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 pr_fmt(fmt) "hypfs: " fmt
 10
 11#include <linux/types.h>
 12#include <linux/errno.h>
 13#include <linux/fs.h>
 14#include <linux/fs_context.h>
 15#include <linux/fs_parser.h>
 16#include <linux/namei.h>
 17#include <linux/vfs.h>
 18#include <linux/slab.h>
 19#include <linux/pagemap.h>
 20#include <linux/time.h>
 21#include <linux/sysfs.h>
 22#include <linux/init.h>
 23#include <linux/kobject.h>
 24#include <linux/seq_file.h>
 25#include <linux/uio.h>
 26#include <asm/machine.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	if (IS_ROOT(dentry->d_parent)) {
 64		dentry->d_fsdata = hypfs_last_dentry;
 65		hypfs_last_dentry = dentry;
 66	}
 67}
 68
 69static void hypfs_delete_tree(void)
 70{
 71	while (hypfs_last_dentry) {
 72		struct dentry *next_dentry = hypfs_last_dentry->d_fsdata;
 73		simple_recursive_removal(hypfs_last_dentry, NULL);
 74		hypfs_last_dentry = next_dentry;
 75	}
 76}
 77
 78static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
 79{
 80	struct inode *ret = new_inode(sb);
 81
 82	if (ret) {
 83		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 84		ret->i_ino = get_next_ino();
 85		ret->i_mode = mode;
 86		ret->i_uid = hypfs_info->uid;
 87		ret->i_gid = hypfs_info->gid;
 88		simple_inode_init_ts(ret);
 89		if (S_ISDIR(mode))
 90			set_nlink(ret, 2);
 91	}
 92	return ret;
 93}
 94
 95static void hypfs_evict_inode(struct inode *inode)
 96{
 97	clear_inode(inode);
 98	kfree(inode->i_private);
 99}
100
101static int hypfs_open(struct inode *inode, struct file *filp)
102{
103	char *data = file_inode(filp)->i_private;
104	struct hypfs_sb_info *fs_info;
105
106	if (filp->f_mode & FMODE_WRITE) {
107		if (!(inode->i_mode & S_IWUGO))
108			return -EACCES;
109	}
110	if (filp->f_mode & FMODE_READ) {
111		if (!(inode->i_mode & S_IRUGO))
112			return -EACCES;
113	}
114
115	fs_info = inode->i_sb->s_fs_info;
116	if(data) {
117		mutex_lock(&fs_info->lock);
118		filp->private_data = kstrdup(data, GFP_KERNEL);
119		if (!filp->private_data) {
120			mutex_unlock(&fs_info->lock);
121			return -ENOMEM;
122		}
123		mutex_unlock(&fs_info->lock);
124	}
125	return nonseekable_open(inode, filp);
126}
127
128static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
129{
130	struct file *file = iocb->ki_filp;
131	char *data = file->private_data;
132	size_t available = strlen(data);
133	loff_t pos = iocb->ki_pos;
134	size_t count;
135
136	if (pos < 0)
137		return -EINVAL;
138	if (pos >= available || !iov_iter_count(to))
139		return 0;
140	count = copy_to_iter(data + pos, available - pos, to);
141	if (!count)
142		return -EFAULT;
143	iocb->ki_pos = pos + count;
144	file_accessed(file);
145	return count;
146}
147
148static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
149{
150	int rc;
151	struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
152	struct hypfs_sb_info *fs_info = sb->s_fs_info;
153	size_t count = iov_iter_count(from);
154
155	/*
156	 * Currently we only allow one update per second for two reasons:
157	 * 1. diag 204 is VERY expensive
158	 * 2. If several processes do updates in parallel and then read the
159	 *    hypfs data, the likelihood of collisions is reduced, if we restrict
160	 *    the minimum update interval. A collision occurs, if during the
161	 *    data gathering of one process another process triggers an update
162	 *    If the first process wants to ensure consistent data, it has
163	 *    to restart data collection in this case.
164	 */
165	mutex_lock(&fs_info->lock);
166	if (fs_info->last_update == ktime_get_seconds()) {
167		rc = -EBUSY;
168		goto out;
169	}
170	hypfs_delete_tree();
171	if (machine_is_vm())
172		rc = hypfs_vm_create_files(sb->s_root);
173	else
174		rc = hypfs_diag_create_files(sb->s_root);
175	if (rc) {
176		pr_err("Updating the hypfs tree failed\n");
177		hypfs_delete_tree();
178		goto out;
179	}
180	hypfs_update_update(sb);
181	rc = count;
182	iov_iter_advance(from, count);
183out:
184	mutex_unlock(&fs_info->lock);
185	return rc;
186}
187
188static int hypfs_release(struct inode *inode, struct file *filp)
189{
190	kfree(filp->private_data);
191	return 0;
192}
193
194enum { Opt_uid, Opt_gid, };
195
196static const struct fs_parameter_spec hypfs_fs_parameters[] = {
197	fsparam_u32("gid", Opt_gid),
198	fsparam_u32("uid", Opt_uid),
199	{}
200};
201
202static int hypfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
203{
204	struct hypfs_sb_info *hypfs_info = fc->s_fs_info;
205	struct fs_parse_result result;
206	kuid_t uid;
207	kgid_t gid;
208	int opt;
209
210	opt = fs_parse(fc, hypfs_fs_parameters, param, &result);
211	if (opt < 0)
212		return opt;
213
214	switch (opt) {
215	case Opt_uid:
216		uid = make_kuid(current_user_ns(), result.uint_32);
217		if (!uid_valid(uid))
218			return invalf(fc, "Unknown uid");
219		hypfs_info->uid = uid;
220		break;
221	case Opt_gid:
222		gid = make_kgid(current_user_ns(), result.uint_32);
223		if (!gid_valid(gid))
224			return invalf(fc, "Unknown gid");
225		hypfs_info->gid = gid;
226		break;
227	}
228	return 0;
229}
230
231static int hypfs_show_options(struct seq_file *s, struct dentry *root)
232{
233	struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
234
235	seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
236	seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
237	return 0;
238}
239
240static int hypfs_fill_super(struct super_block *sb, struct fs_context *fc)
241{
242	struct hypfs_sb_info *sbi = sb->s_fs_info;
243	struct inode *root_inode;
244	struct dentry *root_dentry, *update_file;
245	int rc;
246
247	sb->s_blocksize = PAGE_SIZE;
248	sb->s_blocksize_bits = PAGE_SHIFT;
249	sb->s_magic = HYPFS_MAGIC;
250	sb->s_op = &hypfs_s_ops;
251
252	root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
253	if (!root_inode)
254		return -ENOMEM;
255	root_inode->i_op = &simple_dir_inode_operations;
256	root_inode->i_fop = &simple_dir_operations;
257	sb->s_root = root_dentry = d_make_root(root_inode);
258	if (!root_dentry)
259		return -ENOMEM;
260	if (machine_is_vm())
261		rc = hypfs_vm_create_files(root_dentry);
262	else
263		rc = hypfs_diag_create_files(root_dentry);
264	if (rc)
265		return rc;
266	update_file = hypfs_create_update_file(root_dentry);
267	if (IS_ERR(update_file))
268		return PTR_ERR(update_file);
269	sbi->update_file = update_file;
270	hypfs_update_update(sb);
271	pr_info("Hypervisor filesystem mounted\n");
272	return 0;
273}
274
275static int hypfs_get_tree(struct fs_context *fc)
276{
277	return get_tree_single(fc, hypfs_fill_super);
278}
279
280static void hypfs_free_fc(struct fs_context *fc)
281{
282	kfree(fc->s_fs_info);
283}
284
285static const struct fs_context_operations hypfs_context_ops = {
286	.free		= hypfs_free_fc,
287	.parse_param	= hypfs_parse_param,
288	.get_tree	= hypfs_get_tree,
289};
290
291static int hypfs_init_fs_context(struct fs_context *fc)
292{
293	struct hypfs_sb_info *sbi;
294
295	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
296	if (!sbi)
297		return -ENOMEM;
298
299	mutex_init(&sbi->lock);
300	sbi->uid = current_uid();
301	sbi->gid = current_gid();
302
303	fc->s_fs_info = sbi;
304	fc->ops = &hypfs_context_ops;
305	return 0;
306}
307
308static void hypfs_kill_super(struct super_block *sb)
309{
310	struct hypfs_sb_info *sb_info = sb->s_fs_info;
311
312	hypfs_last_dentry = NULL;
313	kill_anon_super(sb);
314	kfree(sb_info);
315}
316
317static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
318					char *data, umode_t mode)
319{
320	struct dentry *dentry;
321	struct inode *inode;
322
323	dentry = simple_start_creating(parent, name);
324	if (IS_ERR(dentry))
325		return ERR_PTR(-ENOMEM);
326	inode = hypfs_make_inode(parent->d_sb, mode);
327	if (!inode) {
328		simple_done_creating(dentry);
329		return ERR_PTR(-ENOMEM);
330	}
331	if (S_ISREG(mode)) {
332		inode->i_fop = &hypfs_file_ops;
333		if (data)
334			inode->i_size = strlen(data);
335		else
336			inode->i_size = 0;
337	} else if (S_ISDIR(mode)) {
338		inode->i_op = &simple_dir_inode_operations;
339		inode->i_fop = &simple_dir_operations;
340		inc_nlink(d_inode(parent));
341	} else
342		BUG();
343	inode->i_private = data;
344	d_make_persistent(dentry, inode);
345	simple_done_creating(dentry);
346	return dentry;	 // borrowed
347}
348
349struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
350{
351	struct dentry *dentry;
352
353	dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
354	if (IS_ERR(dentry))
355		return dentry;
356	hypfs_add_dentry(dentry);
357	return dentry;
358}
359
360static struct dentry *hypfs_create_update_file(struct dentry *dir)
361{
362	struct dentry *dentry;
363
364	dentry = hypfs_create_file(dir, "update", NULL,
365				   S_IFREG | UPDATE_FILE_MODE);
366	/*
367	 * We do not put the update file on the 'delete' list with
368	 * hypfs_add_dentry(), since it should not be removed when the tree
369	 * is updated.
370	 */
371	return dentry;
372}
373
374int hypfs_create_u64(struct dentry *dir, const char *name, __u64 value)
375{
376	char *buffer;
377	char tmp[TMP_SIZE];
378	struct dentry *dentry;
379
380	snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
381	buffer = kstrdup(tmp, GFP_KERNEL);
382	if (!buffer)
383		return -ENOMEM;
384	dentry =
385	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
386	if (IS_ERR(dentry)) {
387		kfree(buffer);
388		return -ENOMEM;
389	}
390	hypfs_add_dentry(dentry);
391	return 0;
392}
393
394int hypfs_create_str(struct dentry *dir, const char *name, char *string)
395{
396	char *buffer;
397	struct dentry *dentry;
398
399	buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
400	if (!buffer)
401		return -ENOMEM;
402	sprintf(buffer, "%s\n", string);
403	dentry =
404	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
405	if (IS_ERR(dentry)) {
406		kfree(buffer);
407		return -ENOMEM;
408	}
409	hypfs_add_dentry(dentry);
410	return 0;
411}
412
413static const struct file_operations hypfs_file_ops = {
414	.open		= hypfs_open,
415	.release	= hypfs_release,
416	.read_iter	= hypfs_read_iter,
417	.write_iter	= hypfs_write_iter,
418};
419
420static struct file_system_type hypfs_type = {
421	.owner		= THIS_MODULE,
422	.name		= "s390_hypfs",
423	.init_fs_context = hypfs_init_fs_context,
424	.parameters	= hypfs_fs_parameters,
425	.kill_sb	= hypfs_kill_super
426};
427
428static const struct super_operations hypfs_s_ops = {
429	.statfs		= simple_statfs,
430	.evict_inode	= hypfs_evict_inode,
431	.show_options	= hypfs_show_options,
432};
433
434int __init __hypfs_fs_init(void)
435{
436	int rc;
437
438	rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
439	if (rc)
440		return rc;
441	rc = register_filesystem(&hypfs_type);
442	if (rc)
443		goto fail;
444	return 0;
445fail:
446	sysfs_remove_mount_point(hypervisor_kobj, "s390");
447	return rc;
448}