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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; | |
18 | u64 user_data; | |
19 | u32 len; | |
e6130eba JA |
20 | u32 cmd; |
21 | u32 src_fd; | |
22 | u32 dst_fd; | |
23 | u32 flags; | |
36404b09 JA |
24 | }; |
25 | ||
e6130eba JA |
26 | static int io_msg_ring_data(struct io_kiocb *req) |
27 | { | |
28 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
29 | struct io_msg *msg = io_kiocb_to_cmd(req); | |
30 | ||
31 | if (msg->src_fd || msg->dst_fd || msg->flags) | |
32 | return -EINVAL; | |
33 | ||
52120f0f | 34 | if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0, true)) |
e6130eba JA |
35 | return 0; |
36 | ||
37 | return -EOVERFLOW; | |
38 | } | |
39 | ||
40 | static void io_double_unlock_ctx(struct io_ring_ctx *ctx, | |
41 | struct io_ring_ctx *octx, | |
42 | unsigned int issue_flags) | |
43 | { | |
44 | if (issue_flags & IO_URING_F_UNLOCKED) | |
45 | mutex_unlock(&ctx->uring_lock); | |
46 | mutex_unlock(&octx->uring_lock); | |
47 | } | |
48 | ||
49 | static int io_double_lock_ctx(struct io_ring_ctx *ctx, | |
50 | struct io_ring_ctx *octx, | |
51 | unsigned int issue_flags) | |
52 | { | |
53 | /* | |
54 | * To ensure proper ordering between the two ctxs, we can only | |
55 | * attempt a trylock on the target. If that fails and we already have | |
56 | * the source ctx lock, punt to io-wq. | |
57 | */ | |
58 | if (!(issue_flags & IO_URING_F_UNLOCKED)) { | |
59 | if (!mutex_trylock(&octx->uring_lock)) | |
60 | return -EAGAIN; | |
61 | return 0; | |
62 | } | |
63 | ||
64 | /* Always grab smallest value ctx first. We know ctx != octx. */ | |
65 | if (ctx < octx) { | |
66 | mutex_lock(&ctx->uring_lock); | |
67 | mutex_lock(&octx->uring_lock); | |
68 | } else { | |
69 | mutex_lock(&octx->uring_lock); | |
70 | mutex_lock(&ctx->uring_lock); | |
71 | } | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags) | |
77 | { | |
78 | struct io_ring_ctx *target_ctx = req->file->private_data; | |
79 | struct io_msg *msg = io_kiocb_to_cmd(req); | |
80 | struct io_ring_ctx *ctx = req->ctx; | |
81 | unsigned long file_ptr; | |
82 | struct file *src_file; | |
83 | int ret; | |
84 | ||
85 | if (target_ctx == ctx) | |
86 | return -EINVAL; | |
87 | ||
88 | ret = io_double_lock_ctx(ctx, target_ctx, issue_flags); | |
89 | if (unlikely(ret)) | |
90 | return ret; | |
91 | ||
92 | ret = -EBADF; | |
93 | if (unlikely(msg->src_fd >= ctx->nr_user_files)) | |
94 | goto out_unlock; | |
95 | ||
96 | msg->src_fd = array_index_nospec(msg->src_fd, ctx->nr_user_files); | |
97 | file_ptr = io_fixed_file_slot(&ctx->file_table, msg->src_fd)->file_ptr; | |
98 | src_file = (struct file *) (file_ptr & FFS_MASK); | |
99 | get_file(src_file); | |
100 | ||
101 | ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd); | |
102 | if (ret < 0) { | |
103 | fput(src_file); | |
104 | goto out_unlock; | |
105 | } | |
106 | ||
107 | if (msg->flags & IORING_MSG_RING_CQE_SKIP) | |
108 | goto out_unlock; | |
109 | ||
110 | /* | |
111 | * If this fails, the target still received the file descriptor but | |
112 | * wasn't notified of the fact. This means that if this request | |
113 | * completes with -EOVERFLOW, then the sender must ensure that a | |
114 | * later IORING_OP_MSG_RING delivers the message. | |
115 | */ | |
52120f0f | 116 | if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0, true)) |
e6130eba JA |
117 | ret = -EOVERFLOW; |
118 | out_unlock: | |
119 | io_double_unlock_ctx(ctx, target_ctx, issue_flags); | |
120 | return ret; | |
121 | } | |
122 | ||
36404b09 JA |
123 | int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) |
124 | { | |
125 | struct io_msg *msg = io_kiocb_to_cmd(req); | |
126 | ||
e6130eba | 127 | if (unlikely(sqe->buf_index || sqe->personality)) |
36404b09 JA |
128 | return -EINVAL; |
129 | ||
130 | msg->user_data = READ_ONCE(sqe->off); | |
131 | msg->len = READ_ONCE(sqe->len); | |
e6130eba JA |
132 | msg->cmd = READ_ONCE(sqe->addr); |
133 | msg->src_fd = READ_ONCE(sqe->addr3); | |
134 | msg->dst_fd = READ_ONCE(sqe->file_index); | |
135 | msg->flags = READ_ONCE(sqe->msg_ring_flags); | |
136 | if (msg->flags & ~IORING_MSG_RING_CQE_SKIP) | |
137 | return -EINVAL; | |
138 | ||
36404b09 JA |
139 | return 0; |
140 | } | |
141 | ||
142 | int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) | |
143 | { | |
144 | struct io_msg *msg = io_kiocb_to_cmd(req); | |
36404b09 JA |
145 | int ret; |
146 | ||
147 | ret = -EBADFD; | |
148 | if (!io_is_uring_fops(req->file)) | |
149 | goto done; | |
150 | ||
e6130eba JA |
151 | switch (msg->cmd) { |
152 | case IORING_MSG_DATA: | |
153 | ret = io_msg_ring_data(req); | |
154 | break; | |
155 | case IORING_MSG_SEND_FD: | |
156 | ret = io_msg_send_fd(req, issue_flags); | |
157 | break; | |
158 | default: | |
159 | ret = -EINVAL; | |
160 | break; | |
161 | } | |
36404b09 JA |
162 | |
163 | done: | |
164 | if (ret < 0) | |
165 | req_set_fail(req); | |
166 | io_req_set_res(req, ret, 0); | |
167 | /* put file to avoid an attempt to IOPOLL the req */ | |
168 | io_put_file(req->file); | |
169 | req->file = NULL; | |
170 | return IOU_OK; | |
171 | } |