From patchwork Tue Oct 13 14:06:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Giuseppe Scrivano X-Patchwork-Id: 11835887 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 E25CCA829 for ; Tue, 13 Oct 2020 18:11:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D923247B8 for ; Tue, 13 Oct 2020 14:06:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C4g3fhac" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388294AbgJMOGa (ORCPT ); Tue, 13 Oct 2020 10:06:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:33652 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388236AbgJMOG0 (ORCPT ); Tue, 13 Oct 2020 10:06:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602597985; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5qT8jquoQOvD8a7SF5l/rxB3mSNwZ5S4wf/Z1Ex1Krk=; b=C4g3fhac4/EUbQRJFosbmEcUMu6QtoiCvjATzMu4MtjFkweEvgX8otLmwrsgQt1pVsBbXm yekwKhym70O/kfc2BfKHiNXuJeHHlndbEO83GvngH+77eHQaaI446RV6zYJbBId54IQqJJ ocakZvhV6JCniMcK8NcGRsXbtfJSnbI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-166-XJGwe52cPvKPEYN1yPVNBg-1; Tue, 13 Oct 2020 10:06:23 -0400 X-MC-Unique: XJGwe52cPvKPEYN1yPVNBg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0DDD5805722; Tue, 13 Oct 2020 14:06:22 +0000 (UTC) Received: from lithium.redhat.com (ovpn-112-43.ams2.redhat.com [10.36.112.43]) by smtp.corp.redhat.com (Postfix) with ESMTP id 77A015C1C2; Tue, 13 Oct 2020 14:06:20 +0000 (UTC) From: Giuseppe Scrivano To: linux-kernel@vger.kernel.org Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, christian.brauner@ubuntu.com, containers@lists.linux-foundation.org Subject: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC Date: Tue, 13 Oct 2020 16:06:08 +0200 Message-Id: <20201013140609.2269319-2-gscrivan@redhat.com> In-Reply-To: <20201013140609.2269319-1-gscrivan@redhat.com> References: <20201013140609.2269319-1-gscrivan@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't immediately close the files but it sets the close-on-exec bit. Signed-off-by: Giuseppe Scrivano --- fs/file.c | 56 ++++++++++++++++++++++---------- include/uapi/linux/close_range.h | 3 ++ 2 files changed, 42 insertions(+), 17 deletions(-) diff --git a/fs/file.c b/fs/file.c index 21c0893f2f1d..ad4ebee41e09 100644 --- a/fs/file.c +++ b/fs/file.c @@ -672,6 +672,17 @@ int __close_fd(struct files_struct *files, unsigned fd) } EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ +static unsigned int __get_max_fds(struct files_struct *cur_fds) +{ + unsigned int max_fds; + + rcu_read_lock(); + /* cap to last valid index into fdtable */ + max_fds = files_fdtable(cur_fds)->max_fds; + rcu_read_unlock(); + return max_fds; +} + /** * __close_range() - Close all file descriptors in a given range. * @@ -683,27 +694,23 @@ EXPORT_SYMBOL(__close_fd); /* for ksys_close() */ */ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) { - unsigned int cur_max; + unsigned int cur_max = UINT_MAX; struct task_struct *me = current; struct files_struct *cur_fds = me->files, *fds = NULL; - if (flags & ~CLOSE_RANGE_UNSHARE) + if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) return -EINVAL; if (fd > max_fd) return -EINVAL; - rcu_read_lock(); - cur_max = files_fdtable(cur_fds)->max_fds; - rcu_read_unlock(); - - /* cap to last valid index into fdtable */ - cur_max--; - if (flags & CLOSE_RANGE_UNSHARE) { int ret; unsigned int max_unshare_fds = NR_OPEN_MAX; + /* cap to last valid index into fdtable */ + cur_max = __get_max_fds(cur_fds) - 1; + /* * If the requested range is greater than the current maximum, * we're closing everything so only copy all file descriptors @@ -724,16 +731,31 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) swap(cur_fds, fds); } - max_fd = min(max_fd, cur_max); - while (fd <= max_fd) { - struct file *file; + if (flags & CLOSE_RANGE_CLOEXEC) { + struct fdtable *fdt; - file = pick_file(cur_fds, fd++); - if (!file) - continue; + spin_lock(&cur_fds->file_lock); + fdt = files_fdtable(cur_fds); + cur_max = fdt->max_fds - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) + __set_close_on_exec(fd++, fdt); + spin_unlock(&cur_fds->file_lock); + } else { + /* Initialize cur_max if needed. */ + if (cur_max == UINT_MAX) + cur_max = __get_max_fds(cur_fds) - 1; + max_fd = min(max_fd, cur_max); + while (fd <= max_fd) { + struct file *file; - filp_close(file, cur_fds); - cond_resched(); + file = pick_file(cur_fds, fd++); + if (!file) + continue; + + filp_close(file, cur_fds); + cond_resched(); + } } if (fds) { diff --git a/include/uapi/linux/close_range.h b/include/uapi/linux/close_range.h index 6928a9fdee3c..2d804281554c 100644 --- a/include/uapi/linux/close_range.h +++ b/include/uapi/linux/close_range.h @@ -5,5 +5,8 @@ /* Unshare the file descriptor table before closing file descriptors. */ #define CLOSE_RANGE_UNSHARE (1U << 1) +/* Set the FD_CLOEXEC bit instead of closing the file descriptor. */ +#define CLOSE_RANGE_CLOEXEC (1U << 2) + #endif /* _UAPI_LINUX_CLOSE_RANGE_H */