Root/fs/quota/quota.c

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

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