xref: /openbmc/linux/fs/openpromfs/inode.c (revision b8265621) 
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/fs_context.h>
13 #include <linux/init.h>
14 #include <linux/slab.h>
15 #include <linux/seq_file.h>
16 #include <linux/magic.h>
17 
18 #include <asm/openprom.h>
19 #include <asm/oplib.h>
20 #include <asm/prom.h>
21 #include <linux/uaccess.h>
22 
23 static DEFINE_MUTEX(op_mutex);
24 
25 #define OPENPROM_ROOT_INO	0
26 
27 enum op_inode_type {
28 	op_inode_node,
29 	op_inode_prop,
30 };
31 
32 union op_inode_data {
33 	struct device_node	*node;
34 	struct property		*prop;
35 };
36 
37 struct op_inode_info {
38 	struct inode		vfs_inode;
39 	enum op_inode_type	type;
40 	union op_inode_data	u;
41 };
42 
43 static struct inode *openprom_iget(struct super_block *sb, ino_t ino);
44 
45 static inline struct op_inode_info *OP_I(struct inode *inode)
46 {
47 	return container_of(inode, struct op_inode_info, vfs_inode);
48 }
49 
50 static int is_string(unsigned char *p, int len)
51 {
52 	int i;
53 
54 	for (i = 0; i < len; i++) {
55 		unsigned char val = p[i];
56 
57 		if ((i && !val) ||
58 		    (val >= ' ' && val <= '~'))
59 			continue;
60 
61 		return 0;
62 	}
63 
64 	return 1;
65 }
66 
67 static int property_show(struct seq_file *f, void *v)
68 {
69 	struct property *prop = f->private;
70 	void *pval;
71 	int len;
72 
73 	len = prop->length;
74 	pval = prop->value;
75 
76 	if (is_string(pval, len)) {
77 		while (len > 0) {
78 			int n = strlen(pval);
79 
80 			seq_printf(f, "%s", (char *) pval);
81 
82 			/* Skip over the NULL byte too.  */
83 			pval += n + 1;
84 			len -= n + 1;
85 
86 			if (len > 0)
87 				seq_printf(f, " + ");
88 		}
89 	} else {
90 		if (len & 3) {
91 			while (len) {
92 				len--;
93 				if (len)
94 					seq_printf(f, "%02x.",
95 						   *(unsigned char *) pval);
96 				else
97 					seq_printf(f, "%02x",
98 						   *(unsigned char *) pval);
99 				pval++;
100 			}
101 		} else {
102 			while (len >= 4) {
103 				len -= 4;
104 
105 				if (len)
106 					seq_printf(f, "%08x.",
107 						   *(unsigned int *) pval);
108 				else
109 					seq_printf(f, "%08x",
110 						   *(unsigned int *) pval);
111 				pval += 4;
112 			}
113 		}
114 	}
115 	seq_printf(f, "\n");
116 
117 	return 0;
118 }
119 
120 static void *property_start(struct seq_file *f, loff_t *pos)
121 {
122 	if (*pos == 0)
123 		return pos;
124 	return NULL;
125 }
126 
127 static void *property_next(struct seq_file *f, void *v, loff_t *pos)
128 {
129 	(*pos)++;
130 	return NULL;
131 }
132 
133 static void property_stop(struct seq_file *f, void *v)
134 {
135 	/* Nothing to do */
136 }
137 
138 static const struct seq_operations property_op = {
139 	.start		= property_start,
140 	.next		= property_next,
141 	.stop		= property_stop,
142 	.show		= property_show
143 };
144 
145 static int property_open(struct inode *inode, struct file *file)
146 {
147 	struct op_inode_info *oi = OP_I(inode);
148 	int ret;
149 
150 	BUG_ON(oi->type != op_inode_prop);
151 
152 	ret = seq_open(file, &property_op);
153 	if (!ret) {
154 		struct seq_file *m = file->private_data;
155 		m->private = oi->u.prop;
156 	}
157 	return ret;
158 }
159 
160 static const struct file_operations openpromfs_prop_ops = {
161 	.open		= property_open,
162 	.read		= seq_read,
163 	.llseek		= seq_lseek,
164 	.release	= seq_release,
165 };
166 
167 static int openpromfs_readdir(struct file *, struct dir_context *);
168 
169 static const struct file_operations openprom_operations = {
170 	.read		= generic_read_dir,
171 	.iterate_shared	= openpromfs_readdir,
172 	.llseek		= generic_file_llseek,
173 };
174 
175 static struct dentry *openpromfs_lookup(struct inode *, struct dentry *, unsigned int);
176 
177 static const struct inode_operations openprom_inode_operations = {
178 	.lookup		= openpromfs_lookup,
179 };
180 
181 static struct dentry *openpromfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
182 {
183 	struct op_inode_info *ent_oi, *oi = OP_I(dir);
184 	struct device_node *dp, *child;
185 	struct property *prop;
186 	enum op_inode_type ent_type;
187 	union op_inode_data ent_data;
188 	const char *name;
189 	struct inode *inode;
190 	unsigned int ino;
191 	int len;
192 
193 	BUG_ON(oi->type != op_inode_node);
194 
195 	dp = oi->u.node;
196 
197 	name = dentry->d_name.name;
198 	len = dentry->d_name.len;
199 
200 	mutex_lock(&op_mutex);
201 
202 	child = dp->child;
203 	while (child) {
204 		const char *node_name = kbasename(child->full_name);
205 		int n = strlen(node_name);
206 
207 		if (len == n &&
208 		    !strncmp(node_name, name, len)) {
209 			ent_type = op_inode_node;
210 			ent_data.node = child;
211 			ino = child->unique_id;
212 			goto found;
213 		}
214 		child = child->sibling;
215 	}
216 
217 	prop = dp->properties;
218 	while (prop) {
219 		int n = strlen(prop->name);
220 
221 		if (len == n && !strncmp(prop->name, name, len)) {
222 			ent_type = op_inode_prop;
223 			ent_data.prop = prop;
224 			ino = prop->unique_id;
225 			goto found;
226 		}
227 
228 		prop = prop->next;
229 	}
230 
231 	mutex_unlock(&op_mutex);
232 	return ERR_PTR(-ENOENT);
233 
234 found:
235 	inode = openprom_iget(dir->i_sb, ino);
236 	mutex_unlock(&op_mutex);
237 	if (IS_ERR(inode))
238 		return ERR_CAST(inode);
239 	ent_oi = OP_I(inode);
240 	ent_oi->type = ent_type;
241 	ent_oi->u = ent_data;
242 
243 	switch (ent_type) {
244 	case op_inode_node:
245 		inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
246 		inode->i_op = &openprom_inode_operations;
247 		inode->i_fop = &openprom_operations;
248 		set_nlink(inode, 2);
249 		break;
250 	case op_inode_prop:
251 		if (of_node_name_eq(dp, "options") && (len == 17) &&
252 		    !strncmp (name, "security-password", 17))
253 			inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
254 		else
255 			inode->i_mode = S_IFREG | S_IRUGO;
256 		inode->i_fop = &openpromfs_prop_ops;
257 		set_nlink(inode, 1);
258 		inode->i_size = ent_oi->u.prop->length;
259 		break;
260 	}
261 
262 	return d_splice_alias(inode, dentry);
263 }
264 
265 static int openpromfs_readdir(struct file *file, struct dir_context *ctx)
266 {
267 	struct inode *inode = file_inode(file);
268 	struct op_inode_info *oi = OP_I(inode);
269 	struct device_node *dp = oi->u.node;
270 	struct device_node *child;
271 	struct property *prop;
272 	int i;
273 
274 	mutex_lock(&op_mutex);
275 
276 	if (ctx->pos == 0) {
277 		if (!dir_emit(ctx, ".", 1, inode->i_ino, DT_DIR))
278 			goto out;
279 		ctx->pos = 1;
280 	}
281 	if (ctx->pos == 1) {
282 		if (!dir_emit(ctx, "..", 2,
283 			    (dp->parent == NULL ?
284 			     OPENPROM_ROOT_INO :
285 			     dp->parent->unique_id), DT_DIR))
286 			goto out;
287 		ctx->pos = 2;
288 	}
289 	i = ctx->pos - 2;
290 
291 	/* First, the children nodes as directories.  */
292 	child = dp->child;
293 	while (i && child) {
294 		child = child->sibling;
295 		i--;
296 	}
297 	while (child) {
298 		if (!dir_emit(ctx,
299 			    kbasename(child->full_name),
300 			    strlen(kbasename(child->full_name)),
301 			    child->unique_id, DT_DIR))
302 			goto out;
303 
304 		ctx->pos++;
305 		child = child->sibling;
306 	}
307 
308 	/* Next, the properties as files.  */
309 	prop = dp->properties;
310 	while (i && prop) {
311 		prop = prop->next;
312 		i--;
313 	}
314 	while (prop) {
315 		if (!dir_emit(ctx, prop->name, strlen(prop->name),
316 			    prop->unique_id, DT_REG))
317 			goto out;
318 
319 		ctx->pos++;
320 		prop = prop->next;
321 	}
322 
323 out:
324 	mutex_unlock(&op_mutex);
325 	return 0;
326 }
327 
328 static struct kmem_cache *op_inode_cachep;
329 
330 static struct inode *openprom_alloc_inode(struct super_block *sb)
331 {
332 	struct op_inode_info *oi;
333 
334 	oi = kmem_cache_alloc(op_inode_cachep, GFP_KERNEL);
335 	if (!oi)
336 		return NULL;
337 
338 	return &oi->vfs_inode;
339 }
340 
341 static void openprom_free_inode(struct inode *inode)
342 {
343 	kmem_cache_free(op_inode_cachep, OP_I(inode));
344 }
345 
346 static struct inode *openprom_iget(struct super_block *sb, ino_t ino)
347 {
348 	struct inode *inode;
349 
350 	inode = iget_locked(sb, ino);
351 	if (!inode)
352 		return ERR_PTR(-ENOMEM);
353 	if (inode->i_state & I_NEW) {
354 		inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
355 		if (inode->i_ino == OPENPROM_ROOT_INO) {
356 			inode->i_op = &openprom_inode_operations;
357 			inode->i_fop = &openprom_operations;
358 			inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
359 		}
360 		unlock_new_inode(inode);
361 	}
362 	return inode;
363 }
364 
365 static int openprom_remount(struct super_block *sb, int *flags, char *data)
366 {
367 	sync_filesystem(sb);
368 	*flags |= SB_NOATIME;
369 	return 0;
370 }
371 
372 static const struct super_operations openprom_sops = {
373 	.alloc_inode	= openprom_alloc_inode,
374 	.free_inode	= openprom_free_inode,
375 	.statfs		= simple_statfs,
376 	.remount_fs	= openprom_remount,
377 };
378 
379 static int openprom_fill_super(struct super_block *s, struct fs_context *fc)
380 {
381 	struct inode *root_inode;
382 	struct op_inode_info *oi;
383 	int ret;
384 
385 	s->s_flags |= SB_NOATIME;
386 	s->s_blocksize = 1024;
387 	s->s_blocksize_bits = 10;
388 	s->s_magic = OPENPROM_SUPER_MAGIC;
389 	s->s_op = &openprom_sops;
390 	s->s_time_gran = 1;
391 	root_inode = openprom_iget(s, OPENPROM_ROOT_INO);
392 	if (IS_ERR(root_inode)) {
393 		ret = PTR_ERR(root_inode);
394 		goto out_no_root;
395 	}
396 
397 	oi = OP_I(root_inode);
398 	oi->type = op_inode_node;
399 	oi->u.node = of_find_node_by_path("/");
400 
401 	s->s_root = d_make_root(root_inode);
402 	if (!s->s_root)
403 		goto out_no_root_dentry;
404 	return 0;
405 
406 out_no_root_dentry:
407 	ret = -ENOMEM;
408 out_no_root:
409 	printk("openprom_fill_super: get root inode failed\n");
410 	return ret;
411 }
412 
413 static int openpromfs_get_tree(struct fs_context *fc)
414 {
415 	return get_tree_single(fc, openprom_fill_super);
416 }
417 
418 static const struct fs_context_operations openpromfs_context_ops = {
419 	.get_tree	= openpromfs_get_tree,
420 };
421 
422 static int openpromfs_init_fs_context(struct fs_context *fc)
423 {
424 	fc->ops = &openpromfs_context_ops;
425 	return 0;
426 }
427 
428 static struct file_system_type openprom_fs_type = {
429 	.owner		= THIS_MODULE,
430 	.name		= "openpromfs",
431 	.init_fs_context = openpromfs_init_fs_context,
432 	.kill_sb	= kill_anon_super,
433 };
434 MODULE_ALIAS_FS("openpromfs");
435 
436 static void op_inode_init_once(void *data)
437 {
438 	struct op_inode_info *oi = (struct op_inode_info *) data;
439 
440 	inode_init_once(&oi->vfs_inode);
441 }
442 
443 static int __init init_openprom_fs(void)
444 {
445 	int err;
446 
447 	op_inode_cachep = kmem_cache_create("op_inode_cache",
448 					    sizeof(struct op_inode_info),
449 					    0,
450 					    (SLAB_RECLAIM_ACCOUNT |
451 					     SLAB_MEM_SPREAD | SLAB_ACCOUNT),
452 					    op_inode_init_once);
453 	if (!op_inode_cachep)
454 		return -ENOMEM;
455 
456 	err = register_filesystem(&openprom_fs_type);
457 	if (err)
458 		kmem_cache_destroy(op_inode_cachep);
459 
460 	return err;
461 }
462 
463 static void __exit exit_openprom_fs(void)
464 {
465 	unregister_filesystem(&openprom_fs_type);
466 	/*
467 	 * Make sure all delayed rcu free inodes are flushed before we
468 	 * destroy cache.
469 	 */
470 	rcu_barrier();
471 	kmem_cache_destroy(op_inode_cachep);
472 }
473 
474 module_init(init_openprom_fs)
475 module_exit(exit_openprom_fs)
476 MODULE_LICENSE("GPL");
477