diff options
Diffstat (limited to 'port_fwd.c')
| -rw-r--r-- | port_fwd.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/port_fwd.c b/port_fwd.c new file mode 100644 index 0000000..136a450 --- /dev/null +++ b/port_fwd.c @@ -0,0 +1,179 @@ +// 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" + +/** + * procfs_scan_listen() - Set bits for listening TCP or UDP sockets from procfs + * @proto: IPPROTO_TCP or IPPROTO_UDP + * @ip_version: IP version, V4 or V6 + * @ns: Use saved file descriptors for namespace if set + * @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(struct ctx *c, uint8_t proto, int ip_version, + int ns, uint8_t *map, const uint8_t *exclude) +{ + char *path, *line; + struct lineread lr; + unsigned long port; + unsigned int state; + int *fd; + + if (proto == IPPROTO_TCP) { + fd = &c->proc_net_tcp[ip_version][ns]; + if (ip_version == V4) + path = "/proc/net/tcp"; + else + path = "/proc/net/tcp6"; + } else { + fd = &c->proc_net_udp[ip_version][ns]; + if (ip_version == V4) + path = "/proc/net/udp"; + else + path = "/proc/net/udp6"; + } + + if (*fd != -1) { + if (lseek(*fd, 0, SEEK_SET)) { + warn("lseek() failed on %s: %s", path, strerror(errno)); + return; + } + } else if ((*fd = open(path, O_RDONLY | O_CLOEXEC)) < 0) { + 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 ((proto == IPPROTO_TCP && state != 0x0a) || + (proto == IPPROTO_UDP && state != 0x07)) + 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, IPPROTO_UDP, V4, ns, udp_map, udp_excl); + procfs_scan_listen(c, IPPROTO_UDP, V6, ns, udp_map, udp_excl); + + procfs_scan_listen(c, IPPROTO_TCP, V4, ns, udp_map, udp_excl); + procfs_scan_listen(c, IPPROTO_TCP, V6, ns, udp_map, udp_excl); + } else if (proto == IPPROTO_TCP) { + memset(tcp_map, 0, PORT_BITMAP_SIZE); + procfs_scan_listen(c, IPPROTO_TCP, V4, ns, tcp_map, tcp_excl); + procfs_scan_listen(c, IPPROTO_TCP, V6, ns, tcp_map, tcp_excl); + } +} + +/** + * struct get_bound_ports_ns_arg - Arguments for get_bound_ports_ns() + * @c: Execution context + * @proto: Protocol number (IPPROTO_TCP or IPPROTO_UDP) + */ +struct get_bound_ports_ns_arg { + struct ctx *c; + uint8_t proto; +}; + +/** + * get_bound_ports_ns() - Get maps of ports in namespace with bound sockets + * @arg: See struct get_bound_ports_ns_arg + * + * Return: 0 + */ +static int get_bound_ports_ns(void *arg) +{ + struct get_bound_ports_ns_arg *a = (struct get_bound_ports_ns_arg *)arg; + struct ctx *c = a->c; + + if (!c->pasta_netns_fd) + return 0; + + ns_enter(c); + get_bound_ports(c, 1, a->proto); + + return 0; +} + +/** + * port_fwd_init() - Initial setup for port forwarding + * @c: Execution context + */ +void port_fwd_init(struct ctx *c) +{ + struct get_bound_ports_ns_arg ns_ports_arg = { .c = c }; + + 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) { + ns_ports_arg.proto = IPPROTO_TCP; + NS_CALL(get_bound_ports_ns, &ns_ports_arg); + } + if (c->udp.fwd_in.f.mode == FWD_AUTO) { + ns_ports_arg.proto = IPPROTO_UDP; + NS_CALL(get_bound_ports_ns, &ns_ports_arg); + } + if (c->tcp.fwd_out.mode == FWD_AUTO) + get_bound_ports(c, 0, IPPROTO_TCP); + if (c->udp.fwd_out.f.mode == FWD_AUTO) + get_bound_ports(c, 0, IPPROTO_UDP); +} |