diff options
| -rw-r--r-- | pkg/tcpip/network/fragmentation/fragmentation.go | 48 | ||||
| -rw-r--r-- | pkg/tcpip/network/fragmentation/reassembler.go | 12 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 2 | ||||
| -rw-r--r-- | pkg/tcpip/network/ipv6/ipv6.go | 2 |
4 files changed, 46 insertions, 18 deletions
diff --git a/pkg/tcpip/network/fragmentation/fragmentation.go b/pkg/tcpip/network/fragmentation/fragmentation.go index 6a4843f92..e1909fab0 100644 --- a/pkg/tcpip/network/fragmentation/fragmentation.go +++ b/pkg/tcpip/network/fragmentation/fragmentation.go @@ -81,6 +81,8 @@ type Fragmentation struct { size int timeout time.Duration blockSize uint16 + clock tcpip.Clock + releaseJob *tcpip.Job } // NewFragmentation creates a new Fragmentation. @@ -97,7 +99,7 @@ type Fragmentation struct { // reassemblingTimeout specifies the maximum time allowed to reassemble a packet. // Fragments are lazily evicted only when a new a packet with an // already existing fragmentation-id arrives after the timeout. -func NewFragmentation(blockSize uint16, highMemoryLimit, lowMemoryLimit int, reassemblingTimeout time.Duration) *Fragmentation { +func NewFragmentation(blockSize uint16, highMemoryLimit, lowMemoryLimit int, reassemblingTimeout time.Duration, clock tcpip.Clock) *Fragmentation { if lowMemoryLimit >= highMemoryLimit { lowMemoryLimit = highMemoryLimit } @@ -110,13 +112,17 @@ func NewFragmentation(blockSize uint16, highMemoryLimit, lowMemoryLimit int, rea blockSize = minBlockSize } - return &Fragmentation{ + f := &Fragmentation{ reassemblers: make(map[FragmentID]*reassembler), highLimit: highMemoryLimit, lowLimit: lowMemoryLimit, timeout: reassemblingTimeout, blockSize: blockSize, + clock: clock, } + f.releaseJob = tcpip.NewJob(f.clock, &f.mu, f.releaseReassemblersLocked) + + return f } // Process processes an incoming fragment belonging to an ID and returns a @@ -155,15 +161,17 @@ func (f *Fragmentation) Process( f.mu.Lock() r, ok := f.reassemblers[id] - if ok && r.tooOld(f.timeout) { - // This is very likely to be an id-collision or someone performing a slow-rate attack. - f.release(r) - ok = false - } if !ok { - r = newReassembler(id) + r = newReassembler(id, f.clock) f.reassemblers[id] = r + wasEmpty := f.rList.Empty() f.rList.PushFront(r) + if wasEmpty { + // If we have just pushed a first reassembler into an empty list, we + // should kickstart the release job. The release job will keep + // rescheduling itself until the list becomes empty. + f.releaseReassemblersLocked() + } } f.mu.Unlock() @@ -211,3 +219,27 @@ func (f *Fragmentation) release(r *reassembler) { f.size = 0 } } + +// releaseReassemblersLocked releases already-expired reassemblers, then +// schedules the job to call back itself for the remaining reassemblers if +// any. This function must be called with f.mu locked. +func (f *Fragmentation) releaseReassemblersLocked() { + now := f.clock.NowMonotonic() + for { + // The reassembler at the end of the list is the oldest. + r := f.rList.Back() + if r == nil { + // The list is empty. + break + } + elapsed := time.Duration(now-r.creationTime) * time.Nanosecond + if f.timeout > elapsed { + // If the oldest reassembler has not expired, schedule the release + // job so that this function is called back when it has expired. + f.releaseJob.Schedule(f.timeout - elapsed) + break + } + // If the oldest reassembler has already expired, release it. + f.release(r) + } +} diff --git a/pkg/tcpip/network/fragmentation/reassembler.go b/pkg/tcpip/network/fragmentation/reassembler.go index f044867dc..9bb051a30 100644 --- a/pkg/tcpip/network/fragmentation/reassembler.go +++ b/pkg/tcpip/network/fragmentation/reassembler.go @@ -18,9 +18,9 @@ import ( "container/heap" "fmt" "math" - "time" "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/tcpip" "gvisor.dev/gvisor/pkg/tcpip/buffer" ) @@ -40,15 +40,15 @@ type reassembler struct { deleted int heap fragHeap done bool - creationTime time.Time + creationTime int64 } -func newReassembler(id FragmentID) *reassembler { +func newReassembler(id FragmentID, clock tcpip.Clock) *reassembler { r := &reassembler{ id: id, holes: make([]hole, 0, 16), heap: make(fragHeap, 0, 8), - creationTime: time.Now(), + creationTime: clock.NowMonotonic(), } r.holes = append(r.holes, hole{ first: 0, @@ -116,10 +116,6 @@ func (r *reassembler) process(first, last uint16, more bool, proto uint8, vv buf return res, r.proto, true, consumed, nil } -func (r *reassembler) tooOld(timeout time.Duration) bool { - return time.Now().Sub(r.creationTime) > timeout -} - func (r *reassembler) checkDoneOrMark() bool { r.mu.Lock() prev := r.done diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index 7adf0fac3..cf0a76274 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -804,6 +804,6 @@ func NewProtocol(s *stack.Stack) stack.NetworkProtocol { ids: ids, hashIV: hashIV, defaultTTL: DefaultTTL, - fragmentation: fragmentation.NewFragmentation(fragmentblockSize, fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout), + fragmentation: fragmentation.NewFragmentation(fragmentblockSize, fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout, s.Clock()), } } diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go index d1ad7acb7..990e67210 100644 --- a/pkg/tcpip/network/ipv6/ipv6.go +++ b/pkg/tcpip/network/ipv6/ipv6.go @@ -1306,7 +1306,7 @@ func NewProtocolWithOptions(opts Options) stack.NetworkProtocolFactory { return func(s *stack.Stack) stack.NetworkProtocol { p := &protocol{ stack: s, - fragmentation: fragmentation.NewFragmentation(header.IPv6FragmentExtHdrFragmentOffsetBytesPerUnit, fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout), + fragmentation: fragmentation.NewFragmentation(header.IPv6FragmentExtHdrFragmentOffsetBytesPerUnit, fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout, s.Clock()), ndpDisp: opts.NDPDisp, ndpConfigs: opts.NDPConfigs, |