[PATCH] firmware_loader: use SHA-256 library API instead of crypto_shash API

Eric Biggers
2025-04-28T19:11:04Z

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.

Also take advantage of printk's built-in hex conversion using %*phN.

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

This patch is targeting the firmware_loader tree for 6.16.

drivers/base/firmware_loader/Kconfig | 4 +---
drivers/base/firmware_loader/main.c | 34 ++++------------------------
2 files changed, 5 insertions(+), 33 deletions(-)

diff --git a/drivers/base/firmware_loader/Kconfig b/drivers/base/firmware_loader/Kconfig
index a037016742651..752b9a9bea038 100644
--- a/drivers/base/firmware_loader/Kconfig
+++ b/drivers/base/firmware_loader/Kconfig
@@ -1,12 +1,11 @@
# SPDX-License-Identifier: GPL-2.0
menu "Firmware loader"

config FW_LOADER
tristate "Firmware loading facility" if EXPERT
- select CRYPTO_HASH if FW_LOADER_DEBUG
- select CRYPTO_SHA256 if FW_LOADER_DEBUG
+ select CRYPTO_LIB_SHA256 if FW_LOADER_DEBUG
default y
help
This enables the firmware loading facility in the kernel. The kernel
will first look for built-in firmware, if it has any. Next, it will
look for the requested firmware in a series of filesystem paths:
@@ -26,11 +25,10 @@ config FW_LOADER
You also want to be sure to enable this built-in if you are going to
enable built-in firmware (CONFIG_EXTRA_FIRMWARE).

config FW_LOADER_DEBUG
bool "Log filenames and checksums for loaded firmware"
- depends on CRYPTO = FW_LOADER || CRYPTO=y
depends on DYNAMIC_DEBUG
depends on FW_LOADER
default FW_LOADER
help
Select this option to use dynamic debug to log firmware filenames and
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index cb0912ea3e627..44486b2c71728 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -804,45 +804,19 @@ static void fw_abort_batch_reqs(struct firmware *fw)
fw_state_aborted(fw_priv);
mutex_unlock(&fw_lock);
}

#if defined(CONFIG_FW_LOADER_DEBUG)
-#include <crypto/hash.h>
#include <crypto/sha2.h>

static void fw_log_firmware_info(const struct firmware *fw, const char *name, struct device *device)
{
- struct shash_desc *shash;
- struct crypto_shash *alg;
- u8 *sha256buf;
- char *outbuf;
+ u8 digest[SHA256_DIGEST_SIZE];

- alg = crypto_alloc_shash("sha256", 0, 0);
- if (IS_ERR(alg))
- return;
-
- sha256buf = kmalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
- outbuf = kmalloc(SHA256_BLOCK_SIZE + 1, GFP_KERNEL);
- shash = kmalloc(sizeof(*shash) + crypto_shash_descsize(alg), GFP_KERNEL);
- if (!sha256buf || !outbuf || !shash)
- goto out_free;
-
- shash->tfm = alg;
-
- if (crypto_shash_digest(shash, fw->data, fw->size, sha256buf) < 0)
- goto out_free;
-
- for (int i = 0; i < SHA256_DIGEST_SIZE; i++)
- sprintf(&outbuf[i * 2], "%02x", sha256buf[i]);
- outbuf[SHA256_BLOCK_SIZE] = 0;
- dev_dbg(device, "Loaded FW: %s, sha256: %s\n", name, outbuf);
-
-out_free:
- kfree(shash);
- kfree(outbuf);
- kfree(sha256buf);
- crypto_free_shash(alg);
+ sha256(fw->data, fw->size, digest);
+ dev_dbg(device, "Loaded FW: %s, sha256: %*phN\n",
+ name, SHA256_DIGEST_SIZE, digest);
}
#else
static void fw_log_firmware_info(const struct firmware *fw, const char *name,
struct device *device)
{}

base-commit: 33035b665157558254b3c21c3f049fd728e72368
--
2.49.0