1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/kernel.h>
  3#include <linux/errno.h>
  4#include <linux/file.h>
  5#include <linux/slab.h>
  6#include <linux/nospec.h>
  7#include <linux/io_uring.h>
  8
  9#include <uapi/linux/io_uring.h>
 10
 11#include "io_uring.h"
 12#include "rsrc.h"
 13#include "filetable.h"
 14#include "alloc_cache.h"
 15#include "msg_ring.h"
 16
 17/* All valid masks for MSG_RING */
 18#define IORING_MSG_RING_MASK		(IORING_MSG_RING_CQE_SKIP | \
 19					IORING_MSG_RING_FLAGS_PASS)
 20
 21struct io_msg {
 22	struct file			*file;
 23	struct file			*src_file;
 24	struct callback_head		tw;
 25	u64 user_data;
 26	u32 len;
 27	u32 cmd;
 28	u32 src_fd;
 29	union {
 30		u32 dst_fd;
 31		u32 cqe_flags;
 32	};
 33	u32 flags;
 34};
 35
 36static void io_double_unlock_ctx(struct io_ring_ctx *octx)
 37{
 38	mutex_unlock(&octx->uring_lock);
 39}
 40
 41static int io_double_lock_ctx(struct io_ring_ctx *octx,
 42			      unsigned int issue_flags)
 43{
 44	/*
 45	 * To ensure proper ordering between the two ctxs, we can only
 46	 * attempt a trylock on the target. If that fails and we already have
 47	 * the source ctx lock, punt to io-wq.
 48	 */
 49	if (!(issue_flags & IO_URING_F_UNLOCKED)) {
 50		if (!mutex_trylock(&octx->uring_lock))
 51			return -EAGAIN;
 52		return 0;
 53	}
 54	mutex_lock(&octx->uring_lock);
 55	return 0;
 56}
 57
 58void io_msg_ring_cleanup(struct io_kiocb *req)
 59{
 60	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
 61
 62	if (WARN_ON_ONCE(!msg->src_file))
 63		return;
 64
 65	fput(msg->src_file);
 66	msg->src_file = NULL;
 67}
 68
 69static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx)
 70{
 71	return target_ctx->task_complete;
 72}
 73
 74static void io_msg_tw_complete(struct io_kiocb *req, struct io_tw_state *ts)
 75{
 76	struct io_ring_ctx *ctx = req->ctx;
 77
 78	io_add_aux_cqe(ctx, req->cqe.user_data, req->cqe.res, req->cqe.flags);
 79	if (spin_trylock(&ctx->msg_lock)) {
 80		if (io_alloc_cache_put(&ctx->msg_cache, req))
 81			req = NULL;
 82		spin_unlock(&ctx->msg_lock);
 83	}
 84	if (req)
 85		kmem_cache_free(req_cachep, req);
 86	percpu_ref_put(&ctx->refs);
 87}
 88
 89static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req,
 90			      int res, u32 cflags, u64 user_data)
 91{
 92	if (!READ_ONCE(ctx->submitter_task)) {
 93		kmem_cache_free(req_cachep, req);
 94		return -EOWNERDEAD;
 95	}
 96	req->cqe.user_data = user_data;
 97	io_req_set_res(req, res, cflags);
 98	percpu_ref_get(&ctx->refs);
 99	req->ctx = ctx;
100	req->tctx = NULL;
101	req->io_task_work.func = io_msg_tw_complete;
102	io_req_task_work_add_remote(req, ctx, IOU_F_TWQ_LAZY_WAKE);
103	return 0;
104}
105
106static struct io_kiocb *io_msg_get_kiocb(struct io_ring_ctx *ctx)
107{
108	struct io_kiocb *req = NULL;
109
110	if (spin_trylock(&ctx->msg_lock)) {
111		req = io_alloc_cache_get(&ctx->msg_cache);
112		spin_unlock(&ctx->msg_lock);
113		if (req)
114			return req;
115	}
116	return kmem_cache_alloc(req_cachep, GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO);
117}
118
119static int io_msg_data_remote(struct io_ring_ctx *target_ctx,
120			      struct io_msg *msg)
121{
122	struct io_kiocb *target;
123	u32 flags = 0;
124
125	target = io_msg_get_kiocb(target_ctx);
126	if (unlikely(!target))
127		return -ENOMEM;
128
129	if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
130		flags = msg->cqe_flags;
131
132	return io_msg_remote_post(target_ctx, target, msg->len, flags,
133					msg->user_data);
134}
135
136static int __io_msg_ring_data(struct io_ring_ctx *target_ctx,
137			      struct io_msg *msg, unsigned int issue_flags)
138{
139	u32 flags = 0;
140	int ret;
141
142	if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
143		return -EINVAL;
144	if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
145		return -EINVAL;
146	if (target_ctx->flags & IORING_SETUP_R_DISABLED)
147		return -EBADFD;
148
149	if (io_msg_need_remote(target_ctx))
150		return io_msg_data_remote(target_ctx, msg);
151
152	if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
153		flags = msg->cqe_flags;
154
155	ret = -EOVERFLOW;
156	if (target_ctx->flags & IORING_SETUP_IOPOLL) {
157		if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
158			return -EAGAIN;
159	}
160	if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
161		ret = 0;
162	if (target_ctx->flags & IORING_SETUP_IOPOLL)
163		io_double_unlock_ctx(target_ctx);
164	return ret;
165}
166
167static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
168{
169	struct io_ring_ctx *target_ctx = req->file->private_data;
170	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
171
172	return __io_msg_ring_data(target_ctx, msg, issue_flags);
173}
174
175static int io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
176{
177	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
178	struct io_ring_ctx *ctx = req->ctx;
179	struct io_rsrc_node *node;
180	int ret = -EBADF;
181
182	io_ring_submit_lock(ctx, issue_flags);
183	node = io_rsrc_node_lookup(&ctx->file_table.data, msg->src_fd);
184	if (node) {
185		msg->src_file = io_slot_file(node);
186		if (msg->src_file)
187			get_file(msg->src_file);
188		req->flags |= REQ_F_NEED_CLEANUP;
189		ret = 0;
190	}
191	io_ring_submit_unlock(ctx, issue_flags);
192	return ret;
193}
194
195static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
196{
197	struct io_ring_ctx *target_ctx = req->file->private_data;
198	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
199	struct file *src_file = msg->src_file;
200	int ret;
201
202	if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
203		return -EAGAIN;
204
205	ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
206	if (ret < 0)
207		goto out_unlock;
208
209	msg->src_file = NULL;
210	req->flags &= ~REQ_F_NEED_CLEANUP;
211
212	if (msg->flags & IORING_MSG_RING_CQE_SKIP)
213		goto out_unlock;
214	/*
215	 * If this fails, the target still received the file descriptor but
216	 * wasn't notified of the fact. This means that if this request
217	 * completes with -EOVERFLOW, then the sender must ensure that a
218	 * later IORING_OP_MSG_RING delivers the message.
219	 */
220	if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0))
221		ret = -EOVERFLOW;
222out_unlock:
223	io_double_unlock_ctx(target_ctx);
224	return ret;
225}
226
227static void io_msg_tw_fd_complete(struct callback_head *head)
228{
229	struct io_msg *msg = container_of(head, struct io_msg, tw);
230	struct io_kiocb *req = cmd_to_io_kiocb(msg);
231	int ret = -EOWNERDEAD;
232
233	if (!(current->flags & PF_EXITING))
234		ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED);
235	if (ret < 0)
236		req_set_fail(req);
237	io_req_queue_tw_complete(req, ret);
238}
239
240static int io_msg_fd_remote(struct io_kiocb *req)
241{
242	struct io_ring_ctx *ctx = req->file->private_data;
243	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
244	struct task_struct *task = READ_ONCE(ctx->submitter_task);
245
246	if (unlikely(!task))
247		return -EOWNERDEAD;
248
249	init_task_work(&msg->tw, io_msg_tw_fd_complete);
250	if (task_work_add(task, &msg->tw, TWA_SIGNAL))
251		return -EOWNERDEAD;
252
253	return IOU_ISSUE_SKIP_COMPLETE;
254}
255
256static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
257{
258	struct io_ring_ctx *target_ctx = req->file->private_data;
259	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
260	struct io_ring_ctx *ctx = req->ctx;
261
262	if (msg->len)
263		return -EINVAL;
264	if (target_ctx == ctx)
265		return -EINVAL;
266	if (target_ctx->flags & IORING_SETUP_R_DISABLED)
267		return -EBADFD;
268	if (!msg->src_file) {
269		int ret = io_msg_grab_file(req, issue_flags);
270		if (unlikely(ret))
271			return ret;
272	}
273
274	if (io_msg_need_remote(target_ctx))
275		return io_msg_fd_remote(req);
276	return io_msg_install_complete(req, issue_flags);
277}
278
279static int __io_msg_ring_prep(struct io_msg *msg, const struct io_uring_sqe *sqe)
280{
281	if (unlikely(sqe->buf_index || sqe->personality))
282		return -EINVAL;
283
284	msg->src_file = NULL;
285	msg->user_data = READ_ONCE(sqe->off);
286	msg->len = READ_ONCE(sqe->len);
287	msg->cmd = READ_ONCE(sqe->addr);
288	msg->src_fd = READ_ONCE(sqe->addr3);
289	msg->dst_fd = READ_ONCE(sqe->file_index);
290	msg->flags = READ_ONCE(sqe->msg_ring_flags);
291	if (msg->flags & ~IORING_MSG_RING_MASK)
292		return -EINVAL;
293
294	return 0;
295}
296
297int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
298{
299	return __io_msg_ring_prep(io_kiocb_to_cmd(req, struct io_msg), sqe);
300}
301
302int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
303{
304	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
305	int ret;
306
307	ret = -EBADFD;
308	if (!io_is_uring_fops(req->file))
309		goto done;
310
311	switch (msg->cmd) {
312	case IORING_MSG_DATA:
313		ret = io_msg_ring_data(req, issue_flags);
314		break;
315	case IORING_MSG_SEND_FD:
316		ret = io_msg_send_fd(req, issue_flags);
317		break;
318	default:
319		ret = -EINVAL;
320		break;
321	}
322
323done:
324	if (ret < 0) {
325		if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
326			return ret;
327		req_set_fail(req);
328	}
329	io_req_set_res(req, ret, 0);
330	return IOU_OK;
331}
332
333int io_uring_sync_msg_ring(struct io_uring_sqe *sqe)
334{
335	struct io_msg io_msg = { };
336	int ret;
337
338	ret = __io_msg_ring_prep(&io_msg, sqe);
339	if (unlikely(ret))
340		return ret;
341
342	/*
343	 * Only data sending supported, not IORING_MSG_SEND_FD as that one
344	 * doesn't make sense without a source ring to send files from.
345	 */
346	if (io_msg.cmd != IORING_MSG_DATA)
347		return -EINVAL;
348
349	CLASS(fd, f)(sqe->fd);
350	if (fd_empty(f))
351		return -EBADF;
352	if (!io_is_uring_fops(fd_file(f)))
353		return -EBADFD;
354	return  __io_msg_ring_data(fd_file(f)->private_data,
355				   &io_msg, IO_URING_F_UNLOCKED);
356}
357
358void io_msg_cache_free(const void *entry)
359{
360	struct io_kiocb *req = (struct io_kiocb *) entry;
361
362	kmem_cache_free(req_cachep, req);
363}