linux-kernel - [PATCH v6 1/8] crypto: x86/glue_helper: Regularize function prototypes

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Message-Id: <20191122010334.12081-2-keescook@chromium.org>
Date:   Thu, 21 Nov 2019 17:03:27 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Kees Cook <keescook@...omium.org>,
        João Moreira <joao.moreira@...el.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Stephan Mueller <smueller@...onox.de>, x86@...nel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-hardening@...ts.openwall.com
Subject: [PATCH v6 1/8] crypto: x86/glue_helper: Regularize function prototypes

The crypto glue performed function prototype casting to make indirect
calls to assembly routines. Instead of performing casts at the call
sites (which trips Control Flow Integrity prototype checking), switch
each prototype to a common standard set of arguments which allows the
incremental removal of the existing macros. In order to keep pointer
math unchanged, internal casting between u128 pointers and u8 pointers
is added.

Co-developed-by: João Moreira <joao.moreira@...el.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 arch/x86/crypto/glue_helper.c             | 23 ++++++++++++++---------
 arch/x86/include/asm/crypto/glue_helper.h | 13 +++++++------
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/arch/x86/crypto/glue_helper.c b/arch/x86/crypto/glue_helper.c
index d15b99397480..d3d91a0abf88 100644
--- a/arch/x86/crypto/glue_helper.c
+++ b/arch/x86/crypto/glue_helper.c
@@ -134,7 +134,8 @@ int glue_cbc_decrypt_req_128bit(const struct common_glue_ctx *gctx,
 				src -= num_blocks - 1;
 				dst -= num_blocks - 1;
 
-				gctx->funcs[i].fn_u.cbc(ctx, dst, src);
+				gctx->funcs[i].fn_u.cbc(ctx, (u8 *)dst,
+							(const u8 *)src);
 
 				nbytes -= func_bytes;
 				if (nbytes < bsize)
@@ -188,7 +189,9 @@ int glue_ctr_req_128bit(const struct common_glue_ctx *gctx,
 
 			/* Process multi-block batch */
 			do {
-				gctx->funcs[i].fn_u.ctr(ctx, dst, src, &ctrblk);
+				gctx->funcs[i].fn_u.ctr(ctx, (u8 *)dst,
+							(const u8 *)src,
+							&ctrblk);
 				src += num_blocks;
 				dst += num_blocks;
 				nbytes -= func_bytes;
@@ -210,7 +213,8 @@ int glue_ctr_req_128bit(const struct common_glue_ctx *gctx,
 
 		be128_to_le128(&ctrblk, (be128 *)walk.iv);
 		memcpy(&tmp, walk.src.virt.addr, nbytes);
-		gctx->funcs[gctx->num_funcs - 1].fn_u.ctr(ctx, &tmp, &tmp,
+		gctx->funcs[gctx->num_funcs - 1].fn_u.ctr(ctx, (u8 *)&tmp,
+							  (const u8 *)&tmp,
 							  &ctrblk);
 		memcpy(walk.dst.virt.addr, &tmp, nbytes);
 		le128_to_be128((be128 *)walk.iv, &ctrblk);
@@ -240,7 +244,8 @@ static unsigned int __glue_xts_req_128bit(const struct common_glue_ctx *gctx,
 
 		if (nbytes >= func_bytes) {
 			do {
-				gctx->funcs[i].fn_u.xts(ctx, dst, src,
+				gctx->funcs[i].fn_u.xts(ctx, (u8 *)dst,
+							(const u8 *)src,
 							walk->iv);
 
 				src += num_blocks;
@@ -354,8 +359,8 @@ int glue_xts_req_128bit(const struct common_glue_ctx *gctx,
 }
 EXPORT_SYMBOL_GPL(glue_xts_req_128bit);
 
-void glue_xts_crypt_128bit_one(void *ctx, u128 *dst, const u128 *src, le128 *iv,
-			       common_glue_func_t fn)
+void glue_xts_crypt_128bit_one(const void *ctx, u8 *dst, const u8 *src,
+			       le128 *iv, common_glue_func_t fn)
 {
 	le128 ivblk = *iv;
 
@@ -363,13 +368,13 @@ void glue_xts_crypt_128bit_one(void *ctx, u128 *dst, const u128 *src, le128 *iv,
 	gf128mul_x_ble(iv, &ivblk);
 
 	/* CC <- T xor C */
-	u128_xor(dst, src, (u128 *)&ivblk);
+	u128_xor((u128 *)dst, (const u128 *)src, (u128 *)&ivblk);
 
 	/* PP <- D(Key2,CC) */
-	fn(ctx, (u8 *)dst, (u8 *)dst);
+	fn(ctx, dst, dst);
 
 	/* P <- T xor PP */
-	u128_xor(dst, dst, (u128 *)&ivblk);
+	u128_xor((u128 *)dst, (u128 *)dst, (u128 *)&ivblk);
 }
 EXPORT_SYMBOL_GPL(glue_xts_crypt_128bit_one);
 
diff --git a/arch/x86/include/asm/crypto/glue_helper.h b/arch/x86/include/asm/crypto/glue_helper.h
index 8d4a8e1226ee..ba48d5af4f16 100644
--- a/arch/x86/include/asm/crypto/glue_helper.h
+++ b/arch/x86/include/asm/crypto/glue_helper.h
@@ -11,11 +11,11 @@
 #include <asm/fpu/api.h>
 #include <crypto/b128ops.h>
 
-typedef void (*common_glue_func_t)(void *ctx, u8 *dst, const u8 *src);
-typedef void (*common_glue_cbc_func_t)(void *ctx, u128 *dst, const u128 *src);
-typedef void (*common_glue_ctr_func_t)(void *ctx, u128 *dst, const u128 *src,
+typedef void (*common_glue_func_t)(const void *ctx, u8 *dst, const u8 *src);
+typedef void (*common_glue_cbc_func_t)(const void *ctx, u8 *dst, const u8 *src);
+typedef void (*common_glue_ctr_func_t)(const void *ctx, u8 *dst, const u8 *src,
 				       le128 *iv);
-typedef void (*common_glue_xts_func_t)(void *ctx, u128 *dst, const u128 *src,
+typedef void (*common_glue_xts_func_t)(const void *ctx, u8 *dst, const u8 *src,
 				       le128 *iv);
 
 #define GLUE_FUNC_CAST(fn) ((common_glue_func_t)(fn))
@@ -116,7 +116,8 @@ extern int glue_xts_req_128bit(const struct common_glue_ctx *gctx,
 			       common_glue_func_t tweak_fn, void *tweak_ctx,
 			       void *crypt_ctx, bool decrypt);
 
-extern void glue_xts_crypt_128bit_one(void *ctx, u128 *dst, const u128 *src,
-				      le128 *iv, common_glue_func_t fn);
+extern void glue_xts_crypt_128bit_one(const void *ctx, u8 *dst,
+				      const u8 *src, le128 *iv,
+				      common_glue_func_t fn);
 
 #endif /* _CRYPTO_GLUE_HELPER_H */
-- 
2.17.1