kernel/sysctl-test.c

Source file repositories/reference/linux-study-clean/kernel/sysctl-test.c

File Facts

System
Linux kernel
Corpus path
kernel/sysctl-test.c
Extension
.c
Size
10995 bytes
Lines
393
Domain
Core OS
Bucket
Scheduler, Processes, Timers, Sync, And Syscalls
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * KUnit test of proc sysctl.
 */

#include <kunit/test.h>
#include <linux/sysctl.h>

#define KUNIT_PROC_READ 0
#define KUNIT_PROC_WRITE 1

/*
 * Test that proc_dointvec will not try to use a NULL .data field even when the
 * length is non-zero.
 */
static void sysctl_test_api_dointvec_null_tbl_data(struct kunit *test)
{
	struct ctl_table null_data_table = {
		.procname = "foo",
		/*
		 * Here we are testing that proc_dointvec behaves correctly when
		 * we give it a NULL .data field. Normally this would point to a
		 * piece of memory where the value would be stored.
		 */
		.data		= NULL,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
		.extra1		= SYSCTL_ZERO,
		.extra2         = SYSCTL_ONE_HUNDRED,
	};
	/*
	 * proc_dointvec expects a buffer in user space, so we allocate one. We
	 * also need to cast it to __user so sparse doesn't get mad.
	 */
	void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
							   GFP_USER);
	size_t len;
	loff_t pos;

	/*
	 * We don't care what the starting length is since proc_dointvec should
	 * not try to read because .data is NULL.
	 */
	len = 1234;
	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&null_data_table,
					       KUNIT_PROC_READ, buffer, &len,
					       &pos));
	KUNIT_EXPECT_EQ(test, 0, len);

	/*
	 * See above.
	 */
	len = 1234;
	KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&null_data_table,
					       KUNIT_PROC_WRITE, buffer, &len,
					       &pos));
	KUNIT_EXPECT_EQ(test, 0, len);
}

/*
 * Similar to the previous test, we create a struct ctrl_table that has a .data
 * field that proc_dointvec cannot do anything with; however, this time it is
 * because we tell proc_dointvec that the size is 0.
 */
static void sysctl_test_api_dointvec_table_maxlen_unset(struct kunit *test)
{
	int data = 0;
	struct ctl_table data_maxlen_unset_table = {
		.procname = "foo",
		.data		= &data,
		/*
		 * So .data is no longer NULL, but we tell proc_dointvec its
		 * length is 0, so it still shouldn't try to use it.
		 */
		.maxlen		= 0,
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
		.extra1		= SYSCTL_ZERO,
		.extra2         = SYSCTL_ONE_HUNDRED,
	};
	void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
							   GFP_USER);
	size_t len;
	loff_t pos;

	/*
	 * As before, we don't care what buffer length is because proc_dointvec
	 * cannot do anything because its internal .data buffer has zero length.
	 */

Annotation

Implementation Notes