fix: enforce content type header for API requests (argoproj#16860)

Signed-off-by: Alexander Matyushentsev <AMatyushentsev@gmail.com>

cmd/argocd-server/commands/argocd_server.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"math"
+	"strings"
 	"time"
 
 	"github.com/argoproj/pkg/stats"
@@ -63,6 +64,7 @@ func NewCommand() *cobra.Command {
 		repoServerAddress        string
 		dexServerAddress         string
 		disableAuth              bool
+		contentTypes             string
 		enableGZip               bool
 		tlsConfigCustomizerSrc   func() (tls.ConfigCustomizer, error)
 		cacheSrc                 func() (*servercache.Cache, error)
@@ -185,6 +187,7 @@ func NewCommand() *cobra.Command {
 				DexServerAddr:         dexServerAddress,
 				DexTLSConfig:          dexTlsConfig,
 				DisableAuth:           disableAuth,
+				ContentTypes:          strings.Split(contentTypes, ";"),
 				EnableGZip:            enableGZip,
 				TLSConfigCustomizer:   tlsConfigCustomizer,
 				Cache:                 cache,
@@ -240,6 +243,7 @@ func NewCommand() *cobra.Command {
 	command.Flags().StringVar(&repoServerAddress, "repo-server", env.StringFromEnv("ARGOCD_SERVER_REPO_SERVER", common.DefaultRepoServerAddr), "Repo server address")
 	command.Flags().StringVar(&dexServerAddress, "dex-server", env.StringFromEnv("ARGOCD_SERVER_DEX_SERVER", common.DefaultDexServerAddr), "Dex server address")
 	command.Flags().BoolVar(&disableAuth, "disable-auth", env.ParseBoolFromEnv("ARGOCD_SERVER_DISABLE_AUTH", false), "Disable client authentication")
+	command.Flags().StringVar(&contentTypes, "api-content-types", "application/json", "Semicolon separated list of allowed content types for non GET api requests. Any content type is allowed if empty.")
 	command.Flags().BoolVar(&enableGZip, "enable-gzip", env.ParseBoolFromEnv("ARGOCD_SERVER_ENABLE_GZIP", true), "Enable GZIP compression")
 	command.AddCommand(cli.NewVersionCmd(cliName))
 	command.Flags().StringVar(&listenHost, "address", env.StringFromEnv("ARGOCD_SERVER_LISTEN_ADDRESS", common.DefaultAddressAPIServer), "Listen on given address")

docs/operator-manual/server-commands/argocd-server.md

@@ -26,6 +26,7 @@ argocd-server [flags]
 
 ```
       --address string                                  Listen on given address (default "0.0.0.0")
+      --api-content-types string                        Semicolon separated list of allowed content types for non GET api requests. Any content type is allowed if empty. (default "application/json")
       --app-state-cache-expiration duration             Cache expiration for app state (default 1h0m0s)
       --application-namespaces strings                  List of additional namespaces where application resources can be managed in
       --as string                                       Username to impersonate for the operation

server/server.go

@@ -197,6 +197,7 @@ type ArgoCDServer struct {
 
 type ArgoCDServerOpts struct {
 	DisableAuth           bool
+	ContentTypes          []string
 	EnableGZip            bool
 	Insecure              bool
 	StaticAssetsDir       string
@@ -990,6 +991,9 @@ func (a *ArgoCDServer) newHTTPServer(ctx context.Context, port int, grpcWebHandl
 	if a.EnableGZip {
 		handler = compressHandler(handler)
 	}
+	if len(a.ContentTypes) > 0 {
+		handler = enforceContentTypes(handler, a.ContentTypes)
+	}
 	mux.Handle("/api/", handler)
 
 	terminal := application.NewHandler(a.appLister, a.Namespace, a.ApplicationNamespaces, a.db, a.enf, a.Cache, appResourceTreeFn, a.settings.ExecShells, *a.sessionMgr).
@@ -1056,6 +1060,20 @@ func (a *ArgoCDServer) newHTTPServer(ctx context.Context, port int, grpcWebHandl
 	return &httpS
 }
 
+func enforceContentTypes(handler http.Handler, types []string) http.Handler {
+	allowedTypes := map[string]bool{}
+	for _, t := range types {
+		allowedTypes[strings.ToLower(t)] = true
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet || allowedTypes[strings.ToLower(r.Header.Get("Content-Type"))] {
+			handler.ServeHTTP(w, r)
+		} else {
+			http.Error(w, "Invalid content type", http.StatusUnsupportedMediaType)
+		}
+	})
+}
+
 // registerExtensions will try to register all configured extensions
 // in the given mux. If any error is returned while registering
 // extensions handlers, no route will be added in the given mux.

test/e2e/fixture/http.go

@@ -28,6 +28,7 @@ func DoHttpRequest(method string, path string, data ...byte) (*http.Response, er
 		return nil, err
 	}
 	req.AddCookie(&http.Cookie{Name: common.AuthCookieName, Value: token})
+	req.Header.Set("Content-Type", "application/json")
 
 	httpClient := &http.Client{
 		Transport: &http.Transport{