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

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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: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Sandeen 2019-05-14 15:45:10 -07:00 • committed by Linus Torvalds
parent a0edef7968
commit 2ea622b887
2 changed files with 97 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
lib/test_sysctl.c
View file

@ -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_sysctl_header = register_sysctl_table(test_sysctl_root_table);
if (!test_sysctl_header)
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) {
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);
}

81
tools/testing/selftests/sysctl/sysctl.sh
View file

@ -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