From patchwork Tue Mar 21 20:15:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ackerley Tng X-Patchwork-Id: 13183234 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 E87FAC761AF for ; Tue, 21 Mar 2023 20:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230054AbjCUUQC (ORCPT ); Tue, 21 Mar 2023 16:16:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229550AbjCUUQA (ORCPT ); Tue, 21 Mar 2023 16:16:00 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 048FB584B9 for ; Tue, 21 Mar 2023 13:15:45 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id ml17-20020a17090b361100b0023f9e99ab95so3257643pjb.1 for ; Tue, 21 Mar 2023 13:15:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679429744; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=SASYwsYhAQSqNIE6HUln5R808O00UDaM+ugmJxC1i6Y=; b=nkDLVeFOEtNHIk2/9xYa/CQ5Y+2ViSmqdwKS37RKpN9fN1MXmDMz1OU9puFW4g8bxR vii0vfViksMKRckdTjgGuQRIZo78lhmcmIzghCZBBHxvW/ndiQpVU4djvbvM+g/7wUMs +h4BMeKpfniUSkYQ2+iXYK1OzQ6Zixd18XxuCFovZYEJjKkL+JZVoFx8wgMxsnNIhhrW cwAnxft2O57Rn97HBOHm6iE115uNcFbAUa0j/WlnnPQnSn42zEaUa3fkNCQ6d75oG0jY i+hqkZSaarDOufSFczQvwQKpFfhRDRSFIn/93xiAf3T7ZrsK4NycMXJEfB2VVpheLbup 9TAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679429744; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=SASYwsYhAQSqNIE6HUln5R808O00UDaM+ugmJxC1i6Y=; b=0kO9umujenhVLJExuiQY8ZlllG15Xf5Yn2kzzUiO6yEj9sxOfcOsB8WZu4pBNzkZGw q414avnpP+NEgVLBSQgWdyOAZP5uEqhen0e56caYjAl/lcM8u5PYWHcqLSalrHmaThGw ePymjvl5OB3KNZMlNy+vzN2MY90FX5ygxSSYBkpR2GdLeaVGgdFl9JnR7I9QBjKVTXq2 q/ckG5yUQIz/IUyitMLnXZDAxMbuLPqcnFMDnsWmcvIAfl9kXZ1gYxl9UTgLZOBb2tL7 ClB7kk9C/axFbCcrSBSGVv6tTh4mTf4qwfI5SQlZowtpTRMjTNAmaq6kLbCv90B+AJkO 1SGw== X-Gm-Message-State: AO0yUKXTZ+XtlcuFdNCFCpsmVnL+y4UoswLhLeGCfcszFNgYDofl921u BPebMRShLOOtRQfvDFYyPwWy4OH0i9WBUYS1ZT3k4sIu5y/ObmbUehkxcmVUjvW5w6ea0VGYWIT eZBT7gkxwTcFF4I+RVh4H4SKlfOdu+dL5ZBmYm0QK0MjrQs/8hkMZN/kxmuugD50cfs8Cv1Y= X-Google-Smtp-Source: AK7set/HvJzxMftd1uCLemfdr7EZh/avv/uPbf4VraKazWicqnhqmpj6db9AHljzqSRdUL4ivIO6IsbGNBTLA3WbfA== X-Received: from ackerleytng-cloudtop.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1f5f]) (user=ackerleytng job=sendgmr) by 2002:a17:902:b612:b0:1a0:51f7:7f5a with SMTP id b18-20020a170902b61200b001a051f77f5amr137446pls.13.1679429744410; Tue, 21 Mar 2023 13:15:44 -0700 (PDT) Date: Tue, 21 Mar 2023 20:15:32 +0000 In-Reply-To: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.40.0.rc2.332.ga46443480c-goog Message-ID: <6e800e069c7fc400841b75ea49d1227bd101c1cf.1679428901.git.ackerleytng@google.com> Subject: [RFC PATCH v2 1/2] mm: restrictedmem: Allow userspace to specify mount for memfd_restricted From: Ackerley Tng To: kvm@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org Cc: aarcange@redhat.com, ak@linux.intel.com, akpm@linux-foundation.org, arnd@arndb.de, bfields@fieldses.org, bp@alien8.de, chao.p.peng@linux.intel.com, corbet@lwn.net, dave.hansen@intel.com, david@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, hpa@zytor.com, hughd@google.com, jlayton@kernel.org, jmattson@google.com, joro@8bytes.org, jun.nakajima@intel.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, luto@kernel.org, mail@maciej.szmigiero.name, mhocko@suse.com, michael.roth@amd.com, mingo@redhat.com, naoya.horiguchi@nec.com, pbonzini@redhat.com, qperret@google.com, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, tabba@google.com, tglx@linutronix.de, vannapurve@google.com, vbabka@suse.cz, vkuznets@redhat.com, wanpengli@tencent.com, wei.w.wang@intel.com, x86@kernel.org, yu.c.zhang@linux.intel.com, Ackerley Tng Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org By default, the backing shmem file for a restrictedmem fd is created on shmem's kernel space mount. With this patch, an optional tmpfs mount can be specified via an fd, which will be used as the mountpoint for backing the shmem file associated with a restrictedmem fd. This change is modeled after how sys_open() can create an unnamed temporary file in a given directory with O_TMPFILE. This will help restrictedmem fds inherit the properties of the provided tmpfs mounts, for example, hugepage allocation hints, NUMA binding hints, etc. Signed-off-by: Ackerley Tng --- include/linux/syscalls.h | 2 +- include/uapi/linux/restrictedmem.h | 8 ++++ mm/restrictedmem.c | 63 +++++++++++++++++++++++++++--- 3 files changed, 66 insertions(+), 7 deletions(-) create mode 100644 include/uapi/linux/restrictedmem.h diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index f9e9e0c820c5..a23c4c385cd3 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1056,7 +1056,7 @@ asmlinkage long sys_memfd_secret(unsigned int flags); asmlinkage long sys_set_mempolicy_home_node(unsigned long start, unsigned long len, unsigned long home_node, unsigned long flags); -asmlinkage long sys_memfd_restricted(unsigned int flags); +asmlinkage long sys_memfd_restricted(unsigned int flags, int mount_fd); /* * Architecture-specific system calls diff --git a/include/uapi/linux/restrictedmem.h b/include/uapi/linux/restrictedmem.h new file mode 100644 index 000000000000..9f108dd1ac4c --- /dev/null +++ b/include/uapi/linux/restrictedmem.h @@ -0,0 +1,8 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_RESTRICTEDMEM_H +#define _UAPI_LINUX_RESTRICTEDMEM_H + +/* flags for memfd_restricted */ +#define RMFD_TMPFILE 0x0001U + +#endif /* _UAPI_LINUX_RESTRICTEDMEM_H */ diff --git a/mm/restrictedmem.c b/mm/restrictedmem.c index c5d869d8c2d8..4d83b949d84e 100644 --- a/mm/restrictedmem.c +++ b/mm/restrictedmem.c @@ -1,11 +1,12 @@ // SPDX-License-Identifier: GPL-2.0 -#include "linux/sbitmap.h" +#include #include #include #include #include #include #include +#include #include struct restrictedmem { @@ -189,19 +190,20 @@ static struct file *restrictedmem_file_create(struct file *memfd) return file; } -SYSCALL_DEFINE1(memfd_restricted, unsigned int, flags) +static int restrictedmem_create(struct vfsmount *mount) { struct file *file, *restricted_file; int fd, err; - if (flags) - return -EINVAL; - fd = get_unused_fd_flags(0); if (fd < 0) return fd; - file = shmem_file_setup("memfd:restrictedmem", 0, VM_NORESERVE); + if (mount) + file = shmem_file_setup_with_mnt(mount, "memfd:restrictedmem", 0, VM_NORESERVE); + else + file = shmem_file_setup("memfd:restrictedmem", 0, VM_NORESERVE); + if (IS_ERR(file)) { err = PTR_ERR(file); goto err_fd; @@ -223,6 +225,55 @@ SYSCALL_DEFINE1(memfd_restricted, unsigned int, flags) return err; } +static bool is_shmem_mount(struct vfsmount *mnt) +{ + return mnt && mnt->mnt_sb && mnt->mnt_sb->s_magic == TMPFS_MAGIC; +} + +static int restrictedmem_create_from_file(int mount_fd) +{ + int ret; + struct fd f; + struct vfsmount *mnt; + + f = fdget_raw(mount_fd); + if (!f.file) + return -EBADF; + + mnt = f.file->f_path.mnt; + if (!is_shmem_mount(mnt)) { + ret = -EINVAL; + goto out; + } + + ret = mnt_want_write(mnt); + if (unlikely(ret)) + goto out; + + ret = restrictedmem_create(mnt); + + mnt_drop_write(mnt); +out: + fdput(f); + + return ret; +} + +SYSCALL_DEFINE2(memfd_restricted, unsigned int, flags, int, mount_fd) +{ + if (flags & ~RMFD_TMPFILE) + return -EINVAL; + + if (flags == RMFD_TMPFILE) { + if (mount_fd < 0) + return -EINVAL; + + return restrictedmem_create_from_file(mount_fd); + } else { + return restrictedmem_create(NULL); + } +} + int restrictedmem_bind(struct file *file, pgoff_t start, pgoff_t end, struct restrictedmem_notifier *notifier, bool exclusive) {