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884c5e68 EB |
1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* | |
3 | * umd - User mode driver support | |
4 | */ | |
5 | #include <linux/shmem_fs.h> | |
6 | #include <linux/pipe_fs_i.h> | |
7 | #include <linux/usermode_driver.h> | |
8 | ||
9 | static LIST_HEAD(umh_list); | |
10 | static DEFINE_MUTEX(umh_list_lock); | |
11 | ||
12 | static int umd_setup(struct subprocess_info *info, struct cred *new) | |
13 | { | |
74be2d3b | 14 | struct umd_info *umd_info = info->data; |
884c5e68 EB |
15 | struct file *from_umh[2]; |
16 | struct file *to_umh[2]; | |
17 | int err; | |
18 | ||
19 | /* create pipe to send data to umh */ | |
20 | err = create_pipe_files(to_umh, 0); | |
21 | if (err) | |
22 | return err; | |
23 | err = replace_fd(0, to_umh[0], 0); | |
24 | fput(to_umh[0]); | |
25 | if (err < 0) { | |
26 | fput(to_umh[1]); | |
27 | return err; | |
28 | } | |
29 | ||
30 | /* create pipe to receive data from umh */ | |
31 | err = create_pipe_files(from_umh, 0); | |
32 | if (err) { | |
33 | fput(to_umh[1]); | |
34 | replace_fd(0, NULL, 0); | |
35 | return err; | |
36 | } | |
37 | err = replace_fd(1, from_umh[1], 0); | |
38 | fput(from_umh[1]); | |
39 | if (err < 0) { | |
40 | fput(to_umh[1]); | |
41 | replace_fd(0, NULL, 0); | |
42 | fput(from_umh[0]); | |
43 | return err; | |
44 | } | |
45 | ||
74be2d3b EB |
46 | umd_info->pipe_to_umh = to_umh[1]; |
47 | umd_info->pipe_from_umh = from_umh[0]; | |
48 | umd_info->pid = task_pid_nr(current); | |
884c5e68 EB |
49 | current->flags |= PF_UMH; |
50 | return 0; | |
51 | } | |
52 | ||
53 | static void umd_cleanup(struct subprocess_info *info) | |
54 | { | |
74be2d3b | 55 | struct umd_info *umd_info = info->data; |
884c5e68 EB |
56 | |
57 | /* cleanup if umh_setup() was successful but exec failed */ | |
58 | if (info->retval) { | |
74be2d3b EB |
59 | fput(umd_info->pipe_to_umh); |
60 | fput(umd_info->pipe_from_umh); | |
884c5e68 EB |
61 | } |
62 | } | |
63 | ||
64 | /** | |
65 | * fork_usermode_blob - fork a blob of bytes as a usermode process | |
66 | * @data: a blob of bytes that can be do_execv-ed as a file | |
67 | * @len: length of the blob | |
68 | * @info: information about usermode process (shouldn't be NULL) | |
69 | * | |
884c5e68 EB |
70 | * Returns either negative error or zero which indicates success |
71 | * in executing a blob of bytes as a usermode process. In such | |
74be2d3b | 72 | * case 'struct umd_info *info' is populated with two pipes |
884c5e68 EB |
73 | * and a pid of the process. The caller is responsible for health |
74 | * check of the user process, killing it via pid, and closing the | |
75 | * pipes when user process is no longer needed. | |
76 | */ | |
74be2d3b | 77 | int fork_usermode_blob(void *data, size_t len, struct umd_info *info) |
884c5e68 | 78 | { |
884c5e68 EB |
79 | struct subprocess_info *sub_info; |
80 | char **argv = NULL; | |
81 | struct file *file; | |
82 | ssize_t written; | |
83 | loff_t pos = 0; | |
84 | int err; | |
85 | ||
1199c6c3 | 86 | file = shmem_kernel_file_setup(info->driver_name, len, 0); |
884c5e68 EB |
87 | if (IS_ERR(file)) |
88 | return PTR_ERR(file); | |
89 | ||
90 | written = kernel_write(file, data, len, &pos); | |
91 | if (written != len) { | |
92 | err = written; | |
93 | if (err >= 0) | |
94 | err = -ENOMEM; | |
95 | goto out; | |
96 | } | |
97 | ||
98 | err = -ENOMEM; | |
1199c6c3 | 99 | argv = argv_split(GFP_KERNEL, info->driver_name, NULL); |
884c5e68 EB |
100 | if (!argv) |
101 | goto out; | |
102 | ||
1199c6c3 EB |
103 | sub_info = call_usermodehelper_setup(info->driver_name, argv, NULL, |
104 | GFP_KERNEL, | |
884c5e68 EB |
105 | umd_setup, umd_cleanup, info); |
106 | if (!sub_info) | |
107 | goto out; | |
108 | ||
109 | sub_info->file = file; | |
110 | err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); | |
111 | if (!err) { | |
112 | mutex_lock(&umh_list_lock); | |
113 | list_add(&info->list, &umh_list); | |
114 | mutex_unlock(&umh_list_lock); | |
115 | } | |
116 | out: | |
117 | if (argv) | |
118 | argv_free(argv); | |
119 | fput(file); | |
120 | return err; | |
121 | } | |
122 | EXPORT_SYMBOL_GPL(fork_usermode_blob); | |
123 | ||
124 | void __exit_umh(struct task_struct *tsk) | |
125 | { | |
74be2d3b | 126 | struct umd_info *info; |
884c5e68 EB |
127 | pid_t pid = tsk->pid; |
128 | ||
129 | mutex_lock(&umh_list_lock); | |
130 | list_for_each_entry(info, &umh_list, list) { | |
131 | if (info->pid == pid) { | |
132 | list_del(&info->list); | |
133 | mutex_unlock(&umh_list_lock); | |
134 | goto out; | |
135 | } | |
136 | } | |
137 | mutex_unlock(&umh_list_lock); | |
138 | return; | |
139 | out: | |
140 | if (info->cleanup) | |
141 | info->cleanup(info); | |
142 | } | |
143 |