1 files changed, 28 insertions, 13 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8dcb8f6288bc..019e04ec065a 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -118,6 +118,33 @@ int ptrace_check_attach(struct task_struct *child, int kill)
         return ret;
 }
 
+static int may_attach(struct task_struct *task)
+{
+        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))
+                return -EPERM;
+        smp_rmb();
+        if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+                return -EPERM;
+
+        return security_ptrace(current, task);
+}
+
+int ptrace_may_attach(struct task_struct *task)
+{
+        int err;
+        task_lock(task);
+        err = may_attach(task);
+        task_unlock(task);
+        return !err;
+}
+
 int ptrace_attach(struct task_struct *task)
 {
         int retval;
@@ -127,22 +154,10 @@ int ptrace_attach(struct task_struct *task)
                 goto bad;
         if (task == current)
                 goto bad;
-        if (!task->mm)
-                goto bad;
-        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))
-                goto bad;
-        smp_rmb();
-        if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
-                goto bad;
         /* the same process cannot be attached many times */
         if (task->ptrace & PT_PTRACED)
                 goto bad;
-        retval = security_ptrace(current, task);
+        retval = may_attach(task);
         if (retval)
                 goto bad;