crypto: aead - Add support for on-stack AEAD req allocation

This patch introduces infrastructure for allocating req objects on the
stack for AEADs. The additions mirror the existing sync skcipher APIs.
This can be used in cases where simple sync AEAD operations are being
done. So allocating the request on stack avoides possible out-of-memory
errors.

The struct crypto_sync_aead is a wrapper around crypto_aead and should
be used in its place when sync only requests will be done on the stack.
Correspondingly, the request should be allocated with
SYNC_AEAD_REQUEST_ON_STACK().

Similar to sync_skcipher APIs, the new sync_aead APIs are wrappers
around the regular aead APIs to facilitate sync only operations. The
following crypto APIs are added:
- struct crypto_sync_aead
- crypto_alloc_sync_aead()
- crypto_free_sync_aead()
- crypto_aync_aead_tfm()
- crypto_sync_aead_setkey()
- crypto_sync_aead_setauthsize()
- crypto_sync_aead_authsize()
- crypto_sync_aead_maxauthsize()
- crypto_sync_aead_ivsize()
- crypto_sync_aead_blocksize()
- crypto_sync_aead_get_flags()
- crypto_sync_aead_set_flags()
- crypto_sync_aead_clear_flags()
- crypto_sync_aead_reqtfm()
- aead_request_set_sync_tfm()
- SYNC_AEAD_REQUEST_ON_STACK()

Signed-off-by: T Pratham <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/aead.c

···
 }
 EXPORT_SYMBOL_GPL(crypto_alloc_aead);
 
+struct crypto_sync_aead *crypto_alloc_sync_aead(const char *alg_name, u32 type, u32 mask)
+{
+	struct crypto_aead *tfm;
+
+	/* Only sync algorithms are allowed. */
+	mask |= CRYPTO_ALG_ASYNC;
+	type &= ~(CRYPTO_ALG_ASYNC);
+
+	tfm = crypto_alloc_tfm(alg_name, &crypto_aead_type, type, mask);
+
+	if (!IS_ERR(tfm) && WARN_ON(crypto_aead_reqsize(tfm) > MAX_SYNC_AEAD_REQSIZE)) {
+		crypto_free_aead(tfm);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return (struct crypto_sync_aead *)tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_sync_aead);
+
 int crypto_has_aead(const char *alg_name, u32 type, u32 mask)
 {
 	return crypto_type_has_alg(alg_name, &crypto_aead_type, type, mask);

include/crypto/aead.h

···
 	struct crypto_tfm base;
 };
 
+struct crypto_sync_aead {
+	struct crypto_aead base;
+};
+
+#define MAX_SYNC_AEAD_REQSIZE		384
+
+#define SYNC_AEAD_REQUEST_ON_STACK(name, _tfm)		\
+	char __##name##_desc[sizeof(struct aead_request) +	\
+			     MAX_SYNC_AEAD_REQSIZE		\
+			    ] CRYPTO_MINALIGN_ATTR;		\
+	struct aead_request *name =				\
+		(((struct aead_request *)__##name##_desc)->base.tfm = \
+			crypto_sync_aead_tfm((_tfm)),		\
+		 (void *)__##name##_desc)
+
 static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
 {
 	return container_of(tfm, struct crypto_aead, base);
···
  */
 struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
 
+struct crypto_sync_aead *crypto_alloc_sync_aead(const char *alg_name, u32 type, u32 mask);
+
 static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
 {
 	return &tfm->base;
+}
+
+static inline struct crypto_tfm *crypto_sync_aead_tfm(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_tfm(&tfm->base);
 }
 
 /**
···
 static inline void crypto_free_aead(struct crypto_aead *tfm)
 {
 	crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
+}
+
+static inline void crypto_free_sync_aead(struct crypto_sync_aead *tfm)
+{
+	crypto_free_aead(&tfm->base);
 }
 
 /**
···
 	return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
 }
 
+static inline unsigned int crypto_sync_aead_ivsize(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_ivsize(&tfm->base);
+}
+
 /**
  * crypto_aead_authsize() - obtain maximum authentication data size
  * @tfm: cipher handle
···
 	return tfm->authsize;
 }
 
+static inline unsigned int crypto_sync_aead_authsize(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_authsize(&tfm->base);
+}
+
 static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)
 {
 	return alg->maxauthsize;
···
 static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)
 {
 	return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));
+}
+
+static inline unsigned int crypto_sync_aead_maxauthsize(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_maxauthsize(&tfm->base);
 }
 
 /**
···
 static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
 {
 	return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
+}
+
+static inline unsigned int crypto_sync_aead_blocksize(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_blocksize(&tfm->base);
 }
 
 static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
···
 	crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
 }
 
+static inline u32 crypto_sync_aead_get_flags(struct crypto_sync_aead *tfm)
+{
+	return crypto_aead_get_flags(&tfm->base);
+}
+
+static inline void crypto_sync_aead_set_flags(struct crypto_sync_aead *tfm, u32 flags)
+{
+	crypto_aead_set_flags(&tfm->base, flags);
+}
+
+static inline void crypto_sync_aead_clear_flags(struct crypto_sync_aead *tfm, u32 flags)
+{
+	crypto_aead_clear_flags(&tfm->base, flags);
+}
+
 /**
  * crypto_aead_setkey() - set key for cipher
  * @tfm: cipher handle
···
 int crypto_aead_setkey(struct crypto_aead *tfm,
 		       const u8 *key, unsigned int keylen);
 
+static inline int crypto_sync_aead_setkey(struct crypto_sync_aead *tfm,
+					 const u8 *key, unsigned int keylen)
+{
+	return crypto_aead_setkey(&tfm->base, key, keylen);
+}
+
 /**
  * crypto_aead_setauthsize() - set authentication data size
  * @tfm: cipher handle
···
  */
 int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
 
+static inline int crypto_sync_aead_setauthsize(struct crypto_sync_aead *tfm,
+					       unsigned int authsize)
+{
+	return crypto_aead_setauthsize(&tfm->base, authsize);
+}
+
 static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
 {
 	return __crypto_aead_cast(req->base.tfm);
+}
+
+static inline struct crypto_sync_aead *crypto_sync_aead_reqtfm(struct aead_request *req)
+{
+	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
+
+	return container_of(tfm, struct crypto_sync_aead, base);
 }
 
 /**
···
 					struct crypto_aead *tfm)
 {
 	req->base.tfm = crypto_aead_tfm(tfm);
+}
+
+static inline void aead_request_set_sync_tfm(struct aead_request *req,
+					     struct crypto_sync_aead *tfm)
+{
+	aead_request_set_tfm(req, &tfm->base);
 }
 
 /**