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 21 struct 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 36 static void io_double_unlock_ctx(struct io_ring_ctx *octx) 37 { 38 mutex_unlock(&octx->uring_lock); 39 } 40 41 static 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 58 void 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 69 static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx) 70 { 71 return target_ctx->task_complete; 72 } 73 74 static 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 89 static int io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req, 90 int res, u32 cflags, u64 user_data) 91 { 92 req->task = READ_ONCE(ctx->submitter_task); 93 if (!req->task) { 94 kmem_cache_free(req_cachep, req); 95 return -EOWNERDEAD; 96 } 97 req->cqe.user_data = user_data; 98 io_req_set_res(req, res, cflags); 99 percpu_ref_get(&ctx->refs); 100 req->ctx = ctx; 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 } 105 106 static 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 } 118 119 static int io_msg_data_remote(struct io_kiocb *req) 120 { 121 struct io_ring_ctx *target_ctx = req->file->private_data; 122 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 123 struct io_kiocb *target; 124 u32 flags = 0; 125 126 target = io_msg_get_kiocb(req->ctx); 127 if (unlikely(!target)) 128 return -ENOMEM; 129 130 if (msg->flags & IORING_MSG_RING_FLAGS_PASS) 131 flags = msg->cqe_flags; 132 133 return io_msg_remote_post(target_ctx, target, msg->len, flags, 134 msg->user_data); 135 } 136 137 static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) 138 { 139 struct io_ring_ctx *target_ctx = req->file->private_data; 140 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 141 u32 flags = 0; 142 int ret; 143 144 if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS) 145 return -EINVAL; 146 if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd) 147 return -EINVAL; 148 if (target_ctx->flags & IORING_SETUP_R_DISABLED) 149 return -EBADFD; 150 151 if (io_msg_need_remote(target_ctx)) 152 return io_msg_data_remote(req); 153 154 if (msg->flags & IORING_MSG_RING_FLAGS_PASS) 155 flags = msg->cqe_flags; 156 157 ret = -EOVERFLOW; 158 if (target_ctx->flags & IORING_SETUP_IOPOLL) { 159 if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) 160 return -EAGAIN; 161 } 162 if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags)) 163 ret = 0; 164 if (target_ctx->flags & IORING_SETUP_IOPOLL) 165 io_double_unlock_ctx(target_ctx); 166 return ret; 167 } 168 169 static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags) 170 { 171 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 172 struct io_ring_ctx *ctx = req->ctx; 173 struct file *file = NULL; 174 int idx = msg->src_fd; 175 176 io_ring_submit_lock(ctx, issue_flags); 177 if (likely(idx < ctx->nr_user_files)) { 178 idx = array_index_nospec(idx, ctx->nr_user_files); 179 file = io_file_from_index(&ctx->file_table, idx); 180 if (file) 181 get_file(file); 182 } 183 io_ring_submit_unlock(ctx, issue_flags); 184 return file; 185 } 186 187 static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags) 188 { 189 struct io_ring_ctx *target_ctx = req->file->private_data; 190 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 191 struct file *src_file = msg->src_file; 192 int ret; 193 194 if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) 195 return -EAGAIN; 196 197 ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd); 198 if (ret < 0) 199 goto out_unlock; 200 201 msg->src_file = NULL; 202 req->flags &= ~REQ_F_NEED_CLEANUP; 203 204 if (msg->flags & IORING_MSG_RING_CQE_SKIP) 205 goto out_unlock; 206 /* 207 * If this fails, the target still received the file descriptor but 208 * wasn't notified of the fact. This means that if this request 209 * completes with -EOVERFLOW, then the sender must ensure that a 210 * later IORING_OP_MSG_RING delivers the message. 211 */ 212 if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0)) 213 ret = -EOVERFLOW; 214 out_unlock: 215 io_double_unlock_ctx(target_ctx); 216 return ret; 217 } 218 219 static void io_msg_tw_fd_complete(struct callback_head *head) 220 { 221 struct io_msg *msg = container_of(head, struct io_msg, tw); 222 struct io_kiocb *req = cmd_to_io_kiocb(msg); 223 int ret = -EOWNERDEAD; 224 225 if (!(current->flags & PF_EXITING)) 226 ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED); 227 if (ret < 0) 228 req_set_fail(req); 229 io_req_queue_tw_complete(req, ret); 230 } 231 232 static int io_msg_fd_remote(struct io_kiocb *req) 233 { 234 struct io_ring_ctx *ctx = req->file->private_data; 235 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 236 struct task_struct *task = READ_ONCE(ctx->submitter_task); 237 238 if (unlikely(!task)) 239 return -EOWNERDEAD; 240 241 init_task_work(&msg->tw, io_msg_tw_fd_complete); 242 if (task_work_add(task, &msg->tw, TWA_SIGNAL)) 243 return -EOWNERDEAD; 244 245 return IOU_ISSUE_SKIP_COMPLETE; 246 } 247 248 static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags) 249 { 250 struct io_ring_ctx *target_ctx = req->file->private_data; 251 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 252 struct io_ring_ctx *ctx = req->ctx; 253 struct file *src_file = msg->src_file; 254 255 if (msg->len) 256 return -EINVAL; 257 if (target_ctx == ctx) 258 return -EINVAL; 259 if (target_ctx->flags & IORING_SETUP_R_DISABLED) 260 return -EBADFD; 261 if (!src_file) { 262 src_file = io_msg_grab_file(req, issue_flags); 263 if (!src_file) 264 return -EBADF; 265 msg->src_file = src_file; 266 req->flags |= REQ_F_NEED_CLEANUP; 267 } 268 269 if (io_msg_need_remote(target_ctx)) 270 return io_msg_fd_remote(req); 271 return io_msg_install_complete(req, issue_flags); 272 } 273 274 int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 275 { 276 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 277 278 if (unlikely(sqe->buf_index || sqe->personality)) 279 return -EINVAL; 280 281 msg->src_file = NULL; 282 msg->user_data = READ_ONCE(sqe->off); 283 msg->len = READ_ONCE(sqe->len); 284 msg->cmd = READ_ONCE(sqe->addr); 285 msg->src_fd = READ_ONCE(sqe->addr3); 286 msg->dst_fd = READ_ONCE(sqe->file_index); 287 msg->flags = READ_ONCE(sqe->msg_ring_flags); 288 if (msg->flags & ~IORING_MSG_RING_MASK) 289 return -EINVAL; 290 291 return 0; 292 } 293 294 int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) 295 { 296 struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); 297 int ret; 298 299 ret = -EBADFD; 300 if (!io_is_uring_fops(req->file)) 301 goto done; 302 303 switch (msg->cmd) { 304 case IORING_MSG_DATA: 305 ret = io_msg_ring_data(req, issue_flags); 306 break; 307 case IORING_MSG_SEND_FD: 308 ret = io_msg_send_fd(req, issue_flags); 309 break; 310 default: 311 ret = -EINVAL; 312 break; 313 } 314 315 done: 316 if (ret < 0) { 317 if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE) 318 return ret; 319 req_set_fail(req); 320 } 321 io_req_set_res(req, ret, 0); 322 return IOU_OK; 323 } 324 325 void io_msg_cache_free(const void *entry) 326 { 327 struct io_kiocb *req = (struct io_kiocb *) entry; 328 329 kmem_cache_free(req_cachep, req); 330 } 331