From patchwork Wed Mar 25 23:02:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Colascione X-Patchwork-Id: 11458889 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2A4D91805 for ; Wed, 25 Mar 2020 23:04:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A3232076A for ; Wed, 25 Mar 2020 23:04:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="i7ZOUHjb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727655AbgCYXEF (ORCPT ); Wed, 25 Mar 2020 19:04:05 -0400 Received: from mail-ua1-f74.google.com ([209.85.222.74]:38127 "EHLO mail-ua1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727452AbgCYXEE (ORCPT ); Wed, 25 Mar 2020 19:04:04 -0400 Received: by mail-ua1-f74.google.com with SMTP id t10so1569599uaj.5 for ; Wed, 25 Mar 2020 16:04:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=REBj1fgB1itW3afNpdBeCKHTfmMER4muP4nMI9CXCW4=; b=i7ZOUHjbFgVx+s0UVSJIf8vLWEPboaP6kvpQJDJL8TGrAnhcez44af9mv/98ocfWvE GYIilsL5kfd5pBocqpSxRvgmC6d4prkhqUf6/hAq0fzS9gyQBoAqZDnaDyj6BDqkos5n WMn3smxCXwJBxZUygM0ar+EiLI8WqAA2U3mNbN/HevW0K9j2aMdlG7sgml+Z1FphTgG5 Q5go7scoS9bb5Ql8ljMb2itbIVAq8j5ALe6yGzKx49cTmyrknkkLRIwiDaCfmn9uk5Ce ZepD2ALjcmb8yILx8yJS8mqMhxVHW2hUWj6XhS7YPWe15bEY6nCH1QAZ9aJIdW5/dKDh 2WUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=REBj1fgB1itW3afNpdBeCKHTfmMER4muP4nMI9CXCW4=; b=m3PYsclndsacdGge16tvJGtVqB0xbkLXVVrTATuKw1U1Fb3aYIWr9FqHVAt1xCy4bu TnIN/aULvz8RRxozWGEGCb2WEaj//gfd48cPYRihxLYwOZcM7fMRPMkBNva1A4Cvf51q SC1l+/em1100Rh3ds26r4Tlj5nhFS4zQsE/RKuafTIo+X0sfX6cxDlVU9mgZ8aBNMGgy GRh6guNNTENGfvpRHQ/X5X7HXiSYUkbSNK0eTfIn5YPrxqOIw1CejdudEL1YWFSIEoUO U9foHEl6qYqHJ3puMxaXfoIyWvLRMk/L1Gt8m7ittOZts/0Z79F/1XwlPAeZ60lsG5+r AbIg== X-Gm-Message-State: ANhLgQ0I1OQ8X9x797qYX6BkD5BW+tzPUkarPEg6fZh2vQsdFg7uRzHC yTBEf54rqU3Bwvq+CzhD5bIDKBnAUGg= X-Google-Smtp-Source: ADFU+vs7IQhEMaKxtqnr+moo0vZvstvYbRtR5UCcCU4RfI+0ZcWfHjbWDnDHCtb/iWz2nYKBCZvXwQ28Ff8= X-Received: by 2002:a1f:f884:: with SMTP id w126mr4386443vkh.41.1585177443359; Wed, 25 Mar 2020 16:04:03 -0700 (PDT) Date: Wed, 25 Mar 2020 16:02:49 -0700 In-Reply-To: <20200214032635.75434-1-dancol@google.com> Message-Id: <20200325230245.184786-4-dancol@google.com> Mime-Version: 1.0 References: <20200214032635.75434-1-dancol@google.com> X-Mailer: git-send-email 2.25.1.696.g5e7596f4ac-goog Subject: [PATCH v2 3/3] Wire UFFD up to SELinux From: Daniel Colascione To: timmurray@google.com, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, viro@zeniv.linux.org.uk, paul@paul-moore.com, nnk@google.com, sds@tycho.nsa.gov, lokeshgidra@google.com Cc: Daniel Colascione Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This change gives userfaultfd file descriptors a real security context, allowing policy to act on them. Signed-off-by: Daniel Colascione --- fs/userfaultfd.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 07b0f6e03849..78ff5d898733 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -76,6 +76,8 @@ struct userfaultfd_ctx { bool mmap_changing; /* mm with one ore more vmas attached to this userfaultfd_ctx */ struct mm_struct *mm; + /* The inode that owns this context --- not a strong reference. */ + const struct inode *owner; }; struct userfaultfd_fork_ctx { @@ -1014,14 +1016,18 @@ static __poll_t userfaultfd_poll(struct file *file, poll_table *wait) } } +static const struct file_operations userfaultfd_fops; + static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, struct userfaultfd_ctx *new, struct uffd_msg *msg) { int fd; - fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new, - O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS)); + fd = anon_inode_getfd_secure( + "[userfaultfd]", &userfaultfd_fops, new, + O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS), + ctx->owner); if (fd < 0) return fd; @@ -1918,7 +1924,7 @@ static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) } #endif -const struct file_operations userfaultfd_fops = { +static const struct file_operations userfaultfd_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = userfaultfd_show_fdinfo, #endif @@ -1943,6 +1949,7 @@ static void init_once_userfaultfd_ctx(void *mem) SYSCALL_DEFINE1(userfaultfd, int, flags) { + struct file *file; struct userfaultfd_ctx *ctx; int fd; @@ -1972,8 +1979,25 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) /* prevent the mm struct to be freed */ mmgrab(ctx->mm); - fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx, - O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); + file = anon_inode_getfile_secure( + "[userfaultfd]", &userfaultfd_fops, ctx, + O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS), + NULL); + if (IS_ERR(file)) { + fd = PTR_ERR(file); + goto out; + } + + fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC); + if (fd < 0) { + fput(file); + goto out; + } + + ctx->owner = file_inode(file); + fd_install(fd, file); + +out: if (fd < 0) { mmdrop(ctx->mm); kmem_cache_free(userfaultfd_ctx_cachep, ctx);