[PATCH for-next 1/1] io_uring: limit registration w/ SINGLE_ISSUER

[Pavel Begunkov <asml.silence@gmail.com>]

IORING_SETUP_SINGLE_ISSUER restricts what tasks can submit requests.
Extend it to registration as well, so non-owning task can't do
registrations. It's not necessary at the moment but might be useful in
the future.

Cc: <stable@vger.kernel.org> # 6.0
Fixes: 97bbdc06a444 ("io_uring: add IORING_SETUP_SINGLE_ISSUER")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 73ac6948debb..3f6eb3cf07ac 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3890,6 +3890,9 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 	if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
 		return -ENXIO;
 
+	if (ctx->submitter_task && ctx->submitter_task != current)
+		return -EEXIST;
+
 	if (ctx->restricted) {
 		if (opcode >= IORING_REGISTER_LAST)
 			return -EINVAL;
-- 
2.37.2