platform/x86/intel/ifs: Check IFS Image sanity

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@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220506225410.1652287-7-tony.luck@intel.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel/ifs/load.c

@@ -2,9 +2,72 @@
 /* Copyright(c) 2022 Intel Corporation. */
 
 #include <linux/firmware.h>
+#include <asm/cpu.h>
+#include <asm/microcode_intel.h>
 
 #include "ifs.h"
 
+static int ifs_sanity_check(struct device *dev,
+			    const struct microcode_header_intel *mc_header)
+{
+	unsigned long total_size, data_size;
+	u32 sum, *mc;
+
+	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;
+	}
+
+	mc = (u32 *)mc_header;
+	sum = 0;
+	for (int i = 0; i < total_size / sizeof(u32); i++)
+		sum += 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,
+					const struct microcode_header_intel *shdr)
+{
+	unsigned int mc_size;
+
+	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, const struct microcode_header_intel *data)
+{
+	struct ucode_cpu_info uci;
+
+	intel_cpu_collect_info(&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}.
@@ -24,5 +87,8 @@ void ifs_load_firmware(struct device *dev)
 		return;
 	}
 
+	if (!ifs_image_sanity_check(dev, (struct microcode_header_intel *)fw->data))
+		dev_err(dev, "ifs header sanity check failed\n");
+
 	release_firmware(fw);
 }