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 20 struct 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 35 static void io_double_unlock_ctx(struct io_ring_ctx *octx) 36 { 37 mutex_unlock(&octx->uring_lock); 38 } 39 40 static 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(&octx->uring_lock)) 50 return -EAGAIN; 51 return 0; 52 } 53 mutex_lock(&octx->uring_lock); 54 return 0; 55 } 56 57 void 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 68 static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx) 69 { 70 return target_ctx->task_complete; 71 } 72 73 static 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, req->cqe.user_data, req->cqe.res, req->cqe.flags); 78 kfree_rcu(req, rcu_head); 79 percpu_ref_put(&ctx->refs); 80 } 81 82 static 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(&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, IOU_F_TWQ_LAZY_WAKE); 97 return 0; 98 } 99 100 static 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(target_ctx, target, msg->len, flags, 114 msg->user_data); 115 } 116 117 static 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(target_ctx, msg->user_data, msg->len, flags)) 142 ret = 0; 143 if (target_ctx->flags & IORING_SETUP_IOPOLL) 144 io_double_unlock_ctx(target_ctx); 145 return ret; 146 } 147 148 static 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 } 155 156 static 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(&ctx->file_table.data, msg->src_fd); 165 if (node) { 166 msg->src_file = io_slot_file(node); 167 if (msg->src_file) 168 get_file(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 } 175 176 static 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(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; 203 out_unlock: 204 io_double_unlock_ctx(target_ctx); 205 return ret; 206 } 207 208 static 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 } 220 221 static 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(&msg->tw, io_msg_tw_fd_complete); 231 if (task_work_add(task, &msg->tw, TWA_SIGNAL)) 232 return -EOWNERDEAD; 233 234 return IOU_ISSUE_SKIP_COMPLETE; 235 } 236 237 static 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 } 259 260 static 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 } 277 278 int 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 } 282 283 int 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(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 } 303 304 done: 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, ret, 0); 311 return IOU_COMPLETE; 312 } 313 314 int 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(&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)(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 &io_msg, IO_URING_F_UNLOCKED); 337 } 338