/*
 * Symmetric key cipher operations.
 *
 * Generic encrypt/decrypt wrapper for ciphers, handles operations across
 * multiple page boundaries by using temporary blocks.  In user context,
 * the kernel is given a chance to schedule us once per page.
 *
 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * 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/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/bug.h>
#include <linux/cryptouser.h>
#include <linux/compiler.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <linux/seq_file.h>
#include <net/netlink.h>

#include "internal.h"

enum {
        SKCIPHER_WALK_PHYS = 1 << 0,
        SKCIPHER_WALK_SLOW = 1 << 1,
        SKCIPHER_WALK_COPY = 1 << 2,
        SKCIPHER_WALK_DIFF = 1 << 3,
        SKCIPHER_WALK_SLEEP = 1 << 4,
};

struct skcipher_walk_buffer {
        struct list_head entry;
        struct scatter_walk dst;
        unsigned int len;
        u8 *data;
        u8 buffer[];
};

static int skcipher_walk_next(struct skcipher_walk *walk);

static inline void skcipher_unmap(struct scatter_walk *walk, void *vaddr)
{
        if (PageHighMem(scatterwalk_page(walk)))
                kunmap_atomic(vaddr);
}

static inline void *skcipher_map(struct scatter_walk *walk)
{
        struct page *page = scatterwalk_page(walk);

        return (PageHighMem(page) ? kmap_atomic(page) : page_address(page)) +
               offset_in_page(walk->offset);
}

static inline void skcipher_map_src(struct skcipher_walk *walk)
{
        walk->src.virt.addr = skcipher_map(&walk->in);
}

static inline void skcipher_map_dst(struct skcipher_walk *walk)
{
        walk->dst.virt.addr = skcipher_map(&walk->out);
}

static inline void skcipher_unmap_src(struct skcipher_walk *walk)
{
        skcipher_unmap(&walk->in, walk->src.virt.addr);
}

static inline void skcipher_unmap_dst(struct skcipher_walk *walk)
{
        skcipher_unmap(&walk->out, walk->dst.virt.addr);
}

static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
{
        return walk->flags & SKCIPHER_WALK_SLEEP ? GFP_KERNEL : GFP_ATOMIC;
}

/* Get a spot of the specified length that does not straddle a page.
 * The caller needs to ensure that there is enough space for this operation.
 */
static inline u8 *skcipher_get_spot(u8 *start, unsigned int len)
{
        u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);

        return max(start, end_page);
}

static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
{
        u8 *addr;

        addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
        addr = skcipher_get_spot(addr, bsize);
        scatterwalk_copychunks(addr, &walk->out, bsize,
                               (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1);
}

int skcipher_walk_done(struct skcipher_walk *walk, int err)
{
        unsigned int n; /* bytes processed */
        bool more;

        if (unlikely(err < 0))
                goto finish;

        n = walk->nbytes - err;
        walk->total -= n;
        more = (walk->total != 0);

        if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS |
                                    SKCIPHER_WALK_SLOW |
                                    SKCIPHER_WALK_COPY |
                                    SKCIPHER_WALK_DIFF)))) {
unmap_src:
                skcipher_unmap_src(walk);
        } else if (walk->flags & SKCIPHER_WALK_DIFF) {
                skcipher_unmap_dst(walk);
                goto unmap_src;
        } else if (walk->flags & SKCIPHER_WALK_COPY) {
                skcipher_map_dst(walk);
                memcpy(walk->dst.virt.addr, walk->page, n);
                skcipher_unmap_dst(walk);
        } else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) {
                if (WARN_ON(err)) {
                        /* unexpected case; didn't process all bytes */
                        err = -EINVAL;
                        goto finish;
                }
                skcipher_done_slow(walk, n);
                goto already_advanced;
        }

        scatterwalk_advance(&walk->in, n);
        scatterwalk_advance(&walk->out, n);
already_advanced:
        scatterwalk_done(&walk->in, 0, more);
        scatterwalk_done(&walk->out, 1, more);

        if (more) {
                crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ?
                             CRYPTO_TFM_REQ_MAY_SLEEP : 0);
                return skcipher_walk_next(walk);
        }
        err = 0;
finish:
        walk->nbytes = 0;

        /* Short-circuit for the common/fast path. */
        if (!((unsigned long)walk->buffer | (unsigned long)walk->page))
                goto out;

        if (walk->flags & SKCIPHER_WALK_PHYS)
                goto out;

        if (walk->iv != walk->oiv)
                memcpy(walk->oiv, walk->iv, walk->ivsize);
        if (walk->buffer != walk->page)
                kfree(walk->buffer);
        if (walk->page)
                free_page((unsigned long)walk->page);

out:
        return err;
}
EXPORT_SYMBOL_GPL(skcipher_walk_done);

void skcipher_walk_complete(struct skcipher_walk *walk, int err)
{
        struct skcipher_walk_buffer *p, *tmp;

        list_for_each_entry_safe(p, tmp, &walk->buffers, entry) {
                u8 *data;

                if (err)
                        goto done;

                data = p->data;
                if (!data) {
                        data = PTR_ALIGN(&p->buffer[0], walk->alignmask + 1);
                        data = skcipher_get_spot(data, walk->stride);
                }

                scatterwalk_copychunks(data, &p->dst, p->len, 1);

                if (offset_in_page(p->data) + p->len + walk->stride >
                    PAGE_SIZE)
                        free_page((unsigned long)p->data);

done:
                list_del(&p->entry);
                kfree(p);
        }

        if (!err && walk->iv != walk->oiv)
                memcpy(walk->oiv, walk->iv, walk->ivsize);
        if (walk->buffer != walk->page)
                kfree(walk->buffer);
        if (walk->page)
                free_page((unsigned long)walk->page);
}
EXPORT_SYMBOL_GPL(skcipher_walk_complete);

static void skcipher_queue_write(struct skcipher_walk *walk,
                                 struct skcipher_walk_buffer *p)
{
        p->dst = walk->out;
        list_add_tail(&p->entry, &walk->buffers);
}

static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
{
        bool phys = walk->flags & SKCIPHER_WALK_PHYS;
        unsigned alignmask = walk->alignmask;
        struct skcipher_walk_buffer *p;
        unsigned a;
        unsigned n;
        u8 *buffer;
        void *v;

        if (!phys) {
                if (!walk->buffer)
                        walk->buffer = walk->page;
                buffer = walk->buffer;
                if (buffer)
                        goto ok;
        }

        /* Start with the minimum alignment of kmalloc. */
        a = crypto_tfm_ctx_alignment() - 1;
        n = bsize;

        if (phys) {
                /* Calculate the minimum alignment of p->buffer. */
                a &= (sizeof(*p) ^ (sizeof(*p) - 1)) >> 1;
                n += sizeof(*p);
        }

        /* Minimum size to align p->buffer by alignmask. */
        n += alignmask & ~a;

        /* Minimum size to ensure p->buffer does not straddle a page. */
        n += (bsize - 1) & ~(alignmask | a);

        v = kzalloc(n, skcipher_walk_gfp(walk));
        if (!v)
                return skcipher_walk_done(walk, -ENOMEM);

        if (phys) {
                p = v;
                p->len = bsize;
                skcipher_queue_write(walk, p);
                buffer = p->buffer;
        } else {
                walk->buffer = v;
                buffer = v;
        }

ok:
        walk->dst.virt.addr = PTR_ALIGN(buffer, alignmask + 1);
        walk->dst.virt.addr = skcipher_get_spot(walk->dst.virt.addr, bsize);
        walk->src.virt.addr = walk->dst.virt.addr;

        scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);

        walk->nbytes = bsize;
        walk->flags |= SKCIPHER_WALK_SLOW;

        return 0;
}

static int skcipher_next_copy(struct skcipher_walk *walk)
{
        struct skcipher_walk_buffer *p;
        u8 *tmp = walk->page;

        skcipher_map_src(walk);
        memcpy(tmp, walk->src.virt.addr, walk->nbytes);
        skcipher_unmap_src(walk);

        walk->src.virt.addr = tmp;
        walk->dst.virt.addr = tmp;

        if (!(walk->flags & SKCIPHER_WALK_PHYS))
                return 0;

        p = kmalloc(sizeof(*p), skcipher_walk_gfp(walk));
        if (!p)
                return -ENOMEM;

        p->data = walk->page;
        p->len = walk->nbytes;
        skcipher_queue_write(walk, p);

        if (offset_in_page(walk->page) + walk->nbytes + walk->stride >
            PAGE_SIZE)
                walk->page = NULL;
        else
                walk->page += walk->nbytes;

        return 0;
}

static int skcipher_next_fast(struct skcipher_walk *walk)
{
        unsigned long diff;

        walk->src.phys.page = scatterwalk_page(&walk->in);
        walk->src.phys.offset = offset_in_page(walk->in.offset);
        walk->dst.phys.page = scatterwalk_page(&walk->out);
        walk->dst.phys.offset = offset_in_page(walk->out.offset);

        if (walk->flags & SKCIPHER_WALK_PHYS)
                return 0;

        diff = walk->src.phys.offset - walk->dst.phys.offset;
        diff |= walk->src.virt.page - walk->dst.virt.page;

        skcipher_map_src(walk);
        walk->dst.virt.addr = walk->src.virt.addr;

        if (diff) {
                walk->flags |= SKCIPHER_WALK_DIFF;
                skcipher_map_dst(walk);
        }

        return 0;
}

static int skcipher_walk_next(struct skcipher_walk *walk)
{
        unsigned int bsize;
        unsigned int n;
        int err;

        walk->flags &= ~(SKCIPHER_WALK_SLOW | SKCIPHER_WALK_COPY |
                         SKCIPHER_WALK_DIFF);

        n = walk->total;
        bsize = min(walk->stride, max(n, walk->blocksize));
        n = scatterwalk_clamp(&walk->in, n);
        n = scatterwalk_clamp(&walk->out, n);

        if (unlikely(n < bsize)) {
                if (unlikely(walk->total < walk->blocksize))
                        return skcipher_walk_done(walk, -EINVAL);

slow_path:
                err = skcipher_next_slow(walk, bsize);
                goto set_phys_lowmem;
        }

        if (unlikely((walk->in.offset | walk->out.offset) & walk->alignmask)) {
                if (!walk->page) {
                        gfp_t gfp = skcipher_walk_gfp(walk);

                        walk->page = (void *)__get_free_page(gfp);
                        if (!walk->page)
                                goto slow_path;
                }

                walk->nbytes = min_t(unsigned, n,
                                     PAGE_SIZE - offset_in_page(walk->page));
                walk->flags |= SKCIPHER_WALK_COPY;
                err = skcipher_next_copy(walk);
                goto set_phys_lowmem;
        }

        walk->nbytes = n;

        return skcipher_next_fast(walk);

set_phys_lowmem:
        if (!err && (walk->flags & SKCIPHER_WALK_PHYS)) {
                walk->src.phys.page = virt_to_page(walk->src.virt.addr);
                walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
                walk->src.phys.offset &= PAGE_SIZE - 1;
                walk->dst.phys.offset &= PAGE_SIZE - 1;
        }
        return err;
}

static int skcipher_copy_iv(struct skcipher_walk *walk)
{
        unsigned a = crypto_tfm_ctx_alignment() - 1;
        unsigned alignmask = walk->alignmask;
        unsigned ivsize = walk->ivsize;
        unsigned bs = walk->stride;
        unsigned aligned_bs;
        unsigned size;
        u8 *iv;

        aligned_bs = ALIGN(bs, alignmask);

        /* Minimum size to align buffer by alignmask. */
        size = alignmask & ~a;

        if (walk->flags & SKCIPHER_WALK_PHYS)
                size += ivsize;
        else {
                size += aligned_bs + ivsize;

                /* Minimum size to ensure buffer does not straddle a page. */
                size += (bs - 1) & ~(alignmask | a);
        }

        walk->buffer = kmalloc(size, skcipher_walk_gfp(walk));
        if (!walk->buffer)
                return -ENOMEM;

        iv = PTR_ALIGN(walk->buffer, alignmask + 1);
        iv = skcipher_get_spot(iv, bs) + aligned_bs;

        walk->iv = memcpy(iv, walk->iv, walk->ivsize);
        return 0;
}

static int skcipher_walk_first(struct skcipher_walk *walk)
{
        if (WARN_ON_ONCE(in_irq()))
                return -EDEADLK;

        walk->buffer = NULL;
        if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
                int err = skcipher_copy_iv(walk);
                if (err)
                        return err;
        }

        walk->page = NULL;
        walk->nbytes = walk->total;

        return skcipher_walk_next(walk);
}

static int skcipher_walk_skcipher(struct skcipher_walk *walk,
                                  struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

        walk->total = req->cryptlen;
        walk->nbytes = 0;
        walk->iv = req->iv;
        walk->oiv = req->iv;

        if (unlikely(!walk->total))
                return 0;

        scatterwalk_start(&walk->in, req->src);
        scatterwalk_start(&walk->out, req->dst);

        walk->flags &= ~SKCIPHER_WALK_SLEEP;
        walk->flags |= req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ?
                       SKCIPHER_WALK_SLEEP : 0;

        walk->blocksize = crypto_skcipher_blocksize(tfm);
        walk->stride = crypto_skcipher_walksize(tfm);
        walk->ivsize = crypto_skcipher_ivsize(tfm);
        walk->alignmask = crypto_skcipher_alignmask(tfm);

        return skcipher_walk_first(walk);
}

int skcipher_walk_virt(struct skcipher_walk *walk,
                       struct skcipher_request *req, bool atomic)
{
        int err;

        walk->flags &= ~SKCIPHER_WALK_PHYS;

        err = skcipher_walk_skcipher(walk, req);

        walk->flags &= atomic ? ~SKCIPHER_WALK_SLEEP : ~0;

        return err;
}
EXPORT_SYMBOL_GPL(skcipher_walk_virt);

void skcipher_walk_atomise(struct skcipher_walk *walk)
{
        walk->flags &= ~SKCIPHER_WALK_SLEEP;
}
EXPORT_SYMBOL_GPL(skcipher_walk_atomise);

int skcipher_walk_async(struct skcipher_walk *walk,
                        struct skcipher_request *req)
{
        walk->flags |= SKCIPHER_WALK_PHYS;

        INIT_LIST_HEAD(&walk->buffers);

        return skcipher_walk_skcipher(walk, req);
}
EXPORT_SYMBOL_GPL(skcipher_walk_async);

static int skcipher_walk_aead_common(struct skcipher_walk *walk,
                                     struct aead_request *req, bool atomic)
{
        struct crypto_aead *tfm = crypto_aead_reqtfm(req);
        int err;

        walk->nbytes = 0;
        walk->iv = req->iv;
        walk->oiv = req->iv;

        if (unlikely(!walk->total))
                return 0;

        walk->flags &= ~SKCIPHER_WALK_PHYS;

        scatterwalk_start(&walk->in, req->src);
        scatterwalk_start(&walk->out, req->dst);

        scatterwalk_copychunks(NULL, &walk->in, req->assoclen, 2);
        scatterwalk_copychunks(NULL, &walk->out, req->assoclen, 2);

        scatterwalk_done(&walk->in, 0, walk->total);
        scatterwalk_done(&walk->out, 0, walk->total);

        if (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP)
                walk->flags |= SKCIPHER_WALK_SLEEP;
        else
                walk->flags &= ~SKCIPHER_WALK_SLEEP;

        walk->blocksize = crypto_aead_blocksize(tfm);
        walk->stride = crypto_aead_chunksize(tfm);
        walk->ivsize = crypto_aead_ivsize(tfm);
        walk->alignmask = crypto_aead_alignmask(tfm);

        err = skcipher_walk_first(walk);

        if (atomic)
                walk->flags &= ~SKCIPHER_WALK_SLEEP;

        return err;
}

int skcipher_walk_aead(struct skcipher_walk *walk, struct aead_request *req,
                       bool atomic)
{
        walk->total = req->cryptlen;

        return skcipher_walk_aead_common(walk, req, atomic);
}
EXPORT_SYMBOL_GPL(skcipher_walk_aead);

int skcipher_walk_aead_encrypt(struct skcipher_walk *walk,
                               struct aead_request *req, bool atomic)
{
        walk->total = req->cryptlen;

        return skcipher_walk_aead_common(walk, req, atomic);
}
EXPORT_SYMBOL_GPL(skcipher_walk_aead_encrypt);

int skcipher_walk_aead_decrypt(struct skcipher_walk *walk,
                               struct aead_request *req, bool atomic)
{
        struct crypto_aead *tfm = crypto_aead_reqtfm(req);

        walk->total = req->cryptlen - crypto_aead_authsize(tfm);

        return skcipher_walk_aead_common(walk, req, atomic);
}
EXPORT_SYMBOL_GPL(skcipher_walk_aead_decrypt);

static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
{
        if (alg->cra_type == &crypto_blkcipher_type)
                return sizeof(struct crypto_blkcipher *);

        if (alg->cra_type == &crypto_ablkcipher_type ||
            alg->cra_type == &crypto_givcipher_type)
                return sizeof(struct crypto_ablkcipher *);

        return crypto_alg_extsize(alg);
}

static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
                                     const u8 *key, unsigned int keylen)
{
        struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
        struct crypto_blkcipher *blkcipher = *ctx;
        int err;

        crypto_blkcipher_clear_flags(blkcipher, ~0);
        crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
                                              CRYPTO_TFM_REQ_MASK);
        err = crypto_blkcipher_setkey(blkcipher, key, keylen);
        crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
                                       CRYPTO_TFM_RES_MASK);
        if (err)
                return err;

        crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
        return 0;
}

static int skcipher_crypt_blkcipher(struct skcipher_request *req,
                                    int (*crypt)(struct blkcipher_desc *,
                                                 struct scatterlist *,
                                                 struct scatterlist *,
                                                 unsigned int))
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
        struct blkcipher_desc desc = {
                .tfm = *ctx,
                .info = req->iv,
                .flags = req->base.flags,
        };


        return crypt(&desc, req->dst, req->src, req->cryptlen);
}

static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
{
        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        return skcipher_crypt_blkcipher(req, alg->encrypt);
}

static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
{
        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        return skcipher_crypt_blkcipher(req, alg->decrypt);
}

static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
{
        struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);

        crypto_free_blkcipher(*ctx);
}

static int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
{
        struct crypto_alg *calg = tfm->__crt_alg;
        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
        struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
        struct crypto_blkcipher *blkcipher;
        struct crypto_tfm *btfm;

        if (!crypto_mod_get(calg))
                return -EAGAIN;

        btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
                                        CRYPTO_ALG_TYPE_MASK);
        if (IS_ERR(btfm)) {
                crypto_mod_put(calg);
                return PTR_ERR(btfm);
        }

        blkcipher = __crypto_blkcipher_cast(btfm);
        *ctx = blkcipher;
        tfm->exit = crypto_exit_skcipher_ops_blkcipher;

        skcipher->setkey = skcipher_setkey_blkcipher;
        skcipher->encrypt = skcipher_encrypt_blkcipher;
        skcipher->decrypt = skcipher_decrypt_blkcipher;

        skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
        skcipher->keysize = calg->cra_blkcipher.max_keysize;

        if (skcipher->keysize)
                crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);

        return 0;
}

static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
                                      const u8 *key, unsigned int keylen)
{
        struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
        struct crypto_ablkcipher *ablkcipher = *ctx;
        int err;

        crypto_ablkcipher_clear_flags(ablkcipher, ~0);
        crypto_ablkcipher_set_flags(ablkcipher,
                                    crypto_skcipher_get_flags(tfm) &
                                    CRYPTO_TFM_REQ_MASK);
        err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
        crypto_skcipher_set_flags(tfm,
                                  crypto_ablkcipher_get_flags(ablkcipher) &
                                  CRYPTO_TFM_RES_MASK);
        if (err)
                return err;

        crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
        return 0;
}

static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
                                     int (*crypt)(struct ablkcipher_request *))
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
        struct ablkcipher_request *subreq = skcipher_request_ctx(req);

        ablkcipher_request_set_tfm(subreq, *ctx);
        ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
                                        req->base.complete, req->base.data);
        ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
                                     req->iv);

        return crypt(subreq);
}

static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
{
        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
        struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

        return skcipher_crypt_ablkcipher(req, alg->encrypt);
}

static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
{
        struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
        struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
        struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

        return skcipher_crypt_ablkcipher(req, alg->decrypt);
}

static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
{
        struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);

        crypto_free_ablkcipher(*ctx);
}

static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
{
        struct crypto_alg *calg = tfm->__crt_alg;
        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
        struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
        struct crypto_ablkcipher *ablkcipher;
        struct crypto_tfm *abtfm;

        if (!crypto_mod_get(calg))
                return -EAGAIN;

        abtfm = __crypto_alloc_tfm(calg, 0, 0);
        if (IS_ERR(abtfm)) {
                crypto_mod_put(calg);
                return PTR_ERR(abtfm);
        }

        ablkcipher = __crypto_ablkcipher_cast(abtfm);
        *ctx = ablkcipher;
        tfm->exit = crypto_exit_skcipher_ops_ablkcipher;

        skcipher->setkey = skcipher_setkey_ablkcipher;
        skcipher->encrypt = skcipher_encrypt_ablkcipher;
        skcipher->decrypt = skcipher_decrypt_ablkcipher;

        skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
        skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
                            sizeof(struct ablkcipher_request);
        skcipher->keysize = calg->cra_ablkcipher.max_keysize;

        if (skcipher->keysize)
                crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);

        return 0;
}

static int skcipher_setkey_unaligned(struct crypto_skcipher *tfm,
                                     const u8 *key, unsigned int keylen)
{
        unsigned long alignmask = crypto_skcipher_alignmask(tfm);
        struct skcipher_alg *cipher = crypto_skcipher_alg(tfm);
        u8 *buffer, *alignbuffer;
        unsigned long absize;
        int ret;

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

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

static int skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
                           unsigned int keylen)
{
        struct skcipher_alg *cipher = crypto_skcipher_alg(tfm);
        unsigned long alignmask = crypto_skcipher_alignmask(tfm);
        int err;

        if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
                crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
                return -EINVAL;
        }

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

        if (err)
                return err;

        crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
        return 0;
}

static void crypto_skcipher_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
        struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

        alg->exit(skcipher);
}

static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
        struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

        if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
                return crypto_init_skcipher_ops_blkcipher(tfm);

        if (tfm->__crt_alg->cra_type == &crypto_ablkcipher_type ||
            tfm->__crt_alg->cra_type == &crypto_givcipher_type)
                return crypto_init_skcipher_ops_ablkcipher(tfm);

        skcipher->setkey = skcipher_setkey;
        skcipher->encrypt = alg->encrypt;
        skcipher->decrypt = alg->decrypt;
        skcipher->ivsize = alg->ivsize;
        skcipher->keysize = alg->max_keysize;

        if (skcipher->keysize)
                crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);

        if (alg->exit)
                skcipher->base.exit = crypto_skcipher_exit_tfm;

        if (alg->init)
                return alg->init(skcipher);

        return 0;
}

static void crypto_skcipher_free_instance(struct crypto_instance *inst)
{
        struct skcipher_instance *skcipher =
                container_of(inst, struct skcipher_instance, s.base);

        skcipher->free(skcipher);
}

static void crypto_skcipher_show(struct seq_file *m, struct crypto_alg *alg)
        __maybe_unused;
static void crypto_skcipher_show(struct seq_file *m, struct crypto_alg *alg)
{
        struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
                                                     base);

        seq_printf(m, "type         : skcipher\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, "min keysize  : %u\n", skcipher->min_keysize);
        seq_printf(m, "max keysize  : %u\n", skcipher->max_keysize);
        seq_printf(m, "ivsize       : %u\n", skcipher->ivsize);
        seq_printf(m, "chunksize    : %u\n", skcipher->chunksize);
        seq_printf(m, "walksize     : %u\n", skcipher->walksize);
}

#ifdef CONFIG_NET
static int crypto_skcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
        struct crypto_report_blkcipher rblkcipher;
        struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
                                                     base);

        strncpy(rblkcipher.type, "skcipher", sizeof(rblkcipher.type));
        strncpy(rblkcipher.geniv, "<none>", sizeof(rblkcipher.geniv));

        rblkcipher.blocksize = alg->cra_blocksize;
        rblkcipher.min_keysize = skcipher->min_keysize;
        rblkcipher.max_keysize = skcipher->max_keysize;
        rblkcipher.ivsize = skcipher->ivsize;

        if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
                    sizeof(struct crypto_report_blkcipher), &rblkcipher))
                goto nla_put_failure;
        return 0;

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

static const struct crypto_type crypto_skcipher_type2 = {
        .extsize = crypto_skcipher_extsize,
        .init_tfm = crypto_skcipher_init_tfm,
        .free = crypto_skcipher_free_instance,
#ifdef CONFIG_PROC_FS
        .show = crypto_skcipher_show,
#endif
        .report = crypto_skcipher_report,
        .maskclear = ~CRYPTO_ALG_TYPE_MASK,
        .maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
        .type = CRYPTO_ALG_TYPE_SKCIPHER,
        .tfmsize = offsetof(struct crypto_skcipher, base),
};

int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn,
                          const char *name, u32 type, u32 mask)
{
        spawn->base.frontend = &crypto_skcipher_type2;
        return crypto_grab_spawn(&spawn->base, name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
                                              u32 type, u32 mask)
{
        return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);

struct crypto_sync_skcipher *crypto_alloc_sync_skcipher(
                                const char *alg_name, u32 type, u32 mask)
{
        struct crypto_skcipher *tfm;

        /* Only sync algorithms allowed. */
        mask |= CRYPTO_ALG_ASYNC;

        tfm = crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);

        /*
         * Make sure we do not allocate something that might get used with
         * an on-stack request: check the request size.
         */
        if (!IS_ERR(tfm) && WARN_ON(crypto_skcipher_reqsize(tfm) >
                                    MAX_SYNC_SKCIPHER_REQSIZE)) {
                crypto_free_skcipher(tfm);
                return ERR_PTR(-EINVAL);
        }

        return (struct crypto_sync_skcipher *)tfm;
}
EXPORT_SYMBOL_GPL(crypto_alloc_sync_skcipher);

int crypto_has_skcipher2(const char *alg_name, u32 type, u32 mask)
{
        return crypto_type_has_alg(alg_name, &crypto_skcipher_type2,
                                   type, mask);
}
EXPORT_SYMBOL_GPL(crypto_has_skcipher2);

static int skcipher_prepare_alg(struct skcipher_alg *alg)
{
        struct crypto_alg *base = &alg->base;

        if (alg->ivsize > PAGE_SIZE / 8 || alg->chunksize > PAGE_SIZE / 8 ||
            alg->walksize > PAGE_SIZE / 8)
                return -EINVAL;

        if (!alg->chunksize)
                alg->chunksize = base->cra_blocksize;
        if (!alg->walksize)
                alg->walksize = alg->chunksize;

        base->cra_type = &crypto_skcipher_type2;
        base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
        base->cra_flags |= CRYPTO_ALG_TYPE_SKCIPHER;

        return 0;
}

int crypto_register_skcipher(struct skcipher_alg *alg)
{
        struct crypto_alg *base = &alg->base;
        int err;

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

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

void crypto_unregister_skcipher(struct skcipher_alg *alg)
{
        crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_skcipher);

int crypto_register_skciphers(struct skcipher_alg *algs, int count)
{
        int i, ret;

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

        return 0;

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

        return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_skciphers);

void crypto_unregister_skciphers(struct skcipher_alg *algs, int count)
{
        int i;

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

int skcipher_register_instance(struct crypto_template *tmpl,
                           struct skcipher_instance *inst)
{
        int err;

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

        return crypto_register_instance(tmpl, skcipher_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(skcipher_register_instance);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Symmetric key cipher type");