This patch adds the user space interface for asymmetric ciphers. The
interface allows the use of sendmsg as well as vmsplice to provide data.
Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
---
crypto/algif_akcipher.c | 542 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 542 insertions(+)
create mode 100644 crypto/algif_akcipher.c
diff --git a/crypto/algif_akcipher.c b/crypto/algif_akcipher.c
new file mode 100644
index 0000000..7c58e9b
--- /dev/null
+++ b/crypto/algif_akcipher.c
@@ -0,0 +1,542 @@
+/*
+ * algif_akcipher: User-space interface for asymmetric cipher algorithms
+ *
+ * Copyright (C) 2015, Stephan Mueller <smueller@xxxxxxxxxx>
+ *
+ * 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.
+ */
+
+#include <crypto/akcipher.h>
+#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 akcipher_sg_list {
+ unsigned int cur;
+ struct scatterlist sg[ALG_MAX_PAGES];
+};
+
+struct akcipher_ctx {
+ struct akcipher_sg_list tsgl;
+ struct af_alg_sgl rsgl[ALG_MAX_PAGES];
+
+ struct af_alg_completion completion;
+
+ unsigned long used;
+
+ unsigned int len;
+ bool more;
+ bool merge;
+ int op;
+
+ struct akcipher_request req;
+};
+
+static inline int akcipher_sndbuf(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_ctx *ctx = ask->private;
+
+ return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
+ ctx->used, 0);
+}
+
+static inline bool akcipher_writable(struct sock *sk)
+{
+ return PAGE_SIZE <= akcipher_sndbuf(sk);
+}
+
+static inline int akcipher_calcsize(struct akcipher_ctx *ctx)
+{
+ return crypto_akcipher_maxsize(crypto_akcipher_reqtfm(&ctx->req));
+}
+
+static void akcipher_put_sgl(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_ctx *ctx = ask->private;
+ struct akcipher_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);
+ }
+ sg_init_table(sg, ALG_MAX_PAGES);
+ sgl->cur = 0;
+ ctx->used = 0;
+ ctx->more = 0;
+ ctx->merge = 0;
+}
+
+static void akcipher_wmem_wakeup(struct sock *sk)
+{
+ struct socket_wq *wq;
+
+ if (!akcipher_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 akcipher_wait_for_data(struct sock *sk, unsigned flags)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_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 akcipher_data_wakeup(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_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 akcipher_sendmsg(struct socket *sock, struct msghdr *msg,
+ size_t size)
+{
+ struct sock *sk = sock->sk;
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_ctx *ctx = ask->private;
+ struct akcipher_sg_list *sgl = &ctx->tsgl;
+ struct af_alg_control con = {};
+ long copied = 0;
+ int op = 0;
+ bool init = 0;
+ int err;
+
+ if (msg->msg_controllen) {
+ err = af_alg_cmsg_send(msg, &con);
+ if (err)
+ return err;
+
+ init = 1;
+ switch (con.op) {
+ case ALG_OP_VERIFY:
+ case ALG_OP_SIGN:
+ case ALG_OP_ENCRYPT:
+ case ALG_OP_DECRYPT:
+ op = con.op;
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ lock_sock(sk);
+ if (!ctx->more && ctx->used)
+ goto unlock;
+
+ if (init)
+ ctx->op = op;
+
+ 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 (!akcipher_writable(sk)) {
+ /* user space sent too much data */
+ akcipher_put_sgl(sk);
+ err = -EMSGSIZE;
+ goto unlock;
+ }
+
+ /* allocate a new page */
+ len = min_t(unsigned long, size, akcipher_sndbuf(sk));
+ while (len) {
+ int plen = 0;
+
+ if (sgl->cur >= ALG_MAX_PAGES) {
+ akcipher_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));
+ if (!sg_page(sg)) {
+ err = -ENOMEM;
+ 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;
+
+unlock:
+ akcipher_data_wakeup(sk);
+ release_sock(sk);
+
+ return err ?: copied;
+}
+
+static ssize_t akcipher_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 akcipher_ctx *ctx = ask->private;
+ struct akcipher_sg_list *sgl = &ctx->tsgl;
+ int err = 0;
+
+ 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 (!akcipher_writable(sk)) {
+ /* user space sent too much data */
+ akcipher_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;
+
+done:
+ ctx->more = flags & MSG_MORE;
+unlock:
+ akcipher_data_wakeup(sk);
+ release_sock(sk);
+
+ return err ? err : size;
+}
+
+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 akcipher_ctx *ctx = ask->private;
+ struct akcipher_sg_list *sgl = &ctx->tsgl;
+ unsigned int i = 0;
+ int err;
+ unsigned long used = 0;
+ size_t usedpages = 0;
+ unsigned int cnt = 0;
+
+ /* Limit number of IOV blocks to be accessed below */
+ if (msg->msg_iter.nr_segs > ALG_MAX_PAGES)
+ return -ENOMSG;
+
+ lock_sock(sk);
+
+ if (ctx->more) {
+ err = akcipher_wait_for_data(sk, flags);
+ if (err)
+ goto unlock;
+ }
+
+ used = ctx->used;
+
+ /* convert iovecs of output buffers into scatterlists */
+ while (iov_iter_count(&msg->msg_iter)) {
+ /* make one iovec available as scatterlist */
+ err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
+ iov_iter_count(&msg->msg_iter));
+ 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]);
+
+ iov_iter_advance(&msg->msg_iter, err);
+ cnt++;
+ }
+
+ /* ensure output buffer is sufficiently large */
+ if (usedpages < akcipher_calcsize(ctx)) {
+ err = -EMSGSIZE;
+ goto unlock;
+ }
+
+ sg_mark_end(sgl->sg + sgl->cur - 1);
+
+ akcipher_request_set_crypt(&ctx->req, sgl->sg, ctx->rsgl[0].sg, used,
+ usedpages);
+ switch (ctx->op) {
+ case ALG_OP_VERIFY:
+ err = crypto_akcipher_verify(&ctx->req);
+ break;
+ case ALG_OP_SIGN:
+ err = crypto_akcipher_sign(&ctx->req);
+ break;
+ case ALG_OP_ENCRYPT:
+ err = crypto_akcipher_encrypt(&ctx->req);
+ break;
+ case ALG_OP_DECRYPT:
+ err = crypto_akcipher_decrypt(&ctx->req);
+ break;
+ default:
+ err = -EFAULT;
+ goto unlock;
+ }
+
+ err = af_alg_wait_for_completion(err, &ctx->completion);
+
+ if (err) {
+ /* EBADMSG implies a valid cipher operation took place */
+ if (err == -EBADMSG)
+ akcipher_put_sgl(sk);
+ goto unlock;
+ }
+
+ akcipher_put_sgl(sk);
+
+unlock:
+ for (i = 0; i < cnt; i++)
+ af_alg_free_sg(&ctx->rsgl[i]);
+
+ akcipher_wmem_wakeup(sk);
+ release_sock(sk);
+
+ return err ? err : ctx->req.dst_len;
+}
+
+static unsigned int akcipher_poll(struct file *file, struct socket *sock,
+ poll_table *wait)
+{
+ struct sock *sk = sock->sk;
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_ctx *ctx = ask->private;
+ unsigned int mask = 0;
+
+ sock_poll_wait(file, sk_sleep(sk), wait);
+
+ if (!ctx->more)
+ mask |= POLLIN | POLLRDNORM;
+
+ if (akcipher_writable(sk))
+ mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
+
+ return mask;
+}
+
+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,
+ .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,
+ .sendpage = akcipher_sendpage,
+ .recvmsg = akcipher_recvmsg,
+ .poll = akcipher_poll,
+};
+
+static void *akcipher_bind(const char *name, u32 type, u32 mask)
+{
+ return crypto_alloc_akcipher(name, type, mask);
+}
+
+static void akcipher_release(void *private)
+{
+ crypto_free_akcipher(private);
+}
+
+static int akcipher_setprivkey(void *private, const u8 *key,
+ unsigned int keylen)
+{
+ return crypto_akcipher_set_priv_key(private, key, keylen);
+}
+
+static int akcipher_setpubkey(void *private, const u8 *key, unsigned int keylen)
+{
+ return crypto_akcipher_set_pub_key(private, key, keylen);
+}
+
+static void akcipher_sock_destruct(struct sock *sk)
+{
+ struct alg_sock *ask = alg_sk(sk);
+ struct akcipher_ctx *ctx = ask->private;
+
+ akcipher_put_sgl(sk);
+ sock_kfree_s(sk, ctx, ctx->len);
+ af_alg_release_parent(sk);
+}
+
+static int akcipher_accept_parent(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);
+
+ ctx = sock_kmalloc(sk, len, GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+ memset(ctx, 0, len);
+
+ ctx->len = len;
+ ctx->used = 0;
+ ctx->more = 0;
+ ctx->merge = 0;
+ ctx->op = 0;
+ ctx->tsgl.cur = 0;
+ af_alg_init_completion(&ctx->completion);
+ sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
+
+ ask->private = ctx;
+
+ akcipher_request_set_tfm(&ctx->req, private);
+ akcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+ af_alg_complete, &ctx->completion);
+
+ sk->sk_destruct = akcipher_sock_destruct;
+
+ return 0;
+}
+
+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,
+ .ops = &algif_akcipher_ops,
+ .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@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Asymmetric kernel crypto API user space interface");
--
2.5.0
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