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eth, les: add sanity checks for unbounded block fields (#19573)

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This PR adds some hardening in the lower levels of the protocol stack, to bail early on invalid data. Primarily, attacks that this PR protects against are on the "annoyance"-level, which would otherwise write a couple of megabytes of data into the log output, which is a bit resource intensive.
This commit is contained in:
Martin Holst Swende
2019-07-08 11:42:22 +02:00
committed by Felix Lange
parent 5bc9ccfa0a
commit cdfe9a3a2a
6 changed files with 57 additions and 5 deletions
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8
eth/fetcher/fetcher.go
View File

@ -685,7 +685,7 @@ func (f *Fetcher) forgetHash(hash common.Hash) {
// Remove all pending announces and decrement DOS counters
for _, announce := range f.announced[hash] {
f.announces[announce.origin]--
if f.announces[announce.origin] == 0 {
if f.announces[announce.origin] <= 0 {
delete(f.announces, announce.origin)
}
}
@ -696,7 +696,7 @@ func (f *Fetcher) forgetHash(hash common.Hash) {
// Remove any pending fetches and decrement the DOS counters
if announce := f.fetching[hash]; announce != nil {
f.announces[announce.origin]--
if f.announces[announce.origin] == 0 {
if f.announces[announce.origin] <= 0 {
delete(f.announces, announce.origin)
}
delete(f.fetching, hash)
@ -705,7 +705,7 @@ func (f *Fetcher) forgetHash(hash common.Hash) {
// Remove any pending completion requests and decrement the DOS counters
for _, announce := range f.fetched[hash] {
f.announces[announce.origin]--
if f.announces[announce.origin] == 0 {
if f.announces[announce.origin] <= 0 {
delete(f.announces, announce.origin)
}
}
@ -714,7 +714,7 @@ func (f *Fetcher) forgetHash(hash common.Hash) {
// Remove any pending completions and decrement the DOS counters
if announce := f.completing[hash]; announce != nil {
f.announces[announce.origin]--
if f.announces[announce.origin] == 0 {
if f.announces[announce.origin] <= 0 {
delete(f.announces, announce.origin)
}
delete(f.completing, hash)

3
eth/handler.go
View File

@ -697,6 +697,9 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
if err := msg.Decode(&request); err != nil {
return errResp(ErrDecode, "%v: %v", msg, err)
}
if err := request.sanityCheck(); err != nil {
return err
}
request.Block.ReceivedAt = msg.ReceivedAt
request.Block.ReceivedFrom = p

13
eth/protocol.go
View File

@ -173,6 +173,19 @@ type newBlockData struct {
TD *big.Int
}
// sanityCheck verifies that the values are reasonable, as a DoS protection
func (request *newBlockData) sanityCheck() error {
if err := request.Block.SanityCheck(); err != nil {
return err
}
//TD at mainnet block #7753254 is 76 bits. If it becomes 100 million times
// larger, it will still fit within 100 bits
if tdlen := request.TD.BitLen(); tdlen > 100 {
return fmt.Errorf("too large block TD: bitlen %d", tdlen)
}
return nil
}
// blockBody represents the data content of a single block.
type blockBody struct {
Transactions []*types.Transaction // Transactions contained within a block