diff options
Diffstat (limited to 'crypto/algif_akcipher.c')
| -rw-r--r-- | crypto/algif_akcipher.c | 468 |
1 files changed, 468 insertions, 0 deletions
diff --git a/crypto/algif_akcipher.c b/crypto/algif_akcipher.c new file mode 100644 index 000000000000..a9fb618458ce --- /dev/null +++ b/crypto/algif_akcipher.c @@ -0,0 +1,468 @@ +/* + * algif_akcipher: User-space interface for asymmetric cipher algorithms + * + * Copyright (C) 2018 - 2020, Stephan Mueller <smueller@chronox.de> + * + * This file provides the user-space API for asymmetric ciphers. + * + * 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. + * + * The following concept of the memory management is used: + * + * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is + * filled by user space with the data submitted via sendpage/sendmsg. Filling + * up the TX SGL does not cause a crypto operation -- the data will only be + * tracked by the kernel. Upon receipt of one recvmsg call, the caller must + * provide a buffer which is tracked with the RX SGL. + * + * During the processing of the recvmsg operation, the cipher request is + * allocated and prepared. As part of the recvmsg operation, the processed + * TX buffers are extracted from the TX SGL into a separate SGL. + * + * After the completion of the crypto operation, the RX SGL and the cipher + * request is released. The extracted TX SGL parts are released together with + * the RX SGL release. + */ + +#include <crypto/akcipher.h> +#include <crypto/if_alg.h> +#include <crypto/scatterwalk.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/net.h> +#include <net/sock.h> + +struct akcipher_tfm { + struct crypto_akcipher *akcipher; + bool has_key; +}; + +static int akcipher_sendmsg(struct socket *sock, struct msghdr *msg, + size_t size) +{ + return af_alg_sendmsg(sock, msg, size, 0); +} + +static inline int akcipher_cipher_op(struct af_alg_ctx *ctx, + struct af_alg_async_req *areq) +{ + switch (ctx->op) { + case ALG_OP_ENCRYPT: + return crypto_akcipher_encrypt(&areq->cra_u.akcipher_req); + case ALG_OP_DECRYPT: + return crypto_akcipher_decrypt(&areq->cra_u.akcipher_req); + case ALG_OP_SIGN: + return crypto_akcipher_sign(&areq->cra_u.akcipher_req); + case ALG_OP_VERIFY: + return crypto_akcipher_verify(&areq->cra_u.akcipher_req); + default: + return -EOPNOTSUPP; + } +} + +static int _akcipher_recvmsg(struct socket *sock, struct msghdr *msg, + size_t ignored, int flags) +{ + struct sock *sk = sock->sk; + struct alg_sock *ask = alg_sk(sk); + struct sock *psk = ask->parent; + struct alg_sock *pask = alg_sk(psk); + struct af_alg_ctx *ctx = ask->private; + struct akcipher_tfm *akc = pask->private; + struct crypto_akcipher *tfm = akc->akcipher; + struct af_alg_async_req *areq; + size_t len; + size_t used; + int err; + int maxsize; + + if (!ctx->used) { + err = af_alg_wait_for_data(sk, flags, 0); + if (err) + return err; + } + + maxsize = crypto_akcipher_maxsize(tfm); + if (maxsize < 0) + return maxsize; + + /* Allocate cipher request for current operation. */ + areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + + crypto_akcipher_reqsize(tfm)); + if (IS_ERR(areq)) + return PTR_ERR(areq); + + /* convert iovecs of output buffers into RX SGL */ + err = af_alg_get_rsgl(sk, msg, flags, areq, maxsize, &len); + if (err) + goto free; + + /* ensure output buffer is sufficiently large */ + if (len < maxsize) { + err = -EMSGSIZE; + goto free; + } + + /* + * Create a per request TX SGL for this request which tracks the + * SG entries from the global TX SGL. + */ + used = ctx->used; + areq->tsgl_entries = af_alg_count_tsgl(sk, used, 0); + if (!areq->tsgl_entries) + areq->tsgl_entries = 1; + areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) * areq->tsgl_entries, + GFP_KERNEL); + if (!areq->tsgl) { + err = -ENOMEM; + goto free; + } + sg_init_table(areq->tsgl, areq->tsgl_entries); + af_alg_pull_tsgl(sk, used, areq->tsgl, 0); + + /* Initialize the crypto operation */ + akcipher_request_set_tfm(&areq->cra_u.akcipher_req, tfm); + akcipher_request_set_crypt(&areq->cra_u.akcipher_req, areq->tsgl, + areq->first_rsgl.sgl.sg, used, len); + + if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { + /* AIO operation */ + sock_hold(sk); + areq->iocb = msg->msg_iocb; + + /* Remember output size that will be generated. */ + areq->outlen = areq->cra_u.akcipher_req.dst_len ? + areq->cra_u.akcipher_req.dst_len : len; + + akcipher_request_set_callback(&areq->cra_u.akcipher_req, + CRYPTO_TFM_REQ_MAY_SLEEP, + af_alg_async_cb, areq); + err = akcipher_cipher_op(ctx, areq); + + /* AIO operation in progress */ + if (err == -EINPROGRESS || err == -EBUSY) + return -EIOCBQUEUED; + + sock_put(sk); + } else { + /* Synchronous operation */ + akcipher_request_set_callback(&areq->cra_u.akcipher_req, + CRYPTO_TFM_REQ_MAY_SLEEP | + CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, + &ctx->wait); + err = crypto_wait_req(akcipher_cipher_op(ctx, areq), + &ctx->wait); + } + +free: + af_alg_free_resources(areq); + + return err ? err : areq->cra_u.akcipher_req.dst_len; +} + +static int akcipher_recvmsg(struct socket *sock, struct msghdr *msg, + size_t ignored, int flags) +{ + struct sock *sk = sock->sk; + struct alg_sock *ask = alg_sk(sk); + struct sock *psk = ask->parent; + struct alg_sock *pask = alg_sk(psk); + struct akcipher_tfm *akc = pask->private; + struct crypto_akcipher *tfm = akc->akcipher; + int ret = 0; + int err; + + lock_sock(sk); + + while (msg_data_left(msg)) { + err = _akcipher_recvmsg(sock, msg, ignored, flags); + + /* + * This error covers -EIOCBQUEUED which implies that we can + * only handle one AIO request. If the caller wants to have + * multiple AIO requests in parallel, he must make multiple + * separate AIO calls. + */ + if (err <= 0) { + if (err == -EIOCBQUEUED || err == -EBADMSG || !ret) + ret = err; + goto out; + } + + ret += err; + + /* + * The caller must provide crypto_akcipher_maxsize per request. + * If he provides more, we conclude that multiple akcipher + * operations are requested. + */ + iov_iter_advance(&msg->msg_iter, + crypto_akcipher_maxsize(tfm) - err); + } + +out: + af_alg_wmem_wakeup(sk); + release_sock(sk); + return ret; +} + +static struct proto_ops algif_akcipher_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, + .mmap = sock_no_mmap, + .bind = sock_no_bind, + .accept = sock_no_accept, + + .release = af_alg_release, + .sendmsg = akcipher_sendmsg, + .sendpage = af_alg_sendpage, + .recvmsg = akcipher_recvmsg, + .poll = af_alg_poll, +}; + +static int akcipher_check_key(struct socket *sock) +{ + struct sock *psk; + struct alg_sock *pask; + struct akcipher_tfm *tfm; + struct sock *sk = sock->sk; + struct alg_sock *ask = alg_sk(sk); + int err = 0; + + lock_sock(sk); + if (!atomic_read(&ask->nokey_refcnt)) + goto unlock_child; + + psk = ask->parent; + pask = alg_sk(ask->parent); + tfm = pask->private; + + lock_sock_nested(psk, SINGLE_DEPTH_NESTING); + if (!tfm->has_key) { + err = -ENOKEY; + goto unlock; + } + + atomic_dec(&pask->nokey_refcnt); + atomic_set(&ask->nokey_refcnt, 0); + + 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 af_alg_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, + .mmap = sock_no_mmap, + .bind = sock_no_bind, + .accept = sock_no_accept, + + .release = af_alg_release, + .sendmsg = akcipher_sendmsg_nokey, + .sendpage = akcipher_sendpage_nokey, + .recvmsg = akcipher_recvmsg_nokey, + .poll = af_alg_poll, +}; + +static void *akcipher_bind(const char *name, u32 type, u32 mask) +{ + struct akcipher_tfm *tfm; + struct crypto_akcipher *akcipher; + + tfm = kmalloc(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; + tfm->has_key = false; + + return tfm; +} + +static void akcipher_release(void *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) +{ + 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 the maximum size of the akcipher operation. */ + if (!err) + err = crypto_akcipher_maxsize(akcipher); + + return err; +} + +static int akcipher_setpubkey(void *private, const u8 *key, unsigned int 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 the maximum size of the akcipher operation. */ + if (!err) + err = crypto_akcipher_maxsize(akcipher); + + return err; +} + +static void akcipher_sock_destruct(struct sock *sk) +{ + struct alg_sock *ask = alg_sk(sk); + struct af_alg_ctx *ctx = ask->private; + + af_alg_pull_tsgl(sk, ctx->used, NULL, 0); + sock_kfree_s(sk, ctx, ctx->len); + af_alg_release_parent(sk); +} + +static int akcipher_accept_parent_nokey(void *private, struct sock *sk) +{ + struct af_alg_ctx *ctx; + struct alg_sock *ask = alg_sk(sk); + unsigned int len = sizeof(*ctx); + + ctx = sock_kmalloc(sk, len, GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + INIT_LIST_HEAD(&ctx->tsgl_list); + ctx->len = len; + ctx->used = 0; + atomic_set(&ctx->rcvused, 0); + ctx->more = 0; + ctx->merge = 0; + ctx->op = 0; + crypto_init_wait(&ctx->wait); + + ask->private = ctx; + + sk->sk_destruct = akcipher_sock_destruct; + + 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, + .setauthsize = NULL, + .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 +}; + +static int __init algif_akcipher_init(void) +{ + return af_alg_register_type(&algif_type_akcipher); +} + +static void __exit algif_akcipher_exit(void) +{ + int err = af_alg_unregister_type(&algif_type_akcipher); + + BUG_ON(err); +} + +module_init(algif_akcipher_init); +module_exit(algif_akcipher_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); +MODULE_DESCRIPTION("Asymmetric kernel crypto API user space interface"); + |