2 * Copyright (c) 2014, 2016 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "socket-util.h"
22 #include <sys/ioctl.h>
23 #include <sys/types.h>
28 #include "fatal-signal.h"
31 #include "openvswitch/vlog.h"
33 VLOG_DEFINE_THIS_MODULE(socket_util_unix
);
35 /* #ifdefs make it a pain to maintain code: you have to try to build both ways.
36 * Thus, this file compiles all of the code regardless of the target, by
37 * writing "if (LINUX)" instead of "#ifdef __linux__". */
48 /* Maximum length of the sun_path member in a struct sockaddr_un, excluding
49 * space for a null terminator. */
50 #define MAX_UN_LEN (sizeof(((struct sockaddr_un *) 0)->sun_path) - 1)
56 VLOG_FATAL("failed to create pipe (%s)", ovs_strerror(errno
));
61 xpipe_nonblocking(int fds
[2])
64 xset_nonblocking(fds
[0]);
65 xset_nonblocking(fds
[1]);
68 /* Drain all the data currently in the receive queue of a datagram socket (and
69 * possibly additional data). There is no way to know how many packets are in
70 * the receive queue, but we do know that the total number of bytes queued does
71 * not exceed the receive buffer size, so we pull packets until none are left
72 * or we've read that many bytes. */
78 rcvbuf
= get_socket_rcvbuf(fd
);
84 /* In Linux, specifying MSG_TRUNC in the flags argument causes the
85 * datagram length to be returned, even if that is longer than the
86 * buffer provided. Thus, we can use a 1-byte buffer to discard the
87 * incoming datagram and still be able to account how many bytes were
88 * removed from the receive buffer.
90 * On other Unix-like OSes, MSG_TRUNC has no effect in the flags
92 char buffer
[LINUX
? 1 : 2048];
93 ssize_t n_bytes
= recv(fd
, buffer
, sizeof buffer
,
94 MSG_TRUNC
| MSG_DONTWAIT
);
95 if (n_bytes
<= 0 || n_bytes
>= rcvbuf
) {
103 /* Attempts to shorten 'name' by opening a file descriptor for the directory
104 * part of the name and indirecting through /proc/self/fd/<dirfd>/<basename>.
105 * On systems with Linux-like /proc, this works as long as <basename> isn't too
108 * On success, returns 0 and stores the short name in 'short_name' and a
109 * directory file descriptor to eventually be closed in '*dirfpd'. */
111 shorten_name_via_proc(const char *name
, char short_name
[MAX_UN_LEN
+ 1],
122 dir
= dir_name(name
);
123 dirfd
= open(dir
, O_DIRECTORY
| O_RDONLY
);
125 static struct vlog_rate_limit rl
= VLOG_RATE_LIMIT_INIT(1, 1);
128 VLOG_WARN_RL(&rl
, "%s: open failed (%s)", dir
, ovs_strerror(error
));
135 base
= base_name(name
);
136 len
= snprintf(short_name
, MAX_UN_LEN
+ 1,
137 "/proc/self/fd/%d/%s", dirfd
, base
);
140 if (len
>= 0 && len
<= MAX_UN_LEN
) {
149 /* Attempts to shorten 'name' by creating a symlink for the directory part of
150 * the name and indirecting through <symlink>/<basename>. This works on
151 * systems that support symlinks, as long as <basename> isn't too long.
153 * On success, returns 0 and stores the short name in 'short_name' and the
154 * symbolic link to eventually delete in 'linkname'. */
156 shorten_name_via_symlink(const char *name
, char short_name
[MAX_UN_LEN
+ 1],
157 char linkname
[MAX_UN_LEN
+ 1])
159 char *abs
, *dir
, *base
;
164 abs
= abs_file_name(NULL
, name
);
166 base
= base_name(abs
);
169 tmpdir
= getenv("TMPDIR");
170 if (tmpdir
== NULL
) {
174 for (i
= 0; i
< 1000; i
++) {
177 len
= snprintf(linkname
, MAX_UN_LEN
+ 1,
178 "%s/ovs-un-c-%"PRIu32
, tmpdir
, random_uint32());
179 error
= (len
< 0 || len
> MAX_UN_LEN
? ENAMETOOLONG
180 : symlink(dir
, linkname
) ? errno
182 if (error
!= EEXIST
) {
190 fatal_signal_add_file_to_unlink(linkname
);
192 len
= snprintf(short_name
, MAX_UN_LEN
+ 1, "%s/%s", linkname
, base
);
193 if (len
< 0 || len
> MAX_UN_LEN
) {
194 fatal_signal_unlink_file_now(linkname
);
195 error
= ENAMETOOLONG
;
208 /* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in
209 * '*un_len' the size of the sockaddr_un.
211 * Returns 0 on success, otherwise a positive errno value.
213 * Uses '*dirfdp' and 'linkname' to store references to data when the caller no
214 * longer needs to use 'un'. On success, freeing these references with
215 * free_sockaddr_un() is mandatory to avoid a leak; on failure, freeing them is
216 * unnecessary but harmless. */
218 make_sockaddr_un(const char *name
, struct sockaddr_un
*un
, socklen_t
*un_len
,
219 int *dirfdp
, char linkname
[MAX_UN_LEN
+ 1])
221 char short_name
[MAX_UN_LEN
+ 1];
225 if (strlen(name
) > MAX_UN_LEN
) {
226 /* 'name' is too long to fit in a sockaddr_un. Try a workaround. */
227 int error
= shorten_name_via_proc(name
, short_name
, dirfdp
);
228 if (error
== ENAMETOOLONG
) {
229 error
= shorten_name_via_symlink(name
, short_name
, linkname
);
232 static struct vlog_rate_limit rl
= VLOG_RATE_LIMIT_INIT(1, 1);
234 VLOG_WARN_RL(&rl
, "Unix socket name %s is longer than maximum "
235 "%"PRIuSIZE
" bytes", name
, MAX_UN_LEN
);
242 un
->sun_family
= AF_UNIX
;
243 ovs_strzcpy(un
->sun_path
, name
, sizeof un
->sun_path
);
244 *un_len
= (offsetof(struct sockaddr_un
, sun_path
)
245 + strlen (un
->sun_path
) + 1);
249 /* Clean up after make_sockaddr_un(). */
251 free_sockaddr_un(int dirfd
, const char *linkname
)
257 fatal_signal_unlink_file_now(linkname
);
261 /* Binds Unix domain socket 'fd' to a file with permissions 0700. */
262 static int bind_unix_socket(int fd
, struct sockaddr
*sun
, socklen_t sun_len
)
264 const mode_t mode
= 0770; /* Allow both user and group access. */
267 /* On Linux, the fd's permissions become the file's permissions.
268 * fchmod() does not affect other files, like umask() does. */
269 if (fchmod(fd
, mode
)) {
273 /* Must be after fchmod(). */
274 if (bind(fd
, sun
, sun_len
)) {
279 /* On FreeBSD and NetBSD, only the umask affects permissions. The
280 * umask is process-wide rather than thread-specific, so we have to use
281 * a subprocess for safety. */
286 _exit(bind(fd
, sun
, sun_len
) ? errno
: 0);
287 } else if (pid
> 0) {
292 error
= waitpid(pid
, &status
, 0) < 0 ? errno
: 0;
293 } while (error
== EINTR
);
295 return (error
? error
296 : WIFEXITED(status
) ? WEXITSTATUS(status
)
297 : WIFSIGNALED(status
) ? EINTR
298 : ECHILD
/* WTF? */);
305 /* Creates a Unix domain socket in the given 'style' (either SOCK_DGRAM or
306 * SOCK_STREAM) that is bound to '*bind_path' (if 'bind_path' is non-null) and
307 * connected to '*connect_path' (if 'connect_path' is non-null). If 'nonblock'
308 * is true, the socket is made non-blocking.
310 * Returns the socket's fd if successful, otherwise a negative errno value. */
312 make_unix_socket(int style
, bool nonblock
,
313 const char *bind_path
, const char *connect_path
)
318 fd
= socket(PF_UNIX
, style
, 0);
323 /* Set nonblocking mode right away, if we want it. This prevents blocking
324 * in connect(), if connect_path != NULL. (In turn, that's a corner case:
325 * it will only happen if style is SOCK_STREAM or SOCK_SEQPACKET, and only
326 * if a backlog of un-accepted connections has built up in the kernel.) */
328 error
= set_nonblocking(fd
);
335 char linkname
[MAX_UN_LEN
+ 1];
336 struct sockaddr_un un
;
340 if (unlink(bind_path
) && errno
!= ENOENT
) {
341 VLOG_WARN("unlinking \"%s\": %s\n",
342 bind_path
, ovs_strerror(errno
));
344 fatal_signal_add_file_to_unlink(bind_path
);
346 error
= make_sockaddr_un(bind_path
, &un
, &un_len
, &dirfd
, linkname
);
348 error
= bind_unix_socket(fd
, (struct sockaddr
*) &un
, un_len
);
350 free_sockaddr_un(dirfd
, linkname
);
358 char linkname
[MAX_UN_LEN
+ 1];
359 struct sockaddr_un un
;
363 error
= make_sockaddr_un(connect_path
, &un
, &un_len
, &dirfd
, linkname
);
365 && connect(fd
, (struct sockaddr
*) &un
, un_len
)
366 && errno
!= EINPROGRESS
) {
369 free_sockaddr_un(dirfd
, linkname
);
379 if (error
== EAGAIN
) {
383 fatal_signal_unlink_file_now(bind_path
);
390 get_unix_name_len(const struct sockaddr_un
*sun
, socklen_t sun_len
)
392 return (sun_len
> offsetof(struct sockaddr_un
, sun_path
) &&
393 sun
->sun_path
[0] != 0
394 ? sun_len
- offsetof(struct sockaddr_un
, sun_path
)
398 /* Calls ioctl() on an AF_INET sock, passing the specified 'command' and
399 * 'arg'. Returns 0 if successful, otherwise a positive errno value. */
401 af_inet_ioctl(unsigned long int command
, const void *arg
)
403 static struct ovsthread_once once
= OVSTHREAD_ONCE_INITIALIZER
;
406 if (ovsthread_once_start(&once
)) {
407 sock
= socket(AF_INET
, SOCK_DGRAM
, 0);
409 int error
= sock_errno();
410 VLOG_ERR("failed to create inet socket: %s", sock_strerror(error
));
413 ovsthread_once_done(&once
);
416 return (sock
< 0 ? -sock
417 : ioctl(sock
, command
, arg
) == -1 ? errno
422 af_inet_ifreq_ioctl(const char *name
, struct ifreq
*ifr
, unsigned long int cmd
,
423 const char *cmd_name
)
427 ovs_strzcpy(ifr
->ifr_name
, name
, sizeof ifr
->ifr_name
);
428 error
= af_inet_ioctl(cmd
, ifr
);
430 static struct vlog_rate_limit rl
= VLOG_RATE_LIMIT_INIT(5, 20);
431 VLOG_DBG_RL(&rl
, "%s: ioctl(%s) failed: %s", name
, cmd_name
,
432 ovs_strerror(error
));