks, least to most significant, we swap
   // quartets of those chunks:
   //   0 1 2 3 | 4 5 6 7 | 8  9 10 11 | 12 13 14 15 =>
@@ -294,10 +297,16 @@ static inline uint64_t aes_nohw_uncompact_word(uint64_t a) {
   a = aes_nohw_delta_swap(a, UINT64_C(0x00000000ffff0000), 16);
   a = aes_nohw_delta_swap(a, UINT64_C(0x0000ff000000ff00), 8);
   a = aes_nohw_delta_swap(a, UINT64_C(0x00f000f000f000f0), 4);
+#if defined(RING_BIG_ENDIAN)
+  a = CRYPTO_bswap8(a);
+#endif
   return a;
 }
 #else   // !OPENSSL_64_BIT
 static inline uint32_t aes_nohw_compact_word(uint32_t a) {
+#if defined(RING_BIG_ENDIAN)
+  a = CRYPTO_bswap4(a);
+#endif
   // Numbering the 32/2 = 16 pairs of bits, least to most significant, we swap:
   //   0 1 2 3 | 4 5 6 7 | 8  9 10 11 | 12 13 14 15 =>
   //   0 4 2 6 | 1 5 3 7 | 8 12 10 14 |  9 13 11 15
@@ -316,6 +325,9 @@ static inline uint32_t aes_nohw_uncompact_word(uint32_t a) {
   // Reverse the steps of |aes_nohw_uncompact_word|.
   a = aes_nohw_delta_swap(a, 0x0000f0f0, 12);
   a = aes_nohw_delta_swap(a, 0x00cc00cc, 6);
+#if defined(RING_BIG_ENDIAN)
+  a = CRYPTO_bswap4(a);
+#endif
   return a;
 }
 
diff --git a/crypto/internal.h b/crypto/internal.h
index 0de2a3e86b..5f92e34e3f 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -401,55 +401,77 @@ static inline void *OPENSSL_memset(void *dst, int c, size_t n) {
 // endianness. They use |memcpy|, and so avoid alignment or strict aliasing
 // requirements on the input and output pointers.
 
+#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__)
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define RING_BIG_ENDIAN
+#endif
+#endif
+
 static inline uint32_t CRYPTO_load_u32_le(const void *in) {
   uint32_t v;
   OPENSSL_memcpy(&v, in, sizeof(v));
+#if defined(RING_BIG_ENDIAN)
+  return CRYPTO_bswap4(v);
+#else
   return v;
+#endif
 }
 
 static inline void CRYPTO_store_u32_le(void *out, uint32_t v) {
+#if defined(RING_BIG_ENDIAN)
+  v = CRYPTO_bswap4(v);
+#endif
   OPENSSL_memcpy(out, &v, sizeof(v));
 }
 
 static inline uint32_t CRYPTO_load_u32_be(const void *in) {
   uint32_t v;
   OPENSSL_memcpy(&v, in, sizeof(v));
+#if !defined(RING_BIG_ENDIAN)
   return CRYPTO_bswap4(v);
+#else
+  return v;
+#endif
 }
 
 static inline void CRYPTO_store_u32_be(void *out, uint32_t v) {
+#if !defined(RING_BIG_ENDIAN)
   v = CRYPTO_bswap4(v);
+#endif
   OPENSSL_memcpy(out, &v, sizeof(v));
 }
 
 static inline uint64_t CRYPTO_load_u64_le(const void *in) {
   uint64_t v;
   OPENSSL_memcpy(&v, in, sizeof(v));
+#if defined(RING_BIG_ENDIAN)
+  return CRYPTO_bswap8(v);
+#else
   return v;
+#endif
 }
 
 static inline void CRYPTO_store_u64_le(void *out, uint64_t v) {
+#if defined(RING_BIG_ENDIAN)
+  v = CRYPTO_bswap8(v);
+#endif
   OPENSSL_memcpy(out, &v, sizeof(v));
 }
 
 static inline uint64_t CRYPTO_load_u64_be(const void *ptr) {
   uint64_t ret;
   OPENSSL_memcpy(&ret, ptr, sizeof(ret));
+#if !defined(RING_BIG_ENDIAN)
   return CRYPTO_bswap8(ret);
+#else
+  return ret;
+#endif
 }
 
 static inline void CRYPTO_store_u64_be(void *out, uint64_t v) {
+#if !defined(RING_BIG_ENDIAN)
   v = CRYPTO_bswap8(v);
-  OPENSSL_memcpy(out, &v, sizeof(v));
-}
-
-static inline crypto_word_t CRYPTO_load_word_le(const void *in) {
-  crypto_word_t v;
-  OPENSSL_memcpy(&v, in, sizeof(v));
-  return v;
-}
-
-static inline void CRYPTO_store_word_le(void *out, crypto_word_t v) {
+#endif
   OPENSSL_memcpy(out, &v, sizeof(v));
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index 644708c828..99e1ff3ee6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -115,5 +115,9 @@ mod sealed {
     pub trait Sealed {}
 }
 
-// TODO: https://github.com/briansmith/ring/issues/1555.
-const _LITTLE_ENDIAN_ONLY: () = assert!(cfg!(target_endian = "little"));
+// XXX: 64-bit big endian is tested; 32-bit is not.
+// TODO: Add 32-bit big endian test coverage to CI.
+const _ENDIAN_TESTING: () = assert!(cfg!(any(
+    target_endian = "little",
+    target_pointer_width = "64"
+)));