af_alg.c

/*
 * af_alg: User-space algorithm interface
 *
 * This file provides the user-space API for 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 <linux/atomic.h>
#include <crypto/if_alg.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/rwsem.h>
#include <linux/security.h>

struct alg_type_list {
	const struct af_alg_type *type;
	struct list_head list;
};

static atomic_long_t alg_memory_allocated;

static struct proto alg_proto = {
	.name			= "ALG",
	.owner			= THIS_MODULE,
	.memory_allocated	= &alg_memory_allocated,
	.obj_size		= sizeof(struct alg_sock),
};

static LIST_HEAD(alg_types);
static DECLARE_RWSEM(alg_types_sem);

static const struct af_alg_type *alg_get_type(const char *name)
{
	const struct af_alg_type *type = ERR_PTR(-ENOENT);
	struct alg_type_list *node;

	down_read(&alg_types_sem);
	list_for_each_entry(node, &alg_types, list) {
		if (strcmp(node->type->name, name))
			continue;

		if (try_module_get(node->type->owner))
			type = node->type;
		break;
	}
	up_read(&alg_types_sem);

	return type;
}

int af_alg_register_type(const struct af_alg_type *type)
{
	struct alg_type_list *node;
	int err = -EEXIST;

	down_write(&alg_types_sem);
	list_for_each_entry(node, &alg_types, list) {
		if (!strcmp(node->type->name, type->name))
			goto unlock;
	}

	node = kmalloc(sizeof(*node), GFP_KERNEL);
	err = -ENOMEM;
	if (!node)
		goto unlock;

	type->ops->owner = THIS_MODULE;
	node->type = type;
	list_add(&node->list, &alg_types);
	err = 0;

unlock:
	up_write(&alg_types_sem);

	return err;
}
EXPORT_SYMBOL_GPL(af_alg_register_type);

int af_alg_unregister_type(const struct af_alg_type *type)
{
	struct alg_type_list *node;
	int err = -ENOENT;

	down_write(&alg_types_sem);
	list_for_each_entry(node, &alg_types, list) {
		if (strcmp(node->type->name, type->name))
			continue;

		list_del(&node->list);
		kfree(node);
		err = 0;
		break;
	}
	up_write(&alg_types_sem);

	return err;
}
EXPORT_SYMBOL_GPL(af_alg_unregister_type);

static void alg_do_release(const struct af_alg_type *type, void *private)
{
	if (!type)
		return;

	type->release(private);
	module_put(type->owner);
}

int af_alg_release(struct socket *sock)
{
	if (sock->sk)
		sock_put(sock->sk);
	return 0;
}
EXPORT_SYMBOL_GPL(af_alg_release);

static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	struct sockaddr_alg *sa = (void *)uaddr;
	const struct af_alg_type *type;
	void *private;

	if (sock->state == SS_CONNECTED)
		return -EINVAL;

	if (addr_len != sizeof(*sa))
		return -EINVAL;

	sa->salg_type[sizeof(sa->salg_type) - 1] = 0;
	sa->salg_name[sizeof(sa->salg_name) - 1] = 0;

	type = alg_get_type(sa->salg_type);
	if (IS_ERR(type) && PTR_ERR(type) == -ENOENT) {
		request_module("algif-%s", sa->salg_type);
		type = alg_get_type(sa->salg_type);
	}

	if (IS_ERR(type))
		return PTR_ERR(type);

	private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);
	if (IS_ERR(private)) {
		module_put(type->owner);
		return PTR_ERR(private);
	}

	lock_sock(sk);

	swap(ask->type, type);
	swap(ask->private, private);

	release_sock(sk);

	alg_do_release(type, private);

	return 0;
}

static int alg_setkey(struct sock *sk, char __user *ukey,
		      unsigned int keylen)
{
	struct alg_sock *ask = alg_sk(sk);
	const struct af_alg_type *type = ask->type;
	u8 *key;
	int err;

	key = sock_kmalloc(sk, keylen, GFP_KERNEL);
	if (!key)
		return -ENOMEM;

	err = -EFAULT;
	if (copy_from_user(key, ukey, keylen))
		goto out;

	err = type->setkey(ask->private, key, keylen);

out:
	sock_kfree_s(sk, key, keylen);

	return err;
}

static int alg_setsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, unsigned int optlen)
{
	struct sock *sk = sock->sk;
	struct alg_sock *ask = alg_sk(sk);
	const struct af_alg_type *type;
	int err = -ENOPROTOOPT;

	lock_sock(sk);
	type = ask->type;

	if (level != SOL_ALG || !type)
		goto unlock;

	switch (optname) {
	case ALG_SET_KEY:
		if (sock->state == SS_CONNECTED)
			goto unlock;
		if (!type->setkey)
			goto unlock;

		err = alg_setkey(sk, optval, optlen);
	}

unlock:
	release_sock(sk);

	return err;
}

int af_alg_accept(struct sock *sk, struct socket *newsock)
{
	struct alg_sock *ask = alg_sk(sk);
	const struct af_alg_type *type;
	struct sock *sk2;
	int err;

	lock_sock(sk);
	type = ask->type;

	err = -EINVAL;
	if (!type)
		goto unlock;

	sk2 = sk_alloc(sock_net(sk), PF_ALG, GFP_KERNEL, &alg_proto);
	err = -ENOMEM;
	if (!sk2)
		goto unlock;

	sock_init_data(newsock, sk2);
	sock_graft(sk2, newsock);
	security_sk_clone(sk, sk2);

	err = type->accept(ask->private, sk2);
	if (err) {
		sk_free(sk2);
		goto unlock;
	}

	sk2->sk_family = PF_ALG;

	sock_hold(sk);
	alg_sk(sk2)->parent = sk;
	alg_sk(sk2)->type = type;

	newsock->ops = type->ops;
	newsock->state = SS_CONNECTED;

	err = 0;

unlock:
	release_sock(sk);

	return err;
}
EXPORT_SYMBOL_GPL(af_alg_accept);

static int alg_accept(struct socket *sock, struct socket *newsock, int flags)
{
	return af_alg_accept(sock->sk, newsock);
}

static const struct proto_ops alg_proto_ops = {
	.family		=	PF_ALG,
	.owner		=	THIS_MODULE,

	.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,
	.sendpage	=	sock_no_sendpage,
	.sendmsg	=	sock_no_sendmsg,
	.recvmsg	=	sock_no_recvmsg,
	.poll		=	sock_no_poll,

	.bind		=	alg_bind,
	.release	=	af_alg_release,
	.setsockopt	=	alg_setsockopt,
	.accept		=	alg_accept,
};

static void alg_sock_destruct(struct sock *sk)
{
	struct alg_sock *ask = alg_sk(sk);

	alg_do_release(ask->type, ask->private);
}

static int alg_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	struct sock *sk;
	int err;

	if (sock->type != SOCK_SEQPACKET)
		return -ESOCKTNOSUPPORT;
	if (protocol != 0)
		return -EPROTONOSUPPORT;

	err = -ENOMEM;
	sk = sk_alloc(net, PF_ALG, GFP_KERNEL, &alg_proto);
	if (!sk)
		goto out;

	sock->ops = &alg_proto_ops;
	sock_init_data(sock, sk);

	sk->sk_family = PF_ALG;
	sk->sk_destruct = alg_sock_destruct;

	return 0;
out:
	return err;
}

static const struct net_proto_family alg_family = {
	.family	=	PF_ALG,
	.create	=	alg_create,
	.owner	=	THIS_MODULE,
};

int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
		   int write)
{
	unsigned long from = (unsigned long)addr;
	unsigned long npages;
	unsigned off;
	int err;
	int i;

	err = -EFAULT;
	if (!access_ok(write ? VERIFY_READ : VERIFY_WRITE, addr, len))
		goto out;

	off = from & ~PAGE_MASK;
	npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	if (npages > ALG_MAX_PAGES)
		npages = ALG_MAX_PAGES;

	err = get_user_pages_fast(from, npages, write, sgl->pages);
	if (err < 0)
		goto out;

	npages = err;
	err = -EINVAL;
	if (WARN_ON(npages == 0))
		goto out;

	err = 0;

	sg_init_table(sgl->sg, npages);

	for (i = 0; i < npages; i++) {
		int plen = min_t(int, len, PAGE_SIZE - off);

		sg_set_page(sgl->sg + i, sgl->pages[i], plen, off);

		off = 0;
		len -= plen;
		err += plen;
	}

out:
	return err;
}
EXPORT_SYMBOL_GPL(af_alg_make_sg);

void af_alg_free_sg(struct af_alg_sgl *sgl)
{
	int i;

	i = 0;
	do {
		put_page(sgl->pages[i]);
	} while (!sg_is_last(sgl->sg + (i++)));
}
EXPORT_SYMBOL_GPL(af_alg_free_sg);

int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con)
{
	struct cmsghdr *cmsg;

	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
		if (!CMSG_OK(msg, cmsg))
			return -EINVAL;
		if (cmsg->cmsg_level != SOL_ALG)
			continue;

		switch(cmsg->cmsg_type) {
		case ALG_SET_IV:
			if (cmsg->cmsg_len < CMSG_LEN(sizeof(*con->iv)))
				return -EINVAL;
			con->iv = (void *)CMSG_DATA(cmsg);
			if (cmsg->cmsg_len < CMSG_LEN(con->iv->ivlen +
						      sizeof(*con->iv)))
				return -EINVAL;
			break;

		case ALG_SET_OP:
			if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
				return -EINVAL;
			con->op = *(u32 *)CMSG_DATA(cmsg);
			break;

		default:
			return -EINVAL;
		}
	}

	return 0;
}
EXPORT_SYMBOL_GPL(af_alg_cmsg_send);

int af_alg_wait_for_completion(int err, struct af_alg_completion *completion)
{
	switch (err) {
	case -EINPROGRESS:
	case -EBUSY:
		wait_for_completion(&completion->completion);
		INIT_COMPLETION(completion->completion);
		err = completion->err;
		break;
	};

	return err;
}
EXPORT_SYMBOL_GPL(af_alg_wait_for_completion);

void af_alg_complete(struct crypto_async_request *req, int err)
{
	struct af_alg_completion *completion = req->data;

	if (err == -EINPROGRESS)
		return;

	completion->err = err;
	complete(&completion->completion);
}
EXPORT_SYMBOL_GPL(af_alg_complete);

static int __init af_alg_init(void)
{
	int err = proto_register(&alg_proto, 0);

	if (err)
		goto out;

	err = sock_register(&alg_family);
	if (err != 0)
		goto out_unregister_proto;

out:
	return err;

out_unregister_proto:
	proto_unregister(&alg_proto);
	goto out;
}

static void __exit af_alg_exit(void)
{
	sock_unregister(PF_ALG);
	proto_unregister(&alg_proto);
}

module_init(af_alg_init);
module_exit(af_alg_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(AF_ALG);