diff options
Diffstat (limited to 'pkg/tcpip/stack/addressable_endpoint_state.go')
| -rw-r--r-- | pkg/tcpip/stack/addressable_endpoint_state.go | 717 |
1 files changed, 717 insertions, 0 deletions
diff --git a/pkg/tcpip/stack/addressable_endpoint_state.go b/pkg/tcpip/stack/addressable_endpoint_state.go new file mode 100644 index 000000000..270ac4977 --- /dev/null +++ b/pkg/tcpip/stack/addressable_endpoint_state.go @@ -0,0 +1,717 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package stack + +import ( + "fmt" + + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/tcpip" +) + +var _ GroupAddressableEndpoint = (*AddressableEndpointState)(nil) +var _ AddressableEndpoint = (*AddressableEndpointState)(nil) + +// AddressableEndpointState is an implementation of an AddressableEndpoint. +type AddressableEndpointState struct { + networkEndpoint NetworkEndpoint + + // Lock ordering (from outer to inner lock ordering): + // + // AddressableEndpointState.mu + // addressState.mu + mu struct { + sync.RWMutex + + endpoints map[tcpip.Address]*addressState + primary []*addressState + + // groups holds the mapping between group addresses and the number of times + // they have been joined. + groups map[tcpip.Address]uint32 + } +} + +// Init initializes the AddressableEndpointState with networkEndpoint. +// +// Must be called before calling any other function on m. +func (a *AddressableEndpointState) Init(networkEndpoint NetworkEndpoint) { + a.networkEndpoint = networkEndpoint + + a.mu.Lock() + defer a.mu.Unlock() + a.mu.endpoints = make(map[tcpip.Address]*addressState) + a.mu.groups = make(map[tcpip.Address]uint32) +} + +// ReadOnlyAddressableEndpointState provides read-only access to an +// AddressableEndpointState. +type ReadOnlyAddressableEndpointState struct { + inner *AddressableEndpointState +} + +// AddrOrMatching returns an endpoint for the passed address that is consisdered +// bound to the wrapped AddressableEndpointState. +// +// If addr is an exact match with an existing address, that address is returned. +// Otherwise, f is called with each address and the address that f returns true +// for is returned. +// +// Returns nil of no address matches. +func (m ReadOnlyAddressableEndpointState) AddrOrMatching(addr tcpip.Address, spoofingOrPrimiscuous bool, f func(AddressEndpoint) bool) AddressEndpoint { + m.inner.mu.RLock() + defer m.inner.mu.RUnlock() + + if ep, ok := m.inner.mu.endpoints[addr]; ok { + if ep.IsAssigned(spoofingOrPrimiscuous) && ep.IncRef() { + return ep + } + } + + for _, ep := range m.inner.mu.endpoints { + if ep.IsAssigned(spoofingOrPrimiscuous) && f(ep) && ep.IncRef() { + return ep + } + } + + return nil +} + +// Lookup returns the AddressEndpoint for the passed address. +// +// Returns nil if the passed address is not associated with the +// AddressableEndpointState. +func (m ReadOnlyAddressableEndpointState) Lookup(addr tcpip.Address) AddressEndpoint { + m.inner.mu.RLock() + defer m.inner.mu.RUnlock() + + ep, ok := m.inner.mu.endpoints[addr] + if !ok { + return nil + } + return ep +} + +// ForEach calls f for each address pair. +// +// If f returns false, f is no longer be called. +func (m ReadOnlyAddressableEndpointState) ForEach(f func(AddressEndpoint) bool) { + m.inner.mu.RLock() + defer m.inner.mu.RUnlock() + + for _, ep := range m.inner.mu.endpoints { + if !f(ep) { + return + } + } +} + +// ForEachPrimaryEndpoint calls f for each primary address. +// +// If f returns false, f is no longer be called. +func (m ReadOnlyAddressableEndpointState) ForEachPrimaryEndpoint(f func(AddressEndpoint)) { + m.inner.mu.RLock() + defer m.inner.mu.RUnlock() + for _, ep := range m.inner.mu.primary { + f(ep) + } +} + +// ReadOnly returns a readonly reference to a. +func (a *AddressableEndpointState) ReadOnly() ReadOnlyAddressableEndpointState { + return ReadOnlyAddressableEndpointState{inner: a} +} + +func (a *AddressableEndpointState) releaseAddressState(addrState *addressState) { + a.mu.Lock() + defer a.mu.Unlock() + a.releaseAddressStateLocked(addrState) +} + +// releaseAddressState removes addrState from s's address state (primary and endpoints list). +// +// Preconditions: a.mu must be write locked. +func (a *AddressableEndpointState) releaseAddressStateLocked(addrState *addressState) { + oldPrimary := a.mu.primary + for i, s := range a.mu.primary { + if s == addrState { + a.mu.primary = append(a.mu.primary[:i], a.mu.primary[i+1:]...) + oldPrimary[len(oldPrimary)-1] = nil + break + } + } + delete(a.mu.endpoints, addrState.addr.Address) +} + +// AddAndAcquirePermanentAddress implements AddressableEndpoint. +func (a *AddressableEndpointState) AddAndAcquirePermanentAddress(addr tcpip.AddressWithPrefix, peb PrimaryEndpointBehavior, configType AddressConfigType, deprecated bool) (AddressEndpoint, *tcpip.Error) { + a.mu.Lock() + defer a.mu.Unlock() + ep, err := a.addAndAcquireAddressLocked(addr, peb, configType, deprecated, true /* permanent */) + // From https://golang.org/doc/faq#nil_error: + // + // Under the covers, interfaces are implemented as two elements, a type T and + // a value V. + // + // An interface value is nil only if the V and T are both unset, (T=nil, V is + // not set), In particular, a nil interface will always hold a nil type. If we + // store a nil pointer of type *int inside an interface value, the inner type + // will be *int regardless of the value of the pointer: (T=*int, V=nil). Such + // an interface value will therefore be non-nil even when the pointer value V + // inside is nil. + // + // Since addAndAcquireAddressLocked returns a nil value with a non-nil type, + // we need to explicitly return nil below if ep is (a typed) nil. + if ep == nil { + return nil, err + } + return ep, err +} + +// AddAndAcquireTemporaryAddress adds a temporary address. +// +// Returns tcpip.ErrDuplicateAddress if the address exists. +// +// The temporary address's endpoint is acquired and returned. +func (a *AddressableEndpointState) AddAndAcquireTemporaryAddress(addr tcpip.AddressWithPrefix, peb PrimaryEndpointBehavior) (AddressEndpoint, *tcpip.Error) { + a.mu.Lock() + defer a.mu.Unlock() + ep, err := a.addAndAcquireAddressLocked(addr, peb, AddressConfigStatic, false /* deprecated */, false /* permanent */) + // From https://golang.org/doc/faq#nil_error: + // + // Under the covers, interfaces are implemented as two elements, a type T and + // a value V. + // + // An interface value is nil only if the V and T are both unset, (T=nil, V is + // not set), In particular, a nil interface will always hold a nil type. If we + // store a nil pointer of type *int inside an interface value, the inner type + // will be *int regardless of the value of the pointer: (T=*int, V=nil). Such + // an interface value will therefore be non-nil even when the pointer value V + // inside is nil. + // + // Since addAndAcquireAddressLocked returns a nil value with a non-nil type, + // we need to explicitly return nil below if ep is (a typed) nil. + if ep == nil { + return nil, err + } + return ep, err +} + +// addAndAcquireAddressLocked adds, acquires and returns a permanent or +// temporary address. +// +// If the addressable endpoint already has the address in a non-permanent state, +// and addAndAcquireAddressLocked is adding a permanent address, that address is +// promoted in place and its properties set to the properties provided. If the +// address already exists in any other state, then tcpip.ErrDuplicateAddress is +// returned, regardless the kind of address that is being added. +// +// Precondition: a.mu must be write locked. +func (a *AddressableEndpointState) addAndAcquireAddressLocked(addr tcpip.AddressWithPrefix, peb PrimaryEndpointBehavior, configType AddressConfigType, deprecated, permanent bool) (*addressState, *tcpip.Error) { + // attemptAddToPrimary is false when the address is already in the primary + // address list. + attemptAddToPrimary := true + addrState, ok := a.mu.endpoints[addr.Address] + if ok { + if !permanent { + // We are adding a non-permanent address but the address exists. No need + // to go any further since we can only promote existing temporary/expired + // addresses to permanent. + return nil, tcpip.ErrDuplicateAddress + } + + addrState.mu.Lock() + if addrState.mu.kind.IsPermanent() { + addrState.mu.Unlock() + // We are adding a permanent address but a permanent address already + // exists. + return nil, tcpip.ErrDuplicateAddress + } + + if addrState.mu.refs == 0 { + panic(fmt.Sprintf("found an address that should have been released (ref count == 0); address = %s", addrState.addr)) + } + + // We now promote the address. + for i, s := range a.mu.primary { + if s == addrState { + switch peb { + case CanBePrimaryEndpoint: + // The address is already in the primary address list. + attemptAddToPrimary = false + case FirstPrimaryEndpoint: + if i == 0 { + // The address is already first in the primary address list. + attemptAddToPrimary = false + } else { + a.mu.primary = append(a.mu.primary[:i], a.mu.primary[i+1:]...) + } + case NeverPrimaryEndpoint: + a.mu.primary = append(a.mu.primary[:i], a.mu.primary[i+1:]...) + default: + panic(fmt.Sprintf("unrecognized primary endpoint behaviour = %d", peb)) + } + break + } + } + } + + if addrState == nil { + addrState = &addressState{ + addressableEndpointState: a, + addr: addr, + } + a.mu.endpoints[addr.Address] = addrState + addrState.mu.Lock() + // We never promote an address to temporary - it can only be added as such. + // If we are actaully adding a permanent address, it is promoted below. + addrState.mu.kind = Temporary + } + + // At this point we have an address we are either promoting from an expired or + // temporary address to permanent, promoting an expired address to temporary, + // or we are adding a new temporary or permanent address. + // + // The address MUST be write locked at this point. + defer addrState.mu.Unlock() + + if permanent { + if addrState.mu.kind.IsPermanent() { + panic(fmt.Sprintf("only non-permanent addresses should be promoted to permanent; address = %s", addrState.addr)) + } + + // Primary addresses are biased by 1. + addrState.mu.refs++ + addrState.mu.kind = Permanent + } + // Acquire the address before returning it. + addrState.mu.refs++ + addrState.mu.deprecated = deprecated + addrState.mu.configType = configType + + if attemptAddToPrimary { + switch peb { + case NeverPrimaryEndpoint: + case CanBePrimaryEndpoint: + a.mu.primary = append(a.mu.primary, addrState) + case FirstPrimaryEndpoint: + if cap(a.mu.primary) == len(a.mu.primary) { + a.mu.primary = append([]*addressState{addrState}, a.mu.primary...) + } else { + // Shift all the endpoints by 1 to make room for the new address at the + // front. We could have just created a new slice but this saves + // allocations when the slice has capacity for the new address. + primaryCount := len(a.mu.primary) + a.mu.primary = append(a.mu.primary, nil) + if n := copy(a.mu.primary[1:], a.mu.primary); n != primaryCount { + panic(fmt.Sprintf("copied %d elements; expected = %d elements", n, primaryCount)) + } + a.mu.primary[0] = addrState + } + default: + panic(fmt.Sprintf("unrecognized primary endpoint behaviour = %d", peb)) + } + } + + return addrState, nil +} + +// RemovePermanentAddress implements AddressableEndpoint. +func (a *AddressableEndpointState) RemovePermanentAddress(addr tcpip.Address) *tcpip.Error { + a.mu.Lock() + defer a.mu.Unlock() + + if _, ok := a.mu.groups[addr]; ok { + panic(fmt.Sprintf("group address = %s must be removed with LeaveGroup", addr)) + } + + return a.removePermanentAddressLocked(addr) +} + +// removePermanentAddressLocked is like RemovePermanentAddress but with locking +// requirements. +// +// Precondition: a.mu must be write locked. +func (a *AddressableEndpointState) removePermanentAddressLocked(addr tcpip.Address) *tcpip.Error { + addrState, ok := a.mu.endpoints[addr] + if !ok { + return tcpip.ErrBadLocalAddress + } + + return a.removePermanentEndpointLocked(addrState) +} + +// RemovePermanentEndpoint removes the passed endpoint if it is associated with +// a and permanent. +func (a *AddressableEndpointState) RemovePermanentEndpoint(ep AddressEndpoint) *tcpip.Error { + addrState, ok := ep.(*addressState) + if !ok || addrState.addressableEndpointState != a { + return tcpip.ErrInvalidEndpointState + } + + return a.removePermanentEndpointLocked(addrState) +} + +// removePermanentAddressLocked is like RemovePermanentAddress but with locking +// requirements. +// +// Precondition: a.mu must be write locked. +func (a *AddressableEndpointState) removePermanentEndpointLocked(addrState *addressState) *tcpip.Error { + if !addrState.GetKind().IsPermanent() { + return tcpip.ErrBadLocalAddress + } + + addrState.SetKind(PermanentExpired) + a.decAddressRefLocked(addrState) + return nil +} + +// decAddressRef decrements the address's reference count and releases it once +// the reference count hits 0. +func (a *AddressableEndpointState) decAddressRef(addrState *addressState) { + a.mu.Lock() + defer a.mu.Unlock() + a.decAddressRefLocked(addrState) +} + +// decAddressRefLocked is like decAddressRef but with locking requirements. +// +// Precondition: a.mu must be write locked. +func (a *AddressableEndpointState) decAddressRefLocked(addrState *addressState) { + addrState.mu.Lock() + defer addrState.mu.Unlock() + + if addrState.mu.refs == 0 { + panic(fmt.Sprintf("attempted to decrease ref count for AddressEndpoint w/ addr = %s when it is already released", addrState.addr)) + } + + addrState.mu.refs-- + + if addrState.mu.refs != 0 { + return + } + + // A non-expired permanent address must not have its reference count dropped + // to 0. + if addrState.mu.kind.IsPermanent() { + panic(fmt.Sprintf("permanent addresses should be removed through the AddressableEndpoint: addr = %s, kind = %d", addrState.addr, addrState.mu.kind)) + } + + a.releaseAddressStateLocked(addrState) +} + +// AcquireAssignedAddress implements AddressableEndpoint. +func (a *AddressableEndpointState) AcquireAssignedAddress(localAddr tcpip.Address, allowTemp bool, tempPEB PrimaryEndpointBehavior) AddressEndpoint { + a.mu.Lock() + defer a.mu.Unlock() + + if addrState, ok := a.mu.endpoints[localAddr]; ok { + if !addrState.IsAssigned(allowTemp) { + return nil + } + + if !addrState.IncRef() { + panic(fmt.Sprintf("failed to increase the reference count for address = %s", addrState.addr)) + } + + return addrState + } + + if !allowTemp { + return nil + } + + addr := localAddr.WithPrefix() + ep, err := a.addAndAcquireAddressLocked(addr, tempPEB, AddressConfigStatic, false /* deprecated */, false /* permanent */) + if err != nil { + // addAndAcquireAddressLocked only returns an error if the address is + // already assigned but we just checked above if the address exists so we + // expect no error. + panic(fmt.Sprintf("a.addAndAcquireAddressLocked(%s, %d, %d, false, false): %s", addr, tempPEB, AddressConfigStatic, err)) + } + // From https://golang.org/doc/faq#nil_error: + // + // Under the covers, interfaces are implemented as two elements, a type T and + // a value V. + // + // An interface value is nil only if the V and T are both unset, (T=nil, V is + // not set), In particular, a nil interface will always hold a nil type. If we + // store a nil pointer of type *int inside an interface value, the inner type + // will be *int regardless of the value of the pointer: (T=*int, V=nil). Such + // an interface value will therefore be non-nil even when the pointer value V + // inside is nil. + // + // Since addAndAcquireAddressLocked returns a nil value with a non-nil type, + // we need to explicitly return nil below if ep is (a typed) nil. + if ep == nil { + return nil + } + return ep +} + +// AcquirePrimaryAddress implements AddressableEndpoint. +func (a *AddressableEndpointState) AcquirePrimaryAddress(remoteAddr tcpip.Address, allowExpired bool) AddressEndpoint { + a.mu.RLock() + defer a.mu.RUnlock() + + var deprecatedEndpoint *addressState + for _, ep := range a.mu.primary { + if !ep.IsAssigned(allowExpired) { + continue + } + + if !ep.Deprecated() { + if ep.IncRef() { + // ep is not deprecated, so return it immediately. + // + // If we kept track of a deprecated endpoint, decrement its reference + // count since it was incremented when we decided to keep track of it. + if deprecatedEndpoint != nil { + a.decAddressRefLocked(deprecatedEndpoint) + deprecatedEndpoint = nil + } + + return ep + } + } else if deprecatedEndpoint == nil && ep.IncRef() { + // We prefer an endpoint that is not deprecated, but we keep track of + // ep in case a doesn't have any non-deprecated endpoints. + // + // If we end up finding a more preferred endpoint, ep's reference count + // will be decremented. + deprecatedEndpoint = ep + } + } + + // a doesn't have any valid non-deprecated endpoints, so return + // deprecatedEndpoint (which may be nil if a doesn't have any valid deprecated + // endpoints either). + if deprecatedEndpoint == nil { + return nil + } + return deprecatedEndpoint +} + +// PrimaryAddresses implements AddressableEndpoint. +func (a *AddressableEndpointState) PrimaryAddresses() []tcpip.AddressWithPrefix { + a.mu.RLock() + defer a.mu.RUnlock() + + var addrs []tcpip.AddressWithPrefix + for _, ep := range a.mu.primary { + // Don't include tentative, expired or temporary endpoints + // to avoid confusion and prevent the caller from using + // those. + switch ep.GetKind() { + case PermanentTentative, PermanentExpired, Temporary: + continue + } + + addrs = append(addrs, ep.AddressWithPrefix()) + } + + return addrs +} + +// PermanentAddresses implements AddressableEndpoint. +func (a *AddressableEndpointState) PermanentAddresses() []tcpip.AddressWithPrefix { + a.mu.RLock() + defer a.mu.RUnlock() + + var addrs []tcpip.AddressWithPrefix + for _, ep := range a.mu.endpoints { + if !ep.GetKind().IsPermanent() { + continue + } + + addrs = append(addrs, ep.AddressWithPrefix()) + } + + return addrs +} + +// JoinGroup implements GroupAddressableEndpoint. +func (a *AddressableEndpointState) JoinGroup(group tcpip.Address) (bool, *tcpip.Error) { + a.mu.Lock() + defer a.mu.Unlock() + + joins, ok := a.mu.groups[group] + if !ok { + ep, err := a.addAndAcquireAddressLocked(group.WithPrefix(), NeverPrimaryEndpoint, AddressConfigStatic, false /* deprecated */, true /* permanent */) + if err != nil { + return false, err + } + // We have no need for the address endpoint. + a.decAddressRefLocked(ep) + } + + a.mu.groups[group] = joins + 1 + return !ok, nil +} + +// LeaveGroup implements GroupAddressableEndpoint. +func (a *AddressableEndpointState) LeaveGroup(group tcpip.Address) (bool, *tcpip.Error) { + a.mu.Lock() + defer a.mu.Unlock() + + joins, ok := a.mu.groups[group] + if !ok { + return false, tcpip.ErrBadLocalAddress + } + + if joins == 1 { + a.removeGroupAddressLocked(group) + delete(a.mu.groups, group) + return true, nil + } + + a.mu.groups[group] = joins - 1 + return false, nil +} + +// IsInGroup implements GroupAddressableEndpoint. +func (a *AddressableEndpointState) IsInGroup(group tcpip.Address) bool { + a.mu.RLock() + defer a.mu.RUnlock() + _, ok := a.mu.groups[group] + return ok +} + +func (a *AddressableEndpointState) removeGroupAddressLocked(group tcpip.Address) { + if err := a.removePermanentAddressLocked(group); err != nil { + // removePermanentEndpointLocked would only return an error if group is + // not bound to the addressable endpoint, but we know it MUST be assigned + // since we have group in our map of groups. + panic(fmt.Sprintf("error removing group address = %s: %s", group, err)) + } +} + +// Cleanup forcefully leaves all groups and removes all permanent addresses. +func (a *AddressableEndpointState) Cleanup() { + a.mu.Lock() + defer a.mu.Unlock() + + for group := range a.mu.groups { + a.removeGroupAddressLocked(group) + } + a.mu.groups = make(map[tcpip.Address]uint32) + + for _, ep := range a.mu.endpoints { + // removePermanentEndpointLocked returns tcpip.ErrBadLocalAddress if ep is + // not a permanent address. + if err := a.removePermanentEndpointLocked(ep); err != nil && err != tcpip.ErrBadLocalAddress { + panic(fmt.Sprintf("unexpected error from removePermanentEndpointLocked(%s): %s", ep.addr, err)) + } + } +} + +var _ AddressEndpoint = (*addressState)(nil) + +// addressState holds state for an address. +type addressState struct { + addressableEndpointState *AddressableEndpointState + addr tcpip.AddressWithPrefix + + // Lock ordering (from outer to inner lock ordering): + // + // AddressableEndpointState.mu + // addressState.mu + mu struct { + sync.RWMutex + + refs uint32 + kind AddressKind + configType AddressConfigType + deprecated bool + } +} + +// NetworkEndpoint implements AddressEndpoint. +func (a *addressState) NetworkEndpoint() NetworkEndpoint { + return a.addressableEndpointState.networkEndpoint +} + +// AddressWithPrefix implements AddressEndpoint. +func (a *addressState) AddressWithPrefix() tcpip.AddressWithPrefix { + return a.addr +} + +// GetKind implements AddressEndpoint. +func (a *addressState) GetKind() AddressKind { + a.mu.RLock() + defer a.mu.RUnlock() + return a.mu.kind +} + +// SetKind implements AddressEndpoint. +func (a *addressState) SetKind(kind AddressKind) { + a.mu.Lock() + defer a.mu.Unlock() + a.mu.kind = kind +} + +// IsAssigned implements AddressEndpoint. +func (a *addressState) IsAssigned(allowExpired bool) bool { + if !a.addressableEndpointState.networkEndpoint.Enabled() { + return false + } + + switch a.GetKind() { + case PermanentTentative: + return false + case PermanentExpired: + return allowExpired + default: + return true + } +} + +// IncRef implements AddressEndpoint. +func (a *addressState) IncRef() bool { + a.mu.Lock() + defer a.mu.Unlock() + if a.mu.refs == 0 { + return false + } + + a.mu.refs++ + return true +} + +// DecRef implements AddressEndpoint. +func (a *addressState) DecRef() { + a.addressableEndpointState.decAddressRef(a) +} + +// ConfigType implements AddressEndpoint. +func (a *addressState) ConfigType() AddressConfigType { + a.mu.RLock() + defer a.mu.RUnlock() + return a.mu.configType +} + +// SetDeprecated implements AddressEndpoint. +func (a *addressState) SetDeprecated(d bool) { + a.mu.Lock() + defer a.mu.Unlock() + a.mu.deprecated = d +} + +// Deprecated implements AddressEndpoint. +func (a *addressState) Deprecated() bool { + a.mu.RLock() + defer a.mu.RUnlock() + return a.mu.deprecated +} |