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linux-next/crypto/algif_hash.c
Kees Cook b68a7ec1e9 crypto: hash - Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this
removes the VLAs in SHASH_DESC_ON_STACK (via crypto_shash_descsize())
by using the maximum allowable size (which is now more clearly captured
in a macro), along with a few other cases. Similar limits are turned into
macros as well.

A review of existing sizes shows that SHA512_DIGEST_SIZE (64) is the
largest digest size and that sizeof(struct sha3_state) (360) is the
largest descriptor size. The corresponding maximums are reduced.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-09-04 11:35:03 +08:00

494 lines
9.8 KiB
C

/*
* algif_hash: User-space interface for hash algorithms
*
* This file provides the user-space API for hash 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 <crypto/hash.h>
#include <crypto/if_alg.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/net.h>
#include <net/sock.h>
struct hash_ctx {
struct af_alg_sgl sgl;
u8 *result;
struct crypto_wait wait;
unsigned int len;
bool more;
struct ahash_request req;
};
static int hash_alloc_result(struct sock *sk, struct hash_ctx *ctx)
{
unsigned ds;
if (ctx->result)
return 0;
ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
if (!ctx->result)
return -ENOMEM;
memset(ctx->result, 0, ds);
return 0;
}
static void hash_free_result(struct sock *sk, struct hash_ctx *ctx)
{
unsigned ds;
if (!ctx->result)
return;
ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
sock_kzfree_s(sk, ctx->result, ds);
ctx->result = NULL;
}
static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
size_t ignored)
{
int limit = ALG_MAX_PAGES * PAGE_SIZE;
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
long copied = 0;
int err;
if (limit > sk->sk_sndbuf)
limit = sk->sk_sndbuf;
lock_sock(sk);
if (!ctx->more) {
if ((msg->msg_flags & MSG_MORE))
hash_free_result(sk, ctx);
err = crypto_wait_req(crypto_ahash_init(&ctx->req), &ctx->wait);
if (err)
goto unlock;
}
ctx->more = 0;
while (msg_data_left(msg)) {
int len = msg_data_left(msg);
if (len > limit)
len = limit;
len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len);
if (len < 0) {
err = copied ? 0 : len;
goto unlock;
}
ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
err = crypto_wait_req(crypto_ahash_update(&ctx->req),
&ctx->wait);
af_alg_free_sg(&ctx->sgl);
if (err)
goto unlock;
copied += len;
iov_iter_advance(&msg->msg_iter, len);
}
err = 0;
ctx->more = msg->msg_flags & MSG_MORE;
if (!ctx->more) {
err = hash_alloc_result(sk, ctx);
if (err)
goto unlock;
ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);
err = crypto_wait_req(crypto_ahash_final(&ctx->req),
&ctx->wait);
}
unlock:
release_sock(sk);
return err ?: copied;
}
static ssize_t hash_sendpage(struct socket *sock, struct page *page,
int offset, size_t size, int flags)
{
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
int err;
if (flags & MSG_SENDPAGE_NOTLAST)
flags |= MSG_MORE;
lock_sock(sk);
sg_init_table(ctx->sgl.sg, 1);
sg_set_page(ctx->sgl.sg, page, size, offset);
if (!(flags & MSG_MORE)) {
err = hash_alloc_result(sk, ctx);
if (err)
goto unlock;
} else if (!ctx->more)
hash_free_result(sk, ctx);
ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, ctx->result, size);
if (!(flags & MSG_MORE)) {
if (ctx->more)
err = crypto_ahash_finup(&ctx->req);
else
err = crypto_ahash_digest(&ctx->req);
} else {
if (!ctx->more) {
err = crypto_ahash_init(&ctx->req);
err = crypto_wait_req(err, &ctx->wait);
if (err)
goto unlock;
}
err = crypto_ahash_update(&ctx->req);
}
err = crypto_wait_req(err, &ctx->wait);
if (err)
goto unlock;
ctx->more = flags & MSG_MORE;
unlock:
release_sock(sk);
return err ?: size;
}
static int hash_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
{
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
bool result;
int err;
if (len > ds)
len = ds;
else if (len < ds)
msg->msg_flags |= MSG_TRUNC;
lock_sock(sk);
result = ctx->result;
err = hash_alloc_result(sk, ctx);
if (err)
goto unlock;
ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);
if (!result && !ctx->more) {
err = crypto_wait_req(crypto_ahash_init(&ctx->req),
&ctx->wait);
if (err)
goto unlock;
}
if (!result || ctx->more) {
ctx->more = 0;
err = crypto_wait_req(crypto_ahash_final(&ctx->req),
&ctx->wait);
if (err)
goto unlock;
}
err = memcpy_to_msg(msg, ctx->result, len);
unlock:
hash_free_result(sk, ctx);
release_sock(sk);
return err ?: len;
}
static int hash_accept(struct socket *sock, struct socket *newsock, int flags,
bool kern)
{
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
struct ahash_request *req = &ctx->req;
char state[HASH_MAX_STATESIZE];
struct sock *sk2;
struct alg_sock *ask2;
struct hash_ctx *ctx2;
bool more;
int err;
lock_sock(sk);
more = ctx->more;
err = more ? crypto_ahash_export(req, state) : 0;
release_sock(sk);
if (err)
return err;
err = af_alg_accept(ask->parent, newsock, kern);
if (err)
return err;
sk2 = newsock->sk;
ask2 = alg_sk(sk2);
ctx2 = ask2->private;
ctx2->more = more;
if (!more)
return err;
err = crypto_ahash_import(&ctx2->req, state);
if (err) {
sock_orphan(sk2);
sock_put(sk2);
}
return err;
}
static struct proto_ops algif_hash_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,
.getsockopt = sock_no_getsockopt,
.mmap = sock_no_mmap,
.bind = sock_no_bind,
.setsockopt = sock_no_setsockopt,
.release = af_alg_release,
.sendmsg = hash_sendmsg,
.sendpage = hash_sendpage,
.recvmsg = hash_recvmsg,
.accept = hash_accept,
};
static int hash_check_key(struct socket *sock)
{
int err = 0;
struct sock *psk;
struct alg_sock *pask;
struct crypto_ahash *tfm;
struct sock *sk = sock->sk;
struct alg_sock *ask = alg_sk(sk);
lock_sock(sk);
if (ask->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_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
goto unlock;
if (!pask->refcnt++)
sock_hold(psk);
ask->refcnt = 1;
sock_put(psk);
err = 0;
unlock:
release_sock(psk);
unlock_child:
release_sock(sk);
return err;
}
static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
size_t size)
{
int err;
err = hash_check_key(sock);
if (err)
return err;
return hash_sendmsg(sock, msg, size);
}
static ssize_t hash_sendpage_nokey(struct socket *sock, struct page *page,
int offset, size_t size, int flags)
{
int err;
err = hash_check_key(sock);
if (err)
return err;
return hash_sendpage(sock, page, offset, size, flags);
}
static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
size_t ignored, int flags)
{
int err;
err = hash_check_key(sock);
if (err)
return err;
return hash_recvmsg(sock, msg, ignored, flags);
}
static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
int flags, bool kern)
{
int err;
err = hash_check_key(sock);
if (err)
return err;
return hash_accept(sock, newsock, flags, kern);
}
static struct proto_ops algif_hash_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,
.getsockopt = sock_no_getsockopt,
.mmap = sock_no_mmap,
.bind = sock_no_bind,
.setsockopt = sock_no_setsockopt,
.release = af_alg_release,
.sendmsg = hash_sendmsg_nokey,
.sendpage = hash_sendpage_nokey,
.recvmsg = hash_recvmsg_nokey,
.accept = hash_accept_nokey,
};
static void *hash_bind(const char *name, u32 type, u32 mask)
{
return crypto_alloc_ahash(name, type, mask);
}
static void hash_release(void *private)
{
crypto_free_ahash(private);
}
static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
{
return crypto_ahash_setkey(private, key, keylen);
}
static void hash_sock_destruct(struct sock *sk)
{
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
hash_free_result(sk, ctx);
sock_kfree_s(sk, ctx, ctx->len);
af_alg_release_parent(sk);
}
static int hash_accept_parent_nokey(void *private, struct sock *sk)
{
struct crypto_ahash *tfm = private;
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx;
unsigned int len = sizeof(*ctx) + crypto_ahash_reqsize(tfm);
ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->result = NULL;
ctx->len = len;
ctx->more = 0;
crypto_init_wait(&ctx->wait);
ask->private = ctx;
ahash_request_set_tfm(&ctx->req, tfm);
ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &ctx->wait);
sk->sk_destruct = hash_sock_destruct;
return 0;
}
static int hash_accept_parent(void *private, struct sock *sk)
{
struct crypto_ahash *tfm = private;
if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
return -ENOKEY;
return hash_accept_parent_nokey(private, sk);
}
static const struct af_alg_type algif_type_hash = {
.bind = hash_bind,
.release = hash_release,
.setkey = hash_setkey,
.accept = hash_accept_parent,
.accept_nokey = hash_accept_parent_nokey,
.ops = &algif_hash_ops,
.ops_nokey = &algif_hash_ops_nokey,
.name = "hash",
.owner = THIS_MODULE
};
static int __init algif_hash_init(void)
{
return af_alg_register_type(&algif_type_hash);
}
static void __exit algif_hash_exit(void)
{
int err = af_alg_unregister_type(&algif_type_hash);
BUG_ON(err);
}
module_init(algif_hash_init);
module_exit(algif_hash_exit);
MODULE_LICENSE("GPL");