[libvirt] [PATCH 4/8] 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; --- src/qemu/Makefile.inc.am | 4 + src/qemu/qemu_dbus.c | 299 +++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_dbus.h | 40 ++++++ src/qemu/qemu_domain.c | 2 + src/qemu/qemu_domain.h | 3 + tests/Makefile.am | 1 + 6 files changed, 349 insertions(+) create mode 100644 src/qemu/qemu_dbus.c create mode 100644 src/qemu/qemu_dbus.h diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am index 028ab9043c..833638ec3c 100644 --- a/src/qemu/Makefile.inc.am +++ b/src/qemu/Makefile.inc.am @@ -69,6 +69,8 @@ QEMU_DRIVER_SOURCES = \ qemu/qemu_checkpoint.h \ qemu/qemu_backup.c \ qemu/qemu_backup.h \ + qemu/qemu_dbus.c \ + qemu/qemu_dbus.h \ $(NULL) @@ -93,6 +95,7 @@ libvirt_driver_qemu_impl_la_CFLAGS = \ $(LIBNL_CFLAGS) \ $(SELINUX_CFLAGS) \ $(XDR_CFLAGS) \ + $(DBUS_CFLAGS) \ -I$(srcdir)/access \ -I$(builddir)/access \ -I$(srcdir)/conf \ @@ -105,6 +108,7 @@ libvirt_driver_qemu_impl_la_LIBADD = \ $(GNUTLS_LIBS) \ $(LIBNL_LIBS) \ $(SELINUX_LIBS) \ + $(DBUS_LIBS) \ $(LIBXML_LIBS) \ $(NULL) libvirt_driver_qemu_impl_la_SOURCES = $(QEMU_DRIVER_SOURCES) diff --git a/src/qemu/qemu_dbus.c b/src/qemu/qemu_dbus.c new file mode 100644 index 0000000000..9c8a03c947 --- /dev/null +++ b/src/qemu/qemu_dbus.c @@ -0,0 +1,299 @@ +/* + * 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) +{ + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + + return virDirCreate(cfg->dbusStateDir, 0770, cfg->user, cfg->group, + VIR_DIR_CREATE_ALLOW_EXIST); +} + + +static char * +qemuDBusCreatePidFilename(const char *stateDir, + const char *shortName) +{ + g_autofree char *name = g_strdup_printf("%s-dbus", shortName); + + return virPidFileBuildPath(stateDir, 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"); +} + + +char * +qemuDBusGetAddress(virQEMUDriverPtr driver, + virDomainObjPtr vm) +{ + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + g_autofree char *shortName = virDomainDefGetShortName(vm->def); + g_autofree char *path = qemuDBusCreateSocketPath(cfg, shortName); + + return g_strdup_printf("unix:path=%s", path); +} + + +static int +qemuDBusGetPid(const char *binPath, + const char *stateDir, + const char *shortName, + pid_t *pid) +{ + g_autofree char *pidfile = qemuDBusCreatePidFilename(stateDir, shortName); + + return virPidFileReadPathIfAlive(pidfile, pid, binPath); +} + + +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"); + 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"); + 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) +{ + qemuDomainObjPrivatePtr priv = vm->privateData; + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + g_autofree char *shortName = NULL; + g_autofree char *pidfile = NULL; + g_autofree char *configfile = NULL; + virErrorPtr orig_err; + int rc; + pid_t pid; + + shortName = virDomainDefGetShortName(vm->def); + pidfile = qemuDBusCreatePidFilename(cfg->dbusStateDir, shortName); + configfile = qemuDBusCreateFilename(cfg->dbusStateDir, shortName, ".conf"); + + rc = qemuDBusGetPid(cfg->dbusDaemonName, cfg->dbusStateDir, shortName, &pid); + if (rc == 0 && pid != (pid_t)-1) { + char ebuf[1024]; + + VIR_DEBUG("Killing dbus-daemon process %lld", (long long)pid); + if (virProcessKill(pid, SIGTERM) < 0 && errno != ESRCH) + VIR_ERROR(_("Failed to kill process %lld: %s"), + (long long)pid, + virStrerror(errno, ebuf, sizeof(ebuf))); + } + + virErrorPreserveLast(&orig_err); + if (virPidFileForceCleanupPath(pidfile) < 0) { + VIR_WARN("Unable to kill dbus-daemon process"); + } else { + if (unlink(pidfile) < 0 && + errno != ENOENT) { + virReportSystemError(errno, + _("Unable to remove stale pidfile %s"), + pidfile); + } + } + if (unlink(configfile) < 0 && + errno != ENOENT) { + virReportSystemError(errno, + _("Unable to remove stale configfile %s"), + pidfile); + } + virErrorRestore(&orig_err); + + priv->dbusDaemonRunning = false; +} + + +int +qemuDBusStart(virQEMUDriverPtr driver, + virDomainObjPtr vm) +{ + qemuDomainObjPrivatePtr priv = vm->privateData; + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + 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 */ + int errfd = -1; + int cmdret = 0; + int exitstatus = 0; + + if (priv->dbusDaemonRunning) + return 0; + + /* for cleanup */ + qemuDBusStop(driver, vm); + + cmd = virCommandNew(cfg->dbusDaemonName); + shortName = virDomainDefGetShortName(vm->def); + pidfile = qemuDBusCreatePidFilename(cfg->dbusStateDir, shortName); + configfile = qemuDBusCreateFilename(cfg->dbusStateDir, shortName, ".conf"); + 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) + return -1; + + virCommandClearCaps(cmd); + virCommandSetPidFile(cmd, pidfile); + virCommandSetErrorFD(cmd, &errfd); + virCommandDaemonize(cmd); + virCommandAddArgFormat(cmd, "--config-file=%s", configfile); + + if (qemuExtDeviceLogCommand(driver, vm, cmd, "DBus") < 0) + return -1; + + if (qemuSecurityCommandRun(driver, vm, cmd, -1, -1, + &exitstatus, &cmdret) < 0) + return -1; + + if (cmdret < 0 || exitstatus != 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Could not start dbus-daemon. exitstatus: %d"), exitstatus); + return -1; + } + + if (virTimeBackOffStart(&timebackoff, 1, timeout) < 0) + return -1; + while (virTimeBackOffWait(&timebackoff)) { + pid_t pid; + + if (qemuDBusGetPid(cfg->dbusDaemonName, cfg->dbusStateDir, shortName, &pid) < 0) + continue; + + if (pid == (pid_t)-1) + break; + + if (virFileExists(sockpath)) + break; + } + + if (!virFileExists(sockpath)) { + char errbuf[1024] = { 0 }; + + if (saferead(errfd, errbuf, sizeof(errbuf) - 1) < 0) { + virReportSystemError(errno, "%s", _("dbus-daemon died unexpectedly")); + } else { + virReportError(VIR_ERR_OPERATION_FAILED, + _("dbus-daemon died and reported: %s"), errbuf); + } + + return -1; + } + + if (qemuSecurityDomainSetPathLabel(driver, vm, sockpath, false) < 0) + return -1; + + priv->dbusDaemonRunning = true; + + return 0; +} + + +int +qemuDBusSetupCgroup(virQEMUDriverPtr driver, + virDomainDefPtr def, + virCgroupPtr cgroup) +{ + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + g_autofree char *shortName = virDomainDefGetShortName(def); + pid_t pid; + int rc; + + rc = qemuDBusGetPid(cfg->dbusDaemonName, cfg->dbusStateDir, shortName, &pid); + if (rc < 0 || (rc == 0 && pid == (pid_t)-1)) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("Could not get process id of dbus-daemon")); + return -1; + } + + if (virCgroupAddProcess(cgroup, pid) < 0) + return -1; + + return 0; +} diff --git a/src/qemu/qemu_dbus.h b/src/qemu/qemu_dbus.h new file mode 100644 index 0000000000..8728824bd7 --- /dev/null +++ b/src/qemu/qemu_dbus.h @@ -0,0 +1,40 @@ +/* + * 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 qemuDBusConnect(virQEMUDriverPtr driver, + virDomainObjPtr vm); + +int qemuDBusStart(virQEMUDriverPtr driver, + virDomainObjPtr vm); + +void qemuDBusStop(virQEMUDriverPtr driver, + virDomainObjPtr vm); + +int qemuDBusSetupCgroup(virQEMUDriverPtr driver, + virDomainDefPtr def, + virCgroupPtr cgroup); diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index ecd087a5cb..7722a53c62 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -2264,6 +2264,8 @@ qemuDomainObjPrivateDataClear(qemuDomainObjPrivatePtr priv) /* reset node name allocator */ qemuDomainStorageIdReset(priv); + + priv->dbusDaemonRunning = false; } diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index b2041ccea7..02c792ea2a 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -40,6 +40,7 @@ #include "logging/log_manager.h" #include "virdomainmomentobjlist.h" #include "virenum.h" +#include "virdbus.h" #define QEMU_DOMAIN_FORMAT_LIVE_FLAGS \ (VIR_DOMAIN_XML_SECURE) @@ -417,6 +418,8 @@ struct _qemuDomainObjPrivate { /* running backup job */ virDomainBackupDefPtr backup; + + bool dbusDaemonRunning; }; #define QEMU_DOMAIN_PRIVATE(vm) \ diff --git a/tests/Makefile.am b/tests/Makefile.am index f957c7d1ba..8ed5afbb9b 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -45,6 +45,7 @@ AM_CFLAGS = \ $(YAJL_CFLAGS) \ $(COVERAGE_CFLAGS) \ $(XDR_CFLAGS) \ + $(DBUS_CFLAGS) \ $(WARN_CFLAGS) AM_LDFLAGS = \ -- 2.25.0.rc2.1.g09a9a1a997