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Commit 2ea622b8 authored by Eric Sandeen's avatar Eric Sandeen Committed by Linus Torvalds
Browse files

tools/testing/selftests/sysctl/sysctl.sh: add proc_do_large_bitmap() test case 

The kernel has only two users of proc_do_large_bitmap(), the kernel CPU
watchdog, and the ip_local_reserved_ports.  Refer to watchdog_cpumask
and ip_local_reserved_ports in Documentation for further details on
these.  When you input a large buffer into these, when it is larger than
PAGE_SIZE- 1, the input data gets misparsed, and the user get
incorrectly informed that the desired input value was set.  This commit
implements a test which mimics and exploits that use case, it uses a
bitmap size, as in the watchdog case.  The bitmap is used to test the
bitmap proc handler, proc_do_large_bitmap().

The next commit fixes this issue.

[akpm@linux-foundation.org: move proc_do_large_bitmap() export to EOF]
[mcgrof@kernel.org: use new target description for backward compatibility]
[mcgrof@kernel.org: augment test number to 50, ran into issues with bash string comparisons when testing up to 50 cases.]
[mcgrof@kernel.org: introduce and use verify_diff_proc_file() to use diff]
[mcgrof@kernel.org: use mktemp for tmp file]
[mcgrof@kernel.org: merge shell test and C code]
[mcgrof@kernel.org: commit log love]
[mcgrof@kernel.org: export proc_do_large_bitmap() to allow for the test
[mcgrof@kernel.org: check for the return value when writing to the proc file]
Link: http://lkml.kernel.org/r/20190320222831.8243-6-mcgrof@kernel.org


Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a0edef79

lib/test_sysctl.c

+17 −1
Original line number Diff line number Diff line
@@ -47,6 +47,9 @@ struct test_sysctl_data { 
	unsigned int uint_0001;



	char string_0001[65];



#define SYSCTL_TEST_BITMAP_SIZE	65536

	unsigned long *bitmap_0001;

};



static struct test_sysctl_data test_data = {
@@ -102,6 +105,13 @@ static struct ctl_table test_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dostring,

	},

	{

		.procname	= "bitmap_0001",

		.data		= &test_data.bitmap_0001,

		.maxlen		= SYSCTL_TEST_BITMAP_SIZE,

		.mode		= 0644,

		.proc_handler	= proc_do_large_bitmap,

	},

	{ }

};
@@ -129,15 +139,21 @@ static struct ctl_table_header *test_sysctl_header; 


static int __init test_sysctl_init(void)

{

	test_data.bitmap_0001 = kzalloc(SYSCTL_TEST_BITMAP_SIZE/8, GFP_KERNEL);

	if (!test_data.bitmap_0001)

		return -ENOMEM;

	test_sysctl_header = register_sysctl_table(test_sysctl_root_table);

	if (!test_sysctl_header)

	if (!test_sysctl_header) {

		kfree(test_data.bitmap_0001);

		return -ENOMEM;

	}

	return 0;

}

late_initcall(test_sysctl_init);



static void __exit test_sysctl_exit(void)

{

	kfree(test_data.bitmap_0001);

	if (test_sysctl_header)

		unregister_sysctl_table(test_sysctl_header);

}

tools/testing/selftests/sysctl/sysctl.sh

+79 −2
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ ALL_TESTS="$ALL_TESTS 0002:1:1:string_0001" 
ALL_TESTS="$ALL_TESTS 0003:1:1:int_0002"

ALL_TESTS="$ALL_TESTS 0004:1:1:uint_0001"

ALL_TESTS="$ALL_TESTS 0005:3:1:int_0003"

ALL_TESTS="$ALL_TESTS 0006:50:1:bitmap_0001"



test_modprobe()

{
@@ -150,6 +151,9 @@ reset_vals() 
		string_0001)

			VAL="(none)"

			;;

		bitmap_0001)

			VAL=""

			;;

		*)

			;;

	esac
@@ -180,6 +184,22 @@ verify() 
	return 0

}



# proc files get read a page at a time, which can confuse diff,

# and get you incorrect results on proc files with long data. To use

# diff against them you must first extract the output to a file, and

# then compare against that file.

verify_diff_proc_file()

{

	TMP_DUMP_FILE=$(mktemp)

	cat $1 > $TMP_DUMP_FILE



	if ! diff -w -q $TMP_DUMP_FILE $2; then

		return 1

	else

		return 0

	fi

}



verify_diff_w()

{

	echo "$TEST_STR" | diff -q -w -u - $1 > /dev/null
@@ -615,6 +635,55 @@ target_exists() 
	return 1

}



run_bitmaptest() {

	# Total length of bitmaps string to use, a bit under

	# the maximum input size of the test node

	LENGTH=$((RANDOM % 65000))



	# First bit to set

	BIT=$((RANDOM % 1024))



	# String containing our list of bits to set

	TEST_STR=$BIT



	# build up the string

	while [ "${#TEST_STR}" -le "$LENGTH" ]; do

		# Make sure next entry is discontiguous,

		# skip ahead at least 2

		BIT=$((BIT + $((2 + RANDOM % 10))))



		# Add new bit to the list

		TEST_STR="${TEST_STR},${BIT}"



		# Randomly make it a range

		if [ "$((RANDOM % 2))" -eq "1" ]; then

			RANGE_END=$((BIT + $((1 + RANDOM % 10))))

			TEST_STR="${TEST_STR}-${RANGE_END}"

			BIT=$RANGE_END

		fi

	done



	echo -n "Checking bitmap handler... "

	TEST_FILE=$(mktemp)

	echo -n "$TEST_STR" > $TEST_FILE



	cat $TEST_FILE > $TARGET 2> /dev/null

	if [ $? -ne 0 ]; then

		echo "FAIL" >&2

		rc=1

		test_rc

	fi



	if ! verify_diff_proc_file "$TARGET" "$TEST_FILE"; then

		echo "FAIL" >&2

		rc=1

	else

		echo "ok"

		rc=0

	fi

	test_rc

}



sysctl_test_0001()

{

	TARGET="${SYSCTL}/$(get_test_target 0001)"
@@ -675,6 +744,14 @@ sysctl_test_0005() 
	run_limit_digit_int_array

}



sysctl_test_0006()

{

	TARGET="${SYSCTL}/bitmap_0001"

	reset_vals

	ORIG=""

	run_bitmaptest

}



list_tests()

{

	echo "Test ID list:"
@@ -688,6 +765,7 @@ list_tests() 
	echo "0003 x $(get_test_count 0003) - tests proc_dointvec()"

	echo "0004 x $(get_test_count 0004) - tests proc_douintvec()"

	echo "0005 x $(get_test_count 0005) - tests proc_douintvec() array"

	echo "0006 x $(get_test_count 0006) - tests proc_do_large_bitmap()"

}



usage()
@@ -761,8 +839,7 @@ function run_all_tests() 
		ENABLED=$(get_test_enabled $TEST_ID)

		TEST_COUNT=$(get_test_count $TEST_ID)

		TEST_TARGET=$(get_test_target $TEST_ID)

		target_exists $TEST_TARGET $TEST_ID

		if [ $? -ne 1 ]; then

		if target_exists $TEST_TARGET $TEST_ID; then

			continue

		fi

		if [[ $ENABLED -eq "1" ]]; then