1 files changed, 264 insertions, 0 deletions

diff --git a/crypto/eseqiv.c b/crypto/eseqiv.c
new file mode 100644
index 000000000000..eb90d27ae118
--- /dev/null
+++ b/crypto/eseqiv.c
@@ -0,0 +1,264 @@
+/*
+ * eseqiv: Encrypted Sequence Number IV Generator
+ *
+ * This generator generates an IV based on a sequence number by xoring it
+ * with a salt and then encrypting it with the same key as used to encrypt
+ * the plain text.  This algorithm requires that the block size be equal
+ * to the IV size.  It is mainly useful for CBC.
+ *
+ * Copyright (c) 2007 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/skcipher.h>
+#include <crypto/scatterwalk.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+struct eseqiv_request_ctx {
+        struct scatterlist src[2];
+        struct scatterlist dst[2];
+        char tail[];
+};
+
+struct eseqiv_ctx {
+        spinlock_t lock;
+        unsigned int reqoff;
+        char salt[];
+};
+
+static void eseqiv_complete2(struct skcipher_givcrypt_request *req)
+{
+        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
+        struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
+
+        memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail,
+                         crypto_ablkcipher_alignmask(geniv) + 1),
+               crypto_ablkcipher_ivsize(geniv));
+}
+
+static void eseqiv_complete(struct crypto_async_request *base, int err)
+{
+        struct skcipher_givcrypt_request *req = base->data;
+
+        if (err)
+                goto out;
+
+        eseqiv_complete2(req);
+
+out:
+        skcipher_givcrypt_complete(req, err);
+}
+
+static void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg,
+                         int chain)
+{
+        if (chain) {
+                head->length += sg->length;
+                sg = scatterwalk_sg_next(sg);
+        }
+
+        if (sg)
+                scatterwalk_sg_chain(head, 2, sg);
+        else
+                sg_mark_end(head);
+}
+
+static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
+{
+        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
+        struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+        struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
+        struct ablkcipher_request *subreq;
+        crypto_completion_t complete;
+        void *data;
+        struct scatterlist *osrc, *odst;
+        struct scatterlist *dst;
+        struct page *srcp;
+        struct page *dstp;
+        u8 *giv;
+        u8 *vsrc;
+        u8 *vdst;
+        __be64 seq;
+        unsigned int ivsize;
+        unsigned int len;
+        int err;
+
+        subreq = (void *)(reqctx->tail + ctx->reqoff);
+        ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
+
+        giv = req->giv;
+        complete = req->creq.base.complete;
+        data = req->creq.base.data;
+
+        osrc = req->creq.src;
+        odst = req->creq.dst;
+        srcp = sg_page(osrc);
+        dstp = sg_page(odst);
+        vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
+        vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;
+
+        ivsize = crypto_ablkcipher_ivsize(geniv);
+
+        if (vsrc != giv + ivsize && vdst != giv + ivsize) {
+                giv = PTR_ALIGN((u8 *)reqctx->tail,
+                                crypto_ablkcipher_alignmask(geniv) + 1);
+                complete = eseqiv_complete;
+                data = req;
+        }
+
+        ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
+                                        data);
+
+        sg_init_table(reqctx->src, 2);
+        sg_set_buf(reqctx->src, giv, ivsize);
+        eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize);
+
+        dst = reqctx->src;
+        if (osrc != odst) {
+                sg_init_table(reqctx->dst, 2);
+                sg_set_buf(reqctx->dst, giv, ivsize);
+                eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize);
+
+                dst = reqctx->dst;
+        }
+
+        ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
+                                     req->creq.nbytes, req->creq.info);
+
+        memcpy(req->creq.info, ctx->salt, ivsize);
+
+        len = ivsize;
+        if (ivsize > sizeof(u64)) {
+                memset(req->giv, 0, ivsize - sizeof(u64));
+                len = sizeof(u64);
+        }
+        seq = cpu_to_be64(req->seq);
+        memcpy(req->giv + ivsize - len, &seq, len);
+
+        err = crypto_ablkcipher_encrypt(subreq);
+        if (err)
+                goto out;
+
+        eseqiv_complete2(req);
+
+out:
+        return err;
+}
+
+static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
+{
+        struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
+        struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+
+        spin_lock_bh(&ctx->lock);
+        if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first)
+                goto unlock;
+
+        crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt;
+        get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv));
+
+unlock:
+        spin_unlock_bh(&ctx->lock);
+
+        return eseqiv_givencrypt(req);
+}
+
+static int eseqiv_init(struct crypto_tfm *tfm)
+{
+        struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
+        struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+        unsigned long alignmask;
+        unsigned int reqsize;
+
+        spin_lock_init(&ctx->lock);
+
+        alignmask = crypto_tfm_ctx_alignment() - 1;
+        reqsize = sizeof(struct eseqiv_request_ctx);
+
+        if (alignmask & reqsize) {
+                alignmask &= reqsize;
+                alignmask--;
+        }
+
+        alignmask = ~alignmask;
+        alignmask &= crypto_ablkcipher_alignmask(geniv);
+
+        reqsize += alignmask;
+        reqsize += crypto_ablkcipher_ivsize(geniv);
+        reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());
+
+        ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx);
+
+        tfm->crt_ablkcipher.reqsize = reqsize +
+                                      sizeof(struct ablkcipher_request);
+
+        return skcipher_geniv_init(tfm);
+}
+
+static struct crypto_template eseqiv_tmpl;
+
+static struct crypto_instance *eseqiv_alloc(struct rtattr **tb)
+{
+        struct crypto_instance *inst;
+        int err;
+
+        inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
+        if (IS_ERR(inst))
+                goto out;
+
+        err = -EINVAL;
+        if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize)
+                goto free_inst;
+
+        inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first;
+
+        inst->alg.cra_init = eseqiv_init;
+        inst->alg.cra_exit = skcipher_geniv_exit;
+
+        inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx);
+        inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
+
+out:
+        return inst;
+
+free_inst:
+        skcipher_geniv_free(inst);
+        inst = ERR_PTR(err);
+        goto out;
+}
+
+static struct crypto_template eseqiv_tmpl = {
+        .name = "eseqiv",
+        .alloc = eseqiv_alloc,
+        .free = skcipher_geniv_free,
+        .module = THIS_MODULE,
+};
+
+static int __init eseqiv_module_init(void)
+{
+        return crypto_register_template(&eseqiv_tmpl);
+}
+
+static void __exit eseqiv_module_exit(void)
+{
+        crypto_unregister_template(&eseqiv_tmpl);
+}
+
+module_init(eseqiv_module_init);
+module_exit(eseqiv_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");