Quelle algif_skcipher.c Sprache: C

// 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 <herbert@gondor.apana.org.au>
*
* 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");

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