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[209.132.180.67]) by mx.google.com with ESMTP id q13si3187170pfh.162.2019.03.26.11.31.43; Tue, 26 Mar 2019 11:31:58 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=bA3dmIiF; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732586AbfCZS2F (ORCPT + 99 others); Tue, 26 Mar 2019 14:28:05 -0400 Received: from mail-oi1-f202.google.com ([209.85.167.202]:36074 "EHLO mail-oi1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732566AbfCZS2B (ORCPT ); Tue, 26 Mar 2019 14:28:01 -0400 Received: by mail-oi1-f202.google.com with SMTP id t66so5741538oie.3 for ; Tue, 26 Mar 2019 11:28:01 -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=fNnpo8lLzymZARu5UXrve26AL2A88YZO9HZRbBxOnPc=; b=bA3dmIiFcHRvOdKWWJyyAWFxpd0/eSw3KHIROhS1I9yokwsCzfmKaqf2p2y68VqWW/ vlpoVkko2s4T0hcqSYMOU+Pcj9KiiFB8r4MVvv23Z4PL1HYmVD0aMOI1DyIsqALq8Pb+ xMGOgj4XAA7JK6szCyO/HvwnUME6L00WvEEIuexfwS454lE90GHCMLcOXzmPyOuuGij5 Ecg3v1tSGWh7r3dyYdfuMXae9MtbkUTDYLO4ipHww1JcpLUO7xwp8vIc9kcixNO56mIh IoUbHw0PRwuDn3ud9o3XyiRofhdf9MR73HyKVnqYfuvGbIALzJx0UJ57RtLp+OwxaJrp RduA== 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=fNnpo8lLzymZARu5UXrve26AL2A88YZO9HZRbBxOnPc=; b=N2PH4j0qbUIX6cjHGl75ONhEs82VUjL0ZE2ioQZCpwYDvLygy4NP/InSRxhsX+RqdM NZfXGbYYHmG61E6YMN/mRlx5qw8eLcn67DOwuCYLaARAxJwrs9ooyOZ6jXwbbvOqT4Lo 2oxE8WPK08rBFzD6WyRqTNH6AiemDyYljx5Fc2W/iMXYJgoGjxgmiU4uFQDG1tp9k9nQ qtBzcP/sp29lPNbBr0jvFe/4KSgDtgV70tipCALKv6m0pSDgyPuOg99HT3/XC53+/DAz i2o3rCVHEj7GG5yGEeuxZcoBMlIykTo3G+rDn1DEOLd49TDVfU9NzoPzEvJTwfjpZZ7a msWg== X-Gm-Message-State: APjAAAXRJlm9ANciXanuFmH+lDo/AS6fz+EfQkt1zBI3xwC7kVQGSar8 bJC9PR1D1TxbbumYsDiedxKjxe6beSs6Sa7VkZCEdA== X-Received: by 2002:aca:dd0b:: with SMTP id u11mr16650482oig.24.1553624880468; Tue, 26 Mar 2019 11:28:00 -0700 (PDT) Date: Tue, 26 Mar 2019 11:27:18 -0700 In-Reply-To: <20190326182742.16950-1-matthewgarrett@google.com> Message-Id: <20190326182742.16950-3-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190326182742.16950-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH V31 02/25] 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, dhowells@redhat.com, linux-api@vger.kernel.org, luto@kernel.org, Matthew Garrett , Jessica Yu Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Jessica Yu --- kernel/module.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 2ad1b5239910..deea9d2763f8 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2767,8 +2767,9 @@ 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; /* @@ -2783,16 +2784,40 @@ 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; + if (kernel_is_locked_down(reason, LOCKDOWN_INTEGRITY)) + return -EPERM; + return 0; + + /* 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) -- 2.21.0.392.gf8f6787159e-goog