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_hash(const struct dentry * dentry,struct qstr * qstr)31 static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
32 {
33 	/* Truncate the name in place, avoids having to define a compare
34 	   function. */
35 	if (qstr->len > SYSV_NAMELEN) {
36 		qstr->len = SYSV_NAMELEN;
37 		qstr->hash = full_name_hash(dentry, qstr->name, qstr->len);
38 	}
39 	return 0;
40 }
41 
42 const struct dentry_operations sysv_dentry_operations = {
43 	.d_hash		= sysv_hash,
44 };
45 
sysv_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)46 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
47 {
48 	struct inode * inode = NULL;
49 	ino_t ino;
50 
51 	if (dentry->d_name.len > SYSV_NAMELEN)
52 		return ERR_PTR(-ENAMETOOLONG);
53 	ino = sysv_inode_by_name(dentry);
54 	if (ino)
55 		inode = sysv_iget(dir->i_sb, ino);
56 	return d_splice_alias(inode, dentry);
57 }
58 
sysv_mknod(struct inode * dir,struct dentry * dentry,umode_t mode,dev_t rdev)59 static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
60 {
61 	struct inode * inode;
62 	int err;
63 
64 	if (!old_valid_dev(rdev))
65 		return -EINVAL;
66 
67 	inode = sysv_new_inode(dir, mode);
68 	err = PTR_ERR(inode);
69 
70 	if (!IS_ERR(inode)) {
71 		sysv_set_inode(inode, rdev);
72 		mark_inode_dirty(inode);
73 		err = add_nondir(dentry, inode);
74 	}
75 	return err;
76 }
77 
sysv_create(struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)78 static int sysv_create(struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
79 {
80 	return sysv_mknod(dir, dentry, mode, 0);
81 }
82 
sysv_symlink(struct inode * dir,struct dentry * dentry,const char * symname)83 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
84 	const char * symname)
85 {
86 	int err = -ENAMETOOLONG;
87 	int l = strlen(symname)+1;
88 	struct inode * inode;
89 
90 	if (l > dir->i_sb->s_blocksize)
91 		goto out;
92 
93 	inode = sysv_new_inode(dir, S_IFLNK|0777);
94 	err = PTR_ERR(inode);
95 	if (IS_ERR(inode))
96 		goto out;
97 
98 	sysv_set_inode(inode, 0);
99 	err = page_symlink(inode, symname, l);
100 	if (err)
101 		goto out_fail;
102 
103 	mark_inode_dirty(inode);
104 	err = add_nondir(dentry, inode);
105 out:
106 	return err;
107 
108 out_fail:
109 	inode_dec_link_count(inode);
110 	iput(inode);
111 	goto out;
112 }
113 
sysv_link(struct dentry * old_dentry,struct inode * dir,struct dentry * dentry)114 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
115 	struct dentry * dentry)
116 {
117 	struct inode *inode = d_inode(old_dentry);
118 
119 	inode->i_ctime = current_time(inode);
120 	inode_inc_link_count(inode);
121 	ihold(inode);
122 
123 	return add_nondir(dentry, inode);
124 }
125 
sysv_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)126 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
127 {
128 	struct inode * inode;
129 	int err;
130 
131 	inode_inc_link_count(dir);
132 
133 	inode = sysv_new_inode(dir, S_IFDIR|mode);
134 	err = PTR_ERR(inode);
135 	if (IS_ERR(inode))
136 		goto out_dir;
137 
138 	sysv_set_inode(inode, 0);
139 
140 	inode_inc_link_count(inode);
141 
142 	err = sysv_make_empty(inode, dir);
143 	if (err)
144 		goto out_fail;
145 
146 	err = sysv_add_link(dentry, inode);
147 	if (err)
148 		goto out_fail;
149 
150         d_instantiate(dentry, inode);
151 out:
152 	return err;
153 
154 out_fail:
155 	inode_dec_link_count(inode);
156 	inode_dec_link_count(inode);
157 	iput(inode);
158 out_dir:
159 	inode_dec_link_count(dir);
160 	goto out;
161 }
162 
sysv_unlink(struct inode * dir,struct dentry * dentry)163 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
164 {
165 	struct inode * inode = d_inode(dentry);
166 	struct page * page;
167 	struct sysv_dir_entry * de;
168 	int err = -ENOENT;
169 
170 	de = sysv_find_entry(dentry, &page);
171 	if (!de)
172 		goto out;
173 
174 	err = sysv_delete_entry (de, page);
175 	if (err)
176 		goto out;
177 
178 	inode->i_ctime = dir->i_ctime;
179 	inode_dec_link_count(inode);
180 out:
181 	return err;
182 }
183 
sysv_rmdir(struct inode * dir,struct dentry * dentry)184 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
185 {
186 	struct inode *inode = d_inode(dentry);
187 	int err = -ENOTEMPTY;
188 
189 	if (sysv_empty_dir(inode)) {
190 		err = sysv_unlink(dir, dentry);
191 		if (!err) {
192 			inode->i_size = 0;
193 			inode_dec_link_count(inode);
194 			inode_dec_link_count(dir);
195 		}
196 	}
197 	return err;
198 }
199 
200 /*
201  * Anybody can rename anything with this: the permission checks are left to the
202  * higher-level routines.
203  */
sysv_rename(struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)204 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
205 		       struct inode * new_dir, struct dentry * new_dentry,
206 		       unsigned int flags)
207 {
208 	struct inode * old_inode = d_inode(old_dentry);
209 	struct inode * new_inode = d_inode(new_dentry);
210 	struct page * dir_page = NULL;
211 	struct sysv_dir_entry * dir_de = NULL;
212 	struct page * old_page;
213 	struct sysv_dir_entry * old_de;
214 	int err = -ENOENT;
215 
216 	if (flags & ~RENAME_NOREPLACE)
217 		return -EINVAL;
218 
219 	old_de = sysv_find_entry(old_dentry, &old_page);
220 	if (!old_de)
221 		goto out;
222 
223 	if (S_ISDIR(old_inode->i_mode)) {
224 		err = -EIO;
225 		dir_de = sysv_dotdot(old_inode, &dir_page);
226 		if (!dir_de)
227 			goto out_old;
228 	}
229 
230 	if (new_inode) {
231 		struct page * new_page;
232 		struct sysv_dir_entry * new_de;
233 
234 		err = -ENOTEMPTY;
235 		if (dir_de && !sysv_empty_dir(new_inode))
236 			goto out_dir;
237 
238 		err = -ENOENT;
239 		new_de = sysv_find_entry(new_dentry, &new_page);
240 		if (!new_de)
241 			goto out_dir;
242 		sysv_set_link(new_de, new_page, old_inode);
243 		new_inode->i_ctime = current_time(new_inode);
244 		if (dir_de)
245 			drop_nlink(new_inode);
246 		inode_dec_link_count(new_inode);
247 	} else {
248 		err = sysv_add_link(new_dentry, old_inode);
249 		if (err)
250 			goto out_dir;
251 		if (dir_de)
252 			inode_inc_link_count(new_dir);
253 	}
254 
255 	sysv_delete_entry(old_de, old_page);
256 	mark_inode_dirty(old_inode);
257 
258 	if (dir_de) {
259 		sysv_set_link(dir_de, dir_page, new_dir);
260 		inode_dec_link_count(old_dir);
261 	}
262 	return 0;
263 
264 out_dir:
265 	if (dir_de) {
266 		kunmap(dir_page);
267 		put_page(dir_page);
268 	}
269 out_old:
270 	kunmap(old_page);
271 	put_page(old_page);
272 out:
273 	return err;
274 }
275 
276 /*
277  * directories can handle most operations...
278  */
279 const struct inode_operations sysv_dir_inode_operations = {
280 	.create		= sysv_create,
281 	.lookup		= sysv_lookup,
282 	.link		= sysv_link,
283 	.unlink		= sysv_unlink,
284 	.symlink	= sysv_symlink,
285 	.mkdir		= sysv_mkdir,
286 	.rmdir		= sysv_rmdir,
287 	.mknod		= sysv_mknod,
288 	.rename		= sysv_rename,
289 	.getattr	= sysv_getattr,
290 };
291