1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/sysv/namei.c
4 *
5 * minix/namei.c
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * coh/namei.c
9 * Copyright (C) 1993 Pascal Haible, Bruno Haible
10 *
11 * sysv/namei.c
12 * Copyright (C) 1993 Bruno Haible
13 * Copyright (C) 1997, 1998 Krzysztof G. Baranowski
14 */
15
16 #include <linux/pagemap.h>
17 #include "sysv.h"
18
add_nondir(struct dentry * dentry,struct inode * inode)19 static int add_nondir(struct dentry *dentry, struct inode *inode)
20 {
21 int err = sysv_add_link(dentry, inode);
22 if (!err) {
23 d_instantiate(dentry, inode);
24 return 0;
25 }
26 inode_dec_link_count(inode);
27 iput(inode);
28 return err;
29 }
30
sysv_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)31 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
32 {
33 struct inode * inode = NULL;
34 ino_t ino;
35
36 if (dentry->d_name.len > SYSV_NAMELEN)
37 return ERR_PTR(-ENAMETOOLONG);
38 ino = sysv_inode_by_name(dentry);
39 if (ino)
40 inode = sysv_iget(dir->i_sb, ino);
41 return d_splice_alias(inode, dentry);
42 }
43
sysv_mknod(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)44 static int sysv_mknod(struct user_namespace *mnt_userns, struct inode *dir,
45 struct dentry *dentry, umode_t mode, dev_t rdev)
46 {
47 struct inode * inode;
48 int err;
49
50 if (!old_valid_dev(rdev))
51 return -EINVAL;
52
53 inode = sysv_new_inode(dir, mode);
54 err = PTR_ERR(inode);
55
56 if (!IS_ERR(inode)) {
57 sysv_set_inode(inode, rdev);
58 mark_inode_dirty(inode);
59 err = add_nondir(dentry, inode);
60 }
61 return err;
62 }
63
sysv_create(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)64 static int sysv_create(struct user_namespace *mnt_userns, struct inode *dir,
65 struct dentry *dentry, umode_t mode, bool excl)
66 {
67 return sysv_mknod(&init_user_ns, dir, dentry, mode, 0);
68 }
69
sysv_symlink(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,const char * symname)70 static int sysv_symlink(struct user_namespace *mnt_userns, struct inode *dir,
71 struct dentry *dentry, const char *symname)
72 {
73 int err = -ENAMETOOLONG;
74 int l = strlen(symname)+1;
75 struct inode * inode;
76
77 if (l > dir->i_sb->s_blocksize)
78 goto out;
79
80 inode = sysv_new_inode(dir, S_IFLNK|0777);
81 err = PTR_ERR(inode);
82 if (IS_ERR(inode))
83 goto out;
84
85 sysv_set_inode(inode, 0);
86 err = page_symlink(inode, symname, l);
87 if (err)
88 goto out_fail;
89
90 mark_inode_dirty(inode);
91 err = add_nondir(dentry, inode);
92 out:
93 return err;
94
95 out_fail:
96 inode_dec_link_count(inode);
97 iput(inode);
98 goto out;
99 }
100
sysv_link(struct dentry * old_dentry,struct inode * dir,struct dentry * dentry)101 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
102 struct dentry * dentry)
103 {
104 struct inode *inode = d_inode(old_dentry);
105
106 inode->i_ctime = current_time(inode);
107 inode_inc_link_count(inode);
108 ihold(inode);
109
110 return add_nondir(dentry, inode);
111 }
112
sysv_mkdir(struct user_namespace * mnt_userns,struct inode * dir,struct dentry * dentry,umode_t mode)113 static int sysv_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
114 struct dentry *dentry, umode_t mode)
115 {
116 struct inode * inode;
117 int err;
118
119 inode_inc_link_count(dir);
120
121 inode = sysv_new_inode(dir, S_IFDIR|mode);
122 err = PTR_ERR(inode);
123 if (IS_ERR(inode))
124 goto out_dir;
125
126 sysv_set_inode(inode, 0);
127
128 inode_inc_link_count(inode);
129
130 err = sysv_make_empty(inode, dir);
131 if (err)
132 goto out_fail;
133
134 err = sysv_add_link(dentry, inode);
135 if (err)
136 goto out_fail;
137
138 d_instantiate(dentry, inode);
139 out:
140 return err;
141
142 out_fail:
143 inode_dec_link_count(inode);
144 inode_dec_link_count(inode);
145 iput(inode);
146 out_dir:
147 inode_dec_link_count(dir);
148 goto out;
149 }
150
sysv_unlink(struct inode * dir,struct dentry * dentry)151 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
152 {
153 struct inode * inode = d_inode(dentry);
154 struct page * page;
155 struct sysv_dir_entry * de;
156 int err = -ENOENT;
157
158 de = sysv_find_entry(dentry, &page);
159 if (!de)
160 goto out;
161
162 err = sysv_delete_entry (de, page);
163 if (err)
164 goto out;
165
166 inode->i_ctime = dir->i_ctime;
167 inode_dec_link_count(inode);
168 out:
169 return err;
170 }
171
sysv_rmdir(struct inode * dir,struct dentry * dentry)172 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
173 {
174 struct inode *inode = d_inode(dentry);
175 int err = -ENOTEMPTY;
176
177 if (sysv_empty_dir(inode)) {
178 err = sysv_unlink(dir, dentry);
179 if (!err) {
180 inode->i_size = 0;
181 inode_dec_link_count(inode);
182 inode_dec_link_count(dir);
183 }
184 }
185 return err;
186 }
187
188 /*
189 * Anybody can rename anything with this: the permission checks are left to the
190 * higher-level routines.
191 */
sysv_rename(struct user_namespace * mnt_userns,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)192 static int sysv_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
193 struct dentry *old_dentry, struct inode *new_dir,
194 struct dentry *new_dentry, unsigned int flags)
195 {
196 struct inode * old_inode = d_inode(old_dentry);
197 struct inode * new_inode = d_inode(new_dentry);
198 struct page * dir_page = NULL;
199 struct sysv_dir_entry * dir_de = NULL;
200 struct page * old_page;
201 struct sysv_dir_entry * old_de;
202 int err = -ENOENT;
203
204 if (flags & ~RENAME_NOREPLACE)
205 return -EINVAL;
206
207 old_de = sysv_find_entry(old_dentry, &old_page);
208 if (!old_de)
209 goto out;
210
211 if (S_ISDIR(old_inode->i_mode)) {
212 err = -EIO;
213 dir_de = sysv_dotdot(old_inode, &dir_page);
214 if (!dir_de)
215 goto out_old;
216 }
217
218 if (new_inode) {
219 struct page * new_page;
220 struct sysv_dir_entry * new_de;
221
222 err = -ENOTEMPTY;
223 if (dir_de && !sysv_empty_dir(new_inode))
224 goto out_dir;
225
226 err = -ENOENT;
227 new_de = sysv_find_entry(new_dentry, &new_page);
228 if (!new_de)
229 goto out_dir;
230 sysv_set_link(new_de, new_page, old_inode);
231 new_inode->i_ctime = current_time(new_inode);
232 if (dir_de)
233 drop_nlink(new_inode);
234 inode_dec_link_count(new_inode);
235 } else {
236 err = sysv_add_link(new_dentry, old_inode);
237 if (err)
238 goto out_dir;
239 if (dir_de)
240 inode_inc_link_count(new_dir);
241 }
242
243 sysv_delete_entry(old_de, old_page);
244 mark_inode_dirty(old_inode);
245
246 if (dir_de) {
247 sysv_set_link(dir_de, dir_page, new_dir);
248 inode_dec_link_count(old_dir);
249 }
250 return 0;
251
252 out_dir:
253 if (dir_de) {
254 kunmap(dir_page);
255 put_page(dir_page);
256 }
257 out_old:
258 kunmap(old_page);
259 put_page(old_page);
260 out:
261 return err;
262 }
263
264 /*
265 * directories can handle most operations...
266 */
267 const struct inode_operations sysv_dir_inode_operations = {
268 .create = sysv_create,
269 .lookup = sysv_lookup,
270 .link = sysv_link,
271 .unlink = sysv_unlink,
272 .symlink = sysv_symlink,
273 .mkdir = sysv_mkdir,
274 .rmdir = sysv_rmdir,
275 .mknod = sysv_mknod,
276 .rename = sysv_rename,
277 .getattr = sysv_getattr,
278 };
279