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12#include <linux/cred.h>
13#include <linux/file.h>
14#include <linux/poll.h>
15#include <linux/sched.h>
16#include <linux/init.h>
17#include <linux/fs.h>
18#include <linux/mount.h>
19#include <linux/module.h>
20#include <linux/kernel.h>
21#include <linux/magic.h>
22#include <linux/anon_inodes.h>
23#include <linux/pseudo_fs.h>
24
25#include <linux/uaccess.h>
26
27static struct vfsmount *anon_inode_mnt __read_mostly;
28static struct inode *anon_inode_inode;
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33static char *anon_inodefs_dname(struct dentry *dentry, char *buffer, int buflen)
34{
35 return dynamic_dname(dentry, buffer, buflen, "anon_inode:%s",
36 dentry->d_name.name);
37}
38
39static const struct dentry_operations anon_inodefs_dentry_operations = {
40 .d_dname = anon_inodefs_dname,
41};
42
43static int anon_inodefs_init_fs_context(struct fs_context *fc)
44{
45 struct pseudo_fs_context *ctx = init_pseudo(fc, ANON_INODE_FS_MAGIC);
46 if (!ctx)
47 return -ENOMEM;
48 ctx->dops = &anon_inodefs_dentry_operations;
49 return 0;
50}
51
52static struct file_system_type anon_inode_fs_type = {
53 .name = "anon_inodefs",
54 .init_fs_context = anon_inodefs_init_fs_context,
55 .kill_sb = kill_anon_super,
56};
57
58static struct inode *anon_inode_make_secure_inode(
59 const char *name,
60 const struct inode *context_inode)
61{
62 struct inode *inode;
63 const struct qstr qname = QSTR_INIT(name, strlen(name));
64 int error;
65
66 inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
67 if (IS_ERR(inode))
68 return inode;
69 inode->i_flags &= ~S_PRIVATE;
70 error = security_inode_init_security_anon(inode, &qname, context_inode);
71 if (error) {
72 iput(inode);
73 return ERR_PTR(error);
74 }
75 return inode;
76}
77
78static struct file *__anon_inode_getfile(const char *name,
79 const struct file_operations *fops,
80 void *priv, int flags,
81 const struct inode *context_inode,
82 bool secure)
83{
84 struct inode *inode;
85 struct file *file;
86
87 if (fops->owner && !try_module_get(fops->owner))
88 return ERR_PTR(-ENOENT);
89
90 if (secure) {
91 inode = anon_inode_make_secure_inode(name, context_inode);
92 if (IS_ERR(inode)) {
93 file = ERR_CAST(inode);
94 goto err;
95 }
96 } else {
97 inode = anon_inode_inode;
98 if (IS_ERR(inode)) {
99 file = ERR_PTR(-ENODEV);
100 goto err;
101 }
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105
106 ihold(inode);
107 }
108
109 file = alloc_file_pseudo(inode, anon_inode_mnt, name,
110 flags & (O_ACCMODE | O_NONBLOCK), fops);
111 if (IS_ERR(file))
112 goto err_iput;
113
114 file->f_mapping = inode->i_mapping;
115
116 file->private_data = priv;
117
118 return file;
119
120err_iput:
121 iput(inode);
122err:
123 module_put(fops->owner);
124 return file;
125}
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143struct file *anon_inode_getfile(const char *name,
144 const struct file_operations *fops,
145 void *priv, int flags)
146{
147 return __anon_inode_getfile(name, fops, priv, flags, NULL, false);
148}
149EXPORT_SYMBOL_GPL(anon_inode_getfile);
150
151static int __anon_inode_getfd(const char *name,
152 const struct file_operations *fops,
153 void *priv, int flags,
154 const struct inode *context_inode,
155 bool secure)
156{
157 int error, fd;
158 struct file *file;
159
160 error = get_unused_fd_flags(flags);
161 if (error < 0)
162 return error;
163 fd = error;
164
165 file = __anon_inode_getfile(name, fops, priv, flags, context_inode,
166 secure);
167 if (IS_ERR(file)) {
168 error = PTR_ERR(file);
169 goto err_put_unused_fd;
170 }
171 fd_install(fd, file);
172
173 return fd;
174
175err_put_unused_fd:
176 put_unused_fd(fd);
177 return error;
178}
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197int anon_inode_getfd(const char *name, const struct file_operations *fops,
198 void *priv, int flags)
199{
200 return __anon_inode_getfd(name, fops, priv, flags, NULL, false);
201}
202EXPORT_SYMBOL_GPL(anon_inode_getfd);
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220int anon_inode_getfd_secure(const char *name, const struct file_operations *fops,
221 void *priv, int flags,
222 const struct inode *context_inode)
223{
224 return __anon_inode_getfd(name, fops, priv, flags, context_inode, true);
225}
226EXPORT_SYMBOL_GPL(anon_inode_getfd_secure);
227
228static int __init anon_inode_init(void)
229{
230 anon_inode_mnt = kern_mount(&anon_inode_fs_type);
231 if (IS_ERR(anon_inode_mnt))
232 panic("anon_inode_init() kernel mount failed (%ld)\n", PTR_ERR(anon_inode_mnt));
233
234 anon_inode_inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
235 if (IS_ERR(anon_inode_inode))
236 panic("anon_inode_init() inode allocation failed (%ld)\n", PTR_ERR(anon_inode_inode));
237
238 return 0;
239}
240
241fs_initcall(anon_inode_init);
242
243