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
33static struct dentry *hypfs_create_update_file(struct dentry *dir);
34
35struct 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
43static const struct file_operations hypfs_file_ops;
44static struct file_system_type hypfs_type;
45static const struct super_operations hypfs_s_ops;
46
47/* start of list of all dentries, which have to be deleted on update */
48static struct dentry *hypfs_last_dentry;
49
50static 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
61static void hypfs_add_dentry(struct dentry *dentry)
62{
63	dentry->d_fsdata = hypfs_last_dentry;
64	hypfs_last_dentry = dentry;
65}
66
67static 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
84static 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
94static 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
111static void hypfs_evict_inode(struct inode *inode)
112{
113	clear_inode(inode);
114	kfree(inode->i_private);
115}
116
117static 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
144static 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
164static 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);
199out:
200	mutex_unlock(&fs_info->lock);
201	return rc;
202}
203
204static int hypfs_release(struct inode *inode, struct file *filp)
205{
206	kfree(filp->private_data);
207	return 0;
208}
209
210enum { Opt_uid, Opt_gid, };
211
212static const struct fs_parameter_spec hypfs_fs_parameters[] = {
213	fsparam_u32("gid", Opt_gid),
214	fsparam_u32("uid", Opt_uid),
215	{}
216};
217
218static 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
247static 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
256static 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
291static int hypfs_get_tree(struct fs_context *fc)
292{
293	return get_tree_single(fc, hypfs_fill_super);
294}
295
296static void hypfs_free_fc(struct fs_context *fc)
297{
298	kfree(fc->s_fs_info);
299}
300
301static 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
307static 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
324static 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
337static 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);
370fail:
371	inode_unlock(d_inode(parent));
372	return dentry;
373}
374
375struct 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
386static 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
400struct 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
421struct 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
441static 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
449static 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
457static 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
463int __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;
474fail:
475	sysfs_remove_mount_point(hypervisor_kobj, "s390");
476	return rc;
477}
478