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/namei.h>
  16 #include <linux/vfs.h>
  17 #include <linux/slab.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/time.h>
  20 #include <linux/parser.h>
  21 #include <linux/sysfs.h>
  22 #include <linux/init.h>
  23 #include <linux/kobject.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/mount.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_delete(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, opt_err };
 211
 212 static const match_table_t hypfs_tokens = {
 213         {opt_uid, "uid=%u"},
 214         {opt_gid, "gid=%u"},
 215         {opt_err, NULL}
 216 };
 217
 218 static int hypfs_parse_options(char *options, struct super_block *sb)
 219 {
 220         char *str;
 221         substring_t args[MAX_OPT_ARGS];
 222         kuid_t uid;
 223         kgid_t gid;
 224
 225         if (!options)
 226                 return 0;
 227         while ((str = strsep(&options, ",")) != NULL) {
 228                 int token, option;
 229                 struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 230
 231                 if (!*str)
 232                         continue;
 233                 token = match_token(str, hypfs_tokens, args);
 234                 switch (token) {
 235                 case opt_uid:
 236                         if (match_int(&args[0], &option))
 237                                 return -EINVAL;
 238                         uid = make_kuid(current_user_ns(), option);
 239                         if (!uid_valid(uid))
 240                                 return -EINVAL;
 241                         hypfs_info->uid = uid;
 242                         break;
 243                 case opt_gid:
 244                         if (match_int(&args[0], &option))
 245                                 return -EINVAL;
 246                         gid = make_kgid(current_user_ns(), option);
 247                         if (!gid_valid(gid))
 248                                 return -EINVAL;
 249                         hypfs_info->gid = gid;
 250                         break;
 251                 case opt_err:
 252                 default:
 253                         pr_err("%s is not a valid mount option\n", str);
 254                         return -EINVAL;
 255                 }
 256         }
 257         return 0;
 258 }
 259
 260 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 261 {
 262         struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
 263
 264         seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 265         seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
 266         return 0;
 267 }
 268
 269 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
 270 {
 271         struct inode *root_inode;
 272         struct dentry *root_dentry;
 273         int rc = 0;
 274         struct hypfs_sb_info *sbi;
 275
 276         sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 277         if (!sbi)
 278                 return -ENOMEM;
 279         mutex_init(&sbi->lock);
 280         sbi->uid = current_uid();
 281         sbi->gid = current_gid();
 282         sb->s_fs_info = sbi;
 283         sb->s_blocksize = PAGE_SIZE;
 284         sb->s_blocksize_bits = PAGE_SHIFT;
 285         sb->s_magic = HYPFS_MAGIC;
 286         sb->s_op = &hypfs_s_ops;
 287         if (hypfs_parse_options(data, sb))
 288                 return -EINVAL;
 289         root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 290         if (!root_inode)
 291                 return -ENOMEM;
 292         root_inode->i_op = &simple_dir_inode_operations;
 293         root_inode->i_fop = &simple_dir_operations;
 294         sb->s_root = root_dentry = d_make_root(root_inode);
 295         if (!root_dentry)
 296                 return -ENOMEM;
 297         if (MACHINE_IS_VM)
 298                 rc = hypfs_vm_create_files(root_dentry);
 299         else
 300                 rc = hypfs_diag_create_files(root_dentry);
 301         if (rc)
 302                 return rc;
 303         sbi->update_file = hypfs_create_update_file(root_dentry);
 304         if (IS_ERR(sbi->update_file))
 305                 return PTR_ERR(sbi->update_file);
 306         hypfs_update_update(sb);
 307         pr_info("Hypervisor filesystem mounted\n");
 308         return 0;
 309 }
 310
 311 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
 312                         const char *devname, void *data)
 313 {
 314         return mount_single(fst, flags, data, hypfs_fill_super);
 315 }
 316
 317 static void hypfs_kill_super(struct super_block *sb)
 318 {
 319         struct hypfs_sb_info *sb_info = sb->s_fs_info;
 320
 321         if (sb->s_root)
 322                 hypfs_delete_tree(sb->s_root);
 323         if (sb_info && sb_info->update_file)
 324                 hypfs_remove(sb_info->update_file);
 325         kfree(sb->s_fs_info);
 326         sb->s_fs_info = NULL;
 327         kill_litter_super(sb);
 328 }
 329
 330 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 331                                         char *data, umode_t mode)
 332 {
 333         struct dentry *dentry;
 334         struct inode *inode;
 335
 336         inode_lock(d_inode(parent));
 337         dentry = lookup_one_len(name, parent, strlen(name));
 338         if (IS_ERR(dentry)) {
 339                 dentry = ERR_PTR(-ENOMEM);
 340                 goto fail;
 341         }
 342         inode = hypfs_make_inode(parent->d_sb, mode);
 343         if (!inode) {
 344                 dput(dentry);
 345                 dentry = ERR_PTR(-ENOMEM);
 346                 goto fail;
 347         }
 348         if (S_ISREG(mode)) {
 349                 inode->i_fop = &hypfs_file_ops;
 350                 if (data)
 351                         inode->i_size = strlen(data);
 352                 else
 353                         inode->i_size = 0;
 354         } else if (S_ISDIR(mode)) {
 355                 inode->i_op = &simple_dir_inode_operations;
 356                 inode->i_fop = &simple_dir_operations;
 357                 inc_nlink(d_inode(parent));
 358         } else
 359                 BUG();
 360         inode->i_private = data;
 361         d_instantiate(dentry, inode);
 362         dget(dentry);
 363 fail:
 364         inode_unlock(d_inode(parent));
 365         return dentry;
 366 }
 367
 368 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 369 {
 370         struct dentry *dentry;
 371
 372         dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 373         if (IS_ERR(dentry))
 374                 return dentry;
 375         hypfs_add_dentry(dentry);
 376         return dentry;
 377 }
 378
 379 static struct dentry *hypfs_create_update_file(struct dentry *dir)
 380 {
 381         struct dentry *dentry;
 382
 383         dentry = hypfs_create_file(dir, "update", NULL,
 384                                    S_IFREG | UPDATE_FILE_MODE);
 385         /*
 386          * We do not put the update file on the 'delete' list with
 387          * hypfs_add_dentry(), since it should not be removed when the tree
 388          * is updated.
 389          */
 390         return dentry;
 391 }
 392
 393 struct dentry *hypfs_create_u64(struct dentry *dir,
 394                                 const char *name, __u64 value)
 395 {
 396         char *buffer;
 397         char tmp[TMP_SIZE];
 398         struct dentry *dentry;
 399
 400         snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 401         buffer = kstrdup(tmp, GFP_KERNEL);
 402         if (!buffer)
 403                 return ERR_PTR(-ENOMEM);
 404         dentry =
 405             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 406         if (IS_ERR(dentry)) {
 407                 kfree(buffer);
 408                 return ERR_PTR(-ENOMEM);
 409         }
 410         hypfs_add_dentry(dentry);
 411         return dentry;
 412 }
 413
 414 struct dentry *hypfs_create_str(struct dentry *dir,
 415                                 const char *name, char *string)
 416 {
 417         char *buffer;
 418         struct dentry *dentry;
 419
 420         buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 421         if (!buffer)
 422                 return ERR_PTR(-ENOMEM);
 423         sprintf(buffer, "%s\n", string);
 424         dentry =
 425             hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 426         if (IS_ERR(dentry)) {
 427                 kfree(buffer);
 428                 return ERR_PTR(-ENOMEM);
 429         }
 430         hypfs_add_dentry(dentry);
 431         return dentry;
 432 }
 433
 434 static const struct file_operations hypfs_file_ops = {
 435         .open           = hypfs_open,
 436         .release        = hypfs_release,
 437         .read_iter      = hypfs_read_iter,
 438         .write_iter     = hypfs_write_iter,
 439         .llseek         = no_llseek,
 440 };
 441
 442 static struct file_system_type hypfs_type = {
 443         .owner          = THIS_MODULE,
 444         .name           = "s390_hypfs",
 445         .mount          = hypfs_mount,
 446         .kill_sb        = hypfs_kill_super
 447 };
 448
 449 static const struct super_operations hypfs_s_ops = {
 450         .statfs         = simple_statfs,
 451         .evict_inode    = hypfs_evict_inode,
 452         .show_options   = hypfs_show_options,
 453 };
 454
 455 static int __init hypfs_init(void)
 456 {
 457         int rc;
 458
 459         hypfs_dbfs_init();
 460
 461         if (hypfs_diag_init()) {
 462                 rc = -ENODATA;
 463                 goto fail_dbfs_exit;
 464         }
 465         if (hypfs_vm_init()) {
 466                 rc = -ENODATA;
 467                 goto fail_hypfs_diag_exit;
 468         }
 469         hypfs_sprp_init();
 470         if (hypfs_diag0c_init()) {
 471                 rc = -ENODATA;
 472                 goto fail_hypfs_sprp_exit;
 473         }
 474         rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 475         if (rc)
 476                 goto fail_hypfs_diag0c_exit;
 477         rc = register_filesystem(&hypfs_type);
 478         if (rc)
 479                 goto fail_filesystem;
 480         return 0;
 481
 482 fail_filesystem:
 483         sysfs_remove_mount_point(hypervisor_kobj, "s390");
 484 fail_hypfs_diag0c_exit:
 485         hypfs_diag0c_exit();
 486 fail_hypfs_sprp_exit:
 487         hypfs_sprp_exit();
 488         hypfs_vm_exit();
 489 fail_hypfs_diag_exit:
 490         hypfs_diag_exit();
 491 fail_dbfs_exit:
 492         hypfs_dbfs_exit();
 493         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 494         return rc;
 495 }
 496 device_initcall(hypfs_init)