/*
   * algif_hash: User-space interface for hash algorithms
   *
   * This file provides the user-space API for hash algorithms.
   *
   * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option)
   * any later version.
   *
   */
  
  #include <crypto/hash.h>
  #include <crypto/if_alg.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/module.h>
  #include <linux/net.h>
  #include <net/sock.h>
  
  struct hash_ctx {
  	struct af_alg_sgl sgl;
  
  	u8 *result;
  
  	struct af_alg_completion completion;
  
  	unsigned int len;
  	bool more;
  
  	struct ahash_request req;
  };
  
  struct algif_hash_tfm {
  	struct crypto_ahash *hash;
  	bool has_key;
  };
  
  static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
  			size_t ignored)
  {
  	int limit = ALG_MAX_PAGES * PAGE_SIZE;
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct hash_ctx *ctx = ask->private;
  	long copied = 0;
  	int err;
  
  	if (limit > sk->sk_sndbuf)
  		limit = sk->sk_sndbuf;
  
  	lock_sock(sk);
  	if (!ctx->more) {
  		err = af_alg_wait_for_completion(crypto_ahash_init(&ctx->req),
  						&ctx->completion);
  		if (err)
  			goto unlock;
  	}
  
  	ctx->more = 0;
  
  	while (msg_data_left(msg)) {
  		int len = msg_data_left(msg);
  
  		if (len > limit)
  			len = limit;
  
  		len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len);
  		if (len < 0) {
  			err = copied ? 0 : len;
  			goto unlock;
  		}
  
  		ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
  
  		err = af_alg_wait_for_completion(crypto_ahash_update(&ctx->req),
  						 &ctx->completion);
  		af_alg_free_sg(&ctx->sgl);
  		if (err)
  			goto unlock;
  
  		copied += len;
  		iov_iter_advance(&msg->msg_iter, len);
  	}
  
  	err = 0;
  
  	ctx->more = msg->msg_flags & MSG_MORE;
  	if (!ctx->more) {
  		ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);
  		err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
  						 &ctx->completion);
  	}
  
  unlock:
  	release_sock(sk);
  
  	return err ?: copied;
  }
  
  static ssize_t hash_sendpage(struct socket *sock, struct page *page,
  			     int offset, size_t size, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct hash_ctx *ctx = ask->private;
  	int err;
  
  	if (flags & MSG_SENDPAGE_NOTLAST)
  		flags |= MSG_MORE;
  
  	lock_sock(sk);
  	sg_init_table(ctx->sgl.sg, 1);
  	sg_set_page(ctx->sgl.sg, page, size, offset);
  
  	ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, ctx->result, size);
  
  	if (!(flags & MSG_MORE)) {
  		if (ctx->more)
  			err = crypto_ahash_finup(&ctx->req);
  		else
  			err = crypto_ahash_digest(&ctx->req);
  	} else {
  		if (!ctx->more) {
  			err = crypto_ahash_init(&ctx->req);
  			err = af_alg_wait_for_completion(err, &ctx->completion);
  			if (err)
  				goto unlock;
  		}
  
  		err = crypto_ahash_update(&ctx->req);
  	}
  
  	err = af_alg_wait_for_completion(err, &ctx->completion);
  	if (err)
  		goto unlock;
  
  	ctx->more = flags & MSG_MORE;
  
  unlock:
  	release_sock(sk);
  
  	return err ?: size;
  }
  
  static int hash_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
  			int flags)
  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct hash_ctx *ctx = ask->private;
  	unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
  	int err;
  
  	if (len > ds)
  		len = ds;
  	else if (len < ds)
  		msg->msg_flags |= MSG_TRUNC;
  
  	lock_sock(sk);
  	if (ctx->more) {
  		ctx->more = 0;
  		ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);
  		err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
  						 &ctx->completion);
  		if (err)
  			goto unlock;
  	}
  
  	err = memcpy_to_msg(msg, ctx->result, len);
  
  unlock:
  	release_sock(sk);
  
  	return err ?: len;
  }
  
  static int hash_accept(struct socket *sock, struct socket *newsock, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  	struct hash_ctx *ctx = ask->private;
  	struct ahash_request *req = &ctx->req;
  	char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req))];
  	struct sock *sk2;
  	struct alg_sock *ask2;
  	struct hash_ctx *ctx2;
  	bool more;
  	int err;
  
  	lock_sock(sk);
  	more = ctx->more;
  	err = more ? crypto_ahash_export(req, state) : 0;
  	release_sock(sk);
  
  	if (err)
  		return err;
  
  	err = af_alg_accept(ask->parent, newsock);
  	if (err)
  		return err;
  
  	sk2 = newsock->sk;
  	ask2 = alg_sk(sk2);
  	ctx2 = ask2->private;
  	ctx2->more = more;
  
  	if (!more)
  		return err;
  
  	err = crypto_ahash_import(&ctx2->req, state);
  	if (err) {
  		sock_orphan(sk2);
  		sock_put(sk2);
  	}
  
  	return err;
  }
  
  static struct proto_ops algif_hash_ops = {
  	.family		=	PF_ALG,
  
  	.connect	=	sock_no_connect,
  	.socketpair	=	sock_no_socketpair,
  	.getname	=	sock_no_getname,
  	.ioctl		=	sock_no_ioctl,
  	.listen		=	sock_no_listen,
  	.shutdown	=	sock_no_shutdown,
  	.getsockopt	=	sock_no_getsockopt,
  	.mmap		=	sock_no_mmap,
  	.bind		=	sock_no_bind,
  	.setsockopt	=	sock_no_setsockopt,
  	.poll		=	sock_no_poll,
  
  	.release	=	af_alg_release,
  	.sendmsg	=	hash_sendmsg,
  	.sendpage	=	hash_sendpage,
  	.recvmsg	=	hash_recvmsg,
  	.accept		=	hash_accept,
  };
  
  static int hash_check_key(struct socket *sock)
  {
  	int err = 0;
  	struct sock *psk;
  	struct alg_sock *pask;
  	struct algif_hash_tfm *tfm;
  	struct sock *sk = sock->sk;
  	struct alg_sock *ask = alg_sk(sk);
  
  	lock_sock(sk);
  	if (ask->refcnt)
  		goto unlock_child;
  
  	psk = ask->parent;
  	pask = alg_sk(ask->parent);
  	tfm = pask->private;
  
  	err = -ENOKEY;
  	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
  	if (!tfm->has_key)
  		goto unlock;
  
  	if (!pask->refcnt++)
  		sock_hold(psk);
  
  	ask->refcnt = 1;
  	sock_put(psk);
  
  	err = 0;
  
  unlock:
  	release_sock(psk);
  unlock_child:
  	release_sock(sk);
  
  	return err;
  }
  
  static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
  			      size_t size)
  {
  	int err;
  
  	err = hash_check_key(sock);
  	if (err)
  		return err;
  
  	return hash_sendmsg(sock, msg, size);
  }
  
  static ssize_t hash_sendpage_nokey(struct socket *sock, struct page *page,
  				   int offset, size_t size, int flags)
  {
  	int err;
  
  	err = hash_check_key(sock);
  	if (err)
  		return err;
  
  	return hash_sendpage(sock, page, offset, size, flags);
  }
  
  static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
  			      size_t ignored, int flags)
  {
  	int err;
  
  	err = hash_check_key(sock);
  	if (err)
  		return err;
  
  	return hash_recvmsg(sock, msg, ignored, flags);
  }
  
  static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
  			     int flags)
  {
  	int err;
  
  	err = hash_check_key(sock);
  	if (err)
  		return err;
  
  	return hash_accept(sock, newsock, flags);
  }
  
  static struct proto_ops algif_hash_ops_nokey = {
  	.family		=	PF_ALG,
  
  	.connect	=	sock_no_connect,
  	.socketpair	=	sock_no_socketpair,
  	.getname	=	sock_no_getname,
  	.ioctl		=	sock_no_ioctl,
  	.listen		=	sock_no_listen,
  	.shutdown	=	sock_no_shutdown,
  	.getsockopt	=	sock_no_getsockopt,
  	.mmap		=	sock_no_mmap,
  	.bind		=	sock_no_bind,
  	.setsockopt	=	sock_no_setsockopt,
  	.poll		=	sock_no_poll,
  
  	.release	=	af_alg_release,
  	.sendmsg	=	hash_sendmsg_nokey,
  	.sendpage	=	hash_sendpage_nokey,
  	.recvmsg	=	hash_recvmsg_nokey,
  	.accept		=	hash_accept_nokey,
  };
  
  static void *hash_bind(const char *name, u32 type, u32 mask)
  {
  	struct algif_hash_tfm *tfm;
  	struct crypto_ahash *hash;
  
  	tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
  	if (!tfm)
  		return ERR_PTR(-ENOMEM);
  
  	hash = crypto_alloc_ahash(name, type, mask);
  	if (IS_ERR(hash)) {
  		kfree(tfm);
  		return ERR_CAST(hash);
  	}
  
  	tfm->hash = hash;
  
  	return tfm;
  }
  
  static void hash_release(void *private)
  {
  	struct algif_hash_tfm *tfm = private;
  
  	crypto_free_ahash(tfm->hash);
  	kfree(tfm);
  }
  
  static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
  {
  	struct algif_hash_tfm *tfm = private;
  	int err;
  
  	err = crypto_ahash_setkey(tfm->hash, key, keylen);
  	tfm->has_key = !err;
  
  	return err;
  }
  
  static void hash_sock_destruct(struct sock *sk)
  {
  	struct alg_sock *ask = alg_sk(sk);
  	struct hash_ctx *ctx = ask->private;
  
  	sock_kzfree_s(sk, ctx->result,
  		      crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req)));
  	sock_kfree_s(sk, ctx, ctx->len);
  	af_alg_release_parent(sk);
  }
  
  static int hash_accept_parent_nokey(void *private, struct sock *sk)
  {
  	struct hash_ctx *ctx;
  	struct alg_sock *ask = alg_sk(sk);
  	struct algif_hash_tfm *tfm = private;
  	struct crypto_ahash *hash = tfm->hash;
  	unsigned len = sizeof(*ctx) + crypto_ahash_reqsize(hash);
  	unsigned ds = crypto_ahash_digestsize(hash);
  
  	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
  	if (!ctx)
  		return -ENOMEM;
  
  	ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
  	if (!ctx->result) {
  		sock_kfree_s(sk, ctx, len);
  		return -ENOMEM;
  	}
  
  	memset(ctx->result, 0, ds);
  
  	ctx->len = len;
  	ctx->more = 0;
  	af_alg_init_completion(&ctx->completion);
  
  	ask->private = ctx;
  
  	ahash_request_set_tfm(&ctx->req, hash);
  	ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
  				   af_alg_complete, &ctx->completion);
  
  	sk->sk_destruct = hash_sock_destruct;
  
  	return 0;
  }
  
  static int hash_accept_parent(void *private, struct sock *sk)
  {
  	struct algif_hash_tfm *tfm = private;
  
  	if (!tfm->has_key && crypto_ahash_has_setkey(tfm->hash))
  		return -ENOKEY;
  
  	return hash_accept_parent_nokey(private, sk);
  }
  
  static const struct af_alg_type algif_type_hash = {
  	.bind		=	hash_bind,
  	.release	=	hash_release,
  	.setkey		=	hash_setkey,
  	.accept		=	hash_accept_parent,
  	.accept_nokey	=	hash_accept_parent_nokey,
  	.ops		=	&algif_hash_ops,
  	.ops_nokey	=	&algif_hash_ops_nokey,
  	.name		=	"hash",
  	.owner		=	THIS_MODULE
  };
  
  static int __init algif_hash_init(void)
  {
  	return af_alg_register_type(&algif_type_hash);
  }
  
  static void __exit algif_hash_exit(void)
  {
  	int err = af_alg_unregister_type(&algif_type_hash);
  	BUG_ON(err);
  }
  
  module_init(algif_hash_init);
  module_exit(algif_hash_exit);
  MODULE_LICENSE("GPL");