Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751869AbdGaXyW (ORCPT ); Mon, 31 Jul 2017 19:54:22 -0400 Received: from mail-pg0-f47.google.com ([74.125.83.47]:35819 "EHLO mail-pg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751800AbdGaXvw (ORCPT ); Mon, 31 Jul 2017 19:51:52 -0400 From: Kees Cook To: Andrew Morton Cc: Kees Cook , David Howells , "Eric W. Biederman" , John Johansen , "Serge E. Hallyn" , Paul Moore , Stephen Smalley , Casey Schaufler , Tetsuo Handa , James Morris , Andy Lutomirski , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 10/15] exec: Use secureexec for setting dumpability Date: Mon, 31 Jul 2017 16:51:28 -0700 Message-Id: <1501545093-56634-11-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1501545093-56634-1-git-send-email-keescook@chromium.org> References: <1501545093-56634-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1550 Lines: 38 The examination of "current" to decide dumpability is wrong. This was a check of and euid/uid (or egid/gid) mismatch in the existing process, not the newly created one. This appears to stretch back into even the "history.git" tree. Luckily, dumpability is later set in commit_creds(). In earlier kernel versions before creds existed, similar checks also existed late in the exec flow, covering up the mistake as far back as I could find. Note that because the commit_creds() check examines differences of euid, uid, egid, gid, and capabilities between the old and new creds, it would look like the setup_new_exec() dumpability test could be entirely removed. However, the secureexec test may cover a different set of tests (specific to the LSMs) than what commit_creds() checks for. So, fix this test to use secureexec (the removed euid tests are redundant to the commoncap secureexec checks now). Cc: David Howells Signed-off-by: Kees Cook Acked-by: Serge Hallyn --- fs/exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/exec.c b/fs/exec.c index f0e8d25eba9f..f9997ea6414e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1333,7 +1333,7 @@ void setup_new_exec(struct linux_binprm * bprm) current->sas_ss_sp = current->sas_ss_size = 0; - if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) + if (!bprm->secureexec) set_dumpable(current->mm, SUID_DUMP_USER); else set_dumpable(current->mm, suid_dumpable); -- 2.7.4