crypto: af_alg - User-space interface for Crypto API

This patch creates the backbone of the user-space interface for
the Crypto API, through a new socket family AF_ALG.

Each session corresponds to one or more connections obtained from
that socket.  The number depends on the number of inputs/outputs
of that particular type of operation.  For most types there will
be a s ingle connection/file descriptor that is used for both input
and output.  AEAD is one of the few that require two inputs.

Each algorithm type will provide its own implementation that plugs
into af_alg.  They're keyed using a string such as "skcipher" or
"hash".

IOW this patch only contains the boring bits that is required
to hold everything together.

Thakns to Miloslav Trmac for reviewing this and contributing
fixes and improvements.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: David S. Miller <davem@davemloft.net>
Tested-by: Martin Willi <martin@strongswan.org>

crypto/Kconfig

@@ -841,6 +841,9 @@ config CRYPTO_ANSI_CPRNG
 	  ANSI X9.31 A.2.4. Note that this option must be enabled if
 	  CRYPTO_FIPS is selected
 
+config CRYPTO_USER_API
+	tristate
+
 source "drivers/crypto/Kconfig"
 
 endif	# if CRYPTO

crypto/Makefile

@@ -85,6 +85,7 @@ obj-$(CONFIG_CRYPTO_RNG2) += krng.o
 obj-$(CONFIG_CRYPTO_ANSI_CPRNG) += ansi_cprng.o
 obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o
 obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o
+obj-$(CONFIG_CRYPTO_USER_API) += af_alg.o
 
 #
 # generic algorithms and the async_tx api

crypto/af_alg.c

@@ -0,0 +1,482 @@
+/*
+ * 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 <asm/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>
+
+struct alg_type_list {
+	const struct af_alg_type *type;
+	struct list_head list;
+};
+
+static atomic_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);
+
+	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;
+
+	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);

include/crypto/if_alg.h

@@ -0,0 +1,92 @@
+/*
+ * if_alg: User-space algorithm interface
+ *
+ * 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.
+ *
+ */
+
+#ifndef _CRYPTO_IF_ALG_H
+#define _CRYPTO_IF_ALG_H
+
+#include <linux/compiler.h>
+#include <linux/completion.h>
+#include <linux/if_alg.h>
+#include <linux/types.h>
+#include <net/sock.h>
+
+#define ALG_MAX_PAGES			16
+
+struct crypto_async_request;
+
+struct alg_sock {
+	/* struct sock must be the first member of struct alg_sock */
+	struct sock sk;
+
+	struct sock *parent;
+
+	const struct af_alg_type *type;
+	void *private;
+};
+
+struct af_alg_completion {
+	struct completion completion;
+	int err;
+};
+
+struct af_alg_control {
+	struct af_alg_iv *iv;
+	int op;
+};
+
+struct af_alg_type {
+	void *(*bind)(const char *name, u32 type, u32 mask);
+	void (*release)(void *private);
+	int (*setkey)(void *private, const u8 *key, unsigned int keylen);
+	int (*accept)(void *private, struct sock *sk);
+
+	struct proto_ops *ops;
+	struct module *owner;
+	char name[14];
+};
+
+struct af_alg_sgl {
+	struct scatterlist sg[ALG_MAX_PAGES];
+	struct page *pages[ALG_MAX_PAGES];
+};
+
+int af_alg_register_type(const struct af_alg_type *type);
+int af_alg_unregister_type(const struct af_alg_type *type);
+
+int af_alg_release(struct socket *sock);
+int af_alg_accept(struct sock *sk, struct socket *newsock);
+
+int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
+		   int write);
+void af_alg_free_sg(struct af_alg_sgl *sgl);
+
+int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con);
+
+int af_alg_wait_for_completion(int err, struct af_alg_completion *completion);
+void af_alg_complete(struct crypto_async_request *req, int err);
+
+static inline struct alg_sock *alg_sk(struct sock *sk)
+{
+	return (struct alg_sock *)sk;
+}
+
+static inline void af_alg_release_parent(struct sock *sk)
+{
+	sock_put(alg_sk(sk)->parent);
+}
+
+static inline void af_alg_init_completion(struct af_alg_completion *completion)
+{
+	init_completion(&completion->completion);
+}
+
+#endif	/* _CRYPTO_IF_ALG_H */

include/linux/if_alg.h

@@ -0,0 +1,40 @@
+/*
+ * if_alg: User-space algorithm interface
+ *
+ * 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.
+ *
+ */
+
+#ifndef _LINUX_IF_ALG_H
+#define _LINUX_IF_ALG_H
+
+#include <linux/types.h>
+
+struct sockaddr_alg {
+	__u16	salg_family;
+	__u8	salg_type[14];
+	__u32	salg_feat;
+	__u32	salg_mask;
+	__u8	salg_name[64];
+};
+
+struct af_alg_iv {
+	__u32	ivlen;
+	__u8	iv[0];
+};
+
+/* Socket options */
+#define ALG_SET_KEY			1
+#define ALG_SET_IV			2
+#define ALG_SET_OP			3
+
+/* Operations */
+#define ALG_OP_DECRYPT			0
+#define ALG_OP_ENCRYPT			1
+
+#endif	/* _LINUX_IF_ALG_H */