distribution/registry/handlers/manifests.go
Stephen J Day 55ea440428
registry/{storage,handlers}: limit content sizes
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>
2017-07-06 17:13:39 -07:00

480 lines
14 KiB
Go

package handlers
import (
"bytes"
"fmt"
"net/http"
"strings"
"github.com/docker/distribution"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/manifest/manifestlist"
"github.com/docker/distribution/manifest/schema1"
"github.com/docker/distribution/manifest/schema2"
"github.com/docker/distribution/reference"
"github.com/docker/distribution/registry/api/errcode"
"github.com/docker/distribution/registry/api/v2"
"github.com/docker/distribution/registry/auth"
"github.com/gorilla/handlers"
"github.com/opencontainers/go-digest"
)
// These constants determine which architecture and OS to choose from a
// manifest list when downconverting it to a schema1 manifest.
const (
defaultArch = "amd64"
defaultOS = "linux"
maxManifestBodySize = 4 << 20
)
// manifestDispatcher takes the request context and builds the
// appropriate handler for handling manifest requests.
func manifestDispatcher(ctx *Context, r *http.Request) http.Handler {
manifestHandler := &manifestHandler{
Context: ctx,
}
reference := getReference(ctx)
dgst, err := digest.Parse(reference)
if err != nil {
// We just have a tag
manifestHandler.Tag = reference
} else {
manifestHandler.Digest = dgst
}
mhandler := handlers.MethodHandler{
"GET": http.HandlerFunc(manifestHandler.GetManifest),
"HEAD": http.HandlerFunc(manifestHandler.GetManifest),
}
if !ctx.readOnly {
mhandler["PUT"] = http.HandlerFunc(manifestHandler.PutManifest)
mhandler["DELETE"] = http.HandlerFunc(manifestHandler.DeleteManifest)
}
return mhandler
}
// manifestHandler handles http operations on image manifests.
type manifestHandler struct {
*Context
// One of tag or digest gets set, depending on what is present in context.
Tag string
Digest digest.Digest
}
// GetManifest fetches the image manifest from the storage backend, if it exists.
func (imh *manifestHandler) GetManifest(w http.ResponseWriter, r *http.Request) {
ctxu.GetLogger(imh).Debug("GetImageManifest")
manifests, err := imh.Repository.Manifests(imh)
if err != nil {
imh.Errors = append(imh.Errors, err)
return
}
var manifest distribution.Manifest
if imh.Tag != "" {
tags := imh.Repository.Tags(imh)
desc, err := tags.Get(imh, imh.Tag)
if err != nil {
if _, ok := err.(distribution.ErrTagUnknown); ok {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnknown.WithDetail(err))
} else {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
}
return
}
imh.Digest = desc.Digest
}
if etagMatch(r, imh.Digest.String()) {
w.WriteHeader(http.StatusNotModified)
return
}
var options []distribution.ManifestServiceOption
if imh.Tag != "" {
options = append(options, distribution.WithTag(imh.Tag))
}
manifest, err = manifests.Get(imh, imh.Digest, options...)
if err != nil {
if _, ok := err.(distribution.ErrManifestUnknownRevision); ok {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnknown.WithDetail(err))
} else {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
}
return
}
supportsSchema2 := false
supportsManifestList := false
// this parsing of Accept headers is not quite as full-featured as godoc.org's parser, but we don't care about "q=" values
// https://github.com/golang/gddo/blob/e91d4165076d7474d20abda83f92d15c7ebc3e81/httputil/header/header.go#L165-L202
for _, acceptHeader := range r.Header["Accept"] {
// r.Header[...] is a slice in case the request contains the same header more than once
// if the header isn't set, we'll get the zero value, which "range" will handle gracefully
// we need to split each header value on "," to get the full list of "Accept" values (per RFC 2616)
// https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1
for _, mediaType := range strings.Split(acceptHeader, ",") {
// remove "; q=..." if present
if i := strings.Index(mediaType, ";"); i >= 0 {
mediaType = mediaType[:i]
}
// it's common (but not required) for Accept values to be space separated ("a/b, c/d, e/f")
mediaType = strings.TrimSpace(mediaType)
if mediaType == schema2.MediaTypeManifest {
supportsSchema2 = true
}
if mediaType == manifestlist.MediaTypeManifestList {
supportsManifestList = true
}
}
}
schema2Manifest, isSchema2 := manifest.(*schema2.DeserializedManifest)
manifestList, isManifestList := manifest.(*manifestlist.DeserializedManifestList)
// Only rewrite schema2 manifests when they are being fetched by tag.
// If they are being fetched by digest, we can't return something not
// matching the digest.
if imh.Tag != "" && isSchema2 && !supportsSchema2 {
// Rewrite manifest in schema1 format
ctxu.GetLogger(imh).Infof("rewriting manifest %s in schema1 format to support old client", imh.Digest.String())
manifest, err = imh.convertSchema2Manifest(schema2Manifest)
if err != nil {
return
}
} else if imh.Tag != "" && isManifestList && !supportsManifestList {
// Rewrite manifest in schema1 format
ctxu.GetLogger(imh).Infof("rewriting manifest list %s in schema1 format to support old client", imh.Digest.String())
// Find the image manifest corresponding to the default
// platform
var manifestDigest digest.Digest
for _, manifestDescriptor := range manifestList.Manifests {
if manifestDescriptor.Platform.Architecture == defaultArch && manifestDescriptor.Platform.OS == defaultOS {
manifestDigest = manifestDescriptor.Digest
break
}
}
if manifestDigest == "" {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnknown)
return
}
manifest, err = manifests.Get(imh, manifestDigest)
if err != nil {
if _, ok := err.(distribution.ErrManifestUnknownRevision); ok {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnknown.WithDetail(err))
} else {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
}
return
}
// If necessary, convert the image manifest
if schema2Manifest, isSchema2 := manifest.(*schema2.DeserializedManifest); isSchema2 && !supportsSchema2 {
manifest, err = imh.convertSchema2Manifest(schema2Manifest)
if err != nil {
return
}
} else {
imh.Digest = manifestDigest
}
}
ct, p, err := manifest.Payload()
if err != nil {
return
}
w.Header().Set("Content-Type", ct)
w.Header().Set("Content-Length", fmt.Sprint(len(p)))
w.Header().Set("Docker-Content-Digest", imh.Digest.String())
w.Header().Set("Etag", fmt.Sprintf(`"%s"`, imh.Digest))
w.Write(p)
}
func (imh *manifestHandler) convertSchema2Manifest(schema2Manifest *schema2.DeserializedManifest) (distribution.Manifest, error) {
targetDescriptor := schema2Manifest.Target()
blobs := imh.Repository.Blobs(imh)
configJSON, err := blobs.Get(imh, targetDescriptor.Digest)
if err != nil {
if err == distribution.ErrBlobUnknown {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestInvalid.WithDetail(err))
} else {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
}
return nil, err
}
ref := imh.Repository.Named()
if imh.Tag != "" {
ref, err = reference.WithTag(ref, imh.Tag)
if err != nil {
imh.Errors = append(imh.Errors, v2.ErrorCodeTagInvalid.WithDetail(err))
return nil, err
}
}
builder := schema1.NewConfigManifestBuilder(imh.Repository.Blobs(imh), imh.Context.App.trustKey, ref, configJSON)
for _, d := range schema2Manifest.Layers {
if err := builder.AppendReference(d); err != nil {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestInvalid.WithDetail(err))
return nil, err
}
}
manifest, err := builder.Build(imh)
if err != nil {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestInvalid.WithDetail(err))
return nil, err
}
imh.Digest = digest.FromBytes(manifest.(*schema1.SignedManifest).Canonical)
return manifest, nil
}
func etagMatch(r *http.Request, etag string) bool {
for _, headerVal := range r.Header["If-None-Match"] {
if headerVal == etag || headerVal == fmt.Sprintf(`"%s"`, etag) { // allow quoted or unquoted
return true
}
}
return false
}
// PutManifest validates and stores a manifest in the registry.
func (imh *manifestHandler) PutManifest(w http.ResponseWriter, r *http.Request) {
ctxu.GetLogger(imh).Debug("PutImageManifest")
manifests, err := imh.Repository.Manifests(imh)
if err != nil {
imh.Errors = append(imh.Errors, err)
return
}
var jsonBuf bytes.Buffer
if err := copyFullPayload(w, r, &jsonBuf, maxManifestBodySize, imh, "image manifest PUT"); err != nil {
// copyFullPayload reports the error if necessary
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestInvalid.WithDetail(err.Error()))
return
}
mediaType := r.Header.Get("Content-Type")
manifest, desc, err := distribution.UnmarshalManifest(mediaType, jsonBuf.Bytes())
if err != nil {
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestInvalid.WithDetail(err))
return
}
if imh.Digest != "" {
if desc.Digest != imh.Digest {
ctxu.GetLogger(imh).Errorf("payload digest does match: %q != %q", desc.Digest, imh.Digest)
imh.Errors = append(imh.Errors, v2.ErrorCodeDigestInvalid)
return
}
} else if imh.Tag != "" {
imh.Digest = desc.Digest
} else {
imh.Errors = append(imh.Errors, v2.ErrorCodeTagInvalid.WithDetail("no tag or digest specified"))
return
}
var options []distribution.ManifestServiceOption
if imh.Tag != "" {
options = append(options, distribution.WithTag(imh.Tag))
}
if err := imh.applyResourcePolicy(manifest); err != nil {
imh.Errors = append(imh.Errors, err)
return
}
_, err = manifests.Put(imh, manifest, options...)
if err != nil {
// TODO(stevvooe): These error handling switches really need to be
// handled by an app global mapper.
if err == distribution.ErrUnsupported {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnsupported)
return
}
if err == distribution.ErrAccessDenied {
imh.Errors = append(imh.Errors, errcode.ErrorCodeDenied)
return
}
switch err := err.(type) {
case distribution.ErrManifestVerification:
for _, verificationError := range err {
switch verificationError := verificationError.(type) {
case distribution.ErrManifestBlobUnknown:
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestBlobUnknown.WithDetail(verificationError.Digest))
case distribution.ErrManifestNameInvalid:
imh.Errors = append(imh.Errors, v2.ErrorCodeNameInvalid.WithDetail(err))
case distribution.ErrManifestUnverified:
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnverified)
default:
if verificationError == digest.ErrDigestInvalidFormat {
imh.Errors = append(imh.Errors, v2.ErrorCodeDigestInvalid)
} else {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown, verificationError)
}
}
}
case errcode.Error:
imh.Errors = append(imh.Errors, err)
default:
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
}
return
}
// Tag this manifest
if imh.Tag != "" {
tags := imh.Repository.Tags(imh)
err = tags.Tag(imh, imh.Tag, desc)
if err != nil {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
return
}
}
// Construct a canonical url for the uploaded manifest.
ref, err := reference.WithDigest(imh.Repository.Named(), imh.Digest)
if err != nil {
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
return
}
location, err := imh.urlBuilder.BuildManifestURL(ref)
if err != nil {
// NOTE(stevvooe): Given the behavior above, this absurdly unlikely to
// happen. We'll log the error here but proceed as if it worked. Worst
// case, we set an empty location header.
ctxu.GetLogger(imh).Errorf("error building manifest url from digest: %v", err)
}
w.Header().Set("Location", location)
w.Header().Set("Docker-Content-Digest", imh.Digest.String())
w.WriteHeader(http.StatusCreated)
}
// applyResourcePolicy checks whether the resource class matches what has
// been authorized and allowed by the policy configuration.
func (imh *manifestHandler) applyResourcePolicy(manifest distribution.Manifest) error {
allowedClasses := imh.App.Config.Policy.Repository.Classes
if len(allowedClasses) == 0 {
return nil
}
var class string
switch m := manifest.(type) {
case *schema1.SignedManifest:
class = "image"
case *schema2.DeserializedManifest:
switch m.Config.MediaType {
case schema2.MediaTypeImageConfig:
class = "image"
case schema2.MediaTypePluginConfig:
class = "plugin"
default:
message := fmt.Sprintf("unknown manifest class for %s", m.Config.MediaType)
return errcode.ErrorCodeDenied.WithMessage(message)
}
}
if class == "" {
return nil
}
// Check to see if class is allowed in registry
var allowedClass bool
for _, c := range allowedClasses {
if class == c {
allowedClass = true
break
}
}
if !allowedClass {
message := fmt.Sprintf("registry does not allow %s manifest", class)
return errcode.ErrorCodeDenied.WithMessage(message)
}
resources := auth.AuthorizedResources(imh)
n := imh.Repository.Named().Name()
var foundResource bool
for _, r := range resources {
if r.Name == n {
if r.Class == "" {
r.Class = "image"
}
if r.Class == class {
return nil
}
foundResource = true
}
}
// resource was found but no matching class was found
if foundResource {
message := fmt.Sprintf("repository not authorized for %s manifest", class)
return errcode.ErrorCodeDenied.WithMessage(message)
}
return nil
}
// DeleteManifest removes the manifest with the given digest from the registry.
func (imh *manifestHandler) DeleteManifest(w http.ResponseWriter, r *http.Request) {
ctxu.GetLogger(imh).Debug("DeleteImageManifest")
manifests, err := imh.Repository.Manifests(imh)
if err != nil {
imh.Errors = append(imh.Errors, err)
return
}
err = manifests.Delete(imh, imh.Digest)
if err != nil {
switch err {
case digest.ErrDigestUnsupported:
case digest.ErrDigestInvalidFormat:
imh.Errors = append(imh.Errors, v2.ErrorCodeDigestInvalid)
return
case distribution.ErrBlobUnknown:
imh.Errors = append(imh.Errors, v2.ErrorCodeManifestUnknown)
return
case distribution.ErrUnsupported:
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnsupported)
return
default:
imh.Errors = append(imh.Errors, errcode.ErrorCodeUnknown)
return
}
}
tagService := imh.Repository.Tags(imh)
referencedTags, err := tagService.Lookup(imh, distribution.Descriptor{Digest: imh.Digest})
if err != nil {
imh.Errors = append(imh.Errors, err)
return
}
for _, tag := range referencedTags {
if err := tagService.Untag(imh, tag); err != nil {
imh.Errors = append(imh.Errors, err)
return
}
}
w.WriteHeader(http.StatusAccepted)
}