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Before this change, packets were delivered asynchronously to the remote
end of a pipe. This was to avoid a deadlock during link resolution where
the stack would attempt to double-lock a mutex (see removed comments in
the parent commit for details).
As of https://github.com/google/gvisor/commit/4943347137, we do not hold
locks while sending link resolution probes so the deadlock will no
longer occur.
PiperOrigin-RevId: 356066224
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This makes it possible to add data to types that implement tcpip.Error.
ErrBadLinkEndpoint is removed as it is unused.
PiperOrigin-RevId: 354437314
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PiperOrigin-RevId: 353755271
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Test: integration_test.TestWritePacketsLinkResolution
Fixes #4458.
PiperOrigin-RevId: 353108826
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fdbased and qdisc layers expect these fields to already be
populated before being reached.
PiperOrigin-RevId: 353099492
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Test: integration_test.TestGetLinkAddress
PiperOrigin-RevId: 352119404
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stack.Route is used to send network packets and resolve link addresses.
A LinkEndpoint does not need to do either of these and only needs the
route's fields at the time of the packet write request.
Since LinkEndpoints only need the route's fields when writing packets,
pass a stack.RouteInfo instead.
PiperOrigin-RevId: 352108405
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We loop over the list of packets anyways so setting these aren't
expensive.
Now that they are populated only by the link endpoint that uses them,
TCP does not need to.
PiperOrigin-RevId: 352090853
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Whether the variable was found is already returned by syscall.Getenv.
os.Getenv drops this value while os.Lookupenv passes it along.
PiperOrigin-RevId: 351674032
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These are primarily simplification and lint mistakes. However, minor
fixes are also included and tests added where appropriate.
PiperOrigin-RevId: 351425971
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Ethernet frames are usually filtered at the hardware-level so there is
no need to filter the frames in software.
For test purposes, a new link endpoint was introduced to filter frames
based on their destination.
PiperOrigin-RevId: 350422941
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This condition was inverted in 360006d.
PiperOrigin-RevId: 348679088
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Removes the period of time in which subseqeuent traffic to a Failed neighbor
immediately fails with ErrNoLinkAddress. A Failed neighbor is one in which
address resolution fails; or in other words, the neighbor's IP address cannot
be translated to a MAC address.
This means removing the Failed state for linkAddrCache and allowing transitiong
out of Failed into Incomplete for neighborCache. Previously, both caches would
transition entries to Failed after address resolution fails. In this state, any
subsequent traffic requested within an unreachable time would immediately fail
with ErrNoLinkAddress. This does not follow RFC 4861 section 7.3.3:
If address resolution fails, the entry SHOULD be deleted, so that subsequent
traffic to that neighbor invokes the next-hop determination procedure again.
Invoking next-hop determination at this point ensures that alternate default
routers are tried.
The API for getting a link address for a given address, whether through the link
address cache or the neighbor table, is updated to optionally take a callback
which will be called when address resolution completes. This allows `Route` to
handle completing link resolution internally, so callers of (*Route).Resolve
(e.g. endpoints) don’t have to keep track of when it completes and update the
Route accordingly.
This change also removes the wakers from LinkAddressCache, NeighborCache, and
Route in favor of the callbacks, and callers that previously used a waker can
now just pass a callback to (*Route).Resolve that will notify the waker on
resolution completion.
Fixes #4796
Startblock:
has LGTM from sbalana
and then
add reviewer ghanan
PiperOrigin-RevId: 348597478
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fdbased endpoint was enabling fragment reassembly on the host AF_PACKET socket
to ensure that fragments are delivered inorder to the right dispatcher. But this
prevents fragments from being delivered to gvisor at all and makes testing of
gvisor's fragment reassembly code impossible.
The potential impact from this is minimal since IP Fragmentation is not really
that prevelant and in cases where we do get fragments we may deliver the
fragment out of order to the TCP layer as multiple network dispatchers may
process the fragments and deliver a reassembled fragment after the next packet
has been delivered to the TCP endpoint. While not desirable I believe the impact
from this is minimal due to low prevalence of fragmentation.
Also removed PktType and Hatype fields when binding the socket as these are not
used when binding. Its just confusing to have them specified.
See: https://man7.org/linux/man-pages/man7/packet.7.html
"Fields used for binding are
sll_family (should be AF_PACKET), sll_protocol, and sll_ifindex."
Fixes #5055
PiperOrigin-RevId: 346919439
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Currently we rely on the user to take the lock on the endpoint that owns the
route, in order to modify it safely. We can instead move
`Route.RemoteLinkAddress` under `Route`'s mutex, and allow non-locking and
thread-safe access to other fields of `Route`.
PiperOrigin-RevId: 345461586
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Multiple goroutines may use the same stack.Route concurrently so
the stack.Route should make sure that any functions called on it
are thread-safe.
Fixes #4073
PiperOrigin-RevId: 344320491
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Redefine stack.WritePacket into stack.WritePacketToRemote which lets the NIC
decide whether to append link headers.
PiperOrigin-RevId: 343071742
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A prefix associated with a sniffer instance can help debug situations where
more than one NIC (i.e. more than one sniffer) exists.
PiperOrigin-RevId: 342950027
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- Make AddressableEndpoint optional for NetworkEndpoint.
Not all NetworkEndpoints need to support addressing (e.g. ARP), so
AddressableEndpoint should only be implemented for protocols that
support addressing such as IPv4 and IPv6.
With this change, tcpip.ErrNotSupported will be returned by the stack
when attempting to modify addresses on a network endpoint that does
not support addressing.
Now that packets are fully handled at the network layer, and (with this
change) addresses are optional for network endpoints, we no longer need
the workaround for ARP where a fake ARP address was added to each NIC
that performs ARP so that packets would be delivered to the ARP layer.
PiperOrigin-RevId: 342722547
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This lets us avoid treating a value of 0 as one reference. All references
using the refsvfs2 template must call InitRefs() before the reference is
incremented/decremented, or else a panic will occur. Therefore, it should be
pretty easy to identify missing InitRef calls during testing.
Updates #1486.
PiperOrigin-RevId: 341411151
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PiperOrigin-RevId: 341135083
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Our current reference leak checker uses finalizers to verify whether an object
has reached zero references before it is garbage collected. There are multiple
problems with this mechanism, so a rewrite is in order.
With finalizers, there is no way to guarantee that a finalizer will run before
the program exits. When an unreachable object with a finalizer is garbage
collected, its finalizer will be added to a queue and run asynchronously. The
best we can do is run garbage collection upon sandbox exit to make sure that
all finalizers are enqueued.
Furthermore, if there is a chain of finalized objects, e.g. A points to B
points to C, garbage collection needs to run multiple times before all of the
finalizers are enqueued. The first GC run will register the finalizer for A but
not free it. It takes another GC run to free A, at which point B's finalizer
can be registered. As a result, we need to run GC as many times as the length
of the longest such chain to have a somewhat reliable leak checker.
Finally, a cyclical chain of structs pointing to one another will never be
garbage collected if a finalizer is set. This is a well-known issue with Go
finalizers (https://github.com/golang/go/issues/7358). Using leak checking on
filesystem objects that produce cycles will not work and even result in memory
leaks.
The new leak checker stores reference counted objects in a global map when
leak check is enabled and removes them once they are destroyed. At sandbox
exit, any remaining objects in the map are considered as leaked. This provides
a deterministic way of detecting leaks without relying on the complexities of
finalizers and garbage collection.
This approach has several benefits over the former, including:
- Always detects leaks of objects that should be destroyed very close to
sandbox exit. The old checker very rarely detected these leaks, because it
relied on garbage collection to be run in a short window of time.
- Panics if we forgot to enable leak check on a ref-counted object (we will try
to remove it from the map when it is destroyed, but it will never have been
added).
- Can store extra logging information in the map values without adding to the
size of the ref count struct itself. With the size of just an int64, the ref
count object remains compact, meaning frequent operations like IncRef/DecRef
are more cache-efficient.
- Can aggregate leak results in a single report after the sandbox exits.
Instead of having warnings littered in the log, which were
non-deterministically triggered by garbage collection, we can print all
warning messages at once. Note that this could also be a limitation--the
sandbox must exit properly for leaks to be detected.
Some basic benchmarking indicates that this change does not significantly
affect performance when leak checking is enabled, which is understandable
since registering/unregistering is only done once for each filesystem object.
Updates #1486.
PiperOrigin-RevId: 338685972
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PiperOrigin-RevId: 338168977
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Before this change, if a link header was included in an incoming packet
that is forwarded, the packet that gets sent out will take the original
packet and add a link header to it while keeping the old link header.
This would make the sent packet look like:
OUTGOING LINK HDR | INCOMING LINK HDR | NETWORK HDR | ...
Obviously this is incorrect as we should drop the incoming link header
and only include the outgoing link header. This change fixes this bug.
Test: integration_test.TestForwarding
PiperOrigin-RevId: 337571447
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PiperOrigin-RevId: 336339194
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PiperOrigin-RevId: 336304024
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