linux_dsm_epyc7002/crypto/algif_hash.c
Jiri Slaby 6207119444 crypto: algif_hash - avoid zero-sized array
With this reproducer:
  struct sockaddr_alg alg = {
          .salg_family = 0x26,
          .salg_type = "hash",
          .salg_feat = 0xf,
          .salg_mask = 0x5,
          .salg_name = "digest_null",
  };
  int sock, sock2;

  sock = socket(AF_ALG, SOCK_SEQPACKET, 0);
  bind(sock, (struct sockaddr *)&alg, sizeof(alg));
  sock2 = accept(sock, NULL, NULL);
  setsockopt(sock, SOL_ALG, ALG_SET_KEY, "\x9b\xca", 2);
  accept(sock2, NULL, NULL);

==== 8< ======== 8< ======== 8< ======== 8< ====

one can immediatelly see an UBSAN warning:
UBSAN: Undefined behaviour in crypto/algif_hash.c:187:7
variable length array bound value 0 <= 0
CPU: 0 PID: 15949 Comm: syz-executor Tainted: G            E      4.4.30-0-default 
...
Call Trace:
...
 [<ffffffff81d598fd>] ? __ubsan_handle_vla_bound_not_positive+0x13d/0x188
 [<ffffffff81d597c0>] ? __ubsan_handle_out_of_bounds+0x1bc/0x1bc
 [<ffffffffa0e2204d>] ? hash_accept+0x5bd/0x7d0 [algif_hash]
 [<ffffffffa0e2293f>] ? hash_accept_nokey+0x3f/0x51 [algif_hash]
 [<ffffffffa0e206b0>] ? hash_accept_parent_nokey+0x4a0/0x4a0 [algif_hash]
 [<ffffffff8235c42b>] ? SyS_accept+0x2b/0x40

It is a correct warning, as hash state is propagated to accept as zero,
but creating a zero-length variable array is not allowed in C.

Fix this as proposed by Herbert -- do "?: 1" on that site. No sizeof or
similar happens in the code there, so we just allocate one byte even
though we do not use the array.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net> (maintainer:CRYPTO API)
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2016-12-27 17:50:52 +08:00

527 lines
10 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 af_alg_completion completion;
unsigned int len;
bool more;
struct ahash_request req;
};
struct algif_hash_tfm {
struct crypto_ahash *hash;
bool has_key;
};
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 = af_alg_wait_for_completion(crypto_ahash_init(&ctx->req),
&ctx->completion);
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 = af_alg_wait_for_completion(crypto_ahash_update(&ctx->req),
&ctx->completion);
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 = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
&ctx->completion);
}
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 = af_alg_wait_for_completion(err, &ctx->completion);
if (err)
goto unlock;
}
err = crypto_ahash_update(&ctx->req);
}
err = af_alg_wait_for_completion(err, &ctx->completion);
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 = af_alg_wait_for_completion(
crypto_ahash_init(&ctx->req),
&ctx->completion);
if (err)
goto unlock;
}
if (!result || ctx->more) {
ctx->more = 0;
err = af_alg_wait_for_completion(crypto_ahash_final(&ctx->req),
&ctx->completion);
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)
{
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[crypto_ahash_statesize(crypto_ahash_reqtfm(req)) ? : 1];
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);
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,
.poll = sock_no_poll,
.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 algif_hash_tfm *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 (!tfm->has_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)
{
int err;
err = hash_check_key(sock);
if (err)
return err;
return hash_accept(sock, newsock, flags);
}
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,
.poll = sock_no_poll,
.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)
{
struct algif_hash_tfm *tfm;
struct crypto_ahash *hash;
tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
if (!tfm)
return ERR_PTR(-ENOMEM);
hash = crypto_alloc_ahash(name, type, mask);
if (IS_ERR(hash)) {
kfree(tfm);
return ERR_CAST(hash);
}
tfm->hash = hash;
return tfm;
}
static void hash_release(void *private)
{
struct algif_hash_tfm *tfm = private;
crypto_free_ahash(tfm->hash);
kfree(tfm);
}
static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
{
struct algif_hash_tfm *tfm = private;
int err;
err = crypto_ahash_setkey(tfm->hash, key, keylen);
tfm->has_key = !err;
return err;
}
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 hash_ctx *ctx;
struct alg_sock *ask = alg_sk(sk);
struct algif_hash_tfm *tfm = private;
struct crypto_ahash *hash = tfm->hash;
unsigned len = sizeof(*ctx) + crypto_ahash_reqsize(hash);
ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->result = NULL;
ctx->len = len;
ctx->more = 0;
af_alg_init_completion(&ctx->completion);
ask->private = ctx;
ahash_request_set_tfm(&ctx->req, hash);
ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
af_alg_complete, &ctx->completion);
sk->sk_destruct = hash_sock_destruct;
return 0;
}
static int hash_accept_parent(void *private, struct sock *sk)
{
struct algif_hash_tfm *tfm = private;
if (!tfm->has_key && crypto_ahash_has_setkey(tfm->hash))
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");