Imported linux-2.6.27.39 suse/xen patches.

[ipfire-2.x.git] / src / patches / suse-2.6.27.39 / patches.suse / self-ptrace.patch

From: Gerald Schaefer <geraldsc@de.ibm.com>
Subject: [PATCH] system call notification with self_ptrace
References: bnc#417299

PTRACE SELF

This patch adds a new functionality to ptrace: system call notification to
the current process.
When a process requests self ptrace, with the new request PTRACE_SELF_ON:

 1.  the next system call performed by the process will not be executed
 2.  self ptrace will be disabled for the process
 3.  a SIGSYS signal will be sent to the process.

With an appropriate SIGSYS signal handler, the process can access its own
data structures to

 1.  get the system call number from the siginfo structure
 2.  get the system call arguments from the stack
 3.  instrument the system call with other system calls
 4.  emulate the system call with other system calls
 5.  change the arguments of the system call
 6.  perform the system call for good
 7.  change the return value of the system call
 8.  request self ptrace again before returning.

The new request PTRACE_SELF_OFF disables self ptrace.


Signed-off-by: Pierre Morel <pmorel@fr.ibm.com>
Signed-off-by: Volker Sameske <sameske@de.ibm.com>

Acked-by: John Jolly <jjolly@suse.de>
---

 include/asm-generic/siginfo.h |    6 ++++++
 include/linux/ptrace.h        |   18 ++++++++++++++++++
 include/linux/sched.h         |    1 +
 kernel/ptrace.c               |   32 ++++++++++++++++++++++++++++++++
 4 files changed, 57 insertions(+)

--- a/include/asm-generic/siginfo.h
+++ b/include/asm-generic/siginfo.h
@@ -224,6 +224,12 @@ typedef struct siginfo {
 #define NSIGPOLL	6
 
 /*
+ * SIGSYS si_codes
+ */
+#define SYS_SYSCALL    (__SI_FAULT|1)  /* system call notification */
+#define NSIGSYS        1
+
+/*
  * sigevent definitions
  * 
  * It seems likely that SIGEV_THREAD will have to be handled from 
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -27,6 +27,10 @@
 #define PTRACE_GETSIGINFO	0x4202
 #define PTRACE_SETSIGINFO	0x4203
 
+/* PTRACE SELF requests					*/
+#define PTRACE_SELF_ON		0x4281
+#define PTRACE_SELF_OFF		0x4282
+
 /* options set using PTRACE_SETOPTIONS */
 #define PTRACE_O_TRACESYSGOOD	0x00000001
 #define PTRACE_O_TRACEFORK	0x00000002
@@ -78,7 +82,21 @@
 
 #include <linux/compiler.h>		/* For unlikely.  */
 #include <linux/sched.h>		/* For struct task_struct.  */
+#include <linux/unistd.h>		/* For syscall definitions  */
+
+#define PTS_INSTRUMENTED	0x00000001
+#define PTS_SELF	0x00000002
 
+static inline int is_self_ptracing(unsigned long syscall)
+{
+	if (!(current->instrumentation & PTS_SELF))
+		return 0;
+	if (syscall == __NR_rt_sigreturn)
+		return 0;
+	if (syscall == __NR_ptrace)
+		return 0;
+	return 1;
+}
 
 extern long arch_ptrace(struct task_struct *child, long request, long addr, long data);
 extern struct task_struct *ptrace_get_task_struct(pid_t pid);
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1308,6 +1308,7 @@ struct task_struct {
 	int latency_record_count;
 	struct latency_record latency_record[LT_SAVECOUNT];
 #endif
+	u64	instrumentation;
 };
 
 /*
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -554,6 +554,38 @@ SYSCALL_DEFINE4(ptrace, long, request, l
 	 * This lock_kernel fixes a subtle race with suid exec
 	 */
 	lock_kernel();
+	if (request == PTRACE_SELF_ON) {
+		task_lock(current);
+		if (current->ptrace) {
+			task_unlock(current);
+			ret = -EPERM;
+			goto out;
+		}
+		set_thread_flag(TIF_SYSCALL_TRACE);
+		current->instrumentation |= PTS_INSTRUMENTED|PTS_SELF;
+		task_unlock(current);
+		ret = 0;
+		goto out;
+	}
+	if (request == PTRACE_SELF_OFF) {
+		task_lock(current);
+		if (current->ptrace) {
+			task_unlock(current);
+			ret = -EPERM;
+			goto out;
+		}
+		clear_thread_flag(TIF_SYSCALL_TRACE);
+		current->instrumentation &= ~PTS_SELF;
+		task_unlock(current);
+		ret = 0;
+		goto out;
+	}
+
+	if (current->instrumentation) {
+		ret = -EPERM;
+		goto out;
+	}
+
 	if (request == PTRACE_TRACEME) {
 		ret = ptrace_traceme();
 		if (!ret)