Re: [PATCH] firmware_loader: Add debug message with checksum for FW file

[Amadeusz Sławiński]

On 2/24/2023 1:46 PM, Greg Kroah-Hartman wrote:
> On Fri, Feb 24, 2023 at 09:19:18PM +0100, Amadeusz Sławiński wrote:
> > Enable dynamic-debug logging of firmware filenames and SHA256 checksums
> > to clearly identify the firmware files that are loaded by the system.
> >
> > Example output:
> > [   34.944619] firmware_class:_request_firmware: i915 0000:00:02.0: Loaded FW: i915/kbl_dmc_ver1_04.bin, sha256: 2cde41c3e5ad181423bcc3e98ff9c49f743c88f18646af4d0b3c3a9664b831a1
> > [   48.155884] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/cnl/dsp_basefw.bin, sha256: 43f6ac1b066e9bd0423d914960fbbdccb391af27d2b1da1085eee3ea8df0f357
> > [   49.579540] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/rt274-tplg.bin, sha256: 4b3580da96dc3d2c443ba20c6728d8b665fceb3ed57223c3a57582bbad8e2413
> > [   49.798196] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/hda-8086280c-tplg.bin, sha256: 5653172579b2be1b51fd69f5cf46e2bac8d63f2a1327924311c13b2f1fe6e601
> > [   49.859627] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/dmic-tplg.bin, sha256: 00fb7fbdb74683333400d7e46925dae60db448b88638efcca0b30215db9df63f
> >
> > Reviewed-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> > Reviewed-by: Cezary Rojewski <cezary.rojewski@xxxxxxxxx>
> > Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/base/firmware_loader/main.c | 45 ++++++++++++++++++++++++++++-
> >   1 file changed, 44 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> > index 017c4cdb219e..a6e1fb10763d 100644
> > --- a/drivers/base/firmware_loader/main.c
> > +++ b/drivers/base/firmware_loader/main.c
> > @@ -791,6 +791,47 @@ static void fw_abort_batch_reqs(struct firmware *fw)
> >   	mutex_unlock(&fw_lock);
> >   }
> >   
> > +#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
> > +#include <crypto/hash.h>
> > +#include <crypto/sha2.h>
> > +#define SHA256_STRING_SIZE (SHA256_DIGEST_SIZE * 2)
> > +static void fw_log_firmware_info(const struct firmware *fw, const char *name, struct device *device)
> > +{
> > +	char outbuf[SHA256_STRING_SIZE + 1];
> > +	u8 sha256buf[SHA256_DIGEST_SIZE];
>
> Nit, these are big, are you _SURE_ you can put them on the stack ok?
> Why not dynamically allocate them?

Well, those arrays are not that big? First one is 65 bytes and other one 
32. Although now that I looked again at the header, there is 
SHA256_BLOCK_SIZE define for string size, so I will change 
SHA256_STRING_SIZE to that instead.

> > +	struct shash_desc *shash;
> > +	struct crypto_shash *alg;
> > +
> > +	alg = crypto_alloc_shash("sha256", 0, 0);
>
> Do we need to select this in the .config as well?

Most likely.

> > +	if (!alg)
> > +		return;
> > +
> > +	shash = kmalloc(sizeof(*shash) + crypto_shash_descsize(alg), GFP_KERNEL);
>
> kmalloc_array()?

Yes.

> > +	if (!shash)
> > +		goto out_alg;
> > +
> > +	shash->tfm = alg;
> > +
> > +	if (crypto_shash_digest(shash, fw->data, fw->size, sha256buf) < 0)
> > +		goto out_shash;
> > +
> > +	for (int i = 0; i < SHA256_DIGEST_SIZE; i++)
> > +		sprintf(&outbuf[i * 2], "%02x", sha256buf[i]);
> > +	outbuf[SHA256_STRING_SIZE] = 0;
> > +	dev_dbg(device, "Loaded FW: %s, sha256: %s\n", name, outbuf);
> > +
> > +out_shash:
> > +	kfree(shash);
> > +out_alg:
> > +	crypto_free_shash(alg);
>
> Otherwise, just tiny comments, overall this looks nice, thanks for doing
> this.
>
> greg k-h