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From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>, David Howells <dhowells@redhat.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	netfilter-devel@vger.kernel.org
Subject: [PATCH 10/14] fs: add a __kernel_read helper
Date: Wed, 13 May 2020 08:56:52 +0200
Message-ID: <20200513065656.2110441-11-hch@lst.de> (raw)
In-Reply-To: <20200513065656.2110441-1-hch@lst.de>

This is the counterpart to __kernel_write, and skip the rw_verify_area
call compared to kernel_read.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/read_write.c    | 21 +++++++++++++++++++++
 include/linux/fs.h |  1 +
 2 files changed, 22 insertions(+)

diff --git a/fs/read_write.c b/fs/read_write.c
index 8cfca5f8fc3ce..bd12af8a895c8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -430,6 +430,27 @@ ssize_t __vfs_read(struct file *file, char __user *buf, size_t count,
 		return -EINVAL;
 }
 
+ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
+{
+	mm_segment_t old_fs = get_fs();
+	ssize_t ret;
+
+	if (!(file->f_mode & FMODE_CAN_READ))
+		return -EINVAL;
+
+	if (count > MAX_RW_COUNT)
+		count =  MAX_RW_COUNT;
+	set_fs(KERNEL_DS);
+	ret = __vfs_read(file, (void __user *)buf, count, pos);
+	set_fs(old_fs);
+	if (ret > 0) {
+		fsnotify_access(file);
+		add_rchar(current, ret);
+	}
+	inc_syscr(current);
+	return ret;
+}
+
 ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 {
 	mm_segment_t old_fs;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 21f126957c2cf..6441aaa25f8f2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3011,6 +3011,7 @@ extern int kernel_read_file_from_path_initns(const char *, void **, loff_t *, lo
 extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
 				    enum kernel_read_file_id);
 extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
+ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos);
 extern ssize_t kernel_write(struct file *, const void *, size_t, loff_t *);
 extern ssize_t __kernel_write(struct file *, const void *, size_t, loff_t *);
 extern struct file * open_exec(const char *);
-- 
2.26.2


  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-13  6:56 clean up kernel_{read,write} & friends v2 Christoph Hellwig
2020-05-13  6:56 ` [PATCH 01/14] cachefiles: switch to kernel_write Christoph Hellwig
2020-05-13  6:56 ` [PATCH 02/14] autofs: " Christoph Hellwig
2020-05-14  8:25   ` Ian Kent
2020-05-13  6:56 ` [PATCH 03/14] bpfilter: " Christoph Hellwig
2020-05-13  6:56 ` [PATCH 04/14] fs: unexport __kernel_write Christoph Hellwig
2020-05-13  6:56 ` [PATCH 05/14] fs: check FMODE_WRITE in __kernel_write Christoph Hellwig
2020-05-13  6:56 ` [PATCH 06/14] fs: remove the call_{read,write}_iter functions Christoph Hellwig
2020-05-13  6:56 ` [PATCH 07/14] fs: implement kernel_write using __kernel_write Christoph Hellwig
2020-05-13  6:56 ` [PATCH 08/14] fs: remove __vfs_write Christoph Hellwig
2020-05-13  6:56 ` [PATCH 09/14] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-05-13  6:56 ` Christoph Hellwig [this message]
2020-05-13  6:56 ` [PATCH 11/14] integrity/ima: switch to using __kernel_read Christoph Hellwig
2020-05-13  6:56 ` [PATCH 12/14] fs: implement kernel_read " Christoph Hellwig
2020-05-13  6:56 ` [PATCH 13/14] fs: remove __vfs_read Christoph Hellwig
2020-05-13  6:56 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig
2020-05-15 15:21 ` [PATCH 01/14] cachefiles: switch to kernel_write David Howells
     [not found] ` <20200516030436.19448-1-hdanton@sina.com>
2020-05-18  6:42   ` [PATCH 09/14] fs: don't change the address limit for ->write_iter in __kernel_write Christoph Hellwig
2020-05-20 15:59 ` clean up kernel_{read,write} & friends v2 Christoph Hellwig
2020-05-28  5:40 Christoph Hellwig
2020-05-28  5:40 ` [PATCH 10/14] fs: add a __kernel_read helper Christoph Hellwig

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