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moby--moby/pkg/authorization/authz.go

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package authorization
import (
"bufio"
"bytes"
"fmt"
"io"
"net/http"
"strings"
"github.com/Sirupsen/logrus"
"github.com/docker/docker/pkg/ioutils"
)
const maxBodySize = 1048576 // 1MB
// NewCtx creates new authZ context, it is used to store authorization information related to a specific docker
// REST http session
// A context provides two method:
// Authenticate Request:
// Call authZ plugins with current REST request and AuthN response
// Request contains full HTTP packet sent to the docker daemon
// https://docs.docker.com/reference/api/docker_remote_api/
//
// Authenticate Response:
// Call authZ plugins with full info about current REST request, REST response and AuthN response
// The response from this method may contains content that overrides the daemon response
// This allows authZ plugins to filter privileged content
//
// If multiple authZ plugins are specified, the block/allow decision is based on ANDing all plugin results
// For response manipulation, the response from each plugin is piped between plugins. Plugin execution order
// is determined according to daemon parameters
func NewCtx(authZPlugins []Plugin, user, userAuthNMethod, requestMethod, requestURI string) *Ctx {
return &Ctx{
plugins: authZPlugins,
user: user,
userAuthNMethod: userAuthNMethod,
requestMethod: requestMethod,
requestURI: requestURI,
}
}
// Ctx stores a a single request-response interaction context
type Ctx struct {
user string
userAuthNMethod string
requestMethod string
requestURI string
plugins []Plugin
// authReq stores the cached request object for the current transaction
authReq *Request
}
// AuthZRequest authorized the request to the docker daemon using authZ plugins
func (ctx *Ctx) AuthZRequest(w http.ResponseWriter, r *http.Request) error {
var body []byte
if sendBody(ctx.requestURI, r.Header) && r.ContentLength > 0 && r.ContentLength < maxBodySize {
var err error
body, r.Body, err = drainBody(r.Body)
if err != nil {
return err
}
}
var h bytes.Buffer
if err := r.Header.Write(&h); err != nil {
return err
}
ctx.authReq = &Request{
User: ctx.user,
UserAuthNMethod: ctx.userAuthNMethod,
RequestMethod: ctx.requestMethod,
RequestURI: ctx.requestURI,
RequestBody: body,
RequestHeaders: headers(r.Header),
}
for _, plugin := range ctx.plugins {
logrus.Debugf("AuthZ request using plugin %s", plugin.Name())
authRes, err := plugin.AuthZRequest(ctx.authReq)
if err != nil {
return fmt.Errorf("plugin %s failed with error: %s", plugin.Name(), err)
}
if !authRes.Allow {
return fmt.Errorf("authorization denied by plugin %s: %s", plugin.Name(), authRes.Msg)
}
}
return nil
}
// AuthZResponse authorized and manipulates the response from docker daemon using authZ plugins
func (ctx *Ctx) AuthZResponse(rm ResponseModifier, r *http.Request) error {
ctx.authReq.ResponseStatusCode = rm.StatusCode()
ctx.authReq.ResponseHeaders = headers(rm.Header())
if sendBody(ctx.requestURI, rm.Header()) {
ctx.authReq.ResponseBody = rm.RawBody()
}
for _, plugin := range ctx.plugins {
logrus.Debugf("AuthZ response using plugin %s", plugin.Name())
authRes, err := plugin.AuthZResponse(ctx.authReq)
if err != nil {
return fmt.Errorf("plugin %s failed with error: %s", plugin.Name(), err)
}
if !authRes.Allow {
return fmt.Errorf("authorization denied by plugin %s: %s", plugin.Name(), authRes.Msg)
}
}
rm.FlushAll()
return nil
}
// drainBody dump the body (if it's length is less than 1MB) without modifying the request state
func drainBody(body io.ReadCloser) ([]byte, io.ReadCloser, error) {
bufReader := bufio.NewReaderSize(body, maxBodySize)
newBody := ioutils.NewReadCloserWrapper(bufReader, func() error { return body.Close() })
data, err := bufReader.Peek(maxBodySize)
// Body size exceeds max body size
if err == nil {
logrus.Warnf("Request body is larger than: '%d' skipping body", maxBodySize)
return nil, newBody, nil
}
// Body size is less than maximum size
if err == io.EOF {
return data, newBody, nil
}
// Unknown error
return nil, newBody, err
}
// sendBody returns true when request/response body should be sent to AuthZPlugin
func sendBody(url string, header http.Header) bool {
// Skip body for auth endpoint
if strings.HasSuffix(url, "/auth") {
return false
}
// body is sent only for text or json messages
return header.Get("Content-Type") == "application/json"
}
// headers returns flatten version of the http headers excluding authorization
func headers(header http.Header) map[string]string {
v := make(map[string]string, 0)
for k, values := range header {
// Skip authorization headers
if strings.EqualFold(k, "Authorization") || strings.EqualFold(k, "X-Registry-Config") || strings.EqualFold(k, "X-Registry-Auth") {
continue
}
for _, val := range values {
v[k] = val
}
}
return v
}