1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21#include <sys/types.h>
22#include <sys/socket.h>
23#include <sys/poll.h>
24#include <sys/ioctl.h>
25#include <fcntl.h>
26#include <stdio.h>
27#include <mntent.h>
28#include <stdlib.h>
29#include <unistd.h>
30#include <string.h>
31#include <ctype.h>
32#include <errno.h>
33#include <arpa/inet.h>
34#include <linux/fs.h>
35#include <linux/connector.h>
36#include <linux/hyperv.h>
37#include <linux/netlink.h>
38#include <syslog.h>
39
40static struct sockaddr_nl addr;
41
42#ifndef SOL_NETLINK
43#define SOL_NETLINK 270
44#endif
45
46
47static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op)
48{
49 int ret, fd = open(dir, O_RDONLY);
50
51 if (fd < 0)
52 return 1;
53 ret = ioctl(fd, cmd, 0);
54 syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno));
55 close(fd);
56 return !!ret;
57}
58
59static int vss_operate(int operation)
60{
61 char *fs_op;
62 char match[] = "/dev/";
63 FILE *mounts;
64 struct mntent *ent;
65 unsigned int cmd;
66 int error = 0, root_seen = 0;
67
68 switch (operation) {
69 case VSS_OP_FREEZE:
70 cmd = FIFREEZE;
71 fs_op = "freeze";
72 break;
73 case VSS_OP_THAW:
74 cmd = FITHAW;
75 fs_op = "thaw";
76 break;
77 default:
78 return -1;
79 }
80
81 mounts = setmntent("/proc/mounts", "r");
82 if (mounts == NULL)
83 return -1;
84
85 while ((ent = getmntent(mounts))) {
86 if (strncmp(ent->mnt_fsname, match, strlen(match)))
87 continue;
88 if (strcmp(ent->mnt_type, "iso9660") == 0)
89 continue;
90 if (strcmp(ent->mnt_type, "vfat") == 0)
91 continue;
92 if (strcmp(ent->mnt_dir, "/") == 0) {
93 root_seen = 1;
94 continue;
95 }
96 error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op);
97 }
98 endmntent(mounts);
99
100 if (root_seen) {
101 error |= vss_do_freeze("/", cmd, fs_op);
102 }
103
104 return error;
105}
106
107static int netlink_send(int fd, struct cn_msg *msg)
108{
109 struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE };
110 unsigned int size;
111 struct msghdr message;
112 struct iovec iov[2];
113
114 size = sizeof(struct cn_msg) + msg->len;
115
116 nlh.nlmsg_pid = getpid();
117 nlh.nlmsg_len = NLMSG_LENGTH(size);
118
119 iov[0].iov_base = &nlh;
120 iov[0].iov_len = sizeof(nlh);
121
122 iov[1].iov_base = msg;
123 iov[1].iov_len = size;
124
125 memset(&message, 0, sizeof(message));
126 message.msg_name = &addr;
127 message.msg_namelen = sizeof(addr);
128 message.msg_iov = iov;
129 message.msg_iovlen = 2;
130
131 return sendmsg(fd, &message, 0);
132}
133
134int main(void)
135{
136 int fd, len, nl_group;
137 int error;
138 struct cn_msg *message;
139 struct pollfd pfd;
140 struct nlmsghdr *incoming_msg;
141 struct cn_msg *incoming_cn_msg;
142 int op;
143 struct hv_vss_msg *vss_msg;
144 char *vss_recv_buffer;
145 size_t vss_recv_buffer_len;
146
147 if (daemon(1, 0))
148 return 1;
149
150 openlog("Hyper-V VSS", 0, LOG_USER);
151 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
152
153 vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
154 vss_recv_buffer = calloc(1, vss_recv_buffer_len);
155 if (!vss_recv_buffer) {
156 syslog(LOG_ERR, "Failed to allocate netlink buffers");
157 exit(EXIT_FAILURE);
158 }
159
160 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
161 if (fd < 0) {
162 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s",
163 errno, strerror(errno));
164 exit(EXIT_FAILURE);
165 }
166 addr.nl_family = AF_NETLINK;
167 addr.nl_pad = 0;
168 addr.nl_pid = 0;
169 addr.nl_groups = 0;
170
171
172 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
173 if (error < 0) {
174 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno));
175 close(fd);
176 exit(EXIT_FAILURE);
177 }
178 nl_group = CN_VSS_IDX;
179 if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) {
180 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno));
181 close(fd);
182 exit(EXIT_FAILURE);
183 }
184
185
186
187 message = (struct cn_msg *)vss_recv_buffer;
188 message->id.idx = CN_VSS_IDX;
189 message->id.val = CN_VSS_VAL;
190 message->ack = 0;
191 vss_msg = (struct hv_vss_msg *)message->data;
192 vss_msg->vss_hdr.operation = VSS_OP_REGISTER;
193
194 message->len = sizeof(struct hv_vss_msg);
195
196 len = netlink_send(fd, message);
197 if (len < 0) {
198 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno));
199 close(fd);
200 exit(EXIT_FAILURE);
201 }
202
203 pfd.fd = fd;
204
205 while (1) {
206 struct sockaddr *addr_p = (struct sockaddr *) &addr;
207 socklen_t addr_l = sizeof(addr);
208 pfd.events = POLLIN;
209 pfd.revents = 0;
210
211 if (poll(&pfd, 1, -1) < 0) {
212 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
213 if (errno == EINVAL) {
214 close(fd);
215 exit(EXIT_FAILURE);
216 }
217 else
218 continue;
219 }
220
221 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0,
222 addr_p, &addr_l);
223
224 if (len < 0) {
225 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
226 addr.nl_pid, errno, strerror(errno));
227 close(fd);
228 return -1;
229 }
230
231 if (addr.nl_pid) {
232 syslog(LOG_WARNING,
233 "Received packet from untrusted pid:%u",
234 addr.nl_pid);
235 continue;
236 }
237
238 incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
239
240 if (incoming_msg->nlmsg_type != NLMSG_DONE)
241 continue;
242
243 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
244 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
245 op = vss_msg->vss_hdr.operation;
246 error = HV_S_OK;
247
248 switch (op) {
249 case VSS_OP_FREEZE:
250 case VSS_OP_THAW:
251 error = vss_operate(op);
252 if (error)
253 error = HV_E_FAIL;
254 break;
255 default:
256 syslog(LOG_ERR, "Illegal op:%d\n", op);
257 }
258 vss_msg->error = error;
259 len = netlink_send(fd, incoming_cn_msg);
260 if (len < 0) {
261 syslog(LOG_ERR, "net_link send failed; error:%d %s",
262 errno, strerror(errno));
263 exit(EXIT_FAILURE);
264 }
265 }
266
267}
268
