exec: kill task_struct->did_exec

We can kill either task->did_exec or PF_FORKNOEXEC, they are mutually
exclusive.  The patch kills ->did_exec because it has a single user.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 2 insertions, 6 deletions

diff --git a/fs/exec.c b/fs/exec.c
index f860866e04ba..493b102a27c1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1424,7 +1424,6 @@ static int exec_binprm(struct linux_binprm *bprm)
                 audit_bprm(bprm);
                 trace_sched_process_exec(current, old_pid, bprm);
                 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
-                current->did_exec = 1;
                 proc_exec_connector(current);
         }
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 66a17ad55bcb..68a0e84463a0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1239,7 +1239,6 @@ struct task_struct {
         /* Used for emulating ABI behavior of previous Linux versions */
         unsigned int personality;
 
-        unsigned did_exec:1;
         unsigned in_execve:1;   /* Tell the LSMs that the process is doing an
                                  * execve */
         unsigned in_iowait:1;
diff --git a/kernel/fork.c b/kernel/fork.c
index b6dd0bbf4240..a17621c6cd42 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1226,7 +1226,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         if (!try_module_get(task_thread_info(p)->exec_domain->module))
                 goto bad_fork_cleanup_count;
 
-        p->did_exec = 0;
         delayacct_tsk_init(p);  /* Must remain after dup_task_struct() */
         copy_flags(clone_flags, p);
         INIT_LIST_HEAD(&p->children);
diff --git a/kernel/sys.c b/kernel/sys.c
index c72311324ea7..ecd3ea12f72a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -895,8 +895,7 @@ SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
  * only important on a multi-user system anyway, to make sure one user
  * can't send a signal to a process owned by another.  -TYT, 12/12/91
  *
- * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
- * LBT 04.03.94
+ * !PF_FORKNOEXEC check to conform completely to POSIX.
  */
 SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
 {
@@ -932,7 +931,7 @@ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
                 if (task_session(p) != task_session(group_leader))
                         goto out;
                 err = -EACCES;
-                if (p->did_exec)
+                if (!(p->flags & PF_FORKNOEXEC))
                         goto out;
         } else {
                 err = -ESRCH;