drbg: add thread-safe option, --disable-threadsafe-drbg to opt out

.github/configs/os-check-linux.json

@@ -287,7 +287,19 @@
  "configure": ["--enable-she=standard", "--enable-cmac"]},
 {"name": "no-verify-oid-fpki", "minutes": 1.2,
  "configure": ["CPPFLAGS=-DNO_VERIFY_OID -DWOLFSSL_FPKI"]},
+{"name": "rng-atfork-off", "minutes": 1.2,
+ "comment": "Opt out of the RNG fork handlers that are on by default, so the lock without them is built and tested.",
+ "configure": ["--disable-rng-atfork"]},
+{"name": "rng-no-getpid", "minutes": 1.5,
+ "comment": "Default RNG fork handlers without the pid check, so the child handler alone must make the forked child reseed in the compat RAND fork test.",
+ "configure": ["--enable-opensslextra", "CPPFLAGS=-DWOLFSSL_NO_GETPID"]},
+{"name": "rng-atfork-off-no-getpid", "minutes": 1.5,
+ "comment": "Neither the fork handlers nor the pid check: the compat RAND fork test must see the child repeat the parent.",
+ "configure": ["--disable-rng-atfork", "--enable-opensslextra", "CPPFLAGS=-DWOLFSSL_NO_GETPID"]},
 {"name": "no-verify-oid", "minutes": 1.1, "configure": ["CPPFLAGS=-DNO_VERIFY_OID"]},
+{"name": "rng-lock-off", "minutes": 1.1,
+ "comment": "Opt out of the per-instance RNG lock, so the WC_RNG layout and generate path without it are built and tested.",
+ "configure": ["--disable-rng-lock"]},
 {"name": "rng-seed-device", "minutes": 1.1,
  "comment": "Seed the RNG from a nominated device. /dev/urandom stands in for a hardware RNG so the WC_RNG_SEED_DEVICE read path is actually exercised on a runner.",
  "configure": ["--with-rng-seed-device=/dev/urandom"]},

.wolfssl_known_macro_extras

@@ -606,6 +606,8 @@ RNG_CR_CONDRST
 RNG_SR_BUSY
 RTC_ALARMSUBSECONDMASK_ALL
 RTE_CMSIS_RTOS_RTX
+RTLD_NODELETE
+RTLD_NOLOAD
 RTOS_MODULE_NET_AVAIL
 RTPLATFORM
 SAES
@@ -1289,6 +1291,7 @@ __MICROBLAZE__
 __MINGW32__
 __MINGW64_VERSION_MAJOR
 __MINGW64__
+__MSYS__
 __MWERKS__
 __NT__
 __OS2__

CMakeLists.txt

@@ -3765,6 +3765,16 @@ if(WOLFSSL_RNG_BANK)
     list(APPEND WOLFSSL_DEFINITIONS "-DWC_RNG_BANK_SUPPORT")
 endif()
 
+# RNG lock (share one WC_RNG between threads)
+add_option("WOLFSSL_RNG_LOCK"
+    "Enable the lock that lets one WC_RNG be shared between threads (default: enabled where the build supports it)"
+    "yes" "yes;no")
+# The lock defaults to yes, so a yes cannot be told from the default; the
+# header leaves it out where threads or the RNG are absent.
+if(NOT WOLFSSL_RNG_LOCK)
+    list(APPEND WOLFSSL_DEFINITIONS "-DWC_RNG_NO_LOCK")
+endif()
+
 # Valgrind (for unit tests)
 add_option("WOLFSSL_VALGRIND"
     "Enable valgrind for unit tests (default: disabled)"
@@ -3993,6 +4003,63 @@ if(NOT WOLFSSL_STATICMEMORY STREQUAL "no")
     endif()
 endif()
 
+# RNG fork handlers (a forked child keeps using its WC_RNG).  On by default;
+# a build that cannot carry them drops them.  Below the static memory option
+# because it reads it.
+add_option("WOLFSSL_RNG_ATFORK"
+    "Enable pthread_atfork handlers so a forked child can keep using a WC_RNG (default: enabled where supported)"
+    "yes" "yes;no")
+if(WOLFSSL_RNG_ATFORK)
+    set(RNG_ATFORK_NEEDS "")
+    if(WOLFSSL_USER_SETTINGS)
+        # CMake sets no defines in that mode; user_settings.h defines
+        # WC_RNG_ATFORK and WC_RNG_ATFORK_PIN itself
+        set(RNG_ATFORK_NEEDS "user_settings.h to define them")
+    elseif(WOLFSSL_SINGLE_THREADED OR WOLFSSL_LINUX_KM)
+        set(RNG_ATFORK_NEEDS "threads and no kernel module")
+    elseif(NOT WOLFSSL_RNG OR NOT WOLFSSL_RNG_LOCK OR NOT WOLFSSL_HASH_DRBG OR
+           WOLFSSL_RNG_BANK OR WOLFSSL_STATICMEMORY)
+        set(RNG_ATFORK_NEEDS "the RNG, its lock and the Hash DRBG, and no RNG bank or static memory")
+    else()
+        # real link tests: a toolchain whose try-compile only builds a static
+        # library reports every function as found
+        set(RNG_ATFORK_SAVED_LIBS "${CMAKE_REQUIRED_LIBRARIES}")
+        set(RNG_ATFORK_SAVED_TARGET "${CMAKE_TRY_COMPILE_TARGET_TYPE}")
+        set(CMAKE_TRY_COMPILE_TARGET_TYPE EXECUTABLE)
+        set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_THREAD_LIBS_INIT})
+        check_function_exists("pthread_atfork" HAVE_PTHREAD_ATFORK)
+        set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_DL_LIBS})
+        check_c_source_compiles("
+            #define _GNU_SOURCE 1
+            #include <stddef.h>
+            #include <stdint.h>
+            #include <dlfcn.h>
+            int main(void) {
+                Dl_info info;
+                const char* name;
+                if (dladdr((void*)(uintptr_t)main, &info) != 0) {
+                    name = info.dli_fname;
+                    if (name != NULL && name[0] != 0)
+                        (void)dlopen(name, RTLD_NOLOAD | RTLD_NODELETE | RTLD_LAZY);
+                }
+                return 0;
+            }" HAVE_DLADDR)
+        set(CMAKE_REQUIRED_LIBRARIES "${RNG_ATFORK_SAVED_LIBS}")
+        set(CMAKE_TRY_COMPILE_TARGET_TYPE "${RNG_ATFORK_SAVED_TARGET}")
+        if(NOT HAVE_PTHREAD_ATFORK)
+            set(RNG_ATFORK_NEEDS "pthread_atfork")
+        elseif(NOT HAVE_DLADDR)
+            set(RNG_ATFORK_NEEDS "dladdr and dlopen to pin the library against dlclose")
+        endif()
+    endif()
+    if(RNG_ATFORK_NEEDS)
+        message(STATUS "RNG fork handlers off: they need ${RNG_ATFORK_NEEDS}")
+    else()
+        list(APPEND WOLFSSL_DEFINITIONS "-DWC_RNG_ATFORK" "-DWC_RNG_ATFORK_PIN")
+        list(APPEND WOLFSSL_LINK_LIBS ${CMAKE_DL_LIBS})
+    endif()
+endif()
+
 # TLS (enabled by default; disable for wolfCrypt-only)
 add_option("WOLFSSL_TLS" "Enable TLS (default: enabled)" "yes" "yes;no")
 if(NOT WOLFSSL_TLS)

cmake/options.h.in

@@ -603,6 +603,12 @@ extern "C" {
 #cmakedefine FP_ECC
 #undef WC_RNG_BANK_SUPPORT
 #cmakedefine WC_RNG_BANK_SUPPORT
+#undef WC_RNG_NO_LOCK
+#cmakedefine WC_RNG_NO_LOCK
+#undef WC_RNG_ATFORK
+#cmakedefine WC_RNG_ATFORK
+#undef WC_RNG_ATFORK_PIN
+#cmakedefine WC_RNG_ATFORK_PIN
 #undef HAVE_VALGRIND
 #cmakedefine HAVE_VALGRIND
 #undef HAVE_CRL_MONITOR

configure.ac

@@ -2754,6 +2754,50 @@ then
 fi
 
 
+# RNG lock (share one WC_RNG between threads)
+AC_ARG_ENABLE([rng-lock],
+    [AS_HELP_STRING([--enable-rng-lock],[Enable the lock that lets one WC_RNG be shared between threads (default: enabled where the build supports it)])],
+    [ ENABLED_RNG_LOCK=$enableval ],
+    [ ENABLED_RNG_LOCK=yes ]
+    )
+
+case "$ENABLED_RNG_LOCK" in
+    yes|no) ;;
+    *) AC_MSG_ERROR([--enable-rng-lock takes yes or no]) ;;
+esac
+# raw enable_rng_lock: the option defaults to yes, so only an explicit ask
+# is an error here
+if test "x$enable_rng_lock" = "xyes" && test "$ENABLED_RNG" = "no"
+then
+    AC_MSG_ERROR([--enable-rng-lock requires --enable-rng])
+fi
+if test "$ENABLED_RNG_LOCK" = "no"
+then
+    AM_CFLAGS="$AM_CFLAGS -DWC_RNG_NO_LOCK"
+fi
+
+# RNG fork handlers (a forked child keeps using its WC_RNG); on wherever the
+# build supports them, decided in the late check with the other RNG checks
+AC_ARG_ENABLE([rng-atfork],
+    [AS_HELP_STRING([--enable-rng-atfork],[Enable pthread_atfork handlers so a forked child can keep using a WC_RNG (default: enabled where supported)])],
+    [ ENABLED_RNG_ATFORK=$enableval ],
+    [ ENABLED_RNG_ATFORK=yes ]
+    )
+
+case "$ENABLED_RNG_ATFORK" in
+    yes|no) ;;
+    *) AC_MSG_ERROR([--enable-rng-atfork takes yes or no]) ;;
+esac
+if test "$ENABLED_RNG" = "no" || test "$ENABLED_RNG_LOCK" = "no"
+then
+    if test "x$enable_rng_atfork" = "xyes"
+    then
+        AC_MSG_ERROR([--enable-rng-atfork requires --enable-rng and --enable-rng-lock])
+    fi
+    ENABLED_RNG_ATFORK=no
+fi
+
+
 # DTLS-SCTP
 AC_ARG_ENABLE([sctp],
     [AS_HELP_STRING([--enable-sctp],[Enable wolfSSL DTLS-SCTP support (default: disabled)])],
@@ -13248,6 +13292,108 @@ then
     AM_CFLAGS="$AM_CFLAGS -DHAVE___UINT128_T=1"
 fi
 
+# RNG lock and fork handlers need threads; the handlers need pthread_atfork
+# and everything the WC_RNG_LOCK_ATFORK gate in random.h asks for
+# (raw enable_rng_lock: only an explicit ask is an error, the default is yes)
+case "$AM_CFLAGS $CPPFLAGS $CFLAGS" in
+    *-DSINGLE_THREADED*) ENABLED_RNG_LOCK_THREADS=no ;;
+    *) ENABLED_RNG_LOCK_THREADS=yes ;;
+esac
+if test "$ENABLED_SINGLETHREADED" = "yes"
+then
+    ENABLED_RNG_LOCK_THREADS=no
+fi
+if test "x$enable_rng_lock" = "xyes" && test "$ENABLED_RNG_LOCK_THREADS" = "no"
+then
+    AC_MSG_ERROR([--enable-rng-lock requires threads])
+fi
+# The handlers default to on; a build that cannot carry them drops them
+# silently, unless they were asked for explicitly
+if test "$ENABLED_RNG_ATFORK" = "yes"
+then
+    RNG_ATFORK_NEEDS=""
+    if test "$ENABLED_USERSETTINGS" = "yes"
+    then
+        # user_settings.h owns every define in that mode
+        RNG_ATFORK_NEEDS="user_settings.h to define WC_RNG_ATFORK and WC_RNG_ATFORK_PIN"
+    fi
+    if test "$ENABLED_RNG_LOCK_THREADS" = "no" || \
+       test "$ENABLED_LINUXKM" = "yes" || test "$ENABLED_BSDKM" = "yes"
+    then
+        RNG_ATFORK_NEEDS="${RNG_ATFORK_NEEDS:+$RNG_ATFORK_NEEDS, and }threads and no kernel module"
+    fi
+    case "$AM_CFLAGS $CPPFLAGS $CFLAGS" in
+        *-DWOLFSSL_STATIC_MEMORY*|*-DWOLFSSL_NO_MALLOC*|*-DCUSTOM_RAND_GENERATE_BLOCK*)
+            ENABLED_RNG_ATFORK_HEAP=no ;;
+        *) ENABLED_RNG_ATFORK_HEAP=yes ;;
+    esac
+    case "$AM_CFLAGS $CPPFLAGS $CFLAGS" in
+        *-DWOLFSSL_CHECK_MEM_ZERO*) ENABLED_RNG_ATFORK_MEMZERO=yes ;;
+        *) ENABLED_RNG_ATFORK_MEMZERO=no ;;
+    esac
+    if test "$ENABLED_SELFTEST" = "yes" || test "x$ENABLED_HASHDRBG" != "xyes" || \
+       test "$ENABLED_ENTROPY_MEMUSE" != "no" || test "$ENABLED_RNG_BANK" = "yes" || \
+       test "$ENABLED_RNG_ATFORK_HEAP" = "no" || test "$ENABLED_WNR" = "yes" || \
+       test "$ENABLED_RNG_ATFORK_MEMZERO" = "yes" || \
+       { test "$ENABLED_FIPS" = "yes" && test "${HAVE_FIPS_VERSION_MAJOR:-0}" -lt 7; }
+    then
+        RNG_ATFORK_NEEDS="${RNG_ATFORK_NEEDS:+$RNG_ATFORK_NEEDS, and }the Hash DRBG with a heap and none of selftest, FIPS before v7, entropy-memuse, rng-bank, static memory, netRandom or memory zero checking"
+    fi
+    if test -z "$RNG_ATFORK_NEEDS"
+    then
+        saved_LIBS="$LIBS"
+        AC_SEARCH_LIBS([pthread_atfork], [pthread])
+        LIBS="$saved_LIBS"
+        if test "$ac_cv_search_pthread_atfork" = "no"
+        then
+            RNG_ATFORK_NEEDS="pthread_atfork"
+        fi
+    fi
+    if test -z "$RNG_ATFORK_NEEDS"
+    then
+        # the handlers can never be removed, so the image holding them is
+        # pinned with dladdr and dlopen; without them the handlers stay out.
+        # Compile and link the real thing: a bare symbol probe passes where
+        # the header hides dladdr or lacks the RTLD flags.
+        saved_LIBS="$LIBS"
+        AC_SEARCH_LIBS([dladdr], [dl])
+        AC_MSG_CHECKING([whether dladdr and dlopen can pin the library])
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+            #define _GNU_SOURCE 1
+            #include <stddef.h>
+            #include <stdint.h>
+            #include <dlfcn.h>
+            ]], [[
+            Dl_info info;
+            const char* name;
+            if (dladdr((void*)(uintptr_t)main, &info) != 0) {
+                name = info.dli_fname;
+                if (name != NULL && name[0] != '\0')
+                    (void)dlopen(name, RTLD_NOLOAD | RTLD_NODELETE | RTLD_LAZY);
+            }
+            ]])],
+            [AC_MSG_RESULT([yes])],
+            [AC_MSG_RESULT([no])
+             RNG_ATFORK_NEEDS="dladdr and dlopen to pin the library against dlclose"])
+        RNG_ATFORK_DL_LIBS="$LIBS"
+        LIBS="$saved_LIBS"
+    fi
+    if test -n "$RNG_ATFORK_NEEDS"
+    then
+        if test "x$enable_rng_atfork" = "xyes"
+        then
+            AC_MSG_ERROR([--enable-rng-atfork requires $RNG_ATFORK_NEEDS])
+        fi
+        AC_MSG_NOTICE([RNG fork handlers off: they need $RNG_ATFORK_NEEDS])
+        ENABLED_RNG_ATFORK=no
+    fi
+fi
+if test "$ENABLED_RNG_ATFORK" = "yes"
+then
+    AM_CFLAGS="$AM_CFLAGS -DWC_RNG_ATFORK -DWC_RNG_ATFORK_PIN"
+    LIBS="$RNG_ATFORK_DL_LIBS"   # -ldl where dladdr needed it, only with the pin
+fi
+
 # Add HAVE_GETPID to AM_CFLAGS for inclusion in options.h
 if test "$ac_cv_func_getpid" = "yes"
 then
@@ -14029,6 +14175,7 @@ echo "   * XCHACHA:                    $ENABLED_XCHACHA"
 echo "   * Hash DRBG:                  $ENABLED_HASHDRBG"
 echo "   * SHA-256 Hash DRBG:          $ENABLED_SHA256_DRBG"
 echo "   * SHA-512 Hash DRBG:          $ENABLED_SHA512_DRBG"
+echo "   * RNG fork handlers:          $ENABLED_RNG_ATFORK"
 echo "   * MmemUse Entropy:"
 echo "   * (AKA: wolfEntropy):         $ENABLED_ENTROPY_MEMUSE"
 echo "   * PWDBASED:                   $ENABLED_PWDBASED"