/* * An implementation of the host initiated guest snapshot for Hyper-V. * * * Copyright (C) 2013, Microsoft, Inc. * Author : K. Y. Srinivasan * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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_do_freeze(char *dir, unsigned int cmd, char *fs_op) { 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)); close(fd); return !!ret; } static int vss_operate(int operation) { char *fs_op; char match[] = "/dev/"; FILE *mounts; struct mntent *ent; unsigned int cmd; int error = 0, root_seen = 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; } 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_type, "iso9660") == 0) continue; if (strcmp(ent->mnt_dir, "/") == 0) { root_seen = 1; continue; } error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op); } endmntent(mounts); if (root_seen) { error |= vss_do_freeze("/", cmd, fs_op); } 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); } } }