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![David Howells](/assets/img/avatar_default.png)
The 'MSG_MORE' state of the previous sendmsg() is fetched without the
socket lock held, so two sendmsg calls can race. This can be seen with a
large sendfile() as that now does a series of sendmsg() calls, and if a
write() comes in on the same socket at an inopportune time, it can flip the
state.
Fix this by moving the fetch of ctx->more inside the socket lock.
Fixes: c662b043cd
("crypto: af_alg/hash: Support MSG_SPLICE_PAGES")
Reported-by: syzbot+689ec3afb1ef07b766b2@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/000000000000554b8205ffdea64e@google.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: syzbot+689ec3afb1ef07b766b2@syzkaller.appspotmail.com
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: Paolo Abeni <pabeni@redhat.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
473 lines
9.6 KiB
C
473 lines
9.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* algif_hash: User-space interface for hash algorithms
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*
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* This file provides the user-space API for hash algorithms.
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*
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* Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#include <crypto/hash.h>
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#include <crypto/if_alg.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/net.h>
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#include <net/sock.h>
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struct hash_ctx {
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struct af_alg_sgl sgl;
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u8 *result;
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struct crypto_wait wait;
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unsigned int len;
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bool more;
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struct ahash_request req;
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};
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static int hash_alloc_result(struct sock *sk, struct hash_ctx *ctx)
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{
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unsigned ds;
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if (ctx->result)
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return 0;
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ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
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ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
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if (!ctx->result)
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return -ENOMEM;
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memset(ctx->result, 0, ds);
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return 0;
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}
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static void hash_free_result(struct sock *sk, struct hash_ctx *ctx)
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{
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unsigned ds;
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if (!ctx->result)
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return;
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ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
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sock_kzfree_s(sk, ctx->result, ds);
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ctx->result = NULL;
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}
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static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
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size_t ignored)
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{
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struct sock *sk = sock->sk;
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struct alg_sock *ask = alg_sk(sk);
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struct hash_ctx *ctx = ask->private;
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ssize_t copied = 0;
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size_t len, max_pages, npages;
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bool continuing, need_init = false;
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int err;
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max_pages = min_t(size_t, ALG_MAX_PAGES,
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DIV_ROUND_UP(sk->sk_sndbuf, PAGE_SIZE));
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lock_sock(sk);
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continuing = ctx->more;
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if (!continuing) {
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/* Discard a previous request that wasn't marked MSG_MORE. */
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hash_free_result(sk, ctx);
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if (!msg_data_left(msg))
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goto done; /* Zero-length; don't start new req */
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need_init = true;
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} else if (!msg_data_left(msg)) {
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/*
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* No data - finalise the prev req if MSG_MORE so any error
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* comes out here.
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*/
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if (!(msg->msg_flags & MSG_MORE)) {
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err = hash_alloc_result(sk, ctx);
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if (err)
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goto unlock_free;
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ahash_request_set_crypt(&ctx->req, NULL,
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ctx->result, 0);
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err = crypto_wait_req(crypto_ahash_final(&ctx->req),
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&ctx->wait);
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if (err)
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goto unlock_free;
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}
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goto done_more;
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}
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while (msg_data_left(msg)) {
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ctx->sgl.sgt.sgl = ctx->sgl.sgl;
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ctx->sgl.sgt.nents = 0;
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ctx->sgl.sgt.orig_nents = 0;
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err = -EIO;
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npages = iov_iter_npages(&msg->msg_iter, max_pages);
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if (npages == 0)
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goto unlock_free;
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sg_init_table(ctx->sgl.sgl, npages);
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ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);
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err = extract_iter_to_sg(&msg->msg_iter, LONG_MAX,
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&ctx->sgl.sgt, npages, 0);
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if (err < 0)
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goto unlock_free;
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len = err;
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sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);
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if (!msg_data_left(msg)) {
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err = hash_alloc_result(sk, ctx);
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if (err)
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goto unlock_free;
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}
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ahash_request_set_crypt(&ctx->req, ctx->sgl.sgt.sgl,
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ctx->result, len);
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if (!msg_data_left(msg) && !continuing &&
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!(msg->msg_flags & MSG_MORE)) {
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err = crypto_ahash_digest(&ctx->req);
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} else {
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if (need_init) {
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err = crypto_wait_req(
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crypto_ahash_init(&ctx->req),
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&ctx->wait);
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if (err)
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goto unlock_free;
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need_init = false;
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}
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if (msg_data_left(msg) || (msg->msg_flags & MSG_MORE))
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err = crypto_ahash_update(&ctx->req);
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else
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err = crypto_ahash_finup(&ctx->req);
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continuing = true;
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}
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err = crypto_wait_req(err, &ctx->wait);
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if (err)
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goto unlock_free;
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copied += len;
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af_alg_free_sg(&ctx->sgl);
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}
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done_more:
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ctx->more = msg->msg_flags & MSG_MORE;
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done:
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err = 0;
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unlock:
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release_sock(sk);
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return copied ?: err;
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unlock_free:
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af_alg_free_sg(&ctx->sgl);
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hash_free_result(sk, ctx);
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ctx->more = false;
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goto unlock;
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}
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static int hash_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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int flags)
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{
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struct sock *sk = sock->sk;
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struct alg_sock *ask = alg_sk(sk);
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struct hash_ctx *ctx = ask->private;
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unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
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bool result;
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int err;
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if (len > ds)
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len = ds;
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else if (len < ds)
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msg->msg_flags |= MSG_TRUNC;
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lock_sock(sk);
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result = ctx->result;
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err = hash_alloc_result(sk, ctx);
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if (err)
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goto unlock;
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ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);
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if (!result && !ctx->more) {
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err = crypto_wait_req(crypto_ahash_init(&ctx->req),
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&ctx->wait);
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if (err)
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goto unlock;
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}
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if (!result || ctx->more) {
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ctx->more = false;
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err = crypto_wait_req(crypto_ahash_final(&ctx->req),
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&ctx->wait);
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if (err)
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goto unlock;
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}
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err = memcpy_to_msg(msg, ctx->result, len);
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unlock:
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hash_free_result(sk, ctx);
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release_sock(sk);
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return err ?: len;
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}
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static int hash_accept(struct socket *sock, struct socket *newsock, int flags,
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bool kern)
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{
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struct sock *sk = sock->sk;
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struct alg_sock *ask = alg_sk(sk);
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struct hash_ctx *ctx = ask->private;
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struct ahash_request *req = &ctx->req;
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struct crypto_ahash *tfm;
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struct sock *sk2;
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struct alg_sock *ask2;
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struct hash_ctx *ctx2;
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char *state;
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bool more;
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int err;
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tfm = crypto_ahash_reqtfm(req);
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state = kmalloc(crypto_ahash_statesize(tfm), GFP_KERNEL);
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err = -ENOMEM;
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if (!state)
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goto out;
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lock_sock(sk);
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more = ctx->more;
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err = more ? crypto_ahash_export(req, state) : 0;
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release_sock(sk);
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if (err)
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goto out_free_state;
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err = af_alg_accept(ask->parent, newsock, kern);
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if (err)
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goto out_free_state;
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sk2 = newsock->sk;
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ask2 = alg_sk(sk2);
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ctx2 = ask2->private;
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ctx2->more = more;
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if (!more)
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goto out_free_state;
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err = crypto_ahash_import(&ctx2->req, state);
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if (err) {
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sock_orphan(sk2);
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sock_put(sk2);
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}
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out_free_state:
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kfree_sensitive(state);
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out:
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return err;
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}
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static struct proto_ops algif_hash_ops = {
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.family = PF_ALG,
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.connect = sock_no_connect,
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.socketpair = sock_no_socketpair,
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.getname = sock_no_getname,
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.ioctl = sock_no_ioctl,
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.listen = sock_no_listen,
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.shutdown = sock_no_shutdown,
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.mmap = sock_no_mmap,
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.bind = sock_no_bind,
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.release = af_alg_release,
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.sendmsg = hash_sendmsg,
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.recvmsg = hash_recvmsg,
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.accept = hash_accept,
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};
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static int hash_check_key(struct socket *sock)
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{
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int err = 0;
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struct sock *psk;
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struct alg_sock *pask;
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struct crypto_ahash *tfm;
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struct sock *sk = sock->sk;
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struct alg_sock *ask = alg_sk(sk);
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lock_sock(sk);
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if (!atomic_read(&ask->nokey_refcnt))
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goto unlock_child;
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psk = ask->parent;
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pask = alg_sk(ask->parent);
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tfm = pask->private;
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err = -ENOKEY;
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lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
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if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
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goto unlock;
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atomic_dec(&pask->nokey_refcnt);
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atomic_set(&ask->nokey_refcnt, 0);
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err = 0;
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unlock:
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release_sock(psk);
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unlock_child:
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release_sock(sk);
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return err;
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}
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static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
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size_t size)
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{
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int err;
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err = hash_check_key(sock);
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if (err)
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return err;
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return hash_sendmsg(sock, msg, size);
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}
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static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
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size_t ignored, int flags)
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{
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int err;
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err = hash_check_key(sock);
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if (err)
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return err;
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return hash_recvmsg(sock, msg, ignored, flags);
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}
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static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
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int flags, bool kern)
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{
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int err;
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err = hash_check_key(sock);
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if (err)
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return err;
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return hash_accept(sock, newsock, flags, kern);
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}
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static struct proto_ops algif_hash_ops_nokey = {
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.family = PF_ALG,
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.connect = sock_no_connect,
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.socketpair = sock_no_socketpair,
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.getname = sock_no_getname,
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.ioctl = sock_no_ioctl,
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.listen = sock_no_listen,
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.shutdown = sock_no_shutdown,
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.mmap = sock_no_mmap,
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.bind = sock_no_bind,
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.release = af_alg_release,
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.sendmsg = hash_sendmsg_nokey,
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.recvmsg = hash_recvmsg_nokey,
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.accept = hash_accept_nokey,
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};
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static void *hash_bind(const char *name, u32 type, u32 mask)
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{
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return crypto_alloc_ahash(name, type, mask);
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}
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static void hash_release(void *private)
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{
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crypto_free_ahash(private);
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}
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static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
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{
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return crypto_ahash_setkey(private, key, keylen);
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}
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static void hash_sock_destruct(struct sock *sk)
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{
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struct alg_sock *ask = alg_sk(sk);
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struct hash_ctx *ctx = ask->private;
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hash_free_result(sk, ctx);
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sock_kfree_s(sk, ctx, ctx->len);
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af_alg_release_parent(sk);
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}
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static int hash_accept_parent_nokey(void *private, struct sock *sk)
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{
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struct crypto_ahash *tfm = private;
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struct alg_sock *ask = alg_sk(sk);
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struct hash_ctx *ctx;
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unsigned int len = sizeof(*ctx) + crypto_ahash_reqsize(tfm);
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ctx = sock_kmalloc(sk, len, GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->result = NULL;
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ctx->len = len;
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ctx->more = false;
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crypto_init_wait(&ctx->wait);
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ask->private = ctx;
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ahash_request_set_tfm(&ctx->req, tfm);
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ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
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crypto_req_done, &ctx->wait);
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sk->sk_destruct = hash_sock_destruct;
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return 0;
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}
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static int hash_accept_parent(void *private, struct sock *sk)
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{
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struct crypto_ahash *tfm = private;
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if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
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return -ENOKEY;
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return hash_accept_parent_nokey(private, sk);
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}
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static const struct af_alg_type algif_type_hash = {
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.bind = hash_bind,
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.release = hash_release,
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.setkey = hash_setkey,
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.accept = hash_accept_parent,
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.accept_nokey = hash_accept_parent_nokey,
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.ops = &algif_hash_ops,
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.ops_nokey = &algif_hash_ops_nokey,
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.name = "hash",
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.owner = THIS_MODULE
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};
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static int __init algif_hash_init(void)
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{
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return af_alg_register_type(&algif_type_hash);
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}
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static void __exit algif_hash_exit(void)
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{
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int err = af_alg_unregister_type(&algif_type_hash);
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BUG_ON(err);
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}
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module_init(algif_hash_init);
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module_exit(algif_hash_exit);
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MODULE_LICENSE("GPL");
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