5 files changed, 36 insertions, 8 deletions

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 4927bb69387a..d7ae81b10893 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -140,9 +140,12 @@ enum {
  * IORING_SQ_TASKRUN in the sq ring flags. Not valid with COOP_TASKRUN.
  */
 #define IORING_SETUP_TASKRUN_FLAG	(1U << 9)
-
 #define IORING_SETUP_SQE128		(1U << 10) /* SQEs are 128 byte */
 #define IORING_SETUP_CQE32		(1U << 11) /* CQEs are 32 byte */
+/*
+ * Only one task is allowed to submit requests
+ */
+#define IORING_SETUP_SINGLE_ISSUER	(1U << 12)
 
 enum io_uring_op {
 	IORING_OP_NOP,
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 85a479594b05..06772139b7da 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2457,6 +2457,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_destroy_buffers(ctx);
 	if (ctx->sq_creds)
 		put_cred(ctx->sq_creds);
+	if (ctx->submitter_task)
+		put_task_struct(ctx->submitter_task);
 
 	/* there are no registered resources left, nobody uses it */
 	if (ctx->rsrc_node)
@@ -3189,7 +3191,7 @@ static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
 	if (fd < 0)
 		return fd;
 
-	ret = io_uring_add_tctx_node(ctx);
+	ret = __io_uring_add_tctx_node(ctx, false);
 	if (ret) {
 		put_unused_fd(fd);
 		return ret;
@@ -3409,7 +3411,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
 			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
 			IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
 			IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
-			IORING_SETUP_SQE128 | IORING_SETUP_CQE32))
+			IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
+			IORING_SETUP_SINGLE_ISSUER))
 		return -EINVAL;
 
 	return io_uring_create(entries, &p, params);
diff --git a/io_uring/io_uring_types.h b/io_uring/io_uring_types.h
index 1f8db2dd7af7..8b00243abf65 100644
--- a/io_uring/io_uring_types.h
+++ b/io_uring/io_uring_types.h
@@ -243,6 +243,7 @@ struct io_ring_ctx {
 	/* Keep this last, we don't need it for the fast path */
 
 	struct io_restriction		restrictions;
+	struct task_struct		*submitter_task;
 
 	/* slow path rsrc auxilary data, used by update/register */
 	struct io_rsrc_node		*rsrc_backup_node;
diff --git a/io_uring/tctx.c b/io_uring/tctx.c
index 5a5d4f908529..a819da8fc85c 100644
--- a/io_uring/tctx.c
+++ b/io_uring/tctx.c
@@ -94,12 +94,32 @@ __cold int io_uring_alloc_task_context(struct task_struct *task,
 	return 0;
 }
 
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
+static int io_register_submitter(struct io_ring_ctx *ctx)
+{
+	int ret = 0;
+
+	mutex_lock(&ctx->uring_lock);
+	if (!ctx->submitter_task)
+		ctx->submitter_task = get_task_struct(current);
+	else if (ctx->submitter_task != current)
+		ret = -EEXIST;
+	mutex_unlock(&ctx->uring_lock);
+
+	return ret;
+}
+
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter)
 {
 	struct io_uring_task *tctx = current->io_uring;
 	struct io_tctx_node *node;
 	int ret;
 
+	if ((ctx->flags & IORING_SETUP_SINGLE_ISSUER) && submitter) {
+		ret = io_register_submitter(ctx);
+		if (ret)
+			return ret;
+	}
+
 	if (unlikely(!tctx)) {
 		ret = io_uring_alloc_task_context(current, ctx);
 		if (unlikely(ret))
@@ -133,7 +153,8 @@ int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
 		list_add(&node->ctx_node, &ctx->tctx_list);
 		mutex_unlock(&ctx->uring_lock);
 	}
-	tctx->last = ctx;
+	if (submitter)
+		tctx->last = ctx;
 	return 0;
 }
 
@@ -241,7 +262,7 @@ int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg,
 		return -EINVAL;
 
 	mutex_unlock(&ctx->uring_lock);
-	ret = io_uring_add_tctx_node(ctx);
+	ret = __io_uring_add_tctx_node(ctx, false);
 	mutex_lock(&ctx->uring_lock);
 	if (ret)
 		return ret;
diff --git a/io_uring/tctx.h b/io_uring/tctx.h
index 7684713e950f..dde82ce4d8e2 100644
--- a/io_uring/tctx.h
+++ b/io_uring/tctx.h
@@ -34,7 +34,7 @@ struct io_tctx_node {
 int io_uring_alloc_task_context(struct task_struct *task,
 				struct io_ring_ctx *ctx);
 void io_uring_del_tctx_node(unsigned long index);
-int __io_uring_add_tctx_node(struct io_ring_ctx *ctx);
+int __io_uring_add_tctx_node(struct io_ring_ctx *ctx, bool submitter);
 void io_uring_clean_tctx(struct io_uring_task *tctx);
 
 void io_uring_unreg_ringfd(void);
@@ -52,5 +52,5 @@ static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx)
 
 	if (likely(tctx && tctx->last == ctx))
 		return 0;
-	return __io_uring_add_tctx_node(ctx);
+	return __io_uring_add_tctx_node(ctx, true);
 }