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