Detach after exec() if we don't have permission to debug the child (i…

…t's setuid/setgid).

2009-10-19  Martin Baulig  <martin@ximian.com>

	Detach after exec() if we don't have permission to debug the
	child; this happens if the exec()d binary is setuid/setgid.

	* backend/Inferior.cs
	(Inferior.ProcessEvent): Removed child_execd().
	(Inferior.InitializeAfterExec): Call GetApplication() and
	start.SetupApplication() here.

	* backend/ProcessServant.cs
	(ProcessServant.ChildExecd): Catch `TargetError.PermissionDenied'
	and detach from the process; this happens when exec()ing
	setuid/setgid applications.

	* classes/TargetException.cs
	(TargetError): Add `PermissionDenied'.

	* backend/server/x86-linux-ptrace.c
	(_server_ptrace_setup_inferior): Check `EACCES' and return
	`COMMAND_ERROR_PERMISSION_DENIED'.

svn path=/trunk/debugger/; revision=144386

ChangeLog

@@ -1,3 +1,25 @@
+2009-10-19  Martin Baulig  <martin@ximian.com>
+
+	Detach after exec() if we don't have permission to debug the
+	child; this happens if the exec()d binary is setuid/setgid.
+
+	* backend/Inferior.cs
+	(Inferior.ProcessEvent): Removed child_execd().
+	(Inferior.InitializeAfterExec): Call GetApplication() and
+	start.SetupApplication() here.
+
+	* backend/ProcessServant.cs
+	(ProcessServant.ChildExecd): Catch `TargetError.PermissionDenied'
+	and detach from the process; this happens when exec()ing
+	setuid/setgid applications.
+
+	* classes/TargetException.cs
+	(TargetError): Add `PermissionDenied'.
+
+	* backend/server/x86-linux-ptrace.c
+	(_server_ptrace_setup_inferior): Check `EACCES' and return
+	`COMMAND_ERROR_PERMISSION_DENIED'.
+
 2009-10-14  Martin Baulig  <martin@ximian.com>
 
 	* backend/SingleSteppingEngine.cs

backend/Inferior.cs

@@ -698,6 +698,12 @@ public void InitializeAfterExec (int pid)
 			check_error (mono_debugger_server_initialize_thread (server_handle, pid, false));
 			this.child_pid = pid;
 
+			string exe_file, cwd;
+			string[] cmdline_args;
+			exe_file = GetApplication (out cwd, out cmdline_args);
+
+			start.SetupApplication (exe_file, cwd, cmdline_args);
+
 			SetupInferior ();
 
 			change_target_state (TargetState.Stopped, 0);
@@ -726,17 +732,6 @@ public void Attach (int pid)
 			change_target_state (TargetState.Stopped, 0);
 		}
 
-		void child_execd ()
-		{
-			string exe_file, cwd;
-			string[] cmdline_args;
-			exe_file = GetApplication (out cwd, out cmdline_args);
-
-			start.SetupApplication (exe_file, cwd, cmdline_args);
-
-			SetupInferior ();
-		}
-
 		public ChildEvent ProcessEvent (int status)
 		{
 			long arg, data1, data2;
@@ -766,7 +761,6 @@ public ChildEvent ProcessEvent (int status)
 				break;
 
 			case ChildEventType.CHILD_EXECD:
-				child_execd ();
 				break;
 			}
 
@@ -1376,7 +1370,7 @@ protected string GetApplication (out string cwd, out string[] cmdline_args)
 				int count;
 				string exe_file;
 				check_error (mono_debugger_server_get_application (
-							 server_handle, out p_exe, out p_cwd,
+						     server_handle, out p_exe, out p_cwd,
 						     out count, out data));
 
 				cmdline_args = new string [count];

backend/ProcessServant.cs

@@ -281,7 +281,18 @@ internal void ChildExecd (SingleSteppingEngine engine, Inferior inferior)
 			native_language = new NativeLanguage (this, os, target_info);
 
 			Inferior new_inferior = Inferior.CreateInferior (manager, this, start);
-			new_inferior.InitializeAfterExec (inferior.PID);
+			try {
+				new_inferior.InitializeAfterExec (inferior.PID);
+			} catch (Exception ex) {
+				if ((ex is TargetException) && (((TargetException) ex).Type == TargetError.PermissionDenied)) {
+					Report.Error ("Permission denied when trying to debug exec()ed child {0}, detaching!",
+						      inferior.PID);
+				} else {
+					Report.Error ("InitializeAfterExec() failed on pid {0}: {1}", inferior.PID, ex);
+				}
+				new_inferior.DetachAfterFork ();
+				return;
+			}
 
 			SingleSteppingEngine new_thread = new SingleSteppingEngine (
 				manager, this, new_inferior, inferior.PID);

backend/server/server.h

@@ -36,6 +36,7 @@ typedef enum {
 	COMMAND_ERROR_NOT_IMPLEMENTED,
 	COMMAND_ERROR_IO_ERROR,
 	COMMAND_ERROR_NO_CALLBACK_FRAME,
+	COMMAND_ERROR_PERMISSION_DENIED
 } ServerCommandError;
 
 typedef enum {

backend/server/x86-linux-ptrace.c

@@ -491,6 +491,9 @@ _server_ptrace_setup_inferior (ServerHandle *handle)
 	handle->inferior->os.mem_fd = open64 (filename, O_RDONLY);
 
 	if (handle->inferior->os.mem_fd < 0) {
+		if (errno == EACCES)
+			return COMMAND_ERROR_PERMISSION_DENIED;
+
 		g_warning (G_STRLOC ": Can't open (%s): %s", filename, g_strerror (errno));
 		return COMMAND_ERROR_UNKNOWN_ERROR;
 	}
@@ -614,15 +617,20 @@ server_ptrace_get_application (ServerHandle *handle, gchar **exe_file, gchar **c
 	char buffer [BUFSIZ+1];
 	GPtrArray *array;
 	gchar *cmdline, **ptr;
-	gsize pos, len;
+	gssize pos, len;
 	int i;
 
 	len = readlink (exe_filename, buffer, BUFSIZ);
 	if (len < 0) {
 		g_free (cwd_filename);
 		g_free (exe_filename);
 		g_free (cmdline_filename);
-		g_warning (G_STRLOC ": Can't get exe file of %d", handle->inferior->pid);
+
+		if (errno == EACCES)
+			return COMMAND_ERROR_PERMISSION_DENIED;
+
+		g_warning (G_STRLOC ": Can't get exe file of %d: %s", handle->inferior->pid,
+			   g_strerror (errno));
 		return COMMAND_ERROR_UNKNOWN_ERROR;
 	}
 
@@ -634,7 +642,8 @@ server_ptrace_get_application (ServerHandle *handle, gchar **exe_file, gchar **c
 		g_free (cwd_filename);
 		g_free (exe_filename);
 		g_free (cmdline_filename);
-		g_warning (G_STRLOC ": Can't get cwd of %d", handle->inferior->pid);
+		g_warning (G_STRLOC ": Can't get cwd of %d: %s", handle->inferior->pid,
+			   g_strerror (errno));
 		return COMMAND_ERROR_UNKNOWN_ERROR;
 	}
 

classes/TargetException.cs

@@ -23,6 +23,7 @@ public enum TargetError {
 		NotImplemented,
 		IOError,
 		NoCallbackFrame,
+		PermissionDenied,
 
 		NoStack			= 101,
 		NoMethod,
@@ -115,6 +116,8 @@ protected static string GetMessage (TargetError type)
 				return "No invocation found.";
 			case TargetError.InvalidContext:
 				return "Operation not permitted outside managed context.";
+			case TargetError.PermissionDenied:
+				return "Permission denied.";
 			default:
 				return "Unknown error";
 			}