1 /*
2 * Quota code necessary even when VFS quota support is not compiled
3 * into the kernel. The interesting stuff is over in dquot.c, here
4 * we have symbols for initial quotactl(2) handling, the sysctl(2)
5 * variables, etc - things needed even when quota support disabled.
6 */
7
8 #include <linux/fs.h>
9 #include <linux/namei.h>
10 #include <linux/slab.h>
11 #include <asm/current.h>
12 #include <asm/uaccess.h>
13 #include <linux/kernel.h>
14 #include <linux/security.h>
15 #include <linux/syscalls.h>
16 #include <linux/capability.h>
17 #include <linux/quotaops.h>
18 #include <linux/types.h>
19 #include <linux/writeback.h>
20
check_quotactl_permission(struct super_block * sb,int type,int cmd,qid_t id)21 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
22 qid_t id)
23 {
24 switch (cmd) {
25 /* these commands do not require any special privilegues */
26 case Q_GETFMT:
27 case Q_SYNC:
28 case Q_GETINFO:
29 case Q_XGETQSTAT:
30 case Q_XQUOTASYNC:
31 break;
32 /* allow to query information for dquots we "own" */
33 case Q_GETQUOTA:
34 case Q_XGETQUOTA:
35 if ((type == USRQUOTA && current_euid() == id) ||
36 (type == GRPQUOTA && in_egroup_p(id)))
37 break;
38 /*FALLTHROUGH*/
39 default:
40 if (!capable(CAP_SYS_ADMIN))
41 return -EPERM;
42 }
43
44 return security_quotactl(cmd, type, id, sb);
45 }
46
quota_sync_one(struct super_block * sb,void * arg)47 static void quota_sync_one(struct super_block *sb, void *arg)
48 {
49 if (sb->s_qcop && sb->s_qcop->quota_sync)
50 sb->s_qcop->quota_sync(sb, *(int *)arg, 1);
51 }
52
quota_sync_all(int type)53 static int quota_sync_all(int type)
54 {
55 int ret;
56
57 if (type >= MAXQUOTAS)
58 return -EINVAL;
59 ret = security_quotactl(Q_SYNC, type, 0, NULL);
60 if (!ret)
61 iterate_supers(quota_sync_one, &type);
62 return ret;
63 }
64
quota_quotaon(struct super_block * sb,int type,int cmd,qid_t id,struct path * path)65 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
66 struct path *path)
67 {
68 if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
69 return -ENOSYS;
70 if (sb->s_qcop->quota_on_meta)
71 return sb->s_qcop->quota_on_meta(sb, type, id);
72 if (IS_ERR(path))
73 return PTR_ERR(path);
74 return sb->s_qcop->quota_on(sb, type, id, path);
75 }
76
quota_getfmt(struct super_block * sb,int type,void __user * addr)77 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
78 {
79 __u32 fmt;
80
81 down_read(&sb_dqopt(sb)->dqptr_sem);
82 if (!sb_has_quota_active(sb, type)) {
83 up_read(&sb_dqopt(sb)->dqptr_sem);
84 return -ESRCH;
85 }
86 fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
87 up_read(&sb_dqopt(sb)->dqptr_sem);
88 if (copy_to_user(addr, &fmt, sizeof(fmt)))
89 return -EFAULT;
90 return 0;
91 }
92
quota_getinfo(struct super_block * sb,int type,void __user * addr)93 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
94 {
95 struct if_dqinfo info;
96 int ret;
97
98 if (!sb->s_qcop->get_info)
99 return -ENOSYS;
100 ret = sb->s_qcop->get_info(sb, type, &info);
101 if (!ret && copy_to_user(addr, &info, sizeof(info)))
102 return -EFAULT;
103 return ret;
104 }
105
quota_setinfo(struct super_block * sb,int type,void __user * addr)106 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
107 {
108 struct if_dqinfo info;
109
110 if (copy_from_user(&info, addr, sizeof(info)))
111 return -EFAULT;
112 if (!sb->s_qcop->set_info)
113 return -ENOSYS;
114 return sb->s_qcop->set_info(sb, type, &info);
115 }
116
copy_to_if_dqblk(struct if_dqblk * dst,struct fs_disk_quota * src)117 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
118 {
119 dst->dqb_bhardlimit = src->d_blk_hardlimit;
120 dst->dqb_bsoftlimit = src->d_blk_softlimit;
121 dst->dqb_curspace = src->d_bcount;
122 dst->dqb_ihardlimit = src->d_ino_hardlimit;
123 dst->dqb_isoftlimit = src->d_ino_softlimit;
124 dst->dqb_curinodes = src->d_icount;
125 dst->dqb_btime = src->d_btimer;
126 dst->dqb_itime = src->d_itimer;
127 dst->dqb_valid = QIF_ALL;
128 }
129
quota_getquota(struct super_block * sb,int type,qid_t id,void __user * addr)130 static int quota_getquota(struct super_block *sb, int type, qid_t id,
131 void __user *addr)
132 {
133 struct fs_disk_quota fdq;
134 struct if_dqblk idq;
135 int ret;
136
137 if (!sb->s_qcop->get_dqblk)
138 return -ENOSYS;
139 ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
140 if (ret)
141 return ret;
142 copy_to_if_dqblk(&idq, &fdq);
143 if (copy_to_user(addr, &idq, sizeof(idq)))
144 return -EFAULT;
145 return 0;
146 }
147
copy_from_if_dqblk(struct fs_disk_quota * dst,struct if_dqblk * src)148 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
149 {
150 dst->d_blk_hardlimit = src->dqb_bhardlimit;
151 dst->d_blk_softlimit = src->dqb_bsoftlimit;
152 dst->d_bcount = src->dqb_curspace;
153 dst->d_ino_hardlimit = src->dqb_ihardlimit;
154 dst->d_ino_softlimit = src->dqb_isoftlimit;
155 dst->d_icount = src->dqb_curinodes;
156 dst->d_btimer = src->dqb_btime;
157 dst->d_itimer = src->dqb_itime;
158
159 dst->d_fieldmask = 0;
160 if (src->dqb_valid & QIF_BLIMITS)
161 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
162 if (src->dqb_valid & QIF_SPACE)
163 dst->d_fieldmask |= FS_DQ_BCOUNT;
164 if (src->dqb_valid & QIF_ILIMITS)
165 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
166 if (src->dqb_valid & QIF_INODES)
167 dst->d_fieldmask |= FS_DQ_ICOUNT;
168 if (src->dqb_valid & QIF_BTIME)
169 dst->d_fieldmask |= FS_DQ_BTIMER;
170 if (src->dqb_valid & QIF_ITIME)
171 dst->d_fieldmask |= FS_DQ_ITIMER;
172 }
173
quota_setquota(struct super_block * sb,int type,qid_t id,void __user * addr)174 static int quota_setquota(struct super_block *sb, int type, qid_t id,
175 void __user *addr)
176 {
177 struct fs_disk_quota fdq;
178 struct if_dqblk idq;
179
180 if (copy_from_user(&idq, addr, sizeof(idq)))
181 return -EFAULT;
182 if (!sb->s_qcop->set_dqblk)
183 return -ENOSYS;
184 copy_from_if_dqblk(&fdq, &idq);
185 return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
186 }
187
quota_setxstate(struct super_block * sb,int cmd,void __user * addr)188 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
189 {
190 __u32 flags;
191
192 if (copy_from_user(&flags, addr, sizeof(flags)))
193 return -EFAULT;
194 if (!sb->s_qcop->set_xstate)
195 return -ENOSYS;
196 return sb->s_qcop->set_xstate(sb, flags, cmd);
197 }
198
quota_getxstate(struct super_block * sb,void __user * addr)199 static int quota_getxstate(struct super_block *sb, void __user *addr)
200 {
201 struct fs_quota_stat fqs;
202 int ret;
203
204 if (!sb->s_qcop->get_xstate)
205 return -ENOSYS;
206 ret = sb->s_qcop->get_xstate(sb, &fqs);
207 if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
208 return -EFAULT;
209 return ret;
210 }
211
quota_setxquota(struct super_block * sb,int type,qid_t id,void __user * addr)212 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
213 void __user *addr)
214 {
215 struct fs_disk_quota fdq;
216
217 if (copy_from_user(&fdq, addr, sizeof(fdq)))
218 return -EFAULT;
219 if (!sb->s_qcop->set_dqblk)
220 return -ENOSYS;
221 return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
222 }
223
quota_getxquota(struct super_block * sb,int type,qid_t id,void __user * addr)224 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
225 void __user *addr)
226 {
227 struct fs_disk_quota fdq;
228 int ret;
229
230 if (!sb->s_qcop->get_dqblk)
231 return -ENOSYS;
232 ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
233 if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
234 return -EFAULT;
235 return ret;
236 }
237
238 /* Copy parameters and call proper function */
do_quotactl(struct super_block * sb,int type,int cmd,qid_t id,void __user * addr,struct path * path)239 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
240 void __user *addr, struct path *path)
241 {
242 int ret;
243
244 if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
245 return -EINVAL;
246 if (!sb->s_qcop)
247 return -ENOSYS;
248
249 ret = check_quotactl_permission(sb, type, cmd, id);
250 if (ret < 0)
251 return ret;
252
253 switch (cmd) {
254 case Q_QUOTAON:
255 return quota_quotaon(sb, type, cmd, id, path);
256 case Q_QUOTAOFF:
257 if (!sb->s_qcop->quota_off)
258 return -ENOSYS;
259 return sb->s_qcop->quota_off(sb, type);
260 case Q_GETFMT:
261 return quota_getfmt(sb, type, addr);
262 case Q_GETINFO:
263 return quota_getinfo(sb, type, addr);
264 case Q_SETINFO:
265 return quota_setinfo(sb, type, addr);
266 case Q_GETQUOTA:
267 return quota_getquota(sb, type, id, addr);
268 case Q_SETQUOTA:
269 return quota_setquota(sb, type, id, addr);
270 case Q_SYNC:
271 if (!sb->s_qcop->quota_sync)
272 return -ENOSYS;
273 return sb->s_qcop->quota_sync(sb, type, 1);
274 case Q_XQUOTAON:
275 case Q_XQUOTAOFF:
276 case Q_XQUOTARM:
277 return quota_setxstate(sb, cmd, addr);
278 case Q_XGETQSTAT:
279 return quota_getxstate(sb, addr);
280 case Q_XSETQLIM:
281 return quota_setxquota(sb, type, id, addr);
282 case Q_XGETQUOTA:
283 return quota_getxquota(sb, type, id, addr);
284 case Q_XQUOTASYNC:
285 if (sb->s_flags & MS_RDONLY)
286 return -EROFS;
287 /* XFS quotas are fully coherent now, making this call a noop */
288 return 0;
289 default:
290 return -EINVAL;
291 }
292 }
293
294 /* Return 1 if 'cmd' will block on frozen filesystem */
quotactl_cmd_write(int cmd)295 static int quotactl_cmd_write(int cmd)
296 {
297 switch (cmd) {
298 case Q_GETFMT:
299 case Q_GETINFO:
300 case Q_SYNC:
301 case Q_XGETQSTAT:
302 case Q_XGETQUOTA:
303 case Q_XQUOTASYNC:
304 return 0;
305 }
306 return 1;
307 }
308
309 /*
310 * look up a superblock on which quota ops will be performed
311 * - use the name of a block device to find the superblock thereon
312 */
quotactl_block(const char __user * special,int cmd)313 static struct super_block *quotactl_block(const char __user *special, int cmd)
314 {
315 #ifdef CONFIG_BLOCK
316 struct block_device *bdev;
317 struct super_block *sb;
318 char *tmp = getname(special);
319
320 if (IS_ERR(tmp))
321 return ERR_CAST(tmp);
322 bdev = lookup_bdev(tmp);
323 putname(tmp);
324 if (IS_ERR(bdev))
325 return ERR_CAST(bdev);
326 if (quotactl_cmd_write(cmd))
327 sb = get_super_thawed(bdev);
328 else
329 sb = get_super(bdev);
330 bdput(bdev);
331 if (!sb)
332 return ERR_PTR(-ENODEV);
333
334 return sb;
335 #else
336 return ERR_PTR(-ENODEV);
337 #endif
338 }
339
340 /*
341 * This is the system call interface. This communicates with
342 * the user-level programs. Currently this only supports diskquota
343 * calls. Maybe we need to add the process quotas etc. in the future,
344 * but we probably should use rlimits for that.
345 */
SYSCALL_DEFINE4(quotactl,unsigned int,cmd,const char __user *,special,qid_t,id,void __user *,addr)346 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
347 qid_t, id, void __user *, addr)
348 {
349 uint cmds, type;
350 struct super_block *sb = NULL;
351 struct path path, *pathp = NULL;
352 int ret;
353
354 cmds = cmd >> SUBCMDSHIFT;
355 type = cmd & SUBCMDMASK;
356
357 /*
358 * As a special case Q_SYNC can be called without a specific device.
359 * It will iterate all superblocks that have quota enabled and call
360 * the sync action on each of them.
361 */
362 if (!special) {
363 if (cmds == Q_SYNC)
364 return quota_sync_all(type);
365 return -ENODEV;
366 }
367
368 /*
369 * Path for quotaon has to be resolved before grabbing superblock
370 * because that gets s_umount sem which is also possibly needed by path
371 * resolution (think about autofs) and thus deadlocks could arise.
372 */
373 if (cmds == Q_QUOTAON) {
374 ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
375 if (ret)
376 pathp = ERR_PTR(ret);
377 else
378 pathp = &path;
379 }
380
381 sb = quotactl_block(special, cmds);
382 if (IS_ERR(sb)) {
383 ret = PTR_ERR(sb);
384 goto out;
385 }
386
387 ret = do_quotactl(sb, type, cmds, id, addr, pathp);
388
389 drop_super(sb);
390 out:
391 if (pathp && !IS_ERR(pathp))
392 path_put(pathp);
393 return ret;
394 }
395