From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: david@fromorbit.com
Cc: sandeen@redhat.com, linux-nfs@vger.kernel.org,
linux-cifs@vger.kernel.org, Amir Goldstein <amir73il@gmail.com>,
linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-mm@kvack.org, linux-btrfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
ocfs2-devel@oss.oracle.com
Subject: [PATCH v2 04/29] vfs: strengthen checking of file range inputs to generic_remap_checks
Date: Thu, 18 Oct 2018 11:56:07 -0700 [thread overview]
Message-ID: <20181018185607.GV28243@magnolia> (raw)
In-Reply-To: <153981628292.5568.2466587869276881561.stgit@magnolia>
From: Darrick J. Wong <darrick.wong@oracle.com>
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 <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
v2: restructurings as recommended by Al Viro
---
mm/filemap.c | 84 ++++++++++++++++++++++++++++++++++++----------------------
1 file changed, 52 insertions(+), 32 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 47e6bfd45a91..aab149fc1faa 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2915,6 +2915,42 @@ struct page *read_cache_page_gfp(struct address_space *mapping,
}
EXPORT_SYMBOL(read_cache_page_gfp);
+/*
+ * Don't operate on ranges the page cache doesn't support, and don't exceed the
+ * LFS limits. If pos is under the limit it becomes a short access. If it
+ * exceeds the limit we return -EFBIG.
+ */
+static int generic_access_check_limits(struct file *file, loff_t pos,
+ loff_t *count)
+{
+ struct inode *inode = file->f_mapping->host;
+ loff_t max_size = inode->i_sb->s_maxbytes;
+
+ if (!(file->f_flags & O_LARGEFILE))
+ max_size = MAX_NON_LFS;
+
+ if (unlikely(pos >= max_size))
+ return -EFBIG;
+ *count = min(*count, max_size - pos);
+ return 0;
+}
+
+static int generic_write_check_limits(struct file *file, loff_t pos,
+ loff_t *count)
+{
+ loff_t limit = rlimit(RLIMIT_FSIZE);
+
+ if (limit != RLIM_INFINITY) {
+ if (pos >= limit) {
+ send_sig(SIGXFSZ, current, 0);
+ return -EFBIG;
+ }
+ *count = min(*count, limit - pos);
+ }
+
+ return generic_access_check_limits(file, pos, count);
+}
+
/*
* Performs necessary checks before doing a write
*
@@ -2926,8 +2962,8 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
- unsigned long limit = rlimit(RLIMIT_FSIZE);
- loff_t pos;
+ loff_t count;
+ int ret;
if (!iov_iter_count(from))
return 0;
@@ -2936,40 +2972,15 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
if (iocb->ki_flags & IOCB_APPEND)
iocb->ki_pos = i_size_read(inode);
- pos = iocb->ki_pos;
-
if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
return -EINVAL;
- if (limit != RLIM_INFINITY) {
- if (iocb->ki_pos >= limit) {
- send_sig(SIGXFSZ, current, 0);
- return -EFBIG;
- }
- iov_iter_truncate(from, limit - (unsigned long)pos);
- }
-
- /*
- * LFS rule
- */
- if (unlikely(pos + iov_iter_count(from) > MAX_NON_LFS &&
- !(file->f_flags & O_LARGEFILE))) {
- if (pos >= MAX_NON_LFS)
- return -EFBIG;
- iov_iter_truncate(from, MAX_NON_LFS - (unsigned long)pos);
- }
-
- /*
- * Are we about to exceed the fs block limit ?
- *
- * If we have written data it becomes a short write. If we have
- * exceeded without writing data we send a signal and return EFBIG.
- * Linus frestrict idea will clean these up nicely..
- */
- if (unlikely(pos >= inode->i_sb->s_maxbytes))
- return -EFBIG;
+ count = iov_iter_count(from);
+ ret = generic_write_check_limits(file, iocb->ki_pos, &count);
+ if (ret)
+ return ret;
- iov_iter_truncate(from, inode->i_sb->s_maxbytes - pos);
+ iov_iter_truncate(from, count);
return iov_iter_count(from);
}
EXPORT_SYMBOL(generic_write_checks);
@@ -2991,6 +3002,7 @@ 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))
@@ -3014,6 +3026,14 @@ int generic_remap_checks(struct file *file_in, loff_t pos_in,
return -EINVAL;
count = min(count, size_in - (uint64_t)pos_in);
+ ret = generic_access_check_limits(file_in, pos_in, &count);
+ if (ret)
+ return ret;
+
+ ret = generic_write_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.
next prev parent reply other threads:[~2018-10-18 18:56 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-17 22:44 [PATCH v6 00/29] fs: fixes for serious clone/dedupe problems Darrick J. Wong
2018-10-17 22:44 ` [PATCH 01/29] vfs: vfs_clone_file_prep_inodes should return EINVAL for a clone from beyond EOF Darrick J. Wong
2018-10-17 22:44 ` [PATCH 02/29] vfs: check file ranges before cloning files Darrick J. Wong
2018-10-17 22:44 ` [PATCH 03/29] vfs: exit early from zero length remap operations Darrick J. Wong
2018-10-17 22:44 ` [PATCH 04/29] vfs: strengthen checking of file range inputs to generic_remap_checks Darrick J. Wong
2018-10-18 0:41 ` Al Viro
2018-10-18 4:37 ` Darrick J. Wong
2018-10-18 18:56 ` Darrick J. Wong [this message]
2018-10-17 22:44 ` [PATCH 05/29] vfs: avoid problematic remapping requests into partial EOF block Darrick J. Wong
2018-10-17 22:44 ` [PATCH 06/29] vfs: skip zero-length dedupe requests Darrick J. Wong
2018-10-17 22:45 ` [PATCH 07/29] vfs: rename vfs_clone_file_prep to be more descriptive Darrick J. Wong
2018-10-17 22:45 ` [PATCH 08/29] vfs: rename clone_verify_area to remap_verify_area Darrick J. Wong
2018-10-17 22:45 ` [PATCH 09/29] vfs: combine the clone and dedupe into a single remap_file_range Darrick J. Wong
2018-10-18 0:48 ` Al Viro
2018-10-18 4:47 ` Darrick J. Wong
2018-10-18 4:54 ` Al Viro
2018-10-18 5:03 ` Darrick J. Wong
2018-10-18 18:57 ` [PATCH v2 " Darrick J. Wong
2018-10-17 22:45 ` [PATCH 10/29] vfs: pass remap flags to generic_remap_file_range_prep Darrick J. Wong
2018-10-17 22:45 ` [PATCH 11/29] vfs: pass remap flags to generic_remap_checks Darrick J. Wong
2018-10-17 22:45 ` [PATCH 12/29] vfs: remap helper should update destination inode metadata Darrick J. Wong
2018-10-17 22:45 ` [PATCH 13/29] vfs: make remap_file_range functions take and return bytes completed Darrick J. Wong
2018-10-18 18:57 ` [PATCH v2 " Darrick J. Wong
2018-10-17 22:45 ` [PATCH 14/29] vfs: plumb remap flags through the vfs clone functions Darrick J. Wong
2018-10-17 22:46 ` [PATCH 15/29] vfs: plumb remap flags through the vfs dedupe functions Darrick J. Wong
2018-10-17 22:46 ` [PATCH 16/29] vfs: enable remap callers that can handle short operations Darrick J. Wong
2018-10-18 18:58 ` [PATCH v2 " Darrick J. Wong
2018-10-17 22:46 ` [PATCH 17/29] vfs: hide file range comparison function Darrick J. Wong
2018-10-17 22:46 ` [PATCH 18/29] vfs: clean up generic_remap_file_range_prep return value Darrick J. Wong
2018-10-17 22:46 ` [PATCH 19/29] ocfs2: truncate page cache for clone destination file before remapping Darrick J. Wong
2018-10-17 22:46 ` [PATCH 20/29] ocfs2: fix pagecache truncation prior to reflink Darrick J. Wong
2018-10-17 22:46 ` [PATCH 21/29] ocfs2: support partial clone range and dedupe range Darrick J. Wong
2018-10-17 22:46 ` [PATCH 22/29] ocfs2: remove ocfs2_reflink_remap_range Darrick J. Wong
2018-10-17 22:46 ` [PATCH 23/29] xfs: add a per-xfs trace_printk macro Darrick J. Wong
2018-10-17 22:47 ` [PATCH 24/29] xfs: fix pagecache truncation prior to reflink Darrick J. Wong
2018-10-17 22:47 ` [PATCH 25/29] xfs: clean up xfs_reflink_remap_blocks call site Darrick J. Wong
2018-10-17 22:47 ` [PATCH 26/29] xfs: support returning partial reflink results Darrick J. Wong
2018-10-17 22:47 ` [PATCH 27/29] xfs: remove redundant remap partial EOF block checks Darrick J. Wong
2018-10-17 22:47 ` [PATCH 28/29] xfs: remove xfs_reflink_remap_range Darrick J. Wong
2018-10-17 22:47 ` [PATCH 29/29] xfs: remove [cm]time update from reflink calls Darrick J. Wong
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