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/*

 * Block chaining 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) 2006 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 <linux/crypto.h>

#include <linux/errno.h>

#include <linux/hardirq.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/scatterlist.h>

#include <linux/seq_file.h>

#include <linux/slab.h>

#include <linux/string.h>

#include "internal.h"

#include "scatterwalk.h"

enum {

        BLKCIPHER_WALK_PHYS = 1 << 0,

        BLKCIPHER_WALK_SLOW = 1 << 1,

        BLKCIPHER_WALK_COPY = 1 << 2,

        BLKCIPHER_WALK_DIFF = 1 << 3,

};

static int blkcipher_walk_next(struct blkcipher_desc *desc,

                               struct blkcipher_walk *walk);

static int blkcipher_walk_first(struct blkcipher_desc *desc,

                                struct blkcipher_walk *walk);

static inline void blkcipher_map_src(struct blkcipher_walk *walk)

{

        walk->src.virt.addr = scatterwalk_map(&walk->in, 0);

}

static inline void blkcipher_map_dst(struct blkcipher_walk *walk)

{

        walk->dst.virt.addr = scatterwalk_map(&walk->out, 1);

}

static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)

{

        scatterwalk_unmap(walk->src.virt.addr, 0);

}

static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)

{

        scatterwalk_unmap(walk->dst.virt.addr, 1);

}

/* 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 *blkcipher_get_spot(u8 *start, unsigned int len)

{

        u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);

        return max(start, end_page);

}

static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm,

                                               struct blkcipher_walk *walk,

                                               unsigned int bsize)

{

        u8 *addr;

        unsigned int alignmask = crypto_blkcipher_alignmask(tfm);

        addr = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);

        addr = blkcipher_get_spot(addr, bsize);

        scatterwalk_copychunks(addr, &walk->out, bsize, 1);

        return bsize;

}

static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,

                                               unsigned int n)

{

        if (walk->flags & BLKCIPHER_WALK_COPY) {

                blkcipher_map_dst(walk);

                memcpy(walk->dst.virt.addr, walk->page, n);

                blkcipher_unmap_dst(walk);

        } else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {

                blkcipher_unmap_src(walk);

                if (walk->flags & BLKCIPHER_WALK_DIFF)

                        blkcipher_unmap_dst(walk);

        }

        scatterwalk_advance(&walk->in, n);

        scatterwalk_advance(&walk->out, n);

        return n;

}

int blkcipher_walk_done(struct blkcipher_desc *desc,

                        struct blkcipher_walk *walk, int err)

{

        struct crypto_blkcipher *tfm = desc->tfm;

        unsigned int nbytes = 0;

        if (likely(err >= 0)) {

                unsigned int n = walk->nbytes - err;

                if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))

                        n = blkcipher_done_fast(walk, n);

                else if (WARN_ON(err)) {

                        err = -EINVAL;

                        goto err;

                } else

                        n = blkcipher_done_slow(tfm, walk, n);

                nbytes = walk->total - n;

                err = 0;

        }

        scatterwalk_done(&walk->in, 0, nbytes);

        scatterwalk_done(&walk->out, 1, nbytes);

        walk->total = nbytes;

        walk->nbytes = nbytes;

        if (nbytes) {

                crypto_yield(desc->flags);

                return blkcipher_walk_next(desc, walk);

        }

err:

        if (walk->iv != desc->info)

                memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));

        if (walk->buffer != walk->page)

                kfree(walk->buffer);

        if (walk->page)

                free_page((unsigned long)walk->page);

        return err;

}

EXPORT_SYMBOL_GPL(blkcipher_walk_done);

static inline int blkcipher_next_slow(struct blkcipher_desc *desc,

                                      struct blkcipher_walk *walk,

                                      unsigned int bsize,

                                      unsigned int alignmask)

{

        unsigned int n;

        unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);

        if (walk->buffer)

                goto ok;

        walk->buffer = walk->page;

        if (walk->buffer)

                goto ok;

        n = aligned_bsize * 3 - (alignmask + 1) +

            (alignmask & ~(crypto_tfm_ctx_alignment() - 1));

        walk->buffer = kmalloc(n, GFP_ATOMIC);

        if (!walk->buffer)

                return blkcipher_walk_done(desc, walk, -ENOMEM);

ok:

        walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,

                                          alignmask + 1);

        walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);

        walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr +

                                                 aligned_bsize, bsize);

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

        walk->nbytes = bsize;

        walk->flags |= BLKCIPHER_WALK_SLOW;

        return 0;

}

static inline int blkcipher_next_copy(struct blkcipher_walk *walk)

{

        u8 *tmp = walk->page;

        blkcipher_map_src(walk);

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

        blkcipher_unmap_src(walk);

        walk->src.virt.addr = tmp;

        walk->dst.virt.addr = tmp;

        return 0;

}

static inline int blkcipher_next_fast(struct blkcipher_desc *desc,

                                      struct blkcipher_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 & BLKCIPHER_WALK_PHYS)

                return 0;

        diff = walk->src.phys.offset - walk->dst.phys.offset;

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

        blkcipher_map_src(walk);

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

        if (diff) {

                walk->flags |= BLKCIPHER_WALK_DIFF;

                blkcipher_map_dst(walk);

        }

        return 0;

}

static int blkcipher_walk_next(struct blkcipher_desc *desc,

                               struct blkcipher_walk *walk)

{

        struct crypto_blkcipher *tfm = desc->tfm;

        unsigned int alignmask = crypto_blkcipher_alignmask(tfm);

        unsigned int bsize;

        unsigned int n;

        int err;

        n = walk->total;

        if (unlikely(n < crypto_blkcipher_blocksize(tfm))) {

                desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;

                return blkcipher_walk_done(desc, walk, -EINVAL);

        }

        walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |

                         BLKCIPHER_WALK_DIFF);

        if (!scatterwalk_aligned(&walk->in, alignmask) ||

            !scatterwalk_aligned(&walk->out, alignmask)) {

                walk->flags |= BLKCIPHER_WALK_COPY;

                if (!walk->page) {

                        walk->page = (void *)__get_free_page(GFP_ATOMIC);

                        if (!walk->page)

                                n = 0;

                }

        }

        bsize = min(walk->blocksize, n);

        n = scatterwalk_clamp(&walk->in, n);

        n = scatterwalk_clamp(&walk->out, n);

        if (unlikely(n < bsize)) {

                err = blkcipher_next_slow(desc, walk, bsize, alignmask);

                goto set_phys_lowmem;

        }

        walk->nbytes = n;

        if (walk->flags & BLKCIPHER_WALK_COPY) {

                err = blkcipher_next_copy(walk);

                goto set_phys_lowmem;

        }

        return blkcipher_next_fast(desc, walk);

set_phys_lowmem:

        if (walk->flags & BLKCIPHER_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 inline int blkcipher_copy_iv(struct blkcipher_walk *walk,

                                    struct crypto_blkcipher *tfm,

                                    unsigned int alignmask)

{

        unsigned bs = walk->blocksize;

        unsigned int ivsize = crypto_blkcipher_ivsize(tfm);

        unsigned aligned_bs = ALIGN(bs, alignmask + 1);

        unsigned int size = aligned_bs * 2 + ivsize + max(aligned_bs, ivsize) -

                            (alignmask + 1);

        u8 *iv;

        size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);

        walk->buffer = kmalloc(size, GFP_ATOMIC);

        if (!walk->buffer)

                return -ENOMEM;

        iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);

        iv = blkcipher_get_spot(iv, bs) + aligned_bs;

        iv = blkcipher_get_spot(iv, bs) + aligned_bs;

        iv = blkcipher_get_spot(iv, ivsize);

        walk->iv = memcpy(iv, walk->iv, ivsize);

        return 0;

}

int blkcipher_walk_virt(struct blkcipher_desc *desc,

                        struct blkcipher_walk *walk)

{

        walk->flags &= ~BLKCIPHER_WALK_PHYS;

        walk->blocksize = crypto_blkcipher_blocksize(desc->tfm);

        return blkcipher_walk_first(desc, walk);

}

EXPORT_SYMBOL_GPL(blkcipher_walk_virt);

int blkcipher_walk_phys(struct blkcipher_desc *desc,

                        struct blkcipher_walk *walk)

{

        walk->flags |= BLKCIPHER_WALK_PHYS;

        walk->blocksize = crypto_blkcipher_blocksize(desc->tfm);

        return blkcipher_walk_first(desc, walk);

}

EXPORT_SYMBOL_GPL(blkcipher_walk_phys);

static int blkcipher_walk_first(struct blkcipher_desc *desc,

                                struct blkcipher_walk *walk)

{

        struct crypto_blkcipher *tfm = desc->tfm;

        unsigned int alignmask = crypto_blkcipher_alignmask(tfm);

        if (WARN_ON_ONCE(in_irq()))

                return -EDEADLK;

        walk->nbytes = walk->total;

        if (unlikely(!walk->total))

                return 0;

        walk->buffer = NULL;

        walk->iv = desc->info;

        if (unlikely(((unsigned long)walk->iv & alignmask))) {

                int err = blkcipher_copy_iv(walk, tfm, alignmask);

                if (err)

                        return err;

        }

        scatterwalk_start(&walk->in, walk->in.sg);

        scatterwalk_start(&walk->out, walk->out.sg);

        walk->page = NULL;

        return blkcipher_walk_next(desc, walk);

}

int blkcipher_walk_virt_block(struct blkcipher_desc *desc,

                              struct blkcipher_walk *walk,

                              unsigned int blocksize)

{

        walk->flags &= ~BLKCIPHER_WALK_PHYS;

        walk->blocksize = blocksize;

        return blkcipher_walk_first(desc, walk);

}

EXPORT_SYMBOL_GPL(blkcipher_walk_virt_block);

static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,

                            unsigned int keylen)

{

        struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;

        unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);

        int ret;

        u8 *buffer, *alignbuffer;

        unsigned long absize;

        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);

        memset(alignbuffer, 0, keylen);

        kfree(buffer);

        return ret;

}

static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)

{

        struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;

        unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);

        if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {

                tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;

                return -EINVAL;

        }

        if ((unsigned long)key & alignmask)

                return setkey_unaligned(tfm, key, keylen);

        return cipher->setkey(tfm, key, keylen);

}

static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,

                        unsigned int keylen)

{

        return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);

}

static int async_encrypt(struct ablkcipher_request *req)

{

        struct crypto_tfm *tfm = req->base.tfm;

        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        struct blkcipher_desc desc = {

                .tfm = __crypto_blkcipher_cast(tfm),

                .info = req->info,

                .flags = req->base.flags,

        };

        return alg->encrypt(&desc, req->dst, req->src, req->nbytes);

}

static int async_decrypt(struct ablkcipher_request *req)

{

        struct crypto_tfm *tfm = req->base.tfm;

        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        struct blkcipher_desc desc = {

                .tfm = __crypto_blkcipher_cast(tfm),

                .info = req->info,

                .flags = req->base.flags,

        };

        return alg->decrypt(&desc, req->dst, req->src, req->nbytes);

}

static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,

                                             u32 mask)

{

        struct blkcipher_alg *cipher = &alg->cra_blkcipher;

        unsigned int len = alg->cra_ctxsize;

        type ^= CRYPTO_ALG_ASYNC;

        mask &= CRYPTO_ALG_ASYNC;

        if ((type & mask) && cipher->ivsize) {

                len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);

                len += cipher->ivsize;

        }

        return len;

}

static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)

{

        struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;

        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        crt->setkey = async_setkey;

        crt->encrypt = async_encrypt;

        crt->decrypt = async_decrypt;

        crt->ivsize = alg->ivsize;

        return 0;

}

static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)

{

        struct blkcipher_tfm *crt = &tfm->crt_blkcipher;

        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;

        unsigned long addr;

        crt->setkey = setkey;

        crt->encrypt = alg->encrypt;

        crt->decrypt = alg->decrypt;

        addr = (unsigned long)crypto_tfm_ctx(tfm);

        addr = ALIGN(addr, align);

        addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);

        crt->iv = (void *)addr;

        return 0;

}

static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)

{

        struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

        if (alg->ivsize > PAGE_SIZE / 8)

                return -EINVAL;

        type ^= CRYPTO_ALG_ASYNC;

        mask &= CRYPTO_ALG_ASYNC;

        if (type & mask)

                return crypto_init_blkcipher_ops_sync(tfm);

        else

                return crypto_init_blkcipher_ops_async(tfm);

}

static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)

        __attribute__ ((unused));

static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)

{

        seq_printf(m, "type         : blkcipher\n");

        seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);

        seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);

        seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);

        seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);

}

const struct crypto_type crypto_blkcipher_type = {

        .ctxsize = crypto_blkcipher_ctxsize,

        .init = crypto_init_blkcipher_ops,

#ifdef CONFIG_PROC_FS

        .show = crypto_blkcipher_show,

#endif

};

EXPORT_SYMBOL_GPL(crypto_blkcipher_type);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Generic block chaining cipher type");