/*
* 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 <sys/ioctl.h>
#include <fcntl.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/fs.h>
#include <linux/connector.h>
#include <linux/hyperv.h>
#include <linux/netlink.h>
#include <syslog.h>
#include <getopt.h>
static struct sockaddr_nl addr;
#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif
/* Don't use syslog() in the function since that can cause write to disk */
static int vss_do_freeze(char *dir, unsigned int cmd)
{
int ret, fd = open(dir, O_RDONLY);
if (fd < 0)
return 1;
ret = ioctl(fd, cmd, 0);
/*
* If a partition is mounted more than once, only the first
* FREEZE/THAW can succeed and the later ones will get
* EBUSY/EINVAL respectively: there could be 2 cases:
* 1) a user may mount the same partition to differnt directories
* by mistake or on purpose;
* 2) The subvolume of btrfs appears to have the same partition
* mounted more than once.
*/
if (ret) {
if ((cmd == FIFREEZE && errno == EBUSY) ||
(cmd == FITHAW && errno == EINVAL)) {
close(fd);
return 0;
}
}
close(fd);
return !!ret;
}
static int vss_operate(int operation)
{
char match[] = "/dev/";
FILE *mounts;
struct mntent *ent;
char errdir[1024] = {0};
unsigned int cmd;
int error = 0, root_seen = 0, save_errno = 0;
switch (operation) {
case VSS_OP_FREEZE:
cmd = FIFREEZE;
break;
case VSS_OP_THAW:
cmd = FITHAW;
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 (hasmntopt(ent, MNTOPT_RO) != NULL)
continue;
if (strcmp(ent->mnt_type, "vfat") == 0)
continue;
if (strcmp(ent->mnt_dir, "/") == 0) {
root_seen = 1;
continue;
}
error |= vss_do_freeze(ent->mnt_dir, cmd);
if (error && operation == VSS_OP_FREEZE)
goto err;
}
endmntent(mounts);
if (root_seen) {
error |= vss_do_freeze("/", cmd);
if (error && operation == VSS_OP_FREEZE)
goto err;
}
goto out;
err:
save_errno = errno;
if (ent) {
strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
endmntent(mounts);
}
vss_operate(VSS_OP_THAW);
/* Call syslog after we thaw all filesystems */
if (ent)
syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
errdir, save_errno, strerror(save_errno));
else
syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
strerror(save_errno));
out:
return error;
}
static int netlink_send(int fd, struct cn_msg *msg)
{
struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE };
unsigned int size;
struct msghdr message;
struct iovec iov[2];
size = sizeof(struct cn_msg) + msg->len;
nlh.nlmsg_pid = getpid();
nlh.nlmsg_len = NLMSG_LENGTH(size);
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);
}
void print_usage(char *argv[])
{
fprintf(stderr, "Usage: %s [options]\n"
"Options are:\n"
" -n, --no-daemon stay in foreground, don't daemonize\n"
" -h, --help print this help\n", argv[0]);
}
int main(int argc, char *argv[])
{
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;
char *vss_recv_buffer;
size_t vss_recv_buffer_len;
int daemonize = 1, long_index = 0, opt;
static struct option long_options[] = {
{"help", no_argument, 0, 'h' },
{"no-daemon", no_argument, 0, 'n' },
{0, 0, 0, 0 }
};
while ((opt = getopt_long(argc, argv, "hn", long_options,
&long_index)) != -1) {
switch (opt) {
case 'n':
daemonize = 0;
break;
case 'h':
default:
print_usage(argv);
exit(EXIT_FAILURE);
}
}
if (daemonize && daemon(1, 0))
return 1;
openlog("Hyper-V VSS", 0, LOG_USER);
syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
vss_recv_buffer = calloc(1, vss_recv_buffer_len);
if (!vss_recv_buffer) {
syslog(LOG_ERR, "Failed to allocate netlink buffers");
exit(EXIT_FAILURE);
}
fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
if (fd < 0) {
syslog(LOG_ERR, "netlink socket creation failed; error:%d %s",
errno, strerror(errno));
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 %s", errno, strerror(errno));
close(fd);
exit(EXIT_FAILURE);
}
nl_group = CN_VSS_IDX;
if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) {
syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno));
close(fd);
exit(EXIT_FAILURE);
}
/*
* Register ourselves with the kernel.
*/
message = (struct cn_msg *)vss_recv_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 %s", errno, strerror(errno));
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;
if (poll(&pfd, 1, -1) < 0) {
syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
if (errno == EINVAL) {
close(fd);
exit(EXIT_FAILURE);
}
else
continue;
}
len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 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);
syslog(LOG_INFO, "VSS: op=%s: %s\n",
op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
error ? "failed" : "succeeded");
if (error) {
error = HV_E_FAIL;
syslog(LOG_ERR, "op=%d failed!", op);
syslog(LOG_ERR, "report it with these files:");
syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
}
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 %s",
errno, strerror(errno));
exit(EXIT_FAILURE);
}
}
}
