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1 | /* | |
2 | * Helper for QEMU Proxy FS Driver | |
3 | * Copyright IBM, Corp. 2011 | |
4 | * | |
5 | * Authors: | |
6 | * M. Mohan Kumar <mohan@in.ibm.com> | |
7 | * | |
8 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
9 | * the COPYING file in the top-level directory. | |
10 | */ | |
11 | ||
12 | /* | |
13 | * NOTE: The 9p 'proxy' backend is deprecated (since QEMU 8.1) and will be | |
14 | * removed in a future version of QEMU! | |
15 | */ | |
16 | ||
17 | #include "qemu/osdep.h" | |
18 | #include <glib/gstdio.h> | |
19 | #include <sys/resource.h> | |
20 | #include <getopt.h> | |
21 | #include <syslog.h> | |
22 | #include <sys/fsuid.h> | |
23 | #include <sys/vfs.h> | |
24 | #include <sys/ioctl.h> | |
25 | #include <linux/fs.h> | |
26 | #ifdef CONFIG_LINUX_MAGIC_H | |
27 | #include <linux/magic.h> | |
28 | #endif | |
29 | #include <cap-ng.h> | |
30 | #include "qemu/sockets.h" | |
31 | #include "qemu/xattr.h" | |
32 | #include "9p-iov-marshal.h" | |
33 | #include "hw/9pfs/9p-proxy.h" | |
34 | #include "hw/9pfs/9p-util.h" | |
35 | #include "fsdev/9p-iov-marshal.h" | |
36 | ||
37 | #define PROGNAME "virtfs-proxy-helper" | |
38 | ||
39 | #ifndef XFS_SUPER_MAGIC | |
40 | #define XFS_SUPER_MAGIC 0x58465342 | |
41 | #endif | |
42 | #ifndef EXT2_SUPER_MAGIC | |
43 | #define EXT2_SUPER_MAGIC 0xEF53 | |
44 | #endif | |
45 | #ifndef REISERFS_SUPER_MAGIC | |
46 | #define REISERFS_SUPER_MAGIC 0x52654973 | |
47 | #endif | |
48 | #ifndef BTRFS_SUPER_MAGIC | |
49 | #define BTRFS_SUPER_MAGIC 0x9123683E | |
50 | #endif | |
51 | ||
52 | static const struct option helper_opts[] = { | |
53 | {"fd", required_argument, NULL, 'f'}, | |
54 | {"path", required_argument, NULL, 'p'}, | |
55 | {"nodaemon", no_argument, NULL, 'n'}, | |
56 | {"socket", required_argument, NULL, 's'}, | |
57 | {"uid", required_argument, NULL, 'u'}, | |
58 | {"gid", required_argument, NULL, 'g'}, | |
59 | {}, | |
60 | }; | |
61 | ||
62 | static bool is_daemon; | |
63 | static bool get_version; /* IOC getversion IOCTL supported */ | |
64 | static char *prog_name; | |
65 | ||
66 | static void G_GNUC_PRINTF(2, 3) do_log(int loglevel, const char *format, ...) | |
67 | { | |
68 | va_list ap; | |
69 | ||
70 | va_start(ap, format); | |
71 | if (is_daemon) { | |
72 | vsyslog(LOG_CRIT, format, ap); | |
73 | } else { | |
74 | vfprintf(stderr, format, ap); | |
75 | } | |
76 | va_end(ap); | |
77 | } | |
78 | ||
79 | static void do_perror(const char *string) | |
80 | { | |
81 | if (is_daemon) { | |
82 | syslog(LOG_CRIT, "%s:%s", string, strerror(errno)); | |
83 | } else { | |
84 | fprintf(stderr, "%s:%s\n", string, strerror(errno)); | |
85 | } | |
86 | } | |
87 | ||
88 | static int init_capabilities(void) | |
89 | { | |
90 | /* helper needs following capabilities only */ | |
91 | int cap_list[] = { | |
92 | CAP_CHOWN, | |
93 | CAP_DAC_OVERRIDE, | |
94 | CAP_FOWNER, | |
95 | CAP_FSETID, | |
96 | CAP_SETGID, | |
97 | CAP_MKNOD, | |
98 | CAP_SETUID, | |
99 | }; | |
100 | int i; | |
101 | ||
102 | capng_clear(CAPNG_SELECT_BOTH); | |
103 | for (i = 0; i < ARRAY_SIZE(cap_list); i++) { | |
104 | if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED, | |
105 | cap_list[i]) < 0) { | |
106 | do_perror("capng_update"); | |
107 | return -1; | |
108 | } | |
109 | } | |
110 | if (capng_apply(CAPNG_SELECT_BOTH) < 0) { | |
111 | do_perror("capng_apply"); | |
112 | return -1; | |
113 | } | |
114 | ||
115 | /* Prepare effective set for setugid. */ | |
116 | for (i = 0; i < ARRAY_SIZE(cap_list); i++) { | |
117 | if (cap_list[i] == CAP_DAC_OVERRIDE) { | |
118 | continue; | |
119 | } | |
120 | ||
121 | if (capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, | |
122 | cap_list[i]) < 0) { | |
123 | do_perror("capng_update"); | |
124 | return -1; | |
125 | } | |
126 | } | |
127 | return 0; | |
128 | } | |
129 | ||
130 | static int socket_read(int sockfd, void *buff, ssize_t size) | |
131 | { | |
132 | ssize_t retval, total = 0; | |
133 | ||
134 | while (size) { | |
135 | retval = read(sockfd, buff, size); | |
136 | if (retval == 0) { | |
137 | return -EIO; | |
138 | } | |
139 | if (retval < 0) { | |
140 | if (errno == EINTR) { | |
141 | continue; | |
142 | } | |
143 | return -errno; | |
144 | } | |
145 | size -= retval; | |
146 | buff += retval; | |
147 | total += retval; | |
148 | } | |
149 | return total; | |
150 | } | |
151 | ||
152 | static int socket_write(int sockfd, void *buff, ssize_t size) | |
153 | { | |
154 | ssize_t retval, total = 0; | |
155 | ||
156 | while (size) { | |
157 | retval = write(sockfd, buff, size); | |
158 | if (retval < 0) { | |
159 | if (errno == EINTR) { | |
160 | continue; | |
161 | } | |
162 | return -errno; | |
163 | } | |
164 | size -= retval; | |
165 | buff += retval; | |
166 | total += retval; | |
167 | } | |
168 | return total; | |
169 | } | |
170 | ||
171 | static int read_request(int sockfd, struct iovec *iovec, ProxyHeader *header) | |
172 | { | |
173 | int retval; | |
174 | ||
175 | /* | |
176 | * read the request header. | |
177 | */ | |
178 | iovec->iov_len = 0; | |
179 | retval = socket_read(sockfd, iovec->iov_base, PROXY_HDR_SZ); | |
180 | if (retval < 0) { | |
181 | return retval; | |
182 | } | |
183 | iovec->iov_len = PROXY_HDR_SZ; | |
184 | retval = proxy_unmarshal(iovec, 0, "dd", &header->type, &header->size); | |
185 | if (retval < 0) { | |
186 | return retval; | |
187 | } | |
188 | /* | |
189 | * We can't process message.size > PROXY_MAX_IO_SZ. | |
190 | * Treat it as fatal error | |
191 | */ | |
192 | if (header->size > PROXY_MAX_IO_SZ) { | |
193 | return -ENOBUFS; | |
194 | } | |
195 | retval = socket_read(sockfd, iovec->iov_base + PROXY_HDR_SZ, header->size); | |
196 | if (retval < 0) { | |
197 | return retval; | |
198 | } | |
199 | iovec->iov_len += header->size; | |
200 | return 0; | |
201 | } | |
202 | ||
203 | static int send_fd(int sockfd, int fd) | |
204 | { | |
205 | struct msghdr msg; | |
206 | struct iovec iov; | |
207 | int retval, data; | |
208 | struct cmsghdr *cmsg; | |
209 | union MsgControl msg_control; | |
210 | ||
211 | iov.iov_base = &data; | |
212 | iov.iov_len = sizeof(data); | |
213 | ||
214 | memset(&msg, 0, sizeof(msg)); | |
215 | msg.msg_iov = &iov; | |
216 | msg.msg_iovlen = 1; | |
217 | /* No ancillary data on error */ | |
218 | if (fd < 0) { | |
219 | /* fd is really negative errno if the request failed */ | |
220 | data = fd; | |
221 | } else { | |
222 | data = V9FS_FD_VALID; | |
223 | msg.msg_control = &msg_control; | |
224 | msg.msg_controllen = sizeof(msg_control); | |
225 | ||
226 | cmsg = &msg_control.cmsg; | |
227 | cmsg->cmsg_len = CMSG_LEN(sizeof(fd)); | |
228 | cmsg->cmsg_level = SOL_SOCKET; | |
229 | cmsg->cmsg_type = SCM_RIGHTS; | |
230 | memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd)); | |
231 | } | |
232 | ||
233 | do { | |
234 | retval = sendmsg(sockfd, &msg, 0); | |
235 | } while (retval < 0 && errno == EINTR); | |
236 | if (fd >= 0) { | |
237 | close(fd); | |
238 | } | |
239 | if (retval < 0) { | |
240 | return retval; | |
241 | } | |
242 | return 0; | |
243 | } | |
244 | ||
245 | static int send_status(int sockfd, struct iovec *iovec, int status) | |
246 | { | |
247 | ProxyHeader header; | |
248 | int retval, msg_size; | |
249 | ||
250 | if (status < 0) { | |
251 | header.type = T_ERROR; | |
252 | } else { | |
253 | header.type = T_SUCCESS; | |
254 | } | |
255 | header.size = sizeof(status); | |
256 | /* | |
257 | * marshal the return status. We don't check error. | |
258 | * because we are sure we have enough space for the status | |
259 | */ | |
260 | msg_size = proxy_marshal(iovec, 0, "ddd", header.type, | |
261 | header.size, status); | |
262 | if (msg_size < 0) { | |
263 | return msg_size; | |
264 | } | |
265 | retval = socket_write(sockfd, iovec->iov_base, msg_size); | |
266 | if (retval < 0) { | |
267 | return retval; | |
268 | } | |
269 | return 0; | |
270 | } | |
271 | ||
272 | /* | |
273 | * from man 7 capabilities, section | |
274 | * Effect of User ID Changes on Capabilities: | |
275 | * If the effective user ID is changed from nonzero to 0, then the permitted | |
276 | * set is copied to the effective set. If the effective user ID is changed | |
277 | * from 0 to nonzero, then all capabilities are are cleared from the effective | |
278 | * set. | |
279 | * | |
280 | * The setfsuid/setfsgid man pages warn that changing the effective user ID may | |
281 | * expose the program to unwanted signals, but this is not true anymore: for an | |
282 | * unprivileged (without CAP_KILL) program to send a signal, the real or | |
283 | * effective user ID of the sending process must equal the real or saved user | |
284 | * ID of the target process. Even when dropping privileges, it is enough to | |
285 | * keep the saved UID to a "privileged" value and virtfs-proxy-helper won't | |
286 | * be exposed to signals. So just use setresuid/setresgid. | |
287 | */ | |
288 | static int setugid(int uid, int gid, int *suid, int *sgid) | |
289 | { | |
290 | int retval; | |
291 | ||
292 | *suid = geteuid(); | |
293 | *sgid = getegid(); | |
294 | ||
295 | if (setresgid(-1, gid, *sgid) == -1) { | |
296 | return -errno; | |
297 | } | |
298 | ||
299 | if (setresuid(-1, uid, *suid) == -1) { | |
300 | retval = -errno; | |
301 | goto err_sgid; | |
302 | } | |
303 | ||
304 | if (uid == 0 && gid == 0) { | |
305 | /* Linux has already copied the permitted set to the effective set. */ | |
306 | return 0; | |
307 | } | |
308 | ||
309 | /* | |
310 | * All capabilities have been cleared from the effective set. However | |
311 | * we still need DAC_OVERRIDE because we don't change supplementary | |
312 | * group ids, and hence may be subject to DAC rules. init_capabilities | |
313 | * left the set of capabilities that we want in libcap-ng's state. | |
314 | */ | |
315 | if (capng_apply(CAPNG_SELECT_CAPS) < 0) { | |
316 | retval = -errno; | |
317 | do_perror("capng_apply"); | |
318 | goto err_suid; | |
319 | } | |
320 | return 0; | |
321 | ||
322 | err_suid: | |
323 | if (setresuid(-1, *suid, *suid) == -1) { | |
324 | abort(); | |
325 | } | |
326 | err_sgid: | |
327 | if (setresgid(-1, *sgid, *sgid) == -1) { | |
328 | abort(); | |
329 | } | |
330 | return retval; | |
331 | } | |
332 | ||
333 | /* | |
334 | * This is used to reset the ugid back with the saved values | |
335 | * There is nothing much we can do checking error values here. | |
336 | */ | |
337 | static void resetugid(int suid, int sgid) | |
338 | { | |
339 | if (setresgid(-1, sgid, sgid) == -1) { | |
340 | abort(); | |
341 | } | |
342 | if (setresuid(-1, suid, suid) == -1) { | |
343 | abort(); | |
344 | } | |
345 | } | |
346 | ||
347 | /* | |
348 | * Open regular file or directory. Attempts to open any special file are | |
349 | * rejected. | |
350 | * | |
351 | * returns file descriptor or -1 on error | |
352 | */ | |
353 | static int open_regular(const char *pathname, int flags, mode_t mode) | |
354 | { | |
355 | int fd; | |
356 | ||
357 | fd = open(pathname, flags, mode); | |
358 | if (fd < 0) { | |
359 | return fd; | |
360 | } | |
361 | ||
362 | if (close_if_special_file(fd) < 0) { | |
363 | return -1; | |
364 | } | |
365 | ||
366 | return fd; | |
367 | } | |
368 | ||
369 | /* | |
370 | * send response in two parts | |
371 | * 1) ProxyHeader | |
372 | * 2) Response or error status | |
373 | * This function should be called with marshaled response | |
374 | * send_response constructs header part and error part only. | |
375 | * send response sends {ProxyHeader,Response} if the request was success | |
376 | * otherwise sends {ProxyHeader,error status} | |
377 | */ | |
378 | static int send_response(int sock, struct iovec *iovec, int size) | |
379 | { | |
380 | int retval; | |
381 | ProxyHeader header; | |
382 | ||
383 | /* | |
384 | * If response size exceeds available iovec->iov_len, | |
385 | * we return ENOBUFS | |
386 | */ | |
387 | if (size > PROXY_MAX_IO_SZ) { | |
388 | size = -ENOBUFS; | |
389 | } | |
390 | ||
391 | if (size < 0) { | |
392 | /* | |
393 | * In case of error we would not have got the error encoded | |
394 | * already so encode the error here. | |
395 | */ | |
396 | header.type = T_ERROR; | |
397 | header.size = sizeof(size); | |
398 | proxy_marshal(iovec, PROXY_HDR_SZ, "d", size); | |
399 | } else { | |
400 | header.type = T_SUCCESS; | |
401 | header.size = size; | |
402 | } | |
403 | proxy_marshal(iovec, 0, "dd", header.type, header.size); | |
404 | retval = socket_write(sock, iovec->iov_base, header.size + PROXY_HDR_SZ); | |
405 | if (retval < 0) { | |
406 | return retval; | |
407 | } | |
408 | return 0; | |
409 | } | |
410 | ||
411 | /* | |
412 | * gets generation number | |
413 | * returns -errno on failure and sizeof(generation number) on success | |
414 | */ | |
415 | static int do_getversion(struct iovec *iovec, struct iovec *out_iovec) | |
416 | { | |
417 | uint64_t version; | |
418 | int retval = -ENOTTY; | |
419 | #ifdef FS_IOC_GETVERSION | |
420 | int fd; | |
421 | V9fsString path; | |
422 | #endif | |
423 | ||
424 | ||
425 | /* no need to issue ioctl */ | |
426 | if (!get_version) { | |
427 | version = 0; | |
428 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version); | |
429 | return retval; | |
430 | } | |
431 | #ifdef FS_IOC_GETVERSION | |
432 | retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path); | |
433 | if (retval < 0) { | |
434 | return retval; | |
435 | } | |
436 | ||
437 | fd = open(path.data, O_RDONLY); | |
438 | if (fd < 0) { | |
439 | retval = -errno; | |
440 | goto err_out; | |
441 | } | |
442 | if (ioctl(fd, FS_IOC_GETVERSION, &version) < 0) { | |
443 | retval = -errno; | |
444 | } else { | |
445 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version); | |
446 | } | |
447 | close(fd); | |
448 | err_out: | |
449 | v9fs_string_free(&path); | |
450 | #endif | |
451 | return retval; | |
452 | } | |
453 | ||
454 | static int do_getxattr(int type, struct iovec *iovec, struct iovec *out_iovec) | |
455 | { | |
456 | int size = 0, offset, retval; | |
457 | V9fsString path, name, xattr; | |
458 | ||
459 | v9fs_string_init(&xattr); | |
460 | v9fs_string_init(&path); | |
461 | retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "ds", &size, &path); | |
462 | if (retval < 0) { | |
463 | return retval; | |
464 | } | |
465 | offset = PROXY_HDR_SZ + retval; | |
466 | ||
467 | if (size) { | |
468 | xattr.data = g_malloc(size); | |
469 | xattr.size = size; | |
470 | } | |
471 | switch (type) { | |
472 | case T_LGETXATTR: | |
473 | v9fs_string_init(&name); | |
474 | retval = proxy_unmarshal(iovec, offset, "s", &name); | |
475 | if (retval > 0) { | |
476 | retval = lgetxattr(path.data, name.data, xattr.data, size); | |
477 | if (retval < 0) { | |
478 | retval = -errno; | |
479 | } else { | |
480 | xattr.size = retval; | |
481 | } | |
482 | } | |
483 | v9fs_string_free(&name); | |
484 | break; | |
485 | case T_LLISTXATTR: | |
486 | retval = llistxattr(path.data, xattr.data, size); | |
487 | if (retval < 0) { | |
488 | retval = -errno; | |
489 | } else { | |
490 | xattr.size = retval; | |
491 | } | |
492 | break; | |
493 | } | |
494 | if (retval < 0) { | |
495 | goto err_out; | |
496 | } | |
497 | ||
498 | if (!size) { | |
499 | proxy_marshal(out_iovec, PROXY_HDR_SZ, "d", retval); | |
500 | retval = sizeof(retval); | |
501 | } else { | |
502 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &xattr); | |
503 | } | |
504 | err_out: | |
505 | v9fs_string_free(&xattr); | |
506 | v9fs_string_free(&path); | |
507 | return retval; | |
508 | } | |
509 | ||
510 | static void stat_to_prstat(ProxyStat *pr_stat, struct stat *stat) | |
511 | { | |
512 | memset(pr_stat, 0, sizeof(*pr_stat)); | |
513 | pr_stat->st_dev = stat->st_dev; | |
514 | pr_stat->st_ino = stat->st_ino; | |
515 | pr_stat->st_nlink = stat->st_nlink; | |
516 | pr_stat->st_mode = stat->st_mode; | |
517 | pr_stat->st_uid = stat->st_uid; | |
518 | pr_stat->st_gid = stat->st_gid; | |
519 | pr_stat->st_rdev = stat->st_rdev; | |
520 | pr_stat->st_size = stat->st_size; | |
521 | pr_stat->st_blksize = stat->st_blksize; | |
522 | pr_stat->st_blocks = stat->st_blocks; | |
523 | pr_stat->st_atim_sec = stat->st_atim.tv_sec; | |
524 | pr_stat->st_atim_nsec = stat->st_atim.tv_nsec; | |
525 | pr_stat->st_mtim_sec = stat->st_mtim.tv_sec; | |
526 | pr_stat->st_mtim_nsec = stat->st_mtim.tv_nsec; | |
527 | pr_stat->st_ctim_sec = stat->st_ctim.tv_sec; | |
528 | pr_stat->st_ctim_nsec = stat->st_ctim.tv_nsec; | |
529 | } | |
530 | ||
531 | static void statfs_to_prstatfs(ProxyStatFS *pr_stfs, struct statfs *stfs) | |
532 | { | |
533 | memset(pr_stfs, 0, sizeof(*pr_stfs)); | |
534 | pr_stfs->f_type = stfs->f_type; | |
535 | pr_stfs->f_bsize = stfs->f_bsize; | |
536 | pr_stfs->f_blocks = stfs->f_blocks; | |
537 | pr_stfs->f_bfree = stfs->f_bfree; | |
538 | pr_stfs->f_bavail = stfs->f_bavail; | |
539 | pr_stfs->f_files = stfs->f_files; | |
540 | pr_stfs->f_ffree = stfs->f_ffree; | |
541 | pr_stfs->f_fsid[0] = stfs->f_fsid.__val[0]; | |
542 | pr_stfs->f_fsid[1] = stfs->f_fsid.__val[1]; | |
543 | pr_stfs->f_namelen = stfs->f_namelen; | |
544 | pr_stfs->f_frsize = stfs->f_frsize; | |
545 | } | |
546 | ||
547 | /* | |
548 | * Gets stat/statfs information and packs in out_iovec structure | |
549 | * on success returns number of bytes packed in out_iovec structure | |
550 | * otherwise returns -errno | |
551 | */ | |
552 | static int do_stat(int type, struct iovec *iovec, struct iovec *out_iovec) | |
553 | { | |
554 | int retval; | |
555 | V9fsString path; | |
556 | ProxyStat pr_stat; | |
557 | ProxyStatFS pr_stfs; | |
558 | struct stat st_buf; | |
559 | struct statfs stfs_buf; | |
560 | ||
561 | v9fs_string_init(&path); | |
562 | retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path); | |
563 | if (retval < 0) { | |
564 | return retval; | |
565 | } | |
566 | ||
567 | switch (type) { | |
568 | case T_LSTAT: | |
569 | retval = lstat(path.data, &st_buf); | |
570 | if (retval < 0) { | |
571 | retval = -errno; | |
572 | } else { | |
573 | stat_to_prstat(&pr_stat, &st_buf); | |
574 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, | |
575 | "qqqdddqqqqqqqqqq", pr_stat.st_dev, | |
576 | pr_stat.st_ino, pr_stat.st_nlink, | |
577 | pr_stat.st_mode, pr_stat.st_uid, | |
578 | pr_stat.st_gid, pr_stat.st_rdev, | |
579 | pr_stat.st_size, pr_stat.st_blksize, | |
580 | pr_stat.st_blocks, | |
581 | pr_stat.st_atim_sec, pr_stat.st_atim_nsec, | |
582 | pr_stat.st_mtim_sec, pr_stat.st_mtim_nsec, | |
583 | pr_stat.st_ctim_sec, pr_stat.st_ctim_nsec); | |
584 | } | |
585 | break; | |
586 | case T_STATFS: | |
587 | retval = statfs(path.data, &stfs_buf); | |
588 | if (retval < 0) { | |
589 | retval = -errno; | |
590 | } else { | |
591 | statfs_to_prstatfs(&pr_stfs, &stfs_buf); | |
592 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, | |
593 | "qqqqqqqqqqq", pr_stfs.f_type, | |
594 | pr_stfs.f_bsize, pr_stfs.f_blocks, | |
595 | pr_stfs.f_bfree, pr_stfs.f_bavail, | |
596 | pr_stfs.f_files, pr_stfs.f_ffree, | |
597 | pr_stfs.f_fsid[0], pr_stfs.f_fsid[1], | |
598 | pr_stfs.f_namelen, pr_stfs.f_frsize); | |
599 | } | |
600 | break; | |
601 | } | |
602 | v9fs_string_free(&path); | |
603 | return retval; | |
604 | } | |
605 | ||
606 | static int do_readlink(struct iovec *iovec, struct iovec *out_iovec) | |
607 | { | |
608 | char *buffer; | |
609 | int size, retval; | |
610 | V9fsString target, path; | |
611 | ||
612 | v9fs_string_init(&path); | |
613 | retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &size); | |
614 | if (retval < 0) { | |
615 | v9fs_string_free(&path); | |
616 | return retval; | |
617 | } | |
618 | buffer = g_malloc(size); | |
619 | v9fs_string_init(&target); | |
620 | retval = readlink(path.data, buffer, size - 1); | |
621 | if (retval > 0) { | |
622 | buffer[retval] = '\0'; | |
623 | v9fs_string_sprintf(&target, "%s", buffer); | |
624 | retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &target); | |
625 | } else { | |
626 | retval = -errno; | |
627 | } | |
628 | g_free(buffer); | |
629 | v9fs_string_free(&target); | |
630 | v9fs_string_free(&path); | |
631 | return retval; | |
632 | } | |
633 | ||
634 | /* | |
635 | * create other filesystem objects and send 0 on success | |
636 | * return -errno on error | |
637 | */ | |
638 | static int do_create_others(int type, struct iovec *iovec) | |
639 | { | |
640 | dev_t rdev; | |
641 | int retval = 0; | |
642 | int offset = PROXY_HDR_SZ; | |
643 | V9fsString oldpath, path; | |
644 | int mode, uid, gid, cur_uid, cur_gid; | |
645 | ||
646 | v9fs_string_init(&path); | |
647 | v9fs_string_init(&oldpath); | |
648 | ||
649 | retval = proxy_unmarshal(iovec, offset, "dd", &uid, &gid); | |
650 | if (retval < 0) { | |
651 | return retval; | |
652 | } | |
653 | offset += retval; | |
654 | retval = setugid(uid, gid, &cur_uid, &cur_gid); | |
655 | if (retval < 0) { | |
656 | goto unmarshal_err_out; | |
657 | } | |
658 | switch (type) { | |
659 | case T_MKNOD: | |
660 | retval = proxy_unmarshal(iovec, offset, "sdq", &path, &mode, &rdev); | |
661 | if (retval < 0) { | |
662 | goto err_out; | |
663 | } | |
664 | retval = mknod(path.data, mode, rdev); | |
665 | break; | |
666 | case T_MKDIR: | |
667 | retval = proxy_unmarshal(iovec, offset, "sd", &path, &mode); | |
668 | if (retval < 0) { | |
669 | goto err_out; | |
670 | } | |
671 | retval = g_mkdir(path.data, mode); | |
672 | break; | |
673 | case T_SYMLINK: | |
674 | retval = proxy_unmarshal(iovec, offset, "ss", &oldpath, &path); | |
675 | if (retval < 0) { | |
676 | goto err_out; | |
677 | } | |
678 | retval = symlink(oldpath.data, path.data); | |
679 | break; | |
680 | } | |
681 | if (retval < 0) { | |
682 | retval = -errno; | |
683 | } | |
684 | ||
685 | err_out: | |
686 | resetugid(cur_uid, cur_gid); | |
687 | unmarshal_err_out: | |
688 | v9fs_string_free(&path); | |
689 | v9fs_string_free(&oldpath); | |
690 | return retval; | |
691 | } | |
692 | ||
693 | /* | |
694 | * create a file and send fd on success | |
695 | * return -errno on error | |
696 | */ | |
697 | static int do_create(struct iovec *iovec) | |
698 | { | |
699 | int ret; | |
700 | V9fsString path; | |
701 | int flags, mode, uid, gid, cur_uid, cur_gid; | |
702 | ||
703 | v9fs_string_init(&path); | |
704 | ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sdddd", | |
705 | &path, &flags, &mode, &uid, &gid); | |
706 | if (ret < 0) { | |
707 | goto unmarshal_err_out; | |
708 | } | |
709 | ret = setugid(uid, gid, &cur_uid, &cur_gid); | |
710 | if (ret < 0) { | |
711 | goto unmarshal_err_out; | |
712 | } | |
713 | ret = open_regular(path.data, flags, mode); | |
714 | if (ret < 0) { | |
715 | ret = -errno; | |
716 | } | |
717 | ||
718 | resetugid(cur_uid, cur_gid); | |
719 | unmarshal_err_out: | |
720 | v9fs_string_free(&path); | |
721 | return ret; | |
722 | } | |
723 | ||
724 | /* | |
725 | * open a file and send fd on success | |
726 | * return -errno on error | |
727 | */ | |
728 | static int do_open(struct iovec *iovec) | |
729 | { | |
730 | int flags, ret; | |
731 | V9fsString path; | |
732 | ||
733 | v9fs_string_init(&path); | |
734 | ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &flags); | |
735 | if (ret < 0) { | |
736 | goto err_out; | |
737 | } | |
738 | ret = open_regular(path.data, flags, 0); | |
739 | if (ret < 0) { | |
740 | ret = -errno; | |
741 | } | |
742 | err_out: | |
743 | v9fs_string_free(&path); | |
744 | return ret; | |
745 | } | |
746 | ||
747 | /* create unix domain socket and return the descriptor */ | |
748 | static int proxy_socket(const char *path, uid_t uid, gid_t gid) | |
749 | { | |
750 | int sock, client; | |
751 | struct sockaddr_un proxy, qemu; | |
752 | socklen_t size; | |
753 | ||
754 | /* requested socket already exists, refuse to start */ | |
755 | if (!access(path, F_OK)) { | |
756 | do_log(LOG_CRIT, "socket already exists\n"); | |
757 | return -1; | |
758 | } | |
759 | ||
760 | if (strlen(path) >= sizeof(proxy.sun_path)) { | |
761 | do_log(LOG_CRIT, "UNIX domain socket path exceeds %zu characters\n", | |
762 | sizeof(proxy.sun_path)); | |
763 | return -1; | |
764 | } | |
765 | ||
766 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
767 | if (sock < 0) { | |
768 | do_perror("socket"); | |
769 | return -1; | |
770 | } | |
771 | ||
772 | /* mask other part of mode bits */ | |
773 | umask(7); | |
774 | ||
775 | proxy.sun_family = AF_UNIX; | |
776 | strcpy(proxy.sun_path, path); | |
777 | if (bind(sock, (struct sockaddr *)&proxy, | |
778 | sizeof(struct sockaddr_un)) < 0) { | |
779 | do_perror("bind"); | |
780 | goto error; | |
781 | } | |
782 | if (chown(proxy.sun_path, uid, gid) < 0) { | |
783 | do_perror("chown"); | |
784 | goto error; | |
785 | } | |
786 | if (listen(sock, 1) < 0) { | |
787 | do_perror("listen"); | |
788 | goto error; | |
789 | } | |
790 | ||
791 | size = sizeof(qemu); | |
792 | client = accept(sock, (struct sockaddr *)&qemu, &size); | |
793 | if (client < 0) { | |
794 | do_perror("accept"); | |
795 | goto error; | |
796 | } | |
797 | close(sock); | |
798 | return client; | |
799 | ||
800 | error: | |
801 | close(sock); | |
802 | return -1; | |
803 | } | |
804 | ||
805 | static void usage(void) | |
806 | { | |
807 | fprintf(stderr, "usage: %s\n" | |
808 | " -p|--path <path> 9p path to export\n" | |
809 | " {-f|--fd <socket-descriptor>} socket file descriptor to be used\n" | |
810 | " {-s|--socket <socketname> socket file used for communication\n" | |
811 | " \t-u|--uid <uid> -g|--gid <gid>} - uid:gid combination to give " | |
812 | " access to this socket\n" | |
813 | " \tNote: -s & -f can not be used together\n" | |
814 | " [-n|--nodaemon] Run as a normal program\n", | |
815 | prog_name); | |
816 | } | |
817 | ||
818 | static int process_reply(int sock, int type, | |
819 | struct iovec *out_iovec, int retval) | |
820 | { | |
821 | switch (type) { | |
822 | case T_OPEN: | |
823 | case T_CREATE: | |
824 | if (send_fd(sock, retval) < 0) { | |
825 | return -1; | |
826 | } | |
827 | break; | |
828 | case T_MKNOD: | |
829 | case T_MKDIR: | |
830 | case T_SYMLINK: | |
831 | case T_LINK: | |
832 | case T_CHMOD: | |
833 | case T_CHOWN: | |
834 | case T_TRUNCATE: | |
835 | case T_UTIME: | |
836 | case T_RENAME: | |
837 | case T_REMOVE: | |
838 | case T_LSETXATTR: | |
839 | case T_LREMOVEXATTR: | |
840 | if (send_status(sock, out_iovec, retval) < 0) { | |
841 | return -1; | |
842 | } | |
843 | break; | |
844 | case T_LSTAT: | |
845 | case T_STATFS: | |
846 | case T_READLINK: | |
847 | case T_LGETXATTR: | |
848 | case T_LLISTXATTR: | |
849 | case T_GETVERSION: | |
850 | if (send_response(sock, out_iovec, retval) < 0) { | |
851 | return -1; | |
852 | } | |
853 | break; | |
854 | default: | |
855 | return -1; | |
856 | break; | |
857 | } | |
858 | return 0; | |
859 | } | |
860 | ||
861 | static int process_requests(int sock) | |
862 | { | |
863 | int flags; | |
864 | int size = 0; | |
865 | int retval = 0; | |
866 | uint64_t offset; | |
867 | ProxyHeader header; | |
868 | int mode, uid, gid; | |
869 | V9fsString name, value; | |
870 | struct timespec spec[2]; | |
871 | V9fsString oldpath, path; | |
872 | struct iovec in_iovec, out_iovec; | |
873 | ||
874 | in_iovec.iov_base = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ); | |
875 | in_iovec.iov_len = PROXY_MAX_IO_SZ + PROXY_HDR_SZ; | |
876 | out_iovec.iov_base = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ); | |
877 | out_iovec.iov_len = PROXY_MAX_IO_SZ + PROXY_HDR_SZ; | |
878 | ||
879 | while (1) { | |
880 | /* | |
881 | * initialize the header type, so that we send | |
882 | * response to proper request type. | |
883 | */ | |
884 | header.type = 0; | |
885 | retval = read_request(sock, &in_iovec, &header); | |
886 | if (retval < 0) { | |
887 | goto err_out; | |
888 | } | |
889 | ||
890 | switch (header.type) { | |
891 | case T_OPEN: | |
892 | retval = do_open(&in_iovec); | |
893 | break; | |
894 | case T_CREATE: | |
895 | retval = do_create(&in_iovec); | |
896 | break; | |
897 | case T_MKNOD: | |
898 | case T_MKDIR: | |
899 | case T_SYMLINK: | |
900 | retval = do_create_others(header.type, &in_iovec); | |
901 | break; | |
902 | case T_LINK: | |
903 | v9fs_string_init(&path); | |
904 | v9fs_string_init(&oldpath); | |
905 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, | |
906 | "ss", &oldpath, &path); | |
907 | if (retval > 0) { | |
908 | retval = link(oldpath.data, path.data); | |
909 | if (retval < 0) { | |
910 | retval = -errno; | |
911 | } | |
912 | } | |
913 | v9fs_string_free(&oldpath); | |
914 | v9fs_string_free(&path); | |
915 | break; | |
916 | case T_LSTAT: | |
917 | case T_STATFS: | |
918 | retval = do_stat(header.type, &in_iovec, &out_iovec); | |
919 | break; | |
920 | case T_READLINK: | |
921 | retval = do_readlink(&in_iovec, &out_iovec); | |
922 | break; | |
923 | case T_CHMOD: | |
924 | v9fs_string_init(&path); | |
925 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, | |
926 | "sd", &path, &mode); | |
927 | if (retval > 0) { | |
928 | retval = chmod(path.data, mode); | |
929 | if (retval < 0) { | |
930 | retval = -errno; | |
931 | } | |
932 | } | |
933 | v9fs_string_free(&path); | |
934 | break; | |
935 | case T_CHOWN: | |
936 | v9fs_string_init(&path); | |
937 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sdd", &path, | |
938 | &uid, &gid); | |
939 | if (retval > 0) { | |
940 | retval = lchown(path.data, uid, gid); | |
941 | if (retval < 0) { | |
942 | retval = -errno; | |
943 | } | |
944 | } | |
945 | v9fs_string_free(&path); | |
946 | break; | |
947 | case T_TRUNCATE: | |
948 | v9fs_string_init(&path); | |
949 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sq", | |
950 | &path, &offset); | |
951 | if (retval > 0) { | |
952 | retval = truncate(path.data, offset); | |
953 | if (retval < 0) { | |
954 | retval = -errno; | |
955 | } | |
956 | } | |
957 | v9fs_string_free(&path); | |
958 | break; | |
959 | case T_UTIME: | |
960 | v9fs_string_init(&path); | |
961 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sqqqq", &path, | |
962 | &spec[0].tv_sec, &spec[0].tv_nsec, | |
963 | &spec[1].tv_sec, &spec[1].tv_nsec); | |
964 | if (retval > 0) { | |
965 | retval = utimensat(AT_FDCWD, path.data, spec, | |
966 | AT_SYMLINK_NOFOLLOW); | |
967 | if (retval < 0) { | |
968 | retval = -errno; | |
969 | } | |
970 | } | |
971 | v9fs_string_free(&path); | |
972 | break; | |
973 | case T_RENAME: | |
974 | v9fs_string_init(&path); | |
975 | v9fs_string_init(&oldpath); | |
976 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, | |
977 | "ss", &oldpath, &path); | |
978 | if (retval > 0) { | |
979 | retval = rename(oldpath.data, path.data); | |
980 | if (retval < 0) { | |
981 | retval = -errno; | |
982 | } | |
983 | } | |
984 | v9fs_string_free(&oldpath); | |
985 | v9fs_string_free(&path); | |
986 | break; | |
987 | case T_REMOVE: | |
988 | v9fs_string_init(&path); | |
989 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "s", &path); | |
990 | if (retval > 0) { | |
991 | retval = remove(path.data); | |
992 | if (retval < 0) { | |
993 | retval = -errno; | |
994 | } | |
995 | } | |
996 | v9fs_string_free(&path); | |
997 | break; | |
998 | case T_LGETXATTR: | |
999 | case T_LLISTXATTR: | |
1000 | retval = do_getxattr(header.type, &in_iovec, &out_iovec); | |
1001 | break; | |
1002 | case T_LSETXATTR: | |
1003 | v9fs_string_init(&path); | |
1004 | v9fs_string_init(&name); | |
1005 | v9fs_string_init(&value); | |
1006 | retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sssdd", &path, | |
1007 | &name, &value, &size, &flags); | |
1008 | if (retval > 0) { | |
1009 | retval = lsetxattr(path.data, | |
1010 | name.data, value.data, size, flags); | |
1011 | if (retval < 0) { | |
1012 | retval = -errno; | |
1013 | } | |
1014 | } | |
1015 | v9fs_string_free(&path); | |
1016 | v9fs_string_free(&name); | |
1017 | v9fs_string_free(&value); | |
1018 | break; | |
1019 | case T_LREMOVEXATTR: | |
1020 | v9fs_string_init(&path); | |
1021 | v9fs_string_init(&name); | |
1022 | retval = proxy_unmarshal(&in_iovec, | |
1023 | PROXY_HDR_SZ, "ss", &path, &name); | |
1024 | if (retval > 0) { | |
1025 | retval = lremovexattr(path.data, name.data); | |
1026 | if (retval < 0) { | |
1027 | retval = -errno; | |
1028 | } | |
1029 | } | |
1030 | v9fs_string_free(&path); | |
1031 | v9fs_string_free(&name); | |
1032 | break; | |
1033 | case T_GETVERSION: | |
1034 | retval = do_getversion(&in_iovec, &out_iovec); | |
1035 | break; | |
1036 | default: | |
1037 | goto err_out; | |
1038 | break; | |
1039 | } | |
1040 | ||
1041 | if (process_reply(sock, header.type, &out_iovec, retval) < 0) { | |
1042 | goto err_out; | |
1043 | } | |
1044 | } | |
1045 | err_out: | |
1046 | g_free(in_iovec.iov_base); | |
1047 | g_free(out_iovec.iov_base); | |
1048 | return -1; | |
1049 | } | |
1050 | ||
1051 | int main(int argc, char **argv) | |
1052 | { | |
1053 | int sock; | |
1054 | uid_t own_u; | |
1055 | gid_t own_g; | |
1056 | char *rpath = NULL; | |
1057 | char *sock_name = NULL; | |
1058 | struct stat stbuf; | |
1059 | int c, option_index; | |
1060 | #ifdef FS_IOC_GETVERSION | |
1061 | int retval; | |
1062 | struct statfs st_fs; | |
1063 | #endif | |
1064 | ||
1065 | fprintf(stderr, "NOTE: The 9p 'proxy' backend is deprecated (since " | |
1066 | "QEMU 8.1) and will be removed in a future version of " | |
1067 | "QEMU!\n"); | |
1068 | ||
1069 | prog_name = g_path_get_basename(argv[0]); | |
1070 | ||
1071 | is_daemon = true; | |
1072 | sock = -1; | |
1073 | own_u = own_g = -1; | |
1074 | while (1) { | |
1075 | option_index = 0; | |
1076 | c = getopt_long(argc, argv, "p:nh?f:s:u:g:", helper_opts, | |
1077 | &option_index); | |
1078 | if (c == -1) { | |
1079 | break; | |
1080 | } | |
1081 | switch (c) { | |
1082 | case 'p': | |
1083 | rpath = g_strdup(optarg); | |
1084 | break; | |
1085 | case 'n': | |
1086 | is_daemon = false; | |
1087 | break; | |
1088 | case 'f': | |
1089 | sock = atoi(optarg); | |
1090 | break; | |
1091 | case 's': | |
1092 | sock_name = g_strdup(optarg); | |
1093 | break; | |
1094 | case 'u': | |
1095 | own_u = atoi(optarg); | |
1096 | break; | |
1097 | case 'g': | |
1098 | own_g = atoi(optarg); | |
1099 | break; | |
1100 | case '?': | |
1101 | case 'h': | |
1102 | default: | |
1103 | usage(); | |
1104 | exit(EXIT_FAILURE); | |
1105 | } | |
1106 | } | |
1107 | ||
1108 | /* Parameter validation */ | |
1109 | if ((sock_name == NULL && sock == -1) || rpath == NULL) { | |
1110 | fprintf(stderr, "socket, socket descriptor or path not specified\n"); | |
1111 | usage(); | |
1112 | return -1; | |
1113 | } | |
1114 | ||
1115 | if (sock_name && sock != -1) { | |
1116 | fprintf(stderr, "both named socket and socket descriptor specified\n"); | |
1117 | usage(); | |
1118 | exit(EXIT_FAILURE); | |
1119 | } | |
1120 | ||
1121 | if (sock_name && (own_u == -1 || own_g == -1)) { | |
1122 | fprintf(stderr, "owner uid:gid not specified, "); | |
1123 | fprintf(stderr, | |
1124 | "owner uid:gid specifies who can access the socket file\n"); | |
1125 | usage(); | |
1126 | exit(EXIT_FAILURE); | |
1127 | } | |
1128 | ||
1129 | if (lstat(rpath, &stbuf) < 0) { | |
1130 | fprintf(stderr, "invalid path \"%s\" specified, %s\n", | |
1131 | rpath, strerror(errno)); | |
1132 | exit(EXIT_FAILURE); | |
1133 | } | |
1134 | ||
1135 | if (!S_ISDIR(stbuf.st_mode)) { | |
1136 | fprintf(stderr, "specified path \"%s\" is not directory\n", rpath); | |
1137 | exit(EXIT_FAILURE); | |
1138 | } | |
1139 | ||
1140 | if (is_daemon) { | |
1141 | if (daemon(0, 0) < 0) { | |
1142 | fprintf(stderr, "daemon call failed\n"); | |
1143 | exit(EXIT_FAILURE); | |
1144 | } | |
1145 | openlog(PROGNAME, LOG_PID, LOG_DAEMON); | |
1146 | } | |
1147 | ||
1148 | do_log(LOG_INFO, "Started\n"); | |
1149 | if (sock_name) { | |
1150 | sock = proxy_socket(sock_name, own_u, own_g); | |
1151 | if (sock < 0) { | |
1152 | goto error; | |
1153 | } | |
1154 | } | |
1155 | ||
1156 | if (chroot(rpath) < 0) { | |
1157 | do_perror("chroot"); | |
1158 | goto error; | |
1159 | } | |
1160 | if (chdir("/") < 0) { | |
1161 | do_perror("chdir"); | |
1162 | goto error; | |
1163 | } | |
1164 | ||
1165 | get_version = false; | |
1166 | #ifdef FS_IOC_GETVERSION | |
1167 | /* check whether underlying FS support IOC_GETVERSION */ | |
1168 | retval = statfs("/", &st_fs); | |
1169 | if (!retval) { | |
1170 | switch (st_fs.f_type) { | |
1171 | case EXT2_SUPER_MAGIC: | |
1172 | case BTRFS_SUPER_MAGIC: | |
1173 | case REISERFS_SUPER_MAGIC: | |
1174 | case XFS_SUPER_MAGIC: | |
1175 | get_version = true; | |
1176 | break; | |
1177 | } | |
1178 | } | |
1179 | #endif | |
1180 | ||
1181 | umask(0); | |
1182 | if (init_capabilities() < 0) { | |
1183 | goto error; | |
1184 | } | |
1185 | ||
1186 | process_requests(sock); | |
1187 | error: | |
1188 | g_free(rpath); | |
1189 | g_free(sock_name); | |
1190 | do_log(LOG_INFO, "Done\n"); | |
1191 | closelog(); | |
1192 | return 0; | |
1193 | } |