[PATCH 5/5] sockptr: introduce copy_struct_to_sockptr()

[Stefan Metzmacher]

We already have copy_struct_from_sockptr() as wrapper to
copy_struct_from_user() or copy_struct_from_bounce_buffer(),
so it's good to have copy_struct_to_sockptr()
as well matching the behavior of copy_struct_to_user()
or copy_struct_to_bounce_buffer().

The world would be better without sockptr_t, but having
copy_struct_to_sockptr() is better than open code it
in various places.

I'll use this in my IPPROTO_SMBDIRECT work,
but maybe it will also be useful for others...
IPPROTO_QUIC will likely also use it.

Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Dmitry Safonov <dima@xxxxxxxxxx>
Cc: Francesco Ruggeri <fruggeri@xxxxxxxxxx>
Cc: Salam Noureddine <noureddine@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Michal Luczaj <mhal@xxxxxxx>
Cc: David Wei <dw@xxxxxxxxxxx>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Cc: Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>
Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Cc: Xin Long <lucien.xin@xxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Willem de Bruijn <willemb@xxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Simon Horman <horms@xxxxxxxxxx>
Cc: Aleksa Sarai <cyphar@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
CC: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-bluetooth@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Stefan Metzmacher <metze@xxxxxxxxx>
---
 include/linux/sockptr.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
index 706a8526cf3c..9c2429c1a570 100644
--- a/include/linux/sockptr.h
+++ b/include/linux/sockptr.h
@@ -107,6 +107,16 @@ static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t size)
 	return copy_to_sockptr_offset(dst, 0, src, size);
 }
 
+static inline int
+copy_struct_to_sockptr(sockptr_t dst, size_t usize, const void *src,
+		       size_t ksize, bool *ignored_trailing)
+{
+	if (!sockptr_is_kernel(dst))
+		return copy_struct_to_user(dst.user, usize, src, ksize, ignored_trailing);
+
+	return copy_struct_to_bounce_buffer(dst.kernel, usize, src, ksize, ignored_trailing);
+}
+
 static inline void *memdup_sockptr_noprof(sockptr_t src, size_t len)
 {
 	void *p = kmalloc_track_caller_noprof(len, GFP_USER | __GFP_NOWARN);
-- 
2.43.0