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From:   Tony Luck <tony.luck@intel.com>
To:     hdegoede@redhat.com, markgross@kernel.org
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        corbet@lwn.net, gregkh@linuxfoundation.org,
        andriy.shevchenko@linux.intel.com, jithu.joseph@intel.com,
        ashok.raj@intel.com, tony.luck@intel.com, rostedt@goodmis.org,
        dan.j.williams@intel.com, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        patches@lists.linux.dev, ravi.v.shankar@intel.com
Subject: [PATCH v3 06/11] platform/x86/intel/ifs: Check IFS Image sanity
Date:   Tue, 19 Apr 2022 09:38:54 -0700
Message-Id: <20220419163859.2228874-7-tony.luck@intel.com>
In-Reply-To: <20220419163859.2228874-1-tony.luck@intel.com>
References: <20220407191347.9681-1-jithu.joseph@intel.com>
 <20220419163859.2228874-1-tony.luck@intel.com>
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From: Jithu Joseph <jithu.joseph@intel.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@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>
---
 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)
+{
+	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)) {
+		dev_err(dev, "ifs header sanity check failed\n");
+		ret = -ENOENT;
+	}
+
 	release_firmware(fw);
 
 	return ret;
-- 
2.35.1