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net/portmapper: check returned epoch from PMP and PCP protocols

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If the epoch that we see during a Probe is less than the existing epoch,
it means that the gateway has either restarted or reset its
configuration, and an existing mapping is no longer valid. Reset any
saved mapping(s) if we detect this case so that a future
createOrGetMapping will not attempt to re-use it.

Updates #10597

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ie3cddaf625cb94a29885f7a1eeea25dbf6b97b47
This commit is contained in:
Andrew Dunham 2023-12-20 19:24:03 -05:00
parent b084888e4d
commit fa3639783c
2 changed files with 65 additions and 3 deletions
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4
net/portmapper/pcp.go
View File

@ -54,8 +54,7 @@ type pcpMapping struct {
renewAfter time.Time
goodUntil time.Time
// TODO should this also contain an epoch?
// Doesn't seem to be used elsewhere, but can use it for validation at some point.
epoch uint32
}
func (p *pcpMapping) MappingType() string { return "pcp" }
@ -140,6 +139,7 @@ func parsePCPMapResponse(resp []byte) (*pcpMapping, error) {
external: external,
renewAfter: now.Add(lifetime / 2),
goodUntil: now.Add(lifetime),
epoch: res.Epoch,
}
return mapping, nil

64
net/portmapper/portmapper.go
View File

@ -90,11 +90,14 @@ type Client struct {
lastProbe time.Time
// The following PMP fields are populated during Probe
pmpPubIP netip.Addr // non-zero if known
pmpPubIPTime time.Time // time pmpPubIP last verified
pmpLastEpoch uint32
pcpSawTime time.Time // time we last saw PCP was available
// The following PCP fields are populated during Probe
pcpSawTime time.Time // time we last saw PCP was available
pcpLastEpoch uint32
uPnPSawTime time.Time // time we last saw UPnP was available
uPnPMetas []uPnPDiscoResponse // UPnP UDP discovery responses
@ -324,9 +327,14 @@ func (c *Client) invalidateMappingsLocked(releaseOld bool) {
}
c.mapping = nil
}
c.pmpPubIP = netip.Addr{}
c.pmpPubIPTime = time.Time{}
c.pmpLastEpoch = 0
c.pcpSawTime = time.Time{}
c.pcpLastEpoch = 0
c.uPnPSawTime = time.Time{}
c.uPnPMetas = nil
}
@ -988,7 +996,9 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
if pres.OpCode == pcpOpReply|pcpOpAnnounce {
pcpHeard = true
c.mu.Lock()
c.maybeInvalidatePCPMappingLocked(pres.Epoch) // must be before we write to c.pcp*
c.pcpSawTime = time.Now()
c.pcpLastEpoch = pres.Epoch
c.mu.Unlock()
switch pres.ResultCode {
case pcpCodeOK:
@ -1026,6 +1036,7 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
c.logf("[v1] Got PMP response; IP: %v, epoch: %v", pres.PublicAddr, pres.SecondsSinceEpoch)
res.PMP = true
c.mu.Lock()
c.maybeInvalidatePMPMappingLocked(pres.SecondsSinceEpoch) // must be before we write to c.pmp*
c.pmpPubIP = pres.PublicAddr
c.pmpPubIPTime = time.Now()
c.pmpLastEpoch = pres.SecondsSinceEpoch
@ -1051,6 +1062,57 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
}
}
func (c *Client) maybeInvalidatePMPMappingLocked(epoch uint32) {
if epoch == 0 || c.mapping == nil {
return
}
m, ok := c.mapping.(*pmpMapping)
if !ok {
return
}
if epoch >= m.epoch {
// Epoch increased, which is fine.
//
// TODO: we should more closely follow RFC6887 § 8.5 which also
// requires us to check the current time and the time that this
// epoch was received at.
return
}
// Epoch decreased, so invalidate the mapping and clear PMP fields.
c.logf("invalidating PMP mappings since returned epoch %d < stored epoch %d", epoch, m.epoch)
c.mapping = nil
c.pmpPubIP = netip.Addr{}
c.pmpPubIPTime = time.Time{}
c.pmpLastEpoch = 0
}
func (c *Client) maybeInvalidatePCPMappingLocked(epoch uint32) {
if epoch == 0 || c.mapping == nil {
return
}
m, ok := c.mapping.(*pcpMapping)
if !ok {
return
}
if epoch >= m.epoch {
// Epoch increased, which is fine.
//
// TODO: we should more closely follow RFC6887 § 8.5 which also
// requires us to check the current time and the time that this
// epoch was received at.
return
}
// Epoch decreased, so invalidate the mapping and clear PCP fields.
c.logf("invalidating PCP mappings since returned epoch %d < stored epoch %d", epoch, m.epoch)
c.mapping = nil
c.pcpSawTime = time.Time{}
c.pcpLastEpoch = 0
}
var pmpReqExternalAddrPacket = []byte{pmpVersion, pmpOpMapPublicAddr} // 0, 0
const (