test_sysctl: test against PAGE_SIZE for int

Add the following tests to ensure we do not regress:

  o Test using a buffer full of space (PAGE_SIZE-1) followed by a
    single digit works

  o Test using a buffer full of spaces (PAGE_SIZE or over) will fail

As tests increase instead of unloading the module and reloading it we
can just do a shell reset_vals() with a reset to values we know are set
at init on the driver.

Link: http://lkml.kernel.org/r/20170630224431.17374-4-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/sysctl/sysctl.sh b/tools/testing/selftests/sysctl/sysctl.sh
index cbe1345d7c1d78db0b99cebfbcf3002a7384c550..6ec807576f7c996eae7e703bcce636e052162b54 100644 (file)
--- a/tools/testing/selftests/sysctl/sysctl.sh
+++ b/tools/testing/selftests/sysctl/sysctl.sh
@@ -75,6 +75,13 @@ function check_production_sysctl_writes_strict()
                        echo "1" > ${WRITES_STRICT}
                fi
        fi
+
+       if [ -z $PAGE_SIZE ]; then
+               PAGE_SIZE=$(getconf PAGESIZE)
+       fi
+       if [ -z $MAX_DIGITS ]; then
+               MAX_DIGITS=$(($PAGE_SIZE/8))
+       fi
 }
 
 test_reqs()
@@ -89,6 +96,10 @@ test_reqs()
                echo "$0: You need perl installed"
                exit 1
        fi
+       if ! which getconf 2> /dev/null > /dev/null; then
+               echo "$0: You need getconf installed"
+               exit 1
+       fi
 }
 
 function load_req_mod()
@@ -103,6 +114,23 @@ function load_req_mod()
        fi
 }
 
+reset_vals()
+{
+       VAL=""
+       TRIGGER=$(basename ${TARGET})
+       case "$TRIGGER" in
+               int_0001)
+                       VAL="60"
+                       ;;
+               string_0001)
+                       VAL="(none)"
+                       ;;
+               *)
+                       ;;
+       esac
+       echo -n $VAL > $TARGET
+}
+
 set_orig()
 {
        if [ ! -z $TARGET ]; then
@@ -229,7 +257,42 @@ run_numerictests()
        else
                echo "ok"
        fi
+       test_rc
+}
+
+# Your test must accept digits 3 and 4 to use this
+run_limit_digit()
+{
+       echo -n "Checking ignoring spaces up to PAGE_SIZE works on write ..."
+       reset_vals
 
+       LIMIT=$((MAX_DIGITS -1))
+       TEST_STR="3"
+       (perl -e 'print " " x '$LIMIT';'; echo "${TEST_STR}") | \
+               dd of="${TARGET}" 2>/dev/null
+
+       if ! verify "${TARGET}"; then
+               echo "FAIL" >&2
+               rc=1
+       else
+               echo "ok"
+       fi
+       test_rc
+
+       echo -n "Checking passing PAGE_SIZE of spaces fails on write ..."
+       reset_vals
+
+       LIMIT=$((MAX_DIGITS))
+       TEST_STR="4"
+       (perl -e 'print " " x '$LIMIT';'; echo "${TEST_STR}") | \
+               dd of="${TARGET}" 2>/dev/null
+
+       if verify "${TARGET}"; then
+               echo "FAIL" >&2
+               rc=1
+       else
+               echo "ok"
+       fi
        test_rc
 }
 
@@ -305,15 +368,18 @@ run_stringtests()
 sysctl_test_0001()
 {
        TARGET="${SYSCTL}/int_0001"
+       reset_vals
        ORIG=$(cat "${TARGET}")
        TEST_STR=$(( $ORIG + 1 ))
 
        run_numerictests
+       run_limit_digit
 }
 
 sysctl_test_0002()
 {
        TARGET="${SYSCTL}/string_0001"
+       reset_vals
        ORIG=$(cat "${TARGET}")
        TEST_STR="Testing sysctl"
        # Only string sysctls support seeking/appending.