kprobes: Use helper to parse boolean input from userspace

The "enabled" file provides a debugfs interface to arm / disarm kprobes in the kernel. In order to parse the buffer containing the values written from userspace, the callback manually parses the user input to convert it to a boolean value. As taking a string value from userspace and converting it to boolean is a common operation, a helper kstrtobool_from_user() is already available in the kernel. Update the callback to use the common helper to parse the write buffer from userspace. Link: https://lkml.kernel.org/r/163163032637.489837.10678039554832855327.stgit@devnote2

Punit Agrawal committed 5 years ago

Commit 5d6de7d1 parent 8f7262c1 file · +6 −22Browse files

Showing the changes to kernel (1 of 1 file). Show all

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kernel/kprobes.c+6−22

@@ -2770,30 +2770,14 @@ static ssize_t read_enabled_file_bool(struct file *file, · 2769 unmodified lines
2770	2770	static ssize_t write_enabled_file_bool(struct file *file,
2771	2771	const char __user user_buf, size_t count, loff_t ppos)
2772	2772	{
2773		− char buf[32];
2774		− size_t buf_size;
2775		− int ret = 0;
2776		−
2777		− buf_size = min(count, (sizeof(buf)-1));
2778		− if (copy_from_user(buf, user_buf, buf_size))
2779		− return -EFAULT;
	2773	+ bool enable;
	2774	+ int ret;
2780	2775
2781		− buf[buf_size] = '\0';
2782		− switch (buf[0]) {
2783		− case 'y':
2784		− case 'Y':
2785		− case '1':
2786		− ret = arm_all_kprobes();
2787		− break;
2788		− case 'n':
2789		− case 'N':
2790		− case '0':
2791		− ret = disarm_all_kprobes();
2792		− break;
2793		− default:
2794		− return -EINVAL;
2795		− }
	2776	+ ret = kstrtobool_from_user(user_buf, count, &enable);
	2777	+ if (ret)
	2778	+ return ret;
2796	2779
	2780	+ ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
2797	2781	if (ret)
2798	2782	return ret;
2799	2783