[PATCH] x86/sgx: Use SHA-256 library API instead of crypto_shash API

[Eric Biggers]

From: Eric Biggers <ebigg...@google.com>

This user of SHA-256 does not support any other algorithm, so the
crypto_shash abstraction provides no value.  Just use the SHA-256
library API instead, which is much simpler and easier to use.

Signed-off-by: Eric Biggers <ebigg...@google.com>
---

This patch is targeting the x86 tree for 6.16.

 arch/x86/Kconfig                 |  3 +--
 arch/x86/kernel/cpu/sgx/driver.h |  1 -
 arch/x86/kernel/cpu/sgx/ioctl.c  | 30 ++----------------------------
 3 files changed, 3 insertions(+), 31 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index faafd99e52292..bf4874ba4fcfb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1880,12 +1880,11 @@ config X86_INTEL_TSX_MODE_AUTO
 endchoice
 
 config X86_SGX
        bool "Software Guard eXtensions (SGX)"
        depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
-       depends on CRYPTO=y
-       depends on CRYPTO_SHA256=y
+       select CRYPTO_LIB_SHA256
        select MMU_NOTIFIER
        select NUMA_KEEP_MEMINFO if NUMA
        select XARRAY_MULTI
        help
          Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
diff --git a/arch/x86/kernel/cpu/sgx/driver.h b/arch/x86/kernel/cpu/sgx/driver.h
index 4eddb4d571ef2..30f39f92c98fc 100644
--- a/arch/x86/kernel/cpu/sgx/driver.h
+++ b/arch/x86/kernel/cpu/sgx/driver.h
@@ -1,10 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __ARCH_SGX_DRIVER_H__
 #define __ARCH_SGX_DRIVER_H__
 
-#include <crypto/hash.h>
 #include <linux/kref.h>
 #include <linux/mmu_notifier.h>
 #include <linux/radix-tree.h>
 #include <linux/rwsem.h>
 #include <linux/sched.h>
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 776a20172867e..66f1efa16fbb7 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -1,10 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
 /*  Copyright(c) 2016-20 Intel Corporation. */
 
 #include <asm/mman.h>
 #include <asm/sgx.h>
+#include <crypto/sha2.h>
 #include <linux/mman.h>
 #include <linux/delay.h>
 #include <linux/file.h>
 #include <linux/hashtable.h>
 #include <linux/highmem.h>
@@ -461,35 +462,10 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl 
*encl, void __user *arg)
                return -EFAULT;
 
        return ret;
 }
 
-static int __sgx_get_key_hash(struct crypto_shash *tfm, const void *modulus,
-                             void *hash)
-{
-       SHASH_DESC_ON_STACK(shash, tfm);
-
-       shash->tfm = tfm;
-
-       return crypto_shash_digest(shash, modulus, SGX_MODULUS_SIZE, hash);
-}
-
-static int sgx_get_key_hash(const void *modulus, void *hash)
-{
-       struct crypto_shash *tfm;
-       int ret;
-
-       tfm = crypto_alloc_shash("sha256", 0, CRYPTO_ALG_ASYNC);
-       if (IS_ERR(tfm))
-               return PTR_ERR(tfm);
-
-       ret = __sgx_get_key_hash(tfm, modulus, hash);
-
-       crypto_free_shash(tfm);
-       return ret;
-}
-
 static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct 
*sigstruct,
                         void *token)
 {
        u64 mrsigner[4];
        int i, j;
@@ -521,13 +497,11 @@ static int sgx_encl_init(struct sgx_encl *encl, struct 
sgx_sigstruct *sigstruct,
 
        if (sigstruct->body.xfrm & sigstruct->body.xfrm_mask &
            sgx_xfrm_reserved_mask)
                return -EINVAL;
 
-       ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
-       if (ret)
-               return ret;
+       sha256(sigstruct->modulus, SGX_MODULUS_SIZE, (u8 *)mrsigner);
 
        mutex_lock(&encl->lock);
 
        /*
         * ENCLS[EINIT] is interruptible because it has such a high latency,

base-commit: 33035b665157558254b3c21c3f049fd728e72368
-- 
2.49.0