linux-kernel - Re: [PATCH v3 06/11] platform/x86/intel/ifs: Check IFS Image sanity

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Date:   Tue, 19 Apr 2022 19:16:13 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Tony Luck <tony.luck@...el.com>
Cc:     hdegoede@...hat.com, markgross@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, corbet@....net,
        andriy.shevchenko@...ux.intel.com, jithu.joseph@...el.com,
        ashok.raj@...el.com, rostedt@...dmis.org, dan.j.williams@...el.com,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, patches@...ts.linux.dev,
        ravi.v.shankar@...el.com
Subject: Re: [PATCH v3 06/11] platform/x86/intel/ifs: Check IFS Image sanity

On Tue, Apr 19, 2022 at 09:38:54AM -0700, Tony Luck wrote:
> From: Jithu Joseph <jithu.joseph@...el.com>
> 
> IFS image is designed specifically for a given family, model and
> stepping of the processor. Like Intel microcode header, the IFS image
> has the Processor Signature, Checksum and Processor Flags that must be
> matched with the information returned by the CPUID.
> 
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
> Co-developed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  drivers/platform/x86/intel/ifs/load.c | 69 +++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
> index fa6c64707a73..b05d9055c391 100644
> --- a/drivers/platform/x86/intel/ifs/load.c
> +++ b/drivers/platform/x86/intel/ifs/load.c
> @@ -3,9 +3,73 @@
>  
>  #include <linux/firmware.h>
>  #include <linux/platform_device.h>
> +#include <asm/cpu.h>
> +#include <asm/microcode_intel.h>
>  
>  static const char *ifs_path = "intel/ifs/";
>  
> +static int ifs_sanity_check(struct device *dev, void *mc)
> +{
> +	struct microcode_header_intel *mc_header = mc;
> +	unsigned long total_size, data_size;
> +	u32 sum, i;
> +
> +	total_size = get_totalsize(mc_header);
> +	data_size = get_datasize(mc_header);
> +
> +	if ((data_size + MC_HEADER_SIZE > total_size) || (total_size % sizeof(u32))) {
> +		dev_err(dev, "bad ifs data file size.\n");
> +		return -EINVAL;
> +	}
> +
> +	if (mc_header->ldrver != 1 || mc_header->hdrver != 1) {
> +		dev_err(dev, "invalid/unknown ifs update format.\n");
> +		return -EINVAL;
> +	}
> +
> +	sum = 0;
> +	i = total_size / sizeof(u32);
> +	while (i--)
> +		sum += ((u32 *)mc)[i];
> +
> +	if (sum) {
> +		dev_err(dev, "bad ifs data checksum, aborting.\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static bool find_ifs_matching_signature(struct device *dev, struct ucode_cpu_info *uci, void *mc)
> +{
> +	struct microcode_header_intel *shdr;
> +	unsigned int mc_size;
> +
> +	shdr = (struct microcode_header_intel *)mc;
> +	mc_size = get_totalsize(shdr);
> +
> +	if (!mc_size || ifs_sanity_check(dev, shdr) < 0) {
> +		dev_err(dev, "ifs sanity check failure\n");
> +		return false;
> +	}
> +
> +	if (!intel_cpu_signatures_match(uci->cpu_sig.sig, uci->cpu_sig.pf, shdr->sig, shdr->pf)) {
> +		dev_err(dev, "ifs signature, pf not matching\n");
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static bool ifs_image_sanity_check(struct device *dev, void *data)

u8 *data?

> +{
> +	struct ucode_cpu_info uci;
> +
> +	intel_cpu_collect_info_early(&uci);
> +
> +	return find_ifs_matching_signature(dev, &uci, data);
> +}
> +
>  /*
>   * Load ifs image. Before loading ifs module, the ifs image must be located
>   * in /lib/firmware/intel/ifs and named as {family/model/stepping}.{testname}.
> @@ -25,6 +89,11 @@ int load_ifs_binary(struct device *dev)
>  		return ret;
>  	}
>  
> +	if (!ifs_image_sanity_check(dev, (void *)fw->data)) {

It's not a void pointer, it's a pointer to u8.  Why cast it away?

thanks,

greg k-h