commit b049cc3ace18dd42493ca768cf4636dfd89569fc Author: David Goulet dgoulet@torproject.org Date: Wed Mar 11 12:12:28 2020 -0400

trace: Emit a warning if tracing is built in

Built in tracing should _not_ be run if it was not set on purpose. Warn as loud as we can in order to inform the user that they are running a version with tracing capabilities built in.

This commit also adds a subsys stub because utlimately the logging will happen in the init phase but because the default log file is not set in the sys_logging init function, the stub is not useful for now.

Signed-off-by: David Goulet dgoulet@torproject.org --- configure.ac | 7 ++++++- src/app/main/main.c | 4 ++++ src/lib/trace/include.am | 4 ++++ src/lib/trace/trace.h | 21 +++++++++++++++++++++ src/lib/trace/trace_stub.c | 19 +++++++++++++++++++ src/lib/trace/trace_sys.c | 5 ++++- src/lib/trace/trace_sys.h | 8 ++++++++ 7 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac index cd014268b..75fd709f9 100644 --- a/configure.ac +++ b/configure.ac @@ -273,9 +273,9 @@ if test "x$enable_tracing_instrumentation_lttng" = "xyes"; then On Debian, apt install liblttng-ust-dev"])], []) AC_DEFINE([USE_TRACING_INSTRUMENTATION_LTTNG], [1], [Using LTTng instrumentation]) TOR_TRACE_LIBS="-llttng-ust -ldl" + have_tracing=1 fi

- dnl USDT instrumentation option. AC_ARG_ENABLE(tracing-instrumentation-usdt, AS_HELP_STRING([--enable-tracing-instrumentation-usdt], @@ -291,6 +291,7 @@ if test "x$enable_tracing_instrumentation_usdt" = "xyes"; then dnl --with-sdt. There is unfortunately no way to check that so we always dnl build the USDT probes even though LTTng instrumentation was requested. AC_DEFINE([USE_TRACING_INSTRUMENTATION_USDT], [1], [Using USDT instrumentation]) + have_tracing=1 fi

dnl Tracepoints event to debug logs. @@ -301,6 +302,9 @@ AC_ARG_ENABLE(tracing-instrumentation-log-debug, [Tracepoints to log debug]), []) AM_CONDITIONAL([USE_TRACING_INSTRUMENTATION_LOG_DEBUG], [test "x$enable_tracing_instrumentation_log_debug" = "xyes"]) +if test "x$enable_tracing_instrumentation_log_debug" = "xyes"; then + have_tracing=1 +fi

dnl Define that tracing is supported if any instrumentation is used. AM_COND_IF([USE_TRACING_INSTRUMENTATION_LOG_DEBUG], @@ -309,6 +313,7 @@ AM_COND_IF([USE_TRACING_INSTRUMENTATION_USDT], AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support])) AM_COND_IF([USE_TRACING_INSTRUMENTATION_LTTNG], AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support])) +AM_CONDITIONAL([USE_TRACING], [test "x$have_tracing" = x1 ])

dnl Finally, define the trace libs. AC_SUBST([TOR_TRACE_LIBS]) diff --git a/src/app/main/main.c b/src/app/main/main.c index 89ba78742..e1d5772e3 100644 --- a/src/app/main/main.c +++ b/src/app/main/main.c @@ -59,6 +59,7 @@ #include "lib/crypt_ops/crypto_rand.h" #include "lib/crypt_ops/crypto_s2k.h" #include "lib/net/resolve.h" +#include "lib/trace/trace.h"

#include "lib/process/waitpid.h" #include "lib/pubsub/pubsub_build.h" @@ -602,6 +603,9 @@ tor_init(int argc, char *argv[]) rust_log_welcome_string(); #endif /* defined(HAVE_RUST) */

+ /* Warn _if_ the tracing subsystem is built in. */ + tracing_log_warning(); + int init_rv = options_init_from_torrc(argc,argv); if (init_rv < 0) { log_err(LD_CONFIG,"Reading config failed--see warnings above."); diff --git a/src/lib/trace/include.am b/src/lib/trace/include.am index 844033132..6fe136565 100644 --- a/src/lib/trace/include.am +++ b/src/lib/trace/include.am @@ -26,6 +26,10 @@ if USE_TRACING_INSTRUMENTATION_LTTNG include src/lib/trace/lttng/include.am endif

+if USE_TRACING src_lib_libtor_trace_a_SOURCES = $(LIBTOR_TRACE_A_SOURCES) +else +src_lib_libtor_trace_a_SOURCES = src/lib/trace/trace_stub.c +endif

noinst_HEADERS+= $(TRACEHEADERS) diff --git a/src/lib/trace/trace.h b/src/lib/trace/trace.h index 94cbbc1e4..22589dbe9 100644 --- a/src/lib/trace/trace.h +++ b/src/lib/trace/trace.h @@ -9,7 +9,28 @@ #ifndef TOR_LIB_TRACE_TRACE_H #define TOR_LIB_TRACE_TRACE_H

+#include "orconfig.h" + void tor_trace_init(void); void tor_trace_free_all(void);

+#ifdef HAVE_TRACING + +#include "lib/log/log.h" + +static inline void +tracing_log_warning(void) +{ + log_warn(LD_GENERAL, + "Tracing capabilities have been built in. If this is NOT on " + "purpose, your tor is NOT safe to run."); +} + +#else + +/* NOP it. */ +#define tracing_log_warning() + +#endif /* defined(HAVE_TRACING) */ + #endif /* !defined(TOR_LIB_TRACE_TRACE_H) */ diff --git a/src/lib/trace/trace_stub.c b/src/lib/trace/trace_stub.c new file mode 100644 index 000000000..9043efe36 --- /dev/null +++ b/src/lib/trace/trace_stub.c @@ -0,0 +1,19 @@ +/* Copyright (c) 2020, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file trace_stub.c + * \brief Stub declaratinos for use when trace library is disabled. + **/ + +#include "lib/subsys/subsys.h" + +#include "lib/trace/trace_sys.h" + +const subsys_fns_t sys_tracing = { + SUBSYS_DECLARE_LOCATION(), + + .name = "tracing", + .supported = false, + .level = TRACE_SUBSYS_LEVEL, +}; diff --git a/src/lib/trace/trace_sys.c b/src/lib/trace/trace_sys.c index d6e59f4c3..2ba025840 100644 --- a/src/lib/trace/trace_sys.c +++ b/src/lib/trace/trace_sys.c @@ -25,9 +25,12 @@ subsys_tracing_shutdown(void) }

const subsys_fns_t sys_tracing = { + SUBSYS_DECLARE_LOCATION(), + .name = "tracing", .supported = true, - .level = -85, + .level = TRACE_SUBSYS_LEVEL, + .initialize = subsys_tracing_initialize, .shutdown = subsys_tracing_shutdown, }; diff --git a/src/lib/trace/trace_sys.h b/src/lib/trace/trace_sys.h index e9c97c08f..d4da5a970 100644 --- a/src/lib/trace/trace_sys.h +++ b/src/lib/trace/trace_sys.h @@ -11,4 +11,12 @@

extern const struct subsys_fns_t sys_tracing;

+/** + * Subsystem level for the tracing system. + * + * Defined here so that it can be shared between the real and stub + * definitions. + **/ +#define TRACE_SUBSYS_LEVEL (-85) + #endif /* !defined(TOR_TRACE_SYS_H) */