/*
 * Asynchronous Cryptographic Hash operations.
 *
 * This is the asynchronous version of hash.c with notification of
 * completion via a callback.
 *
 * Copyright (c) 2008 Loc Ho <lho@amcc.com>
 *
 * 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/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/cryptouser.h>
#include <linux/compiler.h>
#include <net/netlink.h>

#include "internal.h"

struct ahash_request_priv {
        crypto_completion_t complete;
        void *data;
        u8 *result;
        u32 flags;
        void *ubuf[] CRYPTO_MINALIGN_ATTR;
};

static inline struct ahash_alg *crypto_ahash_alg(struct crypto_ahash *hash)
{
        return container_of(crypto_hash_alg_common(hash), struct ahash_alg,
                            halg);
}

static int hash_walk_next(struct crypto_hash_walk *walk)
{
        unsigned int alignmask = walk->alignmask;
        unsigned int offset = walk->offset;
        unsigned int nbytes = min(walk->entrylen,
                                  ((unsigned int)(PAGE_SIZE)) - offset);

        if (walk->flags & CRYPTO_ALG_ASYNC)
                walk->data = kmap(walk->pg);
        else
                walk->data = kmap_atomic(walk->pg);
        walk->data += offset;

        if (offset & alignmask) {
                unsigned int unaligned = alignmask + 1 - (offset & alignmask);

                if (nbytes > unaligned)
                        nbytes = unaligned;
        }

        walk->entrylen -= nbytes;
        return nbytes;
}

static int hash_walk_new_entry(struct crypto_hash_walk *walk)
{
        struct scatterlist *sg;

        sg = walk->sg;
        walk->offset = sg->offset;
        walk->pg = sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
        walk->offset = offset_in_page(walk->offset);
        walk->entrylen = sg->length;

        if (walk->entrylen > walk->total)
                walk->entrylen = walk->total;
        walk->total -= walk->entrylen;

        return hash_walk_next(walk);
}

int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
{
        unsigned int alignmask = walk->alignmask;
        unsigned int nbytes = walk->entrylen;

        walk->data -= walk->offset;

        if (nbytes && walk->offset & alignmask && !err) {
                walk->offset = ALIGN(walk->offset, alignmask + 1);
                nbytes = min(nbytes,
                             ((unsigned int)(PAGE_SIZE)) - walk->offset);
                walk->entrylen -= nbytes;

                if (nbytes) {
                        walk->data += walk->offset;
                        return nbytes;
                }
        }

        if (walk->flags & CRYPTO_ALG_ASYNC)
                kunmap(walk->pg);
        else {
                kunmap_atomic(walk->data);
                /*
                 * The may sleep test only makes sense for sync users.
                 * Async users don't need to sleep here anyway.
                 */
                crypto_yield(walk->flags);
        }

        if (err)
                return err;

        if (nbytes) {
                walk->offset = 0;
                walk->pg++;
                return hash_walk_next(walk);
        }

        if (!walk->total)
                return 0;

        walk->sg = sg_next(walk->sg);

        return hash_walk_new_entry(walk);
}
EXPORT_SYMBOL_GPL(crypto_hash_walk_done);

int crypto_hash_walk_first(struct ahash_request *req,
                           struct crypto_hash_walk *walk)
{
        walk->total = req->nbytes;

        if (!walk->total) {
                walk->entrylen = 0;
                return 0;
        }

        walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
        walk->sg = req->src;
        walk->flags = req->base.flags & CRYPTO_TFM_REQ_MASK;

        return hash_walk_new_entry(walk);
}
EXPORT_SYMBOL_GPL(crypto_hash_walk_first);

int crypto_ahash_walk_first(struct ahash_request *req,
                            struct crypto_hash_walk *walk)
{
        walk->total = req->nbytes;

        if (!walk->total) {
                walk->entrylen = 0;
                return 0;
        }

        walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
        walk->sg = req->src;
        walk->flags = req->base.flags & CRYPTO_TFM_REQ_MASK;
        walk->flags |= CRYPTO_ALG_ASYNC;

        BUILD_BUG_ON(CRYPTO_TFM_REQ_MASK & CRYPTO_ALG_ASYNC);

        return hash_walk_new_entry(walk);
}
EXPORT_SYMBOL_GPL(crypto_ahash_walk_first);

static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
                                unsigned int keylen)
{
        unsigned long alignmask = crypto_ahash_alignmask(tfm);
        int ret;
        u8 *buffer, *alignbuffer;
        unsigned long absize;

        absize = keylen + alignmask;
        buffer = kmalloc(absize, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;

        alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
        memcpy(alignbuffer, key, keylen);
        ret = tfm->setkey(tfm, alignbuffer, keylen);
        kzfree(buffer);
        return ret;
}

int crypto_ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
                        unsigned int keylen)
{
        unsigned long alignmask = crypto_ahash_alignmask(tfm);
        int err;

        if ((unsigned long)key & alignmask)
                err = ahash_setkey_unaligned(tfm, key, keylen);
        else
                err = tfm->setkey(tfm, key, keylen);

        if (err)
                return err;

        crypto_ahash_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
        return 0;
}
EXPORT_SYMBOL_GPL(crypto_ahash_setkey);

static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
                          unsigned int keylen)
{
        return -ENOSYS;
}

static inline unsigned int ahash_align_buffer_size(unsigned len,
                                                   unsigned long mask)
{
        return len + (mask & ~(crypto_tfm_ctx_alignment() - 1));
}

static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt)
{
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
        unsigned long alignmask = crypto_ahash_alignmask(tfm);
        unsigned int ds = crypto_ahash_digestsize(tfm);
        struct ahash_request_priv *priv;

        priv = kmalloc(sizeof(*priv) + ahash_align_buffer_size(ds, alignmask),
                       (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
                       GFP_KERNEL : GFP_ATOMIC);
        if (!priv)
                return -ENOMEM;

        /*
         * WARNING: Voodoo programming below!
         *
         * The code below is obscure and hard to understand, thus explanation
         * is necessary. See include/crypto/hash.h and include/linux/crypto.h
         * to understand the layout of structures used here!
         *
         * The code here will replace portions of the ORIGINAL request with
         * pointers to new code and buffers so the hashing operation can store
         * the result in aligned buffer. We will call the modified request
         * an ADJUSTED request.
         *
         * The newly mangled request will look as such:
         *
         * req {
         *   .result        = ADJUSTED[new aligned buffer]
         *   .base.complete = ADJUSTED[pointer to completion function]
         *   .base.data     = ADJUSTED[*req (pointer to self)]
         *   .priv          = ADJUSTED[new priv] {
         *           .result   = ORIGINAL(result)
         *           .complete = ORIGINAL(base.complete)
         *           .data     = ORIGINAL(base.data)
         *   }
         */

        priv->result = req->result;
        priv->complete = req->base.complete;
        priv->data = req->base.data;
        priv->flags = req->base.flags;

        /*
         * WARNING: We do not backup req->priv here! The req->priv
         *          is for internal use of the Crypto API and the
         *          user must _NOT_ _EVER_ depend on it's content!
         */

        req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1);
        req->base.complete = cplt;
        req->base.data = req;
        req->priv = priv;

        return 0;
}

static void ahash_restore_req(struct ahash_request *req, int err)
{
        struct ahash_request_priv *priv = req->priv;

        if (!err)
                memcpy(priv->result, req->result,
                       crypto_ahash_digestsize(crypto_ahash_reqtfm(req)));

        /* Restore the original crypto request. */
        req->result = priv->result;

        ahash_request_set_callback(req, priv->flags,
                                   priv->complete, priv->data);
        req->priv = NULL;

        /* Free the req->priv.priv from the ADJUSTED request. */
        kzfree(priv);
}

static void ahash_notify_einprogress(struct ahash_request *req)
{
        struct ahash_request_priv *priv = req->priv;
        struct crypto_async_request oreq;

        oreq.data = priv->data;

        priv->complete(&oreq, -EINPROGRESS);
}

static void ahash_op_unaligned_done(struct crypto_async_request *req, int err)
{
        struct ahash_request *areq = req->data;

        if (err == -EINPROGRESS) {
                ahash_notify_einprogress(areq);
                return;
        }

        /*
         * Restore the original request, see ahash_op_unaligned() for what
         * goes where.
         *
         * The "struct ahash_request *req" here is in fact the "req.base"
         * from the ADJUSTED request from ahash_op_unaligned(), thus as it
         * is a pointer to self, it is also the ADJUSTED "req" .
         */

        /* First copy req->result into req->priv.result */
        ahash_restore_req(areq, err);

        /* Complete the ORIGINAL request. */
        areq->base.complete(&areq->base, err);
}

static int ahash_op_unaligned(struct ahash_request *req,
                              int (*op)(struct ahash_request *))
{
        int err;

        err = ahash_save_req(req, ahash_op_unaligned_done);
        if (err)
                return err;

        err = op(req);
        if (err == -EINPROGRESS || err == -EBUSY)
                return err;

        ahash_restore_req(req, err);

        return err;
}

static int crypto_ahash_op(struct ahash_request *req,
                           int (*op)(struct ahash_request *))
{
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
        unsigned long alignmask = crypto_ahash_alignmask(tfm);

        if ((unsigned long)req->result & alignmask)
                return ahash_op_unaligned(req, op);

        return op(req);
}

int crypto_ahash_final(struct ahash_request *req)
{
        return crypto_ahash_op(req, crypto_ahash_reqtfm(req)->final);
}
EXPORT_SYMBOL_GPL(crypto_ahash_final);

int crypto_ahash_finup(struct ahash_request *req)
{
        return crypto_ahash_op(req, crypto_ahash_reqtfm(req)->finup);
}
EXPORT_SYMBOL_GPL(crypto_ahash_finup);

int crypto_ahash_digest(struct ahash_request *req)
{
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);

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

        return crypto_ahash_op(req, tfm->digest);
}
EXPORT_SYMBOL_GPL(crypto_ahash_digest);

static void ahash_def_finup_done2(struct crypto_async_request *req, int err)
{
        struct ahash_request *areq = req->data;

        if (err == -EINPROGRESS)
                return;

        ahash_restore_req(areq, err);

        areq->base.complete(&areq->base, err);
}

static int ahash_def_finup_finish1(struct ahash_request *req, int err)
{
        if (err)
                goto out;

        req->base.complete = ahash_def_finup_done2;

        err = crypto_ahash_reqtfm(req)->final(req);
        if (err == -EINPROGRESS || err == -EBUSY)
                return err;

out:
        ahash_restore_req(req, err);
        return err;
}

static void ahash_def_finup_done1(struct crypto_async_request *req, int err)
{
        struct ahash_request *areq = req->data;

        if (err == -EINPROGRESS) {
                ahash_notify_einprogress(areq);
                return;
        }

        areq->base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;

        err = ahash_def_finup_finish1(areq, err);
        if (areq->priv)
                return;

        areq->base.complete(&areq->base, err);
}

static int ahash_def_finup(struct ahash_request *req)
{
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
        int err;

        err = ahash_save_req(req, ahash_def_finup_done1);
        if (err)
                return err;

        err = tfm->update(req);
        if (err == -EINPROGRESS || err == -EBUSY)
                return err;

        return ahash_def_finup_finish1(req, err);
}

static int crypto_ahash_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_ahash *hash = __crypto_ahash_cast(tfm);
        struct ahash_alg *alg = crypto_ahash_alg(hash);

        hash->setkey = ahash_nosetkey;

        if (tfm->__crt_alg->cra_type != &crypto_ahash_type)
                return crypto_init_shash_ops_async(tfm);

        hash->init = alg->init;
        hash->update = alg->update;
        hash->final = alg->final;
        hash->finup = alg->finup ?: ahash_def_finup;
        hash->digest = alg->digest;
        hash->export = alg->export;
        hash->import = alg->import;

        if (alg->setkey) {
                hash->setkey = alg->setkey;
                if (!(alg->halg.base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
                        crypto_ahash_set_flags(hash, CRYPTO_TFM_NEED_KEY);
        }

        return 0;
}

static unsigned int crypto_ahash_extsize(struct crypto_alg *alg)
{
        if (alg->cra_type != &crypto_ahash_type)
                return sizeof(struct crypto_shash *);

        return crypto_alg_extsize(alg);
}

#ifdef CONFIG_NET
static int crypto_ahash_report(struct sk_buff *skb, struct crypto_alg *alg)
{
        struct crypto_report_hash rhash;

        strncpy(rhash.type, "ahash", sizeof(rhash.type));

        rhash.blocksize = alg->cra_blocksize;
        rhash.digestsize = __crypto_hash_alg_common(alg)->digestsize;

        if (nla_put(skb, CRYPTOCFGA_REPORT_HASH,
                    sizeof(struct crypto_report_hash), &rhash))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -EMSGSIZE;
}
#else
static int crypto_ahash_report(struct sk_buff *skb, struct crypto_alg *alg)
{
        return -ENOSYS;
}
#endif

static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
        __maybe_unused;
static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
{
        seq_printf(m, "type         : ahash\n");
        seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
                                             "yes" : "no");
        seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
        seq_printf(m, "digestsize   : %u\n",
                   __crypto_hash_alg_common(alg)->digestsize);
}

const struct crypto_type crypto_ahash_type = {
        .extsize = crypto_ahash_extsize,
        .init_tfm = crypto_ahash_init_tfm,
#ifdef CONFIG_PROC_FS
        .show = crypto_ahash_show,
#endif
        .report = crypto_ahash_report,
        .maskclear = ~CRYPTO_ALG_TYPE_MASK,
        .maskset = CRYPTO_ALG_TYPE_AHASH_MASK,
        .type = CRYPTO_ALG_TYPE_AHASH,
        .tfmsize = offsetof(struct crypto_ahash, base),
};
EXPORT_SYMBOL_GPL(crypto_ahash_type);

struct crypto_ahash *crypto_alloc_ahash(const char *alg_name, u32 type,
                                        u32 mask)
{
        return crypto_alloc_tfm(alg_name, &crypto_ahash_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_ahash);

int crypto_has_ahash(const char *alg_name, u32 type, u32 mask)
{
        return crypto_type_has_alg(alg_name, &crypto_ahash_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_has_ahash);

static int ahash_prepare_alg(struct ahash_alg *alg)
{
        struct crypto_alg *base = &alg->halg.base;

        if (alg->halg.digestsize > PAGE_SIZE / 8 ||
            alg->halg.statesize > PAGE_SIZE / 8 ||
            alg->halg.statesize == 0)
                return -EINVAL;

        base->cra_type = &crypto_ahash_type;
        base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
        base->cra_flags |= CRYPTO_ALG_TYPE_AHASH;

        return 0;
}

int crypto_register_ahash(struct ahash_alg *alg)
{
        struct crypto_alg *base = &alg->halg.base;
        int err;

        err = ahash_prepare_alg(alg);
        if (err)
                return err;

        return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_ahash);

int crypto_unregister_ahash(struct ahash_alg *alg)
{
        return crypto_unregister_alg(&alg->halg.base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_ahash);

int crypto_register_ahashes(struct ahash_alg *algs, int count)
{
        int i, ret;

        for (i = 0; i < count; i++) {
                ret = crypto_register_ahash(&algs[i]);
                if (ret)
                        goto err;
        }

        return 0;

err:
        for (--i; i >= 0; --i)
                crypto_unregister_ahash(&algs[i]);

        return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_ahashes);

void crypto_unregister_ahashes(struct ahash_alg *algs, int count)
{
        int i;

        for (i = count - 1; i >= 0; --i)
                crypto_unregister_ahash(&algs[i]);
}
EXPORT_SYMBOL_GPL(crypto_unregister_ahashes);

int ahash_register_instance(struct crypto_template *tmpl,
                            struct ahash_instance *inst)
{
        int err;

        err = ahash_prepare_alg(&inst->alg);
        if (err)
                return err;

        return crypto_register_instance(tmpl, ahash_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(ahash_register_instance);

void ahash_free_instance(struct crypto_instance *inst)
{
        crypto_drop_spawn(crypto_instance_ctx(inst));
        kfree(ahash_instance(inst));
}
EXPORT_SYMBOL_GPL(ahash_free_instance);

int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,
                            struct hash_alg_common *alg,
                            struct crypto_instance *inst)
{
        return crypto_init_spawn2(&spawn->base, &alg->base, inst,
                                  &crypto_ahash_type);
}
EXPORT_SYMBOL_GPL(crypto_init_ahash_spawn);

struct hash_alg_common *ahash_attr_alg(struct rtattr *rta, u32 type, u32 mask)
{
        struct crypto_alg *alg;

        alg = crypto_attr_alg2(rta, &crypto_ahash_type, type, mask);
        return IS_ERR(alg) ? ERR_CAST(alg) : __crypto_hash_alg_common(alg);
}
EXPORT_SYMBOL_GPL(ahash_attr_alg);

bool crypto_hash_alg_has_setkey(struct hash_alg_common *halg)
{
        struct crypto_alg *alg = &halg->base;

        if (alg->cra_type != &crypto_ahash_type)
                return crypto_shash_alg_has_setkey(__crypto_shash_alg(alg));

        return __crypto_ahash_alg(alg)->setkey != NULL;
}
EXPORT_SYMBOL_GPL(crypto_hash_alg_has_setkey);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Asynchronous cryptographic hash type");