A preparatory patch for DHCP snooping where we want to be able to
differentiate between a VM's interface using the tuple of
<VM UUID, Interface MAC address>. We assume that MAC addresses could
possibly be re-used between different networks (VLANs) thus do not only
want to rely on the MAC address to identify an interface.
At the current 'final destination' in virNWFilterInstantiate I am leaving
the vmuuid parameter as ATTRIBUTE_UNUSED until the DHCP snooping patches arrive.
(we may not post the DHCP snooping patches for 0.9.9, though)
Mostly this is a pretty trivial patch. On the lowest layers, in lxc_driver
and uml_conf, I am passing the virDomainDefPtr around until I am passing
only the VM's uuid into the NWFilter calls.
This patch cleans up return codes in the nwfilter subsystem.
Some functions in nwfilter_conf.c (validators and formatters) are
keeping their bool return for now and I am converting their return
code to true/false.
All other functions now have failure return codes of -1 and success
of 0.
[I searched for all occurences of ' 1;' and checked all 'if ' and
adapted where needed. After that I did a grep for 'NWFilter' in the source
tree.]
In preparation of DHCP Snooping and the detection of multiple IP
addresses per interface:
The hash table that is used to collect the detected IP address of an
interface can so far only handle one IP address per interface. With
this patch we extend this to allow it to handle a list of IP addresses.
Above changes the returned variable type of virNWFilterGetIpAddrForIfname()
from char * to virNWFilterVarValuePtr; adapt all existing functions calling
this function.
NWFilters can be provided name-value pairs using the following
XML notation:
<filterref filter='xyz'>
<parameter name='PORT' value='80'/>
<parameter name='VAL' value='abc'/>
</filterref>
The internal representation currently is so that a name is stored as a
string and the value as well. This patch now addresses the value part of it
and introduces a data structure for storing a value either as a simple
value or as an array for later support of lists.
This patch adjusts all code that was handling the values in hash tables
and makes it use the new data type.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Move the ifaceMacvtapLinkDump and ifaceGetNthParent functions
into virnetdevvportprofile.c since they are specific to that
code. This avoids polluting the headers with the Linux specific
netlink data types
* src/util/interface.c, src/util/interface.h: Move
ifaceMacvtapLinkDump and ifaceGetNthParent functions and delete
remaining file
* src/util/virnetdevvportprofile.c: Add ifaceMacvtapLinkDump
and ifaceGetNthParent functions
* src/network/bridge_driver.c, src/nwfilter/nwfilter_gentech_driver.c,
src/nwfilter/nwfilter_learnipaddr.c, src/util/virnetdevmacvlan.c:
Remove include of interface.h
Rename the ifaceCheck method to virNetDevValidateConfig and change
so that it always raises an error and returns -1 on error.
* src/util/interface.c, src/util/interface.h: Rename ifaceCheck
to virNetDevValidateConfig
* src/nwfilter/nwfilter_gentech_driver.c,
src/nwfilter/nwfilter_learnipaddr.c: Update for API rename
Rename the ifaceGetIndex method to virNetDevGetIndex and
ifaceGetVlanID to virNetDevGetVLanID. Also change the error
reporting behaviour to always raise errors and return -1 on
failure
* util/interface.c, util/interface.h: Rename ifaceGetIndex
and ifaceGetVLAN
* nwfilter/nwfilter_gentech_driver.c, nwfilter/nwfilter_learnipaddr.c,
nwfilter/nwfilter_learnipaddr.c, util/virnetdevvportprofile.c: Update
for API renames and error handling changes
The ifaceUp, ifaceDown, ifaceCtrl & ifaceIsUp APIs can be replaced
with calls to virNetDevSetOnline and virNetDevIsOnline
* src/util/interface.c, src/util/interface.h: Delete ifaceUp,
ifaceDown, ifaceCtrl & ifaceIsUp
* src/nwfilter/nwfilter_gentech_driver.c, src/util/macvtap.c:
Update to use virNetDevSetOnline and virNetDevIsOnline
All of the functions in util/interface.c were returning 0 on success,
but some returned -1 on error, and some returned a positive value
(usually the value of errno, but sometimes just 1). Libvirt's standard
is to return < 0 on error (in the case of functions that need to
return errno, -errno is returned.
This patch modifies all functions in interface.c to consistently
return < 0 on error, and makes changes to callers of those functions
where necessary.
This is in response to bugzilla 664629
https://bugzilla.redhat.com/show_bug.cgi?id=664629
The patch below returns an appropriate error message if the chain of
nwfilters is found to contain unresolvable variables and therefore
cannot be instantiated.
Example: The following XMl added to a domain:
<interface type='bridge'>
<mac address='52:54:00:9f:80:45'/>
<source bridge='virbr0'/>
<model type='virtio'/>
<filterref filter='test'/>
</interface>
that references the following filter
<filter name='test' chain='root'>
<filterref filter='clean-traffic'/>
<filterref filter='allow-dhcp-server'/>
</filter>
now displays upon 'virsh start mydomain'
error: Failed to start domain mydomain
error: internal error Cannot instantiate filter due to unresolvable variable: DHCPSERVER
'DHPCSERVER' is contained in allow-dhcp-server.
Relax the restriction that the hash table key must be a string
by allowing an arbitrary hash code generator + comparison func
to be provided
* util/hash.c, util/hash.h: Allow any pointer as a key
* internal.h: Include stdbool.h as standard.
* conf/domain_conf.c, conf/domain_conf.c,
conf/nwfilter_params.c, nwfilter/nwfilter_gentech_driver.c,
nwfilter/nwfilter_gentech_driver.h, nwfilter/nwfilter_learnipaddr.c,
qemu/qemu_command.c, qemu/qemu_driver.c,
qemu/qemu_process.c, uml/uml_driver.c,
xen/xm_internal.c: s/char */void */ in hash callbacks
Now that the virHash handling functions call virReportOOMError by
themselves when needed, users of the virHash API no longer need to
do it by themselves. Since users of the virHash API were not
consistently calling virReportOOMError after memory failures from
the virHash code, this has the added benefit of making OOM
reporting from this code more consistent and reliable.
When run non-root the nwfilter driver logs error messages about
being unable to find iptables/ebtables commands (they are in
/sbin which isn't in $PATH). The nwfilter driver can't ever work
as non-root, so simply skip it entirely thus avoiding the error
messages
* src/conf/nwfilter_conf.h, src/nwfilter/nwfilter_driver.c,
src/nwfilter/nwfilter_gentech_driver.c,
src/nwfilter/nwfilter_gentech_driver.h: Pass 'bool privileged'
flag down to final driver impl
* src/nwfilter/nwfilter_ebiptables_driver.c: Skip initialization
if not privileged
The public object is called NWFilter but the corresponding private
object is called NWFilterPool. I don't see compelling reasons for this
Pool suffix. One might argue that an NWFilter is a "pool" of rules, etc.
Remove the Pool suffix from NWFilterPool. No functional change included.
The IP address learning thread was causing a deadlock when it instantiated a filter while a filter update/change was ongoing. The reason for this was the ordering of locks due to the following calls
virNWFilterUnlockFilterUpdates()
virNWFilterPoolObjFindByName()
The below patch now puts the order of the locks in the above shown order when instantiating the filter from the IP address learning thread.
When a filter is updated, only those interfaces must have their old
rules cleared that either reference the filter directly or indirectly
through another filter. Remember between the different steps of the
instantiation of the filters which interfaces must be skipped. I am
using a hash map to remember the names of the interfaces and store a
bogus pointer to ~0 into it that need not be freed.
For the decision on whether to instantiate the rules, the check for a
pending IP address learn request is not sufficient since then only the
thread could instantiate the rules. So, a boolean needs to be passed
when the thread instantiates the filter rules late and the IP address
learn request is still pending in order to override the check for the
pending learn request. If the rules are to be updated while the thread
is active, this will not be done immediately but the thread will do that
later on.
Introduce a function to notify the IP address learning
thread to terminate and thus release the lock on the interface.
Notify the thread before grabbing the lock on the interface
and tearing down the rules. This prevents a 'virsh destroy' to
tear down the rules that the IP address learning thread has
applied.
- using INT_BUFSIZE_BOUND() to determine the length of the buffersize
for printing and integer into
- not explicitly initializing static var threadsTerminate to false
anymore, since that's done automatically
Changes after V2:
- removed while looks in case of OOM error
- removed on ifaceDown() call
- preceding one ifaceDown() call with an ifaceCheck() call
Since the name of an interface can be the same between stops and starts
of different VMs I have to switch the IP address learning thread to use
the index of the interface to determine whether an interface is still
available or not - in the case of macvtap the thread needs to listen for
traffic on the physical interface, thus having to time out periodically
to check whether the VM's macvtap device is still there as an indication
that the VM is still alive. Previously the following sequence of 2 VMs
with macvtap device
virsh start testvm1; virsh destroy testvm1 ; virsh start testvm2
would not terminate the thread upon testvm1's destroy since the name of
the interface on the host could be the same (i.e, macvtap0) on testvm1
and testvm2, thus it was easily race-able. The thread would then
determine the IP address parameter for testvm2 but apply the rule set
for testvm1. :-(
I am also introducing a lock for the interface (by name) that the thread
must hold while it listens for the traffic and releases when it
terminates upon VM termination or 0.5 second thereafter. Thus, the new
thread for a newly started VM with the same interface name will not
start while the old one still holds the lock. The only other code that I
see that also needs to grab the lock to serialize operation is the one
that tears down the firewall that were established on behalf of an
interface.
I am moving the code applying the 'basic' firewall rules during the IP
address learning phase inside the thread but won't start the thread
unless it is ensured that the firewall driver has the ability to apply
the 'basic' firewall rules.
I am moving some of the eb/iptables related functions into the interface
of the firewall driver and am making them only accessible via the driver's
interface. Otherwise exsiting code is adapted where needed. I am adding one
new function to the interface that checks whether the 'basic' rules can be
applied, which will then be used by a subsequent patch.
I am getting rid of determining the path to necessary CLI tools at
compile time. Instead, now the firewall driver has an initialization
function that uses virFindFileInPath() to determine the path to
necessary CLI tools and a shutdown function to free allocated memory.
The rest of the patch mostly deals with availability of the CLI tools
and to not call certain code blocks if a tool is not available and that
strings now have to be built slightly differently.
Changes from v1 to v2:
- changed function name prefixes to 'iface' from previous 'Iface'
- Further to make make syntax-check pass:
- indentation fix in interface.h
- added entry to POTFILES.in
I am consolidating network interface related functions used in nwfilter
and macvtap code in utils/interface.c. All function names are prefixed
with 'Iface'. The following functions are now available through
interface.h:
int ifaceCtrl(const char *name, bool up);
int ifaceUp(const char *name);
int ifaceDown(const char *name);
int ifaceCheck(bool reportError, const char *ifname,
const unsigned char *macaddr, int ifindex);
int ifaceGetIndex(bool reportError, const char *ifname, int *ifindex);
I added 'int ifindex' as parameter to ifaceCheck to the original
function and modified the code accordingly.
This patch implements support for learning a VM's IP address. It uses
the pcap library to listen on the VM's backend network interface (tap)
or the physical ethernet device (macvtap) and tries to capture packets
with source or destination MAC address of the VM and learn from DHCP
Offers, ARP traffic, or first-sent IPv4 packet what the IP address of
the VM's interface is. This then allows to instantiate the network
traffic filtering rules without the user having to provide the IP
parameter somewhere in the filter description or in the interface
description as a parameter. This only supports to detect the parameter
IP, which is for the assumed single IPv4 address of a VM. There is not
support for interfaces that may have multiple IP addresses (IP
aliasing) or IPv6 that may then require more than one valid IP address
to be detected. A VM can have multiple independent interfaces that each
uses a different IP address and in that case it will be attempted to
detect each one of the address independently.
So, when for example an interface description in the domain XML has
looked like this up to now:
<interface type='bridge'>
<source bridge='mybridge'/>
<model type='virtio'/>
<filterref filter='clean-traffic'>
<parameter name='IP' value='10.2.3.4'/>
</filterref>
</interface>
you may omit the IP parameter:
<interface type='bridge'>
<source bridge='mybridge'/>
<model type='virtio'/>
<filterref filter='clean-traffic'/>
</interface>
Internally I am walking the 'tree' of a VM's referenced network filters
and determine with the given variables which variables are missing. Now,
the above IP parameter may be missing and this causes a libvirt-internal
thread to be started that uses the pcap library's API to listen to the
backend interface (in case of macvtap to the physical interface) in an
attempt to determine the missing IP parameter. If the backend interface
disappears the thread terminates assuming the VM was brought down. In
case of a macvtap device a timeout is being used to wait for packets
from the given VM (filtering by VM's interface MAC address). If the VM's
macvtap device disappeared the thread also terminates. In all other
cases it tries to determine the IP address of the VM and will then apply
the rules late on the given interface, which would have happened
immediately if the IP parameter had been explicitly given. In case an
error happens while the firewall rules are applied, the VM's backend
interface is 'down'ed preventing it to communicate. Reasons for failure
for applying the network firewall rules may that an ebtables/iptables
command failes or OOM errors. Essentially the same failure reasons may
occur as when the firewall rules are applied immediately on VM start,
except that due to the late application of the filtering rules the VM
now is already running and cannot be hindered anymore from starting.
Bringing down the whole VM would probably be considered too drastic.
While a VM's IP address is attempted to be determined only limited
updates to network filters are allowed. In particular it is prevented
that filters are modified in such a way that they would introduce new
variables.
A caveat: The algorithm does not know which one is the appropriate IP
address of a VM. If the VM spoofs an IP address in its first ARP traffic
or IPv4 packets its filtering rules will be instantiated for this IP
address, thus 'locking' it to the found IP address. So, it's still
'safer' to explicitly provide the IP address of a VM's interface in the
filter description if it is known beforehand.
* configure.ac: detect libpcap
* libvirt.spec.in: require libpcap[-devel] if qemu is built
* src/internal.h: add the new ATTRIBUTE_PACKED define
* src/Makefile.am src/libvirt_private.syms: add the new modules and symbols
* src/nwfilter/nwfilter_learnipaddr.[ch]: new module being added
* src/nwfilter/nwfilter_driver.c src/conf/nwfilter_conf.[ch]
src/nwfilter/nwfilter_ebiptables_driver.[ch]
src/nwfilter/nwfilter_gentech_driver.[ch]: plu the new functionality in
* tests/nwfilterxml2xmltest: extend testing
This patch removes the driver dependency from nwfilter_conf.c and moves
a callback function calling into the driver into
nwfilter_gentech_driver.c and passes a pointer to that callback function
upon initialization of nwfilter_conf.c.
This patch implements the core driver and provides
- management functionality for managing the filter XMLs
- compiling the internal filter representation into ebtables rules
- applying ebtables rules on a network (tap,macvtap) interface
- tearing down ebtables rules that were applied on behalf of an
interface
- updating of filters while VMs are running and causing the firewalls to
be rebuilt
- other bits and pieces
Signed-off-by: Stefan Berger <stefanb@us.ibm.com>
