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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1E753C433EF for ; Wed, 16 Feb 2022 21:07:10 +0000 (UTC) Received: from localhost ([::1]:33270 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nKRW0-00075Z-PB for qemu-devel@archiver.kernel.org; Wed, 16 Feb 2022 16:07:08 -0500 Received: from eggs.gnu.org ([209.51.188.92]:45716) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKRVE-0006P0-Ez for qemu-devel@nongnu.org; Wed, 16 Feb 2022 16:06:21 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:28205) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKRV1-0003EC-Ta for qemu-devel@nongnu.org; Wed, 16 Feb 2022 16:06:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645045567; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=p0RnlFfzQJySKna15p7Z+trT0H+KlpUfL2SBl+TisD0=; b=UiJRtvpZDNLRJvprFI/94GKaoIrLbnaASNu/XMbiepuq4rhNMxZZkQCGmEsAYAT8d8KNOF K/Acv5mrwyS+7KWhCXDacs644GFS6oaSAZSg1drcacB3ky1tB/oGURgVCKfx5YkXbvqJzU 9YzKSrhSNENIc61176dc+nSZFY1GOq4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-389-VhYkumGQN3Wuhe0m9EfH8Q-1; Wed, 16 Feb 2022 16:06:03 -0500 X-MC-Unique: VhYkumGQN3Wuhe0m9EfH8Q-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7111F1006AA5; Wed, 16 Feb 2022 21:06:02 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.16.187]) by smtp.corp.redhat.com (Postfix) with ESMTP id CAF92610A7; Wed, 16 Feb 2022 21:05:24 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 5574B22361A; Wed, 16 Feb 2022 16:05:24 -0500 (EST) Date: Wed, 16 Feb 2022 16:05:24 -0500 From: Vivek Goyal To: "Dr. David Alan Gilbert" Subject: Re: [Virtio-fs] [PULL 00/12] virtiofs queue Message-ID: References: <20220216173625.128109-1-dgilbert@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vgoyal@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, sebastian.hasler@stuvus.uni-stuttgart.de, qemu-devel@nongnu.org, groug@kaod.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Feb 16, 2022 at 07:40:14PM +0000, Dr. David Alan Gilbert wrote: > * Dr. David Alan Gilbert (git) (dgilbert@redhat.com) wrote: > > From: "Dr. David Alan Gilbert" > > > > The following changes since commit c13b8e9973635f34f3ce4356af27a311c993729c: > > > > Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20220216' into staging (2022-02-16 09:57:11 +0000) > > > > are available in the Git repository at: > > > > https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20220216 > > > > for you to fetch changes up to 47cc3ef597b2ee926c13c9433f4f73645429e128: > > > > virtiofsd: Add basic support for FUSE_SYNCFS request (2022-02-16 17:29:32 +0000) > > NAK > this doesn't build on older Linuxes. > > Rework version in the works. Hi David, I think it is patch 8 which is using gettid(). I have updated that patch and now I am using syscall(NR_gettid) instead. Here is the updated patch. I hope this solves the build on older Linux issue. Subject: virtiofsd: Add helpers to work with /proc/self/task/tid/attr/fscreate Soon we will be able to create and also set security context on the file atomically using /proc/self/task/tid/attr/fscreate knob. If this knob is available on the system, first set the knob with the desired context and then create the file. It will be created with the context set in fscreate. This works basically for SELinux and its per thread. This patch just introduces the helper functions. Subsequent patches will make use of these helpers. Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Vivek Goyal --- tools/virtiofsd/passthrough_ll.c | 92 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) Index: rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c =================================================================== --- rhvgoyal-qemu.orig/tools/virtiofsd/passthrough_ll.c 2022-02-16 15:53:13.657015138 -0500 +++ rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c 2022-02-16 15:55:14.911234993 -0500 @@ -173,10 +173,14 @@ struct lo_data { /* An O_PATH file descriptor to /proc/self/fd/ */ int proc_self_fd; + /* An O_PATH file descriptor to /proc/self/task/ */ + int proc_self_task; int user_killpriv_v2, killpriv_v2; /* If set, virtiofsd is responsible for setting umask during creation */ bool change_umask; int user_posix_acl, posix_acl; + /* Keeps track if /proc//attr/fscreate should be used or not */ + bool use_fscreate; }; static const struct fuse_opt lo_opts[] = { @@ -257,6 +261,72 @@ static struct lo_data *lo_data(fuse_req_ } /* + * Tries to figure out if /proc//attr/fscreate is usable or not. With + * selinux=0, read from fscreate returns -EINVAL. + * + * TODO: Link with libselinux and use is_selinux_enabled() instead down + * the line. It probably will be more reliable indicator. + */ +static bool is_fscreate_usable(struct lo_data *lo) +{ + char procname[64]; + int fscreate_fd; + size_t bytes_read; + + sprintf(procname, "%ld/attr/fscreate", syscall(SYS_gettid)); + fscreate_fd = openat(lo->proc_self_task, procname, O_RDWR); + if (fscreate_fd == -1) { + return false; + } + + bytes_read = read(fscreate_fd, procname, 64); + close(fscreate_fd); + if (bytes_read == -1) { + return false; + } + return true; +} + +/* Helpers to set/reset fscreate */ +__attribute__((unused)) +static int open_set_proc_fscreate(struct lo_data *lo, const void *ctx, + size_t ctxlen,int *fd) +{ + char procname[64]; + int fscreate_fd, err = 0; + size_t written; + + sprintf(procname, "%ld/attr/fscreate", syscall(SYS_gettid)); + fscreate_fd = openat(lo->proc_self_task, procname, O_WRONLY); + err = fscreate_fd == -1 ? errno : 0; + if (err) { + return err; + } + + written = write(fscreate_fd, ctx, ctxlen); + err = written == -1 ? errno : 0; + if (err) { + goto out; + } + + *fd = fscreate_fd; + return 0; +out: + close(fscreate_fd); + return err; +} + +__attribute__((unused)) +static void close_reset_proc_fscreate(int fd) +{ + if ((write(fd, NULL, 0)) == -1) { + fuse_log(FUSE_LOG_WARNING, "Failed to reset fscreate. err=%d\n", errno); + } + close(fd); + return; +} + +/* * Load capng's state from our saved state if the current thread * hadn't previously been loaded. * returns 0 on success @@ -3522,6 +3592,15 @@ static void setup_namespaces(struct lo_d exit(1); } + /* Get the /proc/self/task descriptor */ + lo->proc_self_task = open("/proc/self/task/", O_PATH); + if (lo->proc_self_task == -1) { + fuse_log(FUSE_LOG_ERR, "open(/proc/self/task, O_PATH): %m\n"); + exit(1); + } + + lo->use_fscreate = is_fscreate_usable(lo); + /* * We only need /proc/self/fd. Prevent ".." from accessing parent * directories of /proc/self/fd by bind-mounting it over /proc. Since / was @@ -3738,6 +3817,14 @@ static void setup_chroot(struct lo_data exit(1); } + lo->proc_self_task = open("/proc/self/task", O_PATH); + if (lo->proc_self_fd == -1) { + fuse_log(FUSE_LOG_ERR, "open(\"/proc/self/task\", O_PATH): %m\n"); + exit(1); + } + + lo->use_fscreate = is_fscreate_usable(lo); + /* * Make the shared directory the file system root so that FUSE_OPEN * (lo_open()) cannot escape the shared directory by opening a symlink. @@ -3923,6 +4010,10 @@ static void fuse_lo_data_cleanup(struct close(lo->proc_self_fd); } + if (lo->proc_self_task >= 0) { + close(lo->proc_self_task); + } + if (lo->root.fd >= 0) { close(lo->root.fd); } @@ -3950,6 +4041,7 @@ int main(int argc, char *argv[]) .posix_lock = 0, .allow_direct_io = 0, .proc_self_fd = -1, + .proc_self_task = -1, .user_killpriv_v2 = -1, .user_posix_acl = -1, };