Make sure we don't regress the CAP_SYSLOG behavior of the module address visibility via /proc/modules nor /sys/module/*/sections/*.

Cc: Luis Chamberlain mcgrof@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org --- I forgot to include this patch in my kallsyms_show_value() f_cred series: https://lore.kernel.org/lkml/20200702232638.2946421-1-keescook@chromium.org/ Since this depends on the changes, I'd like to include this in the series with acks/review, etc. :) --- tools/testing/selftests/kmod/kmod.sh | 36 ++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)

diff --git a/tools/testing/selftests/kmod/kmod.sh b/tools/testing/selftests/kmod/kmod.sh index 3702dbcc90a7..c82aa77958e5 100755 --- a/tools/testing/selftests/kmod/kmod.sh +++ b/tools/testing/selftests/kmod/kmod.sh @@ -63,6 +63,8 @@ ALL_TESTS="$ALL_TESTS 0008:150:1" ALL_TESTS="$ALL_TESTS 0009:150:1" ALL_TESTS="$ALL_TESTS 0010:1:1" ALL_TESTS="$ALL_TESTS 0011:1:1" +ALL_TESTS="$ALL_TESTS 0012:1:1" +ALL_TESTS="$ALL_TESTS 0013:1:1"

# Kselftest framework requirement - SKIP code is 4. ksft_skip=4 @@ -470,6 +472,38 @@ kmod_test_0011() echo "$MODPROBE" > /proc/sys/kernel/modprobe }

+kmod_check_visibility() +{ + local name="$1" + local cmd="$2" + + modprobe $DEFAULT_KMOD_DRIVER + + local priv=$(eval $cmd) + local unpriv=$(capsh --drop=CAP_SYSLOG -- -c "$cmd") + + if [ "$priv" = "$unpriv" ] || \ + [ "${priv:0:3}" = "0x0" ] || \ + [ "${unpriv:0:3}" != "0x0" ] ; then + echo "${FUNCNAME[0]}: FAIL, $name visible to unpriv: '$priv' vs '$unpriv'" >&2 + exit 1 + else + echo "${FUNCNAME[0]}: OK!" + fi +} + +kmod_test_0012() +{ + kmod_check_visibility /proc/modules \ + "grep '^${DEFAULT_KMOD_DRIVER}\b' /proc/modules | awk '{print $NF}'" +} + +kmod_test_0013() +{ + kmod_check_visibility '/sys/module/*/sections/*' \ + "cat /sys/module/${DEFAULT_KMOD_DRIVER}/sections/.*text | head -n1" +} + list_tests() { echo "Test ID list:" @@ -489,6 +523,8 @@ list_tests() echo "0009 x $(get_test_count 0009) - multithreaded - push kmod_concurrent over max_modprobes for get_fs_type()" echo "0010 x $(get_test_count 0010) - test nonexistent modprobe path" echo "0011 x $(get_test_count 0011) - test completely disabling module autoloading" + echo "0012 x $(get_test_count 0012) - test /proc/modules address visibility under CAP_SYSLOG" + echo "0013 x $(get_test_count 0013) - test /sys/module/*/sections/* visibility under CAP_SYSLOG" }

usage()