From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E7DDEC873A for ; Thu, 7 Sep 2023 15:30:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235529AbjIGP2y (ORCPT ); Thu, 7 Sep 2023 11:28:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235297AbjIGPW6 (ORCPT ); Thu, 7 Sep 2023 11:22:58 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A363172E for ; Thu, 7 Sep 2023 08:22:41 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD7FCC4DE17; Thu, 7 Sep 2023 15:04:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694099094; bh=sXaG813F0m1dgQHl1cDGt+KmXjJhKGQtyH0fQs1Adpg=; h=Subject:To:Cc:From:Date:From; b=Gk38QfQjPGlXNaCTqoFKaO/u20+7+7h98DSKgK1I/tNBHtX9AlynqrM9ibKdbCPq9 HBXgKik3MOXDtz5yu1+hdBj0twSyq9ZdyTAkQawZ0gsDcCg+A0a/vLkGGmdWLN4Qy2 QqoPfgFHVX0uC0XKArVNRpSyzGzXMk9hHKBDWUOM= Subject: FAILED: patch "[PATCH] memfd: do not -EACCES old memfd_create() users with" failed to apply to 6.4-stable tree To: cyphar@cyphar.com, akpm@linux-foundation.org, asmadeus@codewreck.org, brauner@kernel.org, dverkamp@chromium.org, jeffxu@google.com, keescook@chromium.org, shuah@kernel.org, stable@vger.kernel.org Cc: From: Date: Thu, 07 Sep 2023 16:04:47 +0100 Message-ID: <2023090747-scant-detest-aeed@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 6.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.4.y git checkout FETCH_HEAD git cherry-pick -x 202e14222fadb246dfdf182e67de1518e86a1e20 # git commit -s git send-email --to '' --in-reply-to '2023090747-scant-detest-aeed@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^.. Possible dependencies: 202e14222fad ("memfd: do not -EACCES old memfd_create() users with vm.memfd_noexec=2") badbbcd76545 ("selftests/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED") 72de25913022 ("mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 202e14222fadb246dfdf182e67de1518e86a1e20 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Mon, 14 Aug 2023 18:40:58 +1000 Subject: [PATCH] memfd: do not -EACCES old memfd_create() users with vm.memfd_noexec=2 Given the difficulty of auditing all of userspace to figure out whether every memfd_create() user has switched to passing MFD_EXEC and MFD_NOEXEC_SEAL flags, it seems far less distruptive to make it possible for older programs that don't make use of executable memfds to run under vm.memfd_noexec=2. Otherwise, a small dependency change can result in spurious errors. For programs that don't use executable memfds, passing MFD_NOEXEC_SEAL is functionally a no-op and thus having the same In addition, every failure under vm.memfd_noexec=2 needs to print to the kernel log so that userspace can figure out where the error came from. The concerns about pr_warn_ratelimited() spam that caused the switch to pr_warn_once()[1,2] do not apply to the vm.memfd_noexec=2 case. This is a user-visible API change, but as it allows programs to do something that would be blocked before, and the sysctl itself was broken and recently released, it seems unlikely this will cause any issues. [1]: https://lore.kernel.org/Y5yS8wCnuYGLHMj4@x1n/ [2]: https://lore.kernel.org/202212161233.85C9783FB@keescook/ Link: https://lkml.kernel.org/r/20230814-memfd-vm-noexec-uapi-fixes-v2-2-7ff9e3e10ba6@cyphar.com Fixes: 105ff5339f49 ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") Signed-off-by: Aleksa Sarai Cc: Dominique Martinet Cc: Christian Brauner Cc: Daniel Verkamp Cc: Jeff Xu Cc: Kees Cook Cc: Shuah Khan Cc: Signed-off-by: Andrew Morton diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index c758809d5bcf..53974d79d98e 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -17,18 +17,10 @@ struct fs_pin; #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE) -/* - * sysctl for vm.memfd_noexec - * 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL - * acts like MFD_EXEC was set. - * 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL - * acts like MFD_NOEXEC_SEAL was set. - * 2: memfd_create() without MFD_NOEXEC_SEAL will be - * rejected. - */ -#define MEMFD_NOEXEC_SCOPE_EXEC 0 -#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL 1 -#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED 2 +/* modes for vm.memfd_noexec sysctl */ +#define MEMFD_NOEXEC_SCOPE_EXEC 0 /* MFD_EXEC implied if unset */ +#define MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL 1 /* MFD_NOEXEC_SEAL implied if unset */ +#define MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED 2 /* same as 1, except MFD_EXEC rejected */ #endif struct pid_namespace { diff --git a/mm/memfd.c b/mm/memfd.c index 0bdbd2335af7..d65485c762de 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -271,30 +271,22 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg) static int check_sysctl_memfd_noexec(unsigned int *flags) { #ifdef CONFIG_SYSCTL - char comm[TASK_COMM_LEN]; - int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; - struct pid_namespace *ns; - - ns = task_active_pid_ns(current); - if (ns) - sysctl = ns->memfd_noexec_scope; + int sysctl = task_active_pid_ns(current)->memfd_noexec_scope; if (!(*flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) { - if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) + if (sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) *flags |= MFD_NOEXEC_SEAL; else *flags |= MFD_EXEC; } - if (*flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { - pr_warn_once( - "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n", - task_pid_nr(current), get_task_comm(comm, current)); - + if (!(*flags & MFD_NOEXEC_SEAL) && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { + pr_err_ratelimited( + "%s[%d]: memfd_create() requires MFD_NOEXEC_SEAL with vm.memfd_noexec=%d\n", + current->comm, task_pid_nr(current), sysctl); return -EACCES; } #endif - return 0; } @@ -302,7 +294,6 @@ SYSCALL_DEFINE2(memfd_create, const char __user *, uname, unsigned int, flags) { - char comm[TASK_COMM_LEN]; unsigned int *file_seals; struct file *file; int fd, error; @@ -325,12 +316,13 @@ SYSCALL_DEFINE2(memfd_create, if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) { pr_warn_once( - "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", - task_pid_nr(current), get_task_comm(comm, current)); + "%s[%d]: memfd_create() called without MFD_EXEC or MFD_NOEXEC_SEAL set\n", + current->comm, task_pid_nr(current)); } - if (check_sysctl_memfd_noexec(&flags) < 0) - return -EACCES; + error = check_sysctl_memfd_noexec(&flags); + if (error < 0) + return error; /* length includes terminating zero */ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1); diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 8eb49204f9ea..8b7390ad81d1 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -1145,11 +1145,23 @@ static void test_sysctl_child(void) printf("%s sysctl 2\n", memfd_str); sysctl_assert_write("2"); - mfd_fail_new("kern_memfd_sysctl_2", - MFD_CLOEXEC | MFD_ALLOW_SEALING); - mfd_fail_new("kern_memfd_sysctl_2_MFD_EXEC", - MFD_CLOEXEC | MFD_EXEC); - fd = mfd_assert_new("", 0, MFD_NOEXEC_SEAL); + mfd_fail_new("kern_memfd_sysctl_2_exec", + MFD_EXEC | MFD_CLOEXEC | MFD_ALLOW_SEALING); + + fd = mfd_assert_new("kern_memfd_sysctl_2_dfl", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_mode(fd, 0666); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_fail_chmod(fd, 0777); + close(fd); + + fd = mfd_assert_new("kern_memfd_sysctl_2_noexec_seal", + mfd_def_size, + MFD_NOEXEC_SEAL | MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_mode(fd, 0666); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_fail_chmod(fd, 0777); close(fd); sysctl_fail_write("0");