kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()

[ Upstream commit 2cb80dbbbaba4f2f86f686c34cb79ea5cbfb0edb ]

KUnit tests for initialized data behavior of proc_dointvec that is
explicitly checked in the code. Includes basic parsing tests including
int min/max overflow.

Signed-off-by: Iurii Zaikin <yzaikin@google.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Iurii Zaikin 2019-09-23 02:02:47 -07:00 committed by Greg Kroah-Hartman
parent 5d087e3578
commit 03c4d42e3c
3 changed files with 405 additions and 0 deletions

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@ -115,6 +115,8 @@ obj-$(CONFIG_TORTURE_TEST) += torture.o
obj-$(CONFIG_HAS_IOMEM) += iomem.o
obj-$(CONFIG_RSEQ) += rseq.o
obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
KASAN_SANITIZE_stackleak.o := n
KCOV_INSTRUMENT_stackleak.o := n

392
kernel/sysctl-test.c Normal file
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@ -0,0 +1,392 @@
// 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
static int i_zero;
static int i_one_hundred = 100;
/*
* 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 = &i_zero,
.extra2 = &i_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, (size_t)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, (size_t)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 = &i_zero,
.extra2 = &i_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.
*/
len = 1234;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&data_maxlen_unset_table,
KUNIT_PROC_READ, buffer, &len,
&pos));
KUNIT_EXPECT_EQ(test, (size_t)0, len);
/*
* See previous comment.
*/
len = 1234;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&data_maxlen_unset_table,
KUNIT_PROC_WRITE, buffer, &len,
&pos));
KUNIT_EXPECT_EQ(test, (size_t)0, len);
}
/*
* Here we provide a valid struct ctl_table, but we try to read and write from
* it using a buffer of zero length, so it should still fail in a similar way as
* before.
*/
static void sysctl_test_api_dointvec_table_len_is_zero(struct kunit *test)
{
int data = 0;
/* Good table. */
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
GFP_USER);
/*
* However, now our read/write buffer has zero length.
*/
size_t len = 0;
loff_t pos;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ, buffer,
&len, &pos));
KUNIT_EXPECT_EQ(test, (size_t)0, len);
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE, buffer,
&len, &pos));
KUNIT_EXPECT_EQ(test, (size_t)0, len);
}
/*
* Test that proc_dointvec refuses to read when the file position is non-zero.
*/
static void sysctl_test_api_dointvec_table_read_but_position_set(
struct kunit *test)
{
int data = 0;
/* Good table. */
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
void __user *buffer = (void __user *)kunit_kzalloc(test, sizeof(int),
GFP_USER);
/*
* We don't care about our buffer length because we start off with a
* non-zero file position.
*/
size_t len = 1234;
/*
* proc_dointvec should refuse to read into the buffer since the file
* pos is non-zero.
*/
loff_t pos = 1;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ, buffer,
&len, &pos));
KUNIT_EXPECT_EQ(test, (size_t)0, len);
}
/*
* Test that we can read a two digit number in a sufficiently size buffer.
* Nothing fancy.
*/
static void sysctl_test_dointvec_read_happy_single_positive(struct kunit *test)
{
int data = 0;
/* Good table. */
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
size_t len = 4;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
/* Store 13 in the data field. */
*((int *)table.data) = 13;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ,
user_buffer, &len, &pos));
KUNIT_ASSERT_EQ(test, (size_t)3, len);
buffer[len] = '\0';
/* And we read 13 back out. */
KUNIT_EXPECT_STREQ(test, "13\n", buffer);
}
/*
* Same as previous test, just now with negative numbers.
*/
static void sysctl_test_dointvec_read_happy_single_negative(struct kunit *test)
{
int data = 0;
/* Good table. */
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
size_t len = 5;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
*((int *)table.data) = -16;
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_READ,
user_buffer, &len, &pos));
KUNIT_ASSERT_EQ(test, (size_t)4, len);
buffer[len] = '\0';
KUNIT_EXPECT_STREQ(test, "-16\n", (char *)buffer);
}
/*
* Test that a simple positive write works.
*/
static void sysctl_test_dointvec_write_happy_single_positive(struct kunit *test)
{
int data = 0;
/* Good table. */
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
char input[] = "9";
size_t len = sizeof(input) - 1;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
memcpy(buffer, input, len);
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE,
user_buffer, &len, &pos));
KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
KUNIT_EXPECT_EQ(test, sizeof(input) - 1, (size_t)pos);
KUNIT_EXPECT_EQ(test, 9, *((int *)table.data));
}
/*
* Same as previous test, but now with negative numbers.
*/
static void sysctl_test_dointvec_write_happy_single_negative(struct kunit *test)
{
int data = 0;
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
char input[] = "-9";
size_t len = sizeof(input) - 1;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
memcpy(buffer, input, len);
KUNIT_EXPECT_EQ(test, 0, proc_dointvec(&table, KUNIT_PROC_WRITE,
user_buffer, &len, &pos));
KUNIT_EXPECT_EQ(test, sizeof(input) - 1, len);
KUNIT_EXPECT_EQ(test, sizeof(input) - 1, (size_t)pos);
KUNIT_EXPECT_EQ(test, -9, *((int *)table.data));
}
/*
* Test that writing a value smaller than the minimum possible value is not
* allowed.
*/
static void sysctl_test_api_dointvec_write_single_less_int_min(
struct kunit *test)
{
int data = 0;
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
size_t max_len = 32, len = max_len;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, max_len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
unsigned long abs_of_less_than_min = (unsigned long)INT_MAX
- (INT_MAX + INT_MIN) + 1;
/*
* We use this rigmarole to create a string that contains a value one
* less than the minimum accepted value.
*/
KUNIT_ASSERT_LT(test,
(size_t)snprintf(buffer, max_len, "-%lu",
abs_of_less_than_min),
max_len);
KUNIT_EXPECT_EQ(test, -EINVAL, proc_dointvec(&table, KUNIT_PROC_WRITE,
user_buffer, &len, &pos));
KUNIT_EXPECT_EQ(test, max_len, len);
KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
}
/*
* Test that writing the maximum possible value works.
*/
static void sysctl_test_api_dointvec_write_single_greater_int_max(
struct kunit *test)
{
int data = 0;
struct ctl_table table = {
.procname = "foo",
.data = &data,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
.extra1 = &i_zero,
.extra2 = &i_one_hundred,
};
size_t max_len = 32, len = max_len;
loff_t pos = 0;
char *buffer = kunit_kzalloc(test, max_len, GFP_USER);
char __user *user_buffer = (char __user *)buffer;
unsigned long greater_than_max = (unsigned long)INT_MAX + 1;
KUNIT_ASSERT_GT(test, greater_than_max, (unsigned long)INT_MAX);
KUNIT_ASSERT_LT(test, (size_t)snprintf(buffer, max_len, "%lu",
greater_than_max),
max_len);
KUNIT_EXPECT_EQ(test, -EINVAL, proc_dointvec(&table, KUNIT_PROC_WRITE,
user_buffer, &len, &pos));
KUNIT_ASSERT_EQ(test, max_len, len);
KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
}
static struct kunit_case sysctl_test_cases[] = {
KUNIT_CASE(sysctl_test_api_dointvec_null_tbl_data),
KUNIT_CASE(sysctl_test_api_dointvec_table_maxlen_unset),
KUNIT_CASE(sysctl_test_api_dointvec_table_len_is_zero),
KUNIT_CASE(sysctl_test_api_dointvec_table_read_but_position_set),
KUNIT_CASE(sysctl_test_dointvec_read_happy_single_positive),
KUNIT_CASE(sysctl_test_dointvec_read_happy_single_negative),
KUNIT_CASE(sysctl_test_dointvec_write_happy_single_positive),
KUNIT_CASE(sysctl_test_dointvec_write_happy_single_negative),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_less_int_min),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_greater_int_max),
{}
};
static struct kunit_suite sysctl_test_suite = {
.name = "sysctl_test",
.test_cases = sysctl_test_cases,
};
kunit_test_suite(sysctl_test_suite);

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@ -1939,6 +1939,17 @@ config TEST_SYSCTL
If unsure, say N.
config SYSCTL_KUNIT_TEST
bool "KUnit test for sysctl"
depends on KUNIT
help
This builds the proc sysctl unit test, which runs on boot.
Tests the API contract and implementation correctness of sysctl.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config TEST_UDELAY
tristate "udelay test driver"
help