Use the previously introduced chain priorities to sort the chains for access
from an interface's 'root' table and have them created in the proper order.
This gets rid of a lot of code that was previously creating the chains in a
more hardcoded way.
To determine what protocol a filter is used for evaluation do prefix-
matching, i.e., the filter 'arp' is used to filter for the 'arp' protocol,
'ipv4' for the 'ipv4' protocol and 'arp-xyz' will also be used to filter
for the 'arp' protocol following the prefix 'arp' in its name.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
For better handling of the sorting of chains introduce an internally used
priority. Use a lookup table to store the priorities. For now their actual
values do not matter just that the values cause the chains to be properly
sorted through changes in the following patches. However, the values are
chosen as negative so that once they are sorted along with filtering rules
(whose priority may only be positive for now) they will always be instantiated
before them (lower values cause instantiation before higher values). This
is done to maintain backwards compatibility.
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
It's not worth even worrying about a temporary file, unless we
ever expect the script to exceed maximum command-line argument
length limits.
* src/nwfilter/nwfilter_ebiptables_driver.c (ebiptablesExecCLI):
Run the commands as an argument to /bin/sh, rather than worrying
about a temporary file.
(ebiptablesWriteToTempFile): Delete unused function.
If /tmp is mounted with the noexec flag (common on security-conscious
systems), then nwfilter will fail to initialize, because we cannot
run any temporary script via virRun("/tmp/script"); but we _can_
use "/bin/sh /tmp/script". For that matter, using /tmp risks collisions
with other unrelated programs; we already have /var/run/libvirt as a
dedicated temporary directory for use by libvirt.
* src/nwfilter/nwfilter_ebiptables_driver.c
(ebiptablesWriteToTempFile): Use internal directory, not /tmp;
drop attempts to make script executable; and detect close error.
(ebiptablesExecCLI): Switch to virCommand, and invoke the shell to
read the script, rather than requiring an executable script.
The socket address APIs in src/util/network.h either take the
form virSocketAddrXXX, virSocketXXX or virSocketXXXAddr.
Sanitize this so everything is virSocketAddrXXXX, and ensure
that the virSocketAddr parameter is always the first one.
* src/util/network.c, src/util/network.h: Santize socket
address API naming
* src/conf/domain_conf.c, src/conf/network_conf.c,
src/conf/nwfilter_conf.c, src/network/bridge_driver.c,
src/nwfilter/nwfilter_ebiptables_driver.c,
src/nwfilter/nwfilter_learnipaddr.c,
src/qemu/qemu_command.c, src/rpc/virnetsocket.c,
src/util/dnsmasq.c, src/util/iptables.c,
src/util/virnetdev.c, src/vbox/vbox_tmpl.c: Update for
API renaming
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.
Done as a separate commit to make backporting the next patch easier.
We are already using "intprops.h", but this makes it explicit.
* .gnulib: Update, for syntax-check fix.
* bootstrap.conf (gnulib_modules): Make intprops use explicit.
* src/locking/domain_lock.c (includes): Drop unused header.
* src/nwfilter/nwfilter_learnipaddr.c (includes): Use "", not <>,
for gnulib.
Seems reasonable to have all command wrappers in the same place
v2:
Dont move SetInherit
v3:
Comment spelling fix
Adjust WARN0 comment
Remove spurious #include movement
Don't include sys/types.h
Combine virExec enums
Signed-off-by: Cole Robinson <crobinso@redhat.com>
This patch reorders the locks for the nwfilter updates and the access
the nwfilter objects. In the case that the IP address learning thread
was instantiating filters while an update happened, the previous order
lead to a deadlock.
In most cases this affects flags parameters that are unsigned in the
public and driver API but signed in the XDR protocol. Switch the
XDR protocol to unsigned for those.
A counterexample is virNWFilterGetXMLDesc. Its flags parameter is signed
in the public API and XDR protocol, but unsigned in the driver API.
This patch enables filtering of gratuitous ARP packets using the following XML:
<rule action='accept' direction='in' priority='425'>
<arp gratuitous='true'/>
</rule>
The public API and RPC over-the-wire format have no flags argument,
so neither should the internal callback API. This simplifies the
RPC generator.
* src/driver.h (virDrvNWFilterDefineXML): Drop argument that does
not match public API.
* src/nwfilter/nwfilter_driver.c (nwfilterDefine): Likewise.
* src/libvirt.c (virNWFilterDefineXML): Likewise.
* daemon/remote_generator.pl: Drop special case.
These VIR_XXXX0 APIs make us confused, use the non-0-suffix APIs instead.
How do these coversions works? The magic is using the gcc extension of ##.
When __VA_ARGS__ is empty, "##" will swallow the "," in "fmt," to
avoid compile error.
example: origin after CPP
high_level_api("%d", a_int) low_level_api("%d", a_int)
high_level_api("a string") low_level_api("a string")
About 400 conversions.
8 special conversions:
VIR_XXXX0("") -> VIR_XXXX("msg") (avoid empty format) 2 conversions
VIR_XXXX0(string_literal_with_%) -> VIR_XXXX(%->%%) 0 conversions
VIR_XXXX0(non_string_literal) -> VIR_XXXX("%s", non_string_literal)
(for security) 6 conversions
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This matches the public API and helps to get rid of some special
case code in the remote generator.
Rename driver API functions and XDR protocol structs.
No functional change included outside of the remote generator.
We already have virAsprintf, so picking a similar name helps for
seeing a similar purpose. Furthermore, the prefix V before printf
generally implies 'va_list', even though this variant was '...', and
the old name got in the way of adding a new va_list version.
global rename performed with:
$ git grep -l virBufferVSprintf \
| xargs -L1 sed -i 's/virBufferVSprintf/virBufferAsprintf/g'
then revert the changes in ChangeLog-old.
Call shutdown functions for all subcomponents in nwfilterDriverShutdown.
Make sure that this shutdown functions can safely be called multiple times
and independent from the actual subcomponents state.
gcc 4.6 warns when a variable is initialized but isn't used afterwards:
vmware/vmware_driver.c:449:18: warning: variable 'vmxPath' set but not used [-Wunused-but-set-variable]
This patch fixes these warnings. There are still 2 offending files:
- vbox_tmpl.c: the variable is used inside an #ifdef and is assigned several
times outside of #ifdef. Fixing the warning would have required wrapping
all the assignment inside #ifdef which hurts readability.
vbox/vbox_tmpl.c: In function 'vboxAttachDrives':
vbox/vbox_tmpl.c:3918:22: warning: variable 'accessMode' set but not used [-Wunused-but-set-variable]
- esx_vi_types.generated.c: the name implies it's generated code and I
didn't want to dive into the code generator
esx/esx_vi_types.generated.c: In function 'esxVI_FileQueryFlags_Free':
esx/esx_vi_types.generated.c:1203:3: warning: variable 'item' set but not used [-Wunused-but-set-variable]
This patch adds support for the evaluation of TCP flags in nwfilters.
It adds documentation to the web page and extends the tests as well.
Also, the nwfilter schema is extended.
The following are some example for rules using the tcp flags:
<rule action='accept' direction='in'>
<tcp state='NONE' flags='SYN/ALL' dsptportstart='80'/>
</rule>
<rule action='drop' direction='in'>
<tcp state='NONE' flags='SYN/ALL'/>
</rule>
Child processes don't always reach _exit(); if they die from a
signal, then any messages should still be accurate. Most users
either expect a 0 status (thankfully, if status==0, then
WIFEXITED(status) is true and WEXITSTATUS(status)==0 for all
known platforms) or were filtering on WIFEXITED before printing
a status, but a few were missing this check. Additionally,
nwfilter_ebiptables_driver was making an assumption that works
on Linux (where WEXITSTATUS shifts and WTERMSIG just masks)
but fails on other platforms (where WEXITSTATUS just masks and
WTERMSIG shifts).
* src/util/command.h (virCommandTranslateStatus): New helper.
* src/libvirt_private.syms (command.h): Export it.
* src/util/command.c (virCommandTranslateStatus): New function.
(virCommandWait): Use it to also diagnose status from signals.
* src/security/security_apparmor.c (load_profile): Likewise.
* src/storage/storage_backend.c
(virStorageBackendQEMUImgBackingFormat): Likewise.
* src/util/util.c (virExecDaemonize, virRunWithHook)
(virFileOperation, virDirCreate): Likewise.
* daemon/remote.c (remoteDispatchAuthPolkit): Likewise.
* src/nwfilter/nwfilter_ebiptables_driver.c (ebiptablesExecCLI):
Likewise.
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
Since the deallocator is passed into the constructor of
a hash table it is not desirable to pass it into each
function again. Remove it from all functions, but provide
a virHashSteal to allow a item to be removed from a hash
table without deleteing it.
* src/util/hash.c, src/util/hash.h: Remove deallocator
param from all functions. Add virHashSteal
* src/libvirt_private.syms: Add virHashSteal
* src/conf/domain_conf.c, src/conf/nwfilter_params.c,
src/nwfilter/nwfilter_learnipaddr.c,
src/qemu/qemu_command.c, src/xen/xm_internal.c: Update
for changed hash API
This patch adds the possibility to not just drop packets, but to also have them rejected where iptables at least sends an ICMP msg back to the originator. On ebtables this again maps into dropping packets since rejecting is not supported.
I am adding 'since 0.8.9' to the docs assuming this will be the next version of libvirt.
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.
This patch reorders the connlimit and comment match extensions relative to the state match (-m state); connlimit being most useful if found after a -m state --state NEW and not before it.
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.
Rather than only cleaning any remaining ebtables rules, also clean those applied to iptables and ip6tables when detecting the IP address of an interface. Previous applied iptables rules may hinder DHCP packets.
* src/nwfilter/nwfilter_ebiptables_driver.c
(ebiptablesWriteToTempFile): Use /bin/sh.
(bash_cmd_path): Delete.
(ebiptablesDriverInit, ebiptablesDriverShutdown): No need to
search for bash.
(CMD_EXEC): Prefer $() over ``, since we can assume POSIX.
(iptablesSetupVirtInPost): Use portable 'test' syntax.
(iptablesLinkIPTablesBaseChain): Use POSIX $(()) syntax.
Using automated replacement with sed and editing I have now replaced all
occurrences of close() with VIR_(FORCE_)CLOSE() except for one, of
course. Some replacements were straight forward, others I needed to pay
attention. I hope I payed attention in all the right places... Please
have a look. This should have at least solved one more double-close
error.
The inet_pton and inet_ntop functions are obsolete, replaced
by getaddrinfo+getnameinfo with the AI_NUMERICHOST flag set.
These can be accessed via the virSocket APIs.
The bridge.c code had methods for fetching the IP address of
a bridge which used inet_ntop. Aside from the use of inet_ntop
these methods are broken, because a NIC can have multiple
addresses and this only returns one address. Since the methods
are never used, just remove them.
* src/conf/network_conf.c, src/nwfilter/nwfilter_learnipaddr.c:
Replace inet_pton and inet_ntop with virSocket APIs
* src/util/bridge.c, src/util/bridge.h: Remove unused methods
which called inet_ntop.
The getnameinfo() function is more flexible than inet_ntop()
avoiding the need to if/else the code based on socket family.
Also make it support UNIX socket addrs and allow inclusion
of a port (service) address. Finally do proper error reporting
via normal APIs.
* src/conf/domain_conf.c, src/nwfilter/nwfilter_ebiptables_driver.c,
src/qemu/qemu_conf.c: Fix error handling with virSocketFormat
* src/util/network.c: Rewrite virSocketFormat to use getnameinfo
and cope with UNIX socket addrs.
The nwIPAddress was simply a wrapper about virSocketAddr.
Just use the latter directly, removing all the extra field
de-references from code & helper APIs for parsing/formatting.
Also remove all the redundant casts from strong types to
void * and then immediately back to strong types.
* src/conf/nwfilter_conf.h: Remove nwIPAddress
* src/conf/nwfilter_conf.c, src/nwfilter/nwfilter_ebiptables_driver.c:
Update to use virSocketAddr and remove void * casts.
In the table built for traffic coming from the VM going to the host make the following changes:
- don't ACCEPT the packets but do a 'RETURN' and let the host-specific firewall rules in subsequent rules evaluate whether the traffic is allowed to enter
- use the '-m state' in the rules as everywhere else
The following filter transition from a filter allowing incoming TCP connections
<rule action='accept' direction='in' priority='401'>
<tcp/>
</rule>
<rule action='accept' direction='out' priority='500'>
<tcp/>
</rule>
to one that does not allow them
<rule action='drop' direction='in' priority='401'>
<tcp/>
</rule>
<rule action='accept' direction='out' priority='500'>
<tcp/>
</rule>
did previously not cut off existing (ssh) connections but only prevented newly initiated ones. The attached patch allows to cut off existing connections as well, thus enforcing what the filter is showing.
I had only tested with a configuration where the physical interface is connected to the bridge where the filters are applied. This patch now also solves a filtering problem where the physical interface is not connected to the bridge, but the bridge is given an IP address and the host routes between bridge and physical interface. Here the filters drop non-allowed traffic on the outgoing side on the host.
This is from a bug report and conversation on IRC where Soren reported that while a filter update is occurring on one or more VMs (due to a rule having been edited for example), a deadlock can occur when a VM referencing a filter is started.
The problem is caused by the two locking sequences of
qemu driver, qemu domain, filter # for the VM start operation
filter, qemu_driver, qemu_domain # for the filter update operation
that obviously don't lock in the same order. The problem is the 2nd lock sequence. Here the qemu_driver lock is being grabbed in qemu_driver:qemudVMFilterRebuild()
The following solution is based on the idea of trying to re-arrange the 2nd sequence of locks as follows:
qemu_driver, filter, qemu_driver, qemu_domain
and making the qemu driver recursively lockable so that a second lock can occur, this would then lead to the following net-locking sequence
qemu_driver, filter, qemu_domain
where the 2nd qemu_driver lock has been ( logically ) eliminated.
The 2nd part of the idea is that the sequence of locks (filter, qemu_domain) and (qemu_domain, filter) becomes interchangeable if all code paths where filter AND qemu_domain are locked have a preceding qemu_domain lock that basically blocks their concurrent execution
So, the following code paths exist towards qemu_driver:qemudVMFilterRebuild where we now want to put a qemu_driver lock in front of the filter lock.
-> nwfilterUndefine() [ locks the filter ]
-> virNWFilterTestUnassignDef()
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDefine()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDriverReload()
-> virNWFilterPoolLoadAllConfigs()
->virNWFilterPoolObjLoad()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDriverStartup()
-> virNWFilterPoolLoadAllConfigs()
->virNWFilterPoolObjLoad()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
Qemu is not the only driver using the nwfilter driver, but also the UML driver calls into it. Therefore qemuVMFilterRebuild() can be exchanged with umlVMFilterRebuild() along with the driver lock of qemu_driver that can now be a uml_driver. Further, since UML and Qemu domains can be running on the same machine, the triggering of a rebuild of the filter can touch both types of drivers and their domains.
In the patch below I am now extending each nwfilter callback driver with functions for locking and unlocking the (VM) driver (UML, QEMU) and introduce new functions for locking all registered callback drivers and unlocking them. Then I am distributing the lock-all-cbdrivers/unlock-all-cbdrivers call into the above call paths. The last shown callpath starting with nwfilterDriverStart() is problematic since it is initialize before the Qemu and UML drives are and thus a lock in the path would result in a NULL pointer attempted to be locked -- the call to virNWFilterTriggerVMFilterRebuild() is never called, so we never lock either the qemu_driver or the uml_driver in that path. Therefore, only the first 3 paths now receive calls to lock and unlock all callback drivers. Now that the locks are distributed where it matters I can remove the qemu_driver and uml_driver lock from qemudVMFilterRebuild() and umlVMFilterRebuild() and not requiring the recursive locks.
For now I want to put this out as an RFC patch. I have tested it by 'stretching' the critical section after the define/undefine functions each lock the filter so I can (easily) concurrently execute another VM operation (suspend,start). That code is in this patch and if you want you can de-activate it. It seems to work ok and operations are being blocked while the update is being done.
I still also want to verify the other assumption above that locking filter and qemu_domain always has a preceding qemu_driver lock.
In this patch I am extending the rule instantiator to create the state
match according to the state attribute in the XML. Only one iptables
rule in the incoming or outgoing direction will be created for a rule
in direction 'in' or 'out' respectively. A rule in direction 'inout' does
get iptables rules in both directions.
In this patch I am extending the rule instantiator to create the comment
node where supported, which is the case for iptables and ip6tables.
Since commands are written in the format
cmd='iptables ...-m comment --comment \"\" '
certain characters ('`) in the comment need to be escaped to
prevent comments from becoming commands themselves or cause other
forms of (bash) substitutions. I have tested this with various input and in
my tests the input made it straight into the comment. A test case for TCK
will be provided separately that tests this.
This reverses commit 04c3704, which added a define to nwfilter to
allow libvirtd compilation on Mac OS X. Stefan Bergers commit, 2e7294d,
is the proper solution, removing the requirement for nwfilter on non-Linux.
The patch below reports a warning in the log if the generated ip(6)tables rules would not be effective due to the proc filesystem entries
/proc/sys/net/bridge/bridge-nf-call-iptables
/proc/sys/net/bridge/bridge-nf-call-ip6tables
containing a '0'. The warning tells the user what to do. I am rate-limiting the warning message to appear only every 10 seconds.
In this patch I am extending and fixing the nwfilter module's reload support to stop all ongoing threads (for learning IP addresses of interfaces) and rebuild the filtering rules of all interfaces of all VMs when libvirt is started. Now libvirtd rebuilds the filters upon the SIGHUP signal and libvirtd restart.
About the patch: The nwfilter functions require a virConnectPtr. Therefore I am opening a connection in qemudStartup, which later on needs to be closed outside where the driver lock is held since otherwise it ends up in a deadlock due to virConnectClose() trying to lock the driver as well.
I have tested this now for a while with several machines running and needing the IP address learner thread(s). The rebuilding of the firewall rules seems to work fine following libvirtd restart or a SIGHUP. Also the termination of libvirtd worked fine.
When sniffing the network traffic, discard class D and E IP addresses when sniffing traffic. This was a reason why filters were not correctly rebuilt on VMs on the local 192.* network when libvirt was restarted and those VMs did not use a DHCP request to get its IP address.
While testing the SIGHUP handling and reloading of the nwfilter driver, I found that when the filters are rebuilt and mutlipe threads handled the individual interfaces, concurrently running multiple external bash scripts causes strange failures even though the executed ebtables commands are working on different tables for different interfaces. I cannot say for sure where the concurrency problems are caused, but introducing this lock definitely helps.
Following Daniel Berrange's multiple helpful suggestions for improving
this patch and introducing another driver interface, I now wrote the
below patch where the nwfilter driver registers the functions to
instantiate and teardown the nwfilters with a function in
conf/domain_nwfilter.c called virDomainConfNWFilterRegister. Previous
helper functions that were called from qemu_driver.c and qemu_conf.c
were move into conf/domain_nwfilter.h with slight renaming done for
consistency. Those functions now call the function expored by
domain_nwfilter.c, which in turn call the functions of the new driver
interface, if available.
This patch adds an optional XML attribute to a nwfilter rule to give the user control over whether the rule is supposed to be using the iptables state match or not. A rule may now look like shown in the XML below with the statematch attribute either having value '0' or 'false' (case-insensitive).
[...]
<rule action='accept' direction='in' statematch='false'>
<tcp srcmacaddr='1:2:3:4:5:6'
srcipaddr='10.1.2.3' srcipmask='32'
dscp='33'
srcportstart='20' srcportend='21'
dstportstart='100' dstportend='1111'/>
</rule>
[...]
I am also extending the nwfilter schema and add this attribute to a test case.
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.
The functions invoked by the IP address learning thread
that apply some basic filtering rules did not clean up
any previous filtering rules that may still be there
(due to a libvirt restart for example). With the
patch below all the rules are cleaned up first.
Also, I am introducing a function to drop all traffic
in case the IP address learning thread could not apply
the rules.
The local DHCP server on virtbr0 sends DHCP ACK messages when a VM is
started and requests an IP address while the initial DHCP lease on the
VM's MAC address hasn't expired. So, also pick the IP address of the VM
if that type of message is seen.
Thanks to Gerhard Stenzel for providing a test case for this.
Changes from V1 to V2:
- cleanup: replacing DHCP option numbers through constants
This patch adds support for the RARP protocol. This may be needed due to
qemu sending out a RARP packet (at least that's what it seems to want to
do even though the protocol id is wrong) when migration finishes and
we'd need a rule to let the packets pass.
Unfortunately my installation of ebtables does not understand -p RARP
and also seems to otherwise depend on strings in /etc/ethertype
translated to protocol identifiers. Therefore I need to pass -p 0x8035
for RARP. To generally get rid of the dependency of that file I switch
all so far supported protocols to use their protocol identifier in the
-p parameter rather than the string.
I am also extending the schema and added a test case.
changes from v1 to v2:
- added test case into patch
With this patch I want to enable hex number inputs in the filter XML. A
number that was entered as hex is also printed as hex unless a string
representing the meaning can be found.
I am also extending the schema and adding a test case. A problem with
the DSCP value is fixed on the way as well.
Changes from V1 to V2:
- using asHex boolean in all printf type of functions to select the
output format in hex or decimal format
The nwfilterDriverActive() could de-reference a NULL pointer
if it hadn't be started at the point it was called. It was
also not thread safe, since it lacked locking around data
accesses.
* src/nwfilter/nwfilter_driver.c: Fix locking & NULL checks
in nwfilterDriverActive()
- 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.
To avoid race-conditions, the tear down of a filter has to happen before
the tap interface disappears and another tap interface with the same
name can re-appear. This patch tries to fix this. In one place, where
communication with the qemu monitor may fail, I am only tearing the
filters down after knowing that the function did not fail.
I am also moving the tear down functions into an include file for other
drivers to reuse.
* src/nwfilter/nwfilter_ebiptables_driver.c (ebiptablesApplyNewRules):
Don't dereference a NULL or uninitialized pointer when given
an empty list of rules. Add an sa_assert(inst) in each loop to
tell clang that the uses of "inst[i]" are valid.
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.
I mistakenly took the op field in the DHCP message as the DHCP_OFFER
type. Rather than basing the decision to read the VM's IP address on
that field, process the appended DHCP options where option 53 indicates
the actual type of the packet. I am also reading the broadcast address
of the VM, but don't use it so far.
Changes from V1 to V2 of this patch
- I had reversed the logic thinking that icmp type 0 is a echo
request,but it's reply -- needed to reverse the logic
- Found that ebtables takes the --ip-tos argument only as a hex number
This patch enables the skipping of some of the ICMP traffic rules on the
iptables level under certain circumstances so that the following filter
properly enables unidirectional pings:
<filter name='testcase'>
<uuid>d6b1a2af-def6-2898-9f8d-4a74e3c39558</uuid>
<!-- allow incoming ICMP Echo Request -->
<rule action='accept' direction='in' priority='500'>
<icmp type='8'/>
</rule>
<!-- allow outgoing ICMP Echo Reply -->
<rule action='accept' direction='out' priority='500'>
<icmp type='0'/>
</rule>
<!-- drop all other ICMP traffic -->
<rule action='drop' direction='inout' priority='600'>
<icmp/>
</rule>
</filter>
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
The attached patch fixes a problem due to the mac match in iptables only
supporting --mac-source and no --mac-destination, thus it not being
symmetric. Therefore a rule like this one
<rule action='drop' direction='out'>
<all match='no' srcmacaddr='$MAC'/>
</rule>
should only have the MAC match on traffic leaving the VM and not test
for the same source MAC address on traffic that the VM receives.
With Eric Blake's suggestions applied.
The following rule for direction 'in'
<rule direction='in' action='drop'>
<mac srcmacaddr='1:2:3:4:5:6'/>
</rule>
drops all traffic from the given mac address.
The following rule for direction 'out'
<rule direction='out' action='drop'>
<mac dstmacaddr='1:2:3:4:5:6'/>
</rule>
drops all traffic to the given mac address.
The following rule in direction 'inout'
<rule direction='inout' action='drop'>
<mac srcmacaddr='1:2:3:4:5:6'/>
</rule>
now drops all traffic from and to the given MAC address.
So far it would have dropped traffic from the given MAC address
and outgoing traffic with the given source MAC address, which is not useful
since the packets will always have the VM's MAC address as source
MAC address. The attached patch fixes this.
This is the last bug I currently know of and want to fix.
- ebtables requires that some of the command line parameters are passed as hex numbers; so have those attributes call a function that prints 16 and 8 bit integers as hex nunbers.
- ip6tables requires '--icmpv6-type' rather than '--icmp-type'
- ebtables complains about protocol identifiers lower than 0x600, so already discard anything lower than 0x600 in the parser
- make the protocol entry types more readable using a #define for its entries
- continue parsing a filtering rule even if a faulty entry is encountered; return an error value at the end and let the caller decide what to do with the rule's object
- fix an error message
found some cases where the output ended up not looking as expected. So
the following changes are in the patch below:
- if the protocol ID in the MAC header is an integer, just write it into
the datastructure without trying to find a corresponding string for it
and if none is found failing
- when writing the protocol ID as string, simply write it as integer if
no corresponding string can be found
- same changes for arpOpcode parsing and printing
- same changes for protocol ID in an IP packet
- DSCP value needs to be written into the data structure
- IP protocol version number is redundant at this level, so remove it
- parse the protocol ID found inside an IP packet not only as string but
also as uint8
- arrange the display of the src and destination masks to be shown after
the src and destination ip address respectively in the XML
- the existing libvirt IP address parser accepts for example '25' as an
IP address. I want this to be parsed as a CIDR type netmask. So try to
parse it as an integer first (CIDR netmask) and if that doesn't work as
a dotted IP address style netmask.
- instantiation of rules with MAC masks didn't work because they weren't
printed into a buffer, yet.
This patch changes the network filtering code to use libvirt's existing
IPv4 and IPv6 address parsers/printers rather than my self-written ones.
I am introducing a new function in network.c that counts the number of
bits in a netmask and ensures that the given address is indeed a netmask,
return -1 on error or values of 0-32 for IPv4 addresses and 0-128 for
IPv6 addresses. I then based the function checking for valid netmask
on invoking this function.
This patch adds IPv6 filtering support for the following protocols:
- tcp-ipv6
- udp-ipv6
- udplite-ipv6
- esp-ipv6
- ah-ipv6
- sctp-ipv6
- all-ipv6
- icmpv6
Many of the IPv4 data structure could be re-used for IPv6 support.
Since ip6tables also supports pretty much the same command line parameters
as iptables does, also much of the code could be re-used and now
command lines are invoked with the ip(6)tables tool parameter passed
through the functions as a parameter.
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 adds support for L3/L4 filtering using iptables. This adds
support for 'tcp', 'udp', 'icmp', 'igmp', 'sctp' etc. filtering.
As mentioned in the introduction, a .c file provided by this patch
is #include'd into a .c file. This will need work, but should be alright
for review.
Signed-off-by: Stefan Berger <stefanb@us.ibm.com>
This patch adds IPv6 support for the ebtables layer. Since the parser
etc. are all parameterized, it was fairly easy to add this...
Signed-off-by: Stefan Berger <stefanb@us.ibm.com>
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>