[JENKINS-73422] Add escape hatch for Authenticated user access to Resource URL (jenkinsci#9644)

Co-authored-by: Daniel Beck <[email protected]>

Author: Dohbedoh

core/src/main/java/jenkins/security/ResourceDomainRootAction.java

@@ -117,7 +117,7 @@ public Object getDynamic(String id, StaplerRequest req, StaplerResponse rsp) thr
             return null;
         }
 
-        if (!ACL.isAnonymous2(Jenkins.getAuthentication2())) {
+        if (!ALLOW_AUTHENTICATED_USER && !ACL.isAnonymous2(Jenkins.getAuthentication2())) {
             rsp.sendError(400);
             return null;
         }
@@ -327,4 +327,8 @@ private static Token decode(String value) {
     // Not @Restricted because the entire class is
     @SuppressFBWarnings(value = "MS_SHOULD_BE_FINAL", justification = "for script console")
     public static /* not final for Groovy */ int VALID_FOR_MINUTES = SystemProperties.getInteger(ResourceDomainRootAction.class.getName() + ".validForMinutes", 30);
+
+    /* Escape hatch for a security hardening preventing one of the known ways to elevate arbitrary file read to RCE */
+    @SuppressFBWarnings(value = "MS_SHOULD_BE_FINAL", justification = "for script console")
+    public static /* not final for Groovy */ boolean ALLOW_AUTHENTICATED_USER = SystemProperties.getBoolean(ResourceDomainRootAction.class.getName() + ".allowAuthenticatedUser", false);
 }

test/src/test/java/jenkins/security/ResourceDomainTest.java

@@ -399,7 +399,7 @@ public HttpResponse doDynamic() throws Exception {
     }
 
     @Test
-    public void authenticatedCannotAccessResourceDomain() throws Exception {
+    public void authenticatedCannotAccessResourceDomainUnlessAllowedBySystemProperty() throws Exception {
         j.jenkins.setSecurityRealm(j.createDummySecurityRealm());
         final MockAuthorizationStrategy authorizationStrategy = new MockAuthorizationStrategy();
         authorizationStrategy.grant(Jenkins.ADMINISTER).everywhere().to("admin").grant(Jenkins.READ).everywhere().toEveryone();
@@ -416,5 +416,13 @@ public void authenticatedCannotAccessResourceDomain() throws Exception {
         try (JenkinsRule.WebClient wc = j.createWebClient().withBasicCredentials("admin")) {
             assertThat(assertThrows(FailingHttpStatusCodeException.class, () -> wc.getPage(new URL(resourceUrl))).getStatusCode(), is(400));
         }
+
+        ResourceDomainRootAction.ALLOW_AUTHENTICATED_USER = true;
+        try (JenkinsRule.WebClient wc = j.createWebClient().withBasicApiToken("admin")) {
+            assertThat(wc.getPage(new URL(resourceUrl)).getWebResponse().getStatusCode(), is(200));
+        }
+        try (JenkinsRule.WebClient wc = j.createWebClient().withBasicCredentials("admin")) {
+            assertThat(wc.getPage(new URL(resourceUrl)).getWebResponse().getStatusCode(), is(200));
+        }
     }
 }