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 56A53C4167B for ; Mon, 4 Dec 2023 20:35:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346264AbjLDUfV (ORCPT ); Mon, 4 Dec 2023 15:35:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346159AbjLDUeq (ORCPT ); Mon, 4 Dec 2023 15:34:46 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 092F010E7 for ; Mon, 4 Dec 2023 12:34:10 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B9F7C433C9; Mon, 4 Dec 2023 20:34:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701722049; bh=AZ4e0D5QbPxg4VQmGNpyeeGH8zOTpO8U4j6t8+mlc7A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l99a2idxo/SxNB/eHg5Oc+EDrUuRYazP1E8z+8PLXGXeJhh30Xnp8tWgSdDP2vXZR vpiNZRsS40tQFqvbIaFV0bRnt2Mq+50idc7TtI+WpSuUJKQA2jHB4T0OAhnqTO5xde VBZmnh85D5i8uKW9WRAhIhPPb8xOx76/V6a9hwAd6OFANRPgWkmmnEKlqa5uwP2smK jF6ieXXtolxpYDQL/zsRAwC+7u+SQ5lgmRZ8rY7fs/LRQ4VQt722vulRzzeyqkMeOs 4fZWudypKVf9MZ6o1fhDuAP/q3LV2jiVVle/fP7IjT8XnjnP8J5TkJrCFaP3l1IyoG jfKv+qevrjtqA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jens Axboe , Jann Horn , Sasha Levin , io-uring@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 21/32] io_uring: use fget/fput consistently Date: Mon, 4 Dec 2023 15:32:41 -0500 Message-ID: <20231204203317.2092321-21-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231204203317.2092321-1-sashal@kernel.org> References: <20231204203317.2092321-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.4 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jens Axboe [ Upstream commit 73363c262d6a7d26063da96610f61baf69a70f7c ] Normally within a syscall it's fine to use fdget/fdput for grabbing a file from the file table, and it's fine within io_uring as well. We do that via io_uring_enter(2), io_uring_register(2), and then also for cancel which is invoked from the latter. io_uring cannot close its own file descriptors as that is explicitly rejected, and for the cancel side of things, the file itself is just used as a lookup cookie. However, it is more prudent to ensure that full references are always grabbed. For anything threaded, either explicitly in the application itself or through use of the io-wq worker threads, this is what happens anyway. Generalize it and use fget/fput throughout. Also see the below link for more details. Link: https://lore.kernel.org/io-uring/CAG48ez1htVSO3TqmrF8QcX2WFuYTRM-VZ_N10i-VZgbtg=NNqw@mail.gmail.com/ Suggested-by: Jann Horn Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/cancel.c | 11 ++++++----- io_uring/io_uring.c | 36 ++++++++++++++++++------------------ 2 files changed, 24 insertions(+), 23 deletions(-) diff --git a/io_uring/cancel.c b/io_uring/cancel.c index 7b23607cf4afd..a5d51471feebb 100644 --- a/io_uring/cancel.c +++ b/io_uring/cancel.c @@ -263,7 +263,7 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) }; ktime_t timeout = KTIME_MAX; struct io_uring_sync_cancel_reg sc; - struct fd f = { }; + struct file *file = NULL; DEFINE_WAIT(wait); int ret, i; @@ -285,10 +285,10 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) /* we can grab a normal file descriptor upfront */ if ((cd.flags & IORING_ASYNC_CANCEL_FD) && !(cd.flags & IORING_ASYNC_CANCEL_FD_FIXED)) { - f = fdget(sc.fd); - if (!f.file) + file = fget(sc.fd); + if (!file) return -EBADF; - cd.file = f.file; + cd.file = file; } ret = __io_sync_cancel(current->io_uring, &cd, sc.fd); @@ -338,6 +338,7 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) if (ret == -ENOENT || ret > 0) ret = 0; out: - fdput(f); + if (file) + fput(file); return ret; } diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 8d1bc6cdfe712..e27d970b140c3 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3603,7 +3603,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, size_t, argsz) { struct io_ring_ctx *ctx; - struct fd f; + struct file *file; long ret; if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP | @@ -3621,20 +3621,19 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX)) return -EINVAL; fd = array_index_nospec(fd, IO_RINGFD_REG_MAX); - f.file = tctx->registered_rings[fd]; - f.flags = 0; - if (unlikely(!f.file)) + file = tctx->registered_rings[fd]; + if (unlikely(!file)) return -EBADF; } else { - f = fdget(fd); - if (unlikely(!f.file)) + file = fget(fd); + if (unlikely(!file)) return -EBADF; ret = -EOPNOTSUPP; - if (unlikely(!io_is_uring_fops(f.file))) + if (unlikely(!io_is_uring_fops(file))) goto out; } - ctx = f.file->private_data; + ctx = file->private_data; ret = -EBADFD; if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED)) goto out; @@ -3728,7 +3727,8 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, } } out: - fdput(f); + if (!(flags & IORING_ENTER_REGISTERED_RING)) + fput(file); return ret; } @@ -4569,7 +4569,7 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode, { struct io_ring_ctx *ctx; long ret = -EBADF; - struct fd f; + struct file *file; bool use_registered_ring; use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING); @@ -4588,27 +4588,27 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode, if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX)) return -EINVAL; fd = array_index_nospec(fd, IO_RINGFD_REG_MAX); - f.file = tctx->registered_rings[fd]; - f.flags = 0; - if (unlikely(!f.file)) + file = tctx->registered_rings[fd]; + if (unlikely(!file)) return -EBADF; } else { - f = fdget(fd); - if (unlikely(!f.file)) + file = fget(fd); + if (unlikely(!file)) return -EBADF; ret = -EOPNOTSUPP; - if (!io_is_uring_fops(f.file)) + if (!io_is_uring_fops(file)) goto out_fput; } - ctx = f.file->private_data; + ctx = file->private_data; mutex_lock(&ctx->uring_lock); ret = __io_uring_register(ctx, opcode, arg, nr_args); mutex_unlock(&ctx->uring_lock); trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret); out_fput: - fdput(f); + if (!use_registered_ring) + fput(file); return ret; } -- 2.42.0