arch/s390/hypfs/inode.c

   1 // SPDX-License-Identifier: GPL-1.0+
   2 /*
   3  *    Hypervisor filesystem for Linux on s390.
   4  *
   5  *    Copyright IBM Corp. 2006, 2008
   6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
   7  */
   8
   9 #define KMSG_COMPONENT "hypfs"
  10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  11
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/fs_context.h>
  16 #include <linux/fs_parser.h>
  17 #include <linux/namei.h>
  18 #include <linux/vfs.h>
  19 #include <linux/slab.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/time.h>
  22 #include <linux/sysfs.h>
  23 #include <linux/init.h>
  24 #include <linux/kobject.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/uio.h>
  27 #include <asm/ebcdic.h>
  28 #include "hypfs.h"
  29
  30 #define HYPFS_MAGIC 0x687970    /* ASCII 'hyp' */
  31 #define TMP_SIZE 64             /* size of temporary buffers */
  32
  33 static struct dentry *hypfs_create_update_file(struct dentry *dir);
  34
  35 struct hypfs_sb_info {
  36         kuid_t uid;                     /* uid used for files and dirs */
  37         kgid_t gid;                     /* gid used for files and dirs */
  38         struct dentry *update_file;     /* file to trigger update */
  39         time64_t last_update;           /* last update, CLOCK_MONOTONIC time */
  40         struct mutex lock;              /* lock to protect update process */
  41 };
  42
  43 static const struct file_operations hypfs_file_ops;
  44 static struct file_system_type hypfs_type;
  45 static const struct super_operations hypfs_s_ops;
  46
  47 /* start of list of all dentries, which have to be deleted on update */
  48 static struct dentry *hypfs_last_dentry;
  49
  50 static void hypfs_update_update(struct super_block *sb)
  51 {
  52         struct hypfs_sb_info *sb_info = sb->s_fs_info;
  53         struct inode *inode = d_inode(sb_info->update_file);
  54
  55         sb_info->last_update = ktime_get_seconds();
  56         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
  57 }
  58
  59 /* directory tree removal functions */
  60
  61 static void hypfs_add_dentry(struct dentry *dentry)
  62 {
  63         dentry->d_fsdata = hypfs_last_dentry;
  64         hypfs_last_dentry = dentry;
  65 }
  66
  67 static void hypfs_remove(struct dentry *dentry)
  68 {
  69         struct dentry *parent;
  70
  71         parent = dentry->d_parent;
  72         inode_lock(d_inode(parent));
  73         if (simple_positive(dentry)) {
  74                 if (d_is_dir(dentry))
  75                         simple_rmdir(d_inode(parent), dentry);
  76                 else
  77                         simple_unlink(d_inode(parent), dentry);
  78         }
  79         d_drop(dentry);
  80         dput(dentry);
  81         inode_unlock(d_inode(parent));
  82 }
  83
  84 static void hypfs_delete_tree(struct dentry *root)
  85 {
  86         while (hypfs_last_dentry) {
  87                 struct dentry *next_dentry;
  88                 next_dentry = hypfs_last_dentry->d_fsdata;
  89                 hypfs_remove(hypfs_last_dentry);
  90                 hypfs_last_dentry = next_dentry;
  91         }
  92 }
  93
  94 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
  95 {
  96         struct inode *ret = new_inode(sb);
  97
  98         if (ret) {
  99                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 100                 ret->i_ino = get_next_ino();
 101                 ret->i_mode = mode;
 102                 ret->i_uid = hypfs_info->uid;
 103                 ret->i_gid = hypfs_info->gid;
 104                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 105                 if (S_ISDIR(mode))
 106                         set_nlink(ret, 2);
 107         }
 108         return ret;
 109 }
 110
 111 static void hypfs_evict_inode(struct inode *inode)
 112 {
 113         clear_inode(inode);
 114         kfree(inode->i_private);
 115 }
 116
 117 static int hypfs_open(struct inode *inode, struct file *filp)
 118 {
 119         char *data = file_inode(filp)->i_private;
 120         struct hypfs_sb_info *fs_info;
 121
 122         if (filp->f_mode & FMODE_WRITE) {
 123                 if (!(inode->i_mode & S_IWUGO))
 124                         return -EACCES;
 125         }
 126         if (filp->f_mode & FMODE_READ) {
 127                 if (!(inode->i_mode & S_IRUGO))
 128                         return -EACCES;
 129         }
 130
 131         fs_info = inode->i_sb->s_fs_info;
 132         if(data) {
 133                 mutex_lock(&fs_info->lock);
 134                 filp->private_data = kstrdup(data, GFP_KERNEL);
 135                 if (!filp->private_data) {
 136                         mutex_unlock(&fs_info->lock);
 137                         return -ENOMEM;
 138                 }
 139                 mutex_unlock(&fs_info->lock);
 140         }
 141         return nonseekable_open(inode, filp);
 142 }
 143
 144 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 145 {
 146         struct file *file = iocb->ki_filp;
 147         char *data = file->private_data;
 148         size_t available = strlen(data);
 149         loff_t pos = iocb->ki_pos;
 150         size_t count;
 151
 152         if (pos < 0)
 153                 return -EINVAL;
 154         if (pos >= available || !iov_iter_count(to))
 155                 return 0;
 156         count = copy_to_iter(data + pos, available - pos, to);
 157         if (!count)
 158                 return -EFAULT;
 159         iocb->ki_pos = pos + count;
 160         file_accessed(file);
 161         return count;
 162 }
 163
 164 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 165 {
 166         int rc;
 167         struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 168         struct hypfs_sb_info *fs_info = sb->s_fs_info;
 169         size_t count = iov_iter_count(from);
 170
 171         /*
 172          * Currently we only allow one update per second for two reasons:
 173          * 1. diag 204 is VERY expensive
 174          * 2. If several processes do updates in parallel and then read the
 175          *    hypfs data, the likelihood of collisions is reduced, if we restrict
 176          *    the minimum update interval. A collision occurs, if during the
 177          *    data gathering of one process another process triggers an update
 178          *    If the first process wants to ensure consistent data, it has
 179          *    to restart data collection in this case.
 180          */
 181         mutex_lock(&fs_info->lock);
 182         if (fs_info->last_update == ktime_get_seconds()) {
 183                 rc = -EBUSY;
 184                 goto out;
 185         }
 186         hypfs_delete_tree(sb->s_root);
 187         if (MACHINE_IS_VM)
 188                 rc = hypfs_vm_create_files(sb->s_root);
 189         else
 190                 rc = hypfs_diag_create_files(sb->s_root);
 191         if (rc) {
 192                 pr_err("Updating the hypfs tree failed\n");
 193                 hypfs_delete_tree(sb->s_root);
 194                 goto out;
 195         }
 196         hypfs_update_update(sb);
 197         rc = count;
 198         iov_iter_advance(from, count);
 199 out:
 200         mutex_unlock(&fs_info->lock);
 201         return rc;
 202 }
 203
 204 static int hypfs_release(struct inode *inode, struct file *filp)
 205 {
 206         kfree(filp->private_data);
 207         return 0;
 208 }
 209
 210 enum { Opt_uid, Opt_gid, };
 211
 212 static const struct fs_parameter_spec hypfs_param_specs[] = {
 213         fsparam_u32("gid", Opt_gid),
 214         fsparam_u32("uid", Opt_uid),
 215         {}
 216 };
 217
 218 static const struct fs_parameter_description hypfs_fs_parameters = {
 219         .name           = "hypfs",
 220         .specs          = hypfs_param_specs,
 221 };
 222
 223 static int hypfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 224 {
 225         struct hypfs_sb_info *hypfs_info = fc->s_fs_info;
 226         struct fs_parse_result result;
 227         kuid_t uid;
 228         kgid_t gid;
 229         int opt;
 230
 231         opt = fs_parse(fc, &hypfs_fs_parameters, param, &result);
 232         if (opt < 0)
 233                 return opt;
 234
 235         switch (opt) {
 236         case Opt_uid:
 237                 uid = make_kuid(current_user_ns(), result.uint_32);
 238                 if (!uid_valid(uid))
 239                         return invalf(fc, "Unknown uid");
 240                 hypfs_info->uid = uid;
 241                 break;
 242         case Opt_gid:
 243                 gid = make_kgid(current_user_ns(), result.uint_32);
 244                 if (!gid_valid(gid))
 245                         return invalf(fc, "Unknown gid");
 246                 hypfs_info->gid = gid;
 247                 break;
 248         }
 249         return 0;
 250 }
 251
 252 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 253 {
 254         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 255
 256         seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 257         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
 258         return 0;
 259 }
 260
 261 static int hypfs_fill_super(struct super_block *sb, struct fs_context *fc)
 262 {
 263         struct hypfs_sb_info *sbi = sb->s_fs_info;
 264         struct inode *root_inode;
 265         struct dentry *root_dentry, *update_file;
 266         int rc;
 267
 268         sb->s_blocksize = PAGE_SIZE;
 269         sb->s_blocksize_bits = PAGE_SHIFT;
 270         sb->s_magic = HYPFS_MAGIC;
 271         sb->s_op = &hypfs_s_ops;
 272
 273         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 274         if (!root_inode)
 275                 return -ENOMEM;
 276         root_inode->i_op = &simple_dir_inode_operations;
 277         root_inode->i_fop = &simple_dir_operations;
 278         sb->s_root = root_dentry = d_make_root(root_inode);
 279         if (!root_dentry)
 280                 return -ENOMEM;
 281         if (MACHINE_IS_VM)
 282                 rc = hypfs_vm_create_files(root_dentry);
 283         else
 284                 rc = hypfs_diag_create_files(root_dentry);
 285         if (rc)
 286                 return rc;
 287         update_file = hypfs_create_update_file(root_dentry);
 288         if (IS_ERR(update_file))
 289                 return PTR_ERR(update_file);
 290         sbi->update_file = update_file;
 291         hypfs_update_update(sb);
 292         pr_info("Hypervisor filesystem mounted\n");
 293         return 0;
 294 }
 295
 296 static int hypfs_get_tree(struct fs_context *fc)
 297 {
 298         return get_tree_single(fc, hypfs_fill_super);
 299 }
 300
 301 static void hypfs_free_fc(struct fs_context *fc)
 302 {
 303         kfree(fc->s_fs_info);
 304 }
 305
 306 static const struct fs_context_operations hypfs_context_ops = {
 307         .free           = hypfs_free_fc,
 308         .parse_param    = hypfs_parse_param,
 309         .get_tree       = hypfs_get_tree,
 310 };
 311
 312 static int hypfs_init_fs_context(struct fs_context *fc)
 313 {
 314         struct hypfs_sb_info *sbi;
 315
 316         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 317         if (!sbi)
 318                 return -ENOMEM;
 319
 320         mutex_init(&sbi->lock);
 321         sbi->uid = current_uid();
 322         sbi->gid = current_gid();
 323
 324         fc->s_fs_info = sbi;
 325         fc->ops = &hypfs_context_ops;
 326         return 0;
 327 }
 328
 329 static void hypfs_kill_super(struct super_block *sb)
 330 {
 331         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 332
 333         if (sb->s_root)
 334                 hypfs_delete_tree(sb->s_root);
 335         if (sb_info && sb_info->update_file)
 336                 hypfs_remove(sb_info->update_file);
 337         kfree(sb->s_fs_info);
 338         sb->s_fs_info = NULL;
 339         kill_litter_super(sb);
 340 }
 341
 342 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 343                                         char *data, umode_t mode)
 344 {
 345         struct dentry *dentry;
 346         struct inode *inode;
 347
 348         inode_lock(d_inode(parent));
 349         dentry = lookup_one_len(name, parent, strlen(name));
 350         if (IS_ERR(dentry)) {
 351                 dentry = ERR_PTR(-ENOMEM);
 352                 goto fail;
 353         }
 354         inode = hypfs_make_inode(parent->d_sb, mode);
 355         if (!inode) {
 356                 dput(dentry);
 357                 dentry = ERR_PTR(-ENOMEM);
 358                 goto fail;
 359         }
 360         if (S_ISREG(mode)) {
 361                 inode->i_fop = &hypfs_file_ops;
 362                 if (data)
 363                         inode->i_size = strlen(data);
 364                 else
 365                         inode->i_size = 0;
 366         } else if (S_ISDIR(mode)) {
 367                 inode->i_op = &simple_dir_inode_operations;
 368                 inode->i_fop = &simple_dir_operations;
 369                 inc_nlink(d_inode(parent));
 370         } else
 371                 BUG();
 372         inode->i_private = data;
 373         d_instantiate(dentry, inode);
 374         dget(dentry);
 375 fail:
 376         inode_unlock(d_inode(parent));
 377         return dentry;
 378 }
 379
 380 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 381 {
 382         struct dentry *dentry;
 383
 384         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 385         if (IS_ERR(dentry))
 386                 return dentry;
 387         hypfs_add_dentry(dentry);
 388         return dentry;
 389 }
 390
 391 static struct dentry *hypfs_create_update_file(struct dentry *dir)
 392 {
 393         struct dentry *dentry;
 394
 395         dentry = hypfs_create_file(dir, "update", NULL,
 396                                    S_IFREG | UPDATE_FILE_MODE);
 397         /*
 398          * We do not put the update file on the 'delete' list with
 399          * hypfs_add_dentry(), since it should not be removed when the tree
 400          * is updated.
 401          */
 402         return dentry;
 403 }
 404
 405 struct dentry *hypfs_create_u64(struct dentry *dir,
 406                                 const char *name, __u64 value)
 407 {
 408         char *buffer;
 409         char tmp[TMP_SIZE];
 410         struct dentry *dentry;
 411
 412         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 413         buffer = kstrdup(tmp, GFP_KERNEL);
 414         if (!buffer)
 415                 return ERR_PTR(-ENOMEM);
 416         dentry =
 417             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 418         if (IS_ERR(dentry)) {
 419                 kfree(buffer);
 420                 return ERR_PTR(-ENOMEM);
 421         }
 422         hypfs_add_dentry(dentry);
 423         return dentry;
 424 }
 425
 426 struct dentry *hypfs_create_str(struct dentry *dir,
 427                                 const char *name, char *string)
 428 {
 429         char *buffer;
 430         struct dentry *dentry;
 431
 432         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 433         if (!buffer)
 434                 return ERR_PTR(-ENOMEM);
 435         sprintf(buffer, "%s\n", string);
 436         dentry =
 437             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 438         if (IS_ERR(dentry)) {
 439                 kfree(buffer);
 440                 return ERR_PTR(-ENOMEM);
 441         }
 442         hypfs_add_dentry(dentry);
 443         return dentry;
 444 }
 445
 446 static const struct file_operations hypfs_file_ops = {
 447         .open           = hypfs_open,
 448         .release        = hypfs_release,
 449         .read_iter      = hypfs_read_iter,
 450         .write_iter     = hypfs_write_iter,
 451         .llseek         = no_llseek,
 452 };
 453
 454 static struct file_system_type hypfs_type = {
 455         .owner          = THIS_MODULE,
 456         .name           = "s390_hypfs",
 457         .init_fs_context = hypfs_init_fs_context,
 458         .parameters     = &hypfs_fs_parameters,
 459         .kill_sb        = hypfs_kill_super
 460 };
 461
 462 static const struct super_operations hypfs_s_ops = {
 463         .statfs         = simple_statfs,
 464         .evict_inode    = hypfs_evict_inode,
 465         .show_options   = hypfs_show_options,
 466 };
 467
 468 static int __init hypfs_init(void)
 469 {
 470         int rc;
 471
 472         hypfs_dbfs_init();
 473
 474         if (hypfs_diag_init()) {
 475                 rc = -ENODATA;
 476                 goto fail_dbfs_exit;
 477         }
 478         if (hypfs_vm_init()) {
 479                 rc = -ENODATA;
 480                 goto fail_hypfs_diag_exit;
 481         }
 482         hypfs_sprp_init();
 483         if (hypfs_diag0c_init()) {
 484                 rc = -ENODATA;
 485                 goto fail_hypfs_sprp_exit;
 486         }
 487         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 488         if (rc)
 489                 goto fail_hypfs_diag0c_exit;
 490         rc = register_filesystem(&hypfs_type);
 491         if (rc)
 492                 goto fail_filesystem;
 493         return 0;
 494
 495 fail_filesystem:
 496         sysfs_remove_mount_point(hypervisor_kobj, "s390");
 497 fail_hypfs_diag0c_exit:
 498         hypfs_diag0c_exit();
 499 fail_hypfs_sprp_exit:
 500         hypfs_sprp_exit();
 501         hypfs_vm_exit();
 502 fail_hypfs_diag_exit:
 503         hypfs_diag_exit();
 504 fail_dbfs_exit:
 505         hypfs_dbfs_exit();
 506         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 507         return rc;
 508 }
 509 device_initcall(hypfs_init)