From patchwork Fri Jul 24 18:44:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Satya Tangirala X-Patchwork-Id: 11684139 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 04F7B1392 for ; Fri, 24 Jul 2020 18:45:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAE58206F0 for ; Fri, 24 Jul 2020 18:45:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fiwV9W1r" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726728AbgGXSpL (ORCPT ); Fri, 24 Jul 2020 14:45:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726493AbgGXSpI (ORCPT ); Fri, 24 Jul 2020 14:45:08 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B30CC0619D3 for ; Fri, 24 Jul 2020 11:45:08 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id u189so11464366ybg.17 for ; Fri, 24 Jul 2020 11:45:08 -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=e3QQnyJEAo5uWrYUDsDCPQeAxWHqtOZ6h6W8L9vv5Ok=; b=fiwV9W1rn8xIx3eZin4HllP1i3QSz+XUBPdewpcOoRimkQuoOrFrKuu38oLKdxH/DL vjPZdSY437ObQqT07i4flLI+1fCaVT7Ymuca2SmUy4H+CrkIrxGI6jsA4EgPZZauHHUt w/Tg2NAvoP98hkyUVK+5yBTBUA/3l8/6rYlDlWHfAmPIHHvKIXtSVukfxFwkMujd4Zv2 aD16Gnr0+DPz3kaVcz9meN+oEqmVMDwbCt7HOOFTt1XvP0x1pFx5ASr/LQ43SiIqmiEF dJNIHgPR6/zhiU7zn6P9EKElVptiQsjVOLZRH9RuAggnZ6iX8hjjZSEwMbuHQegF+4MK IBnw== 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=e3QQnyJEAo5uWrYUDsDCPQeAxWHqtOZ6h6W8L9vv5Ok=; b=azpZFMhC0e3TPcGkJOvkA7ZgeL3tuGJHoRYlf/9NwWNvqkC5rAAN4vIa4ZWckr5ARc JXG0IRsx2pJa1GP0kWHfnVprIO0GQOqXbp3LIQpSRSKYeHdOuDvtc9qGjkzKagtf4c7J NgE2Gg0Qkz8JknnrUFTuIm8gzdOx/jndXNJKeI5YyxBlzZdjmDU1lY+uNlKo5xMb17fU ZLsRKfJoxRe5hiikGxe0/t52+s+wYxagTg29mVEROLPBUT2ICidKIR9GB1OICkTWLddN OmoybXKoS5P6H/+ds38p6X9wFEg6QdahOvJswJsieJQpt2g9e6uUl3Rle5ALrRPj8EUY 5HJA== X-Gm-Message-State: AOAM530WmRsyLGLtaiFBAaxqd5gyEAmDsPc5Xp7lAwD7sUkhL/qCopgM 75rbs5q1JWYqAVv358UEeoAipMmrdw4= X-Google-Smtp-Source: ABdhPJwl1gKyF3pfJ5ie868kPXKBua9doUzwDRqGLr8lKTqxr1HHAMw3xL4wn/F/CGySesYoXqUp4cD0u0I= X-Received: by 2002:a25:2417:: with SMTP id k23mr15167611ybk.300.1595616307826; Fri, 24 Jul 2020 11:45:07 -0700 (PDT) Date: Fri, 24 Jul 2020 18:44:55 +0000 In-Reply-To: <20200724184501.1651378-1-satyat@google.com> Message-Id: <20200724184501.1651378-2-satyat@google.com> Mime-Version: 1.0 References: <20200724184501.1651378-1-satyat@google.com> X-Mailer: git-send-email 2.28.0.rc0.142.g3c755180ce-goog Subject: [PATCH v6 1/7] fscrypt: Add functions for direct I/O support From: Satya Tangirala To: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org Cc: linux-xfs@vger.kernel.org, Eric Biggers , Satya Tangirala Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Eric Biggers Introduce fscrypt_dio_supported() to check whether a direct I/O request is unsupported due to encryption constraints. Also introduce fscrypt_limit_io_blocks() to limit how many blocks can be added to a bio being prepared for direct I/O. This is needed for filesystems that use the iomap direct I/O implementation to avoid DUN wraparound in the middle of a bio (which is possible with the IV_INO_LBLK_32 IV generation method). Elsewhere fscrypt_mergeable_bio() is used for this, but iomap operates on logical ranges directly, so filesystems using iomap won't have a chance to call fscrypt_mergeable_bio() on every block added to a bio. So we need this function which limits a logical range in one go. Signed-off-by: Eric Biggers Co-developed-by: Satya Tangirala Signed-off-by: Satya Tangirala --- fs/crypto/crypto.c | 8 +++++ fs/crypto/inline_crypt.c | 74 ++++++++++++++++++++++++++++++++++++++++ include/linux/fscrypt.h | 18 ++++++++++ 3 files changed, 100 insertions(+) diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 9212325763b0..f72f22a718b2 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -69,6 +69,14 @@ void fscrypt_free_bounce_page(struct page *bounce_page) } EXPORT_SYMBOL(fscrypt_free_bounce_page); +/* + * Generate the IV for the given logical block number within the given file. + * For filenames encryption, lblk_num == 0. + * + * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks() + * needs to know about any IV generation methods where the low bits of IV don't + * simply contain the lblk_num (e.g., IV_INO_LBLK_32). + */ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci) { diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c index d7aecadf33c1..4cdf807b89b9 100644 --- a/fs/crypto/inline_crypt.c +++ b/fs/crypto/inline_crypt.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "fscrypt_private.h" @@ -362,3 +363,76 @@ bool fscrypt_mergeable_bio_bh(struct bio *bio, return fscrypt_mergeable_bio(bio, inode, next_lblk); } EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh); + +/** + * fscrypt_dio_supported() - check whether a direct I/O request is unsupported + * due to encryption constraints + * @iocb: the file and position the I/O is targeting + * @iter: the I/O data segment(s) + * + * Return: true if direct I/O is supported + */ +bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter) +{ + const struct inode *inode = file_inode(iocb->ki_filp); + const unsigned int blocksize = i_blocksize(inode); + + /* If the file is unencrypted, no veto from us. */ + if (!fscrypt_needs_contents_encryption(inode)) + return true; + + /* We only support direct I/O with inline crypto, not fs-layer crypto */ + if (!fscrypt_inode_uses_inline_crypto(inode)) + return false; + + /* + * Since the granularity of encryption is filesystem blocks, the I/O + * must be block aligned -- not just disk sector aligned. + */ + if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize)) + return false; + + return true; +} +EXPORT_SYMBOL_GPL(fscrypt_dio_supported); + +/** + * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs + * @inode: the file on which I/O is being done + * @lblk: the block at which the I/O is being started from + * @nr_blocks: the number of blocks we want to submit starting at @pos + * + * Determine the limit to the number of blocks that can be submitted in the bio + * targeting @pos without causing a data unit number (DUN) discontinuity. + * + * This is normally just @nr_blocks, as normally the DUNs just increment along + * with the logical blocks. (Or the file is not encrypted.) + * + * In rare cases, fscrypt can be using an IV generation method that allows the + * DUN to wrap around within logically continuous blocks, and that wraparound + * will occur. If this happens, a value less than @nr_blocks will be returned + * so that the wraparound doesn't occur in the middle of the bio. + * + * Return: the actual number of blocks that can be submitted + */ +u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks) +{ + const struct fscrypt_info *ci = inode->i_crypt_info; + u32 dun; + + if (!fscrypt_inode_uses_inline_crypto(inode)) + return nr_blocks; + + if (nr_blocks <= 1) + return nr_blocks; + + if (!(fscrypt_policy_flags(&ci->ci_policy) & + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) + return nr_blocks; + + /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ + + dun = ci->ci_hashed_ino + lblk; + + return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); +} diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index bb257411365f..5de122ec0464 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -559,6 +559,10 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, bool fscrypt_mergeable_bio_bh(struct bio *bio, const struct buffer_head *next_bh); +bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter); + +u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks); + #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) @@ -587,6 +591,20 @@ static inline bool fscrypt_mergeable_bio_bh(struct bio *bio, { return true; } + +static inline bool fscrypt_dio_supported(struct kiocb *iocb, + struct iov_iter *iter) +{ + const struct inode *inode = file_inode(iocb->ki_filp); + + return !fscrypt_needs_contents_encryption(inode); +} + +static inline u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, + u64 nr_blocks) +{ + return nr_blocks; +} #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ /**