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socket-util: Work around Unix domain socket path name limits on Linux.

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Many Open vSwitch tests fail on Debian's automatic build machines because
the builds occur in deeply nested directories with long names.  OVS tries
to bind and connect to Unix domain sockets using absolute path names, which
in combination with long directory names means that the socket's name
exceeds the limit for Unix domain socket names (108 bytes on Linux).

This commit works around the problem on Linux by indirecting through
/proc/self/fd/<dirfd>/<basename> when names exceed the maximum that can be
used directly.

Reported-by: Hector Oron <hector.oron@gmail.com>
Reported-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reported-by: Roger Leigh <rleigh@codelibre.net>
Debian bug #602891.
Debian bug #602911.
This commit is contained in:
Ben Pfaff
2010-11-09 15:58:36 -08:00
parent e61c056cb9
commit 6e170b4c78
6 changed files with 199 additions and 9 deletions
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107
lib/socket-util.c
View File

@@ -45,6 +45,10 @@ VLOG_DEFINE_THIS_MODULE(socket_util);
#define LINUX 0
#endif
#ifndef O_DIRECTORY
#define O_DIRECTORY 0
#endif
/* Sets 'fd' to non-blocking mode. Returns 0 if successful, otherwise a
* positive errno value. */
int
@@ -212,7 +216,7 @@ drain_fd(int fd, size_t n_packets)
/* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in
* '*un_len' the size of the sockaddr_un. */
static void
make_sockaddr_un(const char *name, struct sockaddr_un* un, socklen_t *un_len)
make_sockaddr_un__(const char *name, struct sockaddr_un *un, socklen_t *un_len)
{
un->sun_family = AF_UNIX;
strncpy(un->sun_path, name, sizeof un->sun_path);
@@ -221,6 +225,68 @@ make_sockaddr_un(const char *name, struct sockaddr_un* un, socklen_t *un_len)
+ strlen (un->sun_path) + 1);
}
/* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in
* '*un_len' the size of the sockaddr_un.
*
* Returns 0 on success, otherwise a positive errno value. On success,
* '*dirfdp' is either -1 or a nonnegative file descriptor that the caller
* should close after using '*un' to bind or connect. On failure, '*dirfdp' is
* -1. */
static int
make_sockaddr_un(const char *name, struct sockaddr_un *un, socklen_t *un_len,
int *dirfdp)
{
enum { MAX_UN_LEN = sizeof un->sun_path - 1 };
*dirfdp = -1;
if (strlen(name) > MAX_UN_LEN) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
if (LINUX) {
/* 'name' is too long to fit in a sockaddr_un, but we have a
* workaround for that on Linux: shorten it by opening a file
* descriptor for the directory part of the name and indirecting
* through /proc/self/fd/<dirfd>/<basename>. */
char *dir, *base;
char *short_name;
int dirfd;
dir = dir_name(name);
base = base_name(name);
dirfd = open(dir, O_DIRECTORY | O_RDONLY);
if (dirfd < 0) {
return errno;
}
short_name = xasprintf("/proc/self/fd/%d/%s", dirfd, base);
free(dir);
free(base);
if (strlen(short_name) <= MAX_UN_LEN) {
make_sockaddr_un__(short_name, un, un_len);
free(short_name);
*dirfdp = dirfd;
return 0;
}
free(short_name);
close(dirfd);
VLOG_WARN_RL(&rl, "Unix socket name %s is longer than maximum "
"%d bytes (even shortened)", name, MAX_UN_LEN);
} else {
/* 'name' is too long and we have no workaround. */
VLOG_WARN_RL(&rl, "Unix socket name %s is longer than maximum "
"%d bytes", name, MAX_UN_LEN);
}
return ENAMETOOLONG;
} else {
make_sockaddr_un__(name, un, un_len);
return 0;
}
}
/* Creates a Unix domain socket in the given 'style' (either SOCK_DGRAM or
* SOCK_STREAM) that is bound to '*bind_path' (if 'bind_path' is non-null) and
* connected to '*connect_path' (if 'connect_path' is non-null). If 'nonblock'
@@ -247,9 +313,11 @@ make_unix_socket(int style, bool nonblock, bool passcred OVS_UNUSED,
if (nonblock) {
int flags = fcntl(fd, F_GETFL, 0);
if (flags == -1) {
error = errno;
goto error;
}
if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
error = errno;
goto error;
}
}
@@ -257,13 +325,22 @@ make_unix_socket(int style, bool nonblock, bool passcred OVS_UNUSED,
if (bind_path) {
struct sockaddr_un un;
socklen_t un_len;
make_sockaddr_un(bind_path, &un, &un_len);
if (unlink(un.sun_path) && errno != ENOENT) {
VLOG_WARN("unlinking \"%s\": %s\n", un.sun_path, strerror(errno));
int dirfd;
if (unlink(bind_path) && errno != ENOENT) {
VLOG_WARN("unlinking \"%s\": %s\n", bind_path, strerror(errno));
}
fatal_signal_add_file_to_unlink(bind_path);
if (bind(fd, (struct sockaddr*) &un, un_len)
|| fchmod(fd, S_IRWXU)) {
error = make_sockaddr_un(bind_path, &un, &un_len, &dirfd);
if (!error && (bind(fd, (struct sockaddr*) &un, un_len)
|| fchmod(fd, S_IRWXU))) {
error = errno;
}
if (dirfd >= 0) {
close(dirfd);
}
if (error) {
goto error;
}
}
@@ -271,9 +348,18 @@ make_unix_socket(int style, bool nonblock, bool passcred OVS_UNUSED,
if (connect_path) {
struct sockaddr_un un;
socklen_t un_len;
make_sockaddr_un(connect_path, &un, &un_len);
if (connect(fd, (struct sockaddr*) &un, un_len)
int dirfd;
error = make_sockaddr_un(connect_path, &un, &un_len, &dirfd);
if (!error
&& connect(fd, (struct sockaddr*) &un, un_len)
&& errno != EINPROGRESS) {
error = errno;
}
if (dirfd >= 0) {
close(dirfd);
}
if (error) {
goto error;
}
}
@@ -282,6 +368,7 @@ make_unix_socket(int style, bool nonblock, bool passcred OVS_UNUSED,
if (passcred) {
int enable = 1;
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &enable, sizeof(enable))) {
error = errno;
goto error;
}
}
@@ -290,7 +377,9 @@ make_unix_socket(int style, bool nonblock, bool passcred OVS_UNUSED,
return fd;
error:
error = errno == EAGAIN ? EPROTO : errno;
if (error == EAGAIN) {
error = EPROTO;
}
if (bind_path) {
fatal_signal_remove_file_to_unlink(bind_path);
}