Added <capabilities> in the <features> section of LXC domains configuration. This section can contain elements named after the capabilities like: <mknod state="on"/>, keep CAP_MKNOD capability <sys_chroot state="off"/> drop CAP_SYS_CHROOT capability Users can restrict or give more capabilities than the default using this mechanism. --- docs/schemas/domaincommon.rng | 207 ++++++++++++++++++++++++ src/conf/domain_conf.c | 126 ++++++++++++++- src/conf/domain_conf.h | 56 +++++++ src/libvirt_private.syms | 3 + src/lxc/lxc_cgroup.c | 8 + src/lxc/lxc_container.c | 123 ++++++++++++-- src/util/vircgroup.c | 74 ++++++++- src/util/vircgroup.h | 2 + tests/domainschemadata/domain-caps-features.xml | 28 ++++ 9 files changed, 602 insertions(+), 25 deletions(-) create mode 100644 tests/domainschemadata/domain-caps-features.xml diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 33d0308..22eb098 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -3744,6 +3744,9 @@ <empty/> </element> </optional> + <optional> + <ref name="capabilities"/> + </optional> </interleave> </element> </optional> @@ -4311,6 +4314,200 @@ </element> </define> + <!-- Optional capabilities features --> + <define name="capabilities"> + <element name="capabilities"> + <ref name="capabilitiespolicy"/> + <interleave> + <optional> + <element name="audit_control"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="audit_write"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="block_suspend"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="chown"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="dac_override"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="dac_read_search"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="fowner"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="fsetid"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="ipc_lock"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="ipc_owner"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="kill"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="lease"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="linux_immutable"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="mac_admin"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="mac_override"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="mknod"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="net_admin"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="net_bind_service"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="net_broadcast"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="net_raw"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="setgid"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="setfcap"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="setpcap"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="setuid"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_admin"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_boot"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_chroot"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_module"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_nice"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_pacct"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_ptrace"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_rawio"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_resource"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_time"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="sys_tty_config"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="syslog"> + <ref name="featurestate"/> + </element> + </optional> + <optional> + <element name="wake_alarm"> + <ref name="featurestate"/> + </element> + </optional> + </interleave> + </element> + </define> + <define name="featurestate"> <attribute name="state"> <choice> @@ -4320,6 +4517,16 @@ </attribute> </define> + <define name="capabilitiespolicy"> + <attribute name="policy"> + <choice> + <value>default</value> + <value>allow</value> + <value>deny</value> + </choice> + </attribute> + </define> + <!-- Optional hypervisor extensions in their own namespace: QEmu diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 02c394f..9639401 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -147,18 +147,63 @@ VIR_ENUM_IMPL(virDomainFeature, VIR_DOMAIN_FEATURE_LAST, "viridian", "privnet", "hyperv", - "pvspinlock") + "pvspinlock", + "capabilities") VIR_ENUM_IMPL(virDomainFeatureState, VIR_DOMAIN_FEATURE_STATE_LAST, "default", "on", "off") +VIR_ENUM_IMPL(virDomainCapabilitiesPolicy, VIR_DOMAIN_CAPABILITIES_POLICY_LAST, + "default", + "allow", + "deny") + VIR_ENUM_IMPL(virDomainHyperv, VIR_DOMAIN_HYPERV_LAST, "relaxed", "vapic", "spinlocks") +VIR_ENUM_IMPL(virDomainCapsFeature, VIR_DOMAIN_CAPS_FEATURE_LAST, + "audit_control", + "audit_write", + "block_suspend", + "chown", + "dac_override", + "dac_read_search", + "fowner", + "fsetid", + "ipc_lock", + "ipc_owner", + "kill", + "lease", + "linux_immutable", + "mac_admin", + "mac_override", + "mknod", + "net_admin", + "net_bind_service", + "net_broadcast", + "net_raw", + "setgid", + "setfcap", + "setpcap", + "setuid", + "sys_admin", + "sys_boot", + "sys_chroot", + "sys_module", + "sys_nice", + "sys_pacct", + "sys_ptrace", + "sys_rawio", + "sys_resource", + "sys_time", + "sys_tty_config", + "syslog", + "wake_alarm") + VIR_ENUM_IMPL(virDomainLifecycle, VIR_DOMAIN_LIFECYCLE_LAST, "destroy", "restart", @@ -11877,6 +11922,22 @@ virDomainDefParseXML(xmlDocPtr xml, def->features[val] = VIR_DOMAIN_FEATURE_STATE_ON; break; + case VIR_DOMAIN_FEATURE_CAPABILITIES: + node = ctxt->node; + ctxt->node = nodes[i]; + if ((tmp = virXPathString("string(./@policy)", ctxt))) { + if ((def->features[val] = virDomainCapabilitiesPolicyTypeFromString(tmp)) == -1) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown state attribute '%s' of feature '%s'"), + tmp, virDomainFeatureTypeToString(val)); + goto error; + } + VIR_FREE(tmp); + } else { + def->features[val] = VIR_DOMAIN_FEATURE_STATE_DEFAULT; + } + ctxt->node = node; + break; case VIR_DOMAIN_FEATURE_PVSPINLOCK: node = ctxt->node; ctxt->node = nodes[i]; @@ -11985,6 +12046,37 @@ virDomainDefParseXML(xmlDocPtr xml, ctxt->node = node; } + if ((n = virXPathNodeSet("./features/capabilities/*", ctxt, &nodes)) < 0) + goto error; + + for (i = 0; i < n; i++) { + int val = virDomainCapsFeatureTypeFromString((const char *)nodes[i]->name); + if (val < 0) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unexpected capability feature '%s'"), nodes[i]->name); + goto error; + } + + if (val >= 0 && val < VIR_DOMAIN_CAPS_FEATURE_LAST) { + node = ctxt->node; + ctxt->node = nodes[i]; + + if ((tmp = virXPathString("string(./@state)", ctxt))) { + if ((def->caps_features[val] = virDomainFeatureStateTypeFromString(tmp)) == -1) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown state attribute '%s' of feature capability '%s'"), + tmp, virDomainFeatureTypeToString(val)); + goto error; + } + VIR_FREE(tmp); + } else { + def->caps_features[val] = VIR_DOMAIN_FEATURE_STATE_ON; + } + ctxt->node = node; + } + } + VIR_FREE(nodes); + if (virDomainEventActionParseXML(ctxt, "on_reboot", "string(./on_reboot[1])", &def->onReboot, @@ -17182,6 +17274,19 @@ verify(((VIR_DOMAIN_XML_INTERNAL_STATUS | VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST) & DUMPXML_FLAGS) == 0); +static bool +virDomainDefHasCapabilitiesFeatures(virDomainDefPtr def) +{ + size_t i; + + for (i = 0; i < VIR_DOMAIN_CAPS_FEATURE_LAST; i++) { + if (def->caps_features[i] != VIR_DOMAIN_FEATURE_STATE_DEFAULT) + return true; + } + + return false; +} + /* This internal version can accept VIR_DOMAIN_XML_INTERNAL_*, * whereas the public version cannot. Also, it appends to an existing * buffer (possibly with auto-indent), rather than flattening to string. @@ -17701,6 +17806,25 @@ virDomainDefFormatInternal(virDomainDefPtr def, virBufferAddLit(buf, "</hyperv>\n"); break; + case VIR_DOMAIN_FEATURE_CAPABILITIES: + if (def->features[i] == VIR_DOMAIN_CAPABILITIES_POLICY_DEFAULT && + !virDomainDefHasCapabilitiesFeatures(def)) + break; + + virBufferAsprintf(buf, "<capabilities policy='%s'>\n", + virDomainCapabilitiesPolicyTypeToString(def->features[i])); + virBufferAdjustIndent(buf, 2); + for (j = 0; j < VIR_DOMAIN_CAPS_FEATURE_LAST; j++) { + if (def->caps_features[j] != VIR_DOMAIN_FEATURE_STATE_DEFAULT) + virBufferAsprintf(buf, "<%s state='%s'/>\n", + virDomainCapsFeatureTypeToString(j), + virDomainFeatureStateTypeToString( + def->caps_features[j])); + } + virBufferAdjustIndent(buf, -2); + virBufferAddLit(buf, "</capabilities>\n"); + break; + case VIR_DOMAIN_FEATURE_LAST: break; } diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 1122eb2..7664d3f 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1528,6 +1528,7 @@ typedef enum { VIR_DOMAIN_FEATURE_PRIVNET, VIR_DOMAIN_FEATURE_HYPERV, VIR_DOMAIN_FEATURE_PVSPINLOCK, + VIR_DOMAIN_FEATURE_CAPABILITIES, VIR_DOMAIN_FEATURE_LAST } virDomainFeature; @@ -1549,6 +1550,56 @@ typedef enum { } virDomainHyperv; typedef enum { + VIR_DOMAIN_CAPABILITIES_POLICY_DEFAULT = 0, + VIR_DOMAIN_CAPABILITIES_POLICY_ALLOW, + VIR_DOMAIN_CAPABILITIES_POLICY_DENY, + + VIR_DOMAIN_CAPABILITIES_POLICY_LAST +} virDomainCapabilitiesPolicy; + +/* The capabilities are ordered alphabetically to help check for new ones */ +typedef enum { + VIR_DOMAIN_CAPS_FEATURE_AUDIT_CONTROL = 0, + VIR_DOMAIN_CAPS_FEATURE_AUDIT_WRITE, + VIR_DOMAIN_CAPS_FEATURE_BLOCK_SUSPEND, + VIR_DOMAIN_CAPS_FEATURE_CHOWN, + VIR_DOMAIN_CAPS_FEATURE_DAC_OVERRIDE, + VIR_DOMAIN_CAPS_FEATURE_DAC_READ_SEARCH, + VIR_DOMAIN_CAPS_FEATURE_FOWNER, + VIR_DOMAIN_CAPS_FEATURE_FSETID, + VIR_DOMAIN_CAPS_FEATURE_IPC_LOCK, + VIR_DOMAIN_CAPS_FEATURE_IPC_OWNER, + VIR_DOMAIN_CAPS_FEATURE_KILL, + VIR_DOMAIN_CAPS_FEATURE_LEASE, + VIR_DOMAIN_CAPS_FEATURE_LINUX_IMMUTABLE, + VIR_DOMAIN_CAPS_FEATURE_MAC_ADMIN, + VIR_DOMAIN_CAPS_FEATURE_MAC_OVERRIDE, + VIR_DOMAIN_CAPS_FEATURE_MKNOD, + VIR_DOMAIN_CAPS_FEATURE_NET_ADMIN, + VIR_DOMAIN_CAPS_FEATURE_NET_BIND_SERVICE, + VIR_DOMAIN_CAPS_FEATURE_NET_BROADCAST, + VIR_DOMAIN_CAPS_FEATURE_NET_RAW, + VIR_DOMAIN_CAPS_FEATURE_SETGID, + VIR_DOMAIN_CAPS_FEATURE_SETFCAP, + VIR_DOMAIN_CAPS_FEATURE_SETPCAP, + VIR_DOMAIN_CAPS_FEATURE_SETUID, + VIR_DOMAIN_CAPS_FEATURE_SYS_ADMIN, + VIR_DOMAIN_CAPS_FEATURE_SYS_BOOT, + VIR_DOMAIN_CAPS_FEATURE_SYS_CHROOT, + VIR_DOMAIN_CAPS_FEATURE_SYS_MODULE, + VIR_DOMAIN_CAPS_FEATURE_SYS_NICE, + VIR_DOMAIN_CAPS_FEATURE_SYS_PACCT, + VIR_DOMAIN_CAPS_FEATURE_SYS_PTRACE, + VIR_DOMAIN_CAPS_FEATURE_SYS_RAWIO, + VIR_DOMAIN_CAPS_FEATURE_SYS_RESOURCE, + VIR_DOMAIN_CAPS_FEATURE_SYS_TIME, + VIR_DOMAIN_CAPS_FEATURE_SYS_TTY_CONFIG, + VIR_DOMAIN_CAPS_FEATURE_SYSLOG, + VIR_DOMAIN_CAPS_FEATURE_WAKE_ALARM, + VIR_DOMAIN_CAPS_FEATURE_LAST +} virDomainCapsFeature; + +typedef enum { VIR_DOMAIN_LIFECYCLE_DESTROY, VIR_DOMAIN_LIFECYCLE_RESTART, VIR_DOMAIN_LIFECYCLE_RESTART_RENAME, @@ -1917,6 +1968,9 @@ struct _virDomainDef { int hyperv_features[VIR_DOMAIN_HYPERV_LAST]; unsigned int hyperv_spinlocks; + /* This options are of type virDomainFeatureState: ON = keep, OFF = drop */ + int caps_features[VIR_DOMAIN_CAPS_FEATURE_LAST]; + virDomainClockDef clock; size_t ngraphics; @@ -2534,6 +2588,8 @@ VIR_ENUM_DECL(virDomainBoot) VIR_ENUM_DECL(virDomainBootMenu) VIR_ENUM_DECL(virDomainFeature) VIR_ENUM_DECL(virDomainFeatureState) +VIR_ENUM_DECL(virDomainCapabilitiesPolicy) +VIR_ENUM_DECL(virDomainCapsFeature) VIR_ENUM_DECL(virDomainLifecycle) VIR_ENUM_DECL(virDomainLifecycleCrash) VIR_ENUM_DECL(virDomainPMState) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index a793b4c..ef92509 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -139,6 +139,8 @@ virDomainBlockedReasonTypeFromString; virDomainBlockedReasonTypeToString; virDomainBootMenuTypeFromString; virDomainBootMenuTypeToString; +virDomainCapabilitiesPolicyTypeToString; +virDomainCapsFeatureTypeToString; virDomainChrConsoleTargetTypeFromString; virDomainChrConsoleTargetTypeToString; virDomainChrDefForeach; @@ -1027,6 +1029,7 @@ virBufferVasprintf; # util/vircgroup.h virCgroupAddTask; virCgroupAddTaskController; +virCgroupAllowAllDevices; virCgroupAllowDevice; virCgroupAllowDeviceMajor; virCgroupAllowDevicePath; diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c index 39e30ad..4d107ef 100644 --- a/src/lxc/lxc_cgroup.c +++ b/src/lxc/lxc_cgroup.c @@ -363,6 +363,14 @@ static int virLXCCgroupSetupDeviceACL(virDomainDefPtr def, if (virCgroupDenyAllDevices(cgroup) < 0) goto cleanup; + /* white list mknod if CAP_MKNOD has to be kept */ + int capMknod = def->caps_features[VIR_DOMAIN_CAPS_FEATURE_MKNOD]; + if (capMknod == VIR_DOMAIN_FEATURE_STATE_ON) { + if (virCgroupAllowAllDevices(cgroup, + VIR_CGROUP_DEVICE_MKNOD) < 0) + goto cleanup; + } + for (i = 0; devices[i].type != 0; i++) { virLXCCgroupDevicePolicyPtr dev = &devices[i]; if (virCgroupAllowDevice(cgroup, diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index fd8ab16..d0ca182 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -1732,25 +1732,115 @@ static int lxcContainerResolveSymlinks(virDomainDefPtr vmDef) * host system, since they are not currently "containerized" */ #if WITH_CAPNG -static int lxcContainerDropCapabilities(bool keepReboot) +static int lxcContainerDropCapabilities(virDomainDefPtr def, + bool keepReboot) { int ret; + size_t i; + int policy = def->features[VIR_DOMAIN_FEATURE_CAPABILITIES]; + + /* Maps virDomainCapsFeature to CAPS_* */ + static unsigned int capsMapping[] = {CAP_AUDIT_CONTROL, + CAP_AUDIT_WRITE, + CAP_BLOCK_SUSPEND, + CAP_CHOWN, + CAP_DAC_OVERRIDE, + CAP_DAC_READ_SEARCH, + CAP_FOWNER, + CAP_FSETID, + CAP_IPC_LOCK, + CAP_IPC_OWNER, + CAP_KILL, + CAP_LEASE, + CAP_LINUX_IMMUTABLE, + CAP_MAC_ADMIN, + CAP_MAC_OVERRIDE, + CAP_MKNOD, + CAP_NET_ADMIN, + CAP_NET_BIND_SERVICE, + CAP_NET_BROADCAST, + CAP_NET_RAW, + CAP_SETGID, + CAP_SETFCAP, + CAP_SETPCAP, + CAP_SETUID, + CAP_SYS_ADMIN, + CAP_SYS_BOOT, + CAP_SYS_CHROOT, + CAP_SYS_MODULE, + CAP_SYS_NICE, + CAP_SYS_PACCT, + CAP_SYS_PTRACE, + CAP_SYS_RAWIO, + CAP_SYS_RESOURCE, + CAP_SYS_TIME, + CAP_SYS_TTY_CONFIG, + CAP_SYSLOG, + CAP_WAKE_ALARM}; capng_get_caps_process(); - if ((ret = capng_updatev(CAPNG_DROP, - CAPNG_EFFECTIVE | CAPNG_PERMITTED | - CAPNG_INHERITABLE | CAPNG_BOUNDING_SET, - CAP_SYS_MODULE, /* No kernel module loading */ - CAP_SYS_TIME, /* No changing the clock */ - CAP_MKNOD, /* No creating device nodes */ - CAP_AUDIT_CONTROL, /* No messing with auditing status */ - CAP_MAC_ADMIN, /* No messing with LSM config */ - keepReboot ? -1 : CAP_SYS_BOOT, /* No use of reboot */ - -1)) < 0) { - virReportError(VIR_ERR_INTERNAL_ERROR, - _("Failed to remove capabilities: %d"), ret); - return -1; + /* Make sure we drop everything if required by the user */ + if (policy == VIR_DOMAIN_CAPABILITIES_POLICY_DENY) + capng_clear(CAPNG_SELECT_BOTH); + + /* Apply all single capabilities changes */ + for (i = 0; i < VIR_DOMAIN_CAPS_FEATURE_LAST; i++) { + bool toDrop = false; + int state = def->caps_features[i]; + + switch ((virDomainCapabilitiesPolicy) policy) { + + case VIR_DOMAIN_CAPABILITIES_POLICY_DENY: + if (state == VIR_DOMAIN_FEATURE_STATE_ON && + (ret = capng_update(CAPNG_ADD, + CAPNG_EFFECTIVE | CAPNG_PERMITTED | + CAPNG_INHERITABLE | CAPNG_BOUNDING_SET, + capsMapping[i])) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Failed to add capability %s: %d"), + virDomainCapsFeatureTypeToString(i), ret); + return -1; + } + break; + + case VIR_DOMAIN_CAPABILITIES_POLICY_DEFAULT: + switch ((virDomainCapsFeature) i) { + case VIR_DOMAIN_CAPS_FEATURE_SYS_BOOT: /* No use of reboot */ + toDrop = !keepReboot && (state != VIR_DOMAIN_FEATURE_STATE_ON); + break; + case VIR_DOMAIN_CAPS_FEATURE_SYS_MODULE: /* No kernel module loading */ + case VIR_DOMAIN_CAPS_FEATURE_SYS_TIME: /* No changing the clock */ + case VIR_DOMAIN_CAPS_FEATURE_MKNOD: /* No creating device nodes */ + case VIR_DOMAIN_CAPS_FEATURE_AUDIT_CONTROL: /* No messing with auditing status */ + case VIR_DOMAIN_CAPS_FEATURE_MAC_ADMIN: /* No messing with LSM config */ + toDrop = (state != VIR_DOMAIN_FEATURE_STATE_ON); + break; + default: /* User specified capabilities to drop */ + toDrop = (state == VIR_DOMAIN_FEATURE_STATE_OFF); + } + /* Fallthrough */ + + case VIR_DOMAIN_CAPABILITIES_POLICY_ALLOW: + if (policy == VIR_DOMAIN_CAPABILITIES_POLICY_ALLOW) + toDrop = state == VIR_DOMAIN_FEATURE_STATE_OFF; + + if (toDrop && (ret = capng_update(CAPNG_DROP, + CAPNG_EFFECTIVE | CAPNG_PERMITTED | + CAPNG_INHERITABLE | CAPNG_BOUNDING_SET, + capsMapping[i])) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("Failed to remove capability %s: %d"), + virDomainCapsFeatureTypeToString(i), ret); + return -1; + } + break; + + default: + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("Unsupported capabilities policy: %s"), + virDomainCapabilitiesPolicyTypeToString(policy)); + } } if ((ret = capng_apply(CAPNG_SELECT_BOTH)) < 0) { @@ -1768,7 +1858,8 @@ static int lxcContainerDropCapabilities(bool keepReboot) return 0; } #else -static int lxcContainerDropCapabilities(bool keepReboot ATTRIBUTE_UNUSED) +static int lxcContainerDropCapabilities(virDomainDefPtr def ATTRIBUTE_UNUSED, + bool keepReboot ATTRIBUTE_UNUSED) { VIR_WARN("libcap-ng support not compiled in, unable to clear capabilities"); return 0; @@ -1874,7 +1965,7 @@ static int lxcContainerChild(void *data) } /* drop a set of root capabilities */ - if (lxcContainerDropCapabilities(!!hasReboot) < 0) + if (lxcContainerDropCapabilities(vmDef, !!hasReboot) < 0) goto cleanup; if (lxcContainerSendContinue(argv->handshakefd) < 0) { diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c index c578bd0..7f1bc5f 100644 --- a/src/util/vircgroup.c +++ b/src/util/vircgroup.c @@ -2622,6 +2622,62 @@ virCgroupDenyAllDevices(virCgroupPtr group) "a"); } +static int +virCgroupAllowDevices(virCgroupPtr group, char type, const char *device, int perms) +{ + int ret = -1; + char *devstr = NULL; + + if (virAsprintf(&devstr, "%c %s %s%s%s", type, device, + perms & VIR_CGROUP_DEVICE_READ ? "r" : "", + perms & VIR_CGROUP_DEVICE_WRITE ? "w" : "", + perms & VIR_CGROUP_DEVICE_MKNOD ? "m" : "") < 0) + goto cleanup; + + if (virCgroupSetValueStr(group, + VIR_CGROUP_CONTROLLER_DEVICES, + "devices.allow", + devstr) < 0) + goto cleanup; + + ret = 0; + + cleanup: + VIR_FREE(devstr); + return ret; +} + +/** + * virCgroupAllowAllDevices: + * + * Allows the permissiong for all devices by setting lines similar + * to these ones (obviously the 'm' permission is an example): + * + * 'b *:* m' + * 'c *:* m' + * + * @group: The cgroup to allow devices for + * @perms: Bitwise or of VIR_CGROUP_DEVICE permission bits to allow + * + * Returns: 0 on success + */ +int +virCgroupAllowAllDevices(virCgroupPtr group, int perms) +{ + int ret = -1; + + if (virCgroupAllowDevices(group, 'b', "*:*", perms) < 0) + goto cleanup; + + if (virCgroupAllowDevices(group, 'c', "*:*", perms) < 0) + goto cleanup; + + ret = 0; + + cleanup: + return ret; +} + /** * virCgroupAllowDevice: @@ -2641,16 +2697,10 @@ virCgroupAllowDevice(virCgroupPtr group, char type, int major, int minor, int ret = -1; char *devstr = NULL; - if (virAsprintf(&devstr, "%c %i:%i %s%s%s", type, major, minor, - perms & VIR_CGROUP_DEVICE_READ ? "r" : "", - perms & VIR_CGROUP_DEVICE_WRITE ? "w" : "", - perms & VIR_CGROUP_DEVICE_MKNOD ? "m" : "") < 0) + if (virAsprintf(&devstr, "%i:%i", major, minor) < 0) goto cleanup; - if (virCgroupSetValueStr(group, - VIR_CGROUP_CONTROLLER_DEVICES, - "devices.allow", - devstr) < 0) + if (virCgroupAllowDevices(group, type, devstr, perms) < 0) goto cleanup; ret = 0; @@ -4202,6 +4252,14 @@ virCgroupGetCpusetCpus(virCgroupPtr group ATTRIBUTE_UNUSED, return -1; } +int +virCgroupAllowAllDevices(virCgroupPtr groupi ATTRIBUTE_UNUSED, + int perms ATTRIBUTE_UNUSED) +{ + virReportSystemError(ENOSYS, "%s", + _("Control groups not supported on this platform")); + return -1; +} int virCgroupDenyAllDevices(virCgroupPtr group ATTRIBUTE_UNUSED) diff --git a/src/util/vircgroup.h b/src/util/vircgroup.h index 7bb46bf..358562f 100644 --- a/src/util/vircgroup.h +++ b/src/util/vircgroup.h @@ -175,6 +175,8 @@ enum { int virCgroupDenyAllDevices(virCgroupPtr group); +int virCgroupAllowAllDevices(virCgroupPtr group, int perms); + int virCgroupAllowDevice(virCgroupPtr group, char type, int major, diff --git a/tests/domainschemadata/domain-caps-features.xml b/tests/domainschemadata/domain-caps-features.xml new file mode 100644 index 0000000..4f118b2 --- /dev/null +++ b/tests/domainschemadata/domain-caps-features.xml @@ -0,0 +1,28 @@ +<domain type='lxc'> + <name>demo</name> + <uuid>8369f1ac-7e46-e869-4ca5-759d51478066</uuid> + <os> + <type>exe</type> + <init>/sh</init> + </os> + <features> + <capabilities policy="deny"> + <mknod state="on"/> + </capabilities> + </features> + <resource> + <partition>/virtualmachines</partition> + </resource> + <memory unit='KiB'>500000</memory> + <devices> + <filesystem type='mount'> + <source dir='/root/container'/> + <target dir='/'/> + </filesystem> + <filesystem type='mount'> + <source dir='/home'/> + <target dir='/home'/> + </filesystem> + <console type='pty'/> + </devices> +</domain> -- 1.8.4.5

--- docs/drvlxc.html.in | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/docs/drvlxc.html.in b/docs/drvlxc.html.in index fc4bc20..403ce24 100644 --- a/docs/drvlxc.html.in +++ b/docs/drvlxc.html.in @@ -540,6 +540,53 @@ debootstrap, whatever) under /opt/vm-1-root: &lt;/domain&gt; </pre> +<h2><a name="capabilities">Altering the available capabilities</a></h2> + +<p> +By default the libvirt LXC driver drops some capabilities among which CAP_MKNOD. +However <span class="since">since 1.2.6</span> libvirt can be told to keep or +drop some capabilities using a domain configuration like the following: +</p> +<pre> +... +&lt;features&gt; + &lt;capabilities policy='default'&gt; + &lt;mknod state='on'/&gt; + &lt;sys_chroot state='off'/&gt; + &lt;/capabilities&gt; +&lt;/features&gt; +... +</pre> +<p> +The capabilities children elements are named after the capabilities as defined in +<code>man 7 capabilities</code>. An <code>off</code> state tells libvirt to drop the +capability, while an <code>on</code> state will force to keep the capability even though +this one is dropped by default. +</p> +<p> +The <code>policy</code> attribute can be one of <code>default</code>, <code>allow</code> +or <code>deny</code>. It defines the default rules for capabilities: either keep the +default behavior that is dropping a few selected capabilities, or keep all capabilities +or drop all capabilities. The interest of <code>allow</code> and <code>deny</code> is that +they guarantee that all capabilities will be kept (or removed) even if new ones are added +later. +</p> +<p> +The following example, drops all capabilities but CAP_MKNOD: +</p> +<pre> +... +&lt;features&gt; + &lt;capabilities policy='deny'&gt; + &lt;mknod state='on'/&gt; + &lt;/capabilities&gt; +&lt;/features&gt; +... +</pre> +<p> +Note that allowing capabilities that are normally dropped by default can seriously +affect the security of the container and the host. +</p> <h2><a name="usage">Container usage / management</a></h2> -- 1.8.4.5