// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * algif_hash: User-space interface for hash algorithms
 *
 * This file provides the user-space API for hash algorithms.
 *
 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <crypto/hash.h>
#include <crypto/if_alg.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/net.h>
#include <net/sock.h>

struct hash_ctx {
        struct af_alg_sgl sgl;

        u8 *result;

        struct crypto_wait wait;

        unsigned int len;
        bool more;

        struct ahash_request req;
};

static int hash_alloc_result(struct sock *sk, struct hash_ctx *ctx)
{
        unsigned ds;

        if (ctx->result)
                return 0;

        ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

        ctx->result = sock_kmalloc(sk, ds, GFP_KERNEL);
        if (!ctx->result)
                return -ENOMEM;

        memset(ctx->result, 0, ds);

        return 0;
}

static void hash_free_result(struct sock *sk, struct hash_ctx *ctx)
{
        unsigned ds;

        if (!ctx->result)
                return;

        ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));

        sock_kzfree_s(sk, ctx->result, ds);
        ctx->result = NULL;
}

static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
                        size_t ignored)
{
        struct sock *sk = sock->sk;
        struct alg_sock *ask = alg_sk(sk);
        struct hash_ctx *ctx = ask->private;
        ssize_t copied = 0;
        size_t len, max_pages, npages;
        bool continuing, need_init = false;
        int err;

        max_pages = min_t(size_t, ALG_MAX_PAGES,
                          DIV_ROUND_UP(sk->sk_sndbuf, PAGE_SIZE));

        lock_sock(sk);
        continuing = ctx->more;

        if (!continuing) {
                /* Discard a previous request that wasn't marked MSG_MORE. */
                hash_free_result(sk, ctx);
                if (!msg_data_left(msg))
                        goto done; /* Zero-length; don't start new req */
                need_init = true;
        } else if (!msg_data_left(msg)) {
                /*
                 * No data - finalise the prev req if MSG_MORE so any error
                 * comes out here.
                 */
                if (!(msg->msg_flags & MSG_MORE)) {
                        err = hash_alloc_result(sk, ctx);
                        if (err)
                                goto unlock_free_result;
                        ahash_request_set_crypt(&ctx->req, NULL,
                                                ctx->result, 0);
                        err = crypto_wait_req(crypto_ahash_final(&ctx->req),
                                              &ctx->wait);
                        if (err)
                                goto unlock_free_result;
                }
                goto done_more;
        }

        while (msg_data_left(msg)) {
                ctx->sgl.sgt.sgl = ctx->sgl.sgl;
                ctx->sgl.sgt.nents = 0;
                ctx->sgl.sgt.orig_nents = 0;

                err = -EIO;
                npages = iov_iter_npages(&msg->msg_iter, max_pages);
                if (npages == 0)
                        goto unlock_free;

                sg_init_table(ctx->sgl.sgl, npages);

                ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter);

                err = extract_iter_to_sg(&msg->msg_iter, LONG_MAX,
                                         &ctx->sgl.sgt, npages, 0);
                if (err < 0)
                        goto unlock_free;
                len = err;
                sg_mark_end(ctx->sgl.sgt.sgl + ctx->sgl.sgt.nents - 1);

                if (!msg_data_left(msg)) {
                        err = hash_alloc_result(sk, ctx);
                        if (err)
                                goto unlock_free;
                }

                ahash_request_set_crypt(&ctx->req, ctx->sgl.sgt.sgl,
                                        ctx->result, len);

                if (!msg_data_left(msg) && !continuing &&
                    !(msg->msg_flags & MSG_MORE)) {
                        err = crypto_ahash_digest(&ctx->req);
                } else {
                        if (need_init) {
                                err = crypto_wait_req(
                                        crypto_ahash_init(&ctx->req),
                                        &ctx->wait);
                                if (err)
                                        goto unlock_free;
                                need_init = false;
                        }

                        if (msg_data_left(msg) || (msg->msg_flags & MSG_MORE))
                                err = crypto_ahash_update(&ctx->req);
                        else
                                err = crypto_ahash_finup(&ctx->req);
                        continuing = true;
                }

                err = crypto_wait_req(err, &ctx->wait);
                if (err)
                        goto unlock_free;

                copied += len;
                af_alg_free_sg(&ctx->sgl);
        }

done_more:
        ctx->more = msg->msg_flags & MSG_MORE;
done:
        err = 0;
unlock:
        release_sock(sk);
        return copied ?: err;

unlock_free:
        af_alg_free_sg(&ctx->sgl);
unlock_free_result:
        hash_free_result(sk, ctx);
        ctx->more = false;
        goto unlock;
}

static int hash_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
                        int flags)
{
        struct sock *sk = sock->sk;
        struct alg_sock *ask = alg_sk(sk);
        struct hash_ctx *ctx = ask->private;
        unsigned ds = crypto_ahash_digestsize(crypto_ahash_reqtfm(&ctx->req));
        bool result;
        int err;

        if (len > ds)
                len = ds;
        else if (len < ds)
                msg->msg_flags |= MSG_TRUNC;

        lock_sock(sk);
        result = ctx->result;
        err = hash_alloc_result(sk, ctx);
        if (err)
                goto unlock;

        ahash_request_set_crypt(&ctx->req, NULL, ctx->result, 0);

        if (!result && !ctx->more) {
                err = crypto_wait_req(crypto_ahash_init(&ctx->req),
                                      &ctx->wait);
                if (err)
                        goto unlock;
        }

        if (!result || ctx->more) {
                ctx->more = false;
                err = crypto_wait_req(crypto_ahash_final(&ctx->req),
                                      &ctx->wait);
                if (err)
                        goto unlock;
        }

        err = memcpy_to_msg(msg, ctx->result, len);

unlock:
        hash_free_result(sk, ctx);
        release_sock(sk);

        return err ?: len;
}

static int hash_accept(struct socket *sock, struct socket *newsock,
                       struct proto_accept_arg *arg)
{
        struct sock *sk = sock->sk;
        struct alg_sock *ask = alg_sk(sk);
        struct hash_ctx *ctx = ask->private;
        struct ahash_request *req = &ctx->req;
        struct crypto_ahash *tfm;
        struct sock *sk2;
        struct alg_sock *ask2;
        struct hash_ctx *ctx2;
        char *state;
        bool more;
        int err;

        tfm = crypto_ahash_reqtfm(req);
        state = kmalloc(crypto_ahash_statesize(tfm), GFP_KERNEL);
        err = -ENOMEM;
        if (!state)
                goto out;

        lock_sock(sk);
        more = ctx->more;
        err = more ? crypto_ahash_export(req, state) : 0;
        release_sock(sk);

        if (err)
                goto out_free_state;

        err = af_alg_accept(ask->parent, newsock, arg);
        if (err)
                goto out_free_state;

        sk2 = newsock->sk;
        ask2 = alg_sk(sk2);
        ctx2 = ask2->private;
        ctx2->more = more;

        if (!more)
                goto out_free_state;

        err = crypto_ahash_import(&ctx2->req, state);

out_free_state:
        kfree_sensitive(state);

out:
        return err;
}

static struct proto_ops algif_hash_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,

        .release        =       af_alg_release,
        .sendmsg        =       hash_sendmsg,
        .recvmsg        =       hash_recvmsg,
        .accept         =       hash_accept,
};

static int hash_check_key(struct socket *sock)
{
        int err = 0;
        struct sock *psk;
        struct alg_sock *pask;
        struct crypto_ahash *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_ahash_get_flags(tfm) & 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 hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
                              size_t size)
{
        int err;

        err = hash_check_key(sock);
        if (err)
                return err;

        return hash_sendmsg(sock, msg, size);
}

static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
                              size_t ignored, int flags)
{
        int err;

        err = hash_check_key(sock);
        if (err)
                return err;

        return hash_recvmsg(sock, msg, ignored, flags);
}

static int hash_accept_nokey(struct socket *sock, struct socket *newsock,
                             struct proto_accept_arg *arg)
{
        int err;

        err = hash_check_key(sock);
        if (err)
                return err;

        return hash_accept(sock, newsock, arg);
}

static struct proto_ops algif_hash_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,

        .release        =       af_alg_release,
        .sendmsg        =       hash_sendmsg_nokey,
        .recvmsg        =       hash_recvmsg_nokey,
        .accept         =       hash_accept_nokey,
};

static void *hash_bind(const char *name, u32 type, u32 mask)
{
        return crypto_alloc_ahash(name, type, mask);
}

static void hash_release(void *private)
{
        crypto_free_ahash(private);
}

static int hash_setkey(void *private, const u8 *key, unsigned int keylen)
{
        return crypto_ahash_setkey(private, key, keylen);
}

static void hash_sock_destruct(struct sock *sk)
{
        struct alg_sock *ask = alg_sk(sk);
        struct hash_ctx *ctx = ask->private;

        hash_free_result(sk, ctx);
        sock_kfree_s(sk, ctx, ctx->len);
        af_alg_release_parent(sk);
}

static int hash_accept_parent_nokey(void *private, struct sock *sk)
{
        struct crypto_ahash *tfm = private;
        struct alg_sock *ask = alg_sk(sk);
        struct hash_ctx *ctx;
        unsigned int len = sizeof(*ctx) + crypto_ahash_reqsize(tfm);

        ctx = sock_kmalloc(sk, len, GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        memset(ctx, 0, len);
        ctx->len = len;
        crypto_init_wait(&ctx->wait);

        ask->private = ctx;

        ahash_request_set_tfm(&ctx->req, tfm);
        ahash_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                   crypto_req_done, &ctx->wait);

        sk->sk_destruct = hash_sock_destruct;

        return 0;
}

static int hash_accept_parent(void *private, struct sock *sk)
{
        struct crypto_ahash *tfm = private;

        if (crypto_ahash_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
                return -ENOKEY;

        return hash_accept_parent_nokey(private, sk);
}

static const struct af_alg_type algif_type_hash = {
        .bind           =       hash_bind,
        .release        =       hash_release,
        .setkey         =       hash_setkey,
        .accept         =       hash_accept_parent,
        .accept_nokey   =       hash_accept_parent_nokey,
        .ops            =       &algif_hash_ops,
        .ops_nokey      =       &algif_hash_ops_nokey,
        .name           =       "hash",
        .owner          =       THIS_MODULE
};

static int __init algif_hash_init(void)
{
        return af_alg_register_type(&algif_type_hash);
}

static void __exit algif_hash_exit(void)
{
        int err = af_alg_unregister_type(&algif_type_hash);
        BUG_ON(err);
}

module_init(algif_hash_init);
module_exit(algif_hash_exit);
MODULE_DESCRIPTION("Userspace interface for hash algorithms");
MODULE_LICENSE("GPL");