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: 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>

diff --git a/lib/test_sysctl.c b/lib/test_sysctl.c
index 3dd801c..566dad3 100644 (file)
--- a/lib/test_sysctl.c
+++ b/lib/test_sysctl.c
@@ -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);
 }

diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index 4eb0190..6a970b1 100755 (executable)
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -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