Root/fs/ioctl.c

1/*
2 * linux/fs/ioctl.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/syscalls.h>
8#include <linux/mm.h>
9#include <linux/smp_lock.h>
10#include <linux/capability.h>
11#include <linux/file.h>
12#include <linux/fs.h>
13#include <linux/security.h>
14#include <linux/module.h>
15#include <linux/uaccess.h>
16#include <linux/writeback.h>
17#include <linux/buffer_head.h>
18#include <linux/falloc.h>
19
20#include <asm/ioctls.h>
21
22/* So that the fiemap access checks can't overflow on 32 bit machines. */
23#define FIEMAP_MAX_EXTENTS (UINT_MAX / sizeof(struct fiemap_extent))
24
25/**
26 * vfs_ioctl - call filesystem specific ioctl methods
27 * @filp: open file to invoke ioctl method on
28 * @cmd: ioctl command to execute
29 * @arg: command-specific argument for ioctl
30 *
31 * Invokes filesystem specific ->unlocked_ioctl, if one exists; otherwise
32 * invokes filesystem specific ->ioctl method. If neither method exists,
33 * returns -ENOTTY.
34 *
35 * Returns 0 on success, -errno on error.
36 */
37static long vfs_ioctl(struct file *filp, unsigned int cmd,
38              unsigned long arg)
39{
40    int error = -ENOTTY;
41
42    if (!filp->f_op)
43        goto out;
44
45    if (filp->f_op->unlocked_ioctl) {
46        error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
47        if (error == -ENOIOCTLCMD)
48            error = -EINVAL;
49        goto out;
50    } else if (filp->f_op->ioctl) {
51        lock_kernel();
52        error = filp->f_op->ioctl(filp->f_path.dentry->d_inode,
53                      filp, cmd, arg);
54        unlock_kernel();
55    }
56
57 out:
58    return error;
59}
60
61static int ioctl_fibmap(struct file *filp, int __user *p)
62{
63    struct address_space *mapping = filp->f_mapping;
64    int res, block;
65
66    /* do we support this mess? */
67    if (!mapping->a_ops->bmap)
68        return -EINVAL;
69    if (!capable(CAP_SYS_RAWIO))
70        return -EPERM;
71    res = get_user(block, p);
72    if (res)
73        return res;
74    res = mapping->a_ops->bmap(mapping, block);
75    return put_user(res, p);
76}
77
78/**
79 * fiemap_fill_next_extent - Fiemap helper function
80 * @fieinfo: Fiemap context passed into ->fiemap
81 * @logical: Extent logical start offset, in bytes
82 * @phys: Extent physical start offset, in bytes
83 * @len: Extent length, in bytes
84 * @flags: FIEMAP_EXTENT flags that describe this extent
85 *
86 * Called from file system ->fiemap callback. Will populate extent
87 * info as passed in via arguments and copy to user memory. On
88 * success, extent count on fieinfo is incremented.
89 *
90 * Returns 0 on success, -errno on error, 1 if this was the last
91 * extent that will fit in user array.
92 */
93#define SET_UNKNOWN_FLAGS (FIEMAP_EXTENT_DELALLOC)
94#define SET_NO_UNMOUNTED_IO_FLAGS (FIEMAP_EXTENT_DATA_ENCRYPTED)
95#define SET_NOT_ALIGNED_FLAGS (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
96int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
97                u64 phys, u64 len, u32 flags)
98{
99    struct fiemap_extent extent;
100    struct fiemap_extent *dest = fieinfo->fi_extents_start;
101
102    /* only count the extents */
103    if (fieinfo->fi_extents_max == 0) {
104        fieinfo->fi_extents_mapped++;
105        return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
106    }
107
108    if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
109        return 1;
110
111    if (flags & SET_UNKNOWN_FLAGS)
112        flags |= FIEMAP_EXTENT_UNKNOWN;
113    if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
114        flags |= FIEMAP_EXTENT_ENCODED;
115    if (flags & SET_NOT_ALIGNED_FLAGS)
116        flags |= FIEMAP_EXTENT_NOT_ALIGNED;
117
118    memset(&extent, 0, sizeof(extent));
119    extent.fe_logical = logical;
120    extent.fe_physical = phys;
121    extent.fe_length = len;
122    extent.fe_flags = flags;
123
124    dest += fieinfo->fi_extents_mapped;
125    if (copy_to_user(dest, &extent, sizeof(extent)))
126        return -EFAULT;
127
128    fieinfo->fi_extents_mapped++;
129    if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
130        return 1;
131    return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
132}
133EXPORT_SYMBOL(fiemap_fill_next_extent);
134
135/**
136 * fiemap_check_flags - check validity of requested flags for fiemap
137 * @fieinfo: Fiemap context passed into ->fiemap
138 * @fs_flags: Set of fiemap flags that the file system understands
139 *
140 * Called from file system ->fiemap callback. This will compute the
141 * intersection of valid fiemap flags and those that the fs supports. That
142 * value is then compared against the user supplied flags. In case of bad user
143 * flags, the invalid values will be written into the fieinfo structure, and
144 * -EBADR is returned, which tells ioctl_fiemap() to return those values to
145 * userspace. For this reason, a return code of -EBADR should be preserved.
146 *
147 * Returns 0 on success, -EBADR on bad flags.
148 */
149int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
150{
151    u32 incompat_flags;
152
153    incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
154    if (incompat_flags) {
155        fieinfo->fi_flags = incompat_flags;
156        return -EBADR;
157    }
158    return 0;
159}
160EXPORT_SYMBOL(fiemap_check_flags);
161
162static int fiemap_check_ranges(struct super_block *sb,
163                   u64 start, u64 len, u64 *new_len)
164{
165    *new_len = len;
166
167    if (len == 0)
168        return -EINVAL;
169
170    if (start > sb->s_maxbytes)
171        return -EFBIG;
172
173    /*
174     * Shrink request scope to what the fs can actually handle.
175     */
176    if ((len > sb->s_maxbytes) ||
177        (sb->s_maxbytes - len) < start)
178        *new_len = sb->s_maxbytes - start;
179
180    return 0;
181}
182
183static int ioctl_fiemap(struct file *filp, unsigned long arg)
184{
185    struct fiemap fiemap;
186    struct fiemap_extent_info fieinfo = { 0, };
187    struct inode *inode = filp->f_path.dentry->d_inode;
188    struct super_block *sb = inode->i_sb;
189    u64 len;
190    int error;
191
192    if (!inode->i_op->fiemap)
193        return -EOPNOTSUPP;
194
195    if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
196               sizeof(struct fiemap)))
197        return -EFAULT;
198
199    if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
200        return -EINVAL;
201
202    error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
203                    &len);
204    if (error)
205        return error;
206
207    fieinfo.fi_flags = fiemap.fm_flags;
208    fieinfo.fi_extents_max = fiemap.fm_extent_count;
209    fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
210
211    if (fiemap.fm_extent_count != 0 &&
212        !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
213               fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
214        return -EFAULT;
215
216    if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
217        filemap_write_and_wait(inode->i_mapping);
218
219    error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
220    fiemap.fm_flags = fieinfo.fi_flags;
221    fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
222    if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
223        error = -EFAULT;
224
225    return error;
226}
227
228#ifdef CONFIG_BLOCK
229
230#define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
231#define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
232
233/**
234 * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
235 * @inode - the inode to map
236 * @arg - the pointer to userspace where we copy everything to
237 * @get_block - the fs's get_block function
238 *
239 * This does FIEMAP for block based inodes. Basically it will just loop
240 * through get_block until we hit the number of extents we want to map, or we
241 * go past the end of the file and hit a hole.
242 *
243 * If it is possible to have data blocks beyond a hole past @inode->i_size, then
244 * please do not use this function, it will stop at the first unmapped block
245 * beyond i_size.
246 *
247 * If you use this function directly, you need to do your own locking. Use
248 * generic_block_fiemap if you want the locking done for you.
249 */
250
251int __generic_block_fiemap(struct inode *inode,
252               struct fiemap_extent_info *fieinfo, u64 start,
253               u64 len, get_block_t *get_block)
254{
255    struct buffer_head tmp;
256    unsigned int start_blk;
257    long long length = 0, map_len = 0;
258    u64 logical = 0, phys = 0, size = 0;
259    u32 flags = FIEMAP_EXTENT_MERGED;
260    int ret = 0, past_eof = 0, whole_file = 0;
261
262    if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
263        return ret;
264
265    start_blk = logical_to_blk(inode, start);
266
267    length = (long long)min_t(u64, len, i_size_read(inode));
268    if (length < len)
269        whole_file = 1;
270
271    map_len = length;
272
273    do {
274        /*
275         * we set b_size to the total size we want so it will map as
276         * many contiguous blocks as possible at once
277         */
278        memset(&tmp, 0, sizeof(struct buffer_head));
279        tmp.b_size = map_len;
280
281        ret = get_block(inode, start_blk, &tmp, 0);
282        if (ret)
283            break;
284
285        /* HOLE */
286        if (!buffer_mapped(&tmp)) {
287            length -= blk_to_logical(inode, 1);
288            start_blk++;
289
290            /*
291             * we want to handle the case where there is an
292             * allocated block at the front of the file, and then
293             * nothing but holes up to the end of the file properly,
294             * to make sure that extent at the front gets properly
295             * marked with FIEMAP_EXTENT_LAST
296             */
297            if (!past_eof &&
298                blk_to_logical(inode, start_blk) >=
299                blk_to_logical(inode, 0)+i_size_read(inode))
300                past_eof = 1;
301
302            /*
303             * first hole after going past the EOF, this is our
304             * last extent
305             */
306            if (past_eof && size) {
307                flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
308                ret = fiemap_fill_next_extent(fieinfo, logical,
309                                  phys, size,
310                                  flags);
311                break;
312            }
313
314            /* if we have holes up to/past EOF then we're done */
315            if (length <= 0 || past_eof)
316                break;
317        } else {
318            /*
319             * we have gone over the length of what we wanted to
320             * map, and it wasn't the entire file, so add the extent
321             * we got last time and exit.
322             *
323             * This is for the case where say we want to map all the
324             * way up to the second to the last block in a file, but
325             * the last block is a hole, making the second to last
326             * block FIEMAP_EXTENT_LAST. In this case we want to
327             * see if there is a hole after the second to last block
328             * so we can mark it properly. If we found data after
329             * we exceeded the length we were requesting, then we
330             * are good to go, just add the extent to the fieinfo
331             * and break
332             */
333            if (length <= 0 && !whole_file) {
334                ret = fiemap_fill_next_extent(fieinfo, logical,
335                                  phys, size,
336                                  flags);
337                break;
338            }
339
340            /*
341             * if size != 0 then we know we already have an extent
342             * to add, so add it.
343             */
344            if (size) {
345                ret = fiemap_fill_next_extent(fieinfo, logical,
346                                  phys, size,
347                                  flags);
348                if (ret)
349                    break;
350            }
351
352            logical = blk_to_logical(inode, start_blk);
353            phys = blk_to_logical(inode, tmp.b_blocknr);
354            size = tmp.b_size;
355            flags = FIEMAP_EXTENT_MERGED;
356
357            length -= tmp.b_size;
358            start_blk += logical_to_blk(inode, size);
359
360            /*
361             * If we are past the EOF, then we need to make sure as
362             * soon as we find a hole that the last extent we found
363             * is marked with FIEMAP_EXTENT_LAST
364             */
365            if (!past_eof &&
366                logical+size >=
367                blk_to_logical(inode, 0)+i_size_read(inode))
368                past_eof = 1;
369        }
370        cond_resched();
371    } while (1);
372
373    /* if ret is 1 then we just hit the end of the extent array */
374    if (ret == 1)
375        ret = 0;
376
377    return ret;
378}
379EXPORT_SYMBOL(__generic_block_fiemap);
380
381/**
382 * generic_block_fiemap - FIEMAP for block based inodes
383 * @inode: The inode to map
384 * @fieinfo: The mapping information
385 * @start: The initial block to map
386 * @len: The length of the extect to attempt to map
387 * @get_block: The block mapping function for the fs
388 *
389 * Calls __generic_block_fiemap to map the inode, after taking
390 * the inode's mutex lock.
391 */
392
393int generic_block_fiemap(struct inode *inode,
394             struct fiemap_extent_info *fieinfo, u64 start,
395             u64 len, get_block_t *get_block)
396{
397    int ret;
398    mutex_lock(&inode->i_mutex);
399    ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
400    mutex_unlock(&inode->i_mutex);
401    return ret;
402}
403EXPORT_SYMBOL(generic_block_fiemap);
404
405#endif /* CONFIG_BLOCK */
406
407/*
408 * This provides compatibility with legacy XFS pre-allocation ioctls
409 * which predate the fallocate syscall.
410 *
411 * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
412 * are used here, rest are ignored.
413 */
414int ioctl_preallocate(struct file *filp, void __user *argp)
415{
416    struct inode *inode = filp->f_path.dentry->d_inode;
417    struct space_resv sr;
418
419    if (copy_from_user(&sr, argp, sizeof(sr)))
420        return -EFAULT;
421
422    switch (sr.l_whence) {
423    case SEEK_SET:
424        break;
425    case SEEK_CUR:
426        sr.l_start += filp->f_pos;
427        break;
428    case SEEK_END:
429        sr.l_start += i_size_read(inode);
430        break;
431    default:
432        return -EINVAL;
433    }
434
435    return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
436}
437
438static int file_ioctl(struct file *filp, unsigned int cmd,
439        unsigned long arg)
440{
441    struct inode *inode = filp->f_path.dentry->d_inode;
442    int __user *p = (int __user *)arg;
443
444    switch (cmd) {
445    case FIBMAP:
446        return ioctl_fibmap(filp, p);
447    case FIONREAD:
448        return put_user(i_size_read(inode) - filp->f_pos, p);
449    case FS_IOC_RESVSP:
450    case FS_IOC_RESVSP64:
451        return ioctl_preallocate(filp, p);
452    }
453
454    return vfs_ioctl(filp, cmd, arg);
455}
456
457static int ioctl_fionbio(struct file *filp, int __user *argp)
458{
459    unsigned int flag;
460    int on, error;
461
462    error = get_user(on, argp);
463    if (error)
464        return error;
465    flag = O_NONBLOCK;
466#ifdef __sparc__
467    /* SunOS compatibility item. */
468    if (O_NONBLOCK != O_NDELAY)
469        flag |= O_NDELAY;
470#endif
471    spin_lock(&filp->f_lock);
472    if (on)
473        filp->f_flags |= flag;
474    else
475        filp->f_flags &= ~flag;
476    spin_unlock(&filp->f_lock);
477    return error;
478}
479
480static int ioctl_fioasync(unsigned int fd, struct file *filp,
481              int __user *argp)
482{
483    unsigned int flag;
484    int on, error;
485
486    error = get_user(on, argp);
487    if (error)
488        return error;
489    flag = on ? FASYNC : 0;
490
491    /* Did FASYNC state change ? */
492    if ((flag ^ filp->f_flags) & FASYNC) {
493        if (filp->f_op && filp->f_op->fasync)
494            /* fasync() adjusts filp->f_flags */
495            error = filp->f_op->fasync(fd, filp, on);
496        else
497            error = -ENOTTY;
498    }
499    return error < 0 ? error : 0;
500}
501
502static int ioctl_fsfreeze(struct file *filp)
503{
504    struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
505
506    if (!capable(CAP_SYS_ADMIN))
507        return -EPERM;
508
509    /* If filesystem doesn't support freeze feature, return. */
510    if (sb->s_op->freeze_fs == NULL)
511        return -EOPNOTSUPP;
512
513    /* If a blockdevice-backed filesystem isn't specified, return. */
514    if (sb->s_bdev == NULL)
515        return -EINVAL;
516
517    /* Freeze */
518    sb = freeze_bdev(sb->s_bdev);
519    if (IS_ERR(sb))
520        return PTR_ERR(sb);
521    return 0;
522}
523
524static int ioctl_fsthaw(struct file *filp)
525{
526    struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
527
528    if (!capable(CAP_SYS_ADMIN))
529        return -EPERM;
530
531    /* If a blockdevice-backed filesystem isn't specified, return EINVAL. */
532    if (sb->s_bdev == NULL)
533        return -EINVAL;
534
535    /* Thaw */
536    return thaw_bdev(sb->s_bdev, sb);
537}
538
539/*
540 * When you add any new common ioctls to the switches above and below
541 * please update compat_sys_ioctl() too.
542 *
543 * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
544 * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
545 */
546int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
547         unsigned long arg)
548{
549    int error = 0;
550    int __user *argp = (int __user *)arg;
551
552    switch (cmd) {
553    case FIOCLEX:
554        set_close_on_exec(fd, 1);
555        break;
556
557    case FIONCLEX:
558        set_close_on_exec(fd, 0);
559        break;
560
561    case FIONBIO:
562        error = ioctl_fionbio(filp, argp);
563        break;
564
565    case FIOASYNC:
566        error = ioctl_fioasync(fd, filp, argp);
567        break;
568
569    case FIOQSIZE:
570        if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
571            S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
572            S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
573            loff_t res =
574                inode_get_bytes(filp->f_path.dentry->d_inode);
575            error = copy_to_user((loff_t __user *)arg, &res,
576                         sizeof(res)) ? -EFAULT : 0;
577        } else
578            error = -ENOTTY;
579        break;
580
581    case FIFREEZE:
582        error = ioctl_fsfreeze(filp);
583        break;
584
585    case FITHAW:
586        error = ioctl_fsthaw(filp);
587        break;
588
589    case FS_IOC_FIEMAP:
590        return ioctl_fiemap(filp, arg);
591
592    case FIGETBSZ:
593    {
594        struct inode *inode = filp->f_path.dentry->d_inode;
595        int __user *p = (int __user *)arg;
596        return put_user(inode->i_sb->s_blocksize, p);
597    }
598
599    default:
600        if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
601            error = file_ioctl(filp, cmd, arg);
602        else
603            error = vfs_ioctl(filp, cmd, arg);
604        break;
605    }
606    return error;
607}
608
609SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
610{
611    struct file *filp;
612    int error = -EBADF;
613    int fput_needed;
614
615    filp = fget_light(fd, &fput_needed);
616    if (!filp)
617        goto out;
618
619    error = security_file_ioctl(filp, cmd, arg);
620    if (error)
621        goto out_fput;
622
623    error = do_vfs_ioctl(filp, fd, cmd, arg);
624 out_fput:
625    fput_light(filp, fput_needed);
626 out:
627    return error;
628}
629

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