Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
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 "msg_ring.h"
15
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 if (!target_ctx->task_complete)
72 return false;
73 return current != target_ctx->submitter_task;
74}
75
76static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func)
77{
78 struct io_ring_ctx *ctx = req->file->private_data;
79 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
80 struct task_struct *task = READ_ONCE(ctx->submitter_task);
81
82 if (unlikely(!task))
83 return -EOWNERDEAD;
84
85 init_task_work(&msg->tw, func);
86 if (task_work_add(task, &msg->tw, TWA_SIGNAL))
87 return -EOWNERDEAD;
88
89 return IOU_ISSUE_SKIP_COMPLETE;
90}
91
92static void io_msg_tw_complete(struct callback_head *head)
93{
94 struct io_msg *msg = container_of(head, struct io_msg, tw);
95 struct io_kiocb *req = cmd_to_io_kiocb(msg);
96 struct io_ring_ctx *target_ctx = req->file->private_data;
97 int ret = 0;
98
99 if (current->flags & PF_EXITING) {
100 ret = -EOWNERDEAD;
101 } else {
102 u32 flags = 0;
103
104 if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
105 flags = msg->cqe_flags;
106
107 /*
108 * If the target ring is using IOPOLL mode, then we need to be
109 * holding the uring_lock for posting completions. Other ring
110 * types rely on the regular completion locking, which is
111 * handled while posting.
112 */
113 if (target_ctx->flags & IORING_SETUP_IOPOLL)
114 mutex_lock(&target_ctx->uring_lock);
115 if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
116 ret = -EOVERFLOW;
117 if (target_ctx->flags & IORING_SETUP_IOPOLL)
118 mutex_unlock(&target_ctx->uring_lock);
119 }
120
121 if (ret < 0)
122 req_set_fail(req);
123 io_req_queue_tw_complete(req, ret);
124}
125
126static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
127{
128 struct io_ring_ctx *target_ctx = req->file->private_data;
129 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
130 u32 flags = 0;
131 int ret;
132
133 if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
134 return -EINVAL;
135 if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
136 return -EINVAL;
137 if (target_ctx->flags & IORING_SETUP_R_DISABLED)
138 return -EBADFD;
139
140 if (io_msg_need_remote(target_ctx))
141 return io_msg_exec_remote(req, io_msg_tw_complete);
142
143 if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
144 flags = msg->cqe_flags;
145
146 ret = -EOVERFLOW;
147 if (target_ctx->flags & IORING_SETUP_IOPOLL) {
148 if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
149 return -EAGAIN;
150 }
151 if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
152 ret = 0;
153 if (target_ctx->flags & IORING_SETUP_IOPOLL)
154 io_double_unlock_ctx(target_ctx);
155 return ret;
156}
157
158static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
159{
160 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
161 struct io_ring_ctx *ctx = req->ctx;
162 struct file *file = NULL;
163 int idx = msg->src_fd;
164
165 io_ring_submit_lock(ctx, issue_flags);
166 if (likely(idx < ctx->nr_user_files)) {
167 idx = array_index_nospec(idx, ctx->nr_user_files);
168 file = io_file_from_index(&ctx->file_table, idx);
169 if (file)
170 get_file(file);
171 }
172 io_ring_submit_unlock(ctx, issue_flags);
173 return file;
174}
175
176static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
177{
178 struct io_ring_ctx *target_ctx = req->file->private_data;
179 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
180 struct file *src_file = msg->src_file;
181 int ret;
182
183 if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
184 return -EAGAIN;
185
186 ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
187 if (ret < 0)
188 goto out_unlock;
189
190 msg->src_file = NULL;
191 req->flags &= ~REQ_F_NEED_CLEANUP;
192
193 if (msg->flags & IORING_MSG_RING_CQE_SKIP)
194 goto out_unlock;
195 /*
196 * If this fails, the target still received the file descriptor but
197 * wasn't notified of the fact. This means that if this request
198 * completes with -EOVERFLOW, then the sender must ensure that a
199 * later IORING_OP_MSG_RING delivers the message.
200 */
201 if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0))
202 ret = -EOVERFLOW;
203out_unlock:
204 io_double_unlock_ctx(target_ctx);
205 return ret;
206}
207
208static void io_msg_tw_fd_complete(struct callback_head *head)
209{
210 struct io_msg *msg = container_of(head, struct io_msg, tw);
211 struct io_kiocb *req = cmd_to_io_kiocb(msg);
212 int ret = -EOWNERDEAD;
213
214 if (!(current->flags & PF_EXITING))
215 ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED);
216 if (ret < 0)
217 req_set_fail(req);
218 io_req_queue_tw_complete(req, ret);
219}
220
221static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
222{
223 struct io_ring_ctx *target_ctx = req->file->private_data;
224 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
225 struct io_ring_ctx *ctx = req->ctx;
226 struct file *src_file = msg->src_file;
227
228 if (msg->len)
229 return -EINVAL;
230 if (target_ctx == ctx)
231 return -EINVAL;
232 if (target_ctx->flags & IORING_SETUP_R_DISABLED)
233 return -EBADFD;
234 if (!src_file) {
235 src_file = io_msg_grab_file(req, issue_flags);
236 if (!src_file)
237 return -EBADF;
238 msg->src_file = src_file;
239 req->flags |= REQ_F_NEED_CLEANUP;
240 }
241
242 if (io_msg_need_remote(target_ctx))
243 return io_msg_exec_remote(req, io_msg_tw_fd_complete);
244 return io_msg_install_complete(req, issue_flags);
245}
246
247int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
248{
249 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
250
251 if (unlikely(sqe->buf_index || sqe->personality))
252 return -EINVAL;
253
254 msg->src_file = NULL;
255 msg->user_data = READ_ONCE(sqe->off);
256 msg->len = READ_ONCE(sqe->len);
257 msg->cmd = READ_ONCE(sqe->addr);
258 msg->src_fd = READ_ONCE(sqe->addr3);
259 msg->dst_fd = READ_ONCE(sqe->file_index);
260 msg->flags = READ_ONCE(sqe->msg_ring_flags);
261 if (msg->flags & ~IORING_MSG_RING_MASK)
262 return -EINVAL;
263
264 return 0;
265}
266
267int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
268{
269 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
270 int ret;
271
272 ret = -EBADFD;
273 if (!io_is_uring_fops(req->file))
274 goto done;
275
276 switch (msg->cmd) {
277 case IORING_MSG_DATA:
278 ret = io_msg_ring_data(req, issue_flags);
279 break;
280 case IORING_MSG_SEND_FD:
281 ret = io_msg_send_fd(req, issue_flags);
282 break;
283 default:
284 ret = -EINVAL;
285 break;
286 }
287
288done:
289 if (ret < 0) {
290 if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
291 return ret;
292 req_set_fail(req);
293 }
294 io_req_set_res(req, ret, 0);
295 return IOU_OK;
296}