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 simple_inode_init_ts(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 simple_inode_init_ts(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_fs_parameters[] = { 213 fsparam_u32("gid", Opt_gid), 214 fsparam_u32("uid", Opt_uid), 215 {} 216 }; 217 218 static int hypfs_parse_param(struct fs_context *fc, struct fs_parameter *param) 219 { 220 struct hypfs_sb_info *hypfs_info = fc->s_fs_info; 221 struct fs_parse_result result; 222 kuid_t uid; 223 kgid_t gid; 224 int opt; 225 226 opt = fs_parse(fc, hypfs_fs_parameters, param, &result); 227 if (opt < 0) 228 return opt; 229 230 switch (opt) { 231 case Opt_uid: 232 uid = make_kuid(current_user_ns(), result.uint_32); 233 if (!uid_valid(uid)) 234 return invalf(fc, "Unknown uid"); 235 hypfs_info->uid = uid; 236 break; 237 case Opt_gid: 238 gid = make_kgid(current_user_ns(), result.uint_32); 239 if (!gid_valid(gid)) 240 return invalf(fc, "Unknown gid"); 241 hypfs_info->gid = gid; 242 break; 243 } 244 return 0; 245 } 246 247 static int hypfs_show_options(struct seq_file *s, struct dentry *root) 248 { 249 struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info; 250 251 seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid)); 252 seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid)); 253 return 0; 254 } 255 256 static int hypfs_fill_super(struct super_block *sb, struct fs_context *fc) 257 { 258 struct hypfs_sb_info *sbi = sb->s_fs_info; 259 struct inode *root_inode; 260 struct dentry *root_dentry, *update_file; 261 int rc; 262 263 sb->s_blocksize = PAGE_SIZE; 264 sb->s_blocksize_bits = PAGE_SHIFT; 265 sb->s_magic = HYPFS_MAGIC; 266 sb->s_op = &hypfs_s_ops; 267 268 root_inode = hypfs_make_inode(sb, S_IFDIR | 0755); 269 if (!root_inode) 270 return -ENOMEM; 271 root_inode->i_op = &simple_dir_inode_operations; 272 root_inode->i_fop = &simple_dir_operations; 273 sb->s_root = root_dentry = d_make_root(root_inode); 274 if (!root_dentry) 275 return -ENOMEM; 276 if (MACHINE_IS_VM) 277 rc = hypfs_vm_create_files(root_dentry); 278 else 279 rc = hypfs_diag_create_files(root_dentry); 280 if (rc) 281 return rc; 282 update_file = hypfs_create_update_file(root_dentry); 283 if (IS_ERR(update_file)) 284 return PTR_ERR(update_file); 285 sbi->update_file = update_file; 286 hypfs_update_update(sb); 287 pr_info("Hypervisor filesystem mounted\n"); 288 return 0; 289 } 290 291 static int hypfs_get_tree(struct fs_context *fc) 292 { 293 return get_tree_single(fc, hypfs_fill_super); 294 } 295 296 static void hypfs_free_fc(struct fs_context *fc) 297 { 298 kfree(fc->s_fs_info); 299 } 300 301 static const struct fs_context_operations hypfs_context_ops = { 302 .free = hypfs_free_fc, 303 .parse_param = hypfs_parse_param, 304 .get_tree = hypfs_get_tree, 305 }; 306 307 static int hypfs_init_fs_context(struct fs_context *fc) 308 { 309 struct hypfs_sb_info *sbi; 310 311 sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL); 312 if (!sbi) 313 return -ENOMEM; 314 315 mutex_init(&sbi->lock); 316 sbi->uid = current_uid(); 317 sbi->gid = current_gid(); 318 319 fc->s_fs_info = sbi; 320 fc->ops = &hypfs_context_ops; 321 return 0; 322 } 323 324 static void hypfs_kill_super(struct super_block *sb) 325 { 326 struct hypfs_sb_info *sb_info = sb->s_fs_info; 327 328 if (sb->s_root) 329 hypfs_delete_tree(sb->s_root); 330 if (sb_info && sb_info->update_file) 331 hypfs_remove(sb_info->update_file); 332 kfree(sb->s_fs_info); 333 sb->s_fs_info = NULL; 334 kill_litter_super(sb); 335 } 336 337 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name, 338 char *data, umode_t mode) 339 { 340 struct dentry *dentry; 341 struct inode *inode; 342 343 inode_lock(d_inode(parent)); 344 dentry = lookup_one_len(name, parent, strlen(name)); 345 if (IS_ERR(dentry)) { 346 dentry = ERR_PTR(-ENOMEM); 347 goto fail; 348 } 349 inode = hypfs_make_inode(parent->d_sb, mode); 350 if (!inode) { 351 dput(dentry); 352 dentry = ERR_PTR(-ENOMEM); 353 goto fail; 354 } 355 if (S_ISREG(mode)) { 356 inode->i_fop = &hypfs_file_ops; 357 if (data) 358 inode->i_size = strlen(data); 359 else 360 inode->i_size = 0; 361 } else if (S_ISDIR(mode)) { 362 inode->i_op = &simple_dir_inode_operations; 363 inode->i_fop = &simple_dir_operations; 364 inc_nlink(d_inode(parent)); 365 } else 366 BUG(); 367 inode->i_private = data; 368 d_instantiate(dentry, inode); 369 dget(dentry); 370 fail: 371 inode_unlock(d_inode(parent)); 372 return dentry; 373 } 374 375 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name) 376 { 377 struct dentry *dentry; 378 379 dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE); 380 if (IS_ERR(dentry)) 381 return dentry; 382 hypfs_add_dentry(dentry); 383 return dentry; 384 } 385 386 static struct dentry *hypfs_create_update_file(struct dentry *dir) 387 { 388 struct dentry *dentry; 389 390 dentry = hypfs_create_file(dir, "update", NULL, 391 S_IFREG | UPDATE_FILE_MODE); 392 /* 393 * We do not put the update file on the 'delete' list with 394 * hypfs_add_dentry(), since it should not be removed when the tree 395 * is updated. 396 */ 397 return dentry; 398 } 399 400 struct dentry *hypfs_create_u64(struct dentry *dir, 401 const char *name, __u64 value) 402 { 403 char *buffer; 404 char tmp[TMP_SIZE]; 405 struct dentry *dentry; 406 407 snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value); 408 buffer = kstrdup(tmp, GFP_KERNEL); 409 if (!buffer) 410 return ERR_PTR(-ENOMEM); 411 dentry = 412 hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE); 413 if (IS_ERR(dentry)) { 414 kfree(buffer); 415 return ERR_PTR(-ENOMEM); 416 } 417 hypfs_add_dentry(dentry); 418 return dentry; 419 } 420 421 struct dentry *hypfs_create_str(struct dentry *dir, 422 const char *name, char *string) 423 { 424 char *buffer; 425 struct dentry *dentry; 426 427 buffer = kmalloc(strlen(string) + 2, GFP_KERNEL); 428 if (!buffer) 429 return ERR_PTR(-ENOMEM); 430 sprintf(buffer, "%s\n", string); 431 dentry = 432 hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE); 433 if (IS_ERR(dentry)) { 434 kfree(buffer); 435 return ERR_PTR(-ENOMEM); 436 } 437 hypfs_add_dentry(dentry); 438 return dentry; 439 } 440 441 static const struct file_operations hypfs_file_ops = { 442 .open = hypfs_open, 443 .release = hypfs_release, 444 .read_iter = hypfs_read_iter, 445 .write_iter = hypfs_write_iter, 446 .llseek = no_llseek, 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 } 478