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