1 files changed, 229 insertions, 123 deletions

diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index fea03a3edaf4..dd111870beee 100644
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -1,28 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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 <linux/types.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <mntent.h>
@@ -31,51 +20,113 @@
 #include <string.h>
 #include <ctype.h>
 #include <errno.h>
-#include <arpa/inet.h>
 #include <linux/fs.h>
-#include <linux/connector.h>
+#include <linux/major.h>
 #include <linux/hyperv.h>
-#include <linux/netlink.h>
 #include <syslog.h>
+#include <getopt.h>
+#include <stdbool.h>
+#include <dirent.h>
 
-static char vss_recv_buffer[4096];
-static char vss_send_buffer[4096];
-static struct sockaddr_nl addr;
+static bool fs_frozen;
 
-#ifndef SOL_NETLINK
-#define SOL_NETLINK 270
-#endif
-
-
-static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op)
+/* 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);
-	syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno));
+
+	/*
+	 * 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 different 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 bool is_dev_loop(const char *blkname)
+{
+	char *buffer;
+	DIR *dir;
+	struct dirent *entry;
+	bool ret = false;
+
+	buffer = malloc(PATH_MAX);
+	if (!buffer) {
+		syslog(LOG_ERR, "Can't allocate memory!");
+		exit(1);
+	}
+
+	snprintf(buffer, PATH_MAX, "%s/loop", blkname);
+	if (!access(buffer, R_OK | X_OK)) {
+		ret = true;
+		goto free_buffer;
+	} else if (errno != ENOENT) {
+		syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
+		       buffer, errno, strerror(errno));
+	}
+
+	snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
+	dir = opendir(buffer);
+	if (!dir) {
+		if (errno != ENOENT)
+			syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
+			       buffer, errno, strerror(errno));
+		goto free_buffer;
+	}
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strcmp(entry->d_name, ".") == 0 ||
+		    strcmp(entry->d_name, "..") == 0)
+			continue;
+
+		snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
+			 entry->d_name);
+		if (is_dev_loop(buffer)) {
+			ret = true;
+			break;
+		}
+	}
+	closedir(dir);
+free_buffer:
+	free(buffer);
+	return ret;
+}
+
 static int vss_operate(int operation)
 {
-	char *fs_op;
 	char match[] = "/dev/";
 	FILE *mounts;
 	struct mntent *ent;
+	struct stat sb;
+	char errdir[1024] = {0};
+	char blkdir[23]; /* /sys/dev/block/XXX:XXX */
 	unsigned int cmd;
-	int error = 0, root_seen = 0;
+	int error = 0, root_seen = 0, save_errno = 0;
 
 	switch (operation) {
 	case VSS_OP_FREEZE:
 		cmd = FIFREEZE;
-		fs_op = "freeze";
 		break;
 	case VSS_OP_THAW:
 		cmd = FITHAW;
-		fs_op = "thaw";
 		break;
 	default:
 		return -1;
@@ -88,143 +139,178 @@ static int vss_operate(int operation)
 	while ((ent = getmntent(mounts))) {
 		if (strncmp(ent->mnt_fsname, match, strlen(match)))
 			continue;
-		if (strcmp(ent->mnt_type, "iso9660") == 0)
+		if (stat(ent->mnt_fsname, &sb)) {
+			syslog(LOG_ERR, "Can't stat: %s; error:%d %s!",
+			       ent->mnt_fsname, errno, strerror(errno));
+		} else {
+			sprintf(blkdir, "/sys/dev/block/%d:%d",
+				major(sb.st_rdev), minor(sb.st_rdev));
+			if (is_dev_loop(blkdir))
+				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, fs_op);
+		error |= vss_do_freeze(ent->mnt_dir, cmd);
+		if (operation == VSS_OP_FREEZE) {
+			if (error)
+				goto err;
+			fs_frozen = true;
+		}
 	}
+
 	endmntent(mounts);
 
 	if (root_seen) {
-		error |= vss_do_freeze("/", cmd, fs_op);
+		error |= vss_do_freeze("/", cmd);
+		if (operation == VSS_OP_FREEZE) {
+			if (error)
+				goto err;
+			fs_frozen = true;
+		}
 	}
 
+	if (operation == VSS_OP_THAW && !error)
+		fs_frozen = false;
+
+	goto out;
+err:
+	save_errno = errno;
+	if (ent) {
+		strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
+		endmntent(mounts);
+	}
+	vss_operate(VSS_OP_THAW);
+	fs_frozen = false;
+	/* 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)
+void print_usage(char *argv[])
 {
-	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);
+	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(void)
+int main(int argc, char *argv[])
 {
-	int fd, len, nl_group;
+	int vss_fd = -1, len;
 	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;
+	struct hv_vss_msg vss_msg[1];
+	int daemonize = 1, long_index = 0, opt;
+	int in_handshake;
+	__u32 kernel_modver;
+
+	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':
+			print_usage(argv);
+			exit(0);
+		default:
+			print_usage(argv);
+			exit(EXIT_FAILURE);
+		}
+	}
 
-	if (daemon(1, 0))
+	if (daemonize && 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);
+reopen_vss_fd:
+	if (vss_fd != -1)
+		close(vss_fd);
+	if (fs_frozen) {
+		if (vss_operate(VSS_OP_THAW) || fs_frozen) {
+			syslog(LOG_ERR, "failed to thaw file system: err=%d",
+			       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", error);
-		close(fd);
+	in_handshake = 1;
+	vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
+	if (vss_fd < 0) {
+		syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
+		       errno, strerror(errno));
 		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);
+	vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
 
-	len = netlink_send(fd, message);
+	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
 	if (len < 0) {
-		syslog(LOG_ERR, "netlink_send failed; error:%d", len);
-		close(fd);
+		syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
+		       errno, strerror(errno));
+		close(vss_fd);
 		exit(EXIT_FAILURE);
 	}
 
-	pfd.fd = fd;
+	pfd.fd = vss_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 (poll(&pfd, 1, -1) < 0) {
+			syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
+			if (errno == EINVAL) {
+				close(vss_fd);
+				exit(EXIT_FAILURE);
+			}
+			else
+				continue;
 		}
 
-		if (addr.nl_pid) {
-			syslog(LOG_WARNING,
-				"Received packet from untrusted pid:%u",
-				addr.nl_pid);
+		len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
+
+		if (in_handshake) {
+			if (len != sizeof(kernel_modver)) {
+				syslog(LOG_ERR, "invalid version negotiation");
+				exit(EXIT_FAILURE);
+			}
+			kernel_modver = *(__u32 *)vss_msg;
+			in_handshake = 0;
+			syslog(LOG_INFO, "VSS: kernel module version: %d",
+			       kernel_modver);
 			continue;
 		}
 
-		incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
-
-		if (incoming_msg->nlmsg_type != NLMSG_DONE)
-			continue;
+		if (len != sizeof(struct hv_vss_msg)) {
+			syslog(LOG_ERR, "read failed; error:%d %s",
+			       errno, strerror(errno));
+			goto reopen_vss_fd;
+		}
 
-		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;
 
@@ -232,18 +318,38 @@ int main(void)
 		case VSS_OP_FREEZE:
 		case VSS_OP_THAW:
 			error = vss_operate(op);
-			if (error)
+			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;
+		case VSS_OP_HOT_BACKUP:
+			syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
 			break;
 		default:
 			syslog(LOG_ERR, "Illegal op:%d\n", op);
 		}
+
+		/*
+		 * The write() may return an error due to the faked VSS_OP_THAW
+		 * message upon hibernation. Ignore the error by resetting the
+		 * dev file, i.e. closing and re-opening it.
+		 */
 		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);
+		len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
+		if (len != sizeof(struct hv_vss_msg)) {
+			syslog(LOG_ERR, "write failed; error: %d %s", errno,
+			       strerror(errno));
+			goto reopen_vss_fd;
 		}
 	}
 
+	close(vss_fd);
+	exit(0);
 }