From patchwork Wed Jul 31 22:15:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11069641 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EB0EB912 for ; Wed, 31 Jul 2019 22:16:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DB84227F17 for ; Wed, 31 Jul 2019 22:16:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D023B27F94; Wed, 31 Jul 2019 22:16:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5F21C27F17 for ; Wed, 31 Jul 2019 22:16:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731175AbfGaWQi (ORCPT ); Wed, 31 Jul 2019 18:16:38 -0400 Received: from mail-pg1-f201.google.com ([209.85.215.201]:51462 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731169AbfGaWQh (ORCPT ); Wed, 31 Jul 2019 18:16:37 -0400 Received: by mail-pg1-f201.google.com with SMTP id p15so132947pgl.18 for ; Wed, 31 Jul 2019 15:16:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=u2905WeoBzsTcUqrWVSX7p6zMJ6qFdPBK2S0ptkFjO4=; b=u51IK7rm5PXjX+fuzwbwKYHh7z82TiYvcoisKg+mw4dPfi537EDtpJlHb76TtTHgFv vjevqlCVpTIEf22kAsMGnz4NvYb86Gl3aaZQ7/L505uG3YhegqctpP0VO697Qg91mgDg M5ywjgGoguWLtgYdI+0kwbkbWSgDaSrnCP43WUSkiaX1YlO/EkbVGJb/RMkgPpF7PFaZ p3DxrCKXrxnUKluUrp0ln4c4E06Efrj/BhiYxtBNH5VKYSkQOpVg8FFhnIreEfA/8oNd cAnWttGxFRdm5bq72j2e42G36uPkg9YEYwn/BC3539tTHq4v3L8llkrFCJNdd0ZPP/PK VYaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=u2905WeoBzsTcUqrWVSX7p6zMJ6qFdPBK2S0ptkFjO4=; b=A2PSWaXFSTxir2RGIJYi2FMbonzKMmS8R5CYUHSLtKoHrpiZLnSeA1fm/TCmFe7Nw+ SyQ4Gx+pe5TEAsJ2neZHP6tWC8XocEI0H4iOV/5+WdDEiFKB0xCenwsHBiZEJDR6w8UB t87x6Y6XjNeDjPVwi5T5t8LkIfX6xLRhk4+l1fVke3LdOUlZH4VqX7xa+E5cV5jobuYQ PmR74EOHoVaBQDfpq7JlXyWcD+3S1PZd1ideMiaUdkyVmYQ9z+yfyQkI2fOqvStHaSf2 OdOVRNXE3x52eWGGiyU1o8fE5mWWvWJPLdWKpXiubA/8VoOsvrJF31wuWvuO/l2pwzLC oHzQ== X-Gm-Message-State: APjAAAWKP7DF3nK66uOAghm1J8J41rbFqv8LubYgPEdTtYclDRE1r3ou ZcVNmaa+8u8Lm4wc+W+zNH/kx/XUQUf0sc7m5bG8eA== X-Google-Smtp-Source: APXvYqz9nvN6pLViGUJfhDU7XrmbV1ThI84+OES+YdosYp86dZSWqyXpxYB8/pHdM0JLrTFBZ3J3PT7o5Op4B7wSckVznA== X-Received: by 2002:a63:b20f:: with SMTP id x15mr6925516pge.453.1564611396278; Wed, 31 Jul 2019 15:16:36 -0700 (PDT) Date: Wed, 31 Jul 2019 15:15:52 -0700 In-Reply-To: <20190731221617.234725-1-matthewgarrett@google.com> Message-Id: <20190731221617.234725-5-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190731221617.234725-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.770.g0f2c4a37fd-goog Subject: [PATCH V37 04/29] Enforce module signatures if the kernel is locked down From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Matthew Garrett , Kees Cook , Jessica Yu Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: David Howells If the kernel is locked down, require that all modules have valid signatures that we can verify. I have adjusted the errors generated: (1) If there's no signature (ENODATA) or we can't check it (ENOPKG, ENOKEY), then: (a) If signatures are enforced then EKEYREJECTED is returned. (b) If there's no signature or we can't check it, but the kernel is locked down then EPERM is returned (this is then consistent with other lockdown cases). (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we return the error we got. Note that the X.509 code doesn't check for key expiry as the RTC might not be valid or might not have been transferred to the kernel's clock yet. [Modified by Matthew Garrett to remove the IMA integration. This will be replaced with integration with the IMA architecture policy patchset.] Signed-off-by: David Howells Signed-off-by: Matthew Garrett Reviewed-by: Kees Cook Cc: Jessica Yu --- include/linux/security.h | 1 + kernel/module.c | 37 +++++++++++++++++++++++++++++------- security/lockdown/lockdown.c | 1 + 3 files changed, 32 insertions(+), 7 deletions(-) diff --git a/include/linux/security.h b/include/linux/security.h index 54a0532ec12f..8e70063074a1 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -103,6 +103,7 @@ enum lsm_event { */ enum lockdown_reason { LOCKDOWN_NONE, + LOCKDOWN_MODULE_SIGNATURE, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/module.c b/kernel/module.c index cd8df516666d..318209889e26 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2771,8 +2771,9 @@ static inline void kmemleak_load_module(const struct module *mod, #ifdef CONFIG_MODULE_SIG static int module_sig_check(struct load_info *info, int flags) { - int err = -ENOKEY; + int err = -ENODATA; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const char *reason; const void *mod = info->hdr; /* @@ -2787,16 +2788,38 @@ static int module_sig_check(struct load_info *info, int flags) err = mod_verify_sig(mod, info); } - if (!err) { + switch (err) { + case 0: info->sig_ok = true; return 0; - } - /* Not having a signature is only an error if we're strict. */ - if (err == -ENOKEY && !is_module_sig_enforced()) - err = 0; + /* We don't permit modules to be loaded into trusted kernels + * without a valid signature on them, but if we're not + * enforcing, certain errors are non-fatal. + */ + case -ENODATA: + reason = "Loading of unsigned module"; + goto decide; + case -ENOPKG: + reason = "Loading of module with unsupported crypto"; + goto decide; + case -ENOKEY: + reason = "Loading of module with unavailable key"; + decide: + if (is_module_sig_enforced()) { + pr_notice("%s is rejected\n", reason); + return -EKEYREJECTED; + } - return err; + return security_locked_down(LOCKDOWN_MODULE_SIGNATURE); + + /* All other errors are fatal, including nomem, unparseable + * signatures and signature check failures - even if signatures + * aren't required. + */ + default: + return err; + } } #else /* !CONFIG_MODULE_SIG */ static int module_sig_check(struct load_info *info, int flags) diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index d30c4d254b5f..2c53fd9f5c9b 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -18,6 +18,7 @@ static enum lockdown_reason kernel_locked_down; static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_NONE] = "none", + [LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };