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Commit 24fe831c authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

tools/testing/selftests/sysctl: validate sysctl_writes_strict 



This adds several behavioral tests to sysctl string and number writing
to detect unexpected cases that behaved differently when the sysctl
kernel.sysctl_writes_strict != 1.

[ original ]
    root@localhost:~# make test_num
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... FAIL
    Writing entire sysctl in short writes ... FAIL
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... FAIL
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    make: *** [test_num] Error 1
    root@localhost:~# make test_string
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... ok
    make: *** [test_string] Error 1

[ with CONFIG_PROC_SYSCTL_STRICT_WRITES ]
    root@localhost:~# make run_tests
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok
    Writing entire sysctl in short writes ... ok
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... ok
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f4aacea2

tools/testing/selftests/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ TARGETS += timers 
TARGETS += vm

TARGETS += powerpc

TARGETS += user

TARGETS += sysctl



all:

	for TARGET in $(TARGETS); do \

tools/testing/selftests/sysctl/Makefile

0 → 100644
+19 −0
Original line number Diff line number Diff line 
# Makefile for sysctl selftests.

# Expects kernel.sysctl_writes_strict=1.



# No binaries, but make sure arg-less "make" doesn't trigger "run_tests".

all:



# Allow specific tests to be selected.

test_num:

	@/bin/sh ./run_numerictests



test_string:

	@/bin/sh ./run_stringtests



run_tests: all test_num test_string



# Nothing to clean up.

clean:



.PHONY: all run_tests clean test_num test_string

tools/testing/selftests/sysctl/common_tests

0 → 100644
+109 −0
Original line number Diff line number Diff line 
#!/bin/sh



TEST_FILE=$(mktemp)



echo "== Testing sysctl behavior against ${TARGET} =="



set_orig()

{

	echo "${ORIG}" > "${TARGET}"

}



set_test()

{

	echo "${TEST_STR}" > "${TARGET}"

}



verify()

{

	local seen

	seen=$(cat "$1")

	if [ "${seen}" != "${TEST_STR}" ]; then

		return 1

	fi

	return 0

}



trap 'set_orig; rm -f "${TEST_FILE}"' EXIT



rc=0



echo -n "Writing test file ... "

echo "${TEST_STR}" > "${TEST_FILE}"

if ! verify "${TEST_FILE}"; then

	echo "FAIL" >&2

	exit 1

else

	echo "ok"

fi



echo -n "Checking sysctl is not set to test value ... "

if verify "${TARGET}"; then

	echo "FAIL" >&2

	exit 1

else

	echo "ok"

fi



echo -n "Writing sysctl from shell ... "

set_test

if ! verify "${TARGET}"; then

	echo "FAIL" >&2

	exit 1

else

	echo "ok"

fi



echo -n "Resetting sysctl to original value ... "

set_orig

if verify "${TARGET}"; then

	echo "FAIL" >&2

	exit 1

else

	echo "ok"

fi



# Now that we've validated the sanity of "set_test" and "set_orig",

# we can use those functions to set starting states before running

# specific behavioral tests.



echo -n "Writing entire sysctl in single write ... "

set_orig

dd if="${TEST_FILE}" of="${TARGET}" bs=4096 2>/dev/null

if ! verify "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Writing middle of sysctl after synchronized seek ... "

set_test

dd if="${TEST_FILE}" of="${TARGET}" bs=1 seek=1 skip=1 2>/dev/null

if ! verify "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Writing beyond end of sysctl ... "

set_orig

dd if="${TEST_FILE}" of="${TARGET}" bs=20 seek=2 2>/dev/null

if verify "${TARGET}"; then

        echo "FAIL" >&2

        rc=1

else

        echo "ok"

fi



echo -n "Writing sysctl with multiple long writes ... "

set_orig

(perl -e 'print "A" x 50;'; echo "${TEST_STR}") | \

	dd of="${TARGET}" bs=50 2>/dev/null

if verify "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi

tools/testing/selftests/sysctl/run_numerictests

0 → 100644
+10 −0
Original line number Diff line number Diff line 
#!/bin/sh



SYSCTL="/proc/sys"

TARGET="${SYSCTL}/vm/swappiness"

ORIG=$(cat "${TARGET}")

TEST_STR=$(( $ORIG + 1 ))



. ./common_tests



exit $rc

tools/testing/selftests/sysctl/run_stringtests

0 → 100644
+77 −0
Original line number Diff line number Diff line 
#!/bin/sh



SYSCTL="/proc/sys"

TARGET="${SYSCTL}/kernel/domainname"

ORIG=$(cat "${TARGET}")

TEST_STR="Testing sysctl"



. ./common_tests



# Only string sysctls support seeking/appending.

MAXLEN=65



echo -n "Writing entire sysctl in short writes ... "

set_orig

dd if="${TEST_FILE}" of="${TARGET}" bs=1 2>/dev/null

if ! verify "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Writing middle of sysctl after unsynchronized seek ... "

set_test

dd if="${TEST_FILE}" of="${TARGET}" bs=1 seek=1 2>/dev/null

if verify "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Checking sysctl maxlen is at least $MAXLEN ... "

set_orig

perl -e 'print "A" x ('"${MAXLEN}"'-2), "B";' | \

	dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null

if ! grep -q B "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Checking sysctl keeps original string on overflow append ... "

set_orig

perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \

	dd of="${TARGET}" bs=$(( MAXLEN - 1 )) 2>/dev/null

if grep -q B "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Checking sysctl stays NULL terminated on write ... "

set_orig

perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \

	dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null

if grep -q B "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



echo -n "Checking sysctl stays NULL terminated on overwrite ... "

set_orig

perl -e 'print "A" x ('"${MAXLEN}"'-1), "BB";' | \

	dd of="${TARGET}" bs=$(( $MAXLEN + 1 )) 2>/dev/null

if grep -q B "${TARGET}"; then

	echo "FAIL" >&2

	rc=1

else

	echo "ok"

fi



exit $rc