fix(sei-cosmos): harden paginated RPC queries against DoS via limit, offset, and count_total caps (PLT-361)

sei-cosmos/types/query/filtered_pagination.go

@@ -5,6 +5,8 @@ import (
 
 	"github.com/sei-protocol/sei-chain/sei-cosmos/codec"
 	"github.com/sei-protocol/sei-chain/sei-cosmos/store/types"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 // FilteredPaginate does pagination of all the results in the PrefixStore based on the
@@ -36,27 +38,38 @@ func FilteredPaginate(
 		return nil, fmt.Errorf("invalid request, either offset or key is expected, got both")
 	}
 
+	if err := VerifyPaginationOffset(offset); err != nil {
+		return nil, err
+	}
+
 	if limit == 0 {
 		limit = DefaultLimit
+	}
 
-		// count total results when the limit is zero/not supplied
-		countTotal = true
+	if err := VerifyPaginationLimit(limit); err != nil {
+		return nil, err
 	}
 
 	if len(key) != 0 {
 		iterator := getIterator(prefixStore, key, reverse)
 		defer func() { _ = iterator.Close() }()
 
 		var (
-			numHits uint64
-			nextKey []byte
+			numHits   uint64
+			nextKey   []byte
+			totalIter uint64
 		)
 
 		for ; iterator.Valid(); iterator.Next() {
+			totalIter++
 			if numHits == limit {
 				nextKey = iterator.Key()
 				break
 			}
+			if totalIter > MaxScanLimit {
+				return nil, status.Errorf(codes.InvalidArgument,
+					"scanned more than %d entries without filling the page; use a more specific key prefix or reduce limit", MaxScanLimit)
+			}
 
 			if iterator.Error() != nil {
 				return nil, iterator.Error()
@@ -83,11 +96,30 @@ func FilteredPaginate(
 	end := offset + limit
 
 	var (
-		numHits uint64
-		nextKey []byte
+		numHits          uint64
+		nextKey          []byte
+		totalIter        uint64
+		pageCompleteIter uint64
 	)
 
 	for ; iterator.Valid(); iterator.Next() {
+		totalIter++
+		// Phase 1: page not yet complete — cap raw iterations to prevent full-store
+		// walks when the filter produces too few hits to fill the page.
+		if numHits < end && totalIter > offset+MaxScanLimit {
+			return nil, status.Errorf(codes.InvalidArgument,
+				"scanned more than %d entries without filling the page; use key-based pagination instead", MaxScanLimit)
+		}
+		// Phase 2: page complete — cap how far past the page we scan for nextKey/count_total.
+		if pageCompleteIter > MaxScanLimit {
+			if !countTotal {
+				// Page is already assembled; no next hit found within scan window → no next page.
+				break
+			}
+			return nil, status.Errorf(codes.InvalidArgument,
+				"scanned more than %d entries past the end of the page; use key-based pagination instead", MaxScanLimit)
+		}
+
 		if iterator.Error() != nil {
 			return nil, iterator.Error()
 		}
@@ -102,6 +134,10 @@ func FilteredPaginate(
 			numHits++
 		}
 
+		if numHits >= end {
+			pageCompleteIter++
+		}
+
 		if numHits == end+1 {
 			nextKey = iterator.Key()
 
@@ -150,27 +186,38 @@ func GenericFilteredPaginate[T codec.ProtoMarshaler, F codec.ProtoMarshaler](
 		return results, nil, fmt.Errorf("invalid request, either offset or key is expected, got both")
 	}
 
+	if err := VerifyPaginationOffset(offset); err != nil {
+		return results, nil, err
+	}
+
 	if limit == 0 {
 		limit = DefaultLimit
+	}
 
-		// count total results when the limit is zero/not supplied
-		countTotal = true
+	if err := VerifyPaginationLimit(limit); err != nil {
+		return results, nil, err
 	}
 
 	if len(key) != 0 {
 		iterator := getIterator(prefixStore, key, reverse)
 		defer func() { _ = iterator.Close() }()
 
 		var (
-			numHits uint64
-			nextKey []byte
+			numHits   uint64
+			nextKey   []byte
+			totalIter uint64
 		)
 
 		for ; iterator.Valid(); iterator.Next() {
+			totalIter++
 			if numHits == limit {
 				nextKey = iterator.Key()
 				break
 			}
+			if totalIter > MaxScanLimit {
+				return nil, nil, status.Errorf(codes.InvalidArgument,
+					"scanned more than %d entries without filling the page; use a more specific key prefix or reduce limit", MaxScanLimit)
+			}
 
 			if iterator.Error() != nil {
 				return nil, nil, iterator.Error()
@@ -205,11 +252,30 @@ func GenericFilteredPaginate[T codec.ProtoMarshaler, F codec.ProtoMarshaler](
 	end := offset + limit
 
 	var (
-		numHits uint64
-		nextKey []byte
+		numHits          uint64
+		nextKey          []byte
+		totalIter        uint64
+		pageCompleteIter uint64
 	)
 
 	for ; iterator.Valid(); iterator.Next() {
+		totalIter++
+		// Phase 1: page not yet complete — cap raw iterations to prevent full-store
+		// walks when the filter produces too few hits to fill the page.
+		if numHits < end && totalIter > offset+MaxScanLimit {
+			return nil, nil, status.Errorf(codes.InvalidArgument,
+				"scanned more than %d entries without filling the page; use key-based pagination instead", MaxScanLimit)
+		}
+		// Phase 2: page complete — cap how far past the page we scan for nextKey/count_total.
+		if pageCompleteIter > MaxScanLimit {
+			if !countTotal {
+				// Page is already assembled; no next hit found within scan window → no next page.
+				break
+			}
+			return nil, nil, status.Errorf(codes.InvalidArgument,
+				"scanned more than %d entries past the end of the page; use key-based pagination instead", MaxScanLimit)
+		}
+
 		if iterator.Error() != nil {
 			return nil, nil, iterator.Error()
 		}
@@ -234,6 +300,10 @@ func GenericFilteredPaginate[T codec.ProtoMarshaler, F codec.ProtoMarshaler](
 			numHits++
 		}
 
+		if numHits >= end {
+			pageCompleteIter++
+		}
+
 		if numHits == end+1 {
 			if nextKey == nil {
 				nextKey = iterator.Key()

sei-cosmos/types/query/filtered_pagination_test.go

@@ -47,7 +47,7 @@ func (s *paginationTestSuite) TestFilteredPaginations() {
 	s.Require().NoError(err)
 	s.Require().NotNil(res)
 	s.Require().Equal(4, len(balances))
-	s.Require().Equal(uint64(4), res.Total)
+	s.Require().Equal(uint64(0), res.Total)
 	s.Require().Nil(res.NextKey)
 
 	s.T().Log("verify nextKey is returned if there are more results")
@@ -79,7 +79,7 @@ func (s *paginationTestSuite) TestFilteredPaginations() {
 	s.Require().NoError(err)
 	s.Require().NotNil(res)
 	s.Require().Equal(4, len(balances))
-	s.Require().Equal(uint64(4), res.Total)
+	s.Require().Equal(uint64(0), res.Total)
 
 	s.T().Log("verify with offset")
 	pageReq = &query.PageRequest{Offset: 2, Limit: 2}
@@ -122,7 +122,7 @@ func (s *paginationTestSuite) TestReverseFilteredPaginations() {
 	s.Require().NoError(err)
 	s.Require().NotNil(res)
 	s.Require().Equal(10, len(balns))
-	s.Require().Equal(uint64(10), res.Total)
+	s.Require().Equal(uint64(0), res.Total)
 	s.Require().Nil(res.NextKey)
 
 	s.T().Log("verify default limit")
@@ -131,7 +131,7 @@ func (s *paginationTestSuite) TestReverseFilteredPaginations() {
 	s.Require().NoError(err)
 	s.Require().NotNil(res)
 	s.Require().Equal(10, len(balns))
-	s.Require().Equal(uint64(10), res.Total)
+	s.Require().Equal(uint64(0), res.Total)
 
 	s.T().Log("verify nextKey is returned if there are more results")
 	pageReq = &query.PageRequest{Limit: 2, CountTotal: true, Reverse: true}
@@ -170,6 +170,68 @@ func (s *paginationTestSuite) TestReverseFilteredPaginations() {
 
 }
 
+func (s *paginationTestSuite) TestFilteredPaginateMaxLimitExceeded() {
+	app, ctx, _ := setupTest(s.T())
+	store := ctx.KVStore(app.GetKey(types.StoreKey))
+
+	_, err := query.FilteredPaginate(store, &query.PageRequest{Limit: query.MaxLimit + 1}, func(_ []byte, _ []byte, _ bool) (bool, error) {
+		return false, nil
+	})
+	s.Require().Error(err)
+	s.Require().Contains(err.Error(), "exceeds maximum allowed limit")
+}
+
+func (s *paginationTestSuite) TestFilteredPaginateOffsetExceedsMax() {
+	app, ctx, _ := setupTest(s.T())
+	kvStore := ctx.KVStore(app.GetKey(types.StoreKey))
+
+	_, err := query.FilteredPaginate(kvStore, &query.PageRequest{Offset: query.MaxOffset + 1}, func(_ []byte, _ []byte, _ bool) (bool, error) {
+		return false, nil
+	})
+	s.Require().Error(err)
+	s.Require().Contains(err.Error(), "exceeds maximum allowed offset")
+
+	_, err = query.FilteredPaginate(kvStore, &query.PageRequest{Offset: query.MaxOffset}, func(_ []byte, _ []byte, _ bool) (bool, error) {
+		return false, nil
+	})
+	s.Require().NoError(err)
+}
+
+func (s *paginationTestSuite) TestFilteredPaginateCountTotalScanLimitExceeded() {
+	app, ctx, _ := setupTest(s.T())
+	kvStore := prefix.NewStore(ctx.KVStore(app.GetKey(types.StoreKey)), []byte("filteredscanlimit/"))
+
+	numItems := int(query.MaxScanLimit) + 2
+	for i := 0; i < numItems; i++ {
+		kvStore.Set([]byte(fmt.Sprintf("%08d", i)), []byte("v"))
+	}
+
+	_, err := query.FilteredPaginate(kvStore, &query.PageRequest{Limit: 1, CountTotal: true}, func(_ []byte, _ []byte, _ bool) (bool, error) {
+		return true, nil
+	})
+	s.Require().Error(err)
+	s.Require().Contains(err.Error(), "scanned more than")
+}
+
+func (s *paginationTestSuite) TestFilteredPaginateCountTotalScanLimitExceededNoHits() {
+	app, ctx, _ := setupTest(s.T())
+	kvStore := prefix.NewStore(ctx.KVStore(app.GetKey(types.StoreKey)), []byte("filteredscanlimitnohits/"))
+
+	// Phase 1 fires when totalIter > offset + MaxScanLimit = 10001
+	pageReq := &query.PageRequest{Offset: 1, CountTotal: true}
+	numItems := int(query.MaxScanLimit) + 2
+	for i := 0; i < numItems; i++ {
+		kvStore.Set([]byte(fmt.Sprintf("%08d", i)), []byte("v"))
+	}
+
+	// filter returns no hits — numHits never reaches end, Phase 1 guard must fire
+	_, err := query.FilteredPaginate(kvStore, pageReq, func(_ []byte, _ []byte, _ bool) (bool, error) {
+		return false, nil
+	})
+	s.Require().Error(err)
+	s.Require().Contains(err.Error(), "scanned more than")
+}
+
 func execFilterPaginate(store sdk.KVStore, pageReq *query.PageRequest, appCodec codec.Codec) (balances sdk.Coins, res *query.PageResponse, err error) {
 	balancesStore := prefix.NewStore(store, types.BalancesPrefix)
 	accountStore := prefix.NewStore(balancesStore, address.MustLengthPrefix(addr1))