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/mm.h>
6 #include <linux/slab.h>
7 #include <linux/nospec.h>
8 #include <linux/io_uring.h>
9
10 #include <uapi/linux/io_uring.h>
11
12 #include "io_uring.h"
13 #include "tctx.h"
14
15 static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
16 struct task_struct *task)
17 {
18 struct io_wq_hash *hash;
19 struct io_wq_data data;
20 unsigned int concurrency;
21
22 mutex_lock(&ctx->uring_lock);
23 hash = ctx->hash_map;
24 if (!hash) {
25 hash = kzalloc(sizeof(*hash), GFP_KERNEL);
26 if (!hash) {
27 mutex_unlock(&ctx->uring_lock);
28 return ERR_PTR(-ENOMEM);
29 }
30 refcount_set(&hash->refs, 1);
31 init_waitqueue_head(&hash->wait);
32 ctx->hash_map = hash;
33 }
34 mutex_unlock(&ctx->uring_lock);
35
36 data.hash = hash;
37 data.task = task;
38 data.free_work = io_wq_free_work;
39 data.do_work = io_wq_submit_work;
40
41 /* Do QD, or 4 * CPUS, whatever is smallest */
42 concurrency = min(ctx->sq_entries, 4 * num_online_cpus());
43
44 return io_wq_create(concurrency, &data);
45 }
46
47 void __io_uring_free(struct task_struct *tsk)
48 {
49 struct io_uring_task *tctx = tsk->io_uring;
50
51 WARN_ON_ONCE(!xa_empty(&tctx->xa));
52 WARN_ON_ONCE(tctx->io_wq);
53 WARN_ON_ONCE(tctx->cached_refs);
54
55 percpu_counter_destroy(&tctx->inflight);
56 kfree(tctx);
57 tsk->io_uring = NULL;
58 }
59
60 __cold int io_uring_alloc_task_context(struct task_struct *task,
61 struct io_ring_ctx *ctx)
62 {
63 struct io_uring_task *tctx;
64 int ret;
65
66 tctx = kzalloc(sizeof(*tctx), GFP_KERNEL);
67 if (unlikely(!tctx))
68 return -ENOMEM;
69
70 ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
71 if (unlikely(ret)) {
72 kfree(tctx);
73 return ret;
74 }
75
76 tctx->io_wq = io_init_wq_offload(ctx, task);
77 if (IS_ERR(tctx->io_wq)) {
78 ret = PTR_ERR(tctx->io_wq);
79 percpu_counter_destroy(&tctx->inflight);
80 kfree(tctx);
81 return ret;
82 }
83
84 xa_init(&tctx->xa);
85 init_waitqueue_head(&tctx->wait);
86 atomic_set(&tctx->in_cancel, 0);
87 atomic_set(&tctx->inflight_tracked, 0);
88 task->io_uring = tctx;
89 init_llist_head(&tctx->task_list);
90 init_task_work(&tctx->task_work, tctx_task_work);
91 return 0;
92 }
93
94 int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
95 {
96 struct io_uring_task *tctx = current->io_uring;
97 struct io_tctx_node *node;
98 int ret;
99
100 if (unlikely(!tctx)) {
101 ret = io_uring_alloc_task_context(current, ctx);
102 if (unlikely(ret))
103 return ret;
104
105 tctx = current->io_uring;
106 if (ctx->iowq_limits_set) {
107 unsigned int limits[2] = { ctx->iowq_limits[0],
108 ctx->iowq_limits[1], };
109
110 ret = io_wq_max_workers(tctx->io_wq, limits);
111 if (ret)
112 return ret;
113 }
114 }
115 if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
116 node = kmalloc(sizeof(*node), GFP_KERNEL);
117 if (!node)
118 return -ENOMEM;
119 node->ctx = ctx;
120 node->task = current;
121
122 ret = xa_err(xa_store(&tctx->xa, (unsigned long)ctx,
123 node, GFP_KERNEL));
124 if (ret) {
125 kfree(node);
126 return ret;
127 }
128
129 mutex_lock(&ctx->uring_lock);
130 list_add(&node->ctx_node, &ctx->tctx_list);
131 mutex_unlock(&ctx->uring_lock);
132 }
133 return 0;
134 }
135
136 int __io_uring_add_tctx_node_from_submit(struct io_ring_ctx *ctx)
137 {
138 int ret;
139
140 if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
141 && ctx->submitter_task != current)
142 return -EEXIST;
143
144 ret = __io_uring_add_tctx_node(ctx);
145 if (ret)
146 return ret;
147
148 current->io_uring->last = ctx;
149 return 0;
150 }
151
152 /*
153 * Remove this io_uring_file -> task mapping.
154 */
155 __cold void io_uring_del_tctx_node(unsigned long index)
156 {
157 struct io_uring_task *tctx = current->io_uring;
158 struct io_tctx_node *node;
159
160 if (!tctx)
161 return;
162 node = xa_erase(&tctx->xa, index);
163 if (!node)
164 return;
165
166 WARN_ON_ONCE(current != node->task);
167 WARN_ON_ONCE(list_empty(&node->ctx_node));
168
169 mutex_lock(&node->ctx->uring_lock);
170 list_del(&node->ctx_node);
171 mutex_unlock(&node->ctx->uring_lock);
172
173 if (tctx->last == node->ctx)
174 tctx->last = NULL;
175 kfree(node);
176 }
177
178 __cold void io_uring_clean_tctx(struct io_uring_task *tctx)
179 {
180 struct io_wq *wq = tctx->io_wq;
181 struct io_tctx_node *node;
182 unsigned long index;
183
184 xa_for_each(&tctx->xa, index, node) {
185 io_uring_del_tctx_node(index);
186 cond_resched();
187 }
188 if (wq) {
189 /*
190 * Must be after io_uring_del_tctx_node() (removes nodes under
191 * uring_lock) to avoid race with io_uring_try_cancel_iowq().
192 */
193 io_wq_put_and_exit(wq);
194 tctx->io_wq = NULL;
195 }
196 }
197
198 void io_uring_unreg_ringfd(void)
199 {
200 struct io_uring_task *tctx = current->io_uring;
201 int i;
202
203 for (i = 0; i < IO_RINGFD_REG_MAX; i++) {
204 if (tctx->registered_rings[i]) {
205 fput(tctx->registered_rings[i]);
206 tctx->registered_rings[i] = NULL;
207 }
208 }
209 }
210
211 int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,
212 int start, int end)
213 {
214 int offset;
215 for (offset = start; offset < end; offset++) {
216 offset = array_index_nospec(offset, IO_RINGFD_REG_MAX);
217 if (tctx->registered_rings[offset])
218 continue;
219
220 tctx->registered_rings[offset] = file;
221 return offset;
222 }
223 return -EBUSY;
224 }
225
226 static int io_ring_add_registered_fd(struct io_uring_task *tctx, int fd,
227 int start, int end)
228 {
229 struct file *file;
230 int offset;
231
232 file = fget(fd);
233 if (!file) {
234 return -EBADF;
235 } else if (!io_is_uring_fops(file)) {
236 fput(file);
237 return -EOPNOTSUPP;
238 }
239 offset = io_ring_add_registered_file(tctx, file, start, end);
240 if (offset < 0)
241 fput(file);
242 return offset;
243 }
244
245 /*
246 * Register a ring fd to avoid fdget/fdput for each io_uring_enter()
247 * invocation. User passes in an array of struct io_uring_rsrc_update
248 * with ->data set to the ring_fd, and ->offset given for the desired
249 * index. If no index is desired, application may set ->offset == -1U
250 * and we'll find an available index. Returns number of entries
251 * successfully processed, or < 0 on error if none were processed.
252 */
253 int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg,
254 unsigned nr_args)
255 {
256 struct io_uring_rsrc_update __user *arg = __arg;
257 struct io_uring_rsrc_update reg;
258 struct io_uring_task *tctx;
259 int ret, i;
260
261 if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
262 return -EINVAL;
263
264 mutex_unlock(&ctx->uring_lock);
265 ret = __io_uring_add_tctx_node(ctx);
266 mutex_lock(&ctx->uring_lock);
267 if (ret)
268 return ret;
269
270 tctx = current->io_uring;
271 for (i = 0; i < nr_args; i++) {
272 int start, end;
273
274 if (copy_from_user(®, &arg[i], sizeof(reg))) {
275 ret = -EFAULT;
276 break;
277 }
278
279 if (reg.resv) {
280 ret = -EINVAL;
281 break;
282 }
283
284 if (reg.offset == -1U) {
285 start = 0;
286 end = IO_RINGFD_REG_MAX;
287 } else {
288 if (reg.offset >= IO_RINGFD_REG_MAX) {
289 ret = -EINVAL;
290 break;
291 }
292 start = reg.offset;
293 end = start + 1;
294 }
295
296 ret = io_ring_add_registered_fd(tctx, reg.data, start, end);
297 if (ret < 0)
298 break;
299
300 reg.offset = ret;
301 if (copy_to_user(&arg[i], ®, sizeof(reg))) {
302 fput(tctx->registered_rings[reg.offset]);
303 tctx->registered_rings[reg.offset] = NULL;
304 ret = -EFAULT;
305 break;
306 }
307 }
308
309 return i ? i : ret;
310 }
311
312 int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
313 unsigned nr_args)
314 {
315 struct io_uring_rsrc_update __user *arg = __arg;
316 struct io_uring_task *tctx = current->io_uring;
317 struct io_uring_rsrc_update reg;
318 int ret = 0, i;
319
320 if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
321 return -EINVAL;
322 if (!tctx)
323 return 0;
324
325 for (i = 0; i < nr_args; i++) {
326 if (copy_from_user(®, &arg[i], sizeof(reg))) {
327 ret = -EFAULT;
328 break;
329 }
330 if (reg.resv || reg.data || reg.offset >= IO_RINGFD_REG_MAX) {
331 ret = -EINVAL;
332 break;
333 }
334
335 reg.offset = array_index_nospec(reg.offset, IO_RINGFD_REG_MAX);
336 if (tctx->registered_rings[reg.offset]) {
337 fput(tctx->registered_rings[reg.offset]);
338 tctx->registered_rings[reg.offset] = NULL;
339 }
340 }
341
342 return i ? i : ret;
343 }
344
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.