From patchwork Mon Feb 13 19:28:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9570711 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 9C846601E7 for ; Mon, 13 Feb 2017 19:29:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8A63F27F9E for ; Mon, 13 Feb 2017 19:29:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7BB5827FA6; Mon, 13 Feb 2017 19:29:39 +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=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 8FF3427F9E for ; Mon, 13 Feb 2017 19:29:37 +0000 (UTC) Received: (qmail 13494 invoked by uid 550); 13 Feb 2017 19:29:35 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 13455 invoked from network); 13 Feb 2017 19:29:33 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=RNqB5XImtjmtifW036C5ePGe8ZYBdz6/XR9/AEqm3qg=; b=RMvrZfPzaCxHfxS/EQSQuvxKuOw176o4EwFvHPoXKhzKxiLAmdrX/VBc+bQJSIfGUI 1ak6geuP8k3cRi/J8UeP4RsWCM6e492YyRnZz8JmrDY4EZKgTvvIR74yKW25Jc8ffROh Ken0yMCQh7+apyWef4Hwf6x8IW+nmZAUlNjAs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=RNqB5XImtjmtifW036C5ePGe8ZYBdz6/XR9/AEqm3qg=; b=Og6FJwlrhtPVFduva8o/efquGOLySSXr2JMny2rxuQwztx7ISIh6CmbZPPgXVkHa8z nXsaWY2xfdhujYCfVz7qwFAeJbrsX52gGJ757Iz6YGUkBno9mGZaZajtLW/iGaSZPQMb VMyE2nDD6k1Ko7ROSdnxZkh7TIw/TlR/mDS8TeGAwJbp28FdEGJ7Vaax9l/EWBISbbIN tfn1LZ0REgCsoL9x5BZmEORAcBuvsV81jQyN8XF8Fsv4QPY1njqyKVySeVoRwsvs88e4 cJ+5u59pPtNw3eu5AAqQgISb9C5LQ0PBvL+ShF3fDh/ZFwc7WNLAuGDLF1hpkaMZNWXe inFw== X-Gm-Message-State: AMke39niWk/AreQZNAuQH+hAjS0w22qf5i4PAyrkNVkOIHnmdP/Ed4DHlcEaOVpsIcwv+cRk X-Received: by 10.99.133.65 with SMTP id u62mr28582585pgd.70.1487014112008; Mon, 13 Feb 2017 11:28:32 -0800 (PST) Date: Mon, 13 Feb 2017 11:28:30 -0800 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: kernel-hardening@lists.openwall.com, Hoeun Ryu Message-ID: <20170213192830.GA3339@beast> MIME-Version: 1.0 Content-Disposition: inline Subject: [kernel-hardening] [PATCH] usercopy: Adjust tests to deal with SMAP/PAN X-Virus-Scanned: ClamAV using ClamSMTP Under SMAP/PAN/etc, we cannot write directly to userspace memory, so this rearranges the test bytes to get written through copy_to_user(). Additionally fixes a small memory leak on user memory allocation failure, and drops the bad copy_from_user() test that would trigger a memcpy() against userspace on failure. Signed-off-by: Kees Cook --- lib/test_user_copy.c | 45 ++++++++++++++++++++++++++++++++------------- 1 file changed, 32 insertions(+), 13 deletions(-) diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c index 54bd898e356f..ac3a60ba9331 100644 --- a/lib/test_user_copy.c +++ b/lib/test_user_copy.c @@ -49,8 +49,8 @@ static int __init test_user_copy_init(void) zerokmem = kzalloc(PAGE_SIZE * 2, GFP_KERNEL); if (!zerokmem) { - kfree(kmem); - return -ENOMEM; + ret = -ENOMEM; + goto out_kmem; } user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2, @@ -58,14 +58,16 @@ static int __init test_user_copy_init(void) MAP_ANONYMOUS | MAP_PRIVATE, 0); if (user_addr >= (unsigned long)(TASK_SIZE)) { pr_warn("Failed to allocate user memory\n"); - kfree(kmem); - return -ENOMEM; + ret = -ENOMEM; + goto out_zerokmem; } usermem = (char __user *)user_addr; bad_usermem = (char *)user_addr; - /* Legitimate usage: none of these should fail. */ + /* + * Legitimate usage: none of these copies should fail. + */ ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE), "legitimate copy_from_user failed"); ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE), @@ -75,36 +77,53 @@ static int __init test_user_copy_init(void) ret |= test(put_user(value, (unsigned long __user *)usermem), "legitimate put_user failed"); - /* Invalid usage: none of these should succeed. */ + /* + * Invalid usage: none of these copies should succeed. + */ + + /* Prepare kernel memory with check values. */ memset(kmem, 0x5A, PAGE_SIZE); + memset(kmem + PAGE_SIZE, 0x5B, PAGE_SIZE); + + /* Reject kernel-to-kernel copies through copy_from_user(). */ ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), PAGE_SIZE), "illegal all-kernel copy_from_user passed"); + + /* Destination half of buffer should have been zeroed. */ ret |= test(memcmp(zerokmem, kmem, PAGE_SIZE), "zeroing failure for illegal all-kernel copy_from_user"); - memset(bad_usermem, 0x5A, PAGE_SIZE); + +#if 0 + /* + * When running with SMAP/PAN/etc, this will Oops the kernel + * due to the zeroing of userspace memory on failure. This needs + * to be tested in LKDTM instead, since this test module does not + * expect to explode. + */ ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem, PAGE_SIZE), "illegal reversed copy_from_user passed"); - ret |= test(memcmp(zerokmem, bad_usermem, PAGE_SIZE), - "zeroing failure for illegal reversed copy_from_user"); +#endif ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE, PAGE_SIZE), "illegal all-kernel copy_to_user passed"); ret |= test(!copy_to_user((char __user *)kmem, bad_usermem, PAGE_SIZE), "illegal reversed copy_to_user passed"); - memset(kmem, 0x5A, PAGE_SIZE); + + value = 0x5A; ret |= test(!get_user(value, (unsigned long __user *)kmem), "illegal get_user passed"); - ret |= test(memcmp(zerokmem, kmem, sizeof(value)), - "zeroing failure for illegal get_user"); + ret |= test(value != 0, "zeroing failure for illegal get_user"); ret |= test(!put_user(value, (unsigned long __user *)kmem), "illegal put_user passed"); vm_munmap(user_addr, PAGE_SIZE * 2); - kfree(kmem); +out_zerokmem: kfree(zerokmem); +out_kmem: + kfree(kmem); if (ret == 0) { pr_info("tests passed.\n");