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From: "Richard W.M. Jones" <rjones@redhat.com>
To: sbrivio@redhat.com
Subject: [PATCH passt v2 3/7] passt, tap: Add --fd option
Date: Thu, 17 Nov 2022 18:49:34 +0000
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This passes a fully connected stream socket to passt.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
[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 <sbrivio@redhat.com>
---
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 a995eb7..9ec346f 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 d26af58..9998127 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;
--
2.37.0.rc2