// SPDX-License-Identifier: GPL-2.0
#include "ubifs.h"

static int ubifs_crypt_get_context(struct inode *inode, void *ctx, size_t len)
{
        return ubifs_xattr_get(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,
                               ctx, len);
}

static int ubifs_crypt_set_context(struct inode *inode, const void *ctx,
                                   size_t len, void *fs_data)
{
        /*
         * Creating an encryption context is done unlocked since we
         * operate on a new inode which is not visible to other users
         * at this point. So, no need to check whether inode is locked.
         */
        return ubifs_xattr_set(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,
                               ctx, len, 0, false);
}

static bool ubifs_crypt_empty_dir(struct inode *inode)
{
        return ubifs_check_dir_empty(inode) == 0;
}

/**
 * ubifs_encrypt - Encrypt data.
 * @inode: inode which refers to the data node
 * @dn: data node to encrypt
 * @in_len: length of data to be compressed
 * @out_len: allocated memory size for the data area of @dn
 * @block: logical block number of the block
 *
 * This function encrypt a possibly-compressed data in the data node.
 * The encrypted data length will store in @out_len.
 */
int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
                  unsigned int in_len, unsigned int *out_len, int block)
{
        struct ubifs_info *c = inode->i_sb->s_fs_info;
        void *p = &dn->data;
        unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
        int err;

        ubifs_assert(c, pad_len <= *out_len);
        dn->compr_size = cpu_to_le16(in_len);

        /* pad to full block cipher length */
        if (pad_len != in_len)
                memset(p + in_len, 0, pad_len - in_len);

        err = fscrypt_encrypt_block_inplace(inode, virt_to_page(p), pad_len,
                                            offset_in_page(p), block);
        if (err) {
                ubifs_err(c, "fscrypt_encrypt_block_inplace() failed: %d", err);
                return err;
        }
        *out_len = pad_len;

        return 0;
}

int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
                  unsigned int *out_len, int block)
{
        struct ubifs_info *c = inode->i_sb->s_fs_info;
        int err;
        unsigned int clen = le16_to_cpu(dn->compr_size);
        unsigned int dlen = *out_len;

        if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen) {
                ubifs_err(c, "bad compr_size: %i", clen);
                return -EINVAL;
        }

        ubifs_assert(c, dlen <= UBIFS_BLOCK_SIZE);
        err = fscrypt_decrypt_block_inplace(inode, virt_to_page(&dn->data),
                                            dlen, offset_in_page(&dn->data),
                                            block);
        if (err) {
                ubifs_err(c, "fscrypt_decrypt_block_inplace() failed: %d", err);
                return err;
        }
        *out_len = clen;

        return 0;
}

const struct fscrypt_operations ubifs_crypt_operations = {
        .inode_info_offs        = (int)offsetof(struct ubifs_inode, i_crypt_info) -
                                  (int)offsetof(struct ubifs_inode, vfs_inode),
        .legacy_key_prefix      = "ubifs:",
        .get_context            = ubifs_crypt_get_context,
        .set_context            = ubifs_crypt_set_context,
        .empty_dir              = ubifs_crypt_empty_dir,
};