From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 029696B026D for ; Tue, 9 Oct 2018 20:11:26 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id 8-v6so3237783pfr.0 for ; Tue, 09 Oct 2018 17:11:25 -0700 (PDT) Received: from aserp2120.oracle.com (aserp2120.oracle.com. [141.146.126.78]) by mx.google.com with ESMTPS id f9-v6si25660578plm.126.2018.10.09.17.11.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Oct 2018 17:11:24 -0700 (PDT) Subject: [PATCH 06/25] vfs: strengthen checking of file range inputs to generic_remap_checks From: "Darrick J. Wong" Date: Tue, 09 Oct 2018 17:11:20 -0700 Message-ID: <153913028015.32295.15993665528948323051.stgit@magnolia> In-Reply-To: <153913023835.32295.13962696655740190941.stgit@magnolia> References: <153913023835.32295.13962696655740190941.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: david@fromorbit.com, darrick.wong@oracle.com Cc: sandeen@redhat.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com From: Darrick J. Wong File range remapping, if allowed to run past the destination file's EOF, is an optimization on a regular file write. Regular file writes that extend the file length are subject to various constraints which are not checked by range cloning. This is a correctness problem because we're never allowed to touch ranges that the page cache can't support (s_maxbytes); we're not supposed to deal with large offsets (MAX_NON_LFS) if O_LARGEFILE isn't set; and we must obey resource limits (RLIMIT_FSIZE). Therefore, add these checks to the new generic_remap_checks function so that we curtail unexpected behavior. Signed-off-by: Darrick J. Wong --- mm/filemap.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index 14041a8468ba..59056bd9c58a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2974,6 +2974,27 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) } EXPORT_SYMBOL(generic_write_checks); +static int +generic_remap_check_limits(struct file *file, loff_t pos, uint64_t *count) +{ + struct inode *inode = file->f_mapping->host; + + /* Don't exceed the LFS limits. */ + if (unlikely(pos + *count > MAX_NON_LFS && + !(file->f_flags & O_LARGEFILE))) { + if (pos >= MAX_NON_LFS) + return -EFBIG; + *count = min(*count, MAX_NON_LFS - (uint64_t)pos); + } + + /* Don't operate on ranges the page cache doesn't support. */ + if (unlikely(pos >= inode->i_sb->s_maxbytes)) + return -EFBIG; + + *count = min(*count, inode->i_sb->s_maxbytes - (uint64_t)pos); + return 0; +} + /* * Performs necessary checks before doing a clone. * @@ -2992,6 +3013,7 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, uint64_t bcount; loff_t size_in, size_out; loff_t bs = inode_out->i_sb->s_blocksize; + int ret; /* The start of both ranges must be aligned to an fs block. */ if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs)) @@ -3015,6 +3037,23 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in, return -EINVAL; count = min(count, size_in - (uint64_t)pos_in); + /* Don't exceed RLMIT_FSIZE in the file we're writing into. */ + if (limit != RLIM_INFINITY) { + if (pos_out >= limit) { + send_sig(SIGXFSZ, current, 0); + return -EFBIG; + } + count = min(count, limit - (uint64_t)pos_out); + } + + ret = generic_remap_check_limits(file_in, pos_in, &count); + if (ret) + return ret; + + ret = generic_remap_check_limits(file_out, pos_out, &count); + if (ret) + return ret; + /* * If the user wanted us to link to the infile's EOF, round up to the * next block boundary for this check.