[CRYPTO] skcipher: Add skcipher_geniv_alloc/skcipher_geniv_free

This patch creates the infrastructure to help the construction of givcipher
templates that wrap around existing blkcipher/ablkcipher algorithms by adding
an IV generator to them.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

4 files changed, 225 insertions, 6 deletions

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 8f48b4d58fca..092d9659b861 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -80,6 +80,7 @@ static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
         crt->setkey = setkey;
         crt->encrypt = alg->encrypt;
         crt->decrypt = alg->decrypt;
+        crt->base = __crypto_ablkcipher_cast(tfm);
         crt->ivsize = alg->ivsize;
 
         return 0;
@@ -122,11 +123,13 @@ static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
         if (alg->ivsize > PAGE_SIZE / 8)
                 return -EINVAL;
 
-        crt->setkey = setkey;
+        crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
+                      alg->setkey : setkey;
         crt->encrypt = alg->encrypt;
         crt->decrypt = alg->decrypt;
         crt->givencrypt = alg->givencrypt;
         crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;
+        crt->base = __crypto_ablkcipher_cast(tfm);
         crt->ivsize = alg->ivsize;
 
         return 0;
@@ -155,6 +158,11 @@ const struct crypto_type crypto_givcipher_type = {
 };
 EXPORT_SYMBOL_GPL(crypto_givcipher_type);
 
+const char *crypto_default_geniv(const struct crypto_alg *alg)
+{
+        return alg->cra_flags & CRYPTO_ALG_ASYNC ? "eseqiv" : "chainiv";
+}
+
 int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn, const char *name,
                          u32 type, u32 mask)
 {
diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index 7a3e1a308074..ca6ef065cded 100644
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -14,8 +14,8 @@
  *
  */
 
+#include <crypto/internal/skcipher.h>
 #include <crypto/scatterwalk.h>
-#include <linux/crypto.h>
 #include <linux/errno.h>
 #include <linux/hardirq.h>
 #include <linux/kernel.h>
@@ -450,6 +450,7 @@ static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
         crt->setkey = async_setkey;
         crt->encrypt = async_encrypt;
         crt->decrypt = async_decrypt;
+        crt->base = __crypto_ablkcipher_cast(tfm);
         crt->ivsize = alg->ivsize;
 
         return 0;
@@ -509,5 +510,187 @@ const struct crypto_type crypto_blkcipher_type = {
 };
 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
 
+static int crypto_grab_nivcipher(struct crypto_skcipher_spawn *spawn,
+                                const char *name, u32 type, u32 mask)
+{
+        struct crypto_alg *alg;
+        int err;
+
+        type = crypto_skcipher_type(type);
+        mask = crypto_skcipher_mask(mask) | CRYPTO_ALG_GENIV;
+
+        alg = crypto_alg_mod_lookup(name, type, mask);
+        if (IS_ERR(alg))
+                return PTR_ERR(alg);
+
+        err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
+        crypto_mod_put(alg);
+        return err;
+}
+
+struct crypto_instance *skcipher_geniv_alloc(struct crypto_template *tmpl,
+                                             struct rtattr **tb, u32 type,
+                                             u32 mask)
+{
+        struct {
+                int (*setkey)(struct crypto_ablkcipher *tfm, const u8 *key,
+                              unsigned int keylen);
+                int (*encrypt)(struct ablkcipher_request *req);
+                int (*decrypt)(struct ablkcipher_request *req);
+
+                unsigned int min_keysize;
+                unsigned int max_keysize;
+                unsigned int ivsize;
+
+                const char *geniv;
+        } balg;
+        const char *name;
+        struct crypto_skcipher_spawn *spawn;
+        struct crypto_attr_type *algt;
+        struct crypto_instance *inst;
+        struct crypto_alg *alg;
+        int err;
+
+        algt = crypto_get_attr_type(tb);
+        err = PTR_ERR(algt);
+        if (IS_ERR(algt))
+                return ERR_PTR(err);
+
+        if ((algt->type ^ (CRYPTO_ALG_TYPE_GIVCIPHER | CRYPTO_ALG_GENIV)) &
+            algt->mask)
+                return ERR_PTR(-EINVAL);
+
+        name = crypto_attr_alg_name(tb[1]);
+        err = PTR_ERR(name);
+        if (IS_ERR(name))
+                return ERR_PTR(err);
+
+        inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+        if (!inst)
+                return ERR_PTR(-ENOMEM);
+
+        spawn = crypto_instance_ctx(inst);
+
+        /* Ignore async algorithms if necessary. */
+        mask |= crypto_requires_sync(algt->type, algt->mask);
+
+        crypto_set_skcipher_spawn(spawn, inst);
+        err = crypto_grab_nivcipher(spawn, name, type, mask);
+        if (err)
+                goto err_free_inst;
+
+        alg = crypto_skcipher_spawn_alg(spawn);
+
+        if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+            CRYPTO_ALG_TYPE_BLKCIPHER) {
+                balg.ivsize = alg->cra_blkcipher.ivsize;
+                balg.min_keysize = alg->cra_blkcipher.min_keysize;
+                balg.max_keysize = alg->cra_blkcipher.max_keysize;
+
+                balg.setkey = async_setkey;
+                balg.encrypt = async_encrypt;
+                balg.decrypt = async_decrypt;
+
+                balg.geniv = alg->cra_blkcipher.geniv;
+        } else {
+                balg.ivsize = alg->cra_ablkcipher.ivsize;
+                balg.min_keysize = alg->cra_ablkcipher.min_keysize;
+                balg.max_keysize = alg->cra_ablkcipher.max_keysize;
+
+                balg.setkey = alg->cra_ablkcipher.setkey;
+                balg.encrypt = alg->cra_ablkcipher.encrypt;
+                balg.decrypt = alg->cra_ablkcipher.decrypt;
+
+                balg.geniv = alg->cra_ablkcipher.geniv;
+        }
+
+        err = -EINVAL;
+        if (!balg.ivsize)
+                goto err_drop_alg;
+
+        /*
+         * This is only true if we're constructing an algorithm with its
+         * default IV generator.  For the default generator we elide the
+         * template name and double-check the IV generator.
+         */
+        if (algt->mask & CRYPTO_ALG_GENIV) {
+                if (!balg.geniv)
+                        balg.geniv = crypto_default_geniv(alg);
+                err = -EAGAIN;
+                if (strcmp(tmpl->name, balg.geniv))
+                        goto err_drop_alg;
+
+                memcpy(inst->alg.cra_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);
+                memcpy(inst->alg.cra_driver_name, alg->cra_driver_name,
+                       CRYPTO_MAX_ALG_NAME);
+        } else {
+                err = -ENAMETOOLONG;
+                if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+                             "%s(%s)", tmpl->name, alg->cra_name) >=
+                    CRYPTO_MAX_ALG_NAME)
+                        goto err_drop_alg;
+                if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+                             "%s(%s)", tmpl->name, alg->cra_driver_name) >=
+                    CRYPTO_MAX_ALG_NAME)
+                        goto err_drop_alg;
+        }
+
+        inst->alg.cra_flags = CRYPTO_ALG_TYPE_GIVCIPHER | CRYPTO_ALG_GENIV;
+        inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
+        inst->alg.cra_priority = alg->cra_priority;
+        inst->alg.cra_blocksize = alg->cra_blocksize;
+        inst->alg.cra_alignmask = alg->cra_alignmask;
+        inst->alg.cra_type = &crypto_givcipher_type;
+
+        inst->alg.cra_ablkcipher.ivsize = balg.ivsize;
+        inst->alg.cra_ablkcipher.min_keysize = balg.min_keysize;
+        inst->alg.cra_ablkcipher.max_keysize = balg.max_keysize;
+        inst->alg.cra_ablkcipher.geniv = balg.geniv;
+
+        inst->alg.cra_ablkcipher.setkey = balg.setkey;
+        inst->alg.cra_ablkcipher.encrypt = balg.encrypt;
+        inst->alg.cra_ablkcipher.decrypt = balg.decrypt;
+
+out:
+        return inst;
+
+err_drop_alg:
+        crypto_drop_skcipher(spawn);
+err_free_inst:
+        kfree(inst);
+        inst = ERR_PTR(err);
+        goto out;
+}
+EXPORT_SYMBOL_GPL(skcipher_geniv_alloc);
+
+void skcipher_geniv_free(struct crypto_instance *inst)
+{
+        crypto_drop_skcipher(crypto_instance_ctx(inst));
+        kfree(inst);
+}
+EXPORT_SYMBOL_GPL(skcipher_geniv_free);
+
+int skcipher_geniv_init(struct crypto_tfm *tfm)
+{
+        struct crypto_instance *inst = (void *)tfm->__crt_alg;
+        struct crypto_ablkcipher *cipher;
+
+        cipher = crypto_spawn_skcipher(crypto_instance_ctx(inst));
+        if (IS_ERR(cipher))
+                return PTR_ERR(cipher);
+
+        tfm->crt_ablkcipher.base = cipher;
+        tfm->crt_ablkcipher.reqsize += crypto_ablkcipher_reqsize(cipher);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(skcipher_geniv_init);
+
+void skcipher_geniv_exit(struct crypto_tfm *tfm)
+{
+        crypto_free_ablkcipher(tfm->crt_ablkcipher.base);
+}
+EXPORT_SYMBOL_GPL(skcipher_geniv_exit);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Generic block chaining cipher type");
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index c9402dd12d03..07e7c82324ad 100644
--- a/include/crypto/internal/skcipher.h
+++ b/include/crypto/internal/skcipher.h
@@ -15,6 +15,9 @@
 
 #include <crypto/algapi.h>
 #include <crypto/skcipher.h>
+#include <linux/types.h>
+
+struct rtattr;
 
 struct crypto_skcipher_spawn {
         struct crypto_spawn base;
@@ -50,6 +53,21 @@ static inline struct crypto_ablkcipher *crypto_spawn_skcipher(
                                  crypto_skcipher_mask(0)));
 }
 
+const char *crypto_default_geniv(const struct crypto_alg *alg);
+
+struct crypto_instance *skcipher_geniv_alloc(struct crypto_template *tmpl,
+                                             struct rtattr **tb, u32 type,
+                                             u32 mask);
+void skcipher_geniv_free(struct crypto_instance *inst);
+int skcipher_geniv_init(struct crypto_tfm *tfm);
+void skcipher_geniv_exit(struct crypto_tfm *tfm);
+
+static inline struct crypto_ablkcipher *skcipher_geniv_cipher(
+        struct crypto_ablkcipher *geniv)
+{
+        return crypto_ablkcipher_crt(geniv)->base;
+}
+
 static inline void *skcipher_givcrypt_reqctx(
         struct skcipher_givcrypt_request *req)
 {
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index facafa1bd8ca..fa7afa9b9f4f 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -53,6 +53,12 @@
 #define CRYPTO_ALG_NEED_FALLBACK        0x00000100
 
 /*
+ * This bit is set for symmetric key ciphers that have already been wrapped
+ * with a generic IV generator to prevent them from being wrapped again.
+ */
+#define CRYPTO_ALG_GENIV                0x00000200
+
+/*
  * Transform masks and values (for crt_flags).
  */
 #define CRYPTO_TFM_REQ_MASK             0x000fff00
@@ -331,6 +337,8 @@ struct ablkcipher_tfm {
         int (*givencrypt)(struct skcipher_givcrypt_request *req);
         int (*givdecrypt)(struct skcipher_givcrypt_request *req);
 
+        struct crypto_ablkcipher *base;
+
         unsigned int ivsize;
         unsigned int reqsize;
 };
@@ -541,14 +549,14 @@ static inline struct crypto_ablkcipher *__crypto_ablkcipher_cast(
 
 static inline u32 crypto_skcipher_type(u32 type)
 {
-        type &= ~CRYPTO_ALG_TYPE_MASK;
+        type &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
         type |= CRYPTO_ALG_TYPE_BLKCIPHER;
         return type;
 }
 
 static inline u32 crypto_skcipher_mask(u32 mask)
 {
-        mask &= ~CRYPTO_ALG_TYPE_MASK;
+        mask &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
         mask |= CRYPTO_ALG_TYPE_BLKCIPHER_MASK;
         return mask;
 }
@@ -623,7 +631,9 @@ static inline void crypto_ablkcipher_clear_flags(struct crypto_ablkcipher *tfm,
 static inline int crypto_ablkcipher_setkey(struct crypto_ablkcipher *tfm,
                                            const u8 *key, unsigned int keylen)
 {
-        return crypto_ablkcipher_crt(tfm)->setkey(tfm, key, keylen);
+        struct ablkcipher_tfm *crt = crypto_ablkcipher_crt(tfm);
+
+        return crt->setkey(crt->base, key, keylen);
 }
 
 static inline struct crypto_ablkcipher *crypto_ablkcipher_reqtfm(
@@ -655,7 +665,7 @@ static inline unsigned int crypto_ablkcipher_reqsize(
 static inline void ablkcipher_request_set_tfm(
         struct ablkcipher_request *req, struct crypto_ablkcipher *tfm)
 {
-        req->base.tfm = crypto_ablkcipher_tfm(tfm);
+        req->base.tfm = crypto_ablkcipher_tfm(crypto_ablkcipher_crt(tfm)->base);
 }
 
 static inline struct ablkcipher_request *ablkcipher_request_cast(