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2020-11-11Teach netstack how to add options to IPv4 packetsJulian Elischer
Most packets don't have options but they are an integral part of the standard. Teaching the ipv4 code how to handle them will simplify future testing and use. Because Options are so rare it is worth making sure that the extra work is kept out of the fast path as much as possible. Prior to this change, all usages of the IHL field of the IPv4Fields/Encode system set it to the same constant value except in a couple of tests for bad values. From this change IHL will not be a constant as it will depend on the size of any Options. Since ipv4.Encode() now handles the options it becomes a possible source of errors to let the callers set this value, so remove it entirely and calculate the value from the size of the Options if present (or not) therefore guaranteeing a correct value. Fixes #4709 RELNOTES: n/a PiperOrigin-RevId: 341864765
2020-11-09Skip `EventHUp` notify in `FIN_WAIT2` on a socket close.Mithun Iyer
This Notify was added as part of cl/279106406; but notifying `EventHUp` in `FIN_WAIT2` is incorrect, as we want to only notify later on `TIME_WAIT` or a reset. However, we do need to notify any blocked waiters of an activity on the endpoint with `EventIn`|`EventOut`. PiperOrigin-RevId: 341490913
2020-11-09net: connect to the ipv4 localhost returns ENETUNREACH if the address isn't setAndrei Vagin
cl/340002915 modified the code to return EADDRNOTAVAIL if connect is called for a localhost address which isn't set. But actually, Linux returns EADDRNOTAVAIL for ipv6 addresses and ENETUNREACH for ipv4 addresses. Updates #4735 PiperOrigin-RevId: 341479129
2020-11-09Initialize references with a value of 1.Dean Deng
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
2020-11-06Trim link headers from buffer clone when sniffingGhanan Gowripalan
PiperOrigin-RevId: 341135083
2020-11-06Return early in walkSACK if segment has no SACK blocks.Bhasker Hariharan
This avoids a needless allocation. Updates #231 PiperOrigin-RevId: 341113160
2020-11-06Do not send to the zero portGhanan Gowripalan
Port 0 is not meant to identify any remote port so attempting to send a packet to it should return an error. PiperOrigin-RevId: 341009528
2020-11-05Cache addressEndpoint.addr.Subnet() to avoid allocations.Bhasker Hariharan
This change adds a Subnet() method to AddressableEndpoint so that we can avoid repeated calls to AddressableEndpoint.AddressWithPrefix().Subnet(). Updates #231 PiperOrigin-RevId: 340969877
2020-11-05Use stack.Route exclusively for writing packetsGhanan Gowripalan
* Remove stack.Route from incoming packet path. There is no need to pass around a stack.Route during the incoming path of a packet. Instead, pass around the packet's link/network layer information in the packet buffer since all layers may need this information. * Support address bound and outgoing packet NIC in routes. When forwarding is enabled, the source address of a packet may be bound to a different interface than the outgoing interface. This change updates stack.Route to hold both NICs so that one can be used to write packets while the other is used to check if the route's bound address is valid. Note, we need to hold the address's interface so we can check if the address is a spoofed address. * Introduce the concept of a local route. Local routes are routes where the packet never needs to leave the stack; the destination is stack-local. We can now route between interfaces within a stack if the packet never needs to leave the stack, even when forwarding is disabled. * Always obtain a route from the stack before sending a packet. If a packet needs to be sent in response to an incoming packet, a route must be obtained from the stack to ensure the stack is configured to send packets to the packet's source from the packet's destination. * Enable spoofing if a stack may send packets from unowned addresses. This change required changes to some netgophers since previously, promiscuous mode was enough to let the netstack respond to all incoming packets regardless of the packet's destination address. Now that a stack.Route is not held for each incoming packet, finding a route may fail with local addresses we don't own but accepted packets for while in promiscuous mode. Since we also want to be able to send from any address (in response the received promiscuous mode packets), we need to enable spoofing. * Skip transport layer checksum checks for locally generated packets. If a packet is locally generated, the stack can safely assume that no errors were introduced while being locally routed since the packet is never sent out the wire. Some bugs fixed: - transport layer checksum was never calculated after NAT. - handleLocal didn't handle routing across interfaces. - stack didn't support forwarding across interfaces. - always consult the routing table before creating an endpoint. Updates #4688 Fixes #3906 PiperOrigin-RevId: 340943442
2020-11-04Unlock tcp endpoint mutex before blocking forever.Dean Deng
This was occasionally causing tests to get stuck due to races with the save process, during which the same mutex is acquired. PiperOrigin-RevId: 340789616
2020-11-03Release mutex before blocking during TCP handshake route resolution.Dean Deng
Without releasing the mutex, operations on the endpoint following a nonblocking connect will not make progress until connect is complete. PiperOrigin-RevId: 340467654
2020-11-02Send NUD probes in a separate gorountineSam Balana
Send NUD probes in another gorountine to free the thread of execution for finishing the state transition. This is necessary to avoid deadlock where sending and processing probes are done in the same call stack, such as loopback and integration tests. Fixes #4701 PiperOrigin-RevId: 340362481
2020-11-02Automated rollback of changelist 339945377Dean Deng
PiperOrigin-RevId: 340274194
2020-10-31net/tcpip: connect to unset loopback address has to return EADDRNOTAVAILAndrei Vagin
In the docker container, the ipv6 loopback address is not set, and connect("::1") has to return ENEADDRNOTAVAIL in this case. Without this fix, it returns EHOSTUNREACH. PiperOrigin-RevId: 340002915
2020-10-30Automated rollback of changelist 339750876Dean Deng
PiperOrigin-RevId: 339945377
2020-10-29Automated rollback of changelist 339675182Dean Deng
PiperOrigin-RevId: 339750876
2020-10-29Make RedirectTarget thread safeKevin Krakauer
Fixes #4613. PiperOrigin-RevId: 339746784
2020-10-29Fix TCP wildcard bind failure when netstack is v6 onlyTing-Yu Wang
TCP endpoint unconditionly binds to v4 even when the stack only supports v6. PiperOrigin-RevId: 339739392
2020-10-29Keep magic constants out of netstackKevin Krakauer
PiperOrigin-RevId: 339721152
2020-10-29Delay goroutine creation during TCP handshake for accept/connect.Dean Deng
Refactor TCP handshake code so that when connect is initiated, the initial SYN is sent before creating a goroutine to handle the rest of the handshake (which blocks). Similarly, the initial SYN-ACK is sent inline when SYN is received during accept. Some additional cleanup is done as well. Eventually we would like to complete connections in the dispatcher without requiring a wakeup to complete the handshake. This refactor makes that easier. Updates #231 PiperOrigin-RevId: 339675182
2020-10-28Avoid time.Now in NUDTamir Duberstein
Use the stack clock instead. Change NeighborEntry.UpdatedAt to UpdatedAtNanos. PiperOrigin-RevId: 339520566
2020-10-27Add support for Timestamp and RecordRoute IP optionsJulian Elischer
IPv4 options extend the size of the IP header and have a basic known format. The framework can process that format without needing to know about every possible option. We can add more code to handle additional option types as we need them. Bad options or mangled option entries can result in ICMP Parameter Problem packets. The first types we support are the Timestamp option and the Record Route option, included in this change. The options are processed at several points in the packet flow within the Network stack, with slightly different requirements. The framework includes a mechanism to control this at each point. Support has been added for such points which are only present in upcoming CLs such as during packet forwarding and fragmentation. With this change, 'ping -R' and 'ping -T' work against gVisor and Fuchsia. $ ping -R 192.168.1.2 PING 192.168.1.2 (192.168.1.2) 56(124) bytes of data. 64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.990 ms NOP RR: 192.168.1.1 192.168.1.2 192.168.1.1 $ ping -T tsprespec 192.168.1.2 192.168.1.1 192.168.1.2 PING 192.168.1.2 (192.168.1.2) 56(124) bytes of data. 64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=1.20 ms TS: 192.168.1.2 71486821 absolute 192.168.1.1 746 Unit tests included for generic options, Timestamp options and Record Route options. PiperOrigin-RevId: 339379076
2020-10-27Wake up any waiters on an ICMP error on UDP socket.Bhasker Hariharan
This change wakes up any waiters when we receive an ICMP port unreachable control packet on an UDP socket as well as sets waiter.EventErr in the result returned by Readiness() when e.lastError is not nil. The latter is required where an epoll()/poll() is done after the error is already handled since we will never notify again in such cases. PiperOrigin-RevId: 339370469
2020-10-27Pass NeighborEntry in NUD callbacksTamir Duberstein
...instead of passing its fields piecemeal. PiperOrigin-RevId: 339345899
2020-10-27Add basic address deletion to netlinkIan Lewis
Updates #3921 PiperOrigin-RevId: 339195417
2020-10-24Send ICMP error message if IP fragment reassembly failsToshi Kikuchi
Fixes #4427, #4428 PiperOrigin-RevId: 338805047
2020-10-23Wait before transitioning NUD entries from Probe to FailedSam Balana
Wait an additional RetransmitTimer duration after the last probe before transitioning to Failed. The previous implementation transitions immediately to Failed after sending the last probe, which is erroneous behavior. PiperOrigin-RevId: 338723794
2020-10-23Fix TestTCPTimeWaitNewSyn.Bhasker Hariharan
Drain the notification channel after first accept as in case the first accept never blocked then the notification for the first accept will still be in the channel causing the second accept to fail as it will try to wait on the channel and return immediately due to the older notification even though there is no connection yet in the accept queue. PiperOrigin-RevId: 338710062
2020-10-23Support getsockopt for SO_ACCEPTCONN.Nayana Bidari
The SO_ACCEPTCONN option is used only on getsockopt(). When this option is specified, getsockopt() indicates whether socket listening is enabled for the socket. A value of zero indicates that socket listening is disabled; non-zero that it is enabled. PiperOrigin-RevId: 338703206
2020-10-23Do not hold NIC local address in neighbor entriesGhanan Gowripalan
Previously, the NIC local address used when completing link resolution was held in the neighbor entry. A neighbor is not identified by any NIC local address so remove it. PiperOrigin-RevId: 338699695
2020-10-23Decrement e.synRcvdCount once handshake is complete.Bhasker Hariharan
Earlier the count was dropped only after calling e.deliverAccepted. This lead to an issue where there were no connections in SYN-RCVD state for the listening endpoint but e.synRcvdCount would not be zero because it was being reduced only when handleSynSegment returned after deliverAccepted returned. This issue is seen when the Nth SYN for a listen backlog of size N which would cause the listen backlog to be full gets dropped occasionally. This happens when the new SYN comes at when the previous completed endpoint has been delivered to the accept queue but the synRcvdCount hasn't yet been decremented because the goroutine running handleSynSegment has not yet completed. PiperOrigin-RevId: 338690646
2020-10-23Rewrite reference leak checker without finalizers.Dean Deng
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
2020-10-22Pass NetworkInterface to LinkAddressRequestGhanan Gowripalan
Previously a link endpoint was passed to stack.LinkAddressResolver.LinkAddressRequest. With this change, implementations that want a route for the link address request may find one through the stack. Other implementations that want to send a packet without a route may continue to do so using the network interface directly. Test: - arp_test.TestLinkAddressRequest - ipv6.TestLinkAddressRequest PiperOrigin-RevId: 338577474
2020-10-21Add underflow check when calculating the MTUArthur Sfez
Also enforce the minimum MTU for IPv4 and IPv6, and discard packets if the minimum is not met. PiperOrigin-RevId: 338404225
2020-10-20Fix nogo test in //pkg/tcpip/...Ting-Yu Wang
PiperOrigin-RevId: 338168977
2020-10-20Fix locking in AddressableEndpointStateGhanan Gowripalan
PiperOrigin-RevId: 338156438
2020-10-20Fix nogo tests.Ting-Yu Wang
//pkg/tcpip/stack:stack_x_test_nogo //pkg/tcpip/transport/raw:raw_nogo PiperOrigin-RevId: 338153265
2020-10-16Don't include link header when forwarding packetsGhanan Gowripalan
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
2020-10-16Make IPv4 check the IP header checksumJulian Elischer
The IPv4 header checksum has not been checked, at least in recent times, so add code to do so. Fix all the tests that fail because they never needed to set the checksum. Fixes #4484 PiperOrigin-RevId: 337556243
2020-10-16Enable IPv4 fragmentation for every code path.Arthur Sfez
Currently, fragmentation can only occur during WritePacket(). This enables it for WritePackets() and WriteIncludedHeaderPacket() as well. IPv4 unit tests were refactored to be consistent with the IPv6 unit tests. This removes the extraHeaderReserveLength field and the related "prependable bytes" unit tests (for both IPv4 and IPv6) because it was only testing a panic condition when the value was too low. Fixes #3796 PiperOrigin-RevId: 337550061
2020-10-16Enable IPv6 WriteHeaderIncludedPacketGhanan Gowripalan
Allow writing an IPv6 packet where the IPv6 header is a provided by the user. * Introduce an error to let callers know a header is malformed. We previously useed tcpip.ErrInvalidOptionValue but that did not seem appropriate for generic malformed header errors. * Populate network header in WriteHeaderIncludedPacket IPv4's implementation of WriteHeaderIncludedPacket did not previously populate the packet buffer's network header. This change fixes that. Fixes #4527 Test: ip_test.TestWriteHeaderIncludedPacket PiperOrigin-RevId: 337534548
2020-10-15Process NAs without target link-layer addressesSam Balana
RFC 4861 section 4.4 comments the Target link-layer address option is sometimes optional in a Neighbor Advertisement packet: "When responding to a unicast Neighbor Solicitation this option SHOULD be included." Tests: pkg/tcpip/stack:stack_test - TestEntryStaleToReachableWhenSolicitedConfirmationWithoutAddress - TestEntryDelayToReachableWhenSolicitedConfirmationWithoutAddress - TestEntryProbeToReachableWhenSolicitedConfirmationWithoutAddress pkg/tcpip/network/ipv6:ipv6_test - TestCallsToNeighborCache PiperOrigin-RevId: 337396493
2020-10-15Refactor compareFragments to follow Go styleArthur Sfez
Test helpers should be used for test setup/teardown, not actual testing. Use cmp.Diff instead of bytes.Equal to improve readability. PiperOrigin-RevId: 337323242
2020-10-14Find route before sending NA responseGhanan Gowripalan
This change also brings back the stack.Route.ResolveWith method so that we can immediately resolve a route when sending an NA in response to a a NS with a source link layer address option. Test: ipv6_test.TestNeighorSolicitationResponse PiperOrigin-RevId: 337185461
2020-10-13Merge pull request #4486 from patr0nus:master_udp_ep_fixgVisor bot
PiperOrigin-RevId: 336974095
2020-10-13Correct NA minimum sizeSam Balana
Remove the duplicate NA size variable while I'm here. See https://tools.ietf.org/html/rfc4861#section-4.4 for the packet format. PiperOrigin-RevId: 336943206
2020-10-13Use NDP option serializer instead of handcrafting the NSTamir Duberstein
Use the correct constant (Solicit, not Advert) while I'm here. PiperOrigin-RevId: 336924605
2020-10-11Assign ep.effectiveNetProtos in UDP forwarder's CreateEndpointpatr0nus
2020-10-09TCP Receive window advertisement fixes.Bhasker Hariharan
The fix in commit 028e045da93b7c1c26417e80e4b4e388b86a713d was incorrect as it can cause the right edge of the window to shrink when we announce a zero window due to receive buffer being full as its done before the check for seeing if the window is being shrunk because of the selected window. Further the window was calculated purely on available space but in cases where we are getting full sized segments it makes more sense to use the actual bytes being held. This CL changes to use the lower of the total available space vs the available space in the maximal window we could advertise minus the actual payload bytes being held. This change also cleans up the code so that the window selection logic is not duplicated between getSendParams() and windowCrossedACKThresholdLocked. PiperOrigin-RevId: 336404827
2020-10-09RACK: Detect packet reordering.Nayana Bidari
RACK detects packet reordering by checking if the sender received ACK for the packet which has the sequence number less than the already acknowledged packets. PiperOrigin-RevId: 336397526