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algif_skcipher.c
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algif_skcipher.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* algif_skcipher: User-space interface for skcipher algorithms
*
* This file provides the user-space API for symmetric key ciphers.
*
* Copyright (c) 2010 Herbert Xu <[email protected]>
*
* The following concept of the memory management is used:
*
* The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
* filled by user space with the data submitted via sendmsg. Filling up the TX
* SGL does not cause a crypto operation -- the data will only be tracked by
* the kernel. Upon receipt of one recvmsg call, the caller must provide a
* buffer which is tracked with the RX SGL.
*
* During the processing of the recvmsg operation, the cipher request is
* allocated and prepared. As part of the recvmsg operation, the processed
* TX buffers are extracted from the TX SGL into a separate SGL.
*
* After the completion of the crypto operation, the RX SGL and the cipher
* request is released. The extracted TX SGL parts are released together with
* the RX SGL release.
*/
#include <crypto/scatterwalk.h>
#include <crypto/skcipher.h>
#include <crypto/if_alg.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/net.h>
#include <net/sock.h>
static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
size_t size)
{
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct sock *psk = ask->parent;
struct alg_sock *pask = alg_sk(psk);
struct crypto_skcipher *tfm = pask->private;
unsigned ivsize = crypto_skcipher_ivsize(tfm);
return af_alg_sendmsg(sock, msg, size, ivsize);
}
static int algif_skcipher_export(struct sock *sk, struct skcipher_request *req)
{
struct alg_sock *ask = alg_sk(sk);
struct crypto_skcipher *tfm;
struct af_alg_ctx *ctx;
struct alg_sock *pask;
unsigned statesize;
struct sock *psk;
int err;
if (!(req->base.flags & CRYPTO_SKCIPHER_REQ_NOTFINAL))
return 0;
ctx = ask->private;
psk = ask->parent;
pask = alg_sk(psk);
tfm = pask->private;
statesize = crypto_skcipher_statesize(tfm);
ctx->state = sock_kmalloc(sk, statesize, GFP_ATOMIC);
if (!ctx->state)
return -ENOMEM;
err = crypto_skcipher_export(req, ctx->state);
if (err) {
sock_kzfree_s(sk, ctx->state, statesize);
ctx->state = NULL;
}
return err;
}
static void algif_skcipher_done(void *data, int err)
{
struct af_alg_async_req *areq = data;
struct sock *sk = areq->sk;
if (err)
goto out;
err = algif_skcipher_export(sk, &areq->cra_u.skcipher_req);
out:
af_alg_async_cb(data, err);
}
static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
size_t ignored, int flags)
{
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct sock *psk = ask->parent;
struct alg_sock *pask = alg_sk(psk);
struct af_alg_ctx *ctx = ask->private;
struct crypto_skcipher *tfm = pask->private;
unsigned int bs = crypto_skcipher_chunksize(tfm);
struct af_alg_async_req *areq;
unsigned cflags = 0;
int err = 0;
size_t len = 0;
if (!ctx->init || (ctx->more && ctx->used < bs)) {
err = af_alg_wait_for_data(sk, flags, bs);
if (err)
return err;
}
/* Allocate cipher request for current operation. */
areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
crypto_skcipher_reqsize(tfm));
if (IS_ERR(areq))
return PTR_ERR(areq);
/* convert iovecs of output buffers into RX SGL */
err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
if (err)
goto free;
/*
* If more buffers are to be expected to be processed, process only
* full block size buffers.
*/
if (ctx->more || len < ctx->used) {
len -= len % bs;
cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL;
}
/*
* Create a per request TX SGL for this request which tracks the
* SG entries from the global TX SGL.
*/
areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
if (!areq->tsgl_entries)
areq->tsgl_entries = 1;
areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
areq->tsgl_entries),
GFP_KERNEL);
if (!areq->tsgl) {
err = -ENOMEM;
goto free;
}
sg_init_table(areq->tsgl, areq->tsgl_entries);
af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
/* Initialize the crypto operation */
skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv);
if (ctx->state) {
err = crypto_skcipher_import(&areq->cra_u.skcipher_req,
ctx->state);
sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
ctx->state = NULL;
if (err)
goto free;
cflags |= CRYPTO_SKCIPHER_REQ_CONT;
}
if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
/* AIO operation */
sock_hold(sk);
areq->iocb = msg->msg_iocb;
/* Remember output size that will be generated. */
areq->outlen = len;
skcipher_request_set_callback(&areq->cra_u.skcipher_req,
cflags |
CRYPTO_TFM_REQ_MAY_SLEEP,
algif_skcipher_done, areq);
err = ctx->enc ?
crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
/* AIO operation in progress */
if (err == -EINPROGRESS)
return -EIOCBQUEUED;
sock_put(sk);
} else {
/* Synchronous operation */
skcipher_request_set_callback(&areq->cra_u.skcipher_req,
cflags |
CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &ctx->wait);
err = crypto_wait_req(ctx->enc ?
crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
&ctx->wait);
if (!err)
err = algif_skcipher_export(
sk, &areq->cra_u.skcipher_req);
}
free:
af_alg_free_resources(areq);
return err ? err : len;
}
static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
size_t ignored, int flags)
{
struct sock *sk = sock->sk;
int ret = 0;
lock_sock(sk);
while (msg_data_left(msg)) {
int err = _skcipher_recvmsg(sock, msg, ignored, flags);
/*
* This error covers -EIOCBQUEUED which implies that we can
* only handle one AIO request. If the caller wants to have
* multiple AIO requests in parallel, he must make multiple
* separate AIO calls.
*
* Also return the error if no data has been processed so far.
*/
if (err <= 0) {
if (err == -EIOCBQUEUED || !ret)
ret = err;
goto out;
}
ret += err;
}
out:
af_alg_wmem_wakeup(sk);
release_sock(sk);
return ret;
}
static struct proto_ops algif_skcipher_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,
.mmap = sock_no_mmap,
.bind = sock_no_bind,
.accept = sock_no_accept,
.release = af_alg_release,
.sendmsg = skcipher_sendmsg,
.recvmsg = skcipher_recvmsg,
.poll = af_alg_poll,
};
static int skcipher_check_key(struct socket *sock)
{
int err = 0;
struct sock *psk;
struct alg_sock *pask;
struct crypto_skcipher *tfm;
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
lock_sock(sk);
if (!atomic_read(&ask->nokey_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 (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
goto unlock;
atomic_dec(&pask->nokey_refcnt);
atomic_set(&ask->nokey_refcnt, 0);
err = 0;
unlock:
release_sock(psk);
unlock_child:
release_sock(sk);
return err;
}
static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
size_t size)
{
int err;
err = skcipher_check_key(sock);
if (err)
return err;
return skcipher_sendmsg(sock, msg, size);
}
static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
size_t ignored, int flags)
{
int err;
err = skcipher_check_key(sock);
if (err)
return err;
return skcipher_recvmsg(sock, msg, ignored, flags);
}
static struct proto_ops algif_skcipher_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,
.mmap = sock_no_mmap,
.bind = sock_no_bind,
.accept = sock_no_accept,
.release = af_alg_release,
.sendmsg = skcipher_sendmsg_nokey,
.recvmsg = skcipher_recvmsg_nokey,
.poll = af_alg_poll,
};
static void *skcipher_bind(const char *name, u32 type, u32 mask)
{
return crypto_alloc_skcipher(name, type, mask);
}
static void skcipher_release(void *private)
{
crypto_free_skcipher(private);
}
static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
{
return crypto_skcipher_setkey(private, key, keylen);
}
static void skcipher_sock_destruct(struct sock *sk)
{
struct alg_sock *ask = alg_sk(sk);
struct af_alg_ctx *ctx = ask->private;
struct sock *psk = ask->parent;
struct alg_sock *pask = alg_sk(psk);
struct crypto_skcipher *tfm = pask->private;
af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
if (ctx->state)
sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
sock_kfree_s(sk, ctx, ctx->len);
af_alg_release_parent(sk);
}
static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
{
struct af_alg_ctx *ctx;
struct alg_sock *ask = alg_sk(sk);
struct crypto_skcipher *tfm = private;
unsigned int len = sizeof(*ctx);
ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
return -ENOMEM;
memset(ctx, 0, len);
ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
GFP_KERNEL);
if (!ctx->iv) {
sock_kfree_s(sk, ctx, len);
return -ENOMEM;
}
memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
INIT_LIST_HEAD(&ctx->tsgl_list);
ctx->len = len;
crypto_init_wait(&ctx->wait);
ask->private = ctx;
sk->sk_destruct = skcipher_sock_destruct;
return 0;
}
static int skcipher_accept_parent(void *private, struct sock *sk)
{
struct crypto_skcipher *tfm = private;
if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
return -ENOKEY;
return skcipher_accept_parent_nokey(private, sk);
}
static const struct af_alg_type algif_type_skcipher = {
.bind = skcipher_bind,
.release = skcipher_release,
.setkey = skcipher_setkey,
.accept = skcipher_accept_parent,
.accept_nokey = skcipher_accept_parent_nokey,
.ops = &algif_skcipher_ops,
.ops_nokey = &algif_skcipher_ops_nokey,
.name = "skcipher",
.owner = THIS_MODULE
};
static int __init algif_skcipher_init(void)
{
return af_alg_register_type(&algif_type_skcipher);
}
static void __exit algif_skcipher_exit(void)
{
int err = af_alg_unregister_type(&algif_type_skcipher);
BUG_ON(err);
}
module_init(algif_skcipher_init);
module_exit(algif_skcipher_exit);
MODULE_DESCRIPTION("Userspace interface for skcipher algorithms");
MODULE_LICENSE("GPL");