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port_fwd: Move port scanning /proc fds into struct port_fwd

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Currently we store /proc/net fds used to implement automatic port
forwarding in the proc_net_{tcp,udp} fields of the main context structure.
However, in fact each of those is associated with a particular direction
of forwarding, and we already have struct port_fwd which collects all
other information related to a particular direction of port forwarding.

We can simplify things a bit by moving the /proc fds into struct port_fwd.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2023-11-03 13:23:02 +11:00 committed by Stefano Brivio
parent 1a40d00895
commit dcf5c0eb1e
3 changed files with 36 additions and 35 deletions
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5
passt.h
View file

@ -203,8 +203,6 @@ struct ip6_ctx {
* @no_netns_quit: In pasta mode, don't exit if fs-bound namespace is gone
* @netns_base: Base name for fs-bound namespace, if any, in pasta mode
* @netns_dir: Directory of fs-bound namespace, if any, in pasta mode
* @proc_net_tcp: Stored handles for /proc/net/tcp{,6} in init and ns
* @proc_net_udp: Stored handles for /proc/net/udp{,6} in init and ns
* @epollfd: File descriptor for epoll instance
* @fd_tap_listen: File descriptor for listening AF_UNIX socket, if any
* @fd_tap: AF_UNIX socket, tuntap device, or pre-opened socket
@ -258,9 +256,6 @@ struct ctx {
char netns_base[PATH_MAX];
char netns_dir[PATH_MAX];
int proc_net_tcp[IP_VERSIONS][2];
int proc_net_udp[IP_VERSIONS][2];
int epollfd;
int fd_tap_listen;
int fd_tap;

62
port_fwd.c
View file

@ -74,19 +74,19 @@ static void procfs_scan_listen(int fd, unsigned int lstate,
*/
void get_bound_ports_tcp(struct ctx *c, int ns)
{
uint8_t *map, *excl;
struct port_fwd *fwd, *rev;
if (ns) {
map = c->tcp.fwd_in.map;
excl = c->tcp.fwd_out.map;
fwd = &c->tcp.fwd_in;
rev = &c->tcp.fwd_out;
} else {
map = c->tcp.fwd_out.map;
excl = c->tcp.fwd_in.map;
fwd = &c->tcp.fwd_out;
rev = &c->tcp.fwd_in;
}
memset(map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(c->proc_net_tcp[V4][ns], TCP_LISTEN, map, excl);
procfs_scan_listen(c->proc_net_tcp[V6][ns], TCP_LISTEN, map, excl);
memset(fwd->map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(fwd->scan4, TCP_LISTEN, fwd->map, rev->map);
procfs_scan_listen(fwd->scan6, TCP_LISTEN, fwd->map, rev->map);
}
/**
@ -96,27 +96,29 @@ void get_bound_ports_tcp(struct ctx *c, int ns)
*/
void get_bound_ports_udp(struct ctx *c, int ns)
{
uint8_t *map, *excl;
struct port_fwd *fwd, *rev, *tcp;
if (ns) {
map = c->udp.fwd_in.f.map;
excl = c->udp.fwd_out.f.map;
fwd = &c->udp.fwd_in.f;
rev = &c->udp.fwd_out.f;
tcp = &c->tcp.fwd_in;
} else {
map = c->udp.fwd_out.f.map;
excl = c->udp.fwd_in.f.map;
fwd = &c->udp.fwd_out.f;
rev = &c->udp.fwd_in.f;
tcp = &c->tcp.fwd_out;
}
memset(map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(c->proc_net_udp[V4][ns], UDP_LISTEN, map, excl);
procfs_scan_listen(c->proc_net_udp[V6][ns], UDP_LISTEN, map, excl);
memset(fwd->map, 0, PORT_BITMAP_SIZE);
procfs_scan_listen(fwd->scan4, UDP_LISTEN, fwd->map, rev->map);
procfs_scan_listen(fwd->scan6, UDP_LISTEN, fwd->map, rev->map);
/* Also forward UDP ports with the same numbers as bound TCP ports.
* This is useful for a handful of protocols (e.g. iperf3) where a TCP
* control port is used to set up transfers on a corresponding UDP
* port.
*/
procfs_scan_listen(c->proc_net_tcp[V4][ns], TCP_LISTEN, map, excl);
procfs_scan_listen(c->proc_net_tcp[V6][ns], TCP_LISTEN, map, excl);
procfs_scan_listen(tcp->scan4, TCP_LISTEN, fwd->map, rev->map);
procfs_scan_listen(tcp->scan6, TCP_LISTEN, fwd->map, rev->map);
}
/**
@ -127,29 +129,29 @@ 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;
c->tcp.fwd_in.scan4 = c->tcp.fwd_in.scan6 = -1;
c->tcp.fwd_out.scan4 = c->tcp.fwd_out.scan6 = -1;
c->udp.fwd_in.f.scan4 = c->udp.fwd_in.f.scan6 = -1;
c->udp.fwd_out.f.scan4 = c->udp.fwd_out.f.scan6 = -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);
c->tcp.fwd_in.scan4 = open_in_ns(c, "/proc/net/tcp", flags);
c->tcp.fwd_in.scan6 = open_in_ns(c, "/proc/net/tcp6", flags);
get_bound_ports_tcp(c, 1);
}
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);
c->udp.fwd_in.f.scan4 = open_in_ns(c, "/proc/net/udp", flags);
c->udp.fwd_in.f.scan6 = open_in_ns(c, "/proc/net/udp6", flags);
get_bound_ports_udp(c, 1);
}
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);
c->tcp.fwd_out.scan4 = open("/proc/net/tcp", flags);
c->tcp.fwd_out.scan6 = open("/proc/net/tcp6", flags);
get_bound_ports_tcp(c, 0);
}
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);
c->udp.fwd_out.f.scan4 = open("/proc/net/udp", flags);
c->udp.fwd_out.f.scan6 = open("/proc/net/udp6", flags);
get_bound_ports_udp(c, 0);
}
}

4
port_fwd.h
View file

@ -22,11 +22,15 @@ enum port_fwd_mode {
/**
* port_fwd - Describes port forwarding for one protocol and direction
* @mode: Overall forwarding mode (all, none, auto, specific ports)
* @scan4: /proc/net fd to scan for IPv4 ports when in AUTO mode
* @scan6: /proc/net fd to scan for IPv6 ports when in AUTO mode
* @map: Bitmap describing which ports are forwarded
* @delta: Offset between the original destination and mapped port number
*/
struct port_fwd {
enum port_fwd_mode mode;
int scan4;
int scan6;
uint8_t map[PORT_BITMAP_SIZE];
in_port_t delta[NUM_PORTS];
};