From patchwork Tue Mar 16 19:42:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 12143699 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E7DDC4321A for ; Tue, 16 Mar 2021 19:44:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E14B64E33 for ; Tue, 16 Mar 2021 19:44:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240535AbhCPToC (ORCPT ); Tue, 16 Mar 2021 15:44:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240529AbhCPTna (ORCPT ); Tue, 16 Mar 2021 15:43:30 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 769F1C06175F for ; Tue, 16 Mar 2021 12:43:29 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id kk2-20020a17090b4a02b02900c777aa746fso31677pjb.3 for ; Tue, 16 Mar 2021 12:43:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=S/6rupWKTyorGS3sxCouSuC4B76W02uh+glgFafNJ6k=; b=l+/Kjam5NvfeDfV+Yu8QrXWQSQcinlicuz+iAO3dFsBEhL7wOE2CVxMoAsbS86+ngI GW308Ao/qDz4jYifgdFeTpPhnKmBwPVvIlzz/KW/j682xfe13WAnfH3tHNtk0HNPBMIi saywqG7giRqW2aekzc3OTq8GvrLmmbth5nIYDxMRX8v0L+b7hT7ND0Ak8Xy+uDTYimAV eqXEYZHdOCYZw47U6Sn1RA0AS+qrbOZk61GncN7N6sd9ayRuNHqBxX4CeuUD1Jkgq3MA mdEuncYZwRjPwlxv55956ASrh4zpV72GcKbMXmBISJ1fz1oWVeq7oPM1hvFaG3n29ooh 1DBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=S/6rupWKTyorGS3sxCouSuC4B76W02uh+glgFafNJ6k=; b=cq5wcoO5QS+OavMEbxTmxcToiyAeQl+J02z5MWo/1JnZ3tJJUowGQ2punN7vqpLaoj AsnUnqTgvdTVdNe88rsmL4u/HsybJiemk8ooE996p8BhTR7xmHwCZaE63mrx0pzc0hxQ iyHY1sT7nNekuai/WJ/nuZn3SGvPwTi2hIhlO1yHsBFWvTvjK4yi2Df1s1G5n1nEje87 6Yb67Ppflq21HV43YxopG69TywZWSl1LcRSn4ZDQjQIJ3+/5ov2pFRP7raoLOhnuomwE 9uzr3ad/dZklwOGqa2jdST0vdv9slkSBms9KK7SsUTvantq1Vw7AF3XwIwQPzyrmi6HO Dpnw== X-Gm-Message-State: AOAM530UpQCNN+XPIlQ+GQj2JTHJEDJxjF2m+jHF/MA5hcN1Z3u1P79e 8ttkaKt3SqaWV9UE3grIpPb6tQ== X-Google-Smtp-Source: ABdhPJyiKRF0IUPmE2h2K3CQBqvwez2zLaKR9/UVEtIqMTg95vIuBi3aGfn8wYzj9wThanJy/XMI7Q== X-Received: by 2002:a17:90a:fe93:: with SMTP id co19mr647555pjb.142.1615923808981; Tue, 16 Mar 2021 12:43:28 -0700 (PDT) Received: from relinquished.tfbnw.net ([2620:10d:c090:400::5:532]) by smtp.gmail.com with ESMTPSA id gm10sm217264pjb.4.2021.03.16.12.43.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 12:43:27 -0700 (PDT) From: Omar Sandoval To: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, Al Viro , Christoph Hellwig Cc: Dave Chinner , Jann Horn , Amir Goldstein , Aleksa Sarai , linux-api@vger.kernel.org, kernel-team@fb.com Subject: [PATCH v8 01/10] iov_iter: add copy_struct_from_iter() Date: Tue, 16 Mar 2021 12:42:57 -0700 Message-Id: X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Omar Sandoval This is essentially copy_struct_from_user() but for an iov_iter. Suggested-by: Aleksa Sarai Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval --- include/linux/uio.h | 2 ++ lib/iov_iter.c | 82 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+) diff --git a/include/linux/uio.h b/include/linux/uio.h index 72d88566694e..f4e6ea85a269 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -121,6 +121,8 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i, + size_t usize); size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); diff --git a/lib/iov_iter.c b/lib/iov_iter.c index a21e6a5792c5..f45826ed7528 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -948,6 +948,88 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, } EXPORT_SYMBOL(copy_page_from_iter); +/** + * copy_struct_from_iter - copy a struct from an iov_iter + * @dst: Destination buffer. + * @ksize: Size of @dst struct. + * @i: Source iterator. + * @usize: (Alleged) size of struct in @i. + * + * Copies a struct from an iov_iter in a way that guarantees + * backwards-compatibility for struct arguments in an iovec (as long as the + * rules for copy_struct_from_user() are followed). + * + * The recommended usage is that @usize be taken from the current segment: + * + * int do_foo(struct iov_iter *i) + * { + * size_t usize = iov_iter_single_seg_count(i); + * struct foo karg; + * int err; + * + * if (usize > PAGE_SIZE) + * return -E2BIG; + * if (usize < FOO_SIZE_VER0) + * return -EINVAL; + * err = copy_struct_from_iter(&karg, sizeof(karg), i, usize); + * if (err) + * return err; + * + * // ... + * } + * + * Return: 0 on success, -errno on error (see copy_struct_from_user()). + * + * On success, the iterator is advanced @usize bytes. On error, the iterator is + * not advanced. + */ +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i, + size_t usize) +{ + if (usize <= ksize) { + if (!copy_from_iter_full(dst, usize, i)) + return -EFAULT; + memset(dst + usize, 0, ksize - usize); + } else { + size_t copied = 0, copy; + int ret; + + if (WARN_ON(iov_iter_is_pipe(i)) || unlikely(i->count < usize)) + return -EFAULT; + if (iter_is_iovec(i)) + might_fault(); + iterate_all_kinds(i, usize, v, ({ + copy = min(ksize - copied, v.iov_len); + if (copy && copyin(dst + copied, v.iov_base, copy)) + return -EFAULT; + copied += copy; + ret = check_zeroed_user(v.iov_base + copy, + v.iov_len - copy); + if (ret <= 0) + return ret ?: -E2BIG; + 0;}), ({ + char *addr = kmap_atomic(v.bv_page); + copy = min_t(size_t, ksize - copied, v.bv_len); + memcpy(dst + copied, addr + v.bv_offset, copy); + copied += copy; + ret = memchr_inv(addr + v.bv_offset + copy, 0, + v.bv_len - copy) ? -E2BIG : 0; + kunmap_atomic(addr); + if (ret) + return ret; + }), ({ + copy = min(ksize - copied, v.iov_len); + memcpy(dst + copied, v.iov_base, copy); + if (memchr_inv(v.iov_base, 0, v.iov_len)) + return -E2BIG; + }) + ) + iov_iter_advance(i, usize); + } + return 0; +} +EXPORT_SYMBOL_GPL(copy_struct_from_iter); + static size_t pipe_zero(size_t bytes, struct iov_iter *i) { struct pipe_inode_info *pipe = i->pipe;