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From: Christoph Hellwig <hch@lst.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
	linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 07/13] sysfs: add ->seq_show support to sysfs_ops
Date: Mon, 13 Sep 2021 07:41:15 +0200	[thread overview]
Message-ID: <20210913054121.616001-8-hch@lst.de> (raw)
In-Reply-To: <20210913054121.616001-1-hch@lst.de>

Allow attributes to directly use the seq_file method instead of
carving out a buffer that can easily lead to buffer overflows.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/sysfs/file.c       | 19 ++++++++++++++-----
 include/linux/sysfs.h |  9 +++++++--
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 42dcf96881b68..12e0bfe40a2b4 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -45,6 +45,9 @@ static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
 	ssize_t count;
 	char *buf;
 
+	if (ops->seq_show)
+		return ops->seq_show(kobj, of->kn->priv, sf);
+
 	if (WARN_ON_ONCE(!ops->show))
 		return -EINVAL;
 
@@ -268,6 +271,10 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
 		return -EINVAL;
 
 	if (mode & SYSFS_PREALLOC) {
+		if (WARN(sysfs_ops->seq_show, KERN_ERR
+				"seq_show not supported on prealloc file: %s\n",
+				kobject_name(kobj)))
+			return -EINVAL;
 		if (sysfs_ops->show && sysfs_ops->store)
 			ops = &sysfs_prealloc_kfops_rw;
 		else if (sysfs_ops->show)
@@ -275,12 +282,14 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
 		else if (sysfs_ops->store)
 			ops = &sysfs_prealloc_kfops_wo;
 	} else {
-		if (sysfs_ops->show && sysfs_ops->store)
-			ops = &sysfs_file_kfops_rw;
-		else if (sysfs_ops->show)
-			ops = &sysfs_file_kfops_ro;
-		else if (sysfs_ops->store)
+		if (sysfs_ops->seq_show || sysfs_ops->show) {
+			if (sysfs_ops->store)
+				ops = &sysfs_file_kfops_rw;
+			else
+				ops = &sysfs_file_kfops_ro;
+		} else if (sysfs_ops->store) {
 			ops = &sysfs_file_kfops_wo;
+		}
 	}
 
 	if (!ops)
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index e3f1e8ac1f85b..e1ab4da716730 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -236,8 +236,13 @@ struct bin_attribute bin_attr_##_name = __BIN_ATTR_WO(_name, _size)
 struct bin_attribute bin_attr_##_name = __BIN_ATTR_RW(_name, _size)
 
 struct sysfs_ops {
-	ssize_t	(*show)(struct kobject *, struct attribute *, char *);
-	ssize_t	(*store)(struct kobject *, struct attribute *, const char *, size_t);
+	int	(*seq_show)(struct kobject *kobj, struct attribute *attr,
+			struct seq_file *sf);
+	ssize_t	(*store)(struct kobject *kobj, struct attribute *attr,
+			const char *buf, size_t size);
+
+	/* deprecated except for preallocated attributes: */
+	ssize_t	(*show)(struct kobject *kob, struct attribute *attr, char *buf);
 };
 
 #ifdef CONFIG_SYSFS
-- 
2.30.2


  parent reply	other threads:[~2021-09-13  5:49 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13  5:41 start switching sysfs attributes to expose the seq_file Christoph Hellwig
2021-09-13  5:41 ` [PATCH 01/13] seq_file: mark seq_get_buf as deprecated Christoph Hellwig
2021-09-13 13:19   ` Christian Brauner
2021-09-13 16:22   ` Daniel Wagner
2021-09-13 16:29   ` Tejun Heo
2021-09-13  5:41 ` [PATCH 02/13] kernfs: remove kernfs_create_file and kernfs_create_file_ns Christoph Hellwig
2021-09-13 13:20   ` Christian Brauner
2021-09-13  5:41 ` [PATCH 03/13] kernfs: remove the unused lockdep_key field in struct kernfs_ops Christoph Hellwig
2021-09-13 13:21   ` Christian Brauner
2021-09-13 16:30   ` Tejun Heo
2021-09-13  5:41 ` [PATCH 04/13] sysfs: split out binary attribute handling from sysfs_add_file_mode_ns Christoph Hellwig
2021-09-13 13:26   ` Christian Brauner
2021-09-13  5:41 ` [PATCH 05/13] sysfs: refactor sysfs_add_file_mode_ns Christoph Hellwig
2021-09-13 13:27   ` Christian Brauner
2021-09-13  5:41 ` [PATCH 06/13] sysfs: simplify sysfs_kf_seq_show Christoph Hellwig
2021-09-13  5:41 ` Christoph Hellwig [this message]
2021-09-13 13:30   ` [PATCH 07/13] sysfs: add ->seq_show support to sysfs_ops Christian Brauner
2021-09-13  5:41 ` [PATCH 08/13] block: convert the blk_mq_hw_ctx attrs to use ->seq_show Christoph Hellwig
2021-09-13  5:41 ` [PATCH 09/13] block: convert the blk_integrity " Christoph Hellwig
2021-09-13  5:41 ` [PATCH 10/13] block: convert the request_queue " Christoph Hellwig
2021-09-13  5:41 ` [PATCH 11/13] block: convert the elevator_queue " Christoph Hellwig
2021-09-13  5:41 ` [PATCH 12/13] xfs: convert xfs_errortag " Christoph Hellwig
2021-09-13  5:41 ` [PATCH 13/13] xfs: convert xfs_sysfs " Christoph Hellwig
2021-09-13  6:27   ` Greg Kroah-Hartman
2021-09-14  1:20     ` Dave Chinner
2021-09-14  5:12       ` Greg Kroah-Hartman
2021-09-14 10:56         ` Dave Chinner
2021-09-14  7:30     ` Christoph Hellwig
2021-09-14 15:28       ` Greg Kroah-Hartman
2021-09-14 15:30         ` Christoph Hellwig
2021-09-14 15:41           ` Greg Kroah-Hartman
2021-09-15  7:04             ` Christoph Hellwig
2021-09-15  7:07               ` Greg Kroah-Hartman
2021-09-13 16:39 ` start switching sysfs attributes to expose the seq_file Bart Van Assche
2021-09-13 16:46   ` Greg Kroah-Hartman
2021-09-14  2:53     ` Bart Van Assche
2021-09-13 16:46 ` Tejun Heo

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