From: Bodo Stroesser <bstroesser@fujitsu-siemens.com>

The patch syscall-security-3 is wrong (provided by me, sorry).
I missed, that singlestepping_skas() used to reset PT_DTRACE.
This was handled differently in tt and skas. With syscall-security-3
applied, a process in SKAS that singlestepped once continues to
singlestep until the next systemcall occurs, even if it is resumed
with PTRACE_CONT or PTRACE_SYSCALL.
This fix unifies the usage of PT_DTRACE in TT and SKAS. PT_DTRACE now
is set by ptrace(PTRACE_SINGLESTEP,...) and reset by singlestepping()
and it is evaluated in kern_do_signal().


Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
---


--- linux-2.6.9-rc2/arch/um/kernel/process_kern.c	2004-10-01 18:42:27.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/process_kern.c	2004-10-05 21:09:48.303849436 +0200
@@ -405,9 +405,15 @@
 {
 	struct task_struct *task = t ? t : current;
 
+	if ( ! (task->ptrace & PT_DTRACE) )
+		return(0);
+
+	task->ptrace &= ~PT_DTRACE;
+
 	if (task->thread.singlestep_syscall)
 		return(0);
-	return(task->ptrace & PT_DTRACE);
+
+	return 1;
 }
 
 /*
--- linux-2.6.9-rc2/arch/um/kernel/skas/syscall_kern.c	2004-10-01 18:28:35.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/skas/syscall_kern.c	2004-10-05 21:11:04.609239526 +0200
@@ -30,7 +30,6 @@
 
 	if(current->thread.singlestep_syscall){
 		current->thread.singlestep_syscall = 0;
-		current->ptrace &= ~PT_DTRACE;
 		force_sig(SIGTRAP, current);
 	}
 
--- linux-2.6.9-rc2/arch/um/kernel/tt/syscall_kern.c	2004-10-01 18:01:35.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/tt/syscall_kern.c	2004-10-05 21:11:30.088029008 +0200
@@ -32,7 +32,6 @@
 
 	if(current->thread.singlestep_syscall){
 		current->thread.singlestep_syscall = 0;
-		current->ptrace &= ~PT_DTRACE;
 		force_sig(SIGTRAP, current);
 	}
 
--- linux-2.6.9-rc2/arch/um/kernel/tt/process_kern.c	2004-10-01 18:36:17.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/tt/process_kern.c	2004-10-05 21:12:15.933452785 +0200
@@ -524,13 +524,6 @@
 		      -err);
 }
 
-void clear_singlestep(void *t)
-{
-	struct task_struct *task = t;
-
-	task->ptrace &= ~PT_DTRACE;
-}
-
 int start_uml_tt(void)
 {
 	void *sp;
--- linux-2.6.9-rc2/arch/um/kernel/tt/tracer.c	2004-10-01 18:33:30.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/tt/tracer.c	2004-10-05 21:13:12.106169916 +0200
@@ -331,7 +331,6 @@
 				tracing = 0;
 				if(do_syscall(task, pid))
 					sig = SIGUSR2;
-				else clear_singlestep(task);
 				break;
 			case SIGPROF:
 				if(tracing) sig = 0;
--- linux-2.6.9-rc2/arch/um/kernel/tt/include/tt.h	2004-10-01 18:34:01.000000000 +0200
+++ linux-2.6.9-rc2-orig/arch/um/kernel/tt/include/tt.h	2004-10-05 21:13:36.778092737 +0200
@@ -24,7 +24,6 @@
 extern int set_user_mode(void *task);
 extern void set_tracing(void *t, int tracing);
 extern int is_tracing(void *task);
-extern void clear_singlestep(void *t);
 extern void syscall_handler(int sig, union uml_pt_regs *regs);
 extern void exit_kernel(int pid, void *task);
 extern int do_syscall(void *task, int pid);