[libvirt PATCH v2 4/9] qemu: add a DBus daemon helper unit

From: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; Add a unit to start & stop a private dbus-daemon. The daemon is meant to be started on demand, and associated with a QEMU process. It should be stopped when the QEMU process is stopped. The current policy is permissive like a session bus. Stricter policies can be added later, following recommendations from: https://git.qemu.org/?p=qemu.git;a=blob;f=docs/interop/dbus.rst Signed-off-by: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; --- po/POTFILES.in | 1 + src/qemu/Makefile.inc.am | 2 + src/qemu/qemu_dbus.c | 282 +++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_dbus.h | 33 +++++ src/qemu/qemu_domain.h | 2 + 5 files changed, 320 insertions(+) create mode 100644 src/qemu/qemu_dbus.c create mode 100644 src/qemu/qemu_dbus.h diff --git a/po/POTFILES.in b/po/POTFILES.in index 2d54623dc7..fe361204bb 100644 --- a/po/POTFILES.in +++ b/po/POTFILES.in @@ -150,6 +150,7 @@ @SRCDIR(a)/src/qemu/qemu_checkpoint.c @SRCDIR(a)/src/qemu/qemu_command.c @SRCDIR(a)/src/qemu/qemu_conf.c +@SRCDIR(a)/src/qemu/qemu_dbus.c @SRCDIR(a)/src/qemu/qemu_domain.c @SRCDIR(a)/src/qemu/qemu_domain_address.c @SRCDIR(a)/src/qemu/qemu_driver.c diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am index 2b8517ecff..94a333f855 100644 --- a/src/qemu/Makefile.inc.am +++ b/src/qemu/Makefile.inc.am @@ -13,6 +13,8 @@ QEMU_DRIVER_SOURCES = \ qemu/qemu_capabilities.h \ qemu/qemu_command.c \ qemu/qemu_command.h \ + qemu/qemu_dbus.c \ + qemu/qemu_dbus.h \ qemu/qemu_domain.c \ qemu/qemu_domain.h \ qemu/qemu_domain_address.c \ diff --git a/src/qemu/qemu_dbus.c b/src/qemu/qemu_dbus.c new file mode 100644 index 0000000000..383efa0209 --- /dev/null +++ b/src/qemu/qemu_dbus.c @@ -0,0 +1,282 @@ +/* + * qemu_dbus.c: QEMU dbus daemon + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + */ + +#include <config.h> + +#include "qemu_extdevice.h" +#include "qemu_dbus.h" +#include "qemu_security.h" + +#include "viralloc.h" +#include "virlog.h" +#include "virstring.h" +#include "virtime.h" +#include "virpidfile.h" + +#define VIR_FROM_THIS VIR_FROM_NONE + +VIR_LOG_INIT("qemu.dbus"); + + +int +qemuDBusPrepareHost(virQEMUDriverPtr driver) +{ + g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver); + + return virDirCreate(cfg->dbusStateDir, 0770, cfg->user, cfg->group, + VIR_DIR_CREATE_ALLOW_EXIST); +} + + +static char * +qemuDBusCreatePidFilename(virQEMUDriverConfigPtr cfg, + const char *shortName) +{ + g_autofree char *name = g_strdup_printf("%s-dbus", shortName); + + return virPidFileBuildPath(cfg->dbusStateDir, name); +} + + +static char * +qemuDBusCreateFilename(const char *stateDir, + const char *shortName, + const char *ext) +{ + g_autofree char *name = g_strdup_printf("%s-dbus", shortName); + + return virFileBuildPath(stateDir, name, ext); +} + + +static char * +qemuDBusCreateSocketPath(virQEMUDriverConfigPtr cfg, + const char *shortName) +{ + return qemuDBusCreateFilename(cfg->dbusStateDir, shortName, ".sock"); +} + + +static char * +qemuDBusCreateConfPath(virQEMUDriverConfigPtr cfg, + const char *shortName) +{ + return qemuDBusCreateFilename(cfg->dbusStateDir, shortName, ".conf"); +} + + +char * +qemuDBusGetAddress(virQEMUDriverPtr driver, + virDomainObjPtr vm) +{ + g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver); + g_autofree char *shortName = virDomainDefGetShortName(vm->def); + g_autofree char *path = NULL; + + if (!shortName) + return NULL; + + path = qemuDBusCreateSocketPath(cfg, shortName); + + return g_strdup_printf("unix:path=%s", path); +} + + +static int +qemuDBusWriteConfig(const char *filename, const char *path) +{ + virBuffer buf = VIR_BUFFER_INITIALIZER; + g_autofree char *config = NULL; + + virBufferAddLit(&buf, "<!DOCTYPE busconfig PUBLIC \"-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN\"\n"); + virBufferAddLit(&buf, " \"http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd\">\n"); + virBufferAddLit(&buf, "<busconfig>\n"); + virBufferAdjustIndent(&buf, 2); + + virBufferAddLit(&buf, "<type>org.libvirt.qemu</type>\n"); + virBufferAsprintf(&buf, "<listen>unix:path=%s</listen>\n", path); + virBufferAddLit(&buf, "<auth>EXTERNAL</auth>\n"); + + virBufferAddLit(&buf, "<policy context='default'>\n"); + virBufferAdjustIndent(&buf, 2); + virBufferAddLit(&buf, "<!-- Allow everything to be sent -->\n"); + virBufferAddLit(&buf, "<allow send_destination='*' eavesdrop='true'/>\n"); + virBufferAddLit(&buf, "<!-- Allow everything to be received -->\n"); + virBufferAddLit(&buf, "<allow eavesdrop='true'/>\n"); + virBufferAddLit(&buf, "<!-- Allow anyone to own anything -->\n"); + virBufferAddLit(&buf, "<allow own='*'/>\n"); + virBufferAdjustIndent(&buf, -2); + virBufferAddLit(&buf, "</policy>\n"); + + virBufferAddLit(&buf, "<include if_selinux_enabled='yes' selinux_root_relative='yes'>contexts/dbus_contexts</include>\n"); + + virBufferAdjustIndent(&buf, -2); + virBufferAddLit(&buf, "</busconfig>\n"); + + config = virBufferContentAndReset(&buf); + + return virFileWriteStr(filename, config, 0600); +} + + +void +qemuDBusStop(virQEMUDriverPtr driver, + virDomainObjPtr vm) +{ + g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver); + qemuDomainObjPrivatePtr priv = vm->privateData; + g_autofree char *shortName = NULL; + g_autofree char *pidfile = NULL; + g_autofree char *configfile = NULL; + + if (!(shortName = virDomainDefGetShortName(vm->def))) + return; + + pidfile = qemuDBusCreatePidFilename(cfg, shortName); + configfile = qemuDBusCreateConfPath(cfg, shortName); + + if (virPidFileForceCleanupPath(pidfile) < 0) { + VIR_WARN("Unable to kill dbus-daemon process"); + } else { + if (unlink(configfile) < 0 && + errno != ENOENT) { + virReportSystemError(errno, + _("Unable to remove stale configfile %s"), + pidfile); + + } + priv->dbusDaemonRunning = false; + } +} + + +int +qemuDBusStart(virQEMUDriverPtr driver, + virDomainObjPtr vm) +{ + g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver); + qemuDomainObjPrivatePtr priv = vm->privateData; + g_autoptr(virCommand) cmd = NULL; + g_autofree char *shortName = NULL; + g_autofree char *pidfile = NULL; + g_autofree char *configfile = NULL; + g_autofree char *sockpath = NULL; + virTimeBackOffVar timebackoff; + const unsigned long long timeout = 500 * 1000; /* ms */ + VIR_AUTOCLOSE errfd = -1; + int cmdret = 0; + int exitstatus = 0; + pid_t cpid = -1; + int ret = -1; + + if (!virFileIsExecutable(cfg->dbusDaemonName)) { + virReportSystemError(errno, + _("'%s' is not a suitable dbus-daemon"), + cfg->dbusDaemonName); + return -1; + } + + if (!(shortName = virDomainDefGetShortName(vm->def))) + return -1; + + pidfile = qemuDBusCreatePidFilename(cfg, shortName); + configfile = qemuDBusCreateConfPath(cfg, shortName); + sockpath = qemuDBusCreateSocketPath(cfg, shortName); + + if (qemuDBusWriteConfig(configfile, sockpath) < 0) { + virReportSystemError(errno, _("Failed to write '%s'"), configfile); + return -1; + } + + if (qemuSecurityDomainSetPathLabel(driver, vm, configfile, false) < 0) + goto cleanup; + + cmd = virCommandNew(cfg->dbusDaemonName); + virCommandClearCaps(cmd); + virCommandSetPidFile(cmd, pidfile); + virCommandSetErrorFD(cmd, &errfd); + virCommandDaemonize(cmd); + virCommandAddArgFormat(cmd, "--config-file=%s", configfile); + + if (qemuSecurityCommandRun(driver, vm, cmd, -1, -1, + &exitstatus, &cmdret) < 0) + goto cleanup; + + if (cmdret < 0 || exitstatus != 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Could not start dbus-daemon. exitstatus: %d"), exitstatus); + goto cleanup; + } + + if (virPidFileReadPath(pidfile, &cpid) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("dbus-daemon %s didn't show up"), + cfg->dbusDaemonName); + goto cleanup; + } + + if (virTimeBackOffStart(&timebackoff, 1, timeout) < 0) + goto cleanup; + while (virTimeBackOffWait(&timebackoff)) { + char errbuf[1024] = { 0 }; + + if (virFileExists(sockpath)) + break; + + if (virProcessKill(cpid, 0) == 0) + continue; + + if (saferead(errfd, errbuf, sizeof(errbuf) - 1) < 0) { + virReportSystemError(errno, + _("dbus-daemon %s died unexpectedly"), + cfg->dbusDaemonName); + } else { + virReportError(VIR_ERR_OPERATION_FAILED, + _("dbus-daemon died and reported: %s"), errbuf); + } + + goto cleanup; + } + + if (!virFileExists(sockpath)) { + virReportError(VIR_ERR_OPERATION_TIMEOUT, + _("DBus daemon %s didn't show up"), + cfg->dbusDaemonName); + goto cleanup; + } + + if (priv->cgroup && + virCgroupAddProcess(priv->cgroup, cpid) < 0) + goto cleanup; + + if (qemuSecurityDomainSetPathLabel(driver, vm, sockpath, false) < 0) + goto cleanup; + + priv->dbusDaemonRunning = true; + ret = 0; + cleanup: + if (ret < 0) { + virCommandAbort(cmd); + if (cpid >= 0) + virProcessKillPainfully(cpid, true); + unlink(pidfile); + unlink(configfile); + unlink(sockpath); + } + return ret; +} diff --git a/src/qemu/qemu_dbus.h b/src/qemu/qemu_dbus.h new file mode 100644 index 0000000000..d6cb1bc84a --- /dev/null +++ b/src/qemu/qemu_dbus.h @@ -0,0 +1,33 @@ +/* + * qemu_dbus.h: QEMU dbus daemon + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + */ + +#pragma once + +#include "qemu_conf.h" +#include "qemu_domain.h" + +int qemuDBusPrepareHost(virQEMUDriverPtr driver); + +char *qemuDBusGetAddress(virQEMUDriverPtr driver, + virDomainObjPtr vm); + +int qemuDBusStart(virQEMUDriverPtr driver, + virDomainObjPtr vm); + +void qemuDBusStop(virQEMUDriverPtr driver, + virDomainObjPtr vm); diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index c4fd7ac302..97e52b7a81 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -417,6 +417,8 @@ struct _qemuDomainObjPrivate { /* running backup job */ virDomainBackupDefPtr backup; + + bool dbusDaemonRunning; }; #define QEMU_DOMAIN_PRIVATE(vm) \ -- 2.25.0.rc2.1.g09a9a1a997