[PATCH v6 5/6] crypto: algif_akcipher - add ops_nokey

Tadeusz Struk
2016-05-15T04:18:19Z

Similar to algif_skcipher and algif_hash, algif_akcipher needs
to prevent user space from using the interface in an improper way.
This patch adds nokey ops handlers, which do just that.

Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
---
crypto/algif_akcipher.c | 159 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 152 insertions(+), 7 deletions(-)

diff --git a/crypto/algif_akcipher.c b/crypto/algif_akcipher.c
index 6342b6e..e00793d 100644
--- a/crypto/algif_akcipher.c
+++ b/crypto/algif_akcipher.c
@@ -27,6 +27,11 @@ struct akcipher_sg_list {
struct scatterlist sg[ALG_MAX_PAGES];
};

+struct akcipher_tfm {
+ struct crypto_akcipher *akcipher;
+ bool has_key;
+};
+
struct akcipher_ctx {
struct akcipher_sg_list tsgl;
struct af_alg_sgl rsgl[ALG_MAX_PAGES];
@@ -450,25 +455,151 @@ static struct proto_ops algif_akcipher_ops = {
.poll = akcipher_poll,
};

+static int akcipher_check_key(struct socket *sock)
+{
+ int err = 0;
+ struct sock *psk;
+ struct alg_sock *pask;
+ struct akcipher_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 akcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
+ size_t size)
+{
+ int err;
+
+ err = akcipher_check_key(sock);
+ if (err)
+ return err;
+
+ return akcipher_sendmsg(sock, msg, size);
+}
+
+static ssize_t akcipher_sendpage_nokey(struct socket *sock, struct page *page,
+ int offset, size_t size, int flags)
+{
+ int err;
+
+ err = akcipher_check_key(sock);
+ if (err)
+ return err;
+
+ return akcipher_sendpage(sock, page, offset, size, flags);
+}
+
+static int akcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
+ size_t ignored, int flags)
+{
+ int err;
+
+ err = akcipher_check_key(sock);
+ if (err)
+ return err;
+
+ return akcipher_recvmsg(sock, msg, ignored, flags);
+}
+
+static struct proto_ops algif_akcipher_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,
+ .accept = sock_no_accept,
+ .setsockopt = sock_no_setsockopt,
+
+ .release = af_alg_release,
+ .sendmsg = akcipher_sendmsg_nokey,
+ .sendpage = akcipher_sendpage_nokey,
+ .recvmsg = akcipher_recvmsg_nokey,
+ .poll = akcipher_poll,
+};
+
static void *akcipher_bind(const char *name, u32 type, u32 mask)
{
- return crypto_alloc_akcipher(name, type, mask);
+ struct akcipher_tfm *tfm;
+ struct crypto_akcipher *akcipher;
+
+ tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
+ if (!tfm)
+ return ERR_PTR(-ENOMEM);
+
+ akcipher = crypto_alloc_akcipher(name, type, mask);
+ if (IS_ERR(akcipher)) {
+ kfree(tfm);
+ return ERR_CAST(akcipher);
+ }
+
+ tfm->akcipher = akcipher;
+ return tfm;
}

static void akcipher_release(void *private)
{
- crypto_free_akcipher(private);
+ struct akcipher_tfm *tfm = private;
+ struct crypto_akcipher *akcipher = tfm->akcipher;
+
+ crypto_free_akcipher(akcipher);
+ kfree(tfm);
}

static int akcipher_setprivkey(void *private, const u8 *key,
unsigned int keylen)
{
- return crypto_akcipher_set_priv_key(private, key, keylen);
+ struct akcipher_tfm *tfm = private;
+ struct crypto_akcipher *akcipher = tfm->akcipher;
+ int err;
+
+ err = crypto_akcipher_set_priv_key(akcipher, key, keylen);
+ tfm->has_key = !err;
+ return err;
}

static int akcipher_setpubkey(void *private, const u8 *key, unsigned int keylen)
{
- return crypto_akcipher_set_pub_key(private, key, keylen);
+ struct akcipher_tfm *tfm = private;
+ struct crypto_akcipher *akcipher = tfm->akcipher;
+ int err;
+
+ err = crypto_akcipher_set_pub_key(akcipher, key, keylen);
+ tfm->has_key = !err;
+ return err;
}

static void akcipher_sock_destruct(struct sock *sk)
@@ -481,11 +612,13 @@ static void akcipher_sock_destruct(struct sock *sk)
af_alg_release_parent(sk);
}

-static int akcipher_accept_parent(void *private, struct sock *sk)
+static int akcipher_accept_parent_nokey(void *private, struct sock *sk)
{
struct akcipher_ctx *ctx;
struct alg_sock *ask = alg_sk(sk);
- unsigned int len = sizeof(*ctx) + crypto_akcipher_reqsize(private);
+ struct akcipher_tfm *tfm = private;
+ struct crypto_akcipher *akcipher = tfm->akcipher;
+ unsigned int len = sizeof(*ctx) + crypto_akcipher_reqsize(akcipher);

ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
@@ -503,7 +636,7 @@ static int akcipher_accept_parent(void *private, struct sock *sk)

ask->private = ctx;

- akcipher_request_set_tfm(&ctx->req, private);
+ akcipher_request_set_tfm(&ctx->req, akcipher);
akcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
af_alg_complete, &ctx->completion);

@@ -512,13 +645,25 @@ static int akcipher_accept_parent(void *private, struct sock *sk)
return 0;
}

+static int akcipher_accept_parent(void *private, struct sock *sk)
+{
+ struct akcipher_tfm *tfm = private;
+
+ if (!tfm->has_key)
+ return -ENOKEY;
+
+ return akcipher_accept_parent_nokey(private, sk);
+}
+
static const struct af_alg_type algif_type_akcipher = {
.bind = akcipher_bind,
.release = akcipher_release,
.setkey = akcipher_setprivkey,
.setpubkey = akcipher_setpubkey,
.accept = akcipher_accept_parent,
+ .accept_nokey = akcipher_accept_parent_nokey,
.ops = &algif_akcipher_ops,
+ .ops_nokey = &algif_akcipher_ops_nokey,
.name = "akcipher",
.owner = THIS_MODULE
};