// SPDX-License-Identifier: GPL-2.0-or-later /* * algif_aead: User-space interface for AEAD algorithms * * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de> * * This file provides the user-space API for AEAD ciphers. * * 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/internal/aead.h> #include <crypto/scatterwalk.h> #include <crypto/if_alg.h> #include <crypto/skcipher.h> #include <crypto/null.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 aead_tfm { struct crypto_aead *aead; struct crypto_sync_skcipher *null_tfm; }; static inline bool aead_sufficient_data(struct 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 aead_tfm *aeadc = pask->private; struct crypto_aead *tfm = aeadc->aead; unsigned int as = crypto_aead_authsize(tfm); /* * The minimum amount of memory needed for an AEAD cipher is * the AAD and in case of decryption the tag. */ return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as); } static int aead_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 aead_tfm *aeadc = pask->private; struct crypto_aead *tfm = aeadc->aead; unsigned int ivsize = crypto_aead_ivsize(tfm); return af_alg_sendmsg(sock, msg, size, ivsize); } static int crypto_aead_copy_sgl(struct crypto_sync_skcipher *null_tfm, struct scatterlist *src, struct scatterlist *dst, unsigned int len) { SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm); skcipher_request_set_sync_tfm(skreq, null_tfm); skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); skcipher_request_set_crypt(skreq, src, dst, len, NULL); return crypto_skcipher_encrypt(skreq); } static int _aead_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 aead_tfm *aeadc = pask->private; struct crypto_aead *tfm = aeadc->aead; struct crypto_sync_skcipher *null_tfm = aeadc->null_tfm; unsigned int i, as = crypto_aead_authsize(tfm); struct af_alg_async_req *areq; struct af_alg_tsgl *tsgl, *tmp; struct scatterlist *rsgl_src, *tsgl_src = NULL; int err = 0; size_t used = 0; /* [in] TX bufs to be en/decrypted */ size_t outlen = 0; /* [out] RX bufs produced by kernel */ size_t usedpages = 0; /* [in] RX bufs to be used from user */ size_t processed = 0; /* [in] TX bufs to be consumed */ if (!ctx->init || ctx->more) { err = af_alg_wait_for_data(sk, flags, 0); if (err) return err; } /* * Data length provided by caller via sendmsg/sendpage that has not * yet been processed. */ used = ctx->used; /* * Make sure sufficient data is present -- note, the same check is * also present in sendmsg/sendpage. The checks in sendpage/sendmsg * shall provide an information to the data sender that something is * wrong, but they are irrelevant to maintain the kernel integrity. * We need this check here too in case user space decides to not honor * the error message in sendmsg/sendpage and still call recvmsg. This * check here protects the kernel integrity. */ if (!aead_sufficient_data(sk)) return -EINVAL; /* * Calculate the minimum output buffer size holding the result of the * cipher operation. When encrypting data, the receiving buffer is * larger by the tag length compared to the input buffer as the * encryption operation generates the tag. For decryption, the input * buffer provides the tag which is consumed resulting in only the * plaintext without a buffer for the tag returned to the caller. */ if (ctx->enc) outlen = used + as; else outlen = used - as; /* * The cipher operation input data is reduced by the associated data * length as this data is processed separately later on. */ used -= ctx->aead_assoclen; /* Allocate cipher request for current operation. */ areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + crypto_aead_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, outlen, &usedpages); if (err) goto free; /* * Ensure output buffer is sufficiently large. If the caller provides * less buffer space, only use the relative required input size. This * allows AIO operation where the caller sent all data to be processed * and the AIO operation performs the operation on the different chunks * of the input data. */ if (usedpages < outlen) { size_t less = outlen - usedpages; if (used < less) { err = -EINVAL; goto free; } used -= less; outlen -= less; } processed = used + ctx->aead_assoclen; list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) { for (i = 0; i < tsgl->cur; i++) { struct scatterlist *process_sg = tsgl->sg + i; if (!(process_sg->length) || !sg_page(process_sg)) continue; tsgl_src = process_sg; break; } if (tsgl_src) break; } if (processed && !tsgl_src) { err = -EFAULT; goto free; } /* * Copy of AAD from source to destination * * The AAD is copied to the destination buffer without change. Even * when user space uses an in-place cipher operation, the kernel * will copy the data as it does not see whether such in-place operation * is initiated. * * To ensure efficiency, the following implementation ensure that the * ciphers are invoked to perform a crypto operation in-place. This * is achieved by memory management specified as follows. */ /* Use the RX SGL as source (and destination) for crypto op. */ rsgl_src = areq->first_rsgl.sgl.sg; if (ctx->enc) { /* * Encryption operation - The in-place cipher operation is * achieved by the following operation: * * TX SGL: AAD || PT * | | * | copy | * v v * RX SGL: AAD || PT || Tag */ err = crypto_aead_copy_sgl(null_tfm, tsgl_src, areq->first_rsgl.sgl.sg, processed); if (err) goto free; af_alg_pull_tsgl(sk, processed, NULL, 0); } else { /* * Decryption operation - To achieve an in-place cipher * operation, the following SGL structure is used: * * TX SGL: AAD || CT || Tag * | | ^ * | copy | | Create SGL link. * v v | * RX SGL: AAD || CT ----+ */ /* Copy AAD || CT to RX SGL buffer for in-place operation. */ err = crypto_aead_copy_sgl(null_tfm, tsgl_src, areq->first_rsgl.sgl.sg, outlen); if (err) goto free; /* Create TX SGL for tag and chain it to RX SGL. */ areq->tsgl_entries = af_alg_count_tsgl(sk, processed, processed - as); if (!areq->tsgl_entries) areq->tsgl_entries = 1; areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl), areq->tsgl_entries), GFP_KERNEL); if (!areq->tsgl) { err = -ENOMEM; goto free; } sg_init_table(areq->tsgl, areq->tsgl_entries); /* Release TX SGL, except for tag data and reassign tag data. */ af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as); /* chain the areq TX SGL holding the tag with RX SGL */ if (usedpages) { /* RX SGL present */ struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl; sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1); sg_chain(sgl_prev->sg, sgl_prev->npages + 1, areq->tsgl); } else /* no RX SGL present (e.g. authentication only) */ rsgl_src = areq->tsgl; } /* Initialize the crypto operation */ aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src, areq->first_rsgl.sgl.sg, used, ctx->iv); aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen); aead_request_set_tfm(&areq->cra_u.aead_req, tfm); 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 = outlen; aead_request_set_callback(&areq->cra_u.aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, af_alg_async_cb, areq); err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : crypto_aead_decrypt(&areq->cra_u.aead_req); /* AIO operation in progress */ if (err == -EINPROGRESS) return -EIOCBQUEUED; sock_put(sk); } else { /* Synchronous operation */ aead_request_set_callback(&areq->cra_u.aead_req, CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &ctx->wait); err = crypto_wait_req(ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : crypto_aead_decrypt(&areq->cra_u.aead_req), &ctx->wait); } free: af_alg_free_resources(areq); return err ? err : outlen; } static int aead_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 = _aead_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 || err == -EBADMSG || !ret) ret = err; goto out; } ret += err; } out: af_alg_wmem_wakeup(sk); release_sock(sk); return ret; } static struct proto_ops algif_aead_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 = aead_sendmsg, .sendpage = af_alg_sendpage, .recvmsg = aead_recvmsg, .poll = af_alg_poll, }; static int aead_check_key(struct socket *sock) { int err = 0; struct sock *psk; struct alg_sock *pask; struct aead_tfm *tfm; struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); lock_sock(sk); if (!atomic_read(&ask->nokey_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_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) 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 aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg, size_t size) { int err; err = aead_check_key(sock); if (err) return err; return aead_sendmsg(sock, msg, size); } static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page, int offset, size_t size, int flags) { int err; err = aead_check_key(sock); if (err) return err; return af_alg_sendpage(sock, page, offset, size, flags); } static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg, size_t ignored, int flags) { int err; err = aead_check_key(sock); if (err) return err; return aead_recvmsg(sock, msg, ignored, flags); } static struct proto_ops algif_aead_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 = aead_sendmsg_nokey, .sendpage = aead_sendpage_nokey, .recvmsg = aead_recvmsg_nokey, .poll = af_alg_poll, }; static void *aead_bind(const char *name, u32 type, u32 mask) { struct aead_tfm *tfm; struct crypto_aead *aead; struct crypto_sync_skcipher *null_tfm; tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); if (!tfm) return ERR_PTR(-ENOMEM); aead = crypto_alloc_aead(name, type, mask); if (IS_ERR(aead)) { kfree(tfm); return ERR_CAST(aead); } null_tfm = crypto_get_default_null_skcipher(); if (IS_ERR(null_tfm)) { crypto_free_aead(aead); kfree(tfm); return ERR_CAST(null_tfm); } tfm->aead = aead; tfm->null_tfm = null_tfm; return tfm; } static void aead_release(void *private) { struct aead_tfm *tfm = private; crypto_free_aead(tfm->aead); crypto_put_default_null_skcipher(); kfree(tfm); } static int aead_setauthsize(void *private, unsigned int authsize) { struct aead_tfm *tfm = private; return crypto_aead_setauthsize(tfm->aead, authsize); } static int aead_setkey(void *private, const u8 *key, unsigned int keylen) { struct aead_tfm *tfm = private; return crypto_aead_setkey(tfm->aead, key, keylen); } static void aead_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 aead_tfm *aeadc = pask->private; struct crypto_aead *tfm = aeadc->aead; unsigned int ivlen = crypto_aead_ivsize(tfm); af_alg_pull_tsgl(sk, ctx->used, NULL, 0); sock_kzfree_s(sk, ctx->iv, ivlen); sock_kfree_s(sk, ctx, ctx->len); af_alg_release_parent(sk); } static int aead_accept_parent_nokey(void *private, struct sock *sk) { struct af_alg_ctx *ctx; struct alg_sock *ask = alg_sk(sk); struct aead_tfm *tfm = private; struct crypto_aead *aead = tfm->aead; unsigned int len = sizeof(*ctx); unsigned int ivlen = crypto_aead_ivsize(aead); ctx = sock_kmalloc(sk, len, GFP_KERNEL); if (!ctx) return -ENOMEM; memset(ctx, 0, len); ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL); if (!ctx->iv) { sock_kfree_s(sk, ctx, len); return -ENOMEM; } memset(ctx->iv, 0, ivlen); INIT_LIST_HEAD(&ctx->tsgl_list); ctx->len = len; crypto_init_wait(&ctx->wait); ask->private = ctx; sk->sk_destruct = aead_sock_destruct; return 0; } static int aead_accept_parent(void *private, struct sock *sk) { struct aead_tfm *tfm = private; if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) return -ENOKEY; return aead_accept_parent_nokey(private, sk); } static const struct af_alg_type algif_type_aead = { .bind = aead_bind, .release = aead_release, .setkey = aead_setkey, .setauthsize = aead_setauthsize, .accept = aead_accept_parent, .accept_nokey = aead_accept_parent_nokey, .ops = &algif_aead_ops, .ops_nokey = &algif_aead_ops_nokey, .name = "aead", .owner = THIS_MODULE }; static int __init algif_aead_init(void) { return af_alg_register_type(&algif_type_aead); } static void __exit algif_aead_exit(void) { int err = af_alg_unregister_type(&algif_type_aead); BUG_ON(err); } module_init(algif_aead_init); module_exit(algif_aead_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");