From patchwork Thu Jan 11 02:03:10 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10156687 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 4F20A60231 for ; Thu, 11 Jan 2018 02:20:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 38BA128610 for ; Thu, 11 Jan 2018 02:20:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2B15D2874E; Thu, 11 Jan 2018 02:20:10 +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 8479D28750 for ; Thu, 11 Jan 2018 02:20:08 +0000 (UTC) Received: (qmail 28462 invoked by uid 550); 11 Jan 2018 02:19:50 -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 28359 invoked from network); 11 Jan 2018 02:19:47 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Yad3saplUftFxuPbHofhJ+Ufy/cN7DOhySZODO/JXZY=; b=mYYq0dJC0C1YnU4vQcdgoFk8NIYshhBDnIIeUgZDMgylx+yx+1p+mFPU1Y4cx7MEu3 RQtm0oeHVjeQidif5JKLxiE3/6DCeDlI0cc2vc5h+B2JyCSMSukj0T9FUvYZmgTBvjfe yfaacDFaZI83C4csRm4mtARJJgkWI/tmjcvcU= 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=Yad3saplUftFxuPbHofhJ+Ufy/cN7DOhySZODO/JXZY=; b=NvpFW/85KV5S2hOEbedMBGGjpIrcPTTdfaLtPeQQ3QQpD25CeOq7N12/oax1BhTyXf ZYgYceFvZWCnl/m2ZQ+WAhODKcas3HIv5N5G6X4CddIH4o/J9F1O+1KJ/Q19OgzMWjAi jUomdCoWNjza0qoxbMBF497Q45Xq/+eZ8X202QXOn141u+GEdwZR6fOroFWXBZVXhSvd wdf0ewEVPv4p1BRTWfM7Uu3+amcRQNAAkxki1QQ8OZLzUV9nXTTxkYiwRvZbbJnpCyp6 CmzVuizEMsh/N1ZFhegCvARXQrJ3UwUzr/fStr5ahQ4S2/uUQAR1+JnyKqbkD21RD0b9 Nx+Q== X-Gm-Message-State: AKGB3mJzo05+5Sl0VSVmmWuV6I3ZZOWfb5amBwI0Gq0DWvkHmTYgvTmp o8mDNcJlXLa5KGtxz8nM2K0toQ== X-Google-Smtp-Source: ACJfBouvFWemq3F6CkN0CpToIoTkqd9mG66+vEfNtGAFNDoVzFwRDY3ipn+eF76YvjFq7AGCCf8m2Q== X-Received: by 10.101.80.74 with SMTP id k10mr16242125pgo.418.1515637175619; Wed, 10 Jan 2018 18:19:35 -0800 (PST) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Linus Torvalds , David Windsor , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Date: Wed, 10 Jan 2018 18:03:10 -0800 Message-Id: <1515636190-24061-39-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515636190-24061-1-git-send-email-keescook@chromium.org> References: <1515636190-24061-1-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] [PATCH 38/38] lkdtm: Update usercopy tests for whitelisting X-Virus-Scanned: ClamAV using ClamSMTP This updates the USERCOPY_HEAP_FLAG_* tests to USERCOPY_HEAP_WHITELIST_*, since the final form of usercopy whitelisting ended up using an offset/size window instead of the earlier proposed allocation flags. Signed-off-by: Kees Cook --- drivers/misc/lkdtm.h | 4 +- drivers/misc/lkdtm_core.c | 4 +- drivers/misc/lkdtm_usercopy.c | 88 ++++++++++++++++++++++++------------------- 3 files changed, 53 insertions(+), 43 deletions(-) diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h index 687a0dbbe199..9e513dcfd809 100644 --- a/drivers/misc/lkdtm.h +++ b/drivers/misc/lkdtm.h @@ -76,8 +76,8 @@ void __init lkdtm_usercopy_init(void); void __exit lkdtm_usercopy_exit(void); void lkdtm_USERCOPY_HEAP_SIZE_TO(void); void lkdtm_USERCOPY_HEAP_SIZE_FROM(void); -void lkdtm_USERCOPY_HEAP_FLAG_TO(void); -void lkdtm_USERCOPY_HEAP_FLAG_FROM(void); +void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void); +void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void); void lkdtm_USERCOPY_STACK_FRAME_TO(void); void lkdtm_USERCOPY_STACK_FRAME_FROM(void); void lkdtm_USERCOPY_STACK_BEYOND(void); diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index ba92291508dc..e3f2bac4b245 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -177,8 +177,8 @@ static const struct crashtype crashtypes[] = { CRASHTYPE(ATOMIC_TIMING), CRASHTYPE(USERCOPY_HEAP_SIZE_TO), CRASHTYPE(USERCOPY_HEAP_SIZE_FROM), - CRASHTYPE(USERCOPY_HEAP_FLAG_TO), - CRASHTYPE(USERCOPY_HEAP_FLAG_FROM), + CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO), + CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM), CRASHTYPE(USERCOPY_STACK_FRAME_TO), CRASHTYPE(USERCOPY_STACK_FRAME_FROM), CRASHTYPE(USERCOPY_STACK_BEYOND), diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c index 9ebbb031e5e3..9725aed305bb 100644 --- a/drivers/misc/lkdtm_usercopy.c +++ b/drivers/misc/lkdtm_usercopy.c @@ -20,7 +20,7 @@ */ static volatile size_t unconst = 0; static volatile size_t cache_size = 1024; -static struct kmem_cache *bad_cache; +static struct kmem_cache *whitelist_cache; static const unsigned char test_text[] = "This is a test.\n"; @@ -115,6 +115,10 @@ static noinline void do_usercopy_stack(bool to_user, bool bad_frame) vm_munmap(user_addr, PAGE_SIZE); } +/* + * This checks for whole-object size validation with hardened usercopy, + * with or without usercopy whitelisting. + */ static void do_usercopy_heap_size(bool to_user) { unsigned long user_addr; @@ -177,77 +181,79 @@ static void do_usercopy_heap_size(bool to_user) kfree(two); } -static void do_usercopy_heap_flag(bool to_user) +/* + * This checks for the specific whitelist window within an object. If this + * test passes, then do_usercopy_heap_size() tests will pass too. + */ +static void do_usercopy_heap_whitelist(bool to_user) { - unsigned long user_addr; - unsigned char *good_buf = NULL; - unsigned char *bad_buf = NULL; + unsigned long user_alloc; + unsigned char *buf = NULL; + unsigned char __user *user_addr; + size_t offset, size; /* Make sure cache was prepared. */ - if (!bad_cache) { + if (!whitelist_cache) { pr_warn("Failed to allocate kernel cache\n"); return; } /* - * Allocate one buffer from each cache (kmalloc will have the - * SLAB_USERCOPY flag already, but "bad_cache" won't). + * Allocate a buffer with a whitelisted window in the buffer. */ - good_buf = kmalloc(cache_size, GFP_KERNEL); - bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL); - if (!good_buf || !bad_buf) { - pr_warn("Failed to allocate buffers from caches\n"); + buf = kmem_cache_alloc(whitelist_cache, GFP_KERNEL); + if (!buf) { + pr_warn("Failed to allocate buffer from whitelist cache\n"); goto free_alloc; } /* Allocate user memory we'll poke at. */ - user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + user_alloc = vm_mmap(NULL, 0, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (user_addr >= TASK_SIZE) { + if (user_alloc >= TASK_SIZE) { pr_warn("Failed to allocate user memory\n"); goto free_alloc; } + user_addr = (void __user *)user_alloc; - memset(good_buf, 'A', cache_size); - memset(bad_buf, 'B', cache_size); + memset(buf, 'B', cache_size); + + /* Whitelisted window in buffer, from kmem_cache_create_usercopy. */ + offset = (cache_size / 4) + unconst; + size = (cache_size / 16) + unconst; if (to_user) { - pr_info("attempting good copy_to_user with SLAB_USERCOPY\n"); - if (copy_to_user((void __user *)user_addr, good_buf, - cache_size)) { + pr_info("attempting good copy_to_user inside whitelist\n"); + if (copy_to_user(user_addr, buf + offset, size)) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } - pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n"); - if (copy_to_user((void __user *)user_addr, bad_buf, - cache_size)) { + pr_info("attempting bad copy_to_user outside whitelist\n"); + if (copy_to_user(user_addr, buf + offset - 1, size)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } } else { - pr_info("attempting good copy_from_user with SLAB_USERCOPY\n"); - if (copy_from_user(good_buf, (void __user *)user_addr, - cache_size)) { + pr_info("attempting good copy_from_user inside whitelist\n"); + if (copy_from_user(buf + offset, user_addr, size)) { pr_warn("copy_from_user failed unexpectedly?!\n"); goto free_user; } - pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n"); - if (copy_from_user(bad_buf, (void __user *)user_addr, - cache_size)) { + pr_info("attempting bad copy_from_user outside whitelist\n"); + if (copy_from_user(buf + offset - 1, user_addr, size)) { pr_warn("copy_from_user failed, but lacked Oops\n"); goto free_user; } } free_user: - vm_munmap(user_addr, PAGE_SIZE); + vm_munmap(user_alloc, PAGE_SIZE); free_alloc: - if (bad_buf) - kmem_cache_free(bad_cache, bad_buf); - kfree(good_buf); + if (buf) + kmem_cache_free(whitelist_cache, buf); } /* Callable tests. */ @@ -261,14 +267,14 @@ void lkdtm_USERCOPY_HEAP_SIZE_FROM(void) do_usercopy_heap_size(false); } -void lkdtm_USERCOPY_HEAP_FLAG_TO(void) +void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void) { - do_usercopy_heap_flag(true); + do_usercopy_heap_whitelist(true); } -void lkdtm_USERCOPY_HEAP_FLAG_FROM(void) +void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void) { - do_usercopy_heap_flag(false); + do_usercopy_heap_whitelist(false); } void lkdtm_USERCOPY_STACK_FRAME_TO(void) @@ -319,11 +325,15 @@ void lkdtm_USERCOPY_KERNEL(void) void __init lkdtm_usercopy_init(void) { /* Prepare cache that lacks SLAB_USERCOPY flag. */ - bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0, - 0, NULL); + whitelist_cache = + kmem_cache_create_usercopy("lkdtm-usercopy", cache_size, + 0, 0, + cache_size / 4, + cache_size / 16, + NULL); } void __exit lkdtm_usercopy_exit(void) { - kmem_cache_destroy(bad_cache); + kmem_cache_destroy(whitelist_cache); }