|
|
- From 709646d59d96cb73a7e70347f37de9823e4e5f14 Mon Sep 17 00:00:00 2001
- From: Leonid Evdokimov <leon@darkk.net.ru>
- Date: Fri, 13 Apr 2012 01:57:23 +0400
- Subject: [PATCH 03/12] Initial support for UDP + TPROXY redirection. No more
- dest_ip in redudp.
-
- * TPROXY requires Linux 2.6.29+ (see man 7 ip[1]).
- * all redsocks code is running as root to bind to arbitrary port.
- * Non-Linux and old-Linux builds are broken at the moment.
-
- [1] http://www.kernel.org/doc/man-pages/online/pages/man7/ip.7.html
- ---
- dnstc.c | 2 +-
- redudp.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
- redudp.h | 2 +
- utils.c | 43 +++++++++++++-
- utils.h | 2 +-
- 5 files changed, 227 insertions(+), 19 deletions(-)
-
- diff --git a/dnstc.c b/dnstc.c
- index 43881d8..5f9fedd 100644
- --- a/dnstc.c
- +++ b/dnstc.c
- @@ -68,7 +68,7 @@ static void dnstc_pkt_from_client(int fd, short what, void *_arg)
- ssize_t pktlen, outgoing;
-
- assert(fd == EVENT_FD(&self->listener));
- - pktlen = red_recv_udp_pkt(fd, buf.raw, sizeof(buf), &clientaddr);
- + pktlen = red_recv_udp_pkt(fd, buf.raw, sizeof(buf), &clientaddr, NULL);
- if (pktlen == -1)
- return;
-
- diff --git a/redudp.c b/redudp.c
- index 9516a50..262af3e 100644
- --- a/redudp.c
- +++ b/redudp.c
- @@ -15,6 +15,7 @@
- */
-
- #include <stdlib.h>
- +#include <search.h>
- #include <string.h>
- #include <sys/types.h>
- #include <sys/uio.h>
- @@ -33,30 +34,157 @@
- #include "redudp.h"
-
- #define redudp_log_error(client, prio, msg...) \
- - redsocks_log_write_plain(__FILE__, __LINE__, __func__, 0, &(client)->clientaddr, &(client)->instance->config.destaddr, prio, ## msg)
- + redsocks_log_write_plain(__FILE__, __LINE__, __func__, 0, &(client)->clientaddr, get_destaddr(client), prio, ## msg)
- #define redudp_log_errno(client, prio, msg...) \
- - redsocks_log_write_plain(__FILE__, __LINE__, __func__, 1, &(client)->clientaddr, &(client)->instance->config.destaddr, prio, ## msg)
- + redsocks_log_write_plain(__FILE__, __LINE__, __func__, 1, &(client)->clientaddr, get_destaddr(client), prio, ## msg)
-
- static void redudp_pkt_from_socks(int fd, short what, void *_arg);
- static void redudp_drop_client(redudp_client *client);
- static void redudp_fini_instance(redudp_instance *instance);
- static int redudp_fini();
- +static int redudp_transparent(int fd);
-
- typedef struct redudp_expected_assoc_reply_t {
- socks5_reply h;
- socks5_addr_ipv4 ip;
- } PACKED redudp_expected_assoc_reply;
-
- +struct bound_udp4_key {
- + struct in_addr sin_addr;
- + uint16_t sin_port;
- +};
- +
- +struct bound_udp4 {
- + struct bound_udp4_key key;
- + int ref;
- + int fd;
- +};
- +
- /***********************************************************************
- * Helpers
- */
- +// TODO: separate binding to privileged process (this operation requires uid-0)
- +static void* root_bound_udp4 = NULL; // to avoid two binds to same IP:port
- +
- +static int bound_udp4_cmp(const void *a, const void *b)
- +{
- + return memcmp(a, b, sizeof(struct bound_udp4_key));
- +}
- +
- +static void bound_udp4_mkkey(struct bound_udp4_key *key, const struct sockaddr_in *addr)
- +{
- + memset(key, 0, sizeof(*key));
- + key->sin_addr = addr->sin_addr;
- + key->sin_port = addr->sin_port;
- +}
- +
- +static int bound_udp4_get(const struct sockaddr_in *addr)
- +{
- + struct bound_udp4_key key;
- + struct bound_udp4 *node, **pnode;
- +
- + bound_udp4_mkkey(&key, addr);
- + // I assume, that memory allocation for lookup is awful, so I use
- + // tfind/tsearch pair instead of tsearch/check-result.
- + pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
- + if (pnode) {
- + assert((*pnode)->ref > 0);
- + (*pnode)->ref++;
- + return (*pnode)->fd;
- + }
- +
- + node = calloc(1, sizeof(*node));
- + if (!node) {
- + log_errno(LOG_ERR, "calloc");
- + goto fail;
- + }
- +
- + node->key = key;
- + node->ref = 1;
- + node->fd = socket(AF_INET, SOCK_DGRAM, 0);
- + if (node->fd == -1) {
- + log_errno(LOG_ERR, "socket");
- + goto fail;
- + }
- +
- + if (0 != redudp_transparent(node->fd))
- + goto fail;
- +
- + if (0 != bind(node->fd, (struct sockaddr*)addr, sizeof(*addr))) {
- + log_errno(LOG_ERR, "bind");
- + goto fail;
- + }
- +
- + pnode = tsearch(node, &root_bound_udp4, bound_udp4_cmp);
- + if (!pnode) {
- + log_errno(LOG_ERR, "tsearch(%p) == %p", node, pnode);
- + goto fail;
- + }
- + assert(node == *pnode);
- +
- + return node->fd;
- +
- +fail:
- + if (node) {
- + if (node->fd != -1)
- + redsocks_close(node->fd);
- + free(node);
- + }
- + return -1;
- +}
- +
- +static void bound_udp4_put(const struct sockaddr_in *addr)
- +{
- + struct bound_udp4_key key;
- + struct bound_udp4 **pnode, *node;
- + void *parent;
- +
- + bound_udp4_mkkey(&key, addr);
- + pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
- + assert(pnode && (*pnode)->ref > 0);
- +
- + node = *pnode;
- +
- + node->ref--;
- + if (node->ref)
- + return;
- +
- + parent = tdelete(node, &root_bound_udp4, bound_udp4_cmp);
- + assert(parent);
- +
- + redsocks_close(node->fd); // expanding `pnode` to avoid use after free
- + free(node);
- +}
- +
- +static int redudp_transparent(int fd)
- +{
- + int on = 1;
- + int error = setsockopt(fd, SOL_IP, IP_TRANSPARENT, &on, sizeof(on));
- + if (error)
- + log_errno(LOG_ERR, "setsockopt(..., SOL_IP, IP_TRANSPARENT)");
- + return error;
- +}
- +
- +static int do_tproxy(redudp_instance* instance)
- +{
- + return instance->config.destaddr.sin_addr.s_addr == 0;
- +}
- +
- +static struct sockaddr_in* get_destaddr(redudp_client *client)
- +{
- + if (do_tproxy(client->instance))
- + return &client->destaddr;
- + else
- + return &client->instance->config.destaddr;
- +}
- +
- static void redudp_fill_preamble(socks5_udp_preabmle *preamble, redudp_client *client)
- {
- preamble->reserved = 0;
- preamble->frag_no = 0; /* fragmentation is not supported */
- preamble->addrtype = socks5_addrtype_ipv4;
- - preamble->ip.addr = client->instance->config.destaddr.sin_addr.s_addr;
- - preamble->ip.port = client->instance->config.destaddr.sin_port;
- + preamble->ip.addr = get_destaddr(client)->sin_addr.s_addr;
- + preamble->ip.port = get_destaddr(client)->sin_port;
- }
-
- static struct evbuffer* socks5_mkmethods_plain_wrapper(void *p)
- @@ -104,6 +232,8 @@ static void redudp_drop_client(redudp_client *client)
- redudp_log_errno(client, LOG_ERR, "event_del");
- redsocks_close(fd);
- }
- + if (client->sender_fd != -1)
- + bound_udp4_put(&client->destaddr);
- list_for_each_entry_safe(q, tmp, &client->queue, list) {
- list_del(&q->list);
- free(q);
- @@ -344,7 +474,8 @@ static void redudp_relay_connected(struct bufferevent *buffev, void *_arg)
- redudp_client *client = _arg;
- int do_password = socks5_is_valid_cred(client->instance->config.login, client->instance->config.password);
- int error;
- - redudp_log_error(client, LOG_DEBUG, "<trace>");
- + char relayaddr_str[RED_INET_ADDRSTRLEN];
- + redudp_log_error(client, LOG_DEBUG, "via %s", red_inet_ntop(&client->instance->config.relayaddr, relayaddr_str, sizeof(relayaddr_str)));
-
- if (!red_is_socket_connected_ok(buffev)) {
- redudp_log_errno(client, LOG_NOTICE, "red_is_socket_connected_ok");
- @@ -382,7 +513,7 @@ static void redudp_timeout(int fd, short what, void *_arg)
- redudp_drop_client(client);
- }
-
- -static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_in *clientaddr, char *buf, size_t pktlen)
- +static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_in *clientaddr, struct sockaddr_in *destaddr, char *buf, size_t pktlen)
- {
- redudp_client *client = calloc(1, sizeof(*client));
-
- @@ -395,9 +526,13 @@ static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_
- INIT_LIST_HEAD(&client->queue);
- client->instance = self;
- memcpy(&client->clientaddr, clientaddr, sizeof(*clientaddr));
- + if (destaddr)
- + memcpy(&client->destaddr, destaddr, sizeof(client->destaddr));
- evtimer_set(&client->timeout, redudp_timeout, client);
- // XXX: self->relay_ss->init(client);
-
- + client->sender_fd = -1; // it's postponed until socks-server replies to avoid trivial DoS
- +
- client->relay = red_connect_relay(&client->instance->config.relayaddr,
- redudp_relay_connected, redudp_relay_error, client);
- if (!client->relay)
- @@ -431,7 +566,7 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
-
- assert(fd == EVENT_FD(&client->udprelay));
-
- - pktlen = red_recv_udp_pkt(fd, pkt.buf, sizeof(pkt.buf), &udprelayaddr);
- + pktlen = red_recv_udp_pkt(fd, pkt.buf, sizeof(pkt.buf), &udprelayaddr, NULL);
- if (pktlen == -1)
- return;
-
- @@ -455,8 +590,8 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
- return;
- }
-
- - if (pkt.header.ip.port != client->instance->config.destaddr.sin_port ||
- - pkt.header.ip.addr != client->instance->config.destaddr.sin_addr.s_addr)
- + if (pkt.header.ip.port != get_destaddr(client)->sin_port ||
- + pkt.header.ip.addr != get_destaddr(client)->sin_addr.s_addr)
- {
- char buf[RED_INET_ADDRSTRLEN];
- struct sockaddr_in pktaddr = {
- @@ -472,8 +607,18 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
- redsocks_time(&client->last_relay_event);
- redudp_bump_timeout(client);
-
- + if (do_tproxy(client->instance) && client->sender_fd == -1) {
- + client->sender_fd = bound_udp4_get(&client->destaddr);
- + if (client->sender_fd == -1) {
- + redudp_log_error(client, LOG_WARNING, "bound_udp4_get failure");
- + return;
- + }
- + }
- +
- fwdlen = pktlen - sizeof(pkt.header);
- - outgoing = sendto(EVENT_FD(&client->instance->listener),
- + outgoing = sendto(do_tproxy(client->instance)
- + ? client->sender_fd
- + : EVENT_FD(&client->instance->listener),
- pkt.buf + sizeof(pkt.header), fwdlen, 0,
- (struct sockaddr*)&client->clientaddr, sizeof(client->clientaddr));
- if (outgoing != fwdlen) {
- @@ -486,18 +631,21 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
- static void redudp_pkt_from_client(int fd, short what, void *_arg)
- {
- redudp_instance *self = _arg;
- - struct sockaddr_in clientaddr;
- + struct sockaddr_in clientaddr, destaddr, *pdestaddr;
- char buf[0xFFFF]; // UDP packet can't be larger then that
- ssize_t pktlen;
- redudp_client *tmp, *client = NULL;
-
- + pdestaddr = do_tproxy(self) ? &destaddr : NULL;
- +
- assert(fd == EVENT_FD(&self->listener));
- - pktlen = red_recv_udp_pkt(fd, buf, sizeof(buf), &clientaddr);
- + pktlen = red_recv_udp_pkt(fd, buf, sizeof(buf), &clientaddr, pdestaddr);
- if (pktlen == -1)
- return;
-
- // TODO: this lookup may be SLOOOOOW.
- list_for_each_entry(tmp, &self->clients, list) {
- + // TODO: check destaddr
- if (0 == memcmp(&clientaddr, &tmp->clientaddr, sizeof(clientaddr))) {
- client = tmp;
- break;
- @@ -515,7 +663,7 @@ static void redudp_pkt_from_client(int fd, short what, void *_arg)
- }
- }
- else {
- - redudp_first_pkt_from_client(self, &clientaddr, buf, pktlen);
- + redudp_first_pkt_from_client(self, &clientaddr, pdestaddr, buf, pktlen);
- }
- }
-
- @@ -554,7 +702,6 @@ static int redudp_onenter(parser_section *section)
- instance->config.relayaddr.sin_family = AF_INET;
- instance->config.relayaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
- instance->config.destaddr.sin_family = AF_INET;
- - instance->config.destaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
- instance->config.max_pktqueue = 5;
- instance->config.udp_timeout = 30;
- instance->config.udp_timeout_stream = 180;
- @@ -614,6 +761,28 @@ static int redudp_init_instance(redudp_instance *instance)
- goto fail;
- }
-
- + if (do_tproxy(instance)) {
- + int on = 1;
- + char buf[RED_INET_ADDRSTRLEN];
- + // iptables TPROXY target does not send packets to non-transparent sockets
- + if (0 != redudp_transparent(fd))
- + goto fail;
- +
- + error = setsockopt(fd, SOL_IP, IP_RECVORIGDSTADDR, &on, sizeof(on));
- + if (error) {
- + log_errno(LOG_ERR, "setsockopt(listener, SOL_IP, IP_RECVORIGDSTADDR)");
- + goto fail;
- + }
- +
- + log_error(LOG_DEBUG, "redudp @ %s: TPROXY", red_inet_ntop(&instance->config.bindaddr, buf, sizeof(buf)));
- + }
- + else {
- + char buf1[RED_INET_ADDRSTRLEN], buf2[RED_INET_ADDRSTRLEN];
- + log_error(LOG_DEBUG, "redudp @ %s: destaddr=%s",
- + red_inet_ntop(&instance->config.bindaddr, buf1, sizeof(buf1)),
- + red_inet_ntop(&instance->config.destaddr, buf2, sizeof(buf2)));
- + }
- +
- error = bind(fd, (struct sockaddr*)&instance->config.bindaddr, sizeof(instance->config.bindaddr));
- if (error) {
- log_errno(LOG_ERR, "bind");
- diff --git a/redudp.h b/redudp.h
- index 308bd33..3f1d9d1 100644
- --- a/redudp.h
- +++ b/redudp.h
- @@ -24,6 +24,8 @@ typedef struct redudp_client_t {
- list_head list;
- redudp_instance *instance;
- struct sockaddr_in clientaddr;
- + struct sockaddr_in destaddr;
- + int sender_fd; // shared between several clients socket (bound to `destaddr`)
- struct event timeout;
- struct bufferevent *relay;
- struct event udprelay;
- diff --git a/utils.c b/utils.c
- index 6e1f3af..afdeea8 100644
- --- a/utils.c
- +++ b/utils.c
- @@ -26,17 +26,54 @@
- #include "utils.h"
- #include "redsocks.h" // for redsocks_close
-
- -int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr)
- +int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr, struct sockaddr_in *toaddr)
- {
- socklen_t addrlen = sizeof(*inaddr);
- ssize_t pktlen;
- -
- - pktlen = recvfrom(fd, buf, buflen, 0, (struct sockaddr*)inaddr, &addrlen);
- + struct msghdr msg;
- + struct iovec io;
- + char control[1024];
- +
- + memset(&msg, 0, sizeof(msg));
- + msg.msg_name = inaddr;
- + msg.msg_namelen = sizeof(*inaddr);
- + msg.msg_iov = &io;
- + msg.msg_iovlen = 1;
- + msg.msg_control = control;
- + msg.msg_controllen = sizeof(control);
- + io.iov_base = buf;
- + io.iov_len = buflen;
- +
- + pktlen = recvmsg(fd, &msg, 0);
- if (pktlen == -1) {
- log_errno(LOG_WARNING, "recvfrom");
- return -1;
- }
-
- + if (toaddr) {
- + memset(toaddr, 0, sizeof(*toaddr));
- + for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
- + if (
- + cmsg->cmsg_level == SOL_IP &&
- + cmsg->cmsg_type == IP_ORIGDSTADDR &&
- + cmsg->cmsg_len >= CMSG_LEN(sizeof(*toaddr))
- + ) {
- + struct sockaddr_in* cmsgaddr = (struct sockaddr_in*)CMSG_DATA(cmsg);
- + char buf[RED_INET_ADDRSTRLEN];
- + log_error(LOG_DEBUG, "IP_ORIGDSTADDR: %s", red_inet_ntop(cmsgaddr, buf, sizeof(buf)));
- + memcpy(toaddr, cmsgaddr, sizeof(*toaddr));
- + }
- + else {
- + log_error(LOG_WARNING, "unexepcted cmsg (level,type) = (%d,%d)",
- + cmsg->cmsg_level, cmsg->cmsg_type);
- + }
- + }
- + if (toaddr->sin_family != AF_INET) {
- + log_error(LOG_WARNING, "(SOL_IP, IP_ORIGDSTADDR) not found");
- + return -1;
- + }
- + }
- +
- if (addrlen != sizeof(*inaddr)) {
- log_error(LOG_WARNING, "unexpected address length %u instead of %zu", addrlen, sizeof(*inaddr));
- return -1;
- diff --git a/utils.h b/utils.h
- index d3af00f..c2277e9 100644
- --- a/utils.h
- +++ b/utils.h
- @@ -44,7 +44,7 @@ char *redsocks_evbuffer_readline(struct evbuffer *buf);
- struct bufferevent* red_connect_relay(struct sockaddr_in *addr, evbuffercb writecb, everrorcb errorcb, void *cbarg);
- int red_socket_geterrno(struct bufferevent *buffev);
- int red_is_socket_connected_ok(struct bufferevent *buffev);
- -int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr);
- +int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *fromaddr, struct sockaddr_in *toaddr);
-
- int fcntl_nonblock(int fd);
-
- --
- 1.9.1
-
|