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| | // SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* port_fwd.c - Port forwarding helpers
*
* Copyright Red Hat
* Author: Stefano Brivio <sbrivio@redhat.com>
* Author: David Gibson <david@gibson.dropbear.id.au>
*/
#include <stdint.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include "util.h"
#include "port_fwd.h"
#include "passt.h"
#include "lineread.h"
#define UDP_LISTEN 0x07
#define TCP_LISTEN 0x0a
/**
* procfs_scan_listen() - Set bits for listening TCP or UDP sockets from procfs
* @fd: fd for relevant /proc/net file
* @lstate: Code for listening state to scan for
* @map: Bitmap where numbers of ports in listening state will be set
* @exclude: Bitmap of ports to exclude from setting (and clear)
*
* #syscalls:pasta lseek
* #syscalls:pasta ppc64le:_llseek ppc64:_llseek armv6l:_llseek armv7l:_llseek
*/
static void procfs_scan_listen(int fd, unsigned int lstate,
uint8_t *map, const uint8_t *exclude)
{
struct lineread lr;
unsigned long port;
unsigned int state;
char *line;
if (lseek(fd, 0, SEEK_SET)) {
warn("lseek() failed on /proc/net file: %s", strerror(errno));
return;
}
lineread_init(&lr, fd);
lineread_get(&lr, &line); /* throw away header */
while (lineread_get(&lr, &line) > 0) {
/* NOLINTNEXTLINE(cert-err34-c): != 2 if conversion fails */
if (sscanf(line, "%*u: %*x:%lx %*x:%*x %x", &port, &state) != 2)
continue;
/* See enum in kernel's include/net/tcp_states.h */
if (state != lstate)
continue;
if (bitmap_isset(exclude, port))
bitmap_clear(map, port);
else
bitmap_set(map, port);
}
}
/**
* get_bound_ports() - Get maps of ports with bound sockets
* @c: Execution context
* @ns: If set, set bitmaps for ports to tap/ns -- to init otherwise
* @proto: Protocol number (IPPROTO_TCP or IPPROTO_UDP)
*/
void get_bound_ports(struct ctx *c, int ns, uint8_t proto)
{
uint8_t *udp_map, *udp_excl, *tcp_map, *tcp_excl;
if (ns) {
udp_map = c->udp.fwd_in.f.map;
udp_excl = c->udp.fwd_out.f.map;
tcp_map = c->tcp.fwd_in.map;
tcp_excl = c->tcp.fwd_out.map;
} else {
udp_map = c->udp.fwd_out.f.map;
udp_excl = c->udp.fwd_in.f.map;
tcp_map = c->tcp.fwd_out.map;
tcp_excl = c->tcp.fwd_in.map;
}
if (proto == IPPROTO_UDP) {
memset(udp_map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(c->proc_net_udp[V4][ns],
UDP_LISTEN, udp_map, udp_excl);
procfs_scan_listen(c->proc_net_udp[V6][ns],
UDP_LISTEN, udp_map, udp_excl);
procfs_scan_listen(c->proc_net_tcp[V4][ns],
TCP_LISTEN, udp_map, udp_excl);
procfs_scan_listen(c->proc_net_tcp[V6][ns],
TCP_LISTEN, udp_map, udp_excl);
} else if (proto == IPPROTO_TCP) {
memset(tcp_map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(c->proc_net_tcp[V4][ns],
TCP_LISTEN, tcp_map, tcp_excl);
procfs_scan_listen(c->proc_net_tcp[V6][ns],
TCP_LISTEN, tcp_map, tcp_excl);
}
}
/**
* port_fwd_init() - Initial setup for port forwarding
* @c: Execution context
*/
void port_fwd_init(struct ctx *c)
{
const int flags = O_RDONLY | O_CLOEXEC;
c->proc_net_tcp[V4][0] = c->proc_net_tcp[V4][1] = -1;
c->proc_net_tcp[V6][0] = c->proc_net_tcp[V6][1] = -1;
c->proc_net_udp[V4][0] = c->proc_net_udp[V4][1] = -1;
c->proc_net_udp[V6][0] = c->proc_net_udp[V6][1] = -1;
if (c->tcp.fwd_in.mode == FWD_AUTO) {
c->proc_net_tcp[V4][1] = open_in_ns(c, "/proc/net/tcp", flags);
c->proc_net_tcp[V6][1] = open_in_ns(c, "/proc/net/tcp6", flags);
get_bound_ports(c, 1, IPPROTO_TCP);
}
if (c->udp.fwd_in.f.mode == FWD_AUTO) {
c->proc_net_udp[V4][1] = open_in_ns(c, "/proc/net/udp", flags);
c->proc_net_udp[V6][1] = open_in_ns(c, "/proc/net/udp6", flags);
get_bound_ports(c, 1, IPPROTO_UDP);
}
if (c->tcp.fwd_out.mode == FWD_AUTO) {
c->proc_net_tcp[V4][0] = open("/proc/net/tcp", flags);
c->proc_net_tcp[V6][0] = open("/proc/net/tcp6", flags);
get_bound_ports(c, 0, IPPROTO_TCP);
}
if (c->udp.fwd_out.f.mode == FWD_AUTO) {
c->proc_net_udp[V4][0] = open("/proc/net/udp", flags);
c->proc_net_udp[V6][0] = open("/proc/net/udp6", flags);
get_bound_ports(c, 0, IPPROTO_UDP);
}
}
|