sched/task: close file descriptor with O_CLOEXEC before active task or exec

VELAPLATFO-18473

refs:
https://man7.org/linux/man-pages/man2/fcntl.2.html
If the FD_CLOEXEC bit is set, the file descriptor will automatically
be closed during a successful execve(2).
(If the execve(2) fails, the file descriptor is left open.)

modify:
1. Ensure that the child task copies all fds of the parent task,
   including those with O_CLOEXE.
2. Make sure spawn_file_action is executed under fd with O_CLOEXEC,
   otherwise it will fail.
3. When a new task is activated or exec is called, close all fds
   with O_CLOEXEC flags.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

binfmt/binfmt_execmodule.c

@@ -34,6 +34,7 @@
 
 #include <nuttx/addrenv.h>
 #include <nuttx/arch.h>
+#include <nuttx/fs/fs.h>
 #include <nuttx/kmalloc.h>
 #include <nuttx/sched.h>
 #include <sched/sched.h>
@@ -375,6 +376,10 @@ int exec_module(FAR struct binary_s *binp,
     }
 #endif
 
+  /* Close the file descriptors with O_CLOEXEC before active task */
+
+  files_close_onexec(&tcb->cmn);
+
   if (!spawn)
     {
       exec_swap(this_task(), (FAR struct tcb_s *)tcb);

fs/inode/fs_files.c

@@ -462,8 +462,7 @@ int files_duplist(FAR struct filelist *plist, FAR struct filelist *clist)
 
           filep = &plist->fl_files[i][j];
 
-          if (filep && (filep->f_inode == NULL ||
+          if (filep && filep->f_inode == NULL)
-                       (filep->f_oflags & O_CLOEXEC) != 0))
             {
               continue;
             }
@@ -474,9 +473,10 @@ int files_duplist(FAR struct filelist *plist, FAR struct filelist *clist)
               goto out;
             }
 
-          /* Yes... duplicate it for the child */
+          /* Yes... duplicate it for the child, include O_CLOEXEC flag. */
 
-          ret = file_dup2(filep, &clist->fl_files[i][j]);
+          ret = file_dup3(filep, &clist->fl_files[i][j],
+                          filep->f_oflags & O_CLOEXEC ? O_CLOEXEC : 0);
           if (ret < 0)
             {
               goto out;
@@ -489,6 +489,44 @@ out:
   return ret;
 }
 
+/****************************************************************************
+ * Name: files_close_onexec
+ *
+ * Description:
+ *   Close specified task's file descriptors with O_CLOEXEC before exec.
+ *
+ ****************************************************************************/
+
+void files_close_onexec(FAR struct tcb_s *tcb)
+{
+  FAR struct filelist *list;
+  int i;
+  int j;
+
+  /* Get the file descriptor list.  It should not be NULL in this context. */
+
+  list = nxsched_get_files_from_tcb(tcb);
+  DEBUGASSERT(list != NULL);
+
+  nxmutex_lock(&list->fl_lock);
+  for (i = 0; i < list->fl_rows; i++)
+    {
+      for (j = 0; j < CONFIG_NFILE_DESCRIPTORS_PER_BLOCK; j++)
+        {
+          FAR struct file *filep;
+
+          filep = &list->fl_files[i][j];
+          if (filep && filep->f_inode != NULL &&
+              (filep->f_oflags & O_CLOEXEC) != 0)
+            {
+              file_close(filep);
+            }
+        }
+    }
+
+  nxmutex_unlock(&list->fl_lock);
+}
+
 /****************************************************************************
  * Name: fs_getfilep
  *

include/nuttx/fs/fs.h

@@ -865,6 +865,16 @@ void files_releaselist(FAR struct filelist *list);
 
 int files_duplist(FAR struct filelist *plist, FAR struct filelist *clist);
 
+/****************************************************************************
+ * Name: files_close_onexec
+ *
+ * Description:
+ *   Close specified task's file descriptors with O_CLOEXEC before exec.
+ *
+ ****************************************************************************/
+
+void files_close_onexec(FAR struct tcb_s *tcb);
+
 /****************************************************************************
  * Name: file_allocate_from_tcb
  *

sched/task/task_create.c

@@ -33,6 +33,7 @@
 #include <nuttx/kmalloc.h>
 #include <nuttx/sched.h>
 #include <nuttx/kthread.h>
+#include <nuttx/fs/fs.h>
 
 #include "sched/sched.h"
 #include "group/group.h"
@@ -102,6 +103,10 @@ int nxthread_create(FAR const char *name, uint8_t ttype, int priority,
       return ret;
     }
 
+  /* Close the file descriptors with O_CLOEXEC before active task */
+
+  files_close_onexec(&tcb->cmn);
+
   /* Get the assigned pid before we start the task */
 
   pid = tcb->cmn.pid;

sched/task/task_spawn.c

@@ -31,6 +31,7 @@
 #include <debug.h>
 #include <errno.h>
 
+#include <nuttx/fs/fs.h>
 #include <nuttx/sched.h>
 #include <nuttx/kthread.h>
 #include <nuttx/spawn.h>
@@ -125,6 +126,10 @@ static int nxtask_spawn_create(FAR const char *name, int priority,
         }
     }
 
+  /* Close the file descriptors with O_CLOEXEC before active task */
+
+  files_close_onexec(&tcb->cmn);
+
   /* Set the attributes */
 
   if (attr)