Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
/*
 * Quota code necessary even when VFS quota support is not compiled
 * into the kernel.  The interesting stuff is over in dquot.c, here
 * we have symbols for initial quotactl(2) handling, the sysctl(2)
 * variables, etc - things needed even when quota support disabled.
 */

#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <asm/current.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/types.h>
#include <linux/writeback.h>

static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
				     qid_t id)
{
	switch (cmd) {
	/* these commands do not require any special privilegues */
	case Q_GETFMT:
	case Q_SYNC:
	case Q_GETINFO:
	case Q_XGETQSTAT:
	case Q_XGETQSTATV:
	case Q_XQUOTASYNC:
		break;
	/* allow to query information for dquots we "own" */
	case Q_GETQUOTA:
	case Q_XGETQUOTA:
		if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
		    (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
			break;
		/*FALLTHROUGH*/
	default:
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
	}

	return security_quotactl(cmd, type, id, sb);
}

static void quota_sync_one(struct super_block *sb, void *arg)
{
	if (sb->s_qcop && sb->s_qcop->quota_sync)
		sb->s_qcop->quota_sync(sb, *(int *)arg);
}

static int quota_sync_all(int type)
{
	int ret;

	if (type >= MAXQUOTAS)
		return -EINVAL;
	ret = security_quotactl(Q_SYNC, type, 0, NULL);
	if (!ret)
		iterate_supers(quota_sync_one, &type);
	return ret;
}

static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
		         struct path *path)
{
	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
		return -ENOSYS;
	if (sb->s_qcop->quota_on_meta)
		return sb->s_qcop->quota_on_meta(sb, type, id);
	if (IS_ERR(path))
		return PTR_ERR(path);
	return sb->s_qcop->quota_on(sb, type, id, path);
}

static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
{
	__u32 fmt;

	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
	if (!sb_has_quota_active(sb, type)) {
		mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
		return -ESRCH;
	}
	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
	if (copy_to_user(addr, &fmt, sizeof(fmt)))
		return -EFAULT;
	return 0;
}

static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
{
	struct if_dqinfo info;
	int ret;

	if (!sb->s_qcop->get_info)
		return -ENOSYS;
	ret = sb->s_qcop->get_info(sb, type, &info);
	if (!ret && copy_to_user(addr, &info, sizeof(info)))
		return -EFAULT;
	return ret;
}

static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
{
	struct if_dqinfo info;

	if (copy_from_user(&info, addr, sizeof(info)))
		return -EFAULT;
	if (!sb->s_qcop->set_info)
		return -ENOSYS;
	return sb->s_qcop->set_info(sb, type, &info);
}

static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
{
	memset(dst, 0, sizeof(*dst));
	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	dst->dqb_curspace = src->d_bcount;
	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	dst->dqb_isoftlimit = src->d_ino_softlimit;
	dst->dqb_curinodes = src->d_icount;
	dst->dqb_btime = src->d_btimer;
	dst->dqb_itime = src->d_itimer;
	dst->dqb_valid = QIF_ALL;
}

static int quota_getquota(struct super_block *sb, int type, qid_t id,
			  void __user *addr)
{
	struct kqid qid;
	struct fs_disk_quota fdq;
	struct if_dqblk idq;
	int ret;

	if (!sb->s_qcop->get_dqblk)
		return -ENOSYS;
	qid = make_kqid(current_user_ns(), type, id);
	if (!qid_valid(qid))
		return -EINVAL;
	ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
	if (ret)
		return ret;
	copy_to_if_dqblk(&idq, &fdq);
	if (copy_to_user(addr, &idq, sizeof(idq)))
		return -EFAULT;
	return 0;
}

static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
{
	dst->d_blk_hardlimit = src->dqb_bhardlimit;
	dst->d_blk_softlimit  = src->dqb_bsoftlimit;
	dst->d_bcount = src->dqb_curspace;
	dst->d_ino_hardlimit = src->dqb_ihardlimit;
	dst->d_ino_softlimit = src->dqb_isoftlimit;
	dst->d_icount = src->dqb_curinodes;
	dst->d_btimer = src->dqb_btime;
	dst->d_itimer = src->dqb_itime;

	dst->d_fieldmask = 0;
	if (src->dqb_valid & QIF_BLIMITS)
		dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
	if (src->dqb_valid & QIF_SPACE)
		dst->d_fieldmask |= FS_DQ_BCOUNT;
	if (src->dqb_valid & QIF_ILIMITS)
		dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
	if (src->dqb_valid & QIF_INODES)
		dst->d_fieldmask |= FS_DQ_ICOUNT;
	if (src->dqb_valid & QIF_BTIME)
		dst->d_fieldmask |= FS_DQ_BTIMER;
	if (src->dqb_valid & QIF_ITIME)
		dst->d_fieldmask |= FS_DQ_ITIMER;
}

static int quota_setquota(struct super_block *sb, int type, qid_t id,
			  void __user *addr)
{
	struct fs_disk_quota fdq;
	struct if_dqblk idq;
	struct kqid qid;

	if (copy_from_user(&idq, addr, sizeof(idq)))
		return -EFAULT;
	if (!sb->s_qcop->set_dqblk)
		return -ENOSYS;
	qid = make_kqid(current_user_ns(), type, id);
	if (!qid_valid(qid))
		return -EINVAL;
	copy_from_if_dqblk(&fdq, &idq);
	return sb->s_qcop->set_dqblk(sb, qid, &fdq);
}

static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
{
	__u32 flags;

	if (copy_from_user(&flags, addr, sizeof(flags)))
		return -EFAULT;
	if (!sb->s_qcop->set_xstate)
		return -ENOSYS;
	return sb->s_qcop->set_xstate(sb, flags, cmd);
}

static int quota_getxstate(struct super_block *sb, void __user *addr)
{
	struct fs_quota_stat fqs;
	int ret;

	if (!sb->s_qcop->get_xstate)
		return -ENOSYS;
	ret = sb->s_qcop->get_xstate(sb, &fqs);
	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
		return -EFAULT;
	return ret;
}

static int quota_getxstatev(struct super_block *sb, void __user *addr)
{
	struct fs_quota_statv fqs;
	int ret;

	if (!sb->s_qcop->get_xstatev)
		return -ENOSYS;

	memset(&fqs, 0, sizeof(fqs));
	if (copy_from_user(&fqs, addr, 1)) /* Just read qs_version */
		return -EFAULT;

	/* If this kernel doesn't support user specified version, fail */
	switch (fqs.qs_version) {
	case FS_QSTATV_VERSION1:
		break;
	default:
		return -EINVAL;
	}
	ret = sb->s_qcop->get_xstatev(sb, &fqs);
	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
		return -EFAULT;
	return ret;
}

static int quota_setxquota(struct super_block *sb, int type, qid_t id,
			   void __user *addr)
{
	struct fs_disk_quota fdq;
	struct kqid qid;

	if (copy_from_user(&fdq, addr, sizeof(fdq)))
		return -EFAULT;
	if (!sb->s_qcop->set_dqblk)
		return -ENOSYS;
	qid = make_kqid(current_user_ns(), type, id);
	if (!qid_valid(qid))
		return -EINVAL;
	return sb->s_qcop->set_dqblk(sb, qid, &fdq);
}

static int quota_getxquota(struct super_block *sb, int type, qid_t id,
			   void __user *addr)
{
	struct fs_disk_quota fdq;
	struct kqid qid;
	int ret;

	if (!sb->s_qcop->get_dqblk)
		return -ENOSYS;
	qid = make_kqid(current_user_ns(), type, id);
	if (!qid_valid(qid))
		return -EINVAL;
	ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
		return -EFAULT;
	return ret;
}

static int quota_rmxquota(struct super_block *sb, void __user *addr)
{
	__u32 flags;

	if (copy_from_user(&flags, addr, sizeof(flags)))
		return -EFAULT;
	if (!sb->s_qcop->rm_xquota)
		return -ENOSYS;
	return sb->s_qcop->rm_xquota(sb, flags);
}

/* Copy parameters and call proper function */
static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
		       void __user *addr, struct path *path)
{
	int ret;

	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
		return -EINVAL;
	if (!sb->s_qcop)
		return -ENOSYS;

	ret = check_quotactl_permission(sb, type, cmd, id);
	if (ret < 0)
		return ret;

	switch (cmd) {
	case Q_QUOTAON:
		return quota_quotaon(sb, type, cmd, id, path);
	case Q_QUOTAOFF:
		if (!sb->s_qcop->quota_off)
			return -ENOSYS;
		return sb->s_qcop->quota_off(sb, type);
	case Q_GETFMT:
		return quota_getfmt(sb, type, addr);
	case Q_GETINFO:
		return quota_getinfo(sb, type, addr);
	case Q_SETINFO:
		return quota_setinfo(sb, type, addr);
	case Q_GETQUOTA:
		return quota_getquota(sb, type, id, addr);
	case Q_SETQUOTA:
		return quota_setquota(sb, type, id, addr);
	case Q_SYNC:
		if (!sb->s_qcop->quota_sync)
			return -ENOSYS;
		return sb->s_qcop->quota_sync(sb, type);
	case Q_XQUOTAON:
	case Q_XQUOTAOFF:
		return quota_setxstate(sb, cmd, addr);
	case Q_XQUOTARM:
		return quota_rmxquota(sb, addr);
	case Q_XGETQSTAT:
		return quota_getxstate(sb, addr);
	case Q_XGETQSTATV:
		return quota_getxstatev(sb, addr);
	case Q_XSETQLIM:
		return quota_setxquota(sb, type, id, addr);
	case Q_XGETQUOTA:
		return quota_getxquota(sb, type, id, addr);
	case Q_XQUOTASYNC:
		if (sb->s_flags & MS_RDONLY)
			return -EROFS;
		/* XFS quotas are fully coherent now, making this call a noop */
		return 0;
	default:
		return -EINVAL;
	}
}

#ifdef CONFIG_BLOCK

/* Return 1 if 'cmd' will block on frozen filesystem */
static int quotactl_cmd_write(int cmd)
{
	switch (cmd) {
	case Q_GETFMT:
	case Q_GETINFO:
	case Q_SYNC:
	case Q_XGETQSTAT:
	case Q_XGETQSTATV:
	case Q_XGETQUOTA:
	case Q_XQUOTASYNC:
		return 0;
	}
	return 1;
}

#endif /* CONFIG_BLOCK */

/*
 * look up a superblock on which quota ops will be performed
 * - use the name of a block device to find the superblock thereon
 */
static struct super_block *quotactl_block(const char __user *special, int cmd)
{
#ifdef CONFIG_BLOCK
	struct block_device *bdev;
	struct super_block *sb;
	struct filename *tmp = getname(special);

	if (IS_ERR(tmp))
		return ERR_CAST(tmp);
	bdev = lookup_bdev(tmp->name);
	putname(tmp);
	if (IS_ERR(bdev))
		return ERR_CAST(bdev);
	if (quotactl_cmd_write(cmd))
		sb = get_super_thawed(bdev);
	else
		sb = get_super(bdev);
	bdput(bdev);
	if (!sb)
		return ERR_PTR(-ENODEV);

	return sb;
#else
	return ERR_PTR(-ENODEV);
#endif
}

/*
 * This is the system call interface. This communicates with
 * the user-level programs. Currently this only supports diskquota
 * calls. Maybe we need to add the process quotas etc. in the future,
 * but we probably should use rlimits for that.
 */
SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
		qid_t, id, void __user *, addr)
{
	uint cmds, type;
	struct super_block *sb = NULL;
	struct path path, *pathp = NULL;
	int ret;

	cmds = cmd >> SUBCMDSHIFT;
	type = cmd & SUBCMDMASK;

	/*
	 * As a special case Q_SYNC can be called without a specific device.
	 * It will iterate all superblocks that have quota enabled and call
	 * the sync action on each of them.
	 */
	if (!special) {
		if (cmds == Q_SYNC)
			return quota_sync_all(type);
		return -ENODEV;
	}

	/*
	 * Path for quotaon has to be resolved before grabbing superblock
	 * because that gets s_umount sem which is also possibly needed by path
	 * resolution (think about autofs) and thus deadlocks could arise.
	 */
	if (cmds == Q_QUOTAON) {
		ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
		if (ret)
			pathp = ERR_PTR(ret);
		else
			pathp = &path;
	}

	sb = quotactl_block(special, cmds);
	if (IS_ERR(sb)) {
		ret = PTR_ERR(sb);
		goto out;
	}

	ret = do_quotactl(sb, type, cmds, id, addr, pathp);

	drop_super(sb);
out:
	if (pathp && !IS_ERR(pathp))
		path_put(pathp);
	return ret;
}