tools/hv/hv_vss_daemon.c - kernel/lockdown - Git at Google

 /*
  * 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);
 		}
 	}

 }
	/*
	* 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);
	}
	}

	}