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/* All valid masks for MSG_RING */
17#define IORING_MSG_RING_MASK (IORING_MSG_RING_CQE_SKIP | \
18 IORING_MSG_RING_FLAGS_PASS)
19
20struct io_msg {
21 struct file *file;
22 struct file *src_file;
23 struct callback_head tw;
24 u64 user_data;
25 u32 len;
26 u32 cmd;
27 u32 src_fd;
28 union {
29 u32 dst_fd;
30 u32 cqe_flags;
31 };
32 u32 flags;
33};
34
35static void io_double_unlock_ctx(struct io_ring_ctx *octx)
36{
37 mutex_unlock(lock: &octx->uring_lock);
38}
39
40static int io_lock_external_ctx(struct io_ring_ctx *octx,
41 unsigned int issue_flags)
42{
43 /*
44 * To ensure proper ordering between the two ctxs, we can only
45 * attempt a trylock on the target. If that fails and we already have
46 * the source ctx lock, punt to io-wq.
47 */
48 if (!(issue_flags & IO_URING_F_UNLOCKED)) {
49 if (!mutex_trylock(lock: &octx->uring_lock))
50 return -EAGAIN;
51 return 0;
52 }
53 mutex_lock(lock: &octx->uring_lock);
54 return 0;
55}
56
57void io_msg_ring_cleanup(struct io_kiocb *req)
58{
59 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
60
61 if (WARN_ON_ONCE(!msg->src_file))
62 return;
63
64 fput(msg->src_file);
65 msg->src_file = NULL;
66}
67
68static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx)
69{
70 return target_ctx->task_complete;
71}
72
73static void io_msg_tw_complete(struct io_kiocb *req, io_tw_token_t tw)
74{
75 struct io_ring_ctx *ctx = req->ctx;
76
77 io_add_aux_cqe(ctx, user_data: req->cqe.user_data, res: req->cqe.res, cflags: req->cqe.flags);
78 kfree_rcu(req, rcu_head);
79 percpu_ref_put(ref: &ctx->refs);
80}
81
82static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req,
83 int res, u32 cflags, u64 user_data)
84{
85 if (!READ_ONCE(ctx->submitter_task)) {
86 kfree_rcu(req, rcu_head);
87 return -EOWNERDEAD;
88 }
89 req->opcode = IORING_OP_NOP;
90 req->cqe.user_data = user_data;
91 io_req_set_res(req, res, cflags);
92 percpu_ref_get(ref: &ctx->refs);
93 req->ctx = ctx;
94 req->tctx = NULL;
95 req->io_task_work.func = io_msg_tw_complete;
96 io_req_task_work_add_remote(req, flags: IOU_F_TWQ_LAZY_WAKE);
97 return 0;
98}
99
100static int io_msg_data_remote(struct io_ring_ctx *target_ctx,
101 struct io_msg *msg)
102{
103 struct io_kiocb *target;
104 u32 flags = 0;
105
106 target = kmem_cache_alloc(req_cachep, GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO) ;
107 if (unlikely(!target))
108 return -ENOMEM;
109
110 if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
111 flags = msg->cqe_flags;
112
113 return io_msg_remote_post(ctx: target_ctx, req: target, res: msg->len, cflags: flags,
114 user_data: msg->user_data);
115}
116
117static int __io_msg_ring_data(struct io_ring_ctx *target_ctx,
118 struct io_msg *msg, unsigned int issue_flags)
119{
120 u32 flags = 0;
121 int ret;
122
123 if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
124 return -EINVAL;
125 if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
126 return -EINVAL;
127 if (target_ctx->flags & IORING_SETUP_R_DISABLED)
128 return -EBADFD;
129
130 if (io_msg_need_remote(target_ctx))
131 return io_msg_data_remote(target_ctx, msg);
132
133 if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
134 flags = msg->cqe_flags;
135
136 ret = -EOVERFLOW;
137 if (target_ctx->flags & IORING_SETUP_IOPOLL) {
138 if (unlikely(io_lock_external_ctx(target_ctx, issue_flags)))
139 return -EAGAIN;
140 }
141 if (io_post_aux_cqe(ctx: target_ctx, user_data: msg->user_data, res: msg->len, cflags: flags))
142 ret = 0;
143 if (target_ctx->flags & IORING_SETUP_IOPOLL)
144 io_double_unlock_ctx(octx: target_ctx);
145 return ret;
146}
147
148static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
149{
150 struct io_ring_ctx *target_ctx = req->file->private_data;
151 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
152
153 return __io_msg_ring_data(target_ctx, msg, issue_flags);
154}
155
156static int io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
157{
158 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
159 struct io_ring_ctx *ctx = req->ctx;
160 struct io_rsrc_node *node;
161 int ret = -EBADF;
162
163 io_ring_submit_lock(ctx, issue_flags);
164 node = io_rsrc_node_lookup(data: &ctx->file_table.data, index: msg->src_fd);
165 if (node) {
166 msg->src_file = io_slot_file(node);
167 if (msg->src_file)
168 get_file(f: msg->src_file);
169 req->flags |= REQ_F_NEED_CLEANUP;
170 ret = 0;
171 }
172 io_ring_submit_unlock(ctx, issue_flags);
173 return ret;
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_lock_external_ctx(target_ctx, issue_flags)))
184 return -EAGAIN;
185
186 ret = __io_fixed_fd_install(ctx: target_ctx, file: src_file, file_slot: 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(ctx: target_ctx, user_data: msg->user_data, res: ret, cflags: 0))
202 ret = -EOVERFLOW;
203out_unlock:
204 io_double_unlock_ctx(octx: 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(ptr: msg);
212 int ret = -EOWNERDEAD;
213
214 if (!(current->flags & PF_EXITING))
215 ret = io_msg_install_complete(req, issue_flags: IO_URING_F_UNLOCKED);
216 if (ret < 0)
217 req_set_fail(req);
218 io_req_queue_tw_complete(req, res: ret);
219}
220
221static int io_msg_fd_remote(struct io_kiocb *req)
222{
223 struct io_ring_ctx *ctx = req->file->private_data;
224 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
225 struct task_struct *task = READ_ONCE(ctx->submitter_task);
226
227 if (unlikely(!task))
228 return -EOWNERDEAD;
229
230 init_task_work(twork: &msg->tw, func: io_msg_tw_fd_complete);
231 if (task_work_add(task, twork: &msg->tw, mode: TWA_SIGNAL))
232 return -EOWNERDEAD;
233
234 return IOU_ISSUE_SKIP_COMPLETE;
235}
236
237static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
238{
239 struct io_ring_ctx *target_ctx = req->file->private_data;
240 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
241 struct io_ring_ctx *ctx = req->ctx;
242
243 if (msg->len)
244 return -EINVAL;
245 if (target_ctx == ctx)
246 return -EINVAL;
247 if (target_ctx->flags & IORING_SETUP_R_DISABLED)
248 return -EBADFD;
249 if (!msg->src_file) {
250 int ret = io_msg_grab_file(req, issue_flags);
251 if (unlikely(ret))
252 return ret;
253 }
254
255 if (io_msg_need_remote(target_ctx))
256 return io_msg_fd_remote(req);
257 return io_msg_install_complete(req, issue_flags);
258}
259
260static int __io_msg_ring_prep(struct io_msg *msg, const struct io_uring_sqe *sqe)
261{
262 if (unlikely(sqe->buf_index || sqe->personality))
263 return -EINVAL;
264
265 msg->src_file = NULL;
266 msg->user_data = READ_ONCE(sqe->off);
267 msg->len = READ_ONCE(sqe->len);
268 msg->cmd = READ_ONCE(sqe->addr);
269 msg->src_fd = READ_ONCE(sqe->addr3);
270 msg->dst_fd = READ_ONCE(sqe->file_index);
271 msg->flags = READ_ONCE(sqe->msg_ring_flags);
272 if (msg->flags & ~IORING_MSG_RING_MASK)
273 return -EINVAL;
274
275 return 0;
276}
277
278int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
279{
280 return __io_msg_ring_prep(io_kiocb_to_cmd(req, struct io_msg), sqe);
281}
282
283int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
284{
285 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
286 int ret;
287
288 ret = -EBADFD;
289 if (!io_is_uring_fops(file: req->file))
290 goto done;
291
292 switch (msg->cmd) {
293 case IORING_MSG_DATA:
294 ret = io_msg_ring_data(req, issue_flags);
295 break;
296 case IORING_MSG_SEND_FD:
297 ret = io_msg_send_fd(req, issue_flags);
298 break;
299 default:
300 ret = -EINVAL;
301 break;
302 }
303
304done:
305 if (ret < 0) {
306 if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
307 return ret;
308 req_set_fail(req);
309 }
310 io_req_set_res(req, res: ret, cflags: 0);
311 return IOU_COMPLETE;
312}
313
314int io_uring_sync_msg_ring(struct io_uring_sqe *sqe)
315{
316 struct io_msg io_msg = { };
317 int ret;
318
319 ret = __io_msg_ring_prep(msg: &io_msg, sqe);
320 if (unlikely(ret))
321 return ret;
322
323 /*
324 * Only data sending supported, not IORING_MSG_SEND_FD as that one
325 * doesn't make sense without a source ring to send files from.
326 */
327 if (io_msg.cmd != IORING_MSG_DATA)
328 return -EINVAL;
329
330 CLASS(fd, f)(fd: sqe->fd);
331 if (fd_empty(f))
332 return -EBADF;
333 if (!io_is_uring_fops(fd_file(f)))
334 return -EBADFD;
335 return __io_msg_ring_data(fd_file(f)->private_data,
336 msg: &io_msg, issue_flags: IO_URING_F_UNLOCKED);
337}
338