1 files changed, 342 insertions, 0 deletions
diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
new file mode 100644
index 000000000..506dd0148
--- /dev/null
+++ b/tools/hv/hv_vss_daemon.c
@@ -0,0 +1,342 @@
+/*
+ * 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);
+		}
+	}
+
+}