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/*
* An implementation of the host initiated guest snapshot for Hyper-V.
*
*
* Copyright (C) 2013, Microsoft, Inc.
* Author : K. Y. Srinivasan <kys@microsoft.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for more
* details.
*
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <linux/types.h>
#include <stdio.h>
#include <mntent.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <arpa/inet.h>
#include <linux/connector.h>
#include <linux/hyperv.h>
#include <linux/netlink.h>
#include <syslog.h>
static char vss_recv_buffer[4096];
static char vss_send_buffer[4096];
static struct sockaddr_nl addr;
#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif
static int vss_operate(int operation)
{
char *fs_op;
char cmd[512];
char match[] = "/dev/";
FILE *mounts;
struct mntent *ent;
int error = 0, root_seen = 0;
switch (operation) {
case VSS_OP_FREEZE:
fs_op = "-f ";
break;
case VSS_OP_THAW:
fs_op = "-u ";
break;
default:
return -1;
}
mounts = setmntent("/proc/mounts", "r");
if (mounts == NULL)
return -1;
while((ent = getmntent(mounts))) {
if (strncmp(ent->mnt_fsname, match, strlen(match)))
continue;
if (strcmp(ent->mnt_dir, "/") == 0) {
root_seen = 1;
continue;
}
snprintf(cmd, sizeof(cmd), "fsfreeze %s '%s'", fs_op, ent->mnt_dir);
syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
error |= system(cmd);
}
endmntent(mounts);
if (root_seen) {
sprintf(cmd, "fsfreeze %s /", fs_op);
syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
error |= system(cmd);
}
return error;
}
static int netlink_send(int fd, struct cn_msg *msg)
{
struct nlmsghdr *nlh;
unsigned int size;
struct msghdr message;
char buffer[64];
struct iovec iov[2];
size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len);
nlh = (struct nlmsghdr *)buffer;
nlh->nlmsg_seq = 0;
nlh->nlmsg_pid = getpid();
nlh->nlmsg_type = NLMSG_DONE;
nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh));
nlh->nlmsg_flags = 0;
iov[0].iov_base = nlh;
iov[0].iov_len = sizeof(*nlh);
iov[1].iov_base = msg;
iov[1].iov_len = size;
memset(&message, 0, sizeof(message));
message.msg_name = &addr;
message.msg_namelen = sizeof(addr);
message.msg_iov = iov;
message.msg_iovlen = 2;
return sendmsg(fd, &message, 0);
}
int main(void)
{
int fd, len, nl_group;
int error;
struct cn_msg *message;
struct pollfd pfd;
struct nlmsghdr *incoming_msg;
struct cn_msg *incoming_cn_msg;
int op;
struct hv_vss_msg *vss_msg;
if (daemon(1, 0))
return 1;
openlog("Hyper-V VSS", 0, LOG_USER);
syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
if (fd < 0) {
syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd);
exit(EXIT_FAILURE);
}
addr.nl_family = AF_NETLINK;
addr.nl_pad = 0;
addr.nl_pid = 0;
addr.nl_groups = 0;
error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
if (error < 0) {
syslog(LOG_ERR, "bind failed; error:%d", error);
close(fd);
exit(EXIT_FAILURE);
}
nl_group = CN_VSS_IDX;
setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group));
/*
* Register ourselves with the kernel.
*/
message = (struct cn_msg *)vss_send_buffer;
message->id.idx = CN_VSS_IDX;
message->id.val = CN_VSS_VAL;
message->ack = 0;
vss_msg = (struct hv_vss_msg *)message->data;
vss_msg->vss_hdr.operation = VSS_OP_REGISTER;
message->len = sizeof(struct hv_vss_msg);
len = netlink_send(fd, message);
if (len < 0) {
syslog(LOG_ERR, "netlink_send failed; error:%d", len);
close(fd);
exit(EXIT_FAILURE);
}
pfd.fd = fd;
while (1) {
struct sockaddr *addr_p = (struct sockaddr *) &addr;
socklen_t addr_l = sizeof(addr);
pfd.events = POLLIN;
pfd.revents = 0;
poll(&pfd, 1, -1);
len = recvfrom(fd, vss_recv_buffer, sizeof(vss_recv_buffer), 0,
addr_p, &addr_l);
if (len < 0) {
syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
addr.nl_pid, errno, strerror(errno));
close(fd);
return -1;
}
if (addr.nl_pid) {
syslog(LOG_WARNING,
"Received packet from untrusted pid:%u",
addr.nl_pid);
continue;
}
incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
if (incoming_msg->nlmsg_type != NLMSG_DONE)
continue;
incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
op = vss_msg->vss_hdr.operation;
error = HV_S_OK;
switch (op) {
case VSS_OP_FREEZE:
case VSS_OP_THAW:
error = vss_operate(op);
if (error)
error = HV_E_FAIL;
break;
default:
syslog(LOG_ERR, "Illegal op:%d\n", op);
}
vss_msg->error = error;
len = netlink_send(fd, incoming_cn_msg);
if (len < 0) {
syslog(LOG_ERR, "net_link send failed; error:%d", len);
exit(EXIT_FAILURE);
}
}
}
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