[PATCH net-next] r8152: use SHA-256 library API instead of crypto_shash API

[PATCH net-next] r8152: use SHA-256 library API instead of crypto_shash API

[Eric Biggers]

From: Eric Biggers <ebiggers@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 <ebiggers@google.com>
---
 drivers/net/usb/Kconfig |  4 +---
 drivers/net/usb/r8152.c | 46 +++++++----------------------------------
 2 files changed, 8 insertions(+), 42 deletions(-)

diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index 3c360d4f06352..370b32fc25880 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -99,13 +99,11 @@ config USB_RTL8150
 config USB_RTL8152
 	tristate "Realtek RTL8152/RTL8153 Based USB Ethernet Adapters"
 	select MII
 	select PHYLIB
 	select CRC32
-	select CRYPTO
-	select CRYPTO_HASH
-	select CRYPTO_SHA256
+	select CRYPTO_LIB_SHA256
 	help
 	  This option adds support for Realtek RTL8152 based USB 2.0
 	  10/100 Ethernet adapters and RTL8153 based USB 3.0 10/100/1000
 	  Ethernet adapters.
 
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 2cab046749a92..67f5d30ffcbab 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -24,11 +24,11 @@
 #include <linux/usb/cdc.h>
 #include <linux/suspend.h>
 #include <linux/atomic.h>
 #include <linux/acpi.h>
 #include <linux/firmware.h>
-#include <crypto/hash.h>
+#include <crypto/sha2.h>
 #include <linux/usb/r8152.h>
 #include <net/gso.h>
 
 /* Information for net-next */
 #define NETNEXT_VERSION		"12"
@@ -4626,52 +4626,20 @@ static bool rtl8152_is_fw_mac_ok(struct r8152 *tp, struct fw_mac *mac)
  * make sure the file is correct.
  */
 static long rtl8152_fw_verify_checksum(struct r8152 *tp,
 				       struct fw_header *fw_hdr, size_t size)
 {
-	unsigned char checksum[sizeof(fw_hdr->checksum)];
-	struct crypto_shash *alg;
-	struct shash_desc *sdesc;
-	size_t len;
-	long rc;
-
-	alg = crypto_alloc_shash("sha256", 0, 0);
-	if (IS_ERR(alg)) {
-		rc = PTR_ERR(alg);
-		goto out;
-	}
-
-	if (crypto_shash_digestsize(alg) != sizeof(fw_hdr->checksum)) {
-		rc = -EFAULT;
-		dev_err(&tp->intf->dev, "digestsize incorrect (%u)\n",
-			crypto_shash_digestsize(alg));
-		goto free_shash;
-	}
+	u8 checksum[sizeof(fw_hdr->checksum)];
 
-	len = sizeof(*sdesc) + crypto_shash_descsize(alg);
-	sdesc = kmalloc(len, GFP_KERNEL);
-	if (!sdesc) {
-		rc = -ENOMEM;
-		goto free_shash;
-	}
-	sdesc->tfm = alg;
-
-	len = size - sizeof(fw_hdr->checksum);
-	rc = crypto_shash_digest(sdesc, fw_hdr->version, len, checksum);
-	kfree(sdesc);
-	if (rc)
-		goto free_shash;
+	BUILD_BUG_ON(sizeof(checksum) != SHA256_DIGEST_SIZE);
+	sha256(fw_hdr->version, size - sizeof(checksum), checksum);
 
-	if (memcmp(fw_hdr->checksum, checksum, sizeof(fw_hdr->checksum))) {
+	if (memcmp(fw_hdr->checksum, checksum, sizeof(checksum))) {
 		dev_err(&tp->intf->dev, "checksum fail\n");
-		rc = -EFAULT;
+		return -EFAULT;
 	}
-
-free_shash:
-	crypto_free_shash(alg);
-out:
-	return rc;
+	return 0;
 }
 
 static long rtl8152_check_firmware(struct r8152 *tp, struct rtl_fw *rtl_fw)
 {
 	const struct firmware *fw = rtl_fw->fw;

base-commit: 33035b665157558254b3c21c3f049fd728e72368
-- 
2.49.0

Re: [PATCH net-next] r8152: use SHA-256 library API instead of crypto_shash API

[Jakub Kicinski]

On Mon, 28 Apr 2025 12:16:06 -0700 Eric Biggers wrote:
> From: Eric Biggers <ebiggers@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 <ebiggers@google.com>

Applied, thanks!