xref: /openbmc/linux/fs/openpromfs/inode.c (revision ae213c44) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* inode.c: /proc/openprom handling routines
3  *
4  * Copyright (C) 1996-1999 Jakub Jelinek  (jakub@redhat.com)
5  * Copyright (C) 1998      Eddie C. Dost  (ecd@skynet.be)
6  */
7 
8 #include <linux/module.h>
9 #include <linux/types.h>
10 #include <linux/string.h>
11 #include <linux/fs.h>
12 #include <linux/init.h>
13 #include <linux/slab.h>
14 #include <linux/seq_file.h>
15 #include <linux/magic.h>
16 
17 #include <asm/openprom.h>
18 #include <asm/oplib.h>
19 #include <asm/prom.h>
20 #include <linux/uaccess.h>
21 
22 static DEFINE_MUTEX(op_mutex);
23 
24 #define OPENPROM_ROOT_INO	0
25 
26 enum op_inode_type {
27 	op_inode_node,
28 	op_inode_prop,
29 };
30 
31 union op_inode_data {
32 	struct device_node	*node;
33 	struct property		*prop;
34 };
35 
36 struct op_inode_info {
37 	struct inode		vfs_inode;
38 	enum op_inode_type	type;
39 	union op_inode_data	u;
40 };
41 
42 static struct inode *openprom_iget(struct super_block *sb, ino_t ino);
43 
44 static inline struct op_inode_info *OP_I(struct inode *inode)
45 {
46 	return container_of(inode, struct op_inode_info, vfs_inode);
47 }
48 
49 static int is_string(unsigned char *p, int len)
50 {
51 	int i;
52 
53 	for (i = 0; i < len; i++) {
54 		unsigned char val = p[i];
55 
56 		if ((i && !val) ||
57 		    (val >= ' ' && val <= '~'))
58 			continue;
59 
60 		return 0;
61 	}
62 
63 	return 1;
64 }
65 
66 static int property_show(struct seq_file *f, void *v)
67 {
68 	struct property *prop = f->private;
69 	void *pval;
70 	int len;
71 
72 	len = prop->length;
73 	pval = prop->value;
74 
75 	if (is_string(pval, len)) {
76 		while (len > 0) {
77 			int n = strlen(pval);
78 
79 			seq_printf(f, "%s", (char *) pval);
80 
81 			/* Skip over the NULL byte too.  */
82 			pval += n + 1;
83 			len -= n + 1;
84 
85 			if (len > 0)
86 				seq_printf(f, " + ");
87 		}
88 	} else {
89 		if (len & 3) {
90 			while (len) {
91 				len--;
92 				if (len)
93 					seq_printf(f, "%02x.",
94 						   *(unsigned char *) pval);
95 				else
96 					seq_printf(f, "%02x",
97 						   *(unsigned char *) pval);
98 				pval++;
99 			}
100 		} else {
101 			while (len >= 4) {
102 				len -= 4;
103 
104 				if (len)
105 					seq_printf(f, "%08x.",
106 						   *(unsigned int *) pval);
107 				else
108 					seq_printf(f, "%08x",
109 						   *(unsigned int *) pval);
110 				pval += 4;
111 			}
112 		}
113 	}
114 	seq_printf(f, "\n");
115 
116 	return 0;
117 }
118 
119 static void *property_start(struct seq_file *f, loff_t *pos)
120 {
121 	if (*pos == 0)
122 		return pos;
123 	return NULL;
124 }
125 
126 static void *property_next(struct seq_file *f, void *v, loff_t *pos)
127 {
128 	(*pos)++;
129 	return NULL;
130 }
131 
132 static void property_stop(struct seq_file *f, void *v)
133 {
134 	/* Nothing to do */
135 }
136 
137 static const struct seq_operations property_op = {
138 	.start		= property_start,
139 	.next		= property_next,
140 	.stop		= property_stop,
141 	.show		= property_show
142 };
143 
144 static int property_open(struct inode *inode, struct file *file)
145 {
146 	struct op_inode_info *oi = OP_I(inode);
147 	int ret;
148 
149 	BUG_ON(oi->type != op_inode_prop);
150 
151 	ret = seq_open(file, &property_op);
152 	if (!ret) {
153 		struct seq_file *m = file->private_data;
154 		m->private = oi->u.prop;
155 	}
156 	return ret;
157 }
158 
159 static const struct file_operations openpromfs_prop_ops = {
160 	.open		= property_open,
161 	.read		= seq_read,
162 	.llseek		= seq_lseek,
163 	.release	= seq_release,
164 };
165 
166 static int openpromfs_readdir(struct file *, struct dir_context *);
167 
168 static const struct file_operations openprom_operations = {
169 	.read		= generic_read_dir,
170 	.iterate_shared	= openpromfs_readdir,
171 	.llseek		= generic_file_llseek,
172 };
173 
174 static struct dentry *openpromfs_lookup(struct inode *, struct dentry *, unsigned int);
175 
176 static const struct inode_operations openprom_inode_operations = {
177 	.lookup		= openpromfs_lookup,
178 };
179 
180 static struct dentry *openpromfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
181 {
182 	struct op_inode_info *ent_oi, *oi = OP_I(dir);
183 	struct device_node *dp, *child;
184 	struct property *prop;
185 	enum op_inode_type ent_type;
186 	union op_inode_data ent_data;
187 	const char *name;
188 	struct inode *inode;
189 	unsigned int ino;
190 	int len;
191 
192 	BUG_ON(oi->type != op_inode_node);
193 
194 	dp = oi->u.node;
195 
196 	name = dentry->d_name.name;
197 	len = dentry->d_name.len;
198 
199 	mutex_lock(&op_mutex);
200 
201 	child = dp->child;
202 	while (child) {
203 		const char *node_name = kbasename(child->full_name);
204 		int n = strlen(node_name);
205 
206 		if (len == n &&
207 		    !strncmp(node_name, name, len)) {
208 			ent_type = op_inode_node;
209 			ent_data.node = child;
210 			ino = child->unique_id;
211 			goto found;
212 		}
213 		child = child->sibling;
214 	}
215 
216 	prop = dp->properties;
217 	while (prop) {
218 		int n = strlen(prop->name);
219 
220 		if (len == n && !strncmp(prop->name, name, len)) {
221 			ent_type = op_inode_prop;
222 			ent_data.prop = prop;
223 			ino = prop->unique_id;
224 			goto found;
225 		}
226 
227 		prop = prop->next;
228 	}
229 
230 	mutex_unlock(&op_mutex);
231 	return ERR_PTR(-ENOENT);
232 
233 found:
234 	inode = openprom_iget(dir->i_sb, ino);
235 	mutex_unlock(&op_mutex);
236 	if (IS_ERR(inode))
237 		return ERR_CAST(inode);
238 	ent_oi = OP_I(inode);
239 	ent_oi->type = ent_type;
240 	ent_oi->u = ent_data;
241 
242 	switch (ent_type) {
243 	case op_inode_node:
244 		inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
245 		inode->i_op = &openprom_inode_operations;
246 		inode->i_fop = &openprom_operations;
247 		set_nlink(inode, 2);
248 		break;
249 	case op_inode_prop:
250 		if (of_node_name_eq(dp, "options") && (len == 17) &&
251 		    !strncmp (name, "security-password", 17))
252 			inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
253 		else
254 			inode->i_mode = S_IFREG | S_IRUGO;
255 		inode->i_fop = &openpromfs_prop_ops;
256 		set_nlink(inode, 1);
257 		inode->i_size = ent_oi->u.prop->length;
258 		break;
259 	}
260 
261 	return d_splice_alias(inode, dentry);
262 }
263 
264 static int openpromfs_readdir(struct file *file, struct dir_context *ctx)
265 {
266 	struct inode *inode = file_inode(file);
267 	struct op_inode_info *oi = OP_I(inode);
268 	struct device_node *dp = oi->u.node;
269 	struct device_node *child;
270 	struct property *prop;
271 	int i;
272 
273 	mutex_lock(&op_mutex);
274 
275 	if (ctx->pos == 0) {
276 		if (!dir_emit(ctx, ".", 1, inode->i_ino, DT_DIR))
277 			goto out;
278 		ctx->pos = 1;
279 	}
280 	if (ctx->pos == 1) {
281 		if (!dir_emit(ctx, "..", 2,
282 			    (dp->parent == NULL ?
283 			     OPENPROM_ROOT_INO :
284 			     dp->parent->unique_id), DT_DIR))
285 			goto out;
286 		ctx->pos = 2;
287 	}
288 	i = ctx->pos - 2;
289 
290 	/* First, the children nodes as directories.  */
291 	child = dp->child;
292 	while (i && child) {
293 		child = child->sibling;
294 		i--;
295 	}
296 	while (child) {
297 		if (!dir_emit(ctx,
298 			    kbasename(child->full_name),
299 			    strlen(kbasename(child->full_name)),
300 			    child->unique_id, DT_DIR))
301 			goto out;
302 
303 		ctx->pos++;
304 		child = child->sibling;
305 	}
306 
307 	/* Next, the properties as files.  */
308 	prop = dp->properties;
309 	while (i && prop) {
310 		prop = prop->next;
311 		i--;
312 	}
313 	while (prop) {
314 		if (!dir_emit(ctx, prop->name, strlen(prop->name),
315 			    prop->unique_id, DT_REG))
316 			goto out;
317 
318 		ctx->pos++;
319 		prop = prop->next;
320 	}
321 
322 out:
323 	mutex_unlock(&op_mutex);
324 	return 0;
325 }
326 
327 static struct kmem_cache *op_inode_cachep;
328 
329 static struct inode *openprom_alloc_inode(struct super_block *sb)
330 {
331 	struct op_inode_info *oi;
332 
333 	oi = kmem_cache_alloc(op_inode_cachep, GFP_KERNEL);
334 	if (!oi)
335 		return NULL;
336 
337 	return &oi->vfs_inode;
338 }
339 
340 static void openprom_free_inode(struct inode *inode)
341 {
342 	kmem_cache_free(op_inode_cachep, OP_I(inode));
343 }
344 
345 static struct inode *openprom_iget(struct super_block *sb, ino_t ino)
346 {
347 	struct inode *inode;
348 
349 	inode = iget_locked(sb, ino);
350 	if (!inode)
351 		return ERR_PTR(-ENOMEM);
352 	if (inode->i_state & I_NEW) {
353 		inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
354 		if (inode->i_ino == OPENPROM_ROOT_INO) {
355 			inode->i_op = &openprom_inode_operations;
356 			inode->i_fop = &openprom_operations;
357 			inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
358 		}
359 		unlock_new_inode(inode);
360 	}
361 	return inode;
362 }
363 
364 static int openprom_remount(struct super_block *sb, int *flags, char *data)
365 {
366 	sync_filesystem(sb);
367 	*flags |= SB_NOATIME;
368 	return 0;
369 }
370 
371 static const struct super_operations openprom_sops = {
372 	.alloc_inode	= openprom_alloc_inode,
373 	.free_inode	= openprom_free_inode,
374 	.statfs		= simple_statfs,
375 	.remount_fs	= openprom_remount,
376 };
377 
378 static int openprom_fill_super(struct super_block *s, void *data, int silent)
379 {
380 	struct inode *root_inode;
381 	struct op_inode_info *oi;
382 	int ret;
383 
384 	s->s_flags |= SB_NOATIME;
385 	s->s_blocksize = 1024;
386 	s->s_blocksize_bits = 10;
387 	s->s_magic = OPENPROM_SUPER_MAGIC;
388 	s->s_op = &openprom_sops;
389 	s->s_time_gran = 1;
390 	root_inode = openprom_iget(s, OPENPROM_ROOT_INO);
391 	if (IS_ERR(root_inode)) {
392 		ret = PTR_ERR(root_inode);
393 		goto out_no_root;
394 	}
395 
396 	oi = OP_I(root_inode);
397 	oi->type = op_inode_node;
398 	oi->u.node = of_find_node_by_path("/");
399 
400 	s->s_root = d_make_root(root_inode);
401 	if (!s->s_root)
402 		goto out_no_root_dentry;
403 	return 0;
404 
405 out_no_root_dentry:
406 	ret = -ENOMEM;
407 out_no_root:
408 	printk("openprom_fill_super: get root inode failed\n");
409 	return ret;
410 }
411 
412 static struct dentry *openprom_mount(struct file_system_type *fs_type,
413 	int flags, const char *dev_name, void *data)
414 {
415 	return mount_single(fs_type, flags, data, openprom_fill_super);
416 }
417 
418 static struct file_system_type openprom_fs_type = {
419 	.owner		= THIS_MODULE,
420 	.name		= "openpromfs",
421 	.mount		= openprom_mount,
422 	.kill_sb	= kill_anon_super,
423 };
424 MODULE_ALIAS_FS("openpromfs");
425 
426 static void op_inode_init_once(void *data)
427 {
428 	struct op_inode_info *oi = (struct op_inode_info *) data;
429 
430 	inode_init_once(&oi->vfs_inode);
431 }
432 
433 static int __init init_openprom_fs(void)
434 {
435 	int err;
436 
437 	op_inode_cachep = kmem_cache_create("op_inode_cache",
438 					    sizeof(struct op_inode_info),
439 					    0,
440 					    (SLAB_RECLAIM_ACCOUNT |
441 					     SLAB_MEM_SPREAD | SLAB_ACCOUNT),
442 					    op_inode_init_once);
443 	if (!op_inode_cachep)
444 		return -ENOMEM;
445 
446 	err = register_filesystem(&openprom_fs_type);
447 	if (err)
448 		kmem_cache_destroy(op_inode_cachep);
449 
450 	return err;
451 }
452 
453 static void __exit exit_openprom_fs(void)
454 {
455 	unregister_filesystem(&openprom_fs_type);
456 	/*
457 	 * Make sure all delayed rcu free inodes are flushed before we
458 	 * destroy cache.
459 	 */
460 	rcu_barrier();
461 	kmem_cache_destroy(op_inode_cachep);
462 }
463 
464 module_init(init_openprom_fs)
465 module_exit(exit_openprom_fs)
466 MODULE_LICENSE("GPL");
467