// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
 */

#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/cred.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/msdos_fs.h>
#include <linux/writeback.h>
#include <linux/filelock.h>

#include "exfat_raw.h"
#include "exfat_fs.h"

static int exfat_cont_expand(struct inode *inode, loff_t size)
{
        int ret;
        unsigned int num_clusters, new_num_clusters, last_clu;
        struct exfat_inode_info *ei = EXFAT_I(inode);
        struct super_block *sb = inode->i_sb;
        struct exfat_sb_info *sbi = EXFAT_SB(sb);
        struct exfat_chain clu;

        truncate_pagecache(inode, i_size_read(inode));

        ret = inode_newsize_ok(inode, size);
        if (ret)
                return ret;

        num_clusters = EXFAT_B_TO_CLU(exfat_ondisk_size(inode), sbi);
        new_num_clusters = EXFAT_B_TO_CLU_ROUND_UP(size, sbi);

        if (new_num_clusters == num_clusters)
                goto out;

        if (num_clusters) {
                exfat_chain_set(&clu, ei->start_clu, num_clusters, ei->flags);
                ret = exfat_find_last_cluster(sb, &clu, &last_clu);
                if (ret)
                        return ret;

                clu.dir = last_clu + 1;
        } else {
                last_clu = EXFAT_EOF_CLUSTER;
                clu.dir = EXFAT_EOF_CLUSTER;
        }

        clu.size = 0;
        clu.flags = ei->flags;

        ret = exfat_alloc_cluster(inode, new_num_clusters - num_clusters,
                        &clu, inode_needs_sync(inode));
        if (ret)
                return ret;

        /* Append new clusters to chain */
        if (num_clusters) {
                if (clu.flags != ei->flags)
                        if (exfat_chain_cont_cluster(sb, ei->start_clu, num_clusters))
                                goto free_clu;

                if (clu.flags == ALLOC_FAT_CHAIN)
                        if (exfat_ent_set(sb, last_clu, clu.dir))
                                goto free_clu;
        } else
                ei->start_clu = clu.dir;

        ei->flags = clu.flags;

out:
        inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
        /* Expanded range not zeroed, do not update valid_size */
        i_size_write(inode, size);

        inode->i_blocks = round_up(size, sbi->cluster_size) >> 9;
        mark_inode_dirty(inode);

        if (IS_SYNC(inode))
                return write_inode_now(inode, 1);

        return 0;

free_clu:
        exfat_free_cluster(inode, &clu);
        return -EIO;
}

static bool exfat_allow_set_time(struct mnt_idmap *idmap,
                                 struct exfat_sb_info *sbi, struct inode *inode)
{
        mode_t allow_utime = sbi->options.allow_utime;

        if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
                            current_fsuid())) {
                if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))
                        allow_utime >>= 3;
                if (allow_utime & MAY_WRITE)
                        return true;
        }

        /* use a default check */
        return false;
}

static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
                struct inode *inode, umode_t *mode_ptr)
{
        mode_t i_mode, mask, perm;

        i_mode = inode->i_mode;

        mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
                sbi->options.fs_fmask : sbi->options.fs_dmask;
        perm = *mode_ptr & ~(S_IFMT | mask);

        /* Of the r and x bits, all (subject to umask) must be present.*/
        if ((perm & 0555) != (i_mode & 0555))
                return -EPERM;

        if (exfat_mode_can_hold_ro(inode)) {
                /*
                 * Of the w bits, either all (subject to umask) or none must
                 * be present.
                 */
                if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
                        return -EPERM;
        } else {
                /*
                 * If exfat_mode_can_hold_ro(inode) is false, can't change
                 * w bits.
                 */
                if ((perm & 0222) != (0222 & ~mask))
                        return -EPERM;
        }

        *mode_ptr &= S_IFMT | perm;

        return 0;
}

/* resize the file length */
int __exfat_truncate(struct inode *inode)
{
        unsigned int num_clusters_new, num_clusters_phys;
        unsigned int last_clu = EXFAT_FREE_CLUSTER;
        struct exfat_chain clu;
        struct super_block *sb = inode->i_sb;
        struct exfat_sb_info *sbi = EXFAT_SB(sb);
        struct exfat_inode_info *ei = EXFAT_I(inode);

        /* check if the given file ID is opened */
        if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
                return -EPERM;

        exfat_set_volume_dirty(sb);

        num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
        num_clusters_phys = EXFAT_B_TO_CLU(exfat_ondisk_size(inode), sbi);

        exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);

        if (i_size_read(inode) > 0) {
                /*
                 * Truncate FAT chain num_clusters after the first cluster
                 * num_clusters = min(new, phys);
                 */
                unsigned int num_clusters =
                        min(num_clusters_new, num_clusters_phys);

                /*
                 * Follow FAT chain
                 * (defensive coding - works fine even with corrupted FAT table
                 */
                if (clu.flags == ALLOC_NO_FAT_CHAIN) {
                        clu.dir += num_clusters;
                        clu.size -= num_clusters;
                } else {
                        while (num_clusters > 0) {
                                last_clu = clu.dir;
                                if (exfat_get_next_cluster(sb, &(clu.dir)))
                                        return -EIO;

                                num_clusters--;
                                clu.size--;
                        }
                }
        } else {
                ei->flags = ALLOC_NO_FAT_CHAIN;
                ei->start_clu = EXFAT_EOF_CLUSTER;
        }

        if (i_size_read(inode) < ei->valid_size)
                ei->valid_size = i_size_read(inode);

        if (ei->type == TYPE_FILE)
                ei->attr |= EXFAT_ATTR_ARCHIVE;

        /*
         * update the directory entry
         *
         * If the directory entry is updated by mark_inode_dirty(), the
         * directory entry will be written after a writeback cycle of
         * updating the bitmap/FAT, which may result in clusters being
         * freed but referenced by the directory entry in the event of a
         * sudden power failure.
         * __exfat_write_inode() is called for directory entry, bitmap
         * and FAT to be written in a same writeback.
         */
        if (__exfat_write_inode(inode, inode_needs_sync(inode)))
                return -EIO;

        /* cut off from the FAT chain */
        if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
                        last_clu != EXFAT_EOF_CLUSTER) {
                if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
                        return -EIO;
        }

        /* invalidate cache and free the clusters */
        /* clear exfat cache */
        exfat_cache_inval_inode(inode);

        /* hint information */
        ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
        ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;

        /* hint_stat will be used if this is directory. */
        ei->hint_stat.eidx = 0;
        ei->hint_stat.clu = ei->start_clu;
        ei->hint_femp.eidx = EXFAT_HINT_NONE;

        /* free the clusters */
        if (exfat_free_cluster(inode, &clu))
                return -EIO;

        return 0;
}

void exfat_truncate(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct exfat_sb_info *sbi = EXFAT_SB(sb);
        struct exfat_inode_info *ei = EXFAT_I(inode);
        int err;

        mutex_lock(&sbi->s_lock);
        if (ei->start_clu == 0) {
                /*
                 * Empty start_clu != ~0 (not allocated)
                 */
                exfat_fs_error(sb, "tried to truncate zeroed cluster.");
                goto write_size;
        }

        err = __exfat_truncate(inode);
        if (err)
                goto write_size;

        inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >> 9;
write_size:
        mutex_unlock(&sbi->s_lock);
}

int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
                  struct kstat *stat, unsigned int request_mask,
                  unsigned int query_flags)
{
        struct inode *inode = d_backing_inode(path->dentry);
        struct exfat_inode_info *ei = EXFAT_I(inode);

        generic_fillattr(idmap, request_mask, inode, stat);
        exfat_truncate_atime(&stat->atime);
        stat->result_mask |= STATX_BTIME;
        stat->btime.tv_sec = ei->i_crtime.tv_sec;
        stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
        stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
        return 0;
}

int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                  struct iattr *attr)
{
        struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
        struct inode *inode = dentry->d_inode;
        unsigned int ia_valid;
        int error;

        if (unlikely(exfat_forced_shutdown(inode->i_sb)))
                return -EIO;

        if ((attr->ia_valid & ATTR_SIZE) &&
            attr->ia_size > i_size_read(inode)) {
                error = exfat_cont_expand(inode, attr->ia_size);
                if (error || attr->ia_valid == ATTR_SIZE)
                        return error;
                attr->ia_valid &= ~ATTR_SIZE;
        }

        /* Check for setting the inode time. */
        ia_valid = attr->ia_valid;
        if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
            exfat_allow_set_time(idmap, sbi, inode)) {
                attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
                                ATTR_TIMES_SET);
        }

        error = setattr_prepare(idmap, dentry, attr);
        attr->ia_valid = ia_valid;
        if (error)
                goto out;

        if (((attr->ia_valid & ATTR_UID) &&
              (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
               sbi->options.fs_uid))) ||
            ((attr->ia_valid & ATTR_GID) &&
              (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
               sbi->options.fs_gid))) ||
            ((attr->ia_valid & ATTR_MODE) &&
             (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
                error = -EPERM;
                goto out;
        }

        /*
         * We don't return -EPERM here. Yes, strange, but this is too
         * old behavior.
         */
        if (attr->ia_valid & ATTR_MODE) {
                if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
                        attr->ia_valid &= ~ATTR_MODE;
        }

        if (attr->ia_valid & ATTR_SIZE)
                inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));

        setattr_copy(idmap, inode, attr);
        exfat_truncate_inode_atime(inode);

        if (attr->ia_valid & ATTR_SIZE) {
                error = exfat_block_truncate_page(inode, attr->ia_size);
                if (error)
                        goto out;

                down_write(&EXFAT_I(inode)->truncate_lock);
                truncate_setsize(inode, attr->ia_size);

                /*
                 * __exfat_write_inode() is called from exfat_truncate(), inode
                 * is already written by it, so mark_inode_dirty() is unneeded.
                 */
                exfat_truncate(inode);
                up_write(&EXFAT_I(inode)->truncate_lock);
        } else
                mark_inode_dirty(inode);

out:
        return error;
}

/*
 * modified ioctls from fat/file.c by Welmer Almesberger
 */
static int exfat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
{
        u32 attr;

        inode_lock_shared(inode);
        attr = exfat_make_attr(inode);
        inode_unlock_shared(inode);

        return put_user(attr, user_attr);
}

static int exfat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
{
        struct inode *inode = file_inode(file);
        struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);
        int is_dir = S_ISDIR(inode->i_mode);
        u32 attr, oldattr;
        struct iattr ia;
        int err;

        err = get_user(attr, user_attr);
        if (err)
                goto out;

        err = mnt_want_write_file(file);
        if (err)
                goto out;
        inode_lock(inode);

        oldattr = exfat_make_attr(inode);

        /*
         * Mask attributes so we don't set reserved fields.
         */
        attr &= (EXFAT_ATTR_READONLY | EXFAT_ATTR_HIDDEN | EXFAT_ATTR_SYSTEM |
                 EXFAT_ATTR_ARCHIVE);
        attr |= (is_dir ? EXFAT_ATTR_SUBDIR : 0);

        /* Equivalent to a chmod() */
        ia.ia_valid = ATTR_MODE | ATTR_CTIME;
        ia.ia_ctime = current_time(inode);
        if (is_dir)
                ia.ia_mode = exfat_make_mode(sbi, attr, 0777);
        else
                ia.ia_mode = exfat_make_mode(sbi, attr, 0666 | (inode->i_mode & 0111));

        /* The root directory has no attributes */
        if (inode->i_ino == EXFAT_ROOT_INO && attr != EXFAT_ATTR_SUBDIR) {
                err = -EINVAL;
                goto out_unlock_inode;
        }

        if (((attr | oldattr) & EXFAT_ATTR_SYSTEM) &&
            !capable(CAP_LINUX_IMMUTABLE)) {
                err = -EPERM;
                goto out_unlock_inode;
        }

        /*
         * The security check is questionable...  We single
         * out the RO attribute for checking by the security
         * module, just because it maps to a file mode.
         */
        err = security_inode_setattr(file_mnt_idmap(file),
                                     file->f_path.dentry, &ia);
        if (err)
                goto out_unlock_inode;

        /* This MUST be done before doing anything irreversible... */
        err = exfat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);
        if (err)
                goto out_unlock_inode;

        fsnotify_change(file->f_path.dentry, ia.ia_valid);

        exfat_save_attr(inode, attr);
        mark_inode_dirty(inode);
out_unlock_inode:
        inode_unlock(inode);
        mnt_drop_write_file(file);
out:
        return err;
}

static int exfat_ioctl_fitrim(struct inode *inode, unsigned long arg)
{
        struct fstrim_range range;
        int ret = 0;

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

        if (!bdev_max_discard_sectors(inode->i_sb->s_bdev))
                return -EOPNOTSUPP;

        if (copy_from_user(&range, (struct fstrim_range __user *)arg, sizeof(range)))
                return -EFAULT;

        range.minlen = max_t(unsigned int, range.minlen,
                                bdev_discard_granularity(inode->i_sb->s_bdev));

        ret = exfat_trim_fs(inode, &range);
        if (ret < 0)
                return ret;

        if (copy_to_user((struct fstrim_range __user *)arg, &range, sizeof(range)))
                return -EFAULT;

        return 0;
}

static int exfat_ioctl_shutdown(struct super_block *sb, unsigned long arg)
{
        u32 flags;

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

        if (get_user(flags, (__u32 __user *)arg))
                return -EFAULT;

        return exfat_force_shutdown(sb, flags);
}

static int exfat_ioctl_get_volume_label(struct super_block *sb, unsigned long arg)
{
        int ret;
        char label[FSLABEL_MAX] = {0};
        struct exfat_uni_name uniname;

        ret = exfat_read_volume_label(sb, &uniname);
        if (ret < 0)
                return ret;

        ret = exfat_utf16_to_nls(sb, &uniname, label, uniname.name_len);
        if (ret < 0)
                return ret;

        if (copy_to_user((char __user *)arg, label, ret + 1))
                return -EFAULT;

        return 0;
}

static int exfat_ioctl_set_volume_label(struct super_block *sb,
                                        unsigned long arg)
{
        int ret = 0, lossy, label_len;
        char label[FSLABEL_MAX] = {0};
        struct exfat_uni_name uniname;

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

        if (copy_from_user(label, (char __user *)arg, FSLABEL_MAX))
                return -EFAULT;

        memset(&uniname, 0, sizeof(uniname));
        label_len = strnlen(label, FSLABEL_MAX - 1);
        if (label[0]) {
                ret = exfat_nls_to_utf16(sb, label, label_len,
                                         &uniname, &lossy);
                if (ret < 0)
                        return ret;
                else if (lossy & NLS_NAME_LOSSY)
                        return -EINVAL;
        }

        uniname.name_len = ret;

        return exfat_write_volume_label(sb, &uniname);
}

long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct inode *inode = file_inode(filp);
        u32 __user *user_attr = (u32 __user *)arg;

        switch (cmd) {
        case FAT_IOCTL_GET_ATTRIBUTES:
                return exfat_ioctl_get_attributes(inode, user_attr);
        case FAT_IOCTL_SET_ATTRIBUTES:
                return exfat_ioctl_set_attributes(filp, user_attr);
        case EXFAT_IOC_SHUTDOWN:
                return exfat_ioctl_shutdown(inode->i_sb, arg);
        case FITRIM:
                return exfat_ioctl_fitrim(inode, arg);
        case FS_IOC_GETFSLABEL:
                return exfat_ioctl_get_volume_label(inode->i_sb, arg);
        case FS_IOC_SETFSLABEL:
                return exfat_ioctl_set_volume_label(inode->i_sb, arg);
        default:
                return -ENOTTY;
        }
}

#ifdef CONFIG_COMPAT
long exfat_compat_ioctl(struct file *filp, unsigned int cmd,
                                unsigned long arg)
{
        return exfat_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#endif

int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
        struct inode *inode = filp->f_mapping->host;
        int err;

        if (unlikely(exfat_forced_shutdown(inode->i_sb)))
                return -EIO;

        err = __generic_file_fsync(filp, start, end, datasync);
        if (err)
                return err;

        err = sync_blockdev(inode->i_sb->s_bdev);
        if (err)
                return err;

        return blkdev_issue_flush(inode->i_sb->s_bdev);
}

static int exfat_extend_valid_size(struct inode *inode, loff_t new_valid_size)
{
        int err;
        loff_t pos;
        struct exfat_inode_info *ei = EXFAT_I(inode);
        struct address_space *mapping = inode->i_mapping;
        const struct address_space_operations *ops = mapping->a_ops;

        pos = ei->valid_size;
        while (pos < new_valid_size) {
                u32 len;
                struct folio *folio;
                unsigned long off;

                len = PAGE_SIZE - (pos & (PAGE_SIZE - 1));
                if (pos + len > new_valid_size)
                        len = new_valid_size - pos;

                err = ops->write_begin(NULL, mapping, pos, len, &folio, NULL);
                if (err)
                        goto out;

                off = offset_in_folio(folio, pos);
                folio_zero_new_buffers(folio, off, off + len);

                err = ops->write_end(NULL, mapping, pos, len, len, folio, NULL);
                if (err < 0)
                        goto out;
                pos += len;

                balance_dirty_pages_ratelimited(mapping);
                cond_resched();
        }

        return 0;

out:
        return err;
}

static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        ssize_t ret;
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct exfat_inode_info *ei = EXFAT_I(inode);
        loff_t pos = iocb->ki_pos;
        loff_t valid_size;

        if (unlikely(exfat_forced_shutdown(inode->i_sb)))
                return -EIO;

        inode_lock(inode);

        if (pos > i_size_read(inode))
                truncate_pagecache(inode, i_size_read(inode));

        valid_size = ei->valid_size;

        ret = generic_write_checks(iocb, iter);
        if (ret <= 0)
                goto unlock;

        if (iocb->ki_flags & IOCB_DIRECT) {
                unsigned long align = pos | iov_iter_alignment(iter);

                if (!IS_ALIGNED(align, i_blocksize(inode)) &&
                    !IS_ALIGNED(align, bdev_logical_block_size(inode->i_sb->s_bdev))) {
                        ret = -EINVAL;
                        goto unlock;
                }
        }

        if (pos > valid_size) {
                ret = exfat_extend_valid_size(inode, pos);
                if (ret < 0 && ret != -ENOSPC) {
                        exfat_err(inode->i_sb,
                                "write: fail to zero from %llu to %llu(%zd)",
                                valid_size, pos, ret);
                }
                if (ret < 0)
                        goto unlock;
        }

        ret = __generic_file_write_iter(iocb, iter);
        if (ret < 0)
                goto unlock;

        inode_unlock(inode);

        if (pos > valid_size)
                pos = valid_size;

        if (iocb->ki_pos > pos) {
                ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos);

                if (err < 0)
                        return err;
        }

        return ret;

unlock:
        inode_unlock(inode);

        return ret;
}

static ssize_t exfat_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        struct inode *inode = file_inode(iocb->ki_filp);

        if (unlikely(exfat_forced_shutdown(inode->i_sb)))
                return -EIO;

        return generic_file_read_iter(iocb, iter);
}

static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
{
        int err;
        struct inode *inode = file_inode(vmf->vma->vm_file);
        struct exfat_inode_info *ei = EXFAT_I(inode);
        loff_t new_valid_size;

        if (!inode_trylock(inode))
                return VM_FAULT_RETRY;

        new_valid_size = ((loff_t)vmf->pgoff + 1) << PAGE_SHIFT;
        new_valid_size = min(new_valid_size, i_size_read(inode));

        if (ei->valid_size < new_valid_size) {
                err = exfat_extend_valid_size(inode, new_valid_size);
                if (err < 0) {
                        inode_unlock(inode);
                        return vmf_fs_error(err);
                }
        }

        inode_unlock(inode);

        return filemap_page_mkwrite(vmf);
}

static const struct vm_operations_struct exfat_file_vm_ops = {
        .fault          = filemap_fault,
        .map_pages      = filemap_map_pages,
        .page_mkwrite   = exfat_page_mkwrite,
};

static int exfat_file_mmap_prepare(struct vm_area_desc *desc)
{
        struct file *file = desc->file;

        if (unlikely(exfat_forced_shutdown(file_inode(desc->file)->i_sb)))
                return -EIO;

        file_accessed(file);
        desc->vm_ops = &exfat_file_vm_ops;
        return 0;
}

static ssize_t exfat_splice_read(struct file *in, loff_t *ppos,
                struct pipe_inode_info *pipe, size_t len, unsigned int flags)
{
        if (unlikely(exfat_forced_shutdown(file_inode(in)->i_sb)))
                return -EIO;

        return filemap_splice_read(in, ppos, pipe, len, flags);
}

const struct file_operations exfat_file_operations = {
        .llseek         = generic_file_llseek,
        .read_iter      = exfat_file_read_iter,
        .write_iter     = exfat_file_write_iter,
        .unlocked_ioctl = exfat_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = exfat_compat_ioctl,
#endif
        .mmap_prepare   = exfat_file_mmap_prepare,
        .fsync          = exfat_file_fsync,
        .splice_read    = exfat_splice_read,
        .splice_write   = iter_file_splice_write,
        .setlease       = generic_setlease,
};

const struct inode_operations exfat_file_inode_operations = {
        .setattr     = exfat_setattr,
        .getattr     = exfat_getattr,
};