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    u64 maxbytes = (u64) sb->s_maxbytes;
166
167    *new_len = len;
168
169    if (len == 0)
170        return -EINVAL;
171
172    if (start > maxbytes)
173        return -EFBIG;
174
175    /*
176     * Shrink request scope to what the fs can actually handle.
177     */
178    if (len > maxbytes || (maxbytes - len) < start)
179        *new_len = maxbytes - start;
180
181    return 0;
182}
183
184static int ioctl_fiemap(struct file *filp, unsigned long arg)
185{
186    struct fiemap fiemap;
187    struct fiemap_extent_info fieinfo = { 0, };
188    struct inode *inode = filp->f_path.dentry->d_inode;
189    struct super_block *sb = inode->i_sb;
190    u64 len;
191    int error;
192
193    if (!inode->i_op->fiemap)
194        return -EOPNOTSUPP;
195
196    if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
197               sizeof(struct fiemap)))
198        return -EFAULT;
199
200    if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
201        return -EINVAL;
202
203    error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
204                    &len);
205    if (error)
206        return error;
207
208    fieinfo.fi_flags = fiemap.fm_flags;
209    fieinfo.fi_extents_max = fiemap.fm_extent_count;
210    fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
211
212    if (fiemap.fm_extent_count != 0 &&
213        !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
214               fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
215        return -EFAULT;
216
217    if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
218        filemap_write_and_wait(inode->i_mapping);
219
220    error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
221    fiemap.fm_flags = fieinfo.fi_flags;
222    fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
223    if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
224        error = -EFAULT;
225
226    return error;
227}
228
229#ifdef CONFIG_BLOCK
230
231#define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
232#define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
233
234/**
235 * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
236 * @inode - the inode to map
237 * @arg - the pointer to userspace where we copy everything to
238 * @get_block - the fs's get_block function
239 *
240 * This does FIEMAP for block based inodes. Basically it will just loop
241 * through get_block until we hit the number of extents we want to map, or we
242 * go past the end of the file and hit a hole.
243 *
244 * If it is possible to have data blocks beyond a hole past @inode->i_size, then
245 * please do not use this function, it will stop at the first unmapped block
246 * beyond i_size.
247 *
248 * If you use this function directly, you need to do your own locking. Use
249 * generic_block_fiemap if you want the locking done for you.
250 */
251
252int __generic_block_fiemap(struct inode *inode,
253               struct fiemap_extent_info *fieinfo, u64 start,
254               u64 len, get_block_t *get_block)
255{
256    struct buffer_head tmp;
257    unsigned long long start_blk;
258    long long length = 0, map_len = 0;
259    u64 logical = 0, phys = 0, size = 0;
260    u32 flags = FIEMAP_EXTENT_MERGED;
261    int ret = 0, past_eof = 0, whole_file = 0;
262
263    if ((ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC)))
264        return ret;
265
266    start_blk = logical_to_blk(inode, start);
267
268    length = (long long)min_t(u64, len, i_size_read(inode));
269    if (length < len)
270        whole_file = 1;
271
272    map_len = length;
273
274    do {
275        /*
276         * we set b_size to the total size we want so it will map as
277         * many contiguous blocks as possible at once
278         */
279        memset(&tmp, 0, sizeof(struct buffer_head));
280        tmp.b_size = map_len;
281
282        ret = get_block(inode, start_blk, &tmp, 0);
283        if (ret)
284            break;
285
286        /* HOLE */
287        if (!buffer_mapped(&tmp)) {
288            length -= blk_to_logical(inode, 1);
289            start_blk++;
290
291            /*
292             * we want to handle the case where there is an
293             * allocated block at the front of the file, and then
294             * nothing but holes up to the end of the file properly,
295             * to make sure that extent at the front gets properly
296             * marked with FIEMAP_EXTENT_LAST
297             */
298            if (!past_eof &&
299                blk_to_logical(inode, start_blk) >=
300                blk_to_logical(inode, 0)+i_size_read(inode))
301                past_eof = 1;
302
303            /*
304             * first hole after going past the EOF, this is our
305             * last extent
306             */
307            if (past_eof && size) {
308                flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
309                ret = fiemap_fill_next_extent(fieinfo, logical,
310                                  phys, size,
311                                  flags);
312                break;
313            }
314
315            /* if we have holes up to/past EOF then we're done */
316            if (length <= 0 || past_eof)
317                break;
318        } else {
319            /*
320             * we have gone over the length of what we wanted to
321             * map, and it wasn't the entire file, so add the extent
322             * we got last time and exit.
323             *
324             * This is for the case where say we want to map all the
325             * way up to the second to the last block in a file, but
326             * the last block is a hole, making the second to last
327             * block FIEMAP_EXTENT_LAST. In this case we want to
328             * see if there is a hole after the second to last block
329             * so we can mark it properly. If we found data after
330             * we exceeded the length we were requesting, then we
331             * are good to go, just add the extent to the fieinfo
332             * and break
333             */
334            if (length <= 0 && !whole_file) {
335                ret = fiemap_fill_next_extent(fieinfo, logical,
336                                  phys, size,
337                                  flags);
338                break;
339            }
340
341            /*
342             * if size != 0 then we know we already have an extent
343             * to add, so add it.
344             */
345            if (size) {
346                ret = fiemap_fill_next_extent(fieinfo, logical,
347                                  phys, size,
348                                  flags);
349                if (ret)
350                    break;
351            }
352
353            logical = blk_to_logical(inode, start_blk);
354            phys = blk_to_logical(inode, tmp.b_blocknr);
355            size = tmp.b_size;
356            flags = FIEMAP_EXTENT_MERGED;
357
358            length -= tmp.b_size;
359            start_blk += logical_to_blk(inode, size);
360
361            /*
362             * If we are past the EOF, then we need to make sure as
363             * soon as we find a hole that the last extent we found
364             * is marked with FIEMAP_EXTENT_LAST
365             */
366            if (!past_eof &&
367                logical+size >=
368                blk_to_logical(inode, 0)+i_size_read(inode))
369                past_eof = 1;
370        }
371        cond_resched();
372    } while (1);
373
374    /* if ret is 1 then we just hit the end of the extent array */
375    if (ret == 1)
376        ret = 0;
377
378    return ret;
379}
380EXPORT_SYMBOL(__generic_block_fiemap);
381
382/**
383 * generic_block_fiemap - FIEMAP for block based inodes
384 * @inode: The inode to map
385 * @fieinfo: The mapping information
386 * @start: The initial block to map
387 * @len: The length of the extect to attempt to map
388 * @get_block: The block mapping function for the fs
389 *
390 * Calls __generic_block_fiemap to map the inode, after taking
391 * the inode's mutex lock.
392 */
393
394int generic_block_fiemap(struct inode *inode,
395             struct fiemap_extent_info *fieinfo, u64 start,
396             u64 len, get_block_t *get_block)
397{
398    int ret;
399    mutex_lock(&inode->i_mutex);
400    ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
401    mutex_unlock(&inode->i_mutex);
402    return ret;
403}
404EXPORT_SYMBOL(generic_block_fiemap);
405
406#endif /* CONFIG_BLOCK */
407
408/*
409 * This provides compatibility with legacy XFS pre-allocation ioctls
410 * which predate the fallocate syscall.
411 *
412 * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
413 * are used here, rest are ignored.
414 */
415int ioctl_preallocate(struct file *filp, void __user *argp)
416{
417    struct inode *inode = filp->f_path.dentry->d_inode;
418    struct space_resv sr;
419
420    if (copy_from_user(&sr, argp, sizeof(sr)))
421        return -EFAULT;
422
423    switch (sr.l_whence) {
424    case SEEK_SET:
425        break;
426    case SEEK_CUR:
427        sr.l_start += filp->f_pos;
428        break;
429    case SEEK_END:
430        sr.l_start += i_size_read(inode);
431        break;
432    default:
433        return -EINVAL;
434    }
435
436    return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
437}
438
439static int file_ioctl(struct file *filp, unsigned int cmd,
440        unsigned long arg)
441{
442    struct inode *inode = filp->f_path.dentry->d_inode;
443    int __user *p = (int __user *)arg;
444
445    switch (cmd) {
446    case FIBMAP:
447        return ioctl_fibmap(filp, p);
448    case FIONREAD:
449        return put_user(i_size_read(inode) - filp->f_pos, p);
450    case FS_IOC_RESVSP:
451    case FS_IOC_RESVSP64:
452        return ioctl_preallocate(filp, p);
453    }
454
455    return vfs_ioctl(filp, cmd, arg);
456}
457
458static int ioctl_fionbio(struct file *filp, int __user *argp)
459{
460    unsigned int flag;
461    int on, error;
462
463    error = get_user(on, argp);
464    if (error)
465        return error;
466    flag = O_NONBLOCK;
467#ifdef __sparc__
468    /* SunOS compatibility item. */
469    if (O_NONBLOCK != O_NDELAY)
470        flag |= O_NDELAY;
471#endif
472    spin_lock(&filp->f_lock);
473    if (on)
474        filp->f_flags |= flag;
475    else
476        filp->f_flags &= ~flag;
477    spin_unlock(&filp->f_lock);
478    return error;
479}
480
481static int ioctl_fioasync(unsigned int fd, struct file *filp,
482              int __user *argp)
483{
484    unsigned int flag;
485    int on, error;
486
487    error = get_user(on, argp);
488    if (error)
489        return error;
490    flag = on ? FASYNC : 0;
491
492    /* Did FASYNC state change ? */
493    if ((flag ^ filp->f_flags) & FASYNC) {
494        if (filp->f_op && filp->f_op->fasync)
495            /* fasync() adjusts filp->f_flags */
496            error = filp->f_op->fasync(fd, filp, on);
497        else
498            error = -ENOTTY;
499    }
500    return error < 0 ? error : 0;
501}
502
503static int ioctl_fsfreeze(struct file *filp)
504{
505    struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
506
507    if (!capable(CAP_SYS_ADMIN))
508        return -EPERM;
509
510    /* If filesystem doesn't support freeze feature, return. */
511    if (sb->s_op->freeze_fs == NULL)
512        return -EOPNOTSUPP;
513
514    /* If a blockdevice-backed filesystem isn't specified, return. */
515    if (sb->s_bdev == NULL)
516        return -EINVAL;
517
518    /* Freeze */
519    sb = freeze_bdev(sb->s_bdev);
520    if (IS_ERR(sb))
521        return PTR_ERR(sb);
522    return 0;
523}
524
525static int ioctl_fsthaw(struct file *filp)
526{
527    struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;
528
529    if (!capable(CAP_SYS_ADMIN))
530        return -EPERM;
531
532    /* If a blockdevice-backed filesystem isn't specified, return EINVAL. */
533    if (sb->s_bdev == NULL)
534        return -EINVAL;
535
536    /* Thaw */
537    return thaw_bdev(sb->s_bdev, sb);
538}
539
540/*
541 * When you add any new common ioctls to the switches above and below
542 * please update compat_sys_ioctl() too.
543 *
544 * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
545 * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
546 */
547int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
548         unsigned long arg)
549{
550    int error = 0;
551    int __user *argp = (int __user *)arg;
552
553    switch (cmd) {
554    case FIOCLEX:
555        set_close_on_exec(fd, 1);
556        break;
557
558    case FIONCLEX:
559        set_close_on_exec(fd, 0);
560        break;
561
562    case FIONBIO:
563        error = ioctl_fionbio(filp, argp);
564        break;
565
566    case FIOASYNC:
567        error = ioctl_fioasync(fd, filp, argp);
568        break;
569
570    case FIOQSIZE:
571        if (S_ISDIR(filp->f_path.dentry->d_inode->i_mode) ||
572            S_ISREG(filp->f_path.dentry->d_inode->i_mode) ||
573            S_ISLNK(filp->f_path.dentry->d_inode->i_mode)) {
574            loff_t res =
575                inode_get_bytes(filp->f_path.dentry->d_inode);
576            error = copy_to_user((loff_t __user *)arg, &res,
577                         sizeof(res)) ? -EFAULT : 0;
578        } else
579            error = -ENOTTY;
580        break;
581
582    case FIFREEZE:
583        error = ioctl_fsfreeze(filp);
584        break;
585
586    case FITHAW:
587        error = ioctl_fsthaw(filp);
588        break;
589
590    case FS_IOC_FIEMAP:
591        return ioctl_fiemap(filp, arg);
592
593    case FIGETBSZ:
594    {
595        struct inode *inode = filp->f_path.dentry->d_inode;
596        int __user *p = (int __user *)arg;
597        return put_user(inode->i_sb->s_blocksize, p);
598    }
599
600    default:
601        if (S_ISREG(filp->f_path.dentry->d_inode->i_mode))
602            error = file_ioctl(filp, cmd, arg);
603        else
604            error = vfs_ioctl(filp, cmd, arg);
605        break;
606    }
607    return error;
608}
609
610SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
611{
612    struct file *filp;
613    int error = -EBADF;
614    int fput_needed;
615
616    filp = fget_light(fd, &fput_needed);
617    if (!filp)
618        goto out;
619
620    error = security_file_ioctl(filp, cmd, arg);
621    if (error)
622        goto out_fput;
623
624    error = do_vfs_ioctl(filp, fd, cmd, arg);
625 out_fput:
626    fput_light(filp, fput_needed);
627 out:
628    return error;
629}
630

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