From nobody Mon Apr 29 06:23:38 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1486202712133692.4807906539162; Sat, 4 Feb 2017 02:05:12 -0800 (PST) Received: from localhost ([::1]:38597 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cZxDR-0003ZX-Se for importer@patchew.org; Sat, 04 Feb 2017 05:05:09 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37396) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cZxBl-0002eH-H6 for qemu-devel@nongnu.org; Sat, 04 Feb 2017 05:03:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cZxBj-0003ma-JR for qemu-devel@nongnu.org; Sat, 04 Feb 2017 05:03:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35376) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cZxBj-0003mB-Bk for qemu-devel@nongnu.org; Sat, 04 Feb 2017 05:03:23 -0500 Received: from smtp.corp.redhat.com (int-mx16.intmail.prod.int.phx2.redhat.com [10.5.11.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 733BB3A76A6; Sat, 4 Feb 2017 10:03:23 +0000 (UTC) Received: from moo.home.annexia.org (ovpn-116-182.ams2.redhat.com [10.36.116.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3097723AF; Sat, 4 Feb 2017 10:03:21 +0000 (UTC) From: "Richard W.M. Jones" To: pbonzini@redhat.com Date: Sat, 4 Feb 2017 10:03:17 +0000 Message-Id: <20170204100317.32425-2-rjones@redhat.com> In-Reply-To: <20170204100317.32425-1-rjones@redhat.com> References: <20170204100317.32425-1-rjones@redhat.com> X-Scanned-By: MIMEDefang 2.74 on 10.5.11.28 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Sat, 04 Feb 2017 10:03:23 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v5] qemu-nbd: Implement socket activation. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stefanha@gmail.com, qemu-devel@nongnu.org, armbru@redhat.com, dplotnikov@virtuozzo.com, rkagan@virtuozzo.com, den@openvz.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Socket activation (sometimes known as systemd socket activation) allows an Internet superserver to pass a pre-opened listening socket to the process, instead of having qemu-nbd open a socket itself. This is done via the LISTEN_FDS and LISTEN_PID environment variables, and a standard file descriptor range. This change partially implements socket activation for qemu-nbd. If the environment variables are set correctly, then socket activation will happen automatically, otherwise everything works as before. The limitation is that LISTEN_FDS must be 1. Signed-off-by: Richard W.M. Jones. --- qemu-nbd.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++= ---- 1 file changed, 163 insertions(+), 9 deletions(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index c734f62..e4fede6 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -463,6 +463,135 @@ static QCryptoTLSCreds *nbd_get_tls_creds(const char = *id, Error **errp) return creds; } =20 +static void setup_address_and_port(const char **address, const char **port) +{ + if (*address =3D=3D NULL) { + *address =3D "0.0.0.0"; + } + + if (*port =3D=3D NULL) { + *port =3D stringify(NBD_DEFAULT_PORT); + } +} + +#define FIRST_SOCKET_ACTIVATION_FD 3 /* defined by systemd ABI */ + +#ifndef _WIN32 +/* + * Check if socket activation was requested via use of the + * LISTEN_FDS and LISTEN_PID environment variables. + * + * Returns 0 if no socket activation, or the number of FDs. + */ +static unsigned int check_socket_activation(void) +{ + const char *s; + unsigned long pid; + unsigned long nr_fds; + unsigned int i; + int fd; + int err; + + s =3D getenv("LISTEN_PID"); + if (s =3D=3D NULL) { + return 0; + } + err =3D qemu_strtoul(s, NULL, 10, &pid); + if (err) { + if (verbose) { + fprintf(stderr, "malformed %s environment variable (ignored)\n= ", + "LISTEN_PID"); + } + return 0; + } + if (pid !=3D getpid()) { + if (verbose) { + fprintf(stderr, "%s was not for us (ignored)\n", + "LISTEN_PID"); + } + return 0; + } + + s =3D getenv("LISTEN_FDS"); + if (s =3D=3D NULL) { + return 0; + } + err =3D qemu_strtoul(s, NULL, 10, &nr_fds); + if (err) { + if (verbose) { + fprintf(stderr, "malformed %s environment variable (ignored)\n= ", + "LISTEN_FDS"); + } + return 0; + } + assert(nr_fds <=3D UINT_MAX); + + /* A limitation of current qemu-nbd is that it can only listen on + * a single socket. When that limitation is lifted, we can change + * this function to allow LISTEN_FDS > 1, and remove the assertion + * in the main function below. + */ + if (nr_fds > 1) { + error_report("qemu-nbd does not support socket activation with %s = > 1", + "LISTEN_FDS"); + exit(EXIT_FAILURE); + } + + /* So these are not passed to any child processes we might start. */ + unsetenv("LISTEN_FDS"); + unsetenv("LISTEN_PID"); + + /* So the file descriptors don't leak into child processes. */ + for (i =3D 0; i < nr_fds; ++i) { + fd =3D FIRST_SOCKET_ACTIVATION_FD + i; + if (fcntl(fd, F_SETFD, FD_CLOEXEC) =3D=3D -1) { + /* If we cannot set FD_CLOEXEC then it probably means the file + * descriptor is invalid, so socket activation has gone wrong + * and we should exit. + */ + error_report("Socket activation failed: " + "invalid file descriptor fd =3D %d: %m", + fd); + exit(EXIT_FAILURE); + } + } + + return (unsigned int) nr_fds; +} + +#else /* !_WIN32 */ +static unsigned int check_socket_activation(void) +{ + return 0; +} +#endif + +/* + * Check socket parameters compatibility when socket activation is used. + */ +static const char *socket_activation_validate_opts(const char *device, + const char *sockpath, + const char *address, + const char *port) +{ + if (device !=3D NULL) { + return "NBD device can't be set when using socket activation"; + } + + if (sockpath !=3D NULL) { + return "Unix socket can't be set when using socket activation"; + } + + if (address !=3D NULL) { + return "The interface can't be set when using socket activation"; + } + + if (port !=3D NULL) { + return "TCP port number can't be set when using socket activation"; + } + + return NULL; +} =20 int main(int argc, char **argv) { @@ -471,7 +600,7 @@ int main(int argc, char **argv) off_t dev_offset =3D 0; uint16_t nbdflags =3D 0; bool disconnect =3D false; - const char *bindto =3D "0.0.0.0"; + const char *bindto =3D NULL; const char *port =3D NULL; char *sockpath =3D NULL; char *device =3D NULL; @@ -533,6 +662,7 @@ int main(int argc, char **argv) char *trace_file =3D NULL; bool fork_process =3D false; int old_stderr =3D -1; + unsigned socket_activation; =20 /* The client thread uses SIGTERM to interrupt the server. A signal * handler ensures that "qemu-nbd -v -c" exits with a nice status code. @@ -751,6 +881,19 @@ int main(int argc, char **argv) trace_init_file(trace_file); qemu_set_log(LOG_TRACE); =20 + socket_activation =3D check_socket_activation(); + if (socket_activation =3D=3D 0) { + setup_address_and_port(&bindto, &port); + } else { + /* Using socket activation - check user didn't use -p etc. */ + const char *err_msg =3D socket_activation_validate_opts(device, so= ckpath, + bindto, port= ); + if (err_msg !=3D NULL) { + error_report("%s", err_msg); + exit(EXIT_FAILURE); + } + } + if (tlscredsid) { if (sockpath) { error_report("TLS is only supported with IPv4/IPv6"); @@ -855,7 +998,25 @@ int main(int argc, char **argv) snprintf(sockpath, 128, SOCKET_PATH, basename(device)); } =20 - saddr =3D nbd_build_socket_address(sockpath, bindto, port); + if (socket_activation =3D=3D 0) { + server_ioc =3D qio_channel_socket_new(); + saddr =3D nbd_build_socket_address(sockpath, bindto, port); + if (qio_channel_socket_listen_sync(server_ioc, saddr, &local_err) = < 0) { + object_unref(OBJECT(server_ioc)); + error_report_err(local_err); + return 1; + } + } else { + /* See comment in check_socket_activation above. */ + assert(socket_activation =3D=3D 1); + server_ioc =3D qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_F= D, + &local_err); + if (server_ioc =3D=3D NULL) { + error_report("Failed to use socket activation: %s", + error_get_pretty(local_err)); + exit(EXIT_FAILURE); + } + } =20 if (qemu_init_main_loop(&local_err)) { error_report_err(local_err); @@ -950,13 +1111,6 @@ int main(int argc, char **argv) exit(EXIT_FAILURE); } =20 - server_ioc =3D qio_channel_socket_new(); - if (qio_channel_socket_listen_sync(server_ioc, saddr, &local_err) < 0)= { - object_unref(OBJECT(server_ioc)); - error_report_err(local_err); - return 1; - } - if (device) { int ret; =20 --=20 2.10.2