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(dentry: 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(inode: d_inode(dentry: parent)); |
73 | if (simple_positive(dentry)) { |
74 | if (d_is_dir(dentry)) |
75 | simple_rmdir(d_inode(dentry: parent), dentry); |
76 | else |
77 | simple_unlink(d_inode(dentry: parent), dentry); |
78 | } |
79 | d_drop(dentry); |
80 | dput(dentry); |
81 | inode_unlock(inode: d_inode(dentry: 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(dentry: 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(inode: ret); |
105 | if (S_ISDIR(mode)) |
106 | set_nlink(inode: ret, nlink: 2); |
107 | } |
108 | return ret; |
109 | } |
110 | |
111 | static void hypfs_evict_inode(struct inode *inode) |
112 | { |
113 | clear_inode(inode); |
114 | kfree(objp: inode->i_private); |
115 | } |
116 | |
117 | static int hypfs_open(struct inode *inode, struct file *filp) |
118 | { |
119 | char *data = file_inode(f: 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(s: data, GFP_KERNEL); |
135 | if (!filp->private_data) { |
136 | mutex_unlock(lock: &fs_info->lock); |
137 | return -ENOMEM; |
138 | } |
139 | mutex_unlock(lock: &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(i: to)) |
155 | return 0; |
156 | count = copy_to_iter(addr: data + pos, bytes: available - pos, i: 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(f: iocb->ki_filp)->i_sb; |
168 | struct hypfs_sb_info *fs_info = sb->s_fs_info; |
169 | size_t count = iov_iter_count(i: 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(root: sb->s_root); |
187 | if (MACHINE_IS_VM) |
188 | rc = hypfs_vm_create_files(root: sb->s_root); |
189 | else |
190 | rc = hypfs_diag_create_files(root: sb->s_root); |
191 | if (rc) { |
192 | pr_err("Updating the hypfs tree failed\n" ); |
193 | hypfs_delete_tree(root: sb->s_root); |
194 | goto out; |
195 | } |
196 | hypfs_update_update(sb); |
197 | rc = count; |
198 | iov_iter_advance(i: from, bytes: count); |
199 | out: |
200 | mutex_unlock(lock: &fs_info->lock); |
201 | return rc; |
202 | } |
203 | |
204 | static int hypfs_release(struct inode *inode, struct file *filp) |
205 | { |
206 | kfree(objp: 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, desc: hypfs_fs_parameters, param, result: &result); |
227 | if (opt < 0) |
228 | return opt; |
229 | |
230 | switch (opt) { |
231 | case Opt_uid: |
232 | uid = make_kuid(current_user_ns(), uid: 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(), gid: 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(m: s, fmt: ",uid=%u" , from_kuid_munged(to: &init_user_ns, uid: hypfs_info->uid)); |
252 | seq_printf(m: s, fmt: ",gid=%u" , from_kgid_munged(to: &init_user_ns, gid: 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: root_dentry); |
278 | else |
279 | rc = hypfs_diag_create_files(root: root_dentry); |
280 | if (rc) |
281 | return rc; |
282 | update_file = hypfs_create_update_file(dir: root_dentry); |
283 | if (IS_ERR(ptr: update_file)) |
284 | return PTR_ERR(ptr: 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, fill_super: hypfs_fill_super); |
294 | } |
295 | |
296 | static void hypfs_free_fc(struct fs_context *fc) |
297 | { |
298 | kfree(objp: 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(size: 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(root: sb->s_root); |
330 | if (sb_info && sb_info->update_file) |
331 | hypfs_remove(dentry: sb_info->update_file); |
332 | kfree(objp: 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(inode: d_inode(dentry: parent)); |
344 | dentry = lookup_one_len(name, parent, strlen(name)); |
345 | if (IS_ERR(ptr: dentry)) { |
346 | dentry = ERR_PTR(error: -ENOMEM); |
347 | goto fail; |
348 | } |
349 | inode = hypfs_make_inode(sb: parent->d_sb, mode); |
350 | if (!inode) { |
351 | dput(dentry); |
352 | dentry = ERR_PTR(error: -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(inode: d_inode(dentry: parent)); |
365 | } else |
366 | BUG(); |
367 | inode->i_private = data; |
368 | d_instantiate(dentry, inode); |
369 | dget(dentry); |
370 | fail: |
371 | inode_unlock(inode: d_inode(dentry: 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(ptr: 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(parent: dir, name: "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(buf: tmp, TMP_SIZE, fmt: "%llu\n" , (unsigned long long int)value); |
408 | buffer = kstrdup(s: tmp, GFP_KERNEL); |
409 | if (!buffer) |
410 | return ERR_PTR(error: -ENOMEM); |
411 | dentry = |
412 | hypfs_create_file(parent: dir, name, data: buffer, S_IFREG | REG_FILE_MODE); |
413 | if (IS_ERR(ptr: dentry)) { |
414 | kfree(objp: buffer); |
415 | return ERR_PTR(error: -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(error: -ENOMEM); |
430 | sprintf(buf: buffer, fmt: "%s\n" , string); |
431 | dentry = |
432 | hypfs_create_file(parent: dir, name, data: buffer, S_IFREG | REG_FILE_MODE); |
433 | if (IS_ERR(ptr: dentry)) { |
434 | kfree(objp: buffer); |
435 | return ERR_PTR(error: -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(parent_kobj: hypervisor_kobj, name: "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(parent_kobj: hypervisor_kobj, name: "s390" ); |
476 | return rc; |
477 | } |
478 | |