do_signal() does __put_user() which can fault, resulting in a

[linux-2.6/linux-mips.git] / fs / ioctl.c

/*
 *  linux/fs/ioctl.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/syscalls.h>
#include <linux/mm.h>
#include <linux/capability.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/falloc.h>

#include <asm/ioctls.h>

/* So that the fiemap access checks can't overflow on 32 bit machines. */
#define FIEMAP_MAX_EXTENTS      (UINT_MAX / sizeof(struct fiemap_extent))

/**
 * vfs_ioctl - call filesystem specific ioctl methods
 * @filp:       open file to invoke ioctl method on
 * @cmd:        ioctl command to execute
 * @arg:        command-specific argument for ioctl
 *
 * Invokes filesystem specific ->unlocked_ioctl, if one exists; otherwise
 * returns -ENOTTY.
 *
 * Returns 0 on success, -errno on error.
 */
static long vfs_ioctl(struct file *filp, unsigned int cmd,
                      unsigned long arg)
{
        int error = -ENOTTY;

        if (!filp->f_op || !filp->f_op->unlocked_ioctl)
                goto out;

        error = filp->f_op->unlocked_ioctl(filp, cmd, arg);
        if (error == -ENOIOCTLCMD)
                error = -EINVAL;
 out:
        return error;
}

static int ioctl_fibmap(struct file *filp, int __user *p)
{
        struct address_space *mapping = filp->f_mapping;
        int res, block;

        /* do we support this mess? */
        if (!mapping->a_ops->bmap)
                return -EINVAL;
        if (!capable(CAP_SYS_RAWIO))
                return -EPERM;
        res = get_user(block, p);
        if (res)
                return res;
        res = mapping->a_ops->bmap(mapping, block);
        return put_user(res, p);
}

/**
 * fiemap_fill_next_extent - Fiemap helper function
 * @fieinfo:    Fiemap context passed into ->fiemap
 * @logical:    Extent logical start offset, in bytes
 * @phys:       Extent physical start offset, in bytes
 * @len:        Extent length, in bytes
 * @flags:      FIEMAP_EXTENT flags that describe this extent
 *
 * Called from file system ->fiemap callback. Will populate extent
 * info as passed in via arguments and copy to user memory. On
 * success, extent count on fieinfo is incremented.
 *
 * Returns 0 on success, -errno on error, 1 if this was the last
 * extent that will fit in user array.
 */
#define SET_UNKNOWN_FLAGS       (FIEMAP_EXTENT_DELALLOC)
#define SET_NO_UNMOUNTED_IO_FLAGS       (FIEMAP_EXTENT_DATA_ENCRYPTED)
#define SET_NOT_ALIGNED_FLAGS   (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
                            u64 phys, u64 len, u32 flags)
{
        struct fiemap_extent extent;
        struct fiemap_extent __user *dest = fieinfo->fi_extents_start;

        /* only count the extents */
        if (fieinfo->fi_extents_max == 0) {
                fieinfo->fi_extents_mapped++;
                return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
        }

        if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
                return 1;

        if (flags & SET_UNKNOWN_FLAGS)
                flags |= FIEMAP_EXTENT_UNKNOWN;
        if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
                flags |= FIEMAP_EXTENT_ENCODED;
        if (flags & SET_NOT_ALIGNED_FLAGS)
                flags |= FIEMAP_EXTENT_NOT_ALIGNED;

        memset(&extent, 0, sizeof(extent));
        extent.fe_logical = logical;
        extent.fe_physical = phys;
        extent.fe_length = len;
        extent.fe_flags = flags;

        dest += fieinfo->fi_extents_mapped;
        if (copy_to_user(dest, &extent, sizeof(extent)))
                return -EFAULT;

        fieinfo->fi_extents_mapped++;
        if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
                return 1;
        return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
}
EXPORT_SYMBOL(fiemap_fill_next_extent);

/**
 * fiemap_check_flags - check validity of requested flags for fiemap
 * @fieinfo:    Fiemap context passed into ->fiemap
 * @fs_flags:   Set of fiemap flags that the file system understands
 *
 * Called from file system ->fiemap callback. This will compute the
 * intersection of valid fiemap flags and those that the fs supports. That
 * value is then compared against the user supplied flags. In case of bad user
 * flags, the invalid values will be written into the fieinfo structure, and
 * -EBADR is returned, which tells ioctl_fiemap() to return those values to
 * userspace. For this reason, a return code of -EBADR should be preserved.
 *
 * Returns 0 on success, -EBADR on bad flags.
 */
int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
{
        u32 incompat_flags;

        incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
        if (incompat_flags) {
                fieinfo->fi_flags = incompat_flags;
                return -EBADR;
        }
        return 0;
}
EXPORT_SYMBOL(fiemap_check_flags);

static int fiemap_check_ranges(struct super_block *sb,
                               u64 start, u64 len, u64 *new_len)
{
        u64 maxbytes = (u64) sb->s_maxbytes;

        *new_len = len;

        if (len == 0)
                return -EINVAL;

        if (start > maxbytes)
                return -EFBIG;

        /*
         * Shrink request scope to what the fs can actually handle.
         */
        if (len > maxbytes || (maxbytes - len) < start)
                *new_len = maxbytes - start;

        return 0;
}

static int ioctl_fiemap(struct file *filp, unsigned long arg)
{
        struct fiemap fiemap;
        struct fiemap __user *ufiemap = (struct fiemap __user *) arg;
        struct fiemap_extent_info fieinfo = { 0, };
        struct inode *inode = filp->f_path.dentry->d_inode;
        struct super_block *sb = inode->i_sb;
        u64 len;
        int error;

        if (!inode->i_op->fiemap)
                return -EOPNOTSUPP;

        if (copy_from_user(&fiemap, ufiemap, sizeof(fiemap)))
                return -EFAULT;

        if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
                return -EINVAL;

        error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
                                    &len);
        if (error)
                return error;

        fieinfo.fi_flags = fiemap.fm_flags;
        fieinfo.fi_extents_max = fiemap.fm_extent_count;
        fieinfo.fi_extents_start = ufiemap->fm_extents;

        if (fiemap.fm_extent_count != 0 &&
            !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
                       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
                return -EFAULT;

        if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
                filemap_write_and_wait(inode->i_mapping);

        error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
        fiemap.fm_flags = fieinfo.fi_flags;
        fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
        if (copy_to_user(ufiemap, &fiemap, sizeof(fiemap)))
                error = -EFAULT;

        return error;
}

#ifdef CONFIG_BLOCK

static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
{
        return (offset >> inode->i_blkbits);
}

static inline loff_t blk_to_logical(struct inode *inode, sector_t blk)
{
        return (blk << inode->i_blkbits);
}

/**
 * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
 * @inode: the inode to map
 * @fieinfo: the fiemap info struct that will be passed back to userspace
 * @start: where to start mapping in the inode
 * @len: how much space to map
 * @get_block: the fs's get_block function
 *
 * This does FIEMAP for block based inodes.  Basically it will just loop
 * through get_block until we hit the number of extents we want to map, or we
 * go past the end of the file and hit a hole.
 *
 * If it is possible to have data blocks beyond a hole past @inode->i_size, then
 * please do not use this function, it will stop at the first unmapped block
 * beyond i_size.
 *
 * If you use this function directly, you need to do your own locking. Use
 * generic_block_fiemap if you want the locking done for you.
 */

int __generic_block_fiemap(struct inode *inode,
                           struct fiemap_extent_info *fieinfo, loff_t start,
                           loff_t len, get_block_t *get_block)
{
        struct buffer_head map_bh;
        sector_t start_blk, last_blk;
        loff_t isize = i_size_read(inode);
        u64 logical = 0, phys = 0, size = 0;
        u32 flags = FIEMAP_EXTENT_MERGED;
        bool past_eof = false, whole_file = false;
        int ret = 0;

        ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
        if (ret)
                return ret;

        /*
         * Either the i_mutex or other appropriate locking needs to be held
         * since we expect isize to not change at all through the duration of
         * this call.
         */
        if (len >= isize) {
                whole_file = true;
                len = isize;
        }

        /*
         * Some filesystems can't deal with being asked to map less than
         * blocksize, so make sure our len is at least block length.
         */
        if (logical_to_blk(inode, len) == 0)
                len = blk_to_logical(inode, 1);

        start_blk = logical_to_blk(inode, start);
        last_blk = logical_to_blk(inode, start + len - 1);

        do {
                /*
                 * we set b_size to the total size we want so it will map as
                 * many contiguous blocks as possible at once
                 */
                memset(&map_bh, 0, sizeof(struct buffer_head));
                map_bh.b_size = len;

                ret = get_block(inode, start_blk, &map_bh, 0);
                if (ret)
                        break;

                /* HOLE */
                if (!buffer_mapped(&map_bh)) {
                        start_blk++;

                        /*
                         * We want to handle the case where there is an
                         * allocated block at the front of the file, and then
                         * nothing but holes up to the end of the file properly,
                         * to make sure that extent at the front gets properly
                         * marked with FIEMAP_EXTENT_LAST
                         */
                        if (!past_eof &&
                            blk_to_logical(inode, start_blk) >= isize)
                                past_eof = 1;

                        /*
                         * First hole after going past the EOF, this is our
                         * last extent
                         */
                        if (past_eof && size) {
                                flags = FIEMAP_EXTENT_MERGED|FIEMAP_EXTENT_LAST;
                                ret = fiemap_fill_next_extent(fieinfo, logical,
                                                              phys, size,
                                                              flags);
                        } else if (size) {
                                ret = fiemap_fill_next_extent(fieinfo, logical,
                                                              phys, size, flags);
                                size = 0;
                        }

                        /* if we have holes up to/past EOF then we're done */
                        if (start_blk > last_blk || past_eof || ret)
                                break;
                } else {
                        /*
                         * We have gone over the length of what we wanted to
                         * map, and it wasn't the entire file, so add the extent
                         * we got last time and exit.
                         *
                         * This is for the case where say we want to map all the
                         * way up to the second to the last block in a file, but
                         * the last block is a hole, making the second to last
                         * block FIEMAP_EXTENT_LAST.  In this case we want to
                         * see if there is a hole after the second to last block
                         * so we can mark it properly.  If we found data after
                         * we exceeded the length we were requesting, then we
                         * are good to go, just add the extent to the fieinfo
                         * and break
                         */
                        if (start_blk > last_blk && !whole_file) {
                                ret = fiemap_fill_next_extent(fieinfo, logical,
                                                              phys, size,
                                                              flags);
                                break;
                        }

                        /*
                         * if size != 0 then we know we already have an extent
                         * to add, so add it.
                         */
                        if (size) {
                                ret = fiemap_fill_next_extent(fieinfo, logical,
                                                              phys, size,
                                                              flags);
                                if (ret)
                                        break;
                        }

                        logical = blk_to_logical(inode, start_blk);
                        phys = blk_to_logical(inode, map_bh.b_blocknr);
                        size = map_bh.b_size;
                        flags = FIEMAP_EXTENT_MERGED;

                        start_blk += logical_to_blk(inode, size);

                        /*
                         * If we are past the EOF, then we need to make sure as
                         * soon as we find a hole that the last extent we found
                         * is marked with FIEMAP_EXTENT_LAST
                         */
                        if (!past_eof && logical + size >= isize)
                                past_eof = true;
                }
                cond_resched();
        } while (1);

        /* If ret is 1 then we just hit the end of the extent array */
        if (ret == 1)
                ret = 0;

        return ret;
}
EXPORT_SYMBOL(__generic_block_fiemap);

/**
 * generic_block_fiemap - FIEMAP for block based inodes
 * @inode: The inode to map
 * @fieinfo: The mapping information
 * @start: The initial block to map
 * @len: The length of the extect to attempt to map
 * @get_block: The block mapping function for the fs
 *
 * Calls __generic_block_fiemap to map the inode, after taking
 * the inode's mutex lock.
 */

int generic_block_fiemap(struct inode *inode,
                         struct fiemap_extent_info *fieinfo, u64 start,
                         u64 len, get_block_t *get_block)
{
        int ret;
        mutex_lock(&inode->i_mutex);
        ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
        mutex_unlock(&inode->i_mutex);
        return ret;
}
EXPORT_SYMBOL(generic_block_fiemap);

#endif  /*  CONFIG_BLOCK  */

/*
 * This provides compatibility with legacy XFS pre-allocation ioctls
 * which predate the fallocate syscall.
 *
 * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
 * are used here, rest are ignored.
 */
int ioctl_preallocate(struct file *filp, void __user *argp)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        struct space_resv sr;

        if (copy_from_user(&sr, argp, sizeof(sr)))
                return -EFAULT;

        switch (sr.l_whence) {
        case SEEK_SET:
                break;
        case SEEK_CUR:
                sr.l_start += filp->f_pos;
                break;
        case SEEK_END:
                sr.l_start += i_size_read(inode);
                break;
        default:
                return -EINVAL;
        }

        return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
}

static int file_ioctl(struct file *filp, unsigned int cmd,
                unsigned long arg)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        int __user *p = (int __user *)arg;

        switch (cmd) {
        case FIBMAP:
                return ioctl_fibmap(filp, p);
        case FIONREAD:
                return put_user(i_size_read(inode) - filp->f_pos, p);
        case FS_IOC_RESVSP:
        case FS_IOC_RESVSP64:
                return ioctl_preallocate(filp, p);
        }

        return vfs_ioctl(filp, cmd, arg);
}

static int ioctl_fionbio(struct file *filp, int __user *argp)
{
        unsigned int flag;
        int on, error;

        error = get_user(on, argp);
        if (error)
                return error;
        flag = O_NONBLOCK;
#ifdef __sparc__
        /* SunOS compatibility item. */
        if (O_NONBLOCK != O_NDELAY)
                flag |= O_NDELAY;
#endif
        spin_lock(&filp->f_lock);
        if (on)
                filp->f_flags |= flag;
        else
                filp->f_flags &= ~flag;
        spin_unlock(&filp->f_lock);
        return error;
}

static int ioctl_fioasync(unsigned int fd, struct file *filp,
                          int __user *argp)
{
        unsigned int flag;
        int on, error;

        error = get_user(on, argp);
        if (error)
                return error;
        flag = on ? FASYNC : 0;

        /* Did FASYNC state change ? */
        if ((flag ^ filp->f_flags) & FASYNC) {
                if (filp->f_op && filp->f_op->fasync)
                        /* fasync() adjusts filp->f_flags */
                        error = filp->f_op->fasync(fd, filp, on);
                else
                        error = -ENOTTY;
        }
        return error < 0 ? error : 0;
}

static int ioctl_fsfreeze(struct file *filp)
{
        struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        /* If filesystem doesn't support freeze feature, return. */
        if (sb->s_op->freeze_fs == NULL)
                return -EOPNOTSUPP;

        /* Freeze */
        return freeze_super(sb);
}

static int ioctl_fsthaw(struct file *filp)
{
        struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        /* Thaw */
        return thaw_super(sb);
}

/*
 * When you add any new common ioctls to the switches above and below
 * please update compat_sys_ioctl() too.
 *
 * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
 * It's just a simple helper for sys_ioctl and compat_sys_ioctl.
 */
int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
             unsigned long arg)
{
        int error = 0;
        int __user *argp = (int __user *)arg;
        struct inode *inode = filp->f_path.dentry->d_inode;

        switch (cmd) {
        case FIOCLEX:
                set_close_on_exec(fd, 1);
                break;

        case FIONCLEX:
                set_close_on_exec(fd, 0);
                break;

        case FIONBIO:
                error = ioctl_fionbio(filp, argp);
                break;

        case FIOASYNC:
                error = ioctl_fioasync(fd, filp, argp);
                break;

        case FIOQSIZE:
                if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode) ||
                    S_ISLNK(inode->i_mode)) {
                        loff_t res = inode_get_bytes(inode);
                        error = copy_to_user(argp, &res, sizeof(res)) ?
                                        -EFAULT : 0;
                } else
                        error = -ENOTTY;
                break;

        case FIFREEZE:
                error = ioctl_fsfreeze(filp);
                break;

        case FITHAW:
                error = ioctl_fsthaw(filp);
                break;

        case FS_IOC_FIEMAP:
                return ioctl_fiemap(filp, arg);

        case FIGETBSZ:
                return put_user(inode->i_sb->s_blocksize, argp);

        default:
                if (S_ISREG(inode->i_mode))
                        error = file_ioctl(filp, cmd, arg);
                else
                        error = vfs_ioctl(filp, cmd, arg);
                break;
        }
        return error;
}

SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
{
        struct file *filp;
        int error = -EBADF;
        int fput_needed;

        filp = fget_light(fd, &fput_needed);
        if (!filp)
                goto out;

        error = security_file_ioctl(filp, cmd, arg);
        if (error)
                goto out_fput;

        error = do_vfs_ioctl(filp, fd, cmd, arg);
 out_fput:
        fput_light(filp, fput_needed);
 out:
        return error;
}