sh: convert /proc/cpu/aligmnent, /proc/cpu/kernel_alignment to seq_file
[safe/jmp/linux-2.6] / kernel / ptrace.c
index 5b8dd98..23bd09c 100644 (file)
@@ -7,6 +7,7 @@
  * to continually duplicate across every architecture.
  */
 
+#include <linux/capability.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
 #include <linux/security.h>
 #include <linux/signal.h>
+#include <linux/audit.h>
+#include <linux/pid_namespace.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
 
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
 
 /*
  * ptrace a task: make the debugger its new parent and
  *
  * Must be called with the tasklist lock write-held.
  */
-void __ptrace_link(task_t *child, task_t *new_parent)
+void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-       if (!list_empty(&child->ptrace_list))
-               BUG();
-       if (child->parent == new_parent)
-               return;
-       list_add(&child->ptrace_list, &child->parent->ptrace_children);
-       REMOVE_LINKS(child);
+       BUG_ON(!list_empty(&child->ptrace_entry));
+       list_add(&child->ptrace_entry, &new_parent->ptraced);
        child->parent = new_parent;
-       SET_LINKS(child);
 }
+
 /*
  * Turn a tracing stop into a normal stop now, since with no tracer there
  * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
@@ -46,19 +44,19 @@ void __ptrace_link(task_t *child, task_t *new_parent)
  * TASK_TRACED, resume it now.
  * Requires that irqs be disabled.
  */
-void ptrace_untrace(task_t *child)
+static void ptrace_untrace(struct task_struct *child)
 {
        spin_lock(&child->sighand->siglock);
-       if (child->state == TASK_TRACED) {
-               if (child->signal->flags & SIGNAL_STOP_STOPPED) {
-                       child->state = TASK_STOPPED;
-               } else {
+       if (task_is_traced(child)) {
+               /*
+                * If the group stop is completed or in progress,
+                * this thread was already counted as stopped.
+                */
+               if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+                   child->signal->group_stop_count)
+                       __set_task_state(child, TASK_STOPPED);
+               else
                        signal_wake_up(child, 1);
-               }
-       }
-       if (child->signal->flags & SIGNAL_GROUP_EXIT) {
-               sigaddset(&child->pending.signal, SIGKILL);
-               signal_wake_up(child, 1);
        }
        spin_unlock(&child->sighand->siglock);
 }
@@ -69,19 +67,17 @@ void ptrace_untrace(task_t *child)
  *
  * Must be called with the tasklist lock write-held.
  */
-void __ptrace_unlink(task_t *child)
+void __ptrace_unlink(struct task_struct *child)
 {
-       if (!child->ptrace)
-               BUG();
+       BUG_ON(!child->ptrace);
+
        child->ptrace = 0;
-       if (!list_empty(&child->ptrace_list)) {
-               list_del_init(&child->ptrace_list);
-               REMOVE_LINKS(child);
-               child->parent = child->real_parent;
-               SET_LINKS(child);
-       }
+       child->parent = child->real_parent;
+       list_del_init(&child->ptrace_entry);
 
-       ptrace_untrace(child);
+       arch_ptrace_untrace(child);
+       if (task_is_traced(child))
+               ptrace_untrace(child);
 }
 
 /*
@@ -99,51 +95,71 @@ int ptrace_check_attach(struct task_struct *child, int kill)
         * be changed by us so it's not changing right after this.
         */
        read_lock(&tasklist_lock);
-       if ((child->ptrace & PT_PTRACED) && child->parent == current &&
-           (!(child->ptrace & PT_ATTACHED) || child->real_parent != current)
-           && child->signal != NULL) {
+       if ((child->ptrace & PT_PTRACED) && child->parent == current) {
                ret = 0;
+               /*
+                * child->sighand can't be NULL, release_task()
+                * does ptrace_unlink() before __exit_signal().
+                */
                spin_lock_irq(&child->sighand->siglock);
-               if (child->state == TASK_STOPPED) {
+               if (task_is_stopped(child))
                        child->state = TASK_TRACED;
-               } else if (child->state != TASK_TRACED && !kill) {
+               else if (!task_is_traced(child) && !kill)
                        ret = -ESRCH;
-               }
                spin_unlock_irq(&child->sighand->siglock);
        }
        read_unlock(&tasklist_lock);
 
-       if (!ret && !kill) {
-               wait_task_inactive(child);
-       }
+       if (!ret && !kill)
+               ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 
        /* All systems go.. */
        return ret;
 }
 
-static int may_attach(struct task_struct *task)
+int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
-       if (!task->mm)
-               return -EPERM;
-       if (((current->uid != task->euid) ||
-            (current->uid != task->suid) ||
-            (current->uid != task->uid) ||
-            (current->gid != task->egid) ||
-            (current->gid != task->sgid) ||
-            (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
+       const struct cred *cred = current_cred(), *tcred;
+
+       /* May we inspect the given task?
+        * This check is used both for attaching with ptrace
+        * and for allowing access to sensitive information in /proc.
+        *
+        * ptrace_attach denies several cases that /proc allows
+        * because setting up the necessary parent/child relationship
+        * or halting the specified task is impossible.
+        */
+       int dumpable = 0;
+       /* Don't let security modules deny introspection */
+       if (task == current)
+               return 0;
+       rcu_read_lock();
+       tcred = __task_cred(task);
+       if ((cred->uid != tcred->euid ||
+            cred->uid != tcred->suid ||
+            cred->uid != tcred->uid  ||
+            cred->gid != tcred->egid ||
+            cred->gid != tcred->sgid ||
+            cred->gid != tcred->gid) &&
+           !capable(CAP_SYS_PTRACE)) {
+               rcu_read_unlock();
                return -EPERM;
+       }
+       rcu_read_unlock();
        smp_rmb();
-       if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+       if (task->mm)
+               dumpable = get_dumpable(task->mm);
+       if (!dumpable && !capable(CAP_SYS_PTRACE))
                return -EPERM;
 
-       return security_ptrace(current, task);
+       return security_ptrace_access_check(task, mode);
 }
 
-int ptrace_may_attach(struct task_struct *task)
+bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
        int err;
        task_lock(task);
-       err = may_attach(task);
+       err = __ptrace_may_access(task, mode);
        task_unlock(task);
        return !err;
 }
@@ -151,111 +167,184 @@ int ptrace_may_attach(struct task_struct *task)
 int ptrace_attach(struct task_struct *task)
 {
        int retval;
-       task_lock(task);
+
+       audit_ptrace(task);
+
        retval = -EPERM;
-       if (task->pid <= 1)
-               goto bad;
-       if (task == current)
-               goto bad;
-       /* the same process cannot be attached many times */
-       if (task->ptrace & PT_PTRACED)
-               goto bad;
-       retval = may_attach(task);
+       if (unlikely(task->flags & PF_KTHREAD))
+               goto out;
+       if (same_thread_group(task, current))
+               goto out;
+
+       /*
+        * Protect exec's credential calculations against our interference;
+        * interference; SUID, SGID and LSM creds get determined differently
+        * under ptrace.
+        */
+       retval = -ERESTARTNOINTR;
+       if (mutex_lock_interruptible(&task->cred_guard_mutex))
+               goto out;
+
+       task_lock(task);
+       retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
+       task_unlock(task);
        if (retval)
-               goto bad;
+               goto unlock_creds;
+
+       write_lock_irq(&tasklist_lock);
+       retval = -EPERM;
+       if (unlikely(task->exit_state))
+               goto unlock_tasklist;
+       if (task->ptrace)
+               goto unlock_tasklist;
 
-       /* Go */
-       task->ptrace |= PT_PTRACED | ((task->real_parent != current)
-                                     ? PT_ATTACHED : 0);
+       task->ptrace = PT_PTRACED;
        if (capable(CAP_SYS_PTRACE))
                task->ptrace |= PT_PTRACE_CAP;
-       task_unlock(task);
 
-       write_lock_irq(&tasklist_lock);
        __ptrace_link(task, current);
+       send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+       retval = 0;
+unlock_tasklist:
        write_unlock_irq(&tasklist_lock);
+unlock_creds:
+       mutex_unlock(&task->cred_guard_mutex);
+out:
+       return retval;
+}
 
-       force_sig_specific(SIGSTOP, task);
-       return 0;
+/**
+ * ptrace_traceme  --  helper for PTRACE_TRACEME
+ *
+ * Performs checks and sets PT_PTRACED.
+ * Should be used by all ptrace implementations for PTRACE_TRACEME.
+ */
+int ptrace_traceme(void)
+{
+       int ret = -EPERM;
 
-bad:
-       task_unlock(task);
-       return retval;
+       write_lock_irq(&tasklist_lock);
+       /* Are we already being traced? */
+       if (!current->ptrace) {
+               ret = security_ptrace_traceme(current->parent);
+               /*
+                * Check PF_EXITING to ensure ->real_parent has not passed
+                * exit_ptrace(). Otherwise we don't report the error but
+                * pretend ->real_parent untraces us right after return.
+                */
+               if (!ret && !(current->real_parent->flags & PF_EXITING)) {
+                       current->ptrace = PT_PTRACED;
+                       __ptrace_link(current, current->real_parent);
+               }
+       }
+       write_unlock_irq(&tasklist_lock);
+
+       return ret;
+}
+
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
+{
+       int ret;
+       spin_lock(&sigh->siglock);
+       ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+             (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+       spin_unlock(&sigh->siglock);
+       return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping.  Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do. But if our normal
+ * children self-reap, then this child was prevented by ptrace and we must
+ * reap it now, in that case we must also wake up sub-threads sleeping in
+ * do_wait().
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+       __ptrace_unlink(p);
+
+       if (p->exit_state == EXIT_ZOMBIE) {
+               if (!task_detached(p) && thread_group_empty(p)) {
+                       if (!same_thread_group(p->real_parent, tracer))
+                               do_notify_parent(p, p->exit_signal);
+                       else if (ignoring_children(tracer->sighand)) {
+                               __wake_up_parent(p, tracer);
+                               p->exit_signal = -1;
+                       }
+               }
+               if (task_detached(p)) {
+                       /* Mark it as in the process of being reaped. */
+                       p->exit_state = EXIT_DEAD;
+                       return true;
+               }
+       }
+
+       return false;
 }
 
 int ptrace_detach(struct task_struct *child, unsigned int data)
 {
+       bool dead = false;
+
        if (!valid_signal(data))
-               return  -EIO;
+               return -EIO;
 
        /* Architecture-specific hardware disable .. */
        ptrace_disable(child);
-
-       /* .. re-parent .. */
-       child->exit_code = data;
+       clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 
        write_lock_irq(&tasklist_lock);
-       __ptrace_unlink(child);
-       /* .. and wake it up. */
-       if (child->exit_state != EXIT_ZOMBIE)
-               wake_up_process(child);
+       /*
+        * This child can be already killed. Make sure de_thread() or
+        * our sub-thread doing do_wait() didn't do release_task() yet.
+        */
+       if (child->ptrace) {
+               child->exit_code = data;
+               dead = __ptrace_detach(current, child);
+               if (!child->exit_state)
+                       wake_up_process(child);
+       }
        write_unlock_irq(&tasklist_lock);
 
+       if (unlikely(dead))
+               release_task(child);
+
        return 0;
 }
 
 /*
- * Access another process' address space.
- * Source/target buffer must be kernel space, 
- * Do not walk the page table directly, use get_user_pages
+ * Detach all tasks we were using ptrace on.
  */
-
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+void exit_ptrace(struct task_struct *tracer)
 {
-       struct mm_struct *mm;
-       struct vm_area_struct *vma;
-       struct page *page;
-       void *old_buf = buf;
+       struct task_struct *p, *n;
+       LIST_HEAD(ptrace_dead);
 
-       mm = get_task_mm(tsk);
-       if (!mm)
-               return 0;
+       write_lock_irq(&tasklist_lock);
+       list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+               if (__ptrace_detach(tracer, p))
+                       list_add(&p->ptrace_entry, &ptrace_dead);
+       }
+       write_unlock_irq(&tasklist_lock);
 
-       down_read(&mm->mmap_sem);
-       /* ignore errors, just check how much was sucessfully transfered */
-       while (len) {
-               int bytes, ret, offset;
-               void *maddr;
-
-               ret = get_user_pages(tsk, mm, addr, 1,
-                               write, 1, &page, &vma);
-               if (ret <= 0)
-                       break;
-
-               bytes = len;
-               offset = addr & (PAGE_SIZE-1);
-               if (bytes > PAGE_SIZE-offset)
-                       bytes = PAGE_SIZE-offset;
-
-               maddr = kmap(page);
-               if (write) {
-                       copy_to_user_page(vma, page, addr,
-                                         maddr + offset, buf, bytes);
-                       set_page_dirty_lock(page);
-               } else {
-                       copy_from_user_page(vma, page, addr,
-                                           buf, maddr + offset, bytes);
-               }
-               kunmap(page);
-               page_cache_release(page);
-               len -= bytes;
-               buf += bytes;
-               addr += bytes;
+       BUG_ON(!list_empty(&tracer->ptraced));
+
+       list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+               list_del_init(&p->ptrace_entry);
+               release_task(p);
        }
-       up_read(&mm->mmap_sem);
-       mmput(mm);
-       
-       return buf - old_buf;
 }
 
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
@@ -278,7 +367,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
                copied += retval;
                src += retval;
                dst += retval;
-               len -= retval;                  
+               len -= retval;
        }
        return copied;
 }
@@ -303,7 +392,7 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
                copied += retval;
                src += retval;
                dst += retval;
-               len -= retval;                  
+               len -= retval;
        }
        return copied;
 }
@@ -336,55 +425,106 @@ static int ptrace_setoptions(struct task_struct *child, long data)
        return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 }
 
-static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 {
-       siginfo_t lastinfo;
+       unsigned long flags;
        int error = -ESRCH;
 
-       read_lock(&tasklist_lock);
-       if (likely(child->sighand != NULL)) {
+       if (lock_task_sighand(child, &flags)) {
                error = -EINVAL;
-               spin_lock_irq(&child->sighand->siglock);
                if (likely(child->last_siginfo != NULL)) {
-                       lastinfo = *child->last_siginfo;
+                       *info = *child->last_siginfo;
                        error = 0;
                }
-               spin_unlock_irq(&child->sighand->siglock);
+               unlock_task_sighand(child, &flags);
        }
-       read_unlock(&tasklist_lock);
-       if (!error)
-               return copy_siginfo_to_user(data, &lastinfo);
        return error;
 }
 
-static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
+static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 {
-       siginfo_t newinfo;
+       unsigned long flags;
        int error = -ESRCH;
 
-       if (copy_from_user(&newinfo, data, sizeof (siginfo_t)))
-               return -EFAULT;
-
-       read_lock(&tasklist_lock);
-       if (likely(child->sighand != NULL)) {
+       if (lock_task_sighand(child, &flags)) {
                error = -EINVAL;
-               spin_lock_irq(&child->sighand->siglock);
                if (likely(child->last_siginfo != NULL)) {
-                       *child->last_siginfo = newinfo;
+                       *child->last_siginfo = *info;
                        error = 0;
                }
-               spin_unlock_irq(&child->sighand->siglock);
+               unlock_task_sighand(child, &flags);
        }
-       read_unlock(&tasklist_lock);
        return error;
 }
 
+
+#ifdef PTRACE_SINGLESTEP
+#define is_singlestep(request)         ((request) == PTRACE_SINGLESTEP)
+#else
+#define is_singlestep(request)         0
+#endif
+
+#ifdef PTRACE_SINGLEBLOCK
+#define is_singleblock(request)                ((request) == PTRACE_SINGLEBLOCK)
+#else
+#define is_singleblock(request)                0
+#endif
+
+#ifdef PTRACE_SYSEMU
+#define is_sysemu_singlestep(request)  ((request) == PTRACE_SYSEMU_SINGLESTEP)
+#else
+#define is_sysemu_singlestep(request)  0
+#endif
+
+static int ptrace_resume(struct task_struct *child, long request, long data)
+{
+       if (!valid_signal(data))
+               return -EIO;
+
+       if (request == PTRACE_SYSCALL)
+               set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+       else
+               clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+#ifdef TIF_SYSCALL_EMU
+       if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
+               set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+       else
+               clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#endif
+
+       if (is_singleblock(request)) {
+               if (unlikely(!arch_has_block_step()))
+                       return -EIO;
+               user_enable_block_step(child);
+       } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
+               if (unlikely(!arch_has_single_step()))
+                       return -EIO;
+               user_enable_single_step(child);
+       } else {
+               user_disable_single_step(child);
+       }
+
+       child->exit_code = data;
+       wake_up_process(child);
+
+       return 0;
+}
+
 int ptrace_request(struct task_struct *child, long request,
                   long addr, long data)
 {
        int ret = -EIO;
+       siginfo_t siginfo;
 
        switch (request) {
+       case PTRACE_PEEKTEXT:
+       case PTRACE_PEEKDATA:
+               return generic_ptrace_peekdata(child, addr, data);
+       case PTRACE_POKETEXT:
+       case PTRACE_POKEDATA:
+               return generic_ptrace_pokedata(child, addr, data);
+
 #ifdef PTRACE_OLDSETOPTIONS
        case PTRACE_OLDSETOPTIONS:
 #endif
@@ -394,12 +534,45 @@ int ptrace_request(struct task_struct *child, long request,
        case PTRACE_GETEVENTMSG:
                ret = put_user(child->ptrace_message, (unsigned long __user *) data);
                break;
+
        case PTRACE_GETSIGINFO:
-               ret = ptrace_getsiginfo(child, (siginfo_t __user *) data);
+               ret = ptrace_getsiginfo(child, &siginfo);
+               if (!ret)
+                       ret = copy_siginfo_to_user((siginfo_t __user *) data,
+                                                  &siginfo);
                break;
+
        case PTRACE_SETSIGINFO:
-               ret = ptrace_setsiginfo(child, (siginfo_t __user *) data);
+               if (copy_from_user(&siginfo, (siginfo_t __user *) data,
+                                  sizeof siginfo))
+                       ret = -EFAULT;
+               else
+                       ret = ptrace_setsiginfo(child, &siginfo);
+               break;
+
+       case PTRACE_DETACH:      /* detach a process that was attached. */
+               ret = ptrace_detach(child, data);
                break;
+
+#ifdef PTRACE_SINGLESTEP
+       case PTRACE_SINGLESTEP:
+#endif
+#ifdef PTRACE_SINGLEBLOCK
+       case PTRACE_SINGLEBLOCK:
+#endif
+#ifdef PTRACE_SYSEMU
+       case PTRACE_SYSEMU:
+       case PTRACE_SYSEMU_SINGLESTEP:
+#endif
+       case PTRACE_SYSCALL:
+       case PTRACE_CONT:
+               return ptrace_resume(child, request, data);
+
+       case PTRACE_KILL:
+               if (child->exit_state)  /* already dead */
+                       return 0;
+               return ptrace_resume(child, request, SIGKILL);
+
        default:
                break;
        }
@@ -407,55 +580,147 @@ int ptrace_request(struct task_struct *child, long request,
        return ret;
 }
 
-#ifndef __ARCH_SYS_PTRACE
-static int ptrace_get_task_struct(long request, long pid,
-               struct task_struct **childp)
+static struct task_struct *ptrace_get_task_struct(pid_t pid)
 {
        struct task_struct *child;
-       int ret;
+
+       rcu_read_lock();
+       child = find_task_by_vpid(pid);
+       if (child)
+               get_task_struct(child);
+       rcu_read_unlock();
+
+       if (!child)
+               return ERR_PTR(-ESRCH);
+       return child;
+}
+
+#ifndef arch_ptrace_attach
+#define arch_ptrace_attach(child)      do { } while (0)
+#endif
+
+SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
+{
+       struct task_struct *child;
+       long ret;
 
        /*
-        * Callers use child == NULL as an indication to exit early even
-        * when the return value is 0, so make sure it is non-NULL here.
+        * This lock_kernel fixes a subtle race with suid exec
         */
-       *childp = NULL;
-
+       lock_kernel();
        if (request == PTRACE_TRACEME) {
+               ret = ptrace_traceme();
+               if (!ret)
+                       arch_ptrace_attach(current);
+               goto out;
+       }
+
+       child = ptrace_get_task_struct(pid);
+       if (IS_ERR(child)) {
+               ret = PTR_ERR(child);
+               goto out;
+       }
+
+       if (request == PTRACE_ATTACH) {
+               ret = ptrace_attach(child);
                /*
-                * Are we already being traced?
-                */
-               if (current->ptrace & PT_PTRACED)
-                       return -EPERM;
-               ret = security_ptrace(current->parent, current);
-               if (ret)
-                       return -EPERM;
-               /*
-                * Set the ptrace bit in the process ptrace flags.
+                * Some architectures need to do book-keeping after
+                * a ptrace attach.
                 */
-               current->ptrace |= PT_PTRACED;
-               return 0;
+               if (!ret)
+                       arch_ptrace_attach(child);
+               goto out_put_task_struct;
        }
 
-       /*
-        * You may not mess with init
-        */
-       if (pid == 1)
-               return -EPERM;
+       ret = ptrace_check_attach(child, request == PTRACE_KILL);
+       if (ret < 0)
+               goto out_put_task_struct;
 
-       ret = -ESRCH;
-       read_lock(&tasklist_lock);
-       child = find_task_by_pid(pid);
-       if (child)
-               get_task_struct(child);
-       read_unlock(&tasklist_lock);
-       if (!child)
-               return -ESRCH;
+       ret = arch_ptrace(child, request, addr, data);
 
-       *childp = child;
-       return 0;
+ out_put_task_struct:
+       put_task_struct(child);
+ out:
+       unlock_kernel();
+       return ret;
+}
+
+int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
+{
+       unsigned long tmp;
+       int copied;
+
+       copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
+       if (copied != sizeof(tmp))
+               return -EIO;
+       return put_user(tmp, (unsigned long __user *)data);
+}
+
+int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
+{
+       int copied;
+
+       copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
+       return (copied == sizeof(data)) ? 0 : -EIO;
+}
+
+#if defined CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_ptrace_request(struct task_struct *child, compat_long_t request,
+                         compat_ulong_t addr, compat_ulong_t data)
+{
+       compat_ulong_t __user *datap = compat_ptr(data);
+       compat_ulong_t word;
+       siginfo_t siginfo;
+       int ret;
+
+       switch (request) {
+       case PTRACE_PEEKTEXT:
+       case PTRACE_PEEKDATA:
+               ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+               if (ret != sizeof(word))
+                       ret = -EIO;
+               else
+                       ret = put_user(word, datap);
+               break;
+
+       case PTRACE_POKETEXT:
+       case PTRACE_POKEDATA:
+               ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+               ret = (ret != sizeof(data) ? -EIO : 0);
+               break;
+
+       case PTRACE_GETEVENTMSG:
+               ret = put_user((compat_ulong_t) child->ptrace_message, datap);
+               break;
+
+       case PTRACE_GETSIGINFO:
+               ret = ptrace_getsiginfo(child, &siginfo);
+               if (!ret)
+                       ret = copy_siginfo_to_user32(
+                               (struct compat_siginfo __user *) datap,
+                               &siginfo);
+               break;
+
+       case PTRACE_SETSIGINFO:
+               memset(&siginfo, 0, sizeof siginfo);
+               if (copy_siginfo_from_user32(
+                           &siginfo, (struct compat_siginfo __user *) datap))
+                       ret = -EFAULT;
+               else
+                       ret = ptrace_setsiginfo(child, &siginfo);
+               break;
+
+       default:
+               ret = ptrace_request(child, request, addr, data);
+       }
+
+       return ret;
 }
 
-asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
+asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
+                                 compat_long_t addr, compat_long_t data)
 {
        struct task_struct *child;
        long ret;
@@ -464,22 +729,31 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
         * This lock_kernel fixes a subtle race with suid exec
         */
        lock_kernel();
-       ret = ptrace_get_task_struct(request, pid, &child);
-       if (!child)
+       if (request == PTRACE_TRACEME) {
+               ret = ptrace_traceme();
                goto out;
+       }
 
-       if (request == PTRACE_ATTACH) {
-               ret = ptrace_attach(child);
+       child = ptrace_get_task_struct(pid);
+       if (IS_ERR(child)) {
+               ret = PTR_ERR(child);
                goto out;
        }
 
-       ret = ptrace_check_attach(child, request == PTRACE_KILL);
-       if (ret < 0)
+       if (request == PTRACE_ATTACH) {
+               ret = ptrace_attach(child);
+               /*
+                * Some architectures need to do book-keeping after
+                * a ptrace attach.
+                */
+               if (!ret)
+                       arch_ptrace_attach(child);
                goto out_put_task_struct;
+       }
 
-       ret = arch_ptrace(child, request, addr, data);
-       if (ret < 0)
-               goto out_put_task_struct;
+       ret = ptrace_check_attach(child, request == PTRACE_KILL);
+       if (!ret)
+               ret = compat_arch_ptrace(child, request, addr, data);
 
  out_put_task_struct:
        put_task_struct(child);
@@ -487,4 +761,4 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
        unlock_kernel();
        return ret;
 }
-#endif /* __ARCH_SYS_PTRACE */
+#endif /* CONFIG_COMPAT */