1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Routines that mimic syscalls, but don't use the user address space or file
4 * descriptors. Only for init/ and related early init code.
5 */
6 #include <linux/init.h>
7 #include <linux/mount.h>
8 #include <linux/namei.h>
9 #include <linux/fs.h>
10 #include <linux/fs_struct.h>
11 #include <linux/file.h>
12 #include <linux/init_syscalls.h>
13 #include <linux/security.h>
14 #include "internal.h"
15
16 int __init init_mount(const char *dev_name, const char *dir_name,
17 const char *type_page, unsigned long flags, void *data_page)
18 {
19 struct path path;
20 int ret;
21
22 ret = kern_path(dir_name, LOOKUP_FOLLOW, &path);
23 if (ret)
24 return ret;
25 ret = path_mount(dev_name, &path, type_page, flags, data_page);
26 path_put(&path);
27 return ret;
28 }
29
30 int __init init_umount(const char *name, int flags)
31 {
32 int lookup_flags = LOOKUP_MOUNTPOINT;
33 struct path path;
34 int ret;
35
36 if (!(flags & UMOUNT_NOFOLLOW))
37 lookup_flags |= LOOKUP_FOLLOW;
38 ret = kern_path(name, lookup_flags, &path);
39 if (ret)
40 return ret;
41 return path_umount(&path, flags);
42 }
43
44 int __init init_chdir(const char *filename)
45 {
46 struct path path;
47 int error;
48
49 error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
50 if (error)
51 return error;
52 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
53 if (!error)
54 set_fs_pwd(current->fs, &path);
55 path_put(&path);
56 return error;
57 }
58
59 int __init init_chroot(const char *filename)
60 {
61 struct path path;
62 int error;
63
64 error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
65 if (error)
66 return error;
67 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
68 if (error)
69 goto dput_and_out;
70 error = -EPERM;
71 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
72 goto dput_and_out;
73 error = security_path_chroot(&path);
74 if (error)
75 goto dput_and_out;
76 set_fs_root(current->fs, &path);
77 dput_and_out:
78 path_put(&path);
79 return error;
80 }
81
82 int __init init_chown(const char *filename, uid_t user, gid_t group, int flags)
83 {
84 int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
85 struct path path;
86 int error;
87
88 error = kern_path(filename, lookup_flags, &path);
89 if (error)
90 return error;
91 error = mnt_want_write(path.mnt);
92 if (!error) {
93 error = chown_common(&path, user, group);
94 mnt_drop_write(path.mnt);
95 }
96 path_put(&path);
97 return error;
98 }
99
100 int __init init_chmod(const char *filename, umode_t mode)
101 {
102 struct path path;
103 int error;
104
105 error = kern_path(filename, LOOKUP_FOLLOW, &path);
106 if (error)
107 return error;
108 error = chmod_common(&path, mode);
109 path_put(&path);
110 return error;
111 }
112
113 int __init init_eaccess(const char *filename)
114 {
115 struct path path;
116 int error;
117
118 error = kern_path(filename, LOOKUP_FOLLOW, &path);
119 if (error)
120 return error;
121 error = path_permission(&path, MAY_ACCESS);
122 path_put(&path);
123 return error;
124 }
125
126 int __init init_stat(const char *filename, struct kstat *stat, int flags)
127 {
128 int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
129 struct path path;
130 int error;
131
132 error = kern_path(filename, lookup_flags, &path);
133 if (error)
134 return error;
135 error = vfs_getattr(&path, stat, STATX_BASIC_STATS,
136 flags | AT_NO_AUTOMOUNT);
137 path_put(&path);
138 return error;
139 }
140
141 int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
142 {
143 struct dentry *dentry;
144 struct path path;
145 int error;
146
147 if (S_ISFIFO(mode) || S_ISSOCK(mode))
148 dev = 0;
149 else if (!(S_ISBLK(mode) || S_ISCHR(mode)))
150 return -EINVAL;
151
152 dentry = kern_path_create(AT_FDCWD, filename, &path, 0);
153 if (IS_ERR(dentry))
154 return PTR_ERR(dentry);
155
156 mode = mode_strip_umask(d_inode(path.dentry), mode);
157 error = security_path_mknod(&path, dentry, mode, dev);
158 if (!error)
159 error = vfs_mknod(mnt_idmap(path.mnt), path.dentry->d_inode,
160 dentry, mode, new_decode_dev(dev));
161 done_path_create(&path, dentry);
162 return error;
163 }
164
165 int __init init_link(const char *oldname, const char *newname)
166 {
167 struct dentry *new_dentry;
168 struct path old_path, new_path;
169 struct mnt_idmap *idmap;
170 int error;
171
172 error = kern_path(oldname, 0, &old_path);
173 if (error)
174 return error;
175
176 new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0);
177 error = PTR_ERR(new_dentry);
178 if (IS_ERR(new_dentry))
179 goto out;
180
181 error = -EXDEV;
182 if (old_path.mnt != new_path.mnt)
183 goto out_dput;
184 idmap = mnt_idmap(new_path.mnt);
185 error = may_linkat(idmap, &old_path);
186 if (unlikely(error))
187 goto out_dput;
188 error = security_path_link(old_path.dentry, &new_path, new_dentry);
189 if (error)
190 goto out_dput;
191 error = vfs_link(old_path.dentry, idmap, new_path.dentry->d_inode,
192 new_dentry, NULL);
193 out_dput:
194 done_path_create(&new_path, new_dentry);
195 out:
196 path_put(&old_path);
197 return error;
198 }
199
200 int __init init_symlink(const char *oldname, const char *newname)
201 {
202 struct dentry *dentry;
203 struct path path;
204 int error;
205
206 dentry = kern_path_create(AT_FDCWD, newname, &path, 0);
207 if (IS_ERR(dentry))
208 return PTR_ERR(dentry);
209 error = security_path_symlink(&path, dentry, oldname);
210 if (!error)
211 error = vfs_symlink(mnt_idmap(path.mnt), path.dentry->d_inode,
212 dentry, oldname);
213 done_path_create(&path, dentry);
214 return error;
215 }
216
217 int __init init_unlink(const char *pathname)
218 {
219 return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
220 }
221
222 int __init init_mkdir(const char *pathname, umode_t mode)
223 {
224 struct dentry *dentry;
225 struct path path;
226 int error;
227
228 dentry = kern_path_create(AT_FDCWD, pathname, &path, LOOKUP_DIRECTORY);
229 if (IS_ERR(dentry))
230 return PTR_ERR(dentry);
231 mode = mode_strip_umask(d_inode(path.dentry), mode);
232 error = security_path_mkdir(&path, dentry, mode);
233 if (!error)
234 error = vfs_mkdir(mnt_idmap(path.mnt), path.dentry->d_inode,
235 dentry, mode);
236 done_path_create(&path, dentry);
237 return error;
238 }
239
240 int __init init_rmdir(const char *pathname)
241 {
242 return do_rmdir(AT_FDCWD, getname_kernel(pathname));
243 }
244
245 int __init init_utimes(char *filename, struct timespec64 *ts)
246 {
247 struct path path;
248 int error;
249
250 error = kern_path(filename, 0, &path);
251 if (error)
252 return error;
253 error = vfs_utimes(&path, ts);
254 path_put(&path);
255 return error;
256 }
257
258 int __init init_dup(struct file *file)
259 {
260 int fd;
261
262 fd = get_unused_fd_flags(0);
263 if (fd < 0)
264 return fd;
265 fd_install(fd, get_file(file));
266 return 0;
267 }
268
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