/* * 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. * * This file is derived from algif_skcipher.c. * * 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/scatterwalk.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 aead_sg_list { unsigned int cur; struct scatterlist sg[ALG_MAX_PAGES]; }; struct aead_ctx { struct aead_sg_list tsgl; /* * RSGL_MAX_ENTRIES is an artificial limit where user space at maximum * can cause the kernel to allocate RSGL_MAX_ENTRIES * ALG_MAX_PAGES * pages */ #define RSGL_MAX_ENTRIES ALG_MAX_PAGES struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES]; void *iv; struct af_alg_completion completion; unsigned long used; unsigned int len; bool more; bool merge; bool enc; size_t aead_assoclen; struct aead_request aead_req; }; static inline int aead_sndbuf(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) - ctx->used, 0); } static inline bool aead_writable(struct sock *sk) { return PAGE_SIZE <= aead_sndbuf(sk); } static inline bool aead_sufficient_data(struct aead_ctx *ctx) { unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req)); return (ctx->used >= (ctx->aead_assoclen + (ctx->enc ? 0 : as))); } static void aead_put_sgl(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct aead_sg_list *sgl = &ctx->tsgl; struct scatterlist *sg = sgl->sg; unsigned int i; for (i = 0; i < sgl->cur; i++) { if (!sg_page(sg + i)) continue; put_page(sg_page(sg + i)); sg_assign_page(sg + i, NULL); } sgl->cur = 0; ctx->used = 0; ctx->more = 0; ctx->merge = 0; } static void aead_wmem_wakeup(struct sock *sk) { struct socket_wq *wq; if (!aead_writable(sk)) return; rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); if (wq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); rcu_read_unlock(); } static int aead_wait_for_data(struct sock *sk, unsigned flags) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; long timeout; DEFINE_WAIT(wait); int err = -ERESTARTSYS; if (flags & MSG_DONTWAIT) return -EAGAIN; set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); for (;;) { if (signal_pending(current)) break; prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); timeout = MAX_SCHEDULE_TIMEOUT; if (sk_wait_event(sk, &timeout, !ctx->more)) { err = 0; break; } } finish_wait(sk_sleep(sk), &wait); clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); return err; } static void aead_data_wakeup(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; struct socket_wq *wq; if (ctx->more) return; if (!ctx->used) return; rcu_read_lock(); wq = rcu_dereference(sk->sk_wq); if (wq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | POLLRDNORM | POLLRDBAND); sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); rcu_read_unlock(); } 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 aead_ctx *ctx = ask->private; unsigned ivsize = crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req)); struct aead_sg_list *sgl = &ctx->tsgl; struct af_alg_control con = {}; long copied = 0; bool enc = 0; bool init = 0; int err = -EINVAL; if (msg->msg_controllen) { err = af_alg_cmsg_send(msg, &con); if (err) return err; init = 1; switch (con.op) { case ALG_OP_ENCRYPT: enc = 1; break; case ALG_OP_DECRYPT: enc = 0; break; default: return -EINVAL; } if (con.iv && con.iv->ivlen != ivsize) return -EINVAL; } lock_sock(sk); if (!ctx->more && ctx->used) goto unlock; if (init) { ctx->enc = enc; if (con.iv) memcpy(ctx->iv, con.iv->iv, ivsize); ctx->aead_assoclen = con.aead_assoclen; } while (size) { unsigned long len = size; struct scatterlist *sg = NULL; /* use the existing memory in an allocated page */ if (ctx->merge) { sg = sgl->sg + sgl->cur - 1; len = min_t(unsigned long, len, PAGE_SIZE - sg->offset - sg->length); err = memcpy_from_msg(page_address(sg_page(sg)) + sg->offset + sg->length, msg, len); if (err) goto unlock; sg->length += len; ctx->merge = (sg->offset + sg->length) & (PAGE_SIZE - 1); ctx->used += len; copied += len; size -= len; continue; } if (!aead_writable(sk)) { /* user space sent too much data */ aead_put_sgl(sk); err = -EMSGSIZE; goto unlock; } /* allocate a new page */ len = min_t(unsigned long, size, aead_sndbuf(sk)); while (len) { int plen = 0; if (sgl->cur >= ALG_MAX_PAGES) { aead_put_sgl(sk); err = -E2BIG; goto unlock; } sg = sgl->sg + sgl->cur; plen = min_t(int, len, PAGE_SIZE); sg_assign_page(sg, alloc_page(GFP_KERNEL)); err = -ENOMEM; if (!sg_page(sg)) goto unlock; err = memcpy_from_msg(page_address(sg_page(sg)), msg, plen); if (err) { __free_page(sg_page(sg)); sg_assign_page(sg, NULL); goto unlock; } sg->offset = 0; sg->length = plen; len -= plen; ctx->used += plen; copied += plen; sgl->cur++; size -= plen; ctx->merge = plen & (PAGE_SIZE - 1); } } err = 0; ctx->more = msg->msg_flags & MSG_MORE; if (!ctx->more && !aead_sufficient_data(ctx)) { aead_put_sgl(sk); err = -EMSGSIZE; } unlock: aead_data_wakeup(sk); release_sock(sk); return err ?: copied; } static ssize_t aead_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 aead_ctx *ctx = ask->private; struct aead_sg_list *sgl = &ctx->tsgl; int err = -EINVAL; if (flags & MSG_SENDPAGE_NOTLAST) flags |= MSG_MORE; if (sgl->cur >= ALG_MAX_PAGES) return -E2BIG; lock_sock(sk); if (!ctx->more && ctx->used) goto unlock; if (!size) goto done; if (!aead_writable(sk)) { /* user space sent too much data */ aead_put_sgl(sk); err = -EMSGSIZE; goto unlock; } ctx->merge = 0; get_page(page); sg_set_page(sgl->sg + sgl->cur, page, size, offset); sgl->cur++; ctx->used += size; err = 0; done: ctx->more = flags & MSG_MORE; if (!ctx->more && !aead_sufficient_data(ctx)) { aead_put_sgl(sk); err = -EMSGSIZE; } unlock: aead_data_wakeup(sk); release_sock(sk); return err ?: size; } 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 aead_ctx *ctx = ask->private; unsigned bs = crypto_aead_blocksize(crypto_aead_reqtfm(&ctx->aead_req)); unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req)); struct aead_sg_list *sgl = &ctx->tsgl; struct scatterlist *sg = NULL; struct scatterlist assoc[ALG_MAX_PAGES]; size_t assoclen = 0; unsigned int i = 0; int err = -EINVAL; unsigned long used = 0; size_t outlen = 0; size_t usedpages = 0; unsigned int cnt = 0; /* Limit number of IOV blocks to be accessed below */ if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES) return -ENOMSG; lock_sock(sk); /* * AEAD memory structure: For encryption, the tag is appended to the * ciphertext which implies that the memory allocated for the ciphertext * must be increased by the tag length. For decryption, the tag * is expected to be concatenated to the ciphertext. The plaintext * therefore has a memory size of the ciphertext minus the tag length. * * The memory structure for cipher operation has the following * structure: * AEAD encryption input: assoc data || plaintext * AEAD encryption output: cipherntext || auth tag * AEAD decryption input: assoc data || ciphertext || auth tag * AEAD decryption output: plaintext */ if (ctx->more) { err = aead_wait_for_data(sk, flags); if (err) goto unlock; } used = ctx->used; /* * Make sure sufficient data is present -- note, the same check is * 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(ctx)) goto unlock; /* * The cipher operation input data is reduced by the associated data * length as this data is processed separately later on. */ used -= ctx->aead_assoclen; if (ctx->enc) { /* round up output buffer to multiple of block size */ outlen = ((used + bs - 1) / bs * bs); /* add the size needed for the auth tag to be created */ outlen += as; } else { /* output data size is input without the authentication tag */ outlen = used - as; /* round up output buffer to multiple of block size */ outlen = ((outlen + bs - 1) / bs * bs); } /* convert iovecs of output buffers into scatterlists */ while (iov_iter_count(&msg->msg_iter)) { size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter), (outlen - usedpages)); /* make one iovec available as scatterlist */ err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter, seglen); if (err < 0) goto unlock; usedpages += err; /* chain the new scatterlist with previous one */ if (cnt) af_alg_link_sg(&ctx->rsgl[cnt-1], &ctx->rsgl[cnt]); /* we do not need more iovecs as we have sufficient memory */ if (outlen <= usedpages) break; iov_iter_advance(&msg->msg_iter, err); cnt++; } err = -EINVAL; /* ensure output buffer is sufficiently large */ if (usedpages < outlen) goto unlock; sg_init_table(assoc, ALG_MAX_PAGES); assoclen = ctx->aead_assoclen; /* * Split scatterlist into two: first part becomes AD, second part * is plaintext / ciphertext. The first part is assigned to assoc * scatterlist. When this loop finishes, sg points to the start of the * plaintext / ciphertext. */ for (i = 0; i < ctx->tsgl.cur; i++) { sg = sgl->sg + i; if (sg->length <= assoclen) { /* AD is larger than one page */ sg_set_page(assoc + i, sg_page(sg), sg->length, sg->offset); assoclen -= sg->length; if (i >= ctx->tsgl.cur) goto unlock; } else if (!assoclen) { /* current page is to start of plaintext / ciphertext */ if (i) /* AD terminates at page boundary */ sg_mark_end(assoc + i - 1); else /* AD size is zero */ sg_mark_end(assoc); break; } else { /* AD does not terminate at page boundary */ sg_set_page(assoc + i, sg_page(sg), assoclen, sg->offset); sg_mark_end(assoc + i); /* plaintext / ciphertext starts after AD */ sg->length -= assoclen; sg->offset += assoclen; break; } } aead_request_set_assoc(&ctx->aead_req, assoc, ctx->aead_assoclen); aead_request_set_crypt(&ctx->aead_req, sg, ctx->rsgl[0].sg, used, ctx->iv); err = af_alg_wait_for_completion(ctx->enc ? crypto_aead_encrypt(&ctx->aead_req) : crypto_aead_decrypt(&ctx->aead_req), &ctx->completion); if (err) { /* EBADMSG implies a valid cipher operation took place */ if (err == -EBADMSG) aead_put_sgl(sk); goto unlock; } aead_put_sgl(sk); err = 0; unlock: for (i = 0; i < cnt; i++) af_alg_free_sg(&ctx->rsgl[i]); aead_wmem_wakeup(sk); release_sock(sk); return err ? err : outlen; } static unsigned int aead_poll(struct file *file, struct socket *sock, poll_table *wait) { struct sock *sk = sock->sk; struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; unsigned int mask; sock_poll_wait(file, sk_sleep(sk), wait); mask = 0; if (!ctx->more) mask |= POLLIN | POLLRDNORM; if (aead_writable(sk)) mask |= POLLOUT | POLLWRNORM | POLLWRBAND; return mask; } 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, .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 = aead_sendmsg, .sendpage = aead_sendpage, .recvmsg = aead_recvmsg, .poll = aead_poll, }; static void *aead_bind(const char *name, u32 type, u32 mask) { return crypto_alloc_aead(name, type, mask); } static void aead_release(void *private) { crypto_free_aead(private); } static int aead_setauthsize(void *private, unsigned int authsize) { return crypto_aead_setauthsize(private, authsize); } static int aead_setkey(void *private, const u8 *key, unsigned int keylen) { return crypto_aead_setkey(private, key, keylen); } static void aead_sock_destruct(struct sock *sk) { struct alg_sock *ask = alg_sk(sk); struct aead_ctx *ctx = ask->private; unsigned int ivlen = crypto_aead_ivsize( crypto_aead_reqtfm(&ctx->aead_req)); aead_put_sgl(sk); sock_kzfree_s(sk, ctx->iv, ivlen); sock_kfree_s(sk, ctx, ctx->len); af_alg_release_parent(sk); } static int aead_accept_parent(void *private, struct sock *sk) { struct aead_ctx *ctx; struct alg_sock *ask = alg_sk(sk); unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private); unsigned int ivlen = crypto_aead_ivsize(private); 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); ctx->len = len; ctx->used = 0; ctx->more = 0; ctx->merge = 0; ctx->enc = 0; ctx->tsgl.cur = 0; ctx->aead_assoclen = 0; af_alg_init_completion(&ctx->completion); sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES); ask->private = ctx; aead_request_set_tfm(&ctx->aead_req, private); aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_complete, &ctx->completion); sk->sk_destruct = aead_sock_destruct; return 0; } 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, .ops = &algif_aead_ops, .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");