fs/openpromfs/inode.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* inode.c: /proc/openprom handling routines
0003  *
0004  * Copyright (C) 1996-1999 Jakub Jelinek  (jakub@redhat.com)
0005  * Copyright (C) 1998      Eddie C. Dost  (ecd@skynet.be)
0006  */
0007
0008 #include <linux/module.h>
0009 #include <linux/types.h>
0010 #include <linux/string.h>
0011 #include <linux/fs.h>
0012 #include <linux/fs_context.h>
0013 #include <linux/init.h>
0014 #include <linux/slab.h>
0015 #include <linux/seq_file.h>
0016 #include <linux/magic.h>
0017
0018 #include <asm/openprom.h>
0019 #include <asm/oplib.h>
0020 #include <asm/prom.h>
0021 #include <linux/uaccess.h>
0022
0023 static DEFINE_MUTEX(op_mutex);
0024
0025 #define OPENPROM_ROOT_INO   0
0026
0027 enum op_inode_type {
0028     op_inode_node,
0029     op_inode_prop,
0030 };
0031
0032 union op_inode_data {
0033     struct device_node  *node;
0034     struct property     *prop;
0035 };
0036
0037 struct op_inode_info {
0038     struct inode        vfs_inode;
0039     enum op_inode_type  type;
0040     union op_inode_data u;
0041 };
0042
0043 static struct inode *openprom_iget(struct super_block *sb, ino_t ino);
0044
0045 static inline struct op_inode_info *OP_I(struct inode *inode)
0046 {
0047     return container_of(inode, struct op_inode_info, vfs_inode);
0048 }
0049
0050 static int is_string(unsigned char *p, int len)
0051 {
0052     int i;
0053
0054     for (i = 0; i < len; i++) {
0055         unsigned char val = p[i];
0056
0057         if ((i && !val) ||
0058             (val >= ' ' && val <= '~'))
0059             continue;
0060
0061         return 0;
0062     }
0063
0064     return 1;
0065 }
0066
0067 static int property_show(struct seq_file *f, void *v)
0068 {
0069     struct property *prop = f->private;
0070     void *pval;
0071     int len;
0072
0073     len = prop->length;
0074     pval = prop->value;
0075
0076     if (is_string(pval, len)) {
0077         while (len > 0) {
0078             int n = strlen(pval);
0079
0080             seq_printf(f, "%s", (char *) pval);
0081
0082             /* Skip over the NULL byte too.  */
0083             pval += n + 1;
0084             len -= n + 1;
0085
0086             if (len > 0)
0087                 seq_printf(f, " + ");
0088         }
0089     } else {
0090         if (len & 3) {
0091             while (len) {
0092                 len--;
0093                 if (len)
0094                     seq_printf(f, "%02x.",
0095                            *(unsigned char *) pval);
0096                 else
0097                     seq_printf(f, "%02x",
0098                            *(unsigned char *) pval);
0099                 pval++;
0100             }
0101         } else {
0102             while (len >= 4) {
0103                 len -= 4;
0104
0105                 if (len)
0106                     seq_printf(f, "%08x.",
0107                            *(unsigned int *) pval);
0108                 else
0109                     seq_printf(f, "%08x",
0110                            *(unsigned int *) pval);
0111                 pval += 4;
0112             }
0113         }
0114     }
0115     seq_printf(f, "\n");
0116
0117     return 0;
0118 }
0119
0120 static void *property_start(struct seq_file *f, loff_t *pos)
0121 {
0122     if (*pos == 0)
0123         return pos;
0124     return NULL;
0125 }
0126
0127 static void *property_next(struct seq_file *f, void *v, loff_t *pos)
0128 {
0129     (*pos)++;
0130     return NULL;
0131 }
0132
0133 static void property_stop(struct seq_file *f, void *v)
0134 {
0135     /* Nothing to do */
0136 }
0137
0138 static const struct seq_operations property_op = {
0139     .start      = property_start,
0140     .next       = property_next,
0141     .stop       = property_stop,
0142     .show       = property_show
0143 };
0144
0145 static int property_open(struct inode *inode, struct file *file)
0146 {
0147     struct op_inode_info *oi = OP_I(inode);
0148     int ret;
0149
0150     BUG_ON(oi->type != op_inode_prop);
0151
0152     ret = seq_open(file, &property_op);
0153     if (!ret) {
0154         struct seq_file *m = file->private_data;
0155         m->private = oi->u.prop;
0156     }
0157     return ret;
0158 }
0159
0160 static const struct file_operations openpromfs_prop_ops = {
0161     .open       = property_open,
0162     .read       = seq_read,
0163     .llseek     = seq_lseek,
0164     .release    = seq_release,
0165 };
0166
0167 static int openpromfs_readdir(struct file *, struct dir_context *);
0168
0169 static const struct file_operations openprom_operations = {
0170     .read       = generic_read_dir,
0171     .iterate_shared = openpromfs_readdir,
0172     .llseek     = generic_file_llseek,
0173 };
0174
0175 static struct dentry *openpromfs_lookup(struct inode *, struct dentry *, unsigned int);
0176
0177 static const struct inode_operations openprom_inode_operations = {
0178     .lookup     = openpromfs_lookup,
0179 };
0180
0181 static struct dentry *openpromfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
0182 {
0183     struct op_inode_info *ent_oi, *oi = OP_I(dir);
0184     struct device_node *dp, *child;
0185     struct property *prop;
0186     enum op_inode_type ent_type;
0187     union op_inode_data ent_data;
0188     const char *name;
0189     struct inode *inode;
0190     unsigned int ino;
0191     int len;
0192
0193     BUG_ON(oi->type != op_inode_node);
0194
0195     dp = oi->u.node;
0196
0197     name = dentry->d_name.name;
0198     len = dentry->d_name.len;
0199
0200     mutex_lock(&op_mutex);
0201
0202     child = dp->child;
0203     while (child) {
0204         const char *node_name = kbasename(child->full_name);
0205         int n = strlen(node_name);
0206
0207         if (len == n &&
0208             !strncmp(node_name, name, len)) {
0209             ent_type = op_inode_node;
0210             ent_data.node = child;
0211             ino = child->unique_id;
0212             goto found;
0213         }
0214         child = child->sibling;
0215     }
0216
0217     prop = dp->properties;
0218     while (prop) {
0219         int n = strlen(prop->name);
0220
0221         if (len == n && !strncmp(prop->name, name, len)) {
0222             ent_type = op_inode_prop;
0223             ent_data.prop = prop;
0224             ino = prop->unique_id;
0225             goto found;
0226         }
0227
0228         prop = prop->next;
0229     }
0230
0231     mutex_unlock(&op_mutex);
0232     return ERR_PTR(-ENOENT);
0233
0234 found:
0235     inode = openprom_iget(dir->i_sb, ino);
0236     mutex_unlock(&op_mutex);
0237     if (IS_ERR(inode))
0238         return ERR_CAST(inode);
0239     if (inode->i_state & I_NEW) {
0240         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
0241         ent_oi = OP_I(inode);
0242         ent_oi->type = ent_type;
0243         ent_oi->u = ent_data;
0244
0245         switch (ent_type) {
0246         case op_inode_node:
0247             inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
0248             inode->i_op = &openprom_inode_operations;
0249             inode->i_fop = &openprom_operations;
0250             set_nlink(inode, 2);
0251             break;
0252         case op_inode_prop:
0253             if (of_node_name_eq(dp, "options") && (len == 17) &&
0254                 !strncmp (name, "security-password", 17))
0255                 inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
0256             else
0257                 inode->i_mode = S_IFREG | S_IRUGO;
0258             inode->i_fop = &openpromfs_prop_ops;
0259             set_nlink(inode, 1);
0260             inode->i_size = ent_oi->u.prop->length;
0261             break;
0262         }
0263         unlock_new_inode(inode);
0264     }
0265
0266     return d_splice_alias(inode, dentry);
0267 }
0268
0269 static int openpromfs_readdir(struct file *file, struct dir_context *ctx)
0270 {
0271     struct inode *inode = file_inode(file);
0272     struct op_inode_info *oi = OP_I(inode);
0273     struct device_node *dp = oi->u.node;
0274     struct device_node *child;
0275     struct property *prop;
0276     int i;
0277
0278     mutex_lock(&op_mutex);
0279
0280     if (ctx->pos == 0) {
0281         if (!dir_emit(ctx, ".", 1, inode->i_ino, DT_DIR))
0282             goto out;
0283         ctx->pos = 1;
0284     }
0285     if (ctx->pos == 1) {
0286         if (!dir_emit(ctx, "..", 2,
0287                 (dp->parent == NULL ?
0288                  OPENPROM_ROOT_INO :
0289                  dp->parent->unique_id), DT_DIR))
0290             goto out;
0291         ctx->pos = 2;
0292     }
0293     i = ctx->pos - 2;
0294
0295     /* First, the children nodes as directories.  */
0296     child = dp->child;
0297     while (i && child) {
0298         child = child->sibling;
0299         i--;
0300     }
0301     while (child) {
0302         if (!dir_emit(ctx,
0303                 kbasename(child->full_name),
0304                 strlen(kbasename(child->full_name)),
0305                 child->unique_id, DT_DIR))
0306             goto out;
0307
0308         ctx->pos++;
0309         child = child->sibling;
0310     }
0311
0312     /* Next, the properties as files.  */
0313     prop = dp->properties;
0314     while (i && prop) {
0315         prop = prop->next;
0316         i--;
0317     }
0318     while (prop) {
0319         if (!dir_emit(ctx, prop->name, strlen(prop->name),
0320                 prop->unique_id, DT_REG))
0321             goto out;
0322
0323         ctx->pos++;
0324         prop = prop->next;
0325     }
0326
0327 out:
0328     mutex_unlock(&op_mutex);
0329     return 0;
0330 }
0331
0332 static struct kmem_cache *op_inode_cachep;
0333
0334 static struct inode *openprom_alloc_inode(struct super_block *sb)
0335 {
0336     struct op_inode_info *oi;
0337
0338     oi = alloc_inode_sb(sb, op_inode_cachep, GFP_KERNEL);
0339     if (!oi)
0340         return NULL;
0341
0342     return &oi->vfs_inode;
0343 }
0344
0345 static void openprom_free_inode(struct inode *inode)
0346 {
0347     kmem_cache_free(op_inode_cachep, OP_I(inode));
0348 }
0349
0350 static struct inode *openprom_iget(struct super_block *sb, ino_t ino)
0351 {
0352     struct inode *inode = iget_locked(sb, ino);
0353     if (!inode)
0354         inode = ERR_PTR(-ENOMEM);
0355     return inode;
0356 }
0357
0358 static int openprom_remount(struct super_block *sb, int *flags, char *data)
0359 {
0360     sync_filesystem(sb);
0361     *flags |= SB_NOATIME;
0362     return 0;
0363 }
0364
0365 static const struct super_operations openprom_sops = {
0366     .alloc_inode    = openprom_alloc_inode,
0367     .free_inode = openprom_free_inode,
0368     .statfs     = simple_statfs,
0369     .remount_fs = openprom_remount,
0370 };
0371
0372 static int openprom_fill_super(struct super_block *s, struct fs_context *fc)
0373 {
0374     struct inode *root_inode;
0375     struct op_inode_info *oi;
0376     int ret;
0377
0378     s->s_flags |= SB_NOATIME;
0379     s->s_blocksize = 1024;
0380     s->s_blocksize_bits = 10;
0381     s->s_magic = OPENPROM_SUPER_MAGIC;
0382     s->s_op = &openprom_sops;
0383     s->s_time_gran = 1;
0384     root_inode = openprom_iget(s, OPENPROM_ROOT_INO);
0385     if (IS_ERR(root_inode)) {
0386         ret = PTR_ERR(root_inode);
0387         goto out_no_root;
0388     }
0389
0390     root_inode->i_mtime = root_inode->i_atime =
0391         root_inode->i_ctime = current_time(root_inode);
0392     root_inode->i_op = &openprom_inode_operations;
0393     root_inode->i_fop = &openprom_operations;
0394     root_inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
0395     oi = OP_I(root_inode);
0396     oi->type = op_inode_node;
0397     oi->u.node = of_find_node_by_path("/");
0398     unlock_new_inode(root_inode);
0399
0400     s->s_root = d_make_root(root_inode);
0401     if (!s->s_root)
0402         goto out_no_root_dentry;
0403     return 0;
0404
0405 out_no_root_dentry:
0406     ret = -ENOMEM;
0407 out_no_root:
0408     printk("openprom_fill_super: get root inode failed\n");
0409     return ret;
0410 }
0411
0412 static int openpromfs_get_tree(struct fs_context *fc)
0413 {
0414     return get_tree_single(fc, openprom_fill_super);
0415 }
0416
0417 static const struct fs_context_operations openpromfs_context_ops = {
0418     .get_tree   = openpromfs_get_tree,
0419 };
0420
0421 static int openpromfs_init_fs_context(struct fs_context *fc)
0422 {
0423     fc->ops = &openpromfs_context_ops;
0424     return 0;
0425 }
0426
0427 static struct file_system_type openprom_fs_type = {
0428     .owner      = THIS_MODULE,
0429     .name       = "openpromfs",
0430     .init_fs_context = openpromfs_init_fs_context,
0431     .kill_sb    = kill_anon_super,
0432 };
0433 MODULE_ALIAS_FS("openpromfs");
0434
0435 static void op_inode_init_once(void *data)
0436 {
0437     struct op_inode_info *oi = (struct op_inode_info *) data;
0438
0439     inode_init_once(&oi->vfs_inode);
0440 }
0441
0442 static int __init init_openprom_fs(void)
0443 {
0444     int err;
0445
0446     op_inode_cachep = kmem_cache_create("op_inode_cache",
0447                         sizeof(struct op_inode_info),
0448                         0,
0449                         (SLAB_RECLAIM_ACCOUNT |
0450                          SLAB_MEM_SPREAD | SLAB_ACCOUNT),
0451                         op_inode_init_once);
0452     if (!op_inode_cachep)
0453         return -ENOMEM;
0454
0455     err = register_filesystem(&openprom_fs_type);
0456     if (err)
0457         kmem_cache_destroy(op_inode_cachep);
0458
0459     return err;
0460 }
0461
0462 static void __exit exit_openprom_fs(void)
0463 {
0464     unregister_filesystem(&openprom_fs_type);
0465     /*
0466      * Make sure all delayed rcu free inodes are flushed before we
0467      * destroy cache.
0468      */
0469     rcu_barrier();
0470     kmem_cache_destroy(op_inode_cachep);
0471 }
0472
0473 module_init(init_openprom_fs)
0474 module_exit(exit_openprom_fs)
0475 MODULE_LICENSE("GPL");