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registry/{storage,handlers}: limit content sizes

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Under certain circumstances, the use of `StorageDriver.GetContent` can
result in unbounded memory allocations. In particualr, this happens when
accessing a layer through the manifests endpoint.

This problem is mitigated by setting a 4MB limit when using to access
content that may have been accepted from a user. In practice, this means
setting the limit with the use of `BlobProvider.Get` by wrapping
`StorageDriver.GetContent` in a helper that uses `StorageDriver.Reader`
with a `limitReader` that returns an error.

When mitigating this security issue, we also noticed that the size of
manifests uploaded to the registry is also unlimited. We apply similar
logic to the request body of payloads that are full buffered.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day
2017-07-06 16:01:26 -07:00
parent f86db6b226
commit 55ea440428
5 changed files with 91 additions and 13 deletions
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13
registry/handlers/helpers.go
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@@ -6,7 +6,6 @@ import (
"net/http"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/registry/api/errcode"
)
// closeResources closes all the provided resources after running the target
@@ -23,7 +22,9 @@ func closeResources(handler http.Handler, closers ...io.Closer) http.Handler {
// copyFullPayload copies the payload of an HTTP request to destWriter. If it
// receives less content than expected, and the client disconnected during the
// upload, it avoids sending a 400 error to keep the logs cleaner.
func copyFullPayload(responseWriter http.ResponseWriter, r *http.Request, destWriter io.Writer, context ctxu.Context, action string, errSlice *errcode.Errors) error {
//
// The copy will be limited to `limit` bytes, if limit is greater than zero.
func copyFullPayload(responseWriter http.ResponseWriter, r *http.Request, destWriter io.Writer, limit int64, context ctxu.Context, action string) error {
// Get a channel that tells us if the client disconnects
var clientClosed <-chan bool
if notifier, ok := responseWriter.(http.CloseNotifier); ok {
@@ -32,8 +33,13 @@ func copyFullPayload(responseWriter http.ResponseWriter, r *http.Request, destWr
ctxu.GetLogger(context).Warnf("the ResponseWriter does not implement CloseNotifier (type: %T)", responseWriter)
}
var body = r.Body
if limit > 0 {
body = http.MaxBytesReader(responseWriter, body, limit)
}
// Read in the data, if any.
copied, err := io.Copy(destWriter, r.Body)
copied, err := io.Copy(destWriter, body)
if clientClosed != nil && (err != nil || (r.ContentLength > 0 && copied < r.ContentLength)) {
// Didn't receive as much content as expected. Did the client
// disconnect during the request? If so, avoid returning a 400
@@ -58,7 +64,6 @@ func copyFullPayload(responseWriter http.ResponseWriter, r *http.Request, destWr
if err != nil {
ctxu.GetLogger(context).Errorf("unknown error reading request payload: %v", err)
*errSlice = append(*errSlice, errcode.ErrorCodeUnknown.WithDetail(err))
return err
}