From patchwork Wed Sep 27 19:50:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 9974655 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EC9AF603F2 for ; Wed, 27 Sep 2017 19:53:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF0B328ECA for ; Wed, 27 Sep 2017 19:53:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D3B8A2930D; Wed, 27 Sep 2017 19:53:12 +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=-6.3 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, T_DKIM_INVALID autolearn=unavailable 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 8338E29315 for ; Wed, 27 Sep 2017 19:53:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751649AbdI0TwC (ORCPT ); Wed, 27 Sep 2017 15:52:02 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:38587 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751768AbdI0TvS (ORCPT ); Wed, 27 Sep 2017 15:51:18 -0400 Received: by mail-pf0-f194.google.com with SMTP id a7so7590852pfj.5; Wed, 27 Sep 2017 12:51:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=T9WGfjgE+1Sv6o87bA6zR5RBrXsZxzgDM/EtcZyEy6M=; b=bnNE0yMruP4ifcBBk13MHPwqcR+E8DqpqiKQBfODFvkoPXpxHoF2iFHYCeo4d1x5X5 6xxtfpLLyMwFWLNyJoqcdJKxrI7lXbUlZvH4IqtQH1hiU8h6HEh5i4gGv7fFn+jDypLP 9+Rsg0zs9wXyzDFCUK5R7Atj68RLH6tESabk2/77NlgkziK0InrS7yhHgxpQoxhChSRc Ui1fVzbMcyiDxdu7gOhRBfbSHZnl6RHek3BjX0XwVg1U0AVJaF4eY/VlPVhunC1Lu03e nbCoOyi9x0C5fVjGHFO+MdLx2b2GEgbNePefsTbiW8dK85t8LeAQOsMCP1HxaFXjm3+f MiTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=T9WGfjgE+1Sv6o87bA6zR5RBrXsZxzgDM/EtcZyEy6M=; b=ZQz8RUqRlDhiWezjt/O7FmOOQIjQCl8olsOA2WAnEey/fq1Nv2SNrv5NBXd97A4d+v MNJVWmgOOPYjCoVOSat/HIHAVM4mLLIfZzYMNBRr1te9wzEFrYIauUtAjavTlB97s9p9 Sqk/4ezCZiH1acxmLJUYnifRFSf/XHX35Vnz8zqh0F7dKeiaTdHxIBebOU7qmOL5aQpW GKPV2iB1etV8sO0/3+eHBk8tMioJFpnOfKYfbU6XnnUFk8uL4cpK0REMbQkQVdL6Dqcl E8Mmlrli7YTzBuE7YCB7jQ5a+3Ojci0H0oHoTK/lb9r49k4nfoJnOzLmFbMQxJgGf58C ulRw== X-Gm-Message-State: AHPjjUjWJkSge838oDtH7N+fmxo7tEAyY67aLNnKD5AoSiu8NHsQ4ww3 9dccMDgsLLURVDPzCcPzHUK3XtKs X-Google-Smtp-Source: AOwi7QDsT9+40MQjAkK5cypa9YNhyfNS2sHj7ufEWwJhOw0mVhmmBeQZow5XOPW9g3P3Oatjfc6vVw== X-Received: by 10.99.126.87 with SMTP id o23mr2150145pgn.277.1506541877467; Wed, 27 Sep 2017 12:51:17 -0700 (PDT) Received: from ebiggers-linuxstation.kir.corp.google.com ([100.66.174.81]) by smtp.gmail.com with ESMTPSA id d5sm24954499pfg.26.2017.09.27.12.51.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 27 Sep 2017 12:51:16 -0700 (PDT) From: Eric Biggers To: keyrings@vger.kernel.org Cc: David Howells , Michael Halcrow , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Eric Biggers Subject: [PATCH v3 6/7] KEYS: load key flags and expiry time atomically in proc_keys_show() Date: Wed, 27 Sep 2017 12:50:46 -0700 Message-Id: <20170927195047.122358-7-ebiggers3@gmail.com> X-Mailer: git-send-email 2.14.2.822.g60be5d43e6-goog In-Reply-To: <20170927195047.122358-1-ebiggers3@gmail.com> References: <20170927195047.122358-1-ebiggers3@gmail.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers In proc_keys_show(), the key semaphore is not held, so the key ->flags and ->expiry can be changed concurrently. We therefore should read them atomically just once. Otherwise /proc/keys may show an inconsistent state, such a key that is negative ('N') but not instantiated ('I'). Signed-off-by: Eric Biggers --- security/keys/proc.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/security/keys/proc.c b/security/keys/proc.c index de834309d100..a038069ac46a 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -179,7 +179,9 @@ static int proc_keys_show(struct seq_file *m, void *v) struct rb_node *_p = v; struct key *key = rb_entry(_p, struct key, serial_node); struct timespec now; + time_t expiry; unsigned long timo; + unsigned long flags; key_ref_t key_ref, skey_ref; char xbuf[16]; int rc; @@ -217,12 +219,13 @@ static int proc_keys_show(struct seq_file *m, void *v) rcu_read_lock(); /* come up with a suitable timeout value */ - if (key->expiry == 0) { + expiry = READ_ONCE(key->expiry); + if (expiry == 0) { memcpy(xbuf, "perm", 5); - } else if (now.tv_sec >= key->expiry) { + } else if (now.tv_sec >= expiry) { memcpy(xbuf, "expd", 5); } else { - timo = key->expiry - now.tv_sec; + timo = expiry - now.tv_sec; if (timo < 60) sprintf(xbuf, "%lus", timo); @@ -236,18 +239,19 @@ static int proc_keys_show(struct seq_file *m, void *v) sprintf(xbuf, "%luw", timo / (60*60*24*7)); } -#define showflag(KEY, LETTER, FLAG) \ - (test_bit(FLAG, &(KEY)->flags) ? LETTER : '-') +#define showflag(FLAGS, LETTER, FLAG) \ + ((FLAGS & (1 << FLAG)) ? LETTER : '-') + flags = READ_ONCE(key->flags); seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ", key->serial, - showflag(key, 'I', KEY_FLAG_INSTANTIATED), - showflag(key, 'R', KEY_FLAG_REVOKED), - showflag(key, 'D', KEY_FLAG_DEAD), - showflag(key, 'Q', KEY_FLAG_IN_QUOTA), - showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT), - showflag(key, 'N', KEY_FLAG_NEGATIVE), - showflag(key, 'i', KEY_FLAG_INVALIDATED), + showflag(flags, 'I', KEY_FLAG_INSTANTIATED), + showflag(flags, 'R', KEY_FLAG_REVOKED), + showflag(flags, 'D', KEY_FLAG_DEAD), + showflag(flags, 'Q', KEY_FLAG_IN_QUOTA), + showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT), + showflag(flags, 'N', KEY_FLAG_NEGATIVE), + showflag(flags, 'i', KEY_FLAG_INVALIDATED), refcount_read(&key->usage), xbuf, key->perm,