Attaching a newly created vhostuser port to a VM fails due to an
apparmor denial
internal error: unable to execute QEMU command 'chardev-add': Failed
to bind socket to /run/openvswitch/vhu838c4d29-c9: Permission denied
In the case of a net device type VIR_DOMAIN_NET_TYPE_VHOSTUSER, the
underlying chardev is not labeled in qemuDomainAttachNetDevice prior
to calling qemuMonitorAttachCharDev.
A simple fix would be to call qemuSecuritySetChardevLabel using the
embedded virDomainChrSourceDef in the virDomainNetDef vhostuser data,
but this incurs the risk of incorrectly restoring the label. E.g.
consider the DAC driver behavior with a vhostuser net device, which
uses a socket for the chardev backend. The DAC driver uses XATTRS to
store original labelling information, but XATTRS are not compatible
with sockets. Without the original labelling information, the socket
labels will be restored with root ownership, preventing other
less-privileged processes from connecting to the socket.
This patch avoids overloading chardev labelling with vhostuser net
devices by introducing virSecurityManager{Set,Restore}NetdevLabel,
which is currently only implemented for the apparmor driver. The
new APIs are then used to set and restore labels for the vhostuser
net devices.
Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
V2 of:
https://listman.redhat.com/archives/libvir-list/2021-August/msg00373.html
Changes since V1:
Introduce and use new APIs for labeling net devices
Don't perform labelling while executing monitor commands
Restore labels if hotplug fails
src/libvirt_private.syms | 2 ++
src/qemu/qemu_hotplug.c | 13 +++++++
src/qemu/qemu_security.c | 59 ++++++++++++++++++++++++++++++
src/qemu/qemu_security.h | 8 +++++
src/security/security_apparmor.c | 61 ++++++++++++++++++++++++++++++++
src/security/security_driver.h | 9 +++++
src/security/security_manager.c | 38 ++++++++++++++++++++
src/security/security_manager.h | 8 +++++
src/security/security_stack.c | 52 +++++++++++++++++++++++++++
9 files changed, 250 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index fcb02c21b1..9d3e0421c0 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1687,6 +1687,7 @@ virSecurityManagerRestoreHostdevLabel;
virSecurityManagerRestoreImageLabel;
virSecurityManagerRestoreInputLabel;
virSecurityManagerRestoreMemoryLabel;
+virSecurityManagerRestoreNetdevLabel;
virSecurityManagerRestoreSavedStateLabel;
virSecurityManagerRestoreTPMLabels;
virSecurityManagerSetAllLabel;
@@ -1698,6 +1699,7 @@ virSecurityManagerSetImageFDLabel;
virSecurityManagerSetImageLabel;
virSecurityManagerSetInputLabel;
virSecurityManagerSetMemoryLabel;
+virSecurityManagerSetNetdevLabel;
virSecurityManagerSetProcessLabel;
virSecurityManagerSetSavedStateLabel;
virSecurityManagerSetSocketLabel;
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index c3c49fe080..77dbf69845 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1203,6 +1203,7 @@ qemuDomainAttachNetDevice(virQEMUDriver *driver,
g_autofree char *netdev_name = NULL;
g_autoptr(virConnect) conn = NULL;
virErrorPtr save_err = NULL;
+ bool teardownlabel = false;
/* If appropriate, grab a physical device from the configured
* network's pool of devices, or resolve bridge device name
@@ -1343,6 +1344,9 @@ qemuDomainAttachNetDevice(virQEMUDriver *driver,
&net->ifname) < 0)
goto cleanup;
+ if (qemuSecuritySetNetdevLabel(driver, vm, net) < 0)
+ goto cleanup;
+ teardownlabel = true;
break;
case VIR_DOMAIN_NET_TYPE_USER:
@@ -1559,6 +1563,10 @@ qemuDomainAttachNetDevice(virQEMUDriver *driver,
qemuDomainNetDeviceVportRemove(net);
}
+ if (teardownlabel &&
+ qemuSecurityRestoreNetdevLabel(driver, vm, net) < 0)
+ VIR_WARN("Unable to restore network device labelling on hotplug fail");
+
/* we had potentially pre-added the device to the domain
* device lists, if so we need to remove it (from def->nets
* and/or def->hostdevs) on failure
@@ -4763,6 +4771,11 @@ qemuDomainRemoveNetDevice(virQEMUDriver *driver,
cfg->stateDir));
}
+ if (actualType == VIR_DOMAIN_NET_TYPE_VHOSTUSER) {
+ if (qemuSecurityRestoreNetdevLabel(driver, vm, net) < 0)
+ VIR_WARN("Unable to restore security label on vhostuser char device");
+ }
+
qemuDomainNetDeviceVportRemove(net);
if (net->type == VIR_DOMAIN_NET_TYPE_NETWORK) {
diff --git a/src/qemu/qemu_security.c b/src/qemu/qemu_security.c
index e582a66071..19d957dd4b 100644
--- a/src/qemu/qemu_security.c
+++ b/src/qemu/qemu_security.c
@@ -439,6 +439,65 @@ qemuSecurityRestoreChardevLabel(virQEMUDriver *driver,
return ret;
}
+int
+qemuSecuritySetNetdevLabel(virQEMUDriver *driver,
+ virDomainObj *vm,
+ virDomainNetDef *net)
+{
+ int ret = -1;
+ qemuDomainObjPrivate *priv = vm->privateData;
+ pid_t pid = -1;
+
+ if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT))
+ pid = vm->pid;
+
+ if (virSecurityManagerTransactionStart(driver->securityManager) < 0)
+ goto cleanup;
+
+ if (virSecurityManagerSetNetdevLabel(driver->securityManager,
+ vm->def, net) < 0)
+ goto cleanup;
+
+ if (virSecurityManagerTransactionCommit(driver->securityManager,
+ pid, priv->rememberOwner) < 0)
+ goto cleanup;
+
+ ret = 0;
+ cleanup:
+ virSecurityManagerTransactionAbort(driver->securityManager);
+ return ret;
+}
+
+
+int
+qemuSecurityRestoreNetdevLabel(virQEMUDriver *driver,
+ virDomainObj *vm,
+ virDomainNetDef *net)
+{
+ int ret = -1;
+ qemuDomainObjPrivate *priv = vm->privateData;
+ pid_t pid = -1;
+
+ if (qemuDomainNamespaceEnabled(vm, QEMU_DOMAIN_NS_MOUNT))
+ pid = vm->pid;
+
+ if (virSecurityManagerTransactionStart(driver->securityManager) < 0)
+ goto cleanup;
+
+ if (virSecurityManagerRestoreNetdevLabel(driver->securityManager,
+ vm->def, net) < 0)
+ goto cleanup;
+
+ if (virSecurityManagerTransactionCommit(driver->securityManager,
+ pid, priv->rememberOwner) < 0)
+ goto cleanup;
+
+ ret = 0;
+ cleanup:
+ virSecurityManagerTransactionAbort(driver->securityManager);
+ return ret;
+}
+
/*
* qemuSecurityStartVhostUserGPU:
diff --git a/src/qemu/qemu_security.h b/src/qemu/qemu_security.h
index 4c3d81e4b5..8b26ea3f99 100644
--- a/src/qemu/qemu_security.h
+++ b/src/qemu/qemu_security.h
@@ -79,6 +79,14 @@ int qemuSecurityRestoreChardevLabel(virQEMUDriver *driver,
virDomainObj *vm,
virDomainChrDef *chr);
+int qemuSecuritySetNetdevLabel(virQEMUDriver *driver,
+ virDomainObj *vm,
+ virDomainNetDef *net);
+
+int qemuSecurityRestoreNetdevLabel(virQEMUDriver *driver,
+ virDomainObj *vm,
+ virDomainNetDef *net);
+
int qemuSecurityStartVhostUserGPU(virQEMUDriver *driver,
virDomainObj *vm,
virCommand *cmd,
diff --git a/src/security/security_apparmor.c b/src/security/security_apparmor.c
index 84363015dc..d942ea5005 100644
--- a/src/security/security_apparmor.c
+++ b/src/security/security_apparmor.c
@@ -1053,6 +1053,64 @@ AppArmorRestoreChardevLabel(virSecurityManager *mgr,
return reload_profile(mgr, def, NULL, false);
}
+static int
+AppArmorSetNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net)
+{
+ int ret = -1;
+ virSecurityLabelDef *secdef;
+ virDomainChrSourceDef *dev_source;
+ virDomainNetType actualType;
+
+ secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_APPARMOR_NAME);
+ if (!secdef)
+ return 0;
+
+ actualType = virDomainNetGetActualType(net);
+ if (actualType != VIR_DOMAIN_NET_TYPE_VHOSTUSER)
+ return 0;
+
+ dev_source = net->data.vhostuser;
+ switch ((virDomainChrType)dev_source->type) {
+ case VIR_DOMAIN_CHR_TYPE_UNIX:
+ ret = reload_profile(mgr, def, dev_source->data.file.path, true);
+ break;
+
+ case VIR_DOMAIN_CHR_TYPE_DEV:
+ case VIR_DOMAIN_CHR_TYPE_FILE:
+ case VIR_DOMAIN_CHR_TYPE_PTY:
+ case VIR_DOMAIN_CHR_TYPE_PIPE:
+ case VIR_DOMAIN_CHR_TYPE_SPICEPORT:
+ case VIR_DOMAIN_CHR_TYPE_NULL:
+ case VIR_DOMAIN_CHR_TYPE_VC:
+ case VIR_DOMAIN_CHR_TYPE_STDIO:
+ case VIR_DOMAIN_CHR_TYPE_UDP:
+ case VIR_DOMAIN_CHR_TYPE_TCP:
+ case VIR_DOMAIN_CHR_TYPE_SPICEVMC:
+ case VIR_DOMAIN_CHR_TYPE_NMDM:
+ case VIR_DOMAIN_CHR_TYPE_LAST:
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+static int
+AppArmorRestoreNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net G_GNUC_UNUSED)
+{
+ virSecurityLabelDef *secdef;
+
+ secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_APPARMOR_NAME);
+ if (!secdef)
+ return 0;
+
+ return reload_profile(mgr, def, NULL, false);
+}
+
static int
AppArmorSetPathLabel(virSecurityManager *mgr,
virDomainDef *def,
@@ -1168,6 +1226,9 @@ virSecurityDriver virAppArmorSecurityDriver = {
.domainSetSecurityChardevLabel = AppArmorSetChardevLabel,
.domainRestoreSecurityChardevLabel = AppArmorRestoreChardevLabel,
+ .domainSetSecurityNetdevLabel = AppArmorSetNetdevLabel,
+ .domainRestoreSecurityNetdevLabel = AppArmorRestoreNetdevLabel,
+
.domainSetSecurityImageFDLabel = AppArmorSetFDLabel,
.domainSetSecurityTapFDLabel = AppArmorSetFDLabel,
diff --git a/src/security/security_driver.h b/src/security/security_driver.h
index 07f8def3d3..a1fc23be38 100644
--- a/src/security/security_driver.h
+++ b/src/security/security_driver.h
@@ -157,6 +157,12 @@ typedef int (*virSecurityDomainSetTPMLabels) (virSecurityManager *mgr,
virDomainDef *def);
typedef int (*virSecurityDomainRestoreTPMLabels) (virSecurityManager *mgr,
virDomainDef *def);
+typedef int (*virSecurityDomainSetNetdevLabel) (virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net);
+typedef int (*virSecurityDomainRestoreNetdevLabel) (virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net);
struct _virSecurityDriver {
@@ -224,6 +230,9 @@ struct _virSecurityDriver {
virSecurityDomainSetTPMLabels domainSetSecurityTPMLabels;
virSecurityDomainRestoreTPMLabels domainRestoreSecurityTPMLabels;
+
+ virSecurityDomainSetNetdevLabel domainSetSecurityNetdevLabel;
+ virSecurityDomainRestoreNetdevLabel domainRestoreSecurityNetdevLabel;
};
virSecurityDriver *virSecurityDriverLookup(const char *name,
diff --git a/src/security/security_manager.c b/src/security/security_manager.c
index 9906c1691d..d8a03a19cb 100644
--- a/src/security/security_manager.c
+++ b/src/security/security_manager.c
@@ -1297,6 +1297,44 @@ virSecurityManagerRestoreTPMLabels(virSecurityManager *mgr,
}
+int
+virSecurityManagerSetNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *vm,
+ virDomainNetDef *net)
+{
+ int ret;
+
+ if (mgr->drv->domainSetSecurityNetdevLabel) {
+ virObjectLock(mgr);
+ ret = mgr->drv->domainSetSecurityNetdevLabel(mgr, vm, net);
+ virObjectUnlock(mgr);
+
+ return ret;
+ }
+
+ return 0;
+}
+
+
+int
+virSecurityManagerRestoreNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *vm,
+ virDomainNetDef *net)
+{
+ int ret;
+
+ if (mgr->drv->domainRestoreSecurityNetdevLabel) {
+ virObjectLock(mgr);
+ ret = mgr->drv->domainRestoreSecurityNetdevLabel(mgr, vm, net);
+ virObjectUnlock(mgr);
+
+ return ret;
+ }
+
+ return 0;
+}
+
+
static int
cmpstringp(const void *p1, const void *p2)
{
diff --git a/src/security/security_manager.h b/src/security/security_manager.h
index 57047ccb13..59020b1475 100644
--- a/src/security/security_manager.h
+++ b/src/security/security_manager.h
@@ -220,6 +220,14 @@ int virSecurityManagerSetTPMLabels(virSecurityManager *mgr,
int virSecurityManagerRestoreTPMLabels(virSecurityManager *mgr,
virDomainDef *vm);
+int virSecurityManagerSetNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *vm,
+ virDomainNetDef *net);
+
+int virSecurityManagerRestoreNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *vm,
+ virDomainNetDef *net);
+
typedef struct _virSecurityManagerMetadataLockState virSecurityManagerMetadataLockState;
struct _virSecurityManagerMetadataLockState {
size_t nfds; /* Captures size of both @fds and @paths */
diff --git a/src/security/security_stack.c b/src/security/security_stack.c
index f7a9ed1e33..3c2239910a 100644
--- a/src/security/security_stack.c
+++ b/src/security/security_stack.c
@@ -963,6 +963,55 @@ virSecurityStackRestoreTPMLabels(virSecurityManager *mgr,
}
+static int
+virSecurityStackDomainSetNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net)
+{
+ virSecurityStackData *priv = virSecurityManagerGetPrivateData(mgr);
+ virSecurityStackItem *item = priv->itemsHead;
+
+ for (; item; item = item->next) {
+ if (virSecurityManagerSetNetdevLabel(item->securityManager, def, net) < 0)
+ goto rollback;
+ }
+
+ return 0;
+
+ rollback:
+ for (item = item->prev; item; item = item->prev) {
+ if (virSecurityManagerRestoreNetdevLabel(item->securityManager,
+ def, net) < 0) {
+ VIR_WARN("Unable to restore netdev label after failed set label "
+ "call virDriver=%s driver=%s domain=%s",
+ virSecurityManagerGetVirtDriver(mgr),
+ virSecurityManagerGetDriver(item->securityManager),
+ def->name);
+ }
+ }
+ return -1;
+}
+
+
+static int
+virSecurityStackDomainRestoreNetdevLabel(virSecurityManager *mgr,
+ virDomainDef *def,
+ virDomainNetDef *net)
+{
+ virSecurityStackData *priv = virSecurityManagerGetPrivateData(mgr);
+ virSecurityStackItem *item = priv->itemsHead;
+ int rc = 0;
+
+ for (; item; item = item->next) {
+ if (virSecurityManagerRestoreNetdevLabel(item->securityManager,
+ def, net) < 0)
+ rc = -1;
+ }
+
+ return rc;
+}
+
+
virSecurityDriver virSecurityDriverStack = {
.privateDataLen = sizeof(virSecurityStackData),
.name = "stack",
@@ -1028,4 +1077,7 @@ virSecurityDriver virSecurityDriverStack = {
.domainSetSecurityTPMLabels = virSecurityStackSetTPMLabels,
.domainRestoreSecurityTPMLabels = virSecurityStackRestoreTPMLabels,
+
+ .domainSetSecurityNetdevLabel = virSecurityStackDomainSetNetdevLabel,
+ .domainRestoreSecurityNetdevLabel = virSecurityStackDomainRestoreNetdevLabel,
};
--
2.32.0
