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Run QEMU guests as an unprivileged user

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* configure.in: Add --with-qemu-user and --with-qemu-group args
* libvirt.spec.in: use 'qemu' for user/group for Fedora >= 12
* qemud/libvirtd_qemu.arg, qemud/test_libvirtd_qemu.aug,
  src/qemu.conf: Add 'user' and 'group' args for configuration
* src/Makefile.am: Create %localstatedir/cache/libvirt/qemu
* src/qemu_conf.c, src/qemu_conf.h: Load user/group from config
* src/qemu_driver.c: Change user ID/group ID when launching QEMU
  guests. Change user/group ownership on disks/usb/pci devs.
  Put memory dumps in %localstatedir/cache/libvirt/qemu
* src/util.c, src/util.h: Add convenient APIs for converting
  username/groupname to user ID / group ID
This commit is contained in:
Daniel P. Berrange 2009-07-15 22:25:01 +01:00
parent d4ad29be2a
commit 0714b2ba4c
12 changed files with 417 additions and 10 deletions
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17
configure.in
View File

@ -1437,6 +1437,19 @@ AM_CONDITIONAL([WITH_NODE_DEVICES], [test "$with_nodedev" = "yes"])
AM_CONDITIONAL([WITH_LINUX], [test `uname -s` = "Linux"])
AC_ARG_WITH([qemu-user],
[ --with-qemu-user username to run QEMU system instance as],
[QEMU_USER=${withval}],
[QEMU_USER=root])
AC_ARG_WITH([qemu-group],
[ --with-qemu-group groupname to run QEMU system instance as],
[QEMU_GROUP=${withval}],
[QEMU_GROUP=root])
AC_DEFINE_UNQUOTED([QEMU_USER], ["$QEMU_USER"], [QEMU user account])
AC_DEFINE_UNQUOTED([QEMU_GROUP], ["$QEMU_GROUP"], [QEMU group account])
# Only COPYING.LIB is under version control, yet COPYING
# is included as part of the distribution tarball.
# Copy one to the other, but only if this is a srcdir-build.
@ -1578,3 +1591,7 @@ AC_MSG_NOTICE([ Debug: $enable_debug])
AC_MSG_NOTICE([ Warnings: $enable_compile_warnings])
AC_MSG_NOTICE([ Readline: $lv_use_readline])
AC_MSG_NOTICE([])
AC_MSG_NOTICE([Privileges])
AC_MSG_NOTICE([])
AC_MSG_NOTICE([ QEMU: $QEMU_USER:$QEMU_GROUP])
AC_MSG_NOTICE([])

15
libvirt.spec.in
View File

@ -46,6 +46,14 @@
%define with_capng 0%{!?_without_capng:1}
%endif
%if 0%{?fedora} >= 12
%define qemu_user qemu
%define qemu_group qemu
%else
%define qemu_user root
%define qemu_group root
%endif
#
# If building on RHEL switch on the specific support
#
@ -309,6 +317,8 @@ of recent versions of Linux (and other OSes).
%{?_without_storage_iscsi} \
%{?_without_storage_disk} \
%{?_without_numactl} \
--with-qemu-user=%{qemu_user} \
--with-qemu-group=%{qemu_group} \
--with-init-script=redhat \
--with-remote-pid-file=%{_localstatedir}/run/libvirtd.pid
make %{?_smp_mflags}
@ -445,8 +455,9 @@ fi
%dir %attr(0700, root, root) %{_localstatedir}/cache/libvirt/
%if %{with_qemu}
%dir %{_localstatedir}/run/libvirt/qemu/
%dir %attr(0700, root, root) %{_localstatedir}/lib/libvirt/qemu/
%dir %attr(0700, %{qemu_user}, %{qemu_group}) %{_localstatedir}/run/libvirt/qemu/
%dir %attr(0700, %{qemu_user}, %{qemu_group}) %{_localstatedir}/lib/libvirt/qemu/
%dir %attr(0700, %{qemu_user}, %{qemu_group}) %{_localstatedir}/cache/libvirt/qemu/
%endif
%if %{with_lxc}
%dir %{_localstatedir}/run/libvirt/lxc/

2
qemud/libvirtd_qemu.aug
View File

@ -29,6 +29,8 @@ module Libvirtd_qemu =
| str_entry "vnc_password"
| bool_entry "vnc_sasl"
| str_entry "vnc_sasl_dir"
| str_entry "user"
| str_entry "group"
(* Each enty in the config is one of the following three ... *)
let entry = vnc_entry

8
qemud/test_libvirtd_qemu.aug
View File

@ -79,6 +79,10 @@ vnc_sasl = 1
# point to the directory, and create a qemu.conf in that location
#
vnc_sasl_dir = \"/some/directory/sasl2\"
user = \"root\"
group = \"root\"
"
test Libvirtd_qemu.lns get conf =
@ -161,3 +165,7 @@ vnc_sasl_dir = \"/some/directory/sasl2\"
{ "#comment" = "point to the directory, and create a qemu.conf in that location" }
{ "#comment" = "" }
{ "vnc_sasl_dir" = "/some/directory/sasl2" }
{ "#comment" = "" }
{ "user"= "root" }
{ "#comment" = "" }
{ "group" = "root" }

1
src/Makefile.am
View File

@ -684,6 +684,7 @@ install-exec-local:
if WITH_QEMU
$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/qemu"
$(MKDIR_P) "$(DESTDIR)$(localstatedir)/run/libvirt/qemu"
$(MKDIR_P) "$(DESTDIR)$(localstatedir)/cache/libvirt/qemu"
endif
if WITH_LXC
$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/lxc"

2
src/libvirt_private.syms
View File

@ -378,6 +378,8 @@ virRun;
virSkipSpaces;
virKillProcess;
virGetUserDirectory;
virGetUserID;
virGetGroupID;
# uuid.h

7
src/qemu.conf
View File

@ -88,3 +88,10 @@
# to 'none' instead
#
# security_driver = "selinux"
# The user ID for QEMU processes run by the system instance
#user = "root"
# The group ID for QEMU processes run by the system instance
#group = "root"

32
src/qemu_conf.c
View File

@ -92,6 +92,8 @@ int qemudLoadDriverConfig(struct qemud_driver *driver,
const char *filename) {
virConfPtr conf;
virConfValuePtr p;
char *user;
char *group;
/* Setup 2 critical defaults */
if (!(driver->vncListen = strdup("127.0.0.1"))) {
@ -186,6 +188,36 @@ int qemudLoadDriverConfig(struct qemud_driver *driver,
}
}
p = virConfGetValue (conf, "user");
CHECK_TYPE ("user", VIR_CONF_STRING);
if (!(user = strdup(p && p->str ? p->str : QEMU_USER))) {
virReportOOMError(NULL);
virConfFree(conf);
return -1;
}
if (virGetUserID(NULL, user, &driver->user) < 0) {
VIR_FREE(user);
virConfFree(conf);
return -1;
}
VIR_FREE(user);
p = virConfGetValue (conf, "group");
CHECK_TYPE ("group", VIR_CONF_STRING);
if (!(group = strdup(p && p->str ? p->str : QEMU_GROUP))) {
virReportOOMError(NULL);
virConfFree(conf);
return -1;
}
if (virGetGroupID(NULL, group, &driver->group) < 0) {
VIR_FREE(group);
virConfFree(conf);
return -1;
}
VIR_FREE(group);
virConfFree (conf);
return 0;
}

3
src/qemu_conf.h
View File

@ -66,6 +66,9 @@ struct qemud_driver {
int privileged;
uid_t user;
gid_t group;
unsigned int qemuVersion;
int nextvmid;

259
src/qemu_driver.c
View File

@ -71,12 +71,11 @@
#define VIR_FROM_THIS VIR_FROM_QEMU
/* For storing short-lived temporary files. */
#define TEMPDIR LOCAL_STATE_DIR "/cache/libvirt"
#define TEMPDIR LOCAL_STATE_DIR "/cache/libvirt/qemu"
#define QEMU_CMD_PROMPT "\n(qemu) "
#define QEMU_PASSWD_PROMPT "Password: "
static int qemudShutdown(void);
static void qemuDriverLock(struct qemud_driver *driver)
@ -1367,6 +1366,205 @@ static int qemudDomainSetSecurityLabel(virConnectPtr conn, struct qemud_driver *
return 0;
}
#ifdef __linux__
static int qemuDomainSetHostdevUSBOwnership(virConnectPtr conn,
virDomainHostdevDefPtr def,
uid_t uid, gid_t gid)
{
char *usbpath = NULL;
/* XXX what todo for USB devs assigned based on product/vendor ? Doom :-( */
if (!def->source.subsys.u.usb.bus ||
!def->source.subsys.u.usb.device)
return 0;
if (virAsprintf(&usbpath, "/dev/bus/usb/%03d/%03d",
def->source.subsys.u.usb.bus,
def->source.subsys.u.usb.device) < 0) {
virReportOOMError(conn);
return -1;
}
VIR_DEBUG("Setting ownership on %s to %d:%d", usbpath, uid, gid);
if (chown(usbpath, uid, gid) < 0) {
virReportSystemError(conn, errno, _("cannot set ownership on %s"), usbpath);
VIR_FREE(usbpath);
return -1;
}
VIR_FREE(usbpath);
return 0;
}
static int qemuDomainSetHostdevPCIOwnership(virConnectPtr conn,
virDomainHostdevDefPtr def,
uid_t uid, gid_t gid)
{
char *pcidir = NULL;
char *file = NULL;
DIR *dir = NULL;
int ret = -1;
struct dirent *ent;
if (virAsprintf(&pcidir, "/sys/bus/pci/devices/%04x:%02x:%02x.%x",
def->source.subsys.u.pci.domain,
def->source.subsys.u.pci.bus,
def->source.subsys.u.pci.slot,
def->source.subsys.u.pci.function) < 0) {
virReportOOMError(conn);
goto cleanup;
}
if (!(dir = opendir(pcidir))) {
virReportSystemError(conn, errno,
_("cannot open %s"), pcidir);
goto cleanup;
}
while ((ent = readdir(dir)) != NULL) {
/* QEMU device assignment requires:
* $PCIDIR/config, $PCIDIR/resource, $PCIDIR/resourceNNN, $PCIDIR/rom
*/
if (STREQ(ent->d_name, "config") ||
STRPREFIX(ent->d_name, "resource") ||
STREQ(ent->d_name, "rom")) {
if (virAsprintf(&file, "%s/%s", pcidir, ent->d_name) < 0) {
virReportOOMError(conn);
goto cleanup;
}
VIR_DEBUG("Setting ownership on %s to %d:%d", file, uid, gid);
if (chown(file, uid, gid) < 0) {
virReportSystemError(conn, errno, _("cannot set ownership on %s"), file);
goto cleanup;
}
VIR_FREE(file);
}
}
ret = 0;
cleanup:
if (dir)
closedir(dir);
VIR_FREE(file);
VIR_FREE(pcidir);
return ret;
}
#endif
static int qemuDomainSetHostdevOwnership(virConnectPtr conn,
virDomainHostdevDefPtr def,
uid_t uid, gid_t gid)
{
if (def->mode != VIR_DOMAIN_HOSTDEV_MODE_SUBSYS)
return 0;
#ifdef __linux__
switch (def->source.subsys.type) {
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB:
return qemuDomainSetHostdevUSBOwnership(conn, def, uid, gid);
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI:
return qemuDomainSetHostdevPCIOwnership(conn, def, uid, gid);
}
return 0;
#else
qemudReportError(conn, NULL, NULL, "%s",
_("unable to set host device ownership on this platform"));
return -1;
#endif
}
static int qemuDomainSetDiskOwnership(virConnectPtr conn,
virDomainDiskDefPtr def,
uid_t uid, gid_t gid)
{
if (!def->src)
return 0;
VIR_DEBUG("Setting ownership on %s to %d:%d", def->src, uid, gid);
if (chown(def->src, uid, gid) < 0) {
virReportSystemError(conn, errno, _("cannot set ownership on %s"),
def->src);
return -1;
}
return 0;
}
static int qemuDomainSetDeviceOwnership(virConnectPtr conn,
struct qemud_driver *driver,
virDomainDeviceDefPtr def,
int restore)
{
uid_t uid;
gid_t gid;
if (!driver->privileged)
return 0;
/* short circuit case of root:root */
if (!driver->user && !driver->group)
return 0;
uid = restore ? 0 : driver->user;
gid = restore ? 0 : driver->group;
switch (def->type) {
case VIR_DOMAIN_DEVICE_DISK:
if (restore &&
(def->data.disk->readonly || def->data.disk->shared))
return 0;
return qemuDomainSetDiskOwnership(conn, def->data.disk, uid, gid);
case VIR_DOMAIN_DEVICE_HOSTDEV:
return qemuDomainSetHostdevOwnership(conn, def->data.hostdev, uid, gid);
}
return 0;
}
static int qemuDomainSetAllDeviceOwnership(virConnectPtr conn,
struct qemud_driver *driver,
virDomainDefPtr def,
int restore)
{
int i;
uid_t uid;
gid_t gid;
if (!driver->privileged)
return 0;
/* short circuit case of root:root */
if (!driver->user && !driver->group)
return 0;
uid = restore ? 0 : driver->user;
gid = restore ? 0 : driver->group;
for (i = 0 ; i < def->ndisks ; i++) {
if (restore &&
(def->disks[i]->readonly || def->disks[i]->shared))
continue;
if (qemuDomainSetDiskOwnership(conn, def->disks[i], uid, gid) < 0)
return -1;
}
for (i = 0 ; i < def->nhostdevs ; i++) {
if (qemuDomainSetHostdevOwnership(conn, def->hostdevs[i], uid, gid) < 0)
return -1;
}
return 0;
}
static virDomainPtr qemudDomainLookupByName(virConnectPtr conn,
const char *name);
@ -1377,14 +1575,39 @@ struct gemudHookData {
};
static int qemudSecurityHook(void *data) {
struct gemudHookData *h = (struct gemudHookData *) data;
struct gemudHookData *h = (struct gemudHookData *) data;
if (qemudDomainSetSecurityLabel(h->conn, h->driver, h->vm) < 0) {
qemudReportError(h->conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
_("Failed to set security label"));
if (qemudDomainSetSecurityLabel(h->conn, h->driver, h->vm) < 0) {
qemudReportError(h->conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
_("Failed to set security label"));
return -1;
}
if (h->driver->privileged) {
DEBUG("Dropping privileges of VM to %d:%d", h->driver->user, h->driver->group);
if (qemuDomainSetAllDeviceOwnership(h->conn, h->driver, h->vm->def, 0) < 0)
return -1;
if (h->driver->group) {
if (setregid(h->driver->group, h->driver->group) < 0) {
virReportSystemError(NULL, errno,
_("cannot change to '%d' group"),
h->driver->group);
return -1;
}
}
return 0;
if (h->driver->user) {
if (setreuid(h->driver->user, h->driver->user) < 0) {
virReportSystemError(NULL, errno,
_("cannot change to '%d' user"),
h->driver->user);
return -1;
}
}
}
return 0;
}
static int
@ -1662,6 +1885,10 @@ static void qemudShutdownVMDaemon(virConnectPtr conn ATTRIBUTE_UNUSED,
VIR_FREE(vm->def->seclabel.imagelabel);
}
if (qemuDomainSetAllDeviceOwnership(conn, driver, vm->def, 1) < 0)
VIR_WARN("Failed to restore all device ownership for %s",
vm->def->name);
if (qemudRemoveDomainStatus(conn, driver, vm) < 0) {
VIR_WARN(_("Failed to remove domain status for %s"),
vm->def->name);
@ -4329,12 +4556,20 @@ static int qemudDomainAttachDevice(virDomainPtr dom,
case VIR_DOMAIN_DISK_DEVICE_FLOPPY:
if (driver->securityDriver)
driver->securityDriver->domainSetSecurityImageLabel(dom->conn, vm, dev->data.disk);
if (qemuDomainSetDeviceOwnership(dom->conn, driver, dev, 0) < 0)
goto cleanup;
ret = qemudDomainChangeEjectableMedia(dom->conn, vm, dev);
break;
case VIR_DOMAIN_DISK_DEVICE_DISK:
if (driver->securityDriver)
driver->securityDriver->domainSetSecurityImageLabel(dom->conn, vm, dev->data.disk);
if (qemuDomainSetDeviceOwnership(dom->conn, driver, dev, 0) < 0)
goto cleanup;
if (dev->data.disk->bus == VIR_DOMAIN_DISK_BUS_USB) {
ret = qemudDomainAttachUsbMassstorageDevice(dom->conn, vm, dev);
} else if (dev->data.disk->bus == VIR_DOMAIN_DISK_BUS_SCSI ||
@ -4357,6 +4592,9 @@ static int qemudDomainAttachDevice(virDomainPtr dom,
} else if (dev->type == VIR_DOMAIN_DEVICE_HOSTDEV &&
dev->data.hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
dev->data.hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB) {
if (qemuDomainSetDeviceOwnership(dom->conn, driver, dev, 0) < 0)
goto cleanup;
ret = qemudDomainAttachHostDevice(dom->conn, vm, dev);
} else {
qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT,
@ -4369,8 +4607,11 @@ static int qemudDomainAttachDevice(virDomainPtr dom,
ret = -1;
cleanup:
if (ret < 0)
if (ret < 0) {
if (qemuDomainSetDeviceOwnership(dom->conn, driver, dev, 1) < 0)
VIR_WARN0("Fail to restore disk device ownership");
virDomainDeviceDefFree(dev);
}
if (vm)
virDomainObjUnlock(vm);
qemuDriverUnlock(driver);
@ -4498,6 +4739,8 @@ static int qemudDomainDetachDevice(virDomainPtr dom,
ret = qemudDomainDetachPciDiskDevice(dom->conn, vm, dev);
if (driver->securityDriver)
driver->securityDriver->domainRestoreSecurityImageLabel(dom->conn, dev->data.disk);
if (qemuDomainSetDeviceOwnership(dom->conn, driver, dev, 1) < 0)
VIR_WARN0("Fail to restore disk device ownership");
}
else
qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT,

75
src/util.c
View File

@ -55,6 +55,7 @@
#include <netdb.h>
#ifdef HAVE_GETPWUID_R
#include <pwd.h>
#include <grp.h>
#endif
#if HAVE_CAPNG
#include <cap-ng.h>
@ -1862,4 +1863,78 @@ char *virGetUserDirectory(virConnectPtr conn,
return ret;
}
int virGetUserID(virConnectPtr conn,
const char *name,
uid_t *uid)
{
char *strbuf;
struct passwd pwbuf;
struct passwd *pw = NULL;
size_t strbuflen = sysconf(_SC_GETPW_R_SIZE_MAX);
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError(conn);
return -1;
}
/*
* From the manpage (terrifying but true):
*
* ERRORS
* 0 or ENOENT or ESRCH or EBADF or EPERM or ...
* The given name or uid was not found.
*/
if (getpwnam_r(name, &pwbuf, strbuf, strbuflen, &pw) != 0 || pw == NULL) {
virReportSystemError(conn, errno,
_("Failed to find user record for name '%s'"),
name);
VIR_FREE(strbuf);
return -1;
}
*uid = pw->pw_uid;
VIR_FREE(strbuf);
return 0;
}
int virGetGroupID(virConnectPtr conn,
const char *name,
gid_t *gid)
{
char *strbuf;
struct group grbuf;
struct group *gr = NULL;
size_t strbuflen = sysconf(_SC_GETGR_R_SIZE_MAX);
if (VIR_ALLOC_N(strbuf, strbuflen) < 0) {
virReportOOMError(conn);
return -1;
}
/*
* From the manpage (terrifying but true):
*
* ERRORS
* 0 or ENOENT or ESRCH or EBADF or EPERM or ...
* The given name or uid was not found.
*/
if (getgrnam_r(name, &grbuf, strbuf, strbuflen, &gr) != 0 || gr == NULL) {
virReportSystemError(conn, errno,
_("Failed to find group record for name '%s'"),
name);
VIR_FREE(strbuf);
return -1;
}
*gid = gr->gr_gid;
VIR_FREE(strbuf);
return 0;
}
#endif

6
src/util.h
View File

@ -217,6 +217,12 @@ int virKillProcess(pid_t pid, int sig);
#ifdef HAVE_GETPWUID_R
char *virGetUserDirectory(virConnectPtr conn,
uid_t uid);
int virGetUserID(virConnectPtr conn,
const char *name,
uid_t *uid);
int virGetGroupID(virConnectPtr conn,
const char *name,
gid_t *gid);
#endif
int virRandomInitialize(unsigned int seed);