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
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