commit ce854a8d22d5056cc1a47a0d4d4251f93a0c667c Author: Nick Mathewson nickm@torproject.org Date: Tue Apr 12 18:59:40 2016 -0400
Add -ftrapv to gcc-hardening ... mostly!
We know there are overflows in curve25519-donna-c32, so we'll have to have that one be fwrapv.
Only apply the asan, ubsan, and trapv options to the code that does not need to run in constant time. Those options introduce branches to the code they instrument.
(These introduced branches should never actually be taken, so it might _still_ be constant time after all, but branch predictors are complicated enough that I'm not really confident here. Let's aim for safety.)
Closes 17983. --- .gitignore | 3 +++ Makefile.am | 4 ++-- acinclude.m4 | 20 +++++++++++++++----- changes/bug17983 | 11 +++++++++++ configure.ac | 23 ++++++++++++++++++++--- src/common/include.am | 17 ++++++++++++++--- src/ext/include.am | 9 ++++++--- src/or/include.am | 3 ++- src/test/include.am | 6 ++++++ src/tools/include.am | 11 +++++++++-- 10 files changed, 88 insertions(+), 19 deletions(-)
diff --git a/.gitignore b/.gitignore index b141e80..7103dbe 100644 --- a/.gitignore +++ b/.gitignore @@ -132,6 +132,9 @@ uptime-*.json /src/common/libor.a /src/common/libor-testing.a /src/common/libor.lib +/src/common/libor-ctime.a +/src/common/libor-ctime-testing.a +/src/common/libor-ctime.lib /src/common/libor-crypto.a /src/common/libor-crypto-testing.a /src/common/libor-crypto.lib diff --git a/Makefile.am b/Makefile.am index 92ba2b8..e9abfc6 100644 --- a/Makefile.am +++ b/Makefile.am @@ -15,8 +15,8 @@ noinst_PROGRAMS= DISTCLEANFILES= bin_SCRIPTS= AM_CPPFLAGS= -AM_CFLAGS = @TOR_SYSTEMD_CFLAGS@ -SHELL = @SHELL@ +AM_CFLAGS=@TOR_SYSTEMD_CFLAGS@ @CFLAGS_BUGTRAP@ +SHELL=@SHELL@
if COVERAGE_ENABLED TESTING_TOR_BINARY="$(top_builddir)/src/or/tor-cov" diff --git a/acinclude.m4 b/acinclude.m4 index 7b1aab2..4b9f095 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -42,10 +42,11 @@ AC_DEFUN([TOR_DEFINE_CODEPATH], AC_SUBST(TOR_LDFLAGS_$2) ])
-dnl 1:flags -dnl 2:also try to link (yes: non-empty string) -dnl will set yes or no in $tor_can_link_$1 (as modified by AS_VAR_PUSHDEF) -AC_DEFUN([TOR_CHECK_CFLAGS], [ +dnl 1: flags +dnl 2: try to link too if this is nonempty. +dnl 3: what to do on success compiling +dnl 4: what to do on failure compiling +AC_DEFUN([TOR_TRY_COMPILE_WITH_CFLAGS], [ AS_VAR_PUSHDEF([VAR],[tor_cv_cflags_$1]) AC_CACHE_CHECK([whether the compiler accepts $1], VAR, [ tor_saved_CFLAGS="$CFLAGS" @@ -63,12 +64,21 @@ AC_DEFUN([TOR_CHECK_CFLAGS], [ CFLAGS="$tor_saved_CFLAGS" ]) if test x$VAR = xyes; then - CFLAGS="$CFLAGS $1" + $3 + else + $4 fi AS_VAR_POPDEF([VAR]) ])
dnl 1:flags +dnl 2:also try to link (yes: non-empty string) +dnl will set yes or no in $tor_can_link_$1 (as modified by AS_VAR_PUSHDEF) +AC_DEFUN([TOR_CHECK_CFLAGS], [ + TOR_TRY_COMPILE_WITH_CFLAGS($1, $2, CFLAGS="$CFLAGS $1", /bin/true) +]) + +dnl 1:flags dnl 2:extra ldflags dnl 3:extra libraries AC_DEFUN([TOR_CHECK_LDFLAGS], [ diff --git a/changes/bug17983 b/changes/bug17983 new file mode 100644 index 0000000..db52a37 --- /dev/null +++ b/changes/bug17983 @@ -0,0 +1,11 @@ + o Minor features (bug-finding): + - Tor now builds with -ftrapv by default on compilers that support it. + This option detects signed integer overflow, and turns it into a + hard-failure. We do not apply this option to code that needs to run + in constant time to avoid side-channels; instead, we use -fwrapv. + Closes ticket 17983. + - When --enable-expensive-hardening is selected, stop applying the clang/gcc + sanitizers to code that needs to run in constant-time to avoid side + channels: although we are aware of no introduced side-channels, we + are not able to prove that this is safe. Related to ticket 17983. + diff --git a/configure.ac b/configure.ac index 4bdd2d3..626be6c 100644 --- a/configure.ac +++ b/configure.ac @@ -755,6 +755,11 @@ dnl use it with a build of a library. all_ldflags_for_check="$TOR_LDFLAGS_zlib $TOR_LDFLAGS_openssl $TOR_LDFLAGS_libevent" all_libs_for_check="$TOR_ZLIB_LIBS $TOR_LIB_MATH $TOR_LIBEVENT_LIBS $TOR_OPENSSL_LIBS $TOR_SYSTEMD_LIBS $TOR_LIB_WS32 $TOR_LIB_GDI $TOR_CAP_LIBS"
+CFLAGS_FTRAPV= +CFLAGS_FWRAPV= +CFLAGS_ASAN= +CFLAGS_UBSAN= + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [ #if !defined(__clang__) #error @@ -777,20 +782,32 @@ m4_ifdef([AS_VAR_IF],[ AS_VAR_POPDEF([can_link]) AS_VAR_POPDEF([can_compile]) TOR_CHECK_CFLAGS(-Wstack-protector) - TOR_CHECK_CFLAGS(-fwrapv) TOR_CHECK_CFLAGS(--param ssp-buffer-size=1) if test "$bwin32" = "false"; then TOR_CHECK_CFLAGS(-fPIE) TOR_CHECK_LDFLAGS(-pie, "$all_ldflags_for_check", "$all_libs_for_check") fi + TOR_TRY_COMPILE_WITH_CFLAGS(-ftrapv, , CFLAGS_FTRAPV="-ftrapv", /bin/true) + TOR_TRY_COMPILE_WITH_CFLAGS(-fwrapv, , CFLAGS_FWRAPV="-fwrapv", /bin/true) fi
if test "x$enable_expensive_hardening" = "xyes"; then - TOR_CHECK_CFLAGS([-fsanitize=address]) - TOR_CHECK_CFLAGS([-fsanitize=undefined]) + TOR_TRY_COMPILE_WITH_CFLAGS([-fsanitize=address], , CFLAGS_ASAN="-fsanitize=address", /bin/true) + TOR_TRY_COMPILE_WITH_CFLAGS([-fsanitize=undefined], , CFLAGS_UBSAN="-fsanitize=undefined", /bin/true) TOR_CHECK_CFLAGS([-fno-omit-frame-pointer]) fi
+CFLAGS_BUGTRAP="$CFLAGS_FTRAPV $CFLAGS_ASAN $CFLAGS_UBSAN" +CFLAGS_CONSTTIME="$CFLAGS_FWRAPV" + +dnl These cflags add bunches of branches, and we haven't been able to +dnl persuade ourselves that they're suitable for code that needs to be +dnl constant time. +AC_SUBST(CFLAGS_BUGTRAP) +dnl These cflags are variant ones sutable for code that needs to be +dnl constant-time. +AC_SUBST(CFLAGS_CONSTTIME) + if test "x$enable_linker_hardening" != "xno"; then TOR_CHECK_LDFLAGS(-z relro -z now, "$all_ldflags_for_check", "$all_libs_for_check") fi diff --git a/src/common/include.am b/src/common/include.am index 5afb30d..96fc329 100644 --- a/src/common/include.am +++ b/src/common/include.am @@ -1,12 +1,14 @@
noinst_LIBRARIES += \ src/common/libor.a \ + src/common/libor-ctime.a \ src/common/libor-crypto.a \ src/common/libor-event.a
if UNITTESTS_ENABLED noinst_LIBRARIES += \ src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ src/common/libor-crypto-testing.a \ src/common/libor-event-testing.a endif @@ -27,12 +29,14 @@ src_common_libcurve25519_donna_a_CFLAGS= if BUILD_CURVE25519_DONNA src_common_libcurve25519_donna_a_SOURCES=\ src/ext/curve25519_donna/curve25519-donna.c +# See bug 13538 -- this code is known to have signed overflow issues. src_common_libcurve25519_donna_a_CFLAGS+=\ - @F_OMIT_FRAME_POINTER@ + @F_OMIT_FRAME_POINTER@ @CFLAGS_CONSTTIME@ noinst_LIBRARIES+=src/common/libcurve25519_donna.a LIBDONNA=src/common/libcurve25519_donna.a else if BUILD_CURVE25519_DONNA_C64 +src_common_libcurve25519_donna_a_CFLAGS+=@CFLAGS_CONSTTIME@ src_common_libcurve25519_donna_a_SOURCES=\ src/ext/curve25519_donna/curve25519-donna-c64.c noinst_LIBRARIES+=src/common/libcurve25519_donna.a @@ -58,13 +62,21 @@ else readpassphrase_source= endif
+LIBOR_CTIME_A_SOURCES = \ + src/ext/csiphash.c \ + src/common/di_ops.c + +src_common_libor_ctime_a_SOURCES = $(LIBOR_CTIME_A_SOURCES) +src_common_libor_ctime_testing_a_SOURCES = $(LIBOR_CTIME_A_SOURCES) +src_common_libor_ctime_a_CFLAGS = @CFLAGS_CONSTTIME@ +src_common_libor_ctime_testing_a_CFLAGS = @CFLAGS_CONSTTIME@ $(TEST_CFLAGS) + LIBOR_A_SOURCES = \ src/common/address.c \ src/common/backtrace.c \ src/common/compat.c \ src/common/compat_threads.c \ src/common/container.c \ - src/common/di_ops.c \ src/common/log.c \ src/common/memarea.c \ src/common/util.c \ @@ -72,7 +84,6 @@ LIBOR_A_SOURCES = \ src/common/util_process.c \ src/common/sandbox.c \ src/common/workqueue.c \ - src/ext/csiphash.c \ src/ext/trunnel/trunnel.c \ $(libor_extra_source) \ $(threads_impl_source) \ diff --git a/src/ext/include.am b/src/ext/include.am index bf678f2..2a0227a 100644 --- a/src/ext/include.am +++ b/src/ext/include.am @@ -16,7 +16,8 @@ EXTHEADERS = \
noinst_HEADERS+= $(EXTHEADERS)
-src_ext_ed25519_ref10_libed25519_ref10_a_CFLAGS= +src_ext_ed25519_ref10_libed25519_ref10_a_CFLAGS=\ + @CFLAGS_CONSTTIME@
src_ext_ed25519_ref10_libed25519_ref10_a_SOURCES= \ src/ext/ed25519/ref10/fe_0.c \ @@ -93,7 +94,8 @@ noinst_HEADERS += $(ED25519_REF10_HDRS) LIBED25519_REF10=src/ext/ed25519/ref10/libed25519_ref10.a noinst_LIBRARIES += $(LIBED25519_REF10)
-src_ext_ed25519_donna_libed25519_donna_a_CFLAGS= \ +src_ext_ed25519_donna_libed25519_donna_a_CFLAGS=\ + @CFLAGS_CONSTTIME@ \ -DED25519_CUSTOMRANDOM \ -DED25519_SUFFIX=_donna
@@ -135,7 +137,8 @@ noinst_HEADERS += $(ED25519_DONNA_HDRS) LIBED25519_DONNA=src/ext/ed25519/donna/libed25519_donna.a noinst_LIBRARIES += $(LIBED25519_DONNA)
-src_ext_keccak_tiny_libkeccak_tiny_a_CFLAGS= +src_ext_keccak_tiny_libkeccak_tiny_a_CFLAGS=\ + @CFLAGS_CONSTTIME@
src_ext_keccak_tiny_libkeccak_tiny_a_SOURCES= \ src/ext/keccak-tiny/keccak-tiny-unrolled.c diff --git a/src/or/include.am b/src/or/include.am index 712ae18..19f1a7f 100644 --- a/src/or/include.am +++ b/src/or/include.am @@ -109,7 +109,7 @@ src_or_libtor_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
src_or_tor_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ @TOR_LDFLAGS_libevent@ -src_or_tor_LDADD = src/or/libtor.a src/common/libor.a \ +src_or_tor_LDADD = src/or/libtor.a src/common/libor.a src/common/libor-ctime.a \ src/common/libor-crypto.a $(LIBKECCAK_TINY) $(LIBDONNA) \ src/common/libor-event.a src/trunnel/libor-trunnel.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ @TOR_OPENSSL_LIBS@ \ @@ -121,6 +121,7 @@ src_or_tor_cov_CPPFLAGS = $(AM_CPPFLAGS) $(TEST_CPPFLAGS) src_or_tor_cov_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS) src_or_tor_cov_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ @TOR_LDFLAGS_libevent@ src_or_tor_cov_LDADD = src/or/libtor-testing.a src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ src/common/libor-crypto-testing.a $(LIBKECCAK_TINY) $(LIBDONNA) \ src/common/libor-event-testing.a src/trunnel/libor-trunnel-testing.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ @TOR_OPENSSL_LIBS@ \ diff --git a/src/test/include.am b/src/test/include.am index 7d80fdf..c4ef30f 100644 --- a/src/test/include.am +++ b/src/test/include.am @@ -147,6 +147,7 @@ src_test_test_switch_id_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS) src_test_test_switch_id_LDFLAGS = @TOR_LDFLAGS_zlib@ src_test_test_switch_id_LDADD = \ src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@
src_test_test_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \ @@ -156,6 +157,7 @@ src_test_test_LDADD = src/or/libtor-testing.a \ $(LIBKECCAK_TINY) \ $(LIBDONNA) \ src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ src/common/libor-event-testing.a \ src/trunnel/libor-trunnel-testing.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \ @@ -175,6 +177,7 @@ src_test_test_memwipe_LDFLAGS = $(src_test_test_LDFLAGS) src_test_bench_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \ @TOR_LDFLAGS_libevent@ src_test_bench_LDADD = src/or/libtor.a src/common/libor.a \ + src/common/libor-ctime.a \ src/common/libor-crypto.a $(LIBKECCAK_TINY) $(LIBDONNA) \ src/common/libor-event.a src/trunnel/libor-trunnel.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \ @@ -185,6 +188,7 @@ src_test_test_workqueue_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \ @TOR_LDFLAGS_libevent@ src_test_test_workqueue_LDADD = src/or/libtor-testing.a \ src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ src/common/libor-crypto-testing.a $(LIBKECCAK_TINY) $(LIBDONNA) \ src/common/libor-event-testing.a \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \ @@ -208,6 +212,7 @@ noinst_PROGRAMS+= src/test/test-ntor-cl src_test_test_ntor_cl_SOURCES = src/test/test_ntor_cl.c src_test_test_ntor_cl_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ src_test_test_ntor_cl_LDADD = src/or/libtor.a src/common/libor.a \ + src/common/libor-ctime.a \ src/common/libor-crypto.a $(LIBKECCAK_TINY) $(LIBDONNA) \ @TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \ @TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ @@ -217,6 +222,7 @@ src_test_test_ntor_cl_AM_CPPFLAGS = \ noinst_PROGRAMS += src/test/test-bt-cl src_test_test_bt_cl_SOURCES = src/test/test_bt_cl.c src_test_test_bt_cl_LDADD = src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ @TOR_LIB_MATH@ \ @TOR_LIB_WS32@ @TOR_LIB_GDI@ src_test_test_bt_cl_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS) diff --git a/src/tools/include.am b/src/tools/include.am index 38ed575..b4ea82d 100644 --- a/src/tools/include.am +++ b/src/tools/include.am @@ -7,19 +7,23 @@ endif
src_tools_tor_resolve_SOURCES = src/tools/tor-resolve.c src_tools_tor_resolve_LDFLAGS = -src_tools_tor_resolve_LDADD = src/common/libor.a @TOR_LIB_MATH@ @TOR_LIB_WS32@ +src_tools_tor_resolve_LDADD = src/common/libor.a \ + src/common/libor-ctime.a \ + @TOR_LIB_MATH@ @TOR_LIB_WS32@
if COVERAGE_ENABLED src_tools_tor_cov_resolve_SOURCES = src/tools/tor-resolve.c src_tools_tor_cov_resolve_CPPFLAGS = $(AM_CPPFLAGS) $(TEST_CPPFLAGS) src_tools_tor_cov_resolve_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS) src_tools_tor_cov_resolve_LDADD = src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ @TOR_LIB_MATH@ @TOR_LIB_WS32@ endif
src_tools_tor_gencert_SOURCES = src/tools/tor-gencert.c src_tools_tor_gencert_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ src_tools_tor_gencert_LDADD = src/common/libor.a src/common/libor-crypto.a \ + src/common/libor-ctime.a \ $(LIBKECCAK_TINY) \ $(LIBDONNA) \ @TOR_LIB_MATH@ @TOR_ZLIB_LIBS@ @TOR_OPENSSL_LIBS@ \ @@ -31,6 +35,7 @@ src_tools_tor_cov_gencert_CPPFLAGS = $(AM_CPPFLAGS) $(TEST_CPPFLAGS) src_tools_tor_cov_gencert_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS) src_tools_tor_cov_gencert_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ src_tools_tor_cov_gencert_LDADD = src/common/libor-testing.a \ + src/common/libor-ctime-testing.a \ src/common/libor-crypto-testing.a \ $(LIBKECCAK_TINY) \ $(LIBDONNA) \ @@ -40,7 +45,9 @@ endif
src_tools_tor_checkkey_SOURCES = src/tools/tor-checkkey.c src_tools_tor_checkkey_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ -src_tools_tor_checkkey_LDADD = src/common/libor.a src/common/libor-crypto.a \ +src_tools_tor_checkkey_LDADD = src/common/libor.a \ + src/common/libor-ctime.a \ + src/common/libor-crypto.a \ $(LIBKECCAK_TINY) \ $(LIBDONNA) \ @TOR_LIB_MATH@ @TOR_ZLIB_LIBS@ @TOR_OPENSSL_LIBS@ \