scip/udpxd
1
0
Fork 0
mirror of https://codeberg.org/scip/udpxd.git synced 2025-12-16 11:30:57 +01:00
Code Issues Packages Projects Releases Wiki Activity

changed -d to -t; -d is now for daemonizing, removed -f; drop privileges if run as root and in daemon mode and chroot

Browse Source
This commit is contained in:
git@daemon.de
2015-04-27 14:04:57 +02:00
parent b34aab38b6
commit e8d40a7dc5
8 changed files with 198 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
.travis.yml
View File

@@ -10,8 +10,8 @@ compiler:
script:
- make
- sudo make install
- sudo udpxd -l 127.0.0.1:53 -d 8.8.8.8:53
- sudo udpxd -l [::1]:53 -d [2001:4860:4860::8888]:53
- sudo udpxd -l 127.0.0.1:53 -d 8.8.8.8:53 -d
- sudo udpxd -l [::1]:53 -t [2001:4860:4860::8888]:53 -d
- dig +nocmd +noall +answer google.de a @127.0.0.1
- dig +nocmd +noall +answer google.de a @::1
- sudo killall udpxd

4
appveyor.yml
View File

@@ -25,8 +25,8 @@ install:
build_script:
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; make"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; cygstart --hide ./udpxd -l 127.0.0.1:53 -d 8.8.8.8:53 -f"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; cygstart --hide ./udpxd -l [::1]:53 -d 8.8.8.8:53 -f"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; cygstart --hide ./udpxd -l 127.0.0.1:53 -t 8.8.8.8:53"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; cygstart --hide ./udpxd -l [::1]:53 -t 8.8.8.8:53"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; dig www.google.de soa @127.0.0.1"'
- '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; dig www.google.de soa @::1"'

102
net.c
View File

@@ -81,9 +81,14 @@ int bindsocket( host_t *sock_h) {
return fd;
}
int start_listener (char *inip, char *inpt, char *srcip, char *dstip, char *dstpt, char *pidfile) {
host_t *listen_h, *dst_h, *bind_h;
/*
returns:
-1: error in any case
0: parent not forked (fork disabled)
1: parent after successful fork
2: child after successful fork
*/
int daemonize(char *pidfile) {
if(FORKED) {
// fork
pid_t pid, sid;
@@ -100,15 +105,16 @@ int start_listener (char *inip, char *inpt, char *srcip, char *dstip, char *dstp
/* leave parent */
if((fd = fopen(pidfile, "w")) == NULL) {
perror("failed to write pidfile");
return 1;
return -1;
}
else {
fprintf(fd, "%d\n", pid);
fclose(fd);
}
return 0;
return 1;
}
/* child */
sid = setsid();
if (sid < 0) {
@@ -116,17 +122,82 @@ int start_listener (char *inip, char *inpt, char *srcip, char *dstip, char *dstp
return 1;
}
umask(0);
openlog("udpxd", LOG_NOWAIT|LOG_PID, LOG_USER);
return 2;
}
return 0;
}
int drop_privileges(char *user, char *chrootdir) {
struct passwd *pw = getpwnam(user);
uid_t me = getuid();
if ((chdir("/")) < 0) {
perror("failed to chdir to /");
return 1;
}
umask(0);
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
if(me == 0) {
/* drop privileges */
if(chroot(chrootdir) != 0) {
perror("failed to chroot");
return 1;
}
openlog("udpxd", LOG_NOWAIT|LOG_PID, LOG_USER);
if(pw == NULL) {
perror("user not found");
return 1;
}
if(setegid(pw->pw_gid) != 0) {
perror("could not set egid");
return 1;
}
if(setgid(pw->pw_gid) != 0) {
perror("could not set gid");
return 1;
}
if(setuid(pw->pw_uid) != 0) {
perror("could not set uid");
return 1;
}
if(seteuid(pw->pw_uid) != 0) {
perror("could not set euid");
return 1;
}
if (setuid(0) != -1) {
fprintf(stderr, "error, managed to regain root privileges after dropping them!\n");
return 1;
}
}
return 0;
}
int start_listener (char *inip, char *inpt, char *srcip, char *dstip,
char *dstpt, char *pidfile, char *chrootdir, char *user) {
host_t *listen_h, *dst_h, *bind_h;
int dm = daemonize(pidfile);
switch(dm) {
case -1:
return 1; /* parent, fork error */
break;
case 0:
break; /* parent, not forking */
case 1:
return 0; /* parent, fork ok, leave */
break;
case 2:
break; /* child, fork ok, continue */
}
listen_h = get_host(inip, atoi(inpt), NULL, NULL);
@@ -157,6 +228,17 @@ int start_listener (char *inip, char *inpt, char *srcip, char *dstip, char *dstp
verbose("\n");
}
if(drop_privileges(user, chrootdir) != 0) {
host_clean(bind_h);
host_clean(listen_h);
host_clean(dst_h);
return 1;
}
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
main_loop(listen, listen_h, bind_h, dst_h);
host_clean(bind_h);

6
net.h
View File

@@ -38,6 +38,7 @@
#include <sys/types.h>
#include <sys/fcntl.h>
#include <arpa/inet.h>
#include <pwd.h>
#include "client.h"
@@ -54,7 +55,10 @@ void handle_inside(int inside, host_t *listen_h, host_t *bind_h, host_t *dst_h);
void handle_outside(int inside, int outside, host_t *outside_h);
int main_loop(int listensocket, host_t *listen_h, host_t *bind_h, host_t *dst_h);
int start_listener (char *inip, char *inpt, char *srcip, char *dstip, char *dstpt, char *pidfile);
int start_listener (char *inip, char *inpt, char *srcip, char *dstip,
char *dstpt, char *pidfile, char *chrootdir, char *user);
int daemonize(char *pidfile);
int drop_privileges(char *user, char *chrootdir);
int fill_set(fd_set *fds);
int get_sender(fd_set *fds);

43
udpxd.1
View File

@@ -124,7 +124,7 @@
.\" ========================================================================
.\"
.IX Title "UDPXD 1"
.TH UDPXD 1 "2015-04-26" "perl v5.14.2" "User Contributed Perl Documentation"
.TH UDPXD 1 "2015-04-27" "perl v5.14.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
@@ -139,12 +139,14 @@ udpxd \- A general purpose UDP relay/port forwarder/proxy
\& Options:
\& \-\-listen \-l <ip:port> listen for incoming requests
\& \-\-bind \-b <ip> bind ip used for outgoing requests
\& \-\-dest \-d <ip:port> destination to forward requests to
\& \-\-foreground \-f don\*(Aqt fork into background
\& \-\-to \-t <ip:port> destination to forward requests to
\& \-\-daemon \-d daemon mode, fork into background
\& \-\-pidfile \-p <file> pidfile, default: /var/run/udpxd.pid
\& \-\-user \-u <user> run as user (only in daemon mode)
\& \-\-chroot \-c <path> chroot to <path> (only in daemon mode)
\& \-\-help \-h \-? print help message
\& \-\-version \-v print program version
\& \-\-verbose \-V enable verbose logging
\& \-\-version \-V print program version
\& \-\-verbose \-v enable verbose logging
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
@@ -155,7 +157,7 @@ for outgoing packets.
.PP
It listens on the ip address and port specified with \fB\-l\fR
and waits for incoming udp packets. If one arrives, it sends
it to the destination specified with \fB\-d\fR. Responses will
it to the destination specified with \fB\-t\fR. Responses will
be sent back accordingly.
.PP
If \fB\-b\fR has not been specified, udpxd uses the operating
@@ -165,23 +167,25 @@ binds to the given ip address and uses this as the source
address.
.PP
In any case, udpxd behaves like a proxy. The receiving end
(\fB\-d\fR) only sees the source ip address of the outgoing
(\fB\-t\fR) only sees the source ip address of the outgoing
interface of the system running udpxd or the address specified
with \fB\-b\fR.
.PP
The options \fB\-l\fR and \fB\-d\fR are mandatory.
The options \fB\-l\fR and \fB\-t\fR are mandatory.
.PP
If the option \fB\-f\fR has not been specified, udpxd forks into
If the option \fB\-d\fR has been specified, udpxd forks into
the background and becomes a daemon. It writes it pidfile to
\&\f(CW\*(C`/var/run/udpxd.pid\*(C'\fR, which can be changed with the \fB\-p\fR
option.
option. If started as root, it also drops privileges to the
user \f(CW\*(C`nobody\*(C'\fR or the user specified with \fB\-u\fR and chroots
to \f(CW\*(C`/var/empty\*(C'\fR or the directory specified with \fB\-c\fR.
.PP
\&\fBCaution: udpxd does not drop its privileges. If started as
root, it will continue to run as root. This may change in the
future.\fR
\&\fBCaution: if not running in daemon mode, udpxd does not drop
its privileges and will continue to run as root (if started as
root).\fR
.PP
Udpxd supports ip version 4 and 6, it doesn't support hostnames,
\&\-l, \-d and \-b must be ip addresses. In order to specify an ipv6
\&\fB\-l\fR, \fB\-t\fR and \fB\-b\fR must be ip addresses. In order to specify an ipv6
address and a port, use:
.PP
.Vb 1
@@ -216,7 +220,7 @@ an ntp server in network 192.168.1.0/24; and you dont operate a
firewall, nat or routing on 'foo'. Run udpxd like this:
.PP
.Vb 1
\& udpxd \-l 10.0.0.1:123 \-d 192.168.1.199:123
\& udpxd \-l 10.0.0.1:123 \-t 192.168.1.199:123
.Ve
.PP
Now, if a client with the source ip address 10.0.0.110 sends
@@ -244,7 +248,7 @@ In order to use 192.168.1.45 as the source ip address, use the
\&\fB\-b\fR parameter:
.PP
.Vb 1
\& udpxd \-l 10.0.0.1:123 \-d 192.168.1.199:123 \-b 192.168.1.45
\& udpxd \-l 10.0.0.1:123 \-t 192.168.1.199:123 \-b 192.168.1.45
.Ve
.PP
In this case for the client everything looks as before, but the
@@ -255,19 +259,18 @@ Here we listen on the ip v6 loopback address and forward traffic
to another ip v6 destination address:
.PP
.Vb 1
\& udpxd \-l [::1]:53 \-d [2001:4860:4860::8888]:53
\& udpxd \-l [::1]:53 \-t [2001:4860:4860::8888]:53
.Ve
.PP
Or, we could listen on an ip v4 address and forward to an ip v6
address:
.PP
.Vb 1
\& udpxd \-l 192.168.1.1:53 \-d [2001:4860:4860::8888]:53
\& udpxd \-l 192.168.1.1:53 \-t [2001:4860:4860::8888]:53
.Ve
.SH "FILES"
.IX Header "FILES"
\&\fB/var/run/udpxd.pid\fR: created if running in daemon mode (\-f not
specified).
\&\fB/var/run/udpxd.pid\fR: created if running in daemon mode (\fB\-d\fR).
.SH "BUGS"
.IX Header "BUGS"
In order to report a bug, unexpected behavior, feature requests

79
udpxd.c
View File

@@ -26,7 +26,7 @@
/* global client list */
client_t *clients = NULL;
int VERBOSE = 0;
int FORKED = 1;
int FORKED = 0;
/* parse ip:port */
int parse_ip(char *src, char *ip, char *pt) {
@@ -87,23 +87,47 @@ int parse_ip(char *src, char *ip, char *pt) {
void usage() {
fprintf(stderr,
"Usage: udpxd [-lbdfpvhV]\n\n"
"Options:\n"
"--listen -l <ip:port> listen for incoming requests\n"
"--bind -b <ip> bind ip used for outgoing requests\n"
"--to -t <ip:port> destination to forward requests to\n"
"--daemon -d daemon mode, fork into background\n"
"--pidfile -p <file> pidfile, default: /var/run/udpxd.pid\n"
"--user -u <user> run as user (only in daemon mode)\n"
"--chroot -c <path> chroot to <path> (only in daemon mode)\n"
"--help -h -? print help message\n"
"--version -V print program version\n"
"--verbose -v enable verbose logging\n\n"
"Options -l and -t are mandatory.\n\n"
"This is udpxd version %s.\n", UDPXD_VERSION
);
}
int main ( int argc, char* argv[] ) {
int opt, err;
char *inip, *inpt, *srcip, *dstip, *dstpt;
char pidfile[MAX_BUFFER_SIZE];
char user[128];
char chroot[MAX_BUFFER_SIZE];
err = 0;
static struct option longopts[] = {
{ "listen", required_argument, NULL, 'l' },
{ "bind", required_argument, NULL, 'b' },
{ "dest", required_argument, NULL, 'd' },
{ "version", no_argument, NULL, 'v' },
{ "to", required_argument, NULL, 't' },
{ "version", no_argument, NULL, 'V' },
{ "help", no_argument, NULL, 'h' },
{ "verbose", no_argument, NULL, 'V' },
{ "foreground",no_argument, NULL, 'f' },
{ "verbose", no_argument, NULL, 'v' },
{ "daemon", no_argument, NULL, 'd' },
{ "pidfile", required_argument, NULL, 'p' },
{ "user", required_argument, NULL, 'u' },
{ "chroot", required_argument, NULL, 'c' },
};
if( argc < 2 ) {
@@ -112,23 +136,27 @@ int main ( int argc, char* argv[] ) {
}
srcip = dstip = inip = dstpt = inpt = NULL;
strncpy(pidfile, "/var/run/udpxd.pid", 19);
while ((opt = getopt_long(argc, argv, "l:b:d:vfVh?", longopts, NULL)) != -1) {
/* set defaults */
strncpy(pidfile, "/var/run/udpxd.pid", 19);
strncpy(user, "nobody", 7);
strncpy(chroot, "/var/empty", 11);
while ((opt = getopt_long(argc, argv, "l:b:t:u:c:vdVh?", longopts, NULL)) != -1) {
switch (opt) {
case 'v':
case 'V':
fprintf(stderr, "This is %s version %s\n", argv[0], UDPXD_VERSION);
return 1;
break;
case 'f':
FORKED = 0;
case 'd':
FORKED = 1;
break;
case 'h':
case '?':
usage();
return 1;
break;
case 'V':
case 'v':
VERBOSE = 1;
break;
case 'l':
@@ -139,7 +167,7 @@ int main ( int argc, char* argv[] ) {
err = 1;
}
break;
case 'd':
case 't':
dstip = malloc(INET6_ADDRSTRLEN+1);
dstpt = malloc(6);
if (parse_ip(optarg, dstip, dstpt) != 0) {
@@ -158,6 +186,12 @@ int main ( int argc, char* argv[] ) {
case 'p':
strncpy(pidfile, optarg, strlen(optarg));
break;
case 'u':
strncpy(user, optarg, strlen(optarg));
break;
case 'c':
strncpy(chroot, optarg, strlen(optarg));
break;
default:
usage();
return 1;
@@ -172,7 +206,7 @@ int main ( int argc, char* argv[] ) {
}
if(dstip == NULL) {
fprintf(stderr, "-d parameter is required!\n");
fprintf(stderr, "-t parameter is required!\n");
usage();
err = 1;
}
@@ -185,7 +219,7 @@ int main ( int argc, char* argv[] ) {
}
if(! err) {
err = start_listener (inip, inpt, srcip, dstip, dstpt, pidfile);
err = start_listener (inip, inpt, srcip, dstip, dstpt, pidfile, chroot, user);
}
if(srcip != NULL)
@@ -201,20 +235,3 @@ int main ( int argc, char* argv[] ) {
return err;
}
void usage() {
fprintf(stderr,
"Usage: udpxd [-lbdfpvhV]\n\n"
"Options:\n"
"--listen -l <ip:port> listen for incoming requests\n"
"--bind -b <ip> bind ip used for outgoing requests\n"
"--dest -d <ip:port> destination to forward requests to\n"
"--foreground -f don't fork into background\n"
"--pidfile -p <file> pidfile, default: /var/run/udpxd.pid\n"
"--help -h -? print help message\n"
"--version -v print program version\n"
"--verbose -V enable verbose logging\n\n"
"Options -l and -d are mandatory.\n\n"
"This is udpxd version %s.\n", UDPXD_VERSION
);
}

2
udpxd.h
View File

@@ -36,7 +36,7 @@
#include <sys/fcntl.h>
#include <arpa/inet.h>
#define UDPXD_VERSION "0.0.2"
#define UDPXD_VERSION "0.0.3"
void usage();

43
udpxd.pod
View File

@@ -9,12 +9,14 @@ udpxd - A general purpose UDP relay/port forwarder/proxy
Options:
--listen -l <ip:port> listen for incoming requests
--bind -b <ip> bind ip used for outgoing requests
--dest -d <ip:port> destination to forward requests to
--foreground -f don't fork into background
--to -t <ip:port> destination to forward requests to
--daemon -d daemon mode, fork into background
--pidfile -p <file> pidfile, default: /var/run/udpxd.pid
--user -u <user> run as user (only in daemon mode)
--chroot -c <path> chroot to <path> (only in daemon mode)
--help -h -? print help message
--version -v print program version
--verbose -V enable verbose logging
--version -V print program version
--verbose -v enable verbose logging
=head1 DESCRIPTION
@@ -25,7 +27,7 @@ for outgoing packets.
It listens on the ip address and port specified with B<-l>
and waits for incoming udp packets. If one arrives, it sends
it to the destination specified with B<-d>. Responses will
it to the destination specified with B<-t>. Responses will
be sent back accordingly.
If B<-b> has not been specified, udpxd uses the operating
@@ -35,23 +37,27 @@ binds to the given ip address and uses this as the source
address.
In any case, udpxd behaves like a proxy. The receiving end
(B<-d>) only sees the source ip address of the outgoing
(B<-t>) only sees the source ip address of the outgoing
interface of the system running udpxd or the address specified
with B<-b>.
The options B<-l> and B<-d> are mandatory.
The options B<-l> and B<-t> are mandatory.
If the option B<-f> has not been specified, udpxd forks into
If the option B<-d> has been specified, udpxd forks into
the background and becomes a daemon. It writes it pidfile to
C</var/run/udpxd.pid>, which can be changed with the B<-p>
option.
option. If started as root, it also drops privileges to the
user C<nobody> or the user specified with B<-u> and chroots
to C</var/empty> or the directory specified with B<-c>. udpxd
will log to syslog facility user.info if B<-v> is specified and
if running in daemon mode.
B<Caution: udpxd does not drop its privileges. If started as
root, it will continue to run as root. This may change in the
future.>
B<Caution: if not running in daemon mode, udpxd does not drop
its privileges and will continue to run as root (if started as
root).>
Udpxd supports ip version 4 and 6, it doesn't support hostnames,
-l, -d and -b must be ip addresses. In order to specify an ipv6
B<-l>, B<-t> and B<-b> must be ip addresses. In order to specify an ipv6
address and a port, use:
-l [::1]:53
@@ -80,7 +86,7 @@ And let's say, you have a client in network 10.0.0.0/24 who whiches to reach
an ntp server in network 192.168.1.0/24; and you dont operate a
firewall, nat or routing on 'foo'. Run udpxd like this:
udpxd -l 10.0.0.1:123 -d 192.168.1.199:123
udpxd -l 10.0.0.1:123 -t 192.168.1.199:123
Now, if a client with the source ip address 10.0.0.110 sends
a ntp request to 10.0.0.1:123, udpxd will forward that
@@ -104,7 +110,7 @@ of the interface for outgoing packets.
In order to use 192.168.1.45 as the source ip address, use the
B<-b> parameter:
udpxd -l 10.0.0.1:123 -d 192.168.1.199:123 -b 192.168.1.45
udpxd -l 10.0.0.1:123 -t 192.168.1.199:123 -b 192.168.1.45
In this case for the client everything looks as before, but the
ntp server on the other end will see ntp requests coming from
@@ -113,17 +119,16 @@ ntp server on the other end will see ntp requests coming from
Here we listen on the ip v6 loopback address and forward traffic
to another ip v6 destination address:
udpxd -l [::1]:53 -d [2001:4860:4860::8888]:53
udpxd -l [::1]:53 -t [2001:4860:4860::8888]:53
Or, we could listen on an ip v4 address and forward to an ip v6
address:
udpxd -l 192.168.1.1:53 -d [2001:4860:4860::8888]:53
udpxd -l 192.168.1.1:53 -t [2001:4860:4860::8888]:53
=head1 FILES
B</var/run/udpxd.pid>: created if running in daemon mode (-f not
specified).
B</var/run/udpxd.pid>: created if running in daemon mode (B<-d>).
=head1 BUGS