From f65dfec09650768626a9af916b0487afa557a930 Mon Sep 17 00:00:00 2001
From: Michael Pratt <mpratt@google.com>
Date: Wed, 22 May 2019 18:10:54 -0700
Subject: Add WCLONE / WALL support to waitid

The previous commit adds WNOTHREAD support to waitid, so we may as well
complete the upstream change.

Linux added WCLONE, WALL, WNOTHREAD support to waitid(2) in
91c4e8ea8f05916df0c8a6f383508ac7c9e10dba ("wait: allow sys_waitid() to
accept __WNOTHREAD/__WCLONE/__WALL"). i.e., Linux 4.7.

PiperOrigin-RevId: 249560587
Change-Id: Iff177b0848a3f7bae6cb5592e44500c5a942fbeb
---
 pkg/sentry/syscalls/linux/sys_thread.go | 67 +++++++++++++++++----------------
 1 file changed, 35 insertions(+), 32 deletions(-)

(limited to 'pkg/sentry/syscalls')

diff --git a/pkg/sentry/syscalls/linux/sys_thread.go b/pkg/sentry/syscalls/linux/sys_thread.go
index 14fa7ef92..26f7e8ead 100644
--- a/pkg/sentry/syscalls/linux/sys_thread.go
+++ b/pkg/sentry/syscalls/linux/sys_thread.go
@@ -181,6 +181,32 @@ func Vfork(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	return clone(t, syscall.CLONE_VM|syscall.CLONE_VFORK|int(syscall.SIGCHLD), 0, 0, 0, 0)
 }
 
+// parseCommonWaitOptions applies the options common to wait4 and waitid to
+// wopts.
+func parseCommonWaitOptions(wopts *kernel.WaitOptions, options int) error {
+	switch options & (linux.WCLONE | linux.WALL) {
+	case 0:
+		wopts.NonCloneTasks = true
+	case linux.WCLONE:
+		wopts.CloneTasks = true
+	case linux.WALL:
+		wopts.NonCloneTasks = true
+		wopts.CloneTasks = true
+	default:
+		return syscall.EINVAL
+	}
+	if options&linux.WCONTINUED != 0 {
+		wopts.Events |= kernel.EventGroupContinue
+	}
+	if options&linux.WNOHANG == 0 {
+		wopts.BlockInterruptErr = kernel.ERESTARTSYS
+	}
+	if options&linux.WNOTHREAD == 0 {
+		wopts.SiblingChildren = true
+	}
+	return nil
+}
+
 // wait4 waits for the given child process to exit.
 func wait4(t *kernel.Task, pid int, statusAddr usermem.Addr, options int, rusageAddr usermem.Addr) (uintptr, error) {
 	if options&^(linux.WNOHANG|linux.WUNTRACED|linux.WCONTINUED|linux.WNOTHREAD|linux.WALL|linux.WCLONE) != 0 {
@@ -207,29 +233,12 @@ func wait4(t *kernel.Task, pid int, statusAddr usermem.Addr, options int, rusage
 		wopts.SpecificTID = kernel.ThreadID(pid)
 	}
 
-	switch options & (linux.WCLONE | linux.WALL) {
-	case 0:
-		wopts.NonCloneTasks = true
-	case linux.WCLONE:
-		wopts.CloneTasks = true
-	case linux.WALL:
-		wopts.NonCloneTasks = true
-		wopts.CloneTasks = true
-	default:
-		return 0, syscall.EINVAL
+	if err := parseCommonWaitOptions(&wopts, options); err != nil {
+		return 0, err
 	}
 	if options&linux.WUNTRACED != 0 {
 		wopts.Events |= kernel.EventChildGroupStop
 	}
-	if options&linux.WCONTINUED != 0 {
-		wopts.Events |= kernel.EventGroupContinue
-	}
-	if options&linux.WNOHANG == 0 {
-		wopts.BlockInterruptErr = kernel.ERESTARTSYS
-	}
-	if options&linux.WNOTHREAD == 0 {
-		wopts.SiblingChildren = true
-	}
 
 	wr, err := t.Wait(&wopts)
 	if err != nil {
@@ -281,16 +290,15 @@ func Waitid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	options := int(args[3].Uint())
 	rusageAddr := args[4].Pointer()
 
-	if options&^(linux.WNOHANG|linux.WEXITED|linux.WSTOPPED|linux.WCONTINUED|linux.WNOWAIT|linux.WNOTHREAD) != 0 {
+	if options&^(linux.WNOHANG|linux.WEXITED|linux.WSTOPPED|linux.WCONTINUED|linux.WNOWAIT|linux.WNOTHREAD|linux.WALL|linux.WCLONE) != 0 {
 		return 0, nil, syscall.EINVAL
 	}
 	if options&(linux.WEXITED|linux.WSTOPPED|linux.WCONTINUED) == 0 {
 		return 0, nil, syscall.EINVAL
 	}
 	wopts := kernel.WaitOptions{
-		NonCloneTasks: true,
-		Events:        kernel.EventTraceeStop,
-		ConsumeEvent:  options&linux.WNOWAIT == 0,
+		Events:       kernel.EventTraceeStop,
+		ConsumeEvent: options&linux.WNOWAIT == 0,
 	}
 	switch idtype {
 	case linux.P_ALL:
@@ -301,21 +309,16 @@ func Waitid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	default:
 		return 0, nil, syscall.EINVAL
 	}
+
+	if err := parseCommonWaitOptions(&wopts, options); err != nil {
+		return 0, nil, err
+	}
 	if options&linux.WEXITED != 0 {
 		wopts.Events |= kernel.EventExit
 	}
 	if options&linux.WSTOPPED != 0 {
 		wopts.Events |= kernel.EventChildGroupStop
 	}
-	if options&linux.WCONTINUED != 0 {
-		wopts.Events |= kernel.EventGroupContinue
-	}
-	if options&linux.WNOHANG == 0 {
-		wopts.BlockInterruptErr = kernel.ERESTARTSYS
-	}
-	if options&linux.WNOTHREAD == 0 {
-		wopts.SiblingChildren = true
-	}
 
 	wr, err := t.Wait(&wopts)
 	if err != nil {
-- 
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