/* * algif_skcipher: User-space interface for skcipher algorithms * * This file provides the user-space API for symmetric key ciphers. * * 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. * * 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/scatterwalk.h> #include <crypto/skcipher.h> #include <crypto/if_alg.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 skcipher_tfm { struct crypto_skcipher *skcipher; bool has_key; }; static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) { 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 skcipher_tfm *skc = pask->private; struct crypto_skcipher *tfm = skc->skcipher; unsigned ivsize = crypto_skcipher_ivsize(tfm); return af_alg_sendmsg(sock, msg, size, ivsize); } static int _skcipher_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 skcipher_tfm *skc = pask->private; struct crypto_skcipher *tfm = skc->skcipher; unsigned int bs = crypto_skcipher_blocksize(tfm); struct af_alg_async_req *areq; int err = 0; size_t len = 0; if (!ctx->used) { err = af_alg_wait_for_data(sk, flags); if (err) return err; } /* Allocate cipher request for current operation. */ areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + crypto_skcipher_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, -1, &len); if (err) goto free; /* Process only as much RX buffers for which we have TX data */ if (len > ctx->used) len = ctx->used; /* * If more buffers are to be expected to be processed, process only * full block size buffers. */ if (ctx->more || len < ctx->used) len -= len % bs; /* * Create a per request TX SGL for this request which tracks the * SG entries from the global TX SGL. */ areq->tsgl_entries = af_alg_count_tsgl(sk, len, 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, len, areq->tsgl, 0); /* Initialize the crypto operation */ skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm); skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl, areq->first_rsgl.sgl.sg, len, ctx->iv); 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 = len; skcipher_request_set_callback(&areq->cra_u.skcipher_req, CRYPTO_TFM_REQ_MAY_SLEEP, af_alg_async_cb, areq); err = ctx->enc ? crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : crypto_skcipher_decrypt(&areq->cra_u.skcipher_req); /* AIO operation in progress */ if (err == -EINPROGRESS || err == -EBUSY) return -EIOCBQUEUED; sock_put(sk); } else { /* Synchronous operation */ skcipher_request_set_callback(&areq->cra_u.skcipher_req, CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_complete, &ctx->completion); err = af_alg_wait_for_completion(ctx->enc ? crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : crypto_skcipher_decrypt(&areq->cra_u.skcipher_req), &ctx->completion); } free: af_alg_free_resources(areq); return err ? err : len; } static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored, int flags) { struct sock *sk = sock->sk; int ret = 0; lock_sock(sk); while (msg_data_left(msg)) { int err = _skcipher_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. * * Also return the error if no data has been processed so far. */ if (err <= 0) { if (err == -EIOCBQUEUED || !ret) ret = err; goto out; } ret += err; } out: af_alg_wmem_wakeup(sk); release_sock(sk); return ret; } static struct proto_ops algif_skcipher_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, .accept = sock_no_accept, .setsockopt = sock_no_setsockopt, .release = af_alg_release, .sendmsg = skcipher_sendmsg, .sendpage = af_alg_sendpage, .recvmsg = skcipher_recvmsg, .poll = af_alg_poll, }; static int skcipher_check_key(struct socket *sock) { int err = 0; struct sock *psk; struct alg_sock *pask; struct skcipher_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 skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg, size_t size) { int err; err = skcipher_check_key(sock); if (err) return err; return skcipher_sendmsg(sock, msg, size); } static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page, int offset, size_t size, int flags) { int err; err = skcipher_check_key(sock); if (err) return err; return af_alg_sendpage(sock, page, offset, size, flags); } static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg, size_t ignored, int flags) { int err; err = skcipher_check_key(sock); if (err) return err; return skcipher_recvmsg(sock, msg, ignored, flags); } static struct proto_ops algif_skcipher_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 = skcipher_sendmsg_nokey, .sendpage = skcipher_sendpage_nokey, .recvmsg = skcipher_recvmsg_nokey, .poll = af_alg_poll, }; static void *skcipher_bind(const char *name, u32 type, u32 mask) { struct skcipher_tfm *tfm; struct crypto_skcipher *skcipher; tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); if (!tfm) return ERR_PTR(-ENOMEM); skcipher = crypto_alloc_skcipher(name, type, mask); if (IS_ERR(skcipher)) { kfree(tfm); return ERR_CAST(skcipher); } tfm->skcipher = skcipher; return tfm; } static void skcipher_release(void *private) { struct skcipher_tfm *tfm = private; crypto_free_skcipher(tfm->skcipher); kfree(tfm); } static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) { struct skcipher_tfm *tfm = private; int err; err = crypto_skcipher_setkey(tfm->skcipher, key, keylen); tfm->has_key = !err; return err; } static void skcipher_sock_destruct(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct af_alg_ctx *ctx = ask->private; struct sock *psk = ask->parent; struct alg_sock *pask = alg_sk(psk); struct skcipher_tfm *skc = pask->private; struct crypto_skcipher *tfm = skc->skcipher; af_alg_pull_tsgl(sk, ctx->used, NULL, 0); sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm)); sock_kfree_s(sk, ctx, ctx->len); af_alg_release_parent(sk); } static int skcipher_accept_parent_nokey(void *private, struct sock *sk) { struct af_alg_ctx *ctx; struct alg_sock *ask = alg_sk(sk); struct skcipher_tfm *tfm = private; struct crypto_skcipher *skcipher = tfm->skcipher; unsigned int len = sizeof(*ctx); ctx = sock_kmalloc(sk, len, GFP_KERNEL); if (!ctx) return -ENOMEM; ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher), GFP_KERNEL); if (!ctx->iv) { sock_kfree_s(sk, ctx, len); return -ENOMEM; } memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher)); INIT_LIST_HEAD(&ctx->tsgl_list); ctx->len = len; ctx->used = 0; atomic_set(&ctx->rcvused, 0); ctx->more = 0; ctx->merge = 0; ctx->enc = 0; af_alg_init_completion(&ctx->completion); ask->private = ctx; sk->sk_destruct = skcipher_sock_destruct; return 0; } static int skcipher_accept_parent(void *private, struct sock *sk) { struct skcipher_tfm *tfm = private; if (!tfm->has_key && crypto_skcipher_has_setkey(tfm->skcipher)) return -ENOKEY; return skcipher_accept_parent_nokey(private, sk); } static const struct af_alg_type algif_type_skcipher = { .bind = skcipher_bind, .release = skcipher_release, .setkey = skcipher_setkey, .accept = skcipher_accept_parent, .accept_nokey = skcipher_accept_parent_nokey, .ops = &algif_skcipher_ops, .ops_nokey = &algif_skcipher_ops_nokey, .name = "skcipher", .owner = THIS_MODULE }; static int __init algif_skcipher_init(void) { return af_alg_register_type(&algif_type_skcipher); } static void __exit algif_skcipher_exit(void) { int err = af_alg_unregister_type(&algif_type_skcipher); BUG_ON(err); } module_init(algif_skcipher_init); module_exit(algif_skcipher_exit); MODULE_LICENSE("GPL");