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Revision 0447378a4a793da008451fad50bc0f93e9675ae6 authored by Marc Orr on 21 June 2018, 00:21:29 UTC, committed by Radim Krčmář on 22 June 2018, 14:46:26 UTC 
kvm: vmx: Nested VM-entry prereqs for event inj.
 
This patch extends the checks done prior to a nested VM entry.
Specifically, it extends the check_vmentry_prereqs function with checks
for fields relevant to the VM-entry event injection information, as
described in the Intel SDM, volume 3.

This patch is motivated by a syzkaller bug, where a bad VM-entry
interruption information field is generated in the VMCS02, which causes
the nested VM launch to fail. Then, KVM fails to resume L1.

While KVM should be improved to correctly resume L1 execution after a
failed nested launch, this change is justified because the existing code
to resume L1 is flaky/ad-hoc and the test coverage for resuming L1 is
sparse.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Marc Orr <marcorr@google.com>
[Removed comment whose parts were describing previous revisions and the
 rest was obvious from function/variable naming. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
1 parent 5f9077c
Raw File
em_nbyte.c 
/*
 * net/sched/em_nbyte.c	N-Byte ematch
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Authors:	Thomas Graf <tgraf@suug.ch>
 */

#include <linux/gfp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/tc_ematch/tc_em_nbyte.h>
#include <net/pkt_cls.h>

struct nbyte_data {
	struct tcf_em_nbyte	hdr;
	char			pattern[0];
};

static int em_nbyte_change(struct net *net, void *data, int data_len,
			   struct tcf_ematch *em)
{
	struct tcf_em_nbyte *nbyte = data;

	if (data_len < sizeof(*nbyte) ||
	    data_len < (sizeof(*nbyte) + nbyte->len))
		return -EINVAL;

	em->datalen = sizeof(*nbyte) + nbyte->len;
	em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
	if (em->data == 0UL)
		return -ENOBUFS;

	return 0;
}

static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
			  struct tcf_pkt_info *info)
{
	struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
	unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);

	ptr += nbyte->hdr.off;

	if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
		return 0;

	return !memcmp(ptr, nbyte->pattern, nbyte->hdr.len);
}

static struct tcf_ematch_ops em_nbyte_ops = {
	.kind	  = TCF_EM_NBYTE,
	.change	  = em_nbyte_change,
	.match	  = em_nbyte_match,
	.owner	  = THIS_MODULE,
	.link	  = LIST_HEAD_INIT(em_nbyte_ops.link)
};

static int __init init_em_nbyte(void)
{
	return tcf_em_register(&em_nbyte_ops);
}

static void __exit exit_em_nbyte(void)
{
	tcf_em_unregister(&em_nbyte_ops);
}

MODULE_LICENSE("GPL");

module_init(init_em_nbyte);
module_exit(exit_em_nbyte);

MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);
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