From ac8540f237280b2e302949f15d229e13477245c7 Mon Sep 17 00:00:00 2001
Message-Id: <ac8540f237280b2e302949f15d229e13477245c7@dist-git>
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 12 Dec 2017 16:23:41 +0100
Subject: [PATCH] util: introduce virHostCPUGetMicrocodeVersion

This new API reads host's CPU microcode version from /proc/cpuinfo.

Unfortunately, there is no other way of reading microcode version which
would be usable from both system and session daemon.

CVE-2017-5715

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/libvirt_private.syms |  1 +
 src/util/virhostcpu.c    | 43 +++++++++++++++++++++++++++++++++++++++++++
 src/util/virhostcpu.h    |  2 ++
 3 files changed, 46 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 85b15314a9..57999e77b0 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1861,6 +1861,7 @@ virHostCPUGetCount;
 virHostCPUGetInfo;
 virHostCPUGetKVMMaxVCPUs;
 virHostCPUGetMap;
+virHostCPUGetMicrocodeVersion;
 virHostCPUGetOnline;
 virHostCPUGetOnlineBitmap;
 virHostCPUGetPresentBitmap;
diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
index bd58aa43df..a7ae7cd4cb 100644
--- a/src/util/virhostcpu.c
+++ b/src/util/virhostcpu.c
@@ -1211,3 +1211,46 @@ virHostCPUGetKVMMaxVCPUs(void)
     return -1;
 }
 #endif /* HAVE_LINUX_KVM_H */
+
+
+#ifdef __linux__
+
+unsigned int
+virHostCPUGetMicrocodeVersion(void)
+{
+    char *outbuf = NULL;
+    char *cur;
+    unsigned int version = 0;
+
+    if (virFileReadHeaderQuiet(CPUINFO_PATH, 4096, &outbuf) < 0) {
+        char ebuf[1024];
+        VIR_DEBUG("Failed to read microcode version from %s: %s",
+                  CPUINFO_PATH, virStrerror(errno, ebuf, sizeof(ebuf)));
+        return 0;
+    }
+
+    /* Account for format 'microcode    : XXXX'*/
+    if (!(cur = strstr(outbuf, "microcode")) ||
+        !(cur = strchr(cur, ':')))
+        goto cleanup;
+    cur++;
+
+    /* Linux places the microcode revision in a 32-bit integer, so
+     * ui is fine for us too.  */
+    if (virStrToLong_ui(cur, &cur, 0, &version) < 0)
+        goto cleanup;
+
+ cleanup:
+    VIR_FREE(outbuf);
+    return version;
+}
+
+#else
+
+unsigned int
+virHostCPUGetMicrocodeVersion(void)
+{
+    return 0;
+}
+
+#endif
diff --git a/src/util/virhostcpu.h b/src/util/virhostcpu.h
index 67033de842..f9f3359288 100644
--- a/src/util/virhostcpu.h
+++ b/src/util/virhostcpu.h
@@ -66,4 +66,6 @@ virBitmapPtr virHostCPUGetSiblingsList(unsigned int cpu);
 
 int virHostCPUGetOnline(unsigned int cpu, bool *online);
 
+unsigned int virHostCPUGetMicrocodeVersion(void);
+
 #endif /* __VIR_HOSTCPU_H__*/
-- 
2.15.1