From 6b4e68383c66bd8a3863d9a708bae583d18dc056 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Thu, 17 Nov 2022 18:49:34 +0000 Subject: [PATCH] passt, tap: Add --fd option This passes a fully connected stream socket to passt. Signed-off-by: Richard W.M. Jones [sbrivio: reuse fd_tap instead of adding a new descriptor, imply --one-off on --fd, add to optstring and usage()] Signed-off-by: Stefano Brivio --- conf.c | 28 ++++++++++++++++++++++++++-- passt.1 | 10 ++++++++++ passt.c | 1 - passt.h | 2 +- tap.c | 9 +++++++++ 5 files changed, 46 insertions(+), 4 deletions(-) diff --git a/conf.c b/conf.c index 4721c97..c37552d 100644 --- a/conf.c +++ b/conf.c @@ -719,6 +719,7 @@ static void usage(const char *name) UNIX_SOCK_PATH, 1); } + info( " -F, --fd FD Use FD as pre-opened connected socket"); info( " -p, --pcap FILE Log tap-facing traffic to pcap file"); info( " -P, --pid FILE Write own PID to the given file"); info( " -m, --mtu MTU Assign MTU via DHCP/NDP"); @@ -1079,6 +1080,7 @@ void conf(struct ctx *c, int argc, char **argv) {"log-file", required_argument, NULL, 'l' }, {"help", no_argument, NULL, 'h' }, {"socket", required_argument, NULL, 's' }, + {"fd", required_argument, NULL, 'F' }, {"ns-ifname", required_argument, NULL, 'I' }, {"pcap", required_argument, NULL, 'p' }, {"pid", required_argument, NULL, 'P' }, @@ -1138,9 +1140,9 @@ void conf(struct ctx *c, int argc, char **argv) if (c->mode == MODE_PASTA) { c->no_dhcp_dns = c->no_dhcp_dns_search = 1; - optstring = "dqfel:hI:p:P:m:a:n:M:g:i:D:S:46t:u:T:U:"; + optstring = "dqfel:hF:I:p:P:m:a:n:M:g:i:D:S:46t:u:T:U:"; } else { - optstring = "dqfel:hs:p:P:m:a:n:M:g:i:D:S:461t:u:"; + optstring = "dqfel:hs:F:p:P:m:a:n:M:g:i:D:S:461t:u:"; } c->tcp.fwd_in.mode = c->tcp.fwd_out.mode = 0; @@ -1355,6 +1357,23 @@ void conf(struct ctx *c, int argc, char **argv) err("Invalid socket path: %s", optarg); usage(argv[0]); } + break; + case 'F': + if (c->fd_tap >= 0) { + err("Multiple --fd options given"); + usage(argv[0]); + } + + errno = 0; + c->fd_tap = strtol(optarg, NULL, 0); + + if (c->fd_tap < 0 || errno) { + err("Invalid --fd: %s", optarg); + usage(argv[0]); + } + + c->one_off = true; + break; case 'I': if (*c->pasta_ifn) { @@ -1590,6 +1609,11 @@ void conf(struct ctx *c, int argc, char **argv) usage(argv[0]); } + if (*c->sock_path && c->fd_tap >= 0) { + err("Options --socket and --fd are mutually exclusive"); + usage(argv[0]); + } + ret = conf_ugid(runas, &uid, &gid); if (ret) usage(argv[0]); diff --git a/passt.1 b/passt.1 index e34a3e0..528763b 100644 --- a/passt.1 +++ b/passt.1 @@ -297,6 +297,16 @@ Path for UNIX domain socket used by \fBqemu\fR(1) or \fBqrap\fR(1) to connect to Default is to probe a free socket, not accepting connections, starting from \fI/tmp/passt_1.socket\fR to \fI/tmp/passt_64.socket\fR. +.TP +.BR \-F ", " \-\-fd " " \fIFD +Pass a pre-opened, connected socket to \fBpasst\fR. Usually the socket is opened +in the parent process and \fBpasst\fR inherits it when run as a child. This +allows the parent process to open sockets using another address family or +requiring special privileges. + +This option implies the behaviour described for \-\-one-off, once this socket +is closed. + .TP .BR \-1 ", " \-\-one-off Quit after handling a single client connection, that is, once the client closes diff --git a/passt.c b/passt.c index 7d323c2..8b2c50d 100644 --- a/passt.c +++ b/passt.c @@ -255,7 +255,6 @@ int main(int argc, char **argv) quit_fd = pasta_netns_quit_init(&c); - c.fd_tap = c.fd_tap_listen = -1; tap_sock_init(&c); clock_gettime(CLOCK_MONOTONIC, &now); diff --git a/passt.h b/passt.h index 6649c0a..ca25b90 100644 --- a/passt.h +++ b/passt.h @@ -159,7 +159,7 @@ struct ip6_ctx { * @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: File descriptor for AF_UNIX socket or tuntap device + * @fd_tap: AF_UNIX socket, tuntap device, or pre-opened socket * @mac: Host MAC address * @mac_guest: MAC address of guest or namespace, seen or configured * @ifi4: Index of routable interface for IPv4, 0 if IPv4 disabled diff --git a/tap.c b/tap.c index 5a20b75..2cfd82b 100644 --- a/tap.c +++ b/tap.c @@ -1069,6 +1069,15 @@ void tap_sock_init(struct ctx *c) } if (c->fd_tap != -1) { + if (c->one_off) { /* Passed as --fd */ + struct epoll_event ev = { 0 }; + + ev.data.fd = c->fd_tap; + ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP; + epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev); + return; + } + epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL); close(c->fd_tap); c->fd_tap = -1;