commit 2e8ebfe3fa17bb785d6bc26a17391dc4f34ad8b3

Author: Jim Fehlig <jfehlig@suse.com>

Date:   Tue Jul 27 18:13:36 2021 -0600

​

    qemu: Set label on vhostuser net device when hotplugging

    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@suse.com>

    Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

​

Index: libvirt-7.1.0/src/libvirt_private.syms

===================================================================

--- libvirt-7.1.0.orig/src/libvirt_private.syms

+++ libvirt-7.1.0/src/libvirt_private.syms

@@ -1657,6 +1657,7 @@ virSecurityManagerRestoreHostdevLabel;

 virSecurityManagerRestoreImageLabel;

 virSecurityManagerRestoreInputLabel;

 virSecurityManagerRestoreMemoryLabel;

+virSecurityManagerRestoreNetdevLabel;

 virSecurityManagerRestoreSavedStateLabel;

 virSecurityManagerRestoreTPMLabels;

 virSecurityManagerSetAllLabel;

@@ -1668,6 +1669,7 @@ virSecurityManagerSetImageFDLabel;

 virSecurityManagerSetImageLabel;

 virSecurityManagerSetInputLabel;

 virSecurityManagerSetMemoryLabel;

+virSecurityManagerSetNetdevLabel;

 virSecurityManagerSetProcessLabel;

 virSecurityManagerSetSavedStateLabel;

 virSecurityManagerSetSocketLabel;

Index: libvirt-7.1.0/src/qemu/qemu_hotplug.c

===================================================================

--- libvirt-7.1.0.orig/src/qemu/qemu_hotplug.c

+++ libvirt-7.1.0/src/qemu/qemu_hotplug.c

@@ -1196,6 +1196,7 @@ qemuDomainAttachNetDevice(virQEMUDriverP

     g_autofree char *netdev_name = NULL;

     g_autoptr(virConnect) conn = NULL;

     virErrorPtr save_err = NULL;

+    bool teardownlabel = false;

     /* preallocate new slot for device */

     if (VIR_REALLOC_N(vm->def->nets, vm->def->nnets + 1) < 0)

@@ -1323,6 +1324,9 @@ qemuDomainAttachNetDevice(virQEMUDriverP

                                                    &net->ifname) < 0)

             goto cleanup;

+        if (qemuSecuritySetNetdevLabel(driver, vm, net) < 0)

+            goto cleanup;

+        teardownlabel = true;

         break;

     case VIR_DOMAIN_NET_TYPE_USER:

@@ -1531,6 +1535,10 @@ qemuDomainAttachNetDevice(virQEMUDriverP

             qemuDomainNetDeviceVportRemove(net);

         }

+        if (teardownlabel &&

+            qemuSecurityRestoreNetdevLabel(driver, vm, net) < 0)

+            VIR_WARN("Unable to restore network device labelling on hotplug fail");

+

         virDomainNetRemoveHostdev(vm->def, net);

         if (net->type == VIR_DOMAIN_NET_TYPE_NETWORK) {

@@ -4732,6 +4740,11 @@ qemuDomainRemoveNetDevice(virQEMUDriverP

                          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) {

Index: libvirt-7.1.0/src/qemu/qemu_security.c

===================================================================

--- libvirt-7.1.0.orig/src/qemu/qemu_security.c

+++ libvirt-7.1.0/src/qemu/qemu_security.c

@@ -439,6 +439,65 @@ qemuSecurityRestoreChardevLabel(virQEMUD

     return ret;

 }

+int

+qemuSecuritySetNetdevLabel(virQEMUDriverPtr driver,

+                           virDomainObjPtr vm,

+                           virDomainNetDefPtr net)

+{

+    int ret = -1;

+    qemuDomainObjPrivatePtr 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(virQEMUDriverPtr driver,

+                               virDomainObjPtr vm,

+                               virDomainNetDefPtr net)

+{

+    int ret = -1;

+    qemuDomainObjPrivatePtr 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:

Index: libvirt-7.1.0/src/qemu/qemu_security.h

===================================================================

--- libvirt-7.1.0.orig/src/qemu/qemu_security.h

+++ libvirt-7.1.0/src/qemu/qemu_security.h

@@ -79,6 +79,14 @@ int qemuSecurityRestoreChardevLabel(virQ

                                     virDomainObjPtr vm,

                                     virDomainChrDefPtr chr);

+int qemuSecuritySetNetdevLabel(virQEMUDriverPtr driver,

+                               virDomainObjPtr vm,

+                               virDomainNetDefPtr net);

+

+int qemuSecurityRestoreNetdevLabel(virQEMUDriverPtr driver,

+                                   virDomainObjPtr vm,

+                                   virDomainNetDefPtr net);

+

 int qemuSecurityStartVhostUserGPU(virQEMUDriverPtr driver,

                                   virDomainObjPtr vm,

                                   virCommandPtr cmd,

Index: libvirt-7.1.0/src/security/security_apparmor.c

===================================================================

--- libvirt-7.1.0.orig/src/security/security_apparmor.c

+++ libvirt-7.1.0/src/security/security_apparmor.c

@@ -1053,6 +1053,64 @@ AppArmorRestoreChardevLabel(virSecurityM

 }

 static int

+AppArmorSetNetdevLabel(virSecurityManagerPtr mgr,

+                       virDomainDefPtr def,

+                       virDomainNetDefPtr net)

+{

+    int ret = -1;

+    virSecurityLabelDefPtr secdef;

+    virDomainChrSourceDefPtr 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(virSecurityManagerPtr mgr,

+                           virDomainDefPtr def,

+                           virDomainNetDefPtr net G_GNUC_UNUSED)

+{

+    virSecurityLabelDefPtr secdef;

+

+    secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_APPARMOR_NAME);

+    if (!secdef)

+        return 0;

+

+    return reload_profile(mgr, def, NULL, false);

+}

+

+static int

 AppArmorSetPathLabel(virSecurityManagerPtr mgr,

                            virDomainDefPtr def,

                            const char *path,

@@ -1167,6 +1225,9 @@ virSecurityDriver virAppArmorSecurityDri

     .domainSetSecurityChardevLabel      = AppArmorSetChardevLabel,

     .domainRestoreSecurityChardevLabel  = AppArmorRestoreChardevLabel,

+    .domainSetSecurityNetdevLabel       = AppArmorSetNetdevLabel,

+    .domainRestoreSecurityNetdevLabel   = AppArmorRestoreNetdevLabel,

+

     .domainSetSecurityImageFDLabel      = AppArmorSetFDLabel,

     .domainSetSecurityTapFDLabel        = AppArmorSetFDLabel,

Index: libvirt-7.1.0/src/security/security_driver.h

===================================================================

--- libvirt-7.1.0.orig/src/security/security_driver.h

+++ libvirt-7.1.0/src/security/security_driver.h

@@ -158,6 +158,12 @@ typedef int (*virSecurityDomainSetTPMLab

                                               virDomainDefPtr def);

 typedef int (*virSecurityDomainRestoreTPMLabels) (virSecurityManagerPtr mgr,

                                                   virDomainDefPtr def);

+typedef int (*virSecurityDomainSetNetdevLabel) (virSecurityManagerPtr mgr,

+                                                virDomainDefPtr def,

+                                                virDomainNetDefPtr net);

+typedef int (*virSecurityDomainRestoreNetdevLabel) (virSecurityManagerPtr mgr,

+                                                    virDomainDefPtr def,

+                                                    virDomainNetDefPtr net);

 struct _virSecurityDriver {

@@ -225,6 +231,9 @@ struct _virSecurityDriver {

     virSecurityDomainSetTPMLabels domainSetSecurityTPMLabels;

     virSecurityDomainRestoreTPMLabels domainRestoreSecurityTPMLabels;

+

+    virSecurityDomainSetNetdevLabel domainSetSecurityNetdevLabel;

+    virSecurityDomainRestoreNetdevLabel domainRestoreSecurityNetdevLabel;

 };

 virSecurityDriverPtr virSecurityDriverLookup(const char *name,

Index: libvirt-7.1.0/src/security/security_manager.c

===================================================================

--- libvirt-7.1.0.orig/src/security/security_manager.c

+++ libvirt-7.1.0/src/security/security_manager.c

@@ -1298,6 +1298,44 @@ virSecurityManagerRestoreTPMLabels(virSe

 }

+int

+virSecurityManagerSetNetdevLabel(virSecurityManagerPtr mgr,

+                                 virDomainDefPtr vm,

+                                 virDomainNetDefPtr net)

+{

+    int ret;

+

+    if (mgr->drv->domainSetSecurityNetdevLabel) {

+        virObjectLock(mgr);

+        ret = mgr->drv->domainSetSecurityNetdevLabel(mgr, vm, net);

+        virObjectUnlock(mgr);

+

+        return ret;

+    }

+

+    return 0;

+}

+

+

+int

+virSecurityManagerRestoreNetdevLabel(virSecurityManagerPtr mgr,

+                                     virDomainDefPtr vm,

+                                     virDomainNetDefPtr 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)

 {

Index: libvirt-7.1.0/src/security/security_manager.h

===================================================================

--- libvirt-7.1.0.orig/src/security/security_manager.h

+++ libvirt-7.1.0/src/security/security_manager.h

@@ -214,6 +214,14 @@ int virSecurityManagerSetTPMLabels(virSe

 int virSecurityManagerRestoreTPMLabels(virSecurityManagerPtr mgr,

                                        virDomainDefPtr vm);

+int virSecurityManagerSetNetdevLabel(virSecurityManagerPtr mgr,

+                                     virDomainDefPtr vm,

+                                     virDomainNetDefPtr net);

+

+int virSecurityManagerRestoreNetdevLabel(virSecurityManagerPtr mgr,

+                                         virDomainDefPtr vm,

+                                         virDomainNetDefPtr net);

+

 typedef struct _virSecurityManagerMetadataLockState virSecurityManagerMetadataLockState;

 typedef virSecurityManagerMetadataLockState *virSecurityManagerMetadataLockStatePtr;

 struct _virSecurityManagerMetadataLockState {

Index: libvirt-7.1.0/src/security/security_stack.c

===================================================================

--- libvirt-7.1.0.orig/src/security/security_stack.c

+++ libvirt-7.1.0/src/security/security_stack.c

@@ -964,6 +964,55 @@ virSecurityStackRestoreTPMLabels(virSecu

 }

+static int

+virSecurityStackDomainSetNetdevLabel(virSecurityManagerPtr mgr,

+                                     virDomainDefPtr def,

+                                     virDomainNetDefPtr net)

+{

+    virSecurityStackDataPtr priv = virSecurityManagerGetPrivateData(mgr);

+    virSecurityStackItemPtr 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(virSecurityManagerPtr mgr,

+                                         virDomainDefPtr def,

+                                         virDomainNetDefPtr net)

+{

+    virSecurityStackDataPtr priv = virSecurityManagerGetPrivateData(mgr);

+    virSecurityStackItemPtr 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",

@@ -1029,4 +1078,7 @@ virSecurityDriver virSecurityDriverStack

     .domainSetSecurityTPMLabels         = virSecurityStackSetTPMLabels,

     .domainRestoreSecurityTPMLabels     = virSecurityStackRestoreTPMLabels,

+

+    .domainSetSecurityNetdevLabel      = virSecurityStackDomainSetNetdevLabel,

+    .domainRestoreSecurityNetdevLabel  = virSecurityStackDomainRestoreNetdevLabel,

 };

​