linux-kernel - [PATCH 4/4] debugfs: Add read-only/write-only bool file ops

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Message-Id: <1444698552-12369-5-git-send-email-sboyd@codeaurora.org>
Date:	Mon, 12 Oct 2015 18:09:12 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH 4/4] debugfs: Add read-only/write-only bool file ops

There aren't any read-only or write-only bool file ops, but there
is a caller of debugfs_create_bool() that calls it with mode
equal to 0400. This leads to the possibility of userspace
modifying the file, so let's use the newly created
debugfs_create_mode() helper here to fix this.

Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---
 fs/debugfs/file.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index e8e73aebe6b8..8450549d54a9 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -450,6 +450,18 @@ static const struct file_operations fops_bool = {
 	.llseek =	default_llseek,
 };
 
+static const struct file_operations fops_bool_ro = {
+	.read =		debugfs_read_file_bool,
+	.open =		simple_open,
+	.llseek =	default_llseek,
+};
+
+static const struct file_operations fops_bool_wo = {
+	.write =	debugfs_write_file_bool,
+	.open =		simple_open,
+	.llseek =	default_llseek,
+};
+
 /**
  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
  * @name: a pointer to a string containing the name of the file to create.
@@ -477,7 +489,8 @@ static const struct file_operations fops_bool = {
 struct dentry *debugfs_create_bool(const char *name, umode_t mode,
 				   struct dentry *parent, bool *value)
 {
-	return debugfs_create_file(name, mode, parent, value, &fops_bool);
+	return debugfs_create_mode(name, mode, parent, value, &fops_bool,
+				   &fops_bool_ro, &fops_bool_wo);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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