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Daniel P. Berrange wrote:
This patch implements the behaviour I was refering to earlier,
whereby
the domain XML explicitly says whether the security label is a statically
pre-defined one, or dynamically generated on VM boot by libvirtd
So when creating a new guest, apps like virt-install have 2 options:
- Leave out the <seclabel> tag completely
-> If no security driver is active, just works as normal unconfined VM
I
want to make sure of terminology. The VM will be confined, but will
not be separated. IE the host machine will be protected from the VM,
while other VM's will not be. svirt is concerned with protecting VM's
from each other. Normal SELinux protects the Apache server from rogue
VMs. If we want to have a truly unconfined vm, we need additional
policy. I would suggest permissive mode or a permissive domain.
semanage permissive -a qemu_t
Would give you this.
-> If a security driver is active, a dynamic seclabel is
generated
<seclabel type='dynamic' model='selinux'>
<label>system_u:system_r:qemu_t:s0:c424,c719</label>
<imagelabel>system_u:object_r:virt_image_t:s0:c424,c719</imagelabel>
</seclabel>
- Add an explicit <seclabel> tag with type='static' attribute
-> Security driver uses the defined label & imagelabel
<seclabel type='static' model='selinux'>
<label>system_u:system_r:qemu_t:s0:c25,c100</label>
<imagelabel>system_u:system_r:virt_image_t:s0:c25,c100</imagelabel>
</seclabel>
Not sure imagelabel is required in the second case since, libvirt will
not change the label.
This is the biggest difference between static and dynamic, static will
never run setfilecon, while dynamic runs it at startup and shutdown.
DYNAMIC:
start
setfilecon(image, imagelabel)
setexeccon(label)
exec()
Finish
ChildExit()
setfilecon(image, DEFAULT_LABEL)
Exit()
STATIC:
start
setexecon(label)
exec()
Finish:
ChildExit()
Exit()
A static seclabel is visible in the XML, at all times, whether the VM
is
active or inactive.
A dynamic seclabel is only visible when the VM is running, since it is
auto-generated at VM boot. If you migrate the VM, or save/restore it,
the dynamic seclabel will change on each boot. The seclabel isn't visible
when not running, or if asking for the inactive XML dump
This patch implements parsing of the 'type' attribute, and makes the
seclabel generation key off this attribute.
It also adds the 'imagelabel' XML element, since that was being used
internally, but was not including in the XML output, or parsing
routines, making it impossible to specify a pre-defined image label
or see the dyanmic one
domain_conf.c | 65 +++++++++++++++++++++++++++++++++++++++++++----------
domain_conf.h | 9 +++++++
qemu_driver.c | 13 ++++++++--
security_selinux.c | 1
4 files changed, 73 insertions(+), 15 deletions(-)
Daniel
Index: src/domain_conf.c
===================================================================
RCS file: /data/cvs/libvirt/src/domain_conf.c,v
retrieving revision 1.70
diff -u -p -r1.70 domain_conf.c
--- src/domain_conf.c 3 Mar 2009 09:44:42 -0000 1.70
+++ src/domain_conf.c 3 Mar 2009 15:36:02 -0000
@@ -168,6 +168,10 @@ VIR_ENUM_IMPL(virDomainState, VIR_DOMAIN
"shutoff",
"crashed")
+VIR_ENUM_IMPL(virDomainSeclabel, VIR_DOMAIN_SECLABEL_LAST,
+ "dynamic",
+ "static")
+
#define virDomainReportError(conn, code, fmt...) \
virReportErrorHelper(conn, VIR_FROM_DOMAIN, code, __FILE__, \
__FUNCTION__, __LINE__, fmt)
@@ -1847,24 +1851,46 @@ static int virDomainLifecycleParseXML(vi
static int
virSecurityLabelDefParseXML(virConnectPtr conn,
const virDomainDefPtr def,
- xmlXPathContextPtr ctxt)
+ xmlXPathContextPtr ctxt,
+ int flags)
{
char *p;
if (virXPathNode(conn, "./seclabel", ctxt) == NULL)
return 0;
- p = virXPathStringLimit(conn, "string(./seclabel/label[1])",
+ p = virXPathStringLimit(conn, "string(./seclabel/@type)",
VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
if (p == NULL)
goto error;
- def->seclabel.label = p;
-
- p = virXPathStringLimit(conn, "string(./seclabel/@model)",
- VIR_SECURITY_MODEL_BUFLEN-1, ctxt);
- if (p == NULL)
+ if ((def->seclabel.type = virDomainSeclabelTypeFromString(p)) < 0)
goto error;
- def->seclabel.model = p;
+ VIR_FREE(p);
+
+ /* Only parse details, if using static labels, or
+ * if the 'live' VM XML is requested
+ */
+ if (def->seclabel.type == VIR_DOMAIN_SECLABEL_STATIC ||
+ !(flags & VIR_DOMAIN_XML_INACTIVE)) {
+ p = virXPathStringLimit(conn, "string(./seclabel/@model)",
+ VIR_SECURITY_MODEL_BUFLEN-1, ctxt);
+ if (p == NULL)
+ goto error;
+ def->seclabel.model = p;
+
+ p = virXPathStringLimit(conn, "string(./seclabel/label[1])",
+ VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
+ if (p == NULL)
+ goto error;
+ def->seclabel.label = p;
+
+ p = virXPathStringLimit(conn, "string(./seclabel/imagelabel[1])",
+ VIR_SECURITY_LABEL_BUFLEN-1, ctxt);
+ if (p == NULL)
+ goto error;
+ def->seclabel.imagelabel = p;
+
+ }
return 0;
@@ -2458,7 +2484,7 @@ static virDomainDefPtr virDomainDefParse
VIR_FREE(nodes);
/* analysis of security label */
- if (virSecurityLabelDefParseXML(conn, def, ctxt) == -1)
+ if (virSecurityLabelDefParseXML(conn, def, ctxt, flags) == -1)
goto error;
return def;
@@ -3480,9 +3506,24 @@ char *virDomainDefFormat(virConnectPtr c
virBufferAddLit(&buf, " </devices>\n");
if (def->seclabel.model) {
- virBufferEscapeString(&buf, " <seclabel
model='%s'>\n", def->seclabel.model);
- virBufferEscapeString(&buf, " <label>%s</label>\n",
def->seclabel.label);
- virBufferAddLit(&buf, " </seclabel>\n");
+ const char *sectype = virDomainSeclabelTypeToString(def->seclabel.type);
+ if (!sectype)
+ goto cleanup;
+ if (!def->seclabel.label ||
+ (def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC &&
+ (flags & VIR_DOMAIN_XML_INACTIVE))) {
+ virBufferVSprintf(&buf, " <seclabel type='%s'
model='%s'/>\n",
+ sectype, def->seclabel.model);
+ } else {
+ virBufferVSprintf(&buf, " <seclabel type='%s'
model='%s'>\n",
+ sectype, def->seclabel.model);
+ virBufferEscapeString(&buf, "
<label>%s</label>\n",
+ def->seclabel.label);
+ if (def->seclabel.imagelabel)
+ virBufferEscapeString(&buf, "
<imagelabel>%s</imagelabel>\n",
+ def->seclabel.imagelabel);
+ virBufferAddLit(&buf, " </seclabel>\n");
+ }
}
virBufferAddLit(&buf, "</domain>\n");
Index: src/domain_conf.h
===================================================================
RCS file: /data/cvs/libvirt/src/domain_conf.h,v
retrieving revision 1.39
diff -u -p -r1.39 domain_conf.h
--- src/domain_conf.h 3 Mar 2009 09:44:42 -0000 1.39
+++ src/domain_conf.h 3 Mar 2009 15:36:02 -0000
@@ -410,6 +410,13 @@ struct _virDomainOSDef {
char *bootloaderArgs;
};
+enum virDomainSeclabelType {
+ VIR_DOMAIN_SECLABEL_DYNAMIC,
+ VIR_DOMAIN_SECLABEL_STATIC,
+
+ VIR_DOMAIN_SECLABEL_LAST,
+};
+
/* Security configuration for domain */
typedef struct _virSecurityLabelDef virSecurityLabelDef;
typedef virSecurityLabelDef *virSecurityLabelDefPtr;
@@ -417,6 +424,7 @@ struct _virSecurityLabelDef {
char *model; /* name of security model */
char *label; /* security label string */
char *imagelabel; /* security image label string */
+ int type;
};
#define VIR_DOMAIN_CPUMASK_LEN 1024
@@ -650,5 +658,6 @@ VIR_ENUM_DECL(virDomainInputBus)
VIR_ENUM_DECL(virDomainGraphics)
/* from libvirt.h */
VIR_ENUM_DECL(virDomainState)
+VIR_ENUM_DECL(virDomainSeclabel)
#endif /* __DOMAIN_CONF_H */
Index: src/qemu_driver.c
===================================================================
RCS file: /data/cvs/libvirt/src/qemu_driver.c,v
retrieving revision 1.213
diff -u -p -r1.213 qemu_driver.c
--- src/qemu_driver.c 3 Mar 2009 15:18:24 -0000 1.213
+++ src/qemu_driver.c 3 Mar 2009 15:36:02 -0000
@@ -1314,9 +1314,9 @@ static int qemudStartVMDaemon(virConnect
hookData.vm = vm;
hookData.driver = driver;
- /* If you are using a SecurityDriver and there was no security label in
- database, then generate a security label for isolation */
- if (vm->def->seclabel.label == NULL &&
+ /* If you are using a SecurityDriver with dynamic labelling,
+ then generate a security label for isolation */
+ if (vm->def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC &&
driver->securityDriver &&
driver->securityDriver->domainGenSecurityLabel &&
driver->securityDriver->domainGenSecurityLabel(conn, vm) < 0)
@@ -1525,6 +1525,13 @@ static void qemudShutdownVMDaemon(virCon
if (driver->securityDriver)
driver->securityDriver->domainRestoreSecurityLabel(conn, vm);
+ /* Clear out dynamically assigned labels */
+ if (vm->def->seclabel.type == VIR_DOMAIN_SECLABEL_DYNAMIC) {
+ VIR_FREE(vm->def->seclabel.model);
+ VIR_FREE(vm->def->seclabel.label);
+ VIR_FREE(vm->def->seclabel.imagelabel);
+ }
+
if (qemudRemoveDomainStatus(conn, driver, vm) < 0) {
VIR_WARN(_("Failed to remove domain status for %s"),
vm->def->name);
Index: src/security_selinux.c
===================================================================
RCS file: /data/cvs/libvirt/src/security_selinux.c,v
retrieving revision 1.2
diff -u -p -r1.2 security_selinux.c
--- src/security_selinux.c 3 Mar 2009 15:18:24 -0000 1.2
+++ src/security_selinux.c 3 Mar 2009 15:36:02 -0000
@@ -161,6 +161,7 @@ SELinuxGenSecurityLabel(virConnectPtr co
char *scontext = NULL;
int c1 = 0;
int c2 = 0;
+
if ( ( vm->def->seclabel.label ) ||
( vm->def->seclabel.model ) ||
( vm->def->seclabel.imagelabel )) {
Patch looks good.
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