[PATCH v3 1/3] clone: Add clone_arg field for shadow stack

[Yury Khrustalev]

Corresponding change in the kernel was proposed in
https://lore.kernel.org/all/20250916-clone3-shadow-stack-v21-0-910493527013@kernel.org/
---
 sysdeps/unix/sysv/linux/clone-internal.c | 7 +++++--
 sysdeps/unix/sysv/linux/clone3.h         | 2 ++
 sysdeps/unix/sysv/linux/spawni.c         | 1 +
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c
index 9a1f27d017..a61645cad2 100644
--- a/sysdeps/unix/sysv/linux/clone-internal.c
+++ b/sysdeps/unix/sysv/linux/clone-internal.c
@@ -27,6 +27,7 @@
 #define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
 #define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */
 #define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */
+#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */
 
 #define sizeof_field(TYPE, MEMBER) sizeof ((((TYPE *)0)->MEMBER))
 #define offsetofend(TYPE, MEMBER) \
@@ -40,8 +41,10 @@ _Static_assert (offsetofend (struct clone_args, set_tid_size) == CLONE_ARGS_SIZE
 		"offsetofend (struct clone_args, set_tid_size) != CLONE_ARGS_SIZE_VER1");
 _Static_assert (offsetofend (struct clone_args, cgroup) == CLONE_ARGS_SIZE_VER2,
 		"offsetofend (struct clone_args, cgroup) != CLONE_ARGS_SIZE_VER2");
-_Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER2,
-		"sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER2");
+_Static_assert (offsetofend (struct clone_args, shadow_stack_token) == CLONE_ARGS_SIZE_VER3,
+		"offsetofend (struct clone_args, shadow_stack) != CLONE_ARGS_SIZE_VER3");
+_Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER3,
+		"sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER3");
 
 int
 __clone_internal_fallback (struct clone_args *cl_args,
diff --git a/sysdeps/unix/sysv/linux/clone3.h b/sysdeps/unix/sysv/linux/clone3.h
index 847ca96d0d..d964a84fa0 100644
--- a/sysdeps/unix/sysv/linux/clone3.h
+++ b/sysdeps/unix/sysv/linux/clone3.h
@@ -61,6 +61,8 @@ struct clone_args
   __aligned_uint64_t set_tid_size;
   /* File descriptor for target cgroup of child (since Linux 5.7).  */
   __aligned_uint64_t cgroup;
+  /* Shadow stack support (since Linux 6.17).  */
+  __aligned_uint64_t shadow_stack_token;
 };
 
 #endif /* clone3.h */
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index bc8476ff11..b80fb0ca20 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -412,6 +412,7 @@ __spawnix (int *pid, const char *file,
       /* This is require for clone fallback, where pidfd is returned
 	 on parent_tid.  */
       .parent_tid = use_pidfd ? (uintptr_t) &args.pidfd : 0,
+      .shadow_stack_token = 0,
     };
 #ifdef HAVE_CLONE3_WRAPPER
   args.use_clone3 = true;
-- 
2.47.3