1 files changed, 29 insertions, 6 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 45a8a4c5d8b2..dcf9f974198c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -209,10 +209,28 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
         return !err;
 }
 
-static int ptrace_attach(struct task_struct *task)
+static int ptrace_attach(struct task_struct *task, long request,
+                         unsigned long flags)
 {
+        bool seize = (request == PTRACE_SEIZE);
         int retval;
 
+        /*
+         * SEIZE will enable new ptrace behaviors which will be implemented
+         * gradually.  SEIZE_DEVEL is used to prevent applications
+         * expecting full SEIZE behaviors trapping on kernel commits which
+         * are still in the process of implementing them.
+         *
+         * Only test programs for new ptrace behaviors being implemented
+         * should set SEIZE_DEVEL.  If unset, SEIZE will fail with -EIO.
+         *
+         * Once SEIZE behaviors are completely implemented, this flag and
+         * the following test will be removed.
+         */
+        retval = -EIO;
+        if (seize && !(flags & PTRACE_SEIZE_DEVEL))
+                goto out;
+
         audit_ptrace(task);
 
         retval = -EPERM;
@@ -244,11 +262,16 @@ static int ptrace_attach(struct task_struct *task)
                 goto unlock_tasklist;
 
         task->ptrace = PT_PTRACED;
+        if (seize)
+                task->ptrace |= PT_SEIZED;
         if (task_ns_capable(task, CAP_SYS_PTRACE))
                 task->ptrace |= PT_PTRACE_CAP;
 
         __ptrace_link(task, current);
-        send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+        /* SEIZE doesn't trap tracee on attach */
+        if (!seize)
+                send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 
         spin_lock(&task->sighand->siglock);
 
@@ -785,8 +808,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
                 goto out;
         }
 
-        if (request == PTRACE_ATTACH) {
-                ret = ptrace_attach(child);
+        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+                ret = ptrace_attach(child, request, data);
                 /*
                  * Some architectures need to do book-keeping after
                  * a ptrace attach.
@@ -927,8 +950,8 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
                 goto out;
         }
 
-        if (request == PTRACE_ATTACH) {
-                ret = ptrace_attach(child);
+        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+                ret = ptrace_attach(child, request, data);
                 /*
                  * Some architectures need to do book-keeping after
                  * a ptrace attach.