From bee1d453050075cf36cedf741986cb44cb65658c Mon Sep 17 00:00:00 2001
From: deraadt <deraadt@openbsd.org>
Date: Thu, 22 Jun 2017 15:56:29 +0000
Subject: [PATCH] calculate a "sum" based upon pointers to functions all over
 the kernel, so that an unhibernate kernel can detect if it is running with
 the kernel it booted. ok mlarkin

---
 sys/kern/subr_hibernate.c | 20 +++++++++++++++++++-
 sys/sys/hibernate.h       |  3 ++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/sys/kern/subr_hibernate.c b/sys/kern/subr_hibernate.c
index 31cff230b07..1cc4ed2f6cd 100644
--- a/sys/kern/subr_hibernate.c
+++ b/sys/kern/subr_hibernate.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_hibernate.c,v 1.121 2017/03/27 20:26:39 deraadt Exp $	*/
+/*	$OpenBSD: subr_hibernate.c,v 1.122 2017/06/22 15:56:29 deraadt Exp $	*/
 
 /*
  * Copyright (c) 2011 Ariane van der Steldt <ariane@stack.nl>
@@ -545,6 +545,17 @@ uvm_page_rle(paddr_t addr)
 	return min((pg_end - pg), HIBERNATE_CHUNK_SIZE/PAGE_SIZE);
 }
 
+/*
+ * Calculate a hopefully unique version # for this kernel, based upon
+ * how it was linked.
+ */
+u_int32_t
+hibsum(void)
+{
+	return ((long)malloc ^ (long)km_alloc ^ (long)printf ^ (long)strlen);
+}
+
+
 /*
  * Fills out the hibernate_info union pointed to by hib
  * with information about this machine (swap signature block
@@ -597,6 +608,7 @@ get_hibernate_info(union hibernate_info *hib, int suspend)
 	memset(&hib->kernel_version, 0, 128);
 	bcopy(version, &hib->kernel_version,
 	    min(strlen(version), sizeof(hib->kernel_version)-1));
+	hib->kernel_sum = hibsum();
 
 	if (suspend) {
 		/* Grab the previously-allocated piglet addresses */
@@ -927,6 +939,12 @@ hibernate_compare_signature(union hibernate_info *mine,
 		return (1);
 	}
 
+	if (hibsum() != disk->kernel_sum) {
+		DPRINTF("hibernate sum version mismatch %x %x\n",
+		    hibsum(), disk->kernel_sum);
+		return (1);
+	}
+
 	for (i = 0; i < mine->nranges; i++) {
 		if ((mine->ranges[i].base != disk->ranges[i].base) ||
 		    (mine->ranges[i].end != disk->ranges[i].end) ) {
diff --git a/sys/sys/hibernate.h b/sys/sys/hibernate.h
index b959a11dc65..ff960101f8c 100644
--- a/sys/sys/hibernate.h
+++ b/sys/sys/hibernate.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: hibernate.h,v 1.40 2016/09/27 02:53:49 dlg Exp $	*/
+/*	$OpenBSD: hibernate.h,v 1.41 2017/06/22 15:56:29 deraadt Exp $	*/
 
 /*
  * Copyright (c) 2011 Ariane van der Steldt <ariane@stack.nl>
@@ -93,6 +93,7 @@ union hibernate_info {
 		paddr_t				piglet_pa;
 		vaddr_t				piglet_va;
 		char				kernel_version[128];
+		u_int32_t			kernel_sum;
 		hibio_fn			io_func;
 		void				*io_page;
 #ifndef NO_PROPOLICE
-- 
2.20.1