Linux-Security-Module Archive on lore.kernel.org
 help / color / Atom feed
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 14/14] fs: don't change the address limit for ->read_iter in __kernel_read
Date: Wed, 13 May 2020 08:56:56 +0200
Message-ID: <20200513065656.2110441-15-hch@lst.de> (raw)
In-Reply-To: <20200513065656.2110441-1-hch@lst.de>

If we read to a file that implements ->read_iter there is no need
to change the address limit if we send a kvec down.  Implement that
case, and prefer it over using plain ->read with a changed address
limit if available.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/read_write.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 46ddfce17e839..c93acbd8bf5a3 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -421,7 +421,6 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo
 
 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))
@@ -429,14 +428,25 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 
 	if (count > MAX_RW_COUNT)
 		count =  MAX_RW_COUNT;
-	set_fs(KERNEL_DS);
-	if (file->f_op->read)
+	if (file->f_op->read_iter) {
+		struct kvec iov = { .iov_base = buf, .iov_len = count };
+		struct kiocb kiocb;
+		struct iov_iter iter;
+
+		init_sync_kiocb(&kiocb, file);
+		kiocb.ki_pos = *pos;
+		iov_iter_kvec(&iter, READ, &iov, 1, count);
+		ret = file->f_op->read_iter(&kiocb, &iter);
+		*pos = kiocb.ki_pos;
+	} else if (file->f_op->read) {
+		mm_segment_t old_fs = get_fs();
+
+		set_fs(KERNEL_DS);
 		ret = file->f_op->read(file, (void __user *)buf, count, pos);
-	else if (file->f_op->read_iter)
-		ret = new_sync_read(file, (void __user *)buf, count, pos);
-	else
+		set_fs(old_fs);
+	} else {
 		ret = -EINVAL;
-	set_fs(old_fs);
+	}
 	if (ret > 0) {
 		fsnotify_access(file);
 		add_rchar(current, ret);
-- 
2.26.2


  parent reply index

Thread overview: 22+ 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 ` [PATCH 10/14] fs: add a __kernel_read helper Christoph Hellwig
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 ` Christoph Hellwig [this message]
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 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig
2020-05-28 19:03   ` Al Viro
2020-06-24 16:13 clean up kernel_{read,write} & friends v5 Christoph Hellwig
2020-06-24 16:13 ` [PATCH 14/14] fs: don't change the address limit for ->read_iter in __kernel_read Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200513065656.2110441-15-hch@lst.de \
    --to=hch@lst.de \
    --cc=dhowells@redhat.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=netfilter-devel@vger.kernel.org \
    --cc=raven@themaw.net \
    --cc=viro@zeniv.linux.org.uk \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Security-Module Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-security-module/0 linux-security-module/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-security-module linux-security-module/ https://lore.kernel.org/linux-security-module \
		linux-security-module@vger.kernel.org
	public-inbox-index linux-security-module

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-security-module


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git