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36404b09 JA |
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> | |
e6130eba | 6 | #include <linux/nospec.h> |
36404b09 JA |
7 | #include <linux/io_uring.h> |
8 | ||
9 | #include <uapi/linux/io_uring.h> | |
10 | ||
36404b09 | 11 | #include "io_uring.h" |
e6130eba JA |
12 | #include "rsrc.h" |
13 | #include "filetable.h" | |
36404b09 JA |
14 | #include "msg_ring.h" |
15 | ||
16 | struct io_msg { | |
17 | struct file *file; | |
11373026 | 18 | struct file *src_file; |
6d043ee1 | 19 | struct callback_head tw; |
36404b09 JA |
20 | u64 user_data; |
21 | u32 len; | |
e6130eba JA |
22 | u32 cmd; |
23 | u32 src_fd; | |
24 | u32 dst_fd; | |
25 | u32 flags; | |
36404b09 JA |
26 | }; |
27 | ||
423d5081 JA |
28 | static void io_double_unlock_ctx(struct io_ring_ctx *octx) |
29 | { | |
30 | mutex_unlock(&octx->uring_lock); | |
31 | } | |
32 | ||
33 | static int io_double_lock_ctx(struct io_ring_ctx *octx, | |
34 | unsigned int issue_flags) | |
35 | { | |
36 | /* | |
37 | * To ensure proper ordering between the two ctxs, we can only | |
38 | * attempt a trylock on the target. If that fails and we already have | |
39 | * the source ctx lock, punt to io-wq. | |
40 | */ | |
41 | if (!(issue_flags & IO_URING_F_UNLOCKED)) { | |
42 | if (!mutex_trylock(&octx->uring_lock)) | |
43 | return -EAGAIN; | |
44 | return 0; | |
45 | } | |
46 | mutex_lock(&octx->uring_lock); | |
47 | return 0; | |
48 | } | |
49 | ||
11373026 PB |
50 | void io_msg_ring_cleanup(struct io_kiocb *req) |
51 | { | |
52 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); | |
53 | ||
54 | if (WARN_ON_ONCE(!msg->src_file)) | |
55 | return; | |
56 | ||
57 | fput(msg->src_file); | |
58 | msg->src_file = NULL; | |
59 | } | |
60 | ||
56d8e318 PB |
61 | static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx) |
62 | { | |
63 | if (!target_ctx->task_complete) | |
64 | return false; | |
65 | return current != target_ctx->submitter_task; | |
66 | } | |
67 | ||
68 | static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func) | |
69 | { | |
70 | struct io_ring_ctx *ctx = req->file->private_data; | |
71 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); | |
8579538c PB |
72 | struct task_struct *task = READ_ONCE(ctx->submitter_task); |
73 | ||
74 | if (unlikely(!task)) | |
75 | return -EOWNERDEAD; | |
56d8e318 PB |
76 | |
77 | init_task_work(&msg->tw, func); | |
78 | if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL)) | |
79 | return -EOWNERDEAD; | |
80 | ||
81 | return IOU_ISSUE_SKIP_COMPLETE; | |
82 | } | |
83 | ||
6d043ee1 PB |
84 | static void io_msg_tw_complete(struct callback_head *head) |
85 | { | |
86 | struct io_msg *msg = container_of(head, struct io_msg, tw); | |
87 | struct io_kiocb *req = cmd_to_io_kiocb(msg); | |
88 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
89 | int ret = 0; | |
90 | ||
e12d7a46 | 91 | if (current->flags & PF_EXITING) { |
6d043ee1 | 92 | ret = -EOWNERDEAD; |
e12d7a46 JA |
93 | } else { |
94 | /* | |
95 | * If the target ring is using IOPOLL mode, then we need to be | |
96 | * holding the uring_lock for posting completions. Other ring | |
97 | * types rely on the regular completion locking, which is | |
98 | * handled while posting. | |
99 | */ | |
100 | if (target_ctx->flags & IORING_SETUP_IOPOLL) | |
101 | mutex_lock(&target_ctx->uring_lock); | |
102 | if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) | |
103 | ret = -EOVERFLOW; | |
104 | if (target_ctx->flags & IORING_SETUP_IOPOLL) | |
105 | mutex_unlock(&target_ctx->uring_lock); | |
106 | } | |
6d043ee1 PB |
107 | |
108 | if (ret < 0) | |
109 | req_set_fail(req); | |
110 | io_req_queue_tw_complete(req, ret); | |
111 | } | |
112 | ||
e12d7a46 | 113 | static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) |
e6130eba JA |
114 | { |
115 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
f2ccb5ae | 116 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); |
e12d7a46 | 117 | int ret; |
e6130eba JA |
118 | |
119 | if (msg->src_fd || msg->dst_fd || msg->flags) | |
120 | return -EINVAL; | |
8579538c PB |
121 | if (target_ctx->flags & IORING_SETUP_R_DISABLED) |
122 | return -EBADFD; | |
e6130eba | 123 | |
56d8e318 PB |
124 | if (io_msg_need_remote(target_ctx)) |
125 | return io_msg_exec_remote(req, io_msg_tw_complete); | |
6d043ee1 | 126 | |
e12d7a46 JA |
127 | ret = -EOVERFLOW; |
128 | if (target_ctx->flags & IORING_SETUP_IOPOLL) { | |
129 | if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) | |
130 | return -EAGAIN; | |
131 | if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) | |
132 | ret = 0; | |
133 | io_double_unlock_ctx(target_ctx); | |
134 | } else { | |
135 | if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) | |
136 | ret = 0; | |
137 | } | |
138 | return ret; | |
e6130eba JA |
139 | } |
140 | ||
11373026 PB |
141 | static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags) |
142 | { | |
143 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); | |
144 | struct io_ring_ctx *ctx = req->ctx; | |
145 | struct file *file = NULL; | |
146 | unsigned long file_ptr; | |
147 | int idx = msg->src_fd; | |
148 | ||
149 | io_ring_submit_lock(ctx, issue_flags); | |
150 | if (likely(idx < ctx->nr_user_files)) { | |
151 | idx = array_index_nospec(idx, ctx->nr_user_files); | |
152 | file_ptr = io_fixed_file_slot(&ctx->file_table, idx)->file_ptr; | |
153 | file = (struct file *) (file_ptr & FFS_MASK); | |
154 | if (file) | |
155 | get_file(file); | |
e6130eba | 156 | } |
11373026 PB |
157 | io_ring_submit_unlock(ctx, issue_flags); |
158 | return file; | |
e6130eba JA |
159 | } |
160 | ||
17211310 | 161 | static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags) |
e6130eba JA |
162 | { |
163 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
f2ccb5ae | 164 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); |
11373026 | 165 | struct file *src_file = msg->src_file; |
e6130eba JA |
166 | int ret; |
167 | ||
11373026 PB |
168 | if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) |
169 | return -EAGAIN; | |
e6130eba JA |
170 | |
171 | ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd); | |
11373026 | 172 | if (ret < 0) |
e6130eba | 173 | goto out_unlock; |
17211310 | 174 | |
11373026 PB |
175 | msg->src_file = NULL; |
176 | req->flags &= ~REQ_F_NEED_CLEANUP; | |
e6130eba JA |
177 | |
178 | if (msg->flags & IORING_MSG_RING_CQE_SKIP) | |
179 | goto out_unlock; | |
e6130eba JA |
180 | /* |
181 | * If this fails, the target still received the file descriptor but | |
182 | * wasn't notified of the fact. This means that if this request | |
183 | * completes with -EOVERFLOW, then the sender must ensure that a | |
184 | * later IORING_OP_MSG_RING delivers the message. | |
185 | */ | |
b529c96a | 186 | if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) |
e6130eba JA |
187 | ret = -EOVERFLOW; |
188 | out_unlock: | |
423d5081 | 189 | io_double_unlock_ctx(target_ctx); |
e6130eba JA |
190 | return ret; |
191 | } | |
192 | ||
6d043ee1 PB |
193 | static void io_msg_tw_fd_complete(struct callback_head *head) |
194 | { | |
195 | struct io_msg *msg = container_of(head, struct io_msg, tw); | |
196 | struct io_kiocb *req = cmd_to_io_kiocb(msg); | |
197 | int ret = -EOWNERDEAD; | |
198 | ||
199 | if (!(current->flags & PF_EXITING)) | |
200 | ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED); | |
201 | if (ret < 0) | |
202 | req_set_fail(req); | |
203 | io_req_queue_tw_complete(req, ret); | |
204 | } | |
205 | ||
17211310 PB |
206 | static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags) |
207 | { | |
208 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
209 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); | |
210 | struct io_ring_ctx *ctx = req->ctx; | |
211 | struct file *src_file = msg->src_file; | |
212 | ||
213 | if (target_ctx == ctx) | |
214 | return -EINVAL; | |
8579538c PB |
215 | if (target_ctx->flags & IORING_SETUP_R_DISABLED) |
216 | return -EBADFD; | |
17211310 PB |
217 | if (!src_file) { |
218 | src_file = io_msg_grab_file(req, issue_flags); | |
219 | if (!src_file) | |
220 | return -EBADF; | |
221 | msg->src_file = src_file; | |
222 | req->flags |= REQ_F_NEED_CLEANUP; | |
223 | } | |
6d043ee1 | 224 | |
56d8e318 PB |
225 | if (io_msg_need_remote(target_ctx)) |
226 | return io_msg_exec_remote(req, io_msg_tw_fd_complete); | |
17211310 PB |
227 | return io_msg_install_complete(req, issue_flags); |
228 | } | |
229 | ||
36404b09 JA |
230 | int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) |
231 | { | |
f2ccb5ae | 232 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); |
36404b09 | 233 | |
e6130eba | 234 | if (unlikely(sqe->buf_index || sqe->personality)) |
36404b09 JA |
235 | return -EINVAL; |
236 | ||
11373026 | 237 | msg->src_file = NULL; |
36404b09 JA |
238 | msg->user_data = READ_ONCE(sqe->off); |
239 | msg->len = READ_ONCE(sqe->len); | |
e6130eba JA |
240 | msg->cmd = READ_ONCE(sqe->addr); |
241 | msg->src_fd = READ_ONCE(sqe->addr3); | |
242 | msg->dst_fd = READ_ONCE(sqe->file_index); | |
243 | msg->flags = READ_ONCE(sqe->msg_ring_flags); | |
244 | if (msg->flags & ~IORING_MSG_RING_CQE_SKIP) | |
245 | return -EINVAL; | |
246 | ||
36404b09 JA |
247 | return 0; |
248 | } | |
249 | ||
250 | int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) | |
251 | { | |
f2ccb5ae | 252 | struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); |
36404b09 JA |
253 | int ret; |
254 | ||
255 | ret = -EBADFD; | |
256 | if (!io_is_uring_fops(req->file)) | |
257 | goto done; | |
258 | ||
e6130eba JA |
259 | switch (msg->cmd) { |
260 | case IORING_MSG_DATA: | |
e12d7a46 | 261 | ret = io_msg_ring_data(req, issue_flags); |
e6130eba JA |
262 | break; |
263 | case IORING_MSG_SEND_FD: | |
264 | ret = io_msg_send_fd(req, issue_flags); | |
265 | break; | |
266 | default: | |
267 | ret = -EINVAL; | |
268 | break; | |
269 | } | |
36404b09 JA |
270 | |
271 | done: | |
6d043ee1 PB |
272 | if (ret < 0) { |
273 | if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE) | |
274 | return ret; | |
36404b09 | 275 | req_set_fail(req); |
6d043ee1 | 276 | } |
36404b09 | 277 | io_req_set_res(req, ret, 0); |
36404b09 JA |
278 | return IOU_OK; |
279 | } |