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![David Howells](/assets/img/avatar_default.png)
Lockdep issues a circular dependency warning when AFS issues an operation through AF_RXRPC from a context in which the VFS/VM holds the mmap_sem. The theory lockdep comes up with is as follows: (1) If the pagefault handler decides it needs to read pages from AFS, it calls AFS with mmap_sem held and AFS begins an AF_RXRPC call, but creating a call requires the socket lock: mmap_sem must be taken before sk_lock-AF_RXRPC (2) afs_open_socket() opens an AF_RXRPC socket and binds it. rxrpc_bind() binds the underlying UDP socket whilst holding its socket lock. inet_bind() takes its own socket lock: sk_lock-AF_RXRPC must be taken before sk_lock-AF_INET (3) Reading from a TCP socket into a userspace buffer might cause a fault and thus cause the kernel to take the mmap_sem, but the TCP socket is locked whilst doing this: sk_lock-AF_INET must be taken before mmap_sem However, lockdep's theory is wrong in this instance because it deals only with lock classes and not individual locks. The AF_INET lock in (2) isn't really equivalent to the AF_INET lock in (3) as the former deals with a socket entirely internal to the kernel that never sees userspace. This is a limitation in the design of lockdep. Fix the general case by: (1) Double up all the locking keys used in sockets so that one set are used if the socket is created by userspace and the other set is used if the socket is created by the kernel. (2) Store the kern parameter passed to sk_alloc() in a variable in the sock struct (sk_kern_sock). This informs sock_lock_init(), sock_init_data() and sk_clone_lock() as to the lock keys to be used. Note that the child created by sk_clone_lock() inherits the parent's kern setting. (3) Add a 'kern' parameter to ->accept() that is analogous to the one passed in to ->create() that distinguishes whether kernel_accept() or sys_accept4() was the caller and can be passed to sk_alloc(). Note that a lot of accept functions merely dequeue an already allocated socket. I haven't touched these as the new socket already exists before we get the parameter. Note also that there are a couple of places where I've made the accepted socket unconditionally kernel-based: irda_accept() rds_rcp_accept_one() tcp_accept_from_sock() because they follow a sock_create_kern() and accept off of that. Whilst creating this, I noticed that lustre and ocfs don't create sockets through sock_create_kern() and thus they aren't marked as for-kernel, though they appear to be internal. I wonder if these should do that so that they use the new set of lock keys. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
527 lines
10 KiB
C
527 lines
10 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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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 af_alg_completion completion;
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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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struct algif_hash_tfm {
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struct crypto_ahash *hash;
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bool has_key;
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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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int limit = ALG_MAX_PAGES * PAGE_SIZE;
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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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long copied = 0;
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int err;
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if (limit > sk->sk_sndbuf)
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limit = sk->sk_sndbuf;
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lock_sock(sk);
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if (!ctx->more) {
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if ((msg->msg_flags & MSG_MORE))
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hash_free_result(sk, ctx);
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err = af_alg_wait_for_completion(crypto_ahash_init(&ctx->req),
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&ctx->completion);
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if (err)
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goto unlock;
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}
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ctx->more = 0;
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while (msg_data_left(msg)) {
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int len = msg_data_left(msg);
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if (len > limit)
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len = limit;
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len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len);
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if (len < 0) {
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err = copied ? 0 : len;
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goto unlock;
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}
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ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
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err = af_alg_wait_for_completion(crypto_ahash_update(&ctx->req),
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&ctx->completion);
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af_alg_free_sg(&ctx->sgl);
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if (err)
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goto unlock;
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copied += len;
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iov_iter_advance(&msg->msg_iter, len);
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}
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err = 0;
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ctx->more = msg->msg_flags & MSG_MORE;
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if (!ctx->more) {
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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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err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
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&ctx->completion);
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}
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unlock:
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release_sock(sk);
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return err ?: copied;
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}
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static ssize_t hash_sendpage(struct socket *sock, struct page *page,
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int offset, size_t size, 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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int err;
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if (flags & MSG_SENDPAGE_NOTLAST)
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flags |= MSG_MORE;
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lock_sock(sk);
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sg_init_table(ctx->sgl.sg, 1);
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sg_set_page(ctx->sgl.sg, page, size, offset);
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if (!(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;
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} else if (!ctx->more)
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hash_free_result(sk, ctx);
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ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, ctx->result, size);
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if (!(flags & MSG_MORE)) {
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if (ctx->more)
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err = crypto_ahash_finup(&ctx->req);
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else
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err = crypto_ahash_digest(&ctx->req);
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} else {
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if (!ctx->more) {
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err = crypto_ahash_init(&ctx->req);
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err = af_alg_wait_for_completion(err, &ctx->completion);
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if (err)
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goto unlock;
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}
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err = crypto_ahash_update(&ctx->req);
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}
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err = af_alg_wait_for_completion(err, &ctx->completion);
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if (err)
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goto unlock;
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ctx->more = flags & MSG_MORE;
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unlock:
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release_sock(sk);
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return err ?: size;
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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 = af_alg_wait_for_completion(
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crypto_ahash_init(&ctx->req),
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&ctx->completion);
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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 = 0;
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err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
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&ctx->completion);
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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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char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req)) ? : 1];
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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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bool more;
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int err;
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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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return err;
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err = af_alg_accept(ask->parent, newsock, kern);
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if (err)
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return err;
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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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return err;
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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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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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.getsockopt = sock_no_getsockopt,
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.mmap = sock_no_mmap,
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.bind = sock_no_bind,
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.setsockopt = sock_no_setsockopt,
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.poll = sock_no_poll,
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.release = af_alg_release,
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.sendmsg = hash_sendmsg,
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.sendpage = hash_sendpage,
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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 algif_hash_tfm *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 (ask->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 (!tfm->has_key)
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goto unlock;
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if (!pask->refcnt++)
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sock_hold(psk);
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ask->refcnt = 1;
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sock_put(psk);
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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 ssize_t hash_sendpage_nokey(struct socket *sock, struct page *page,
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int offset, size_t size, 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_sendpage(sock, page, offset, size, flags);
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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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.getsockopt = sock_no_getsockopt,
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.mmap = sock_no_mmap,
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.bind = sock_no_bind,
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.setsockopt = sock_no_setsockopt,
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.poll = sock_no_poll,
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.release = af_alg_release,
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.sendmsg = hash_sendmsg_nokey,
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.sendpage = hash_sendpage_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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struct algif_hash_tfm *tfm;
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struct crypto_ahash *hash;
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tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
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if (!tfm)
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return ERR_PTR(-ENOMEM);
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hash = crypto_alloc_ahash(name, type, mask);
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if (IS_ERR(hash)) {
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kfree(tfm);
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return ERR_CAST(hash);
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}
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tfm->hash = hash;
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return tfm;
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}
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static void hash_release(void *private)
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{
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struct algif_hash_tfm *tfm = private;
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crypto_free_ahash(tfm->hash);
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kfree(tfm);
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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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struct algif_hash_tfm *tfm = private;
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int err;
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err = crypto_ahash_setkey(tfm->hash, key, keylen);
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tfm->has_key = !err;
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return err;
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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 hash_ctx *ctx;
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struct alg_sock *ask = alg_sk(sk);
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struct algif_hash_tfm *tfm = private;
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struct crypto_ahash *hash = tfm->hash;
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unsigned len = sizeof(*ctx) + crypto_ahash_reqsize(hash);
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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 = 0;
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af_alg_init_completion(&ctx->completion);
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ask->private = ctx;
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ahash_request_set_tfm(&ctx->req, hash);
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ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
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af_alg_complete, &ctx->completion);
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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 algif_hash_tfm *tfm = private;
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if (!tfm->has_key && crypto_ahash_has_setkey(tfm->hash))
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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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