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
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
audit_fsnotify.c
/* audit_fsnotify.c -- tracking inodes
*
* Copyright 2003-2009,2014-2015 Red Hat, Inc.
* Copyright 2005 Hewlett-Packard Development Company, L.P.
* Copyright 2005 IBM Corporation
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/audit.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/fsnotify_backend.h>
#include <linux/namei.h>
#include <linux/netlink.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include "audit.h"
/*
* this mark lives on the parent directory of the inode in question.
* but dev, ino, and path are about the child
*/
struct audit_fsnotify_mark {
dev_t dev; /* associated superblock device */
unsigned long ino; /* associated inode number */
char *path; /* insertion path */
struct fsnotify_mark mark; /* fsnotify mark on the inode */
struct audit_krule *rule;
};
/* fsnotify handle. */
static struct fsnotify_group *audit_fsnotify_group;
/* fsnotify events we care about. */
#define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
FS_MOVE_SELF | FS_EVENT_ON_CHILD)
static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
{
kfree(audit_mark->path);
kfree(audit_mark);
}
static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
{
struct audit_fsnotify_mark *audit_mark;
audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
audit_fsnotify_mark_free(audit_mark);
}
char *audit_mark_path(struct audit_fsnotify_mark *mark)
{
return mark->path;
}
int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
{
if (mark->ino == AUDIT_INO_UNSET)
return 0;
return (mark->ino == ino) && (mark->dev == dev);
}
static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
const struct inode *inode)
{
audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
}
struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
{
struct audit_fsnotify_mark *audit_mark;
struct path path;
struct dentry *dentry;
struct inode *inode;
int ret;
if (pathname[0] != '/' || pathname[len-1] == '/')
return ERR_PTR(-EINVAL);
dentry = kern_path_locked(pathname, &path);
if (IS_ERR(dentry))
return (void *)dentry; /* returning an error */
inode = path.dentry->d_inode;
inode_unlock(inode);
audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
if (unlikely(!audit_mark)) {
audit_mark = ERR_PTR(-ENOMEM);
goto out;
}
fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
audit_mark->mark.mask = AUDIT_FS_EVENTS;
audit_mark->path = pathname;
audit_update_mark(audit_mark, dentry->d_inode);
audit_mark->rule = krule;
ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
if (ret < 0) {
fsnotify_put_mark(&audit_mark->mark);
audit_mark = ERR_PTR(ret);
}
out:
dput(dentry);
path_put(&path);
return audit_mark;
}
static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
{
struct audit_buffer *ab;
struct audit_krule *rule = audit_mark->rule;
if (!audit_enabled)
return;
ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
if (unlikely(!ab))
return;
audit_log_format(ab, "auid=%u ses=%u op=%s",
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current), op);
audit_log_format(ab, " path=");
audit_log_untrustedstring(ab, audit_mark->path);
audit_log_key(ab, rule->filterkey);
audit_log_format(ab, " list=%d res=1", rule->listnr);
audit_log_end(ab);
}
void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
{
fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
fsnotify_put_mark(&audit_mark->mark);
}
void audit_remove_mark_rule(struct audit_krule *krule)
{
struct audit_fsnotify_mark *mark = krule->exe;
audit_remove_mark(mark);
}
static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
{
struct audit_krule *rule = audit_mark->rule;
struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
audit_mark_log_rule_change(audit_mark, "autoremove_rule");
audit_del_rule(entry);
}
/* Update mark data in audit rules based on fsnotify events. */
static int audit_mark_handle_event(struct fsnotify_group *group,
struct inode *to_tell,
u32 mask, const void *data, int data_type,
const unsigned char *dname, u32 cookie,
struct fsnotify_iter_info *iter_info)
{
struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
struct audit_fsnotify_mark *audit_mark;
const struct inode *inode = NULL;
audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
BUG_ON(group != audit_fsnotify_group);
switch (data_type) {
case (FSNOTIFY_EVENT_PATH):
inode = ((const struct path *)data)->dentry->d_inode;
break;
case (FSNOTIFY_EVENT_INODE):
inode = (const struct inode *)data;
break;
default:
BUG();
return 0;
}
if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
return 0;
audit_update_mark(audit_mark, inode);
} else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
audit_autoremove_mark_rule(audit_mark);
return 0;
}
static const struct fsnotify_ops audit_mark_fsnotify_ops = {
.handle_event = audit_mark_handle_event,
.free_mark = audit_fsnotify_free_mark,
};
static int __init audit_fsnotify_init(void)
{
audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
if (IS_ERR(audit_fsnotify_group)) {
audit_fsnotify_group = NULL;
audit_panic("cannot create audit fsnotify group");
}
return 0;
}
device_initcall(audit_fsnotify_init);
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