[release/6.0][EventPipe] Fix reverse connection socket leaking to child processes. (#65768)

* [release/6.0][EventPipe] Fix reverse connection socket leaking to child processes.

Sockets were getting leaked upon accepting connections. This meant that child processes could cause
fully terminated tracing sessions and other IPC connections alive, causing clients to wait for input
indefinitely. This sets the CLOEXEC bits on the socket atomically upon accepting if the OS provides
the capability, falling back to a best effort fcntl on systems like macOS and x866 Android emulators.

Port of dotnet/runtime#65365 to release/6.0.

* Include well know cmake paths

8 files changed, 50 insertions, 4 deletions

diff --git a/src/coreclr/CMakeLists.txt b/src/coreclr/CMakeLists.txt
index 13885a61635..4aaad5724ce 100644
--- a/src/coreclr/CMakeLists.txt
+++ b/src/coreclr/CMakeLists.txt
@@ -124,6 +124,9 @@ endif(CLR_CMAKE_HOST_UNIX)
 # Add this subdir. We install the headers for the jit.
 add_subdirectory(pal/prebuilt/inc)
 
+# These need to happen before the VM and debug-pal includes.
+set(EP_GENERATED_HEADER_PATH "${GENERATED_INCLUDE_DIR}")
+include(${CLR_SRC_NATIVE_DIR}/eventpipe/configure.cmake)
 add_subdirectory(debug/debug-pal)
 
 add_subdirectory(minipal)
diff --git a/src/coreclr/debug/debug-pal/CMakeLists.txt b/src/coreclr/debug/debug-pal/CMakeLists.txt
index d2846f93b13..a382af2c07a 100644
--- a/src/coreclr/debug/debug-pal/CMakeLists.txt
+++ b/src/coreclr/debug/debug-pal/CMakeLists.txt
@@ -1,6 +1,6 @@
-
 include_directories(../inc)
 include_directories(../../pal/inc)
+include_directories(${EP_GENERATED_HEADER_PATH})
 
 add_definitions(-DPAL_STDCPP_COMPAT)
 
diff --git a/src/coreclr/vm/eventing/eventpipe/CMakeLists.txt b/src/coreclr/vm/eventing/eventpipe/CMakeLists.txt
index 3b03605aece..0936de2998e 100644
--- a/src/coreclr/vm/eventing/eventpipe/CMakeLists.txt
+++ b/src/coreclr/vm/eventing/eventpipe/CMakeLists.txt
@@ -92,6 +92,7 @@ list(APPEND EVENTPIPE_SOURCES
   ${CORECLR_EVENTPIPE_SHIM_SOURCES}
   ${CORECLR_EVENTPIPE_SHIM_HEADERS}
   ${EVENTPIPE_HEADERS}
+  ${SHARED_EVENTPIPE_CONFIG_HEADERS}
 )
 
 add_library_clr(eventpipe_gen_objs OBJECT ${GEN_EVENTPIPE_SOURCES})
diff --git a/src/mono/mono/eventpipe/CMakeLists.txt b/src/mono/mono/eventpipe/CMakeLists.txt
index 530abd59086..ccc55d57300 100644
--- a/src/mono/mono/eventpipe/CMakeLists.txt
+++ b/src/mono/mono/eventpipe/CMakeLists.txt
@@ -1,3 +1,8 @@
+# For feature detection to work correctly, this needs to be outside of the conditional.
+set(EP_GENERATED_HEADER_PATH "${MONO_EVENTPIPE_GEN_INCLUDE_PATH}")
+include(../../../../eng/native/configurepaths.cmake)
+include(${SHARED_EVENTPIPE_SOURCE_PATH}configure.cmake)
+
 if(ENABLE_PERFTRACING)
 
     include(${MONO_EVENTPIPE_SHIM_SOURCE_PATH}/gen-eventing.cmake)
@@ -79,7 +84,7 @@ if(ENABLE_PERFTRACING)
     addprefix(shared_diagnostic_server_sources_base ${SHARED_EVENTPIPE_SOURCE_PATH} "${shared_diagnostic_server_sources_base}")
     addprefix(mono_diagnostic_server_shim_sources_base ${MONO_EVENTPIPE_SHIM_SOURCE_PATH} "${mono_diagnostic_server_shim_sources_base}")
 
-    set(eventpipe_sources ${shared_eventpipe_sources_base} ${mono_eventpipe_shim_sources_base} ${MONO_EVENTPIPE_GEN_HEADERS} ${MONO_EVENTPIPE_GEN_SOURCES})
+    set(eventpipe_sources ${shared_eventpipe_sources_base} ${SHARED_EVENTPIPE_CONFIG_HEADERS} ${mono_eventpipe_shim_sources_base} ${MONO_EVENTPIPE_GEN_HEADERS} ${MONO_EVENTPIPE_GEN_SOURCES})
     set(diagnostic_server_sources ${shared_diagnostic_server_sources_base} ${mono_diagnostic_server_shim_sources_base})
 
     set_source_files_properties(${SHARED_EVENTPIPE_SOURCE_PATH}/ep-sources.c PROPERTIES COMPILE_DEFINITIONS EP_FORCE_INCLUDE_SOURCE_FILES)
diff --git a/src/native/eventpipe/configure.cmake b/src/native/eventpipe/configure.cmake
new file mode 100644
index 00000000000..15716ed8d97
--- /dev/null
+++ b/src/native/eventpipe/configure.cmake
@@ -0,0 +1,14 @@
+include(CheckSymbolExists)
+
+check_symbol_exists(
+    accept4
+    sys/socket.h
+    HAVE_ACCEPT4)
+
+if (NOT DEFINED EP_GENERATED_HEADER_PATH)
+    message(FATAL_ERROR "Required configuration EP_GENERATED_HEADER_PATH not set.")
+endif (NOT DEFINED EP_GENERATED_HEADER_PATH)
+
+configure_file(${CLR_SRC_NATIVE_DIR}/eventpipe/ep-shared-config.h.in ${EP_GENERATED_HEADER_PATH}/ep-shared-config.h)
+
+set (SHARED_EVENTPIPE_CONFIG_HEADERS "${EP_GENERATED_HEADER_PATH}/ep-shared-config.h")
diff --git a/src/native/eventpipe/ds-ipc-pal-socket.c b/src/native/eventpipe/ds-ipc-pal-socket.c
index 2f7cb928706..04b06451eff 100644
--- a/src/native/eventpipe/ds-ipc-pal-socket.c
+++ b/src/native/eventpipe/ds-ipc-pal-socket.c
@@ -530,8 +530,22 @@ ipc_socket_accept (
 	ds_ipc_socket_t client_socket;
 	DS_ENTER_BLOCKING_PAL_SECTION;
 	do {
-		client_socket = accept (s, address, address_len);
+#if defined(HAVE_ACCEPT4) && defined(SOCK_CLOEXEC)
+    	client_socket = accept4 (s, address, address_len, SOCK_CLOEXEC);
+#else
+    	client_socket = accept (s, address, address_len);
+#endif
 	} while (ipc_retry_syscall (client_socket));
+
+#if !defined(HAVE_ACCEPT4) || !defined(SOCK_CLOEXEC)
+#if defined(FD_CLOEXEC)
+    if (client_socket != -1)
+    {
+        // ignore any failures; this is best effort
+        fcntl (client_socket, F_SETFD, FD_CLOEXEC);
+    }
+#endif
+#endif
 	DS_EXIT_BLOCKING_PAL_SECTION;
 	return client_socket;
 }
@@ -834,7 +848,7 @@ ipc_alloc_tcp_address (
 
 	const ep_char8_t *host_address = address;
 	const ep_char8_t *host_port = strrchr (address, ':');
-	
+
 	if (host_port && host_port != host_address) {
 		size_t host_address_len = host_port - address;
 		address [host_address_len] = 0;
diff --git a/src/native/eventpipe/ep-rt-config.h b/src/native/eventpipe/ep-rt-config.h
index 94efb3ebdd6..4d5a6cc98c1 100644
--- a/src/native/eventpipe/ep-rt-config.h
+++ b/src/native/eventpipe/ep-rt-config.h
@@ -1,6 +1,8 @@
 #ifndef __EVENTPIPE_RT_CONFIG_H__
 #define __EVENTPIPE_RT_CONFIG_H__
 
+#include "ep-shared-config.h"
+
 #ifndef FEATURE_CORECLR
 
 #include <config.h>
diff --git a/src/native/eventpipe/ep-shared-config.h.in b/src/native/eventpipe/ep-shared-config.h.in
new file mode 100644
index 00000000000..18e1f7f78f8
--- /dev/null
+++ b/src/native/eventpipe/ep-shared-config.h.in
@@ -0,0 +1,7 @@
+#ifndef EP_SHARED_CONFIG_H_INCLUDED
+#define EP_SHARED_CONFIG_H_INCLUDED
+
+/* This platforms supports setting flags atomically when accepting connections. */
+#cmakedefine01 HAVE_ACCEPT4
+
+#endif //EP_SHARED_CONFIG_H_INCLUDED