root/fs/udf/file.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * file.c
 *
 * PURPOSE
 *  File handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *  (C) 1998-1999 Dave Boynton
 *  (C) 1998-2004 Ben Fennema
 *  (C) 1999-2000 Stelias Computing Inc
 *
 * HISTORY
 *
 *  10/02/98 dgb  Attempt to integrate into udf.o
 *  10/07/98      Switched to using generic_readpage, etc., like isofs
 *                And it works!
 *  12/06/98 blf  Added udf_file_read. uses generic_file_read for all cases but
 *                ICBTAG_FLAG_AD_IN_ICB.
 *  04/06/99      64 bit file handling on 32 bit systems taken from ext2 file.c
 *  05/12/99      Preliminary file write support
 */

#include "udfdecl.h"
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/string.h> /* memset */
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/filelock.h>
#include <linux/pagemap.h>
#include <linux/uio.h>

#include "udf_i.h"
#include "udf_sb.h"

static vm_fault_t udf_page_mkwrite(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct inode *inode = file_inode(vma->vm_file);
        struct address_space *mapping = inode->i_mapping;
        struct folio *folio = page_folio(vmf->page);
        loff_t size;
        unsigned int end;
        vm_fault_t ret = VM_FAULT_LOCKED;
        int err;

        sb_start_pagefault(inode->i_sb);
        file_update_time(vma->vm_file);
        filemap_invalidate_lock_shared(mapping);
        folio_lock(folio);
        size = i_size_read(inode);
        if (folio->mapping != inode->i_mapping || folio_pos(folio) >= size) {
                folio_unlock(folio);
                ret = VM_FAULT_NOPAGE;
                goto out_unlock;
        }
        /* Space is already allocated for in-ICB file */
        if (UDF_I(inode)->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB)
                goto out_dirty;
        if (folio->index == size >> PAGE_SHIFT)
                end = size & ~PAGE_MASK;
        else
                end = PAGE_SIZE;
        err = __block_write_begin(folio, 0, end, udf_get_block);
        if (err) {
                folio_unlock(folio);
                ret = vmf_fs_error(err);
                goto out_unlock;
        }

        block_commit_write(folio, 0, end);
out_dirty:
        folio_mark_dirty(folio);
        folio_wait_stable(folio);
out_unlock:
        filemap_invalidate_unlock_shared(mapping);
        sb_end_pagefault(inode->i_sb);
        return ret;
}

static const struct vm_operations_struct udf_file_vm_ops = {
        .fault          = filemap_fault,
        .map_pages      = filemap_map_pages,
        .page_mkwrite   = udf_page_mkwrite,
};

static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        ssize_t retval;
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct udf_inode_info *iinfo = UDF_I(inode);

        inode_lock(inode);

        retval = generic_write_checks(iocb, from);
        if (retval <= 0)
                goto out;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB &&
            inode->i_sb->s_blocksize < (udf_file_entry_alloc_offset(inode) +
                                 iocb->ki_pos + iov_iter_count(from))) {
                filemap_invalidate_lock(inode->i_mapping);
                retval = udf_expand_file_adinicb(inode);
                filemap_invalidate_unlock(inode->i_mapping);
                if (retval)
                        goto out;
        }

        retval = __generic_file_write_iter(iocb, from);
out:
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB && retval > 0) {
                down_write(&iinfo->i_data_sem);
                iinfo->i_lenAlloc = inode->i_size;
                up_write(&iinfo->i_data_sem);
        }
        inode_unlock(inode);

        if (retval > 0) {
                mark_inode_dirty(inode);
                retval = generic_write_sync(iocb, retval);
        }

        return retval;
}

long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct inode *inode = file_inode(filp);
        long old_block, new_block;
        int result;

        if (file_permission(filp, MAY_READ) != 0) {
                udf_debug("no permission to access inode %lu\n", inode->i_ino);
                return -EPERM;
        }

        if (!arg && ((cmd == UDF_GETVOLIDENT) || (cmd == UDF_GETEASIZE) ||
                     (cmd == UDF_RELOCATE_BLOCKS) || (cmd == UDF_GETEABLOCK))) {
                udf_debug("invalid argument to udf_ioctl\n");
                return -EINVAL;
        }

        switch (cmd) {
        case UDF_GETVOLIDENT:
                if (copy_to_user((char __user *)arg,
                                 UDF_SB(inode->i_sb)->s_volume_ident, 32))
                        return -EFAULT;
                return 0;
        case UDF_RELOCATE_BLOCKS:
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;
                if (get_user(old_block, (long __user *)arg))
                        return -EFAULT;
                result = udf_relocate_blocks(inode->i_sb,
                                                old_block, &new_block);
                if (result == 0)
                        result = put_user(new_block, (long __user *)arg);
                return result;
        case UDF_GETEASIZE:
                return put_user(UDF_I(inode)->i_lenEAttr, (int __user *)arg);
        case UDF_GETEABLOCK:
                return copy_to_user((char __user *)arg,
                                    UDF_I(inode)->i_data,
                                    UDF_I(inode)->i_lenEAttr) ? -EFAULT : 0;
        default:
                return -ENOIOCTLCMD;
        }

        return 0;
}

static int udf_release_file(struct inode *inode, struct file *filp)
{
        if (filp->f_mode & FMODE_WRITE &&
            atomic_read(&inode->i_writecount) == 1) {
                /*
                 * Grab i_mutex to avoid races with writes changing i_size
                 * while we are running.
                 */
                inode_lock(inode);
                down_write(&UDF_I(inode)->i_data_sem);
                udf_discard_prealloc(inode);
                udf_truncate_tail_extent(inode);
                up_write(&UDF_I(inode)->i_data_sem);
                inode_unlock(inode);
        }
        return 0;
}

static int udf_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        file_accessed(file);
        vma->vm_ops = &udf_file_vm_ops;

        return 0;
}

const struct file_operations udf_file_operations = {
        .read_iter              = generic_file_read_iter,
        .unlocked_ioctl         = udf_ioctl,
        .open                   = generic_file_open,
        .mmap                   = udf_file_mmap,
        .write_iter             = udf_file_write_iter,
        .release                = udf_release_file,
        .fsync                  = generic_file_fsync,
        .splice_read            = filemap_splice_read,
        .splice_write           = iter_file_splice_write,
        .llseek                 = generic_file_llseek,
        .setlease               = generic_setlease,
};

static int udf_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                       struct iattr *attr)
{
        struct inode *inode = d_inode(dentry);
        struct super_block *sb = inode->i_sb;
        int error;

        error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
        if (error)
                return error;

        if ((attr->ia_valid & ATTR_UID) &&
            UDF_QUERY_FLAG(sb, UDF_FLAG_UID_SET) &&
            !uid_eq(attr->ia_uid, UDF_SB(sb)->s_uid))
                return -EPERM;
        if ((attr->ia_valid & ATTR_GID) &&
            UDF_QUERY_FLAG(sb, UDF_FLAG_GID_SET) &&
            !gid_eq(attr->ia_gid, UDF_SB(sb)->s_gid))
                return -EPERM;

        if ((attr->ia_valid & ATTR_SIZE) &&
            attr->ia_size != i_size_read(inode)) {
                filemap_invalidate_lock(inode->i_mapping);
                error = udf_setsize(inode, attr->ia_size);
                filemap_invalidate_unlock(inode->i_mapping);
                if (error)
                        return error;
        }

        if (attr->ia_valid & ATTR_MODE)
                udf_update_extra_perms(inode, attr->ia_mode);

        setattr_copy(&nop_mnt_idmap, inode, attr);
        mark_inode_dirty(inode);
        return 0;
}

const struct inode_operations udf_file_inode_operations = {
        .setattr                = udf_setattr,
};