/*
   * Crypto user configuration API.
   *
   * Copyright (C) 2011 secunet Security Networks AG
   * Copyright (C) 2011 Steffen Klassert <steffen.klassert@secunet.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc.,
   * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
   */
  
  #include <linux/module.h>
  #include <linux/crypto.h>
  #include <linux/cryptouser.h>

  #include <linux/sched.h>

  #include <net/netlink.h>
  #include <linux/security.h>
  #include <net/net_namespace.h>

  #include <crypto/internal/aead.h>
  #include <crypto/internal/skcipher.h>

  #include <crypto/internal/rng.h>

  #include <crypto/akcipher.h>

  #include "internal.h"

  #define null_terminated(x)	(strnlen(x, sizeof(x)) < sizeof(x))

  static DEFINE_MUTEX(crypto_cfg_mutex);

  
  /* The crypto netlink socket */
  static struct sock *crypto_nlsk;
  
  struct crypto_dump_info {
  	struct sk_buff *in_skb;
  	struct sk_buff *out_skb;
  	u32 nlmsg_seq;
  	u16 nlmsg_flags;
  };
  
  static struct crypto_alg *crypto_alg_match(struct crypto_user_alg *p, int exact)
  {

  	struct crypto_alg *q, *alg = NULL;
  
  	down_read(&crypto_alg_sem);

  	list_for_each_entry(q, &crypto_alg_list, cra_list) {

  		int match = 0;

  
  		if ((q->cra_flags ^ p->cru_type) & p->cru_mask)
  			continue;
  
  		if (strlen(p->cru_driver_name))
  			match = !strcmp(q->cra_driver_name,
  					p->cru_driver_name);
  		else if (!exact)
  			match = !strcmp(q->cra_name, p->cru_name);

  		if (!match)
  			continue;
  
  		if (unlikely(!crypto_mod_get(q)))
  			continue;
  
  		alg = q;
  		break;

  	}
  
  	up_read(&crypto_alg_sem);
  
  	return alg;
  }

  static int crypto_report_cipher(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	struct crypto_report_cipher rcipher;

  	strncpy(rcipher.type, "cipher", sizeof(rcipher.type));

  
  	rcipher.blocksize = alg->cra_blocksize;
  	rcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
  	rcipher.max_keysize = alg->cra_cipher.cia_max_keysize;

  	if (nla_put(skb, CRYPTOCFGA_REPORT_CIPHER,
  		    sizeof(struct crypto_report_cipher), &rcipher))
  		goto nla_put_failure;

  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }

  static int crypto_report_comp(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	struct crypto_report_comp rcomp;

  	strncpy(rcomp.type, "compression", sizeof(rcomp.type));

  	if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
  		    sizeof(struct crypto_report_comp), &rcomp))
  		goto nla_put_failure;

  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }

  static int crypto_report_akcipher(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	struct crypto_report_akcipher rakcipher;
  
  	strncpy(rakcipher.type, "akcipher", sizeof(rakcipher.type));
  
  	if (nla_put(skb, CRYPTOCFGA_REPORT_AKCIPHER,
  		    sizeof(struct crypto_report_akcipher), &rakcipher))
  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }

  static int crypto_report_one(struct crypto_alg *alg,
  			     struct crypto_user_alg *ualg, struct sk_buff *skb)
  {

  	strncpy(ualg->cru_name, alg->cra_name, sizeof(ualg->cru_name));
  	strncpy(ualg->cru_driver_name, alg->cra_driver_name,
  		sizeof(ualg->cru_driver_name));
  	strncpy(ualg->cru_module_name, module_name(alg->cra_module),
  		sizeof(ualg->cru_module_name));
  
  	ualg->cru_type = 0;
  	ualg->cru_mask = 0;

  	ualg->cru_flags = alg->cra_flags;
  	ualg->cru_refcnt = atomic_read(&alg->cra_refcnt);

  	if (nla_put_u32(skb, CRYPTOCFGA_PRIORITY_VAL, alg->cra_priority))
  		goto nla_put_failure;

  	if (alg->cra_flags & CRYPTO_ALG_LARVAL) {
  		struct crypto_report_larval rl;

  		strncpy(rl.type, "larval", sizeof(rl.type));

  		if (nla_put(skb, CRYPTOCFGA_REPORT_LARVAL,
  			    sizeof(struct crypto_report_larval), &rl))
  			goto nla_put_failure;

  		goto out;
  	}

  	if (alg->cra_type && alg->cra_type->report) {
  		if (alg->cra_type->report(skb, alg))
  			goto nla_put_failure;

  
  		goto out;
  	}
  
  	switch (alg->cra_flags & (CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_LARVAL)) {
  	case CRYPTO_ALG_TYPE_CIPHER:
  		if (crypto_report_cipher(skb, alg))
  			goto nla_put_failure;
  
  		break;

  	case CRYPTO_ALG_TYPE_COMPRESS:
  		if (crypto_report_comp(skb, alg))
  			goto nla_put_failure;
  
  		break;

  
  	case CRYPTO_ALG_TYPE_AKCIPHER:
  		if (crypto_report_akcipher(skb, alg))
  			goto nla_put_failure;
  
  		break;

  	}

  out:

  	return 0;
  
  nla_put_failure:
  	return -EMSGSIZE;
  }
  
  static int crypto_report_alg(struct crypto_alg *alg,
  			     struct crypto_dump_info *info)
  {
  	struct sk_buff *in_skb = info->in_skb;
  	struct sk_buff *skb = info->out_skb;
  	struct nlmsghdr *nlh;
  	struct crypto_user_alg *ualg;
  	int err = 0;

  	nlh = nlmsg_put(skb, NETLINK_CB(in_skb).portid, info->nlmsg_seq,

  			CRYPTO_MSG_GETALG, sizeof(*ualg), info->nlmsg_flags);
  	if (!nlh) {
  		err = -EMSGSIZE;
  		goto out;
  	}
  
  	ualg = nlmsg_data(nlh);
  
  	err = crypto_report_one(alg, ualg, skb);
  	if (err) {
  		nlmsg_cancel(skb, nlh);
  		goto out;
  	}
  
  	nlmsg_end(skb, nlh);
  
  out:
  	return err;
  }
  
  static int crypto_report(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
  			 struct nlattr **attrs)
  {
  	struct crypto_user_alg *p = nlmsg_data(in_nlh);
  	struct crypto_alg *alg;
  	struct sk_buff *skb;
  	struct crypto_dump_info info;
  	int err;

  	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
  		return -EINVAL;

  	alg = crypto_alg_match(p, 0);

  	if (!alg)
  		return -ENOENT;

  	err = -ENOMEM;

  	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
  	if (!skb)

  		goto drop_alg;

  
  	info.in_skb = in_skb;
  	info.out_skb = skb;
  	info.nlmsg_seq = in_nlh->nlmsg_seq;
  	info.nlmsg_flags = 0;
  
  	err = crypto_report_alg(alg, &info);

  
  drop_alg:
  	crypto_mod_put(alg);

  	if (err)
  		return err;

  	return nlmsg_unicast(crypto_nlsk, skb, NETLINK_CB(in_skb).portid);

  }
  
  static int crypto_dump_report(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	struct crypto_alg *alg;
  	struct crypto_dump_info info;
  	int err;
  
  	if (cb->args[0])
  		goto out;
  
  	cb->args[0] = 1;
  
  	info.in_skb = cb->skb;
  	info.out_skb = skb;
  	info.nlmsg_seq = cb->nlh->nlmsg_seq;
  	info.nlmsg_flags = NLM_F_MULTI;
  
  	list_for_each_entry(alg, &crypto_alg_list, cra_list) {
  		err = crypto_report_alg(alg, &info);
  		if (err)
  			goto out_err;
  	}
  
  out:
  	return skb->len;
  out_err:
  	return err;
  }
  
  static int crypto_dump_report_done(struct netlink_callback *cb)
  {
  	return 0;
  }
  
  static int crypto_update_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     struct nlattr **attrs)
  {
  	struct crypto_alg *alg;
  	struct crypto_user_alg *p = nlmsg_data(nlh);
  	struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];
  	LIST_HEAD(list);

  	if (!netlink_capable(skb, CAP_NET_ADMIN))

  		return -EPERM;

  	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
  		return -EINVAL;

  	if (priority && !strlen(p->cru_driver_name))
  		return -EINVAL;
  
  	alg = crypto_alg_match(p, 1);
  	if (!alg)
  		return -ENOENT;
  
  	down_write(&crypto_alg_sem);
  
  	crypto_remove_spawns(alg, &list, NULL);
  
  	if (priority)
  		alg->cra_priority = nla_get_u32(priority);
  
  	up_write(&crypto_alg_sem);

  	crypto_mod_put(alg);

  	crypto_remove_final(&list);
  
  	return 0;
  }
  
  static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
  			  struct nlattr **attrs)
  {
  	struct crypto_alg *alg;
  	struct crypto_user_alg *p = nlmsg_data(nlh);

  	int err;

  	if (!netlink_capable(skb, CAP_NET_ADMIN))

  		return -EPERM;

  	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
  		return -EINVAL;

  	alg = crypto_alg_match(p, 1);
  	if (!alg)
  		return -ENOENT;
  
  	/* We can not unregister core algorithms such as aes-generic.
  	 * We would loose the reference in the crypto_alg_list to this algorithm
  	 * if we try to unregister. Unregistering such an algorithm without
  	 * removing the module is not possible, so we restrict to crypto
  	 * instances that are build from templates. */

  	err = -EINVAL;

  	if (!(alg->cra_flags & CRYPTO_ALG_INSTANCE))

  		goto drop_alg;

  	err = -EBUSY;
  	if (atomic_read(&alg->cra_refcnt) > 2)
  		goto drop_alg;

  	err = crypto_unregister_instance((struct crypto_instance *)alg);
  
  drop_alg:
  	crypto_mod_put(alg);
  	return err;

  }

  static struct crypto_alg *crypto_user_skcipher_alg(const char *name, u32 type,
  						   u32 mask)
  {
  	int err;
  	struct crypto_alg *alg;
  
  	type = crypto_skcipher_type(type);
  	mask = crypto_skcipher_mask(mask);
  
  	for (;;) {
  		alg = crypto_lookup_skcipher(name,  type, mask);
  		if (!IS_ERR(alg))
  			return alg;
  
  		err = PTR_ERR(alg);
  		if (err != -EAGAIN)
  			break;
  		if (signal_pending(current)) {
  			err = -EINTR;
  			break;
  		}
  	}
  
  	return ERR_PTR(err);
  }
  
  static struct crypto_alg *crypto_user_aead_alg(const char *name, u32 type,
  					       u32 mask)
  {
  	int err;
  	struct crypto_alg *alg;
  
  	type &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
  	type |= CRYPTO_ALG_TYPE_AEAD;
  	mask &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
  	mask |= CRYPTO_ALG_TYPE_MASK;
  
  	for (;;) {
  		alg = crypto_lookup_aead(name,  type, mask);
  		if (!IS_ERR(alg))
  			return alg;
  
  		err = PTR_ERR(alg);
  		if (err != -EAGAIN)
  			break;
  		if (signal_pending(current)) {
  			err = -EINTR;
  			break;
  		}
  	}
  
  	return ERR_PTR(err);
  }

  static int crypto_add_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
  			  struct nlattr **attrs)
  {

  	int exact = 0;

  	const char *name;
  	struct crypto_alg *alg;
  	struct crypto_user_alg *p = nlmsg_data(nlh);
  	struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];

  	if (!netlink_capable(skb, CAP_NET_ADMIN))

  		return -EPERM;

  	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
  		return -EINVAL;

  	if (strlen(p->cru_driver_name))
  		exact = 1;
  
  	if (priority && !exact)
  		return -EINVAL;
  
  	alg = crypto_alg_match(p, exact);

  	if (alg) {
  		crypto_mod_put(alg);

  		return -EEXIST;

  	}

  
  	if (strlen(p->cru_driver_name))
  		name = p->cru_driver_name;
  	else
  		name = p->cru_name;

  	switch (p->cru_type & p->cru_mask & CRYPTO_ALG_TYPE_MASK) {
  	case CRYPTO_ALG_TYPE_AEAD:
  		alg = crypto_user_aead_alg(name, p->cru_type, p->cru_mask);
  		break;
  	case CRYPTO_ALG_TYPE_GIVCIPHER:
  	case CRYPTO_ALG_TYPE_BLKCIPHER:
  	case CRYPTO_ALG_TYPE_ABLKCIPHER:
  		alg = crypto_user_skcipher_alg(name, p->cru_type, p->cru_mask);
  		break;
  	default:
  		alg = crypto_alg_mod_lookup(name, p->cru_type, p->cru_mask);
  	}

  	if (IS_ERR(alg))
  		return PTR_ERR(alg);
  
  	down_write(&crypto_alg_sem);
  
  	if (priority)
  		alg->cra_priority = nla_get_u32(priority);
  
  	up_write(&crypto_alg_sem);
  
  	crypto_mod_put(alg);
  
  	return 0;
  }

  static int crypto_del_rng(struct sk_buff *skb, struct nlmsghdr *nlh,
  			  struct nlattr **attrs)
  {
  	if (!netlink_capable(skb, CAP_NET_ADMIN))
  		return -EPERM;
  	return crypto_del_default_rng();
  }

  #define MSGSIZE(type) sizeof(struct type)
  
  static const int crypto_msg_min[CRYPTO_NR_MSGTYPES] = {
  	[CRYPTO_MSG_NEWALG	- CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
  	[CRYPTO_MSG_DELALG	- CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
  	[CRYPTO_MSG_UPDATEALG	- CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),

  	[CRYPTO_MSG_DELRNG	- CRYPTO_MSG_BASE] = 0,

  };
  
  static const struct nla_policy crypto_policy[CRYPTOCFGA_MAX+1] = {
  	[CRYPTOCFGA_PRIORITY_VAL]   = { .type = NLA_U32},
  };
  
  #undef MSGSIZE

  static const struct crypto_link {

  	int (*doit)(struct sk_buff *, struct nlmsghdr *, struct nlattr **);
  	int (*dump)(struct sk_buff *, struct netlink_callback *);
  	int (*done)(struct netlink_callback *);
  } crypto_dispatch[CRYPTO_NR_MSGTYPES] = {
  	[CRYPTO_MSG_NEWALG	- CRYPTO_MSG_BASE] = { .doit = crypto_add_alg},
  	[CRYPTO_MSG_DELALG	- CRYPTO_MSG_BASE] = { .doit = crypto_del_alg},
  	[CRYPTO_MSG_UPDATEALG	- CRYPTO_MSG_BASE] = { .doit = crypto_update_alg},
  	[CRYPTO_MSG_GETALG	- CRYPTO_MSG_BASE] = { .doit = crypto_report,
  						       .dump = crypto_dump_report,
  						       .done = crypto_dump_report_done},

  	[CRYPTO_MSG_DELRNG	- CRYPTO_MSG_BASE] = { .doit = crypto_del_rng },

  };
  
  static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
  {
  	struct nlattr *attrs[CRYPTOCFGA_MAX+1];

  	const struct crypto_link *link;

  	int type, err;
  
  	type = nlh->nlmsg_type;
  	if (type > CRYPTO_MSG_MAX)
  		return -EINVAL;
  
  	type -= CRYPTO_MSG_BASE;
  	link = &crypto_dispatch[type];

  	if ((type == (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE) &&
  	    (nlh->nlmsg_flags & NLM_F_DUMP))) {

  		struct crypto_alg *alg;
  		u16 dump_alloc = 0;

  		if (link->dump == NULL)
  			return -EINVAL;

  
  		list_for_each_entry(alg, &crypto_alg_list, cra_list)
  			dump_alloc += CRYPTO_REPORT_MAXSIZE;

  		{
  			struct netlink_dump_control c = {
  				.dump = link->dump,
  				.done = link->done,

  				.min_dump_alloc = dump_alloc,

  			};
  			return netlink_dump_start(crypto_nlsk, skb, nlh, &c);
  		}

  	}
  
  	err = nlmsg_parse(nlh, crypto_msg_min[type], attrs, CRYPTOCFGA_MAX,
  			  crypto_policy);
  	if (err < 0)
  		return err;
  
  	if (link->doit == NULL)
  		return -EINVAL;
  
  	return link->doit(skb, nlh, attrs);
  }
  
  static void crypto_netlink_rcv(struct sk_buff *skb)
  {
  	mutex_lock(&crypto_cfg_mutex);
  	netlink_rcv_skb(skb, &crypto_user_rcv_msg);
  	mutex_unlock(&crypto_cfg_mutex);
  }
  
  static int __init crypto_user_init(void)
  {

  	struct netlink_kernel_cfg cfg = {
  		.input	= crypto_netlink_rcv,
  	};

  	crypto_nlsk = netlink_kernel_create(&init_net, NETLINK_CRYPTO, &cfg);

  	if (!crypto_nlsk)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void __exit crypto_user_exit(void)
  {
  	netlink_kernel_release(crypto_nlsk);
  }
  
  module_init(crypto_user_init);
  module_exit(crypto_user_exit);
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
  MODULE_DESCRIPTION("Crypto userspace configuration API");

  MODULE_ALIAS("net-pf-16-proto-21");