Subject: [RFC PATCH 03/21] crypto: acompress - Drop destination scatterlist allocation feature

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 18 Jul 2023 14:58:29 +0200

The acomp crypto code will allocate a destination scatterlist and its
backing pages on the fly if no destination is passed. This feature is
not used, and given that the caller should own this memory, it is far
better if the caller allocates it. This is especially true for
decompression, where the output size is essentially unbounded, and so
the caller already needs to provide the size for this feature to work
reliably.

Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 crypto/acompress.c         |  6 ----
 crypto/scompress.c         | 14 +---------
 crypto/testmgr.c           | 29 --------------------
 include/crypto/acompress.h | 16 ++---------
 4 files changed, 4 insertions(+), 61 deletions(-)

diff --git a/crypto/acompress.c b/crypto/acompress.c
index 1c682810a484dcdf..431876b0ee2096fd 100644
--- a/crypto/acompress.c
+++ b/crypto/acompress.c
@@ -71,7 +71,6 @@ static int crypto_acomp_init_tfm(struct crypto_tfm *tfm)
 
 	acomp->compress = alg->compress;
 	acomp->decompress = alg->decompress;
-	acomp->dst_free = alg->dst_free;
 	acomp->reqsize = alg->reqsize;
 
 	if (alg->exit)
@@ -173,11 +172,6 @@ void acomp_request_free(struct acomp_req *req)
 	if (tfm->__crt_alg->cra_type != &crypto_acomp_type)
 		crypto_acomp_scomp_free_ctx(req);
 
-	if (req->flags & CRYPTO_ACOMP_ALLOC_OUTPUT) {
-		acomp->dst_free(req->dst);
-		req->dst = NULL;
-	}
-
 	__acomp_request_free(req);
 }
 EXPORT_SYMBOL_GPL(acomp_request_free);
diff --git a/crypto/scompress.c b/crypto/scompress.c
index 442a82c9de7def1f..3155cdce9116e092 100644
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -122,12 +122,9 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
 		return -EINVAL;
 
-	if (req->dst && !req->dlen)
+	if (!req->dst || !req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
 		return -EINVAL;
 
-	if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
-		req->dlen = SCOMP_SCRATCH_SIZE;
-
 	scratch = raw_cpu_ptr(&scomp_scratch);
 	spin_lock(&scratch->lock);
 
@@ -139,17 +136,9 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 		ret = crypto_scomp_decompress(scomp, scratch->src, req->slen,
 					      scratch->dst, &req->dlen, *ctx);
 	if (!ret) {
-		if (!req->dst) {
-			req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
-			if (!req->dst) {
-				ret = -ENOMEM;
-				goto out;
-			}
-		}
 		scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
 					 1);
 	}
-out:
 	spin_unlock(&scratch->lock);
 	return ret;
 }
@@ -197,7 +186,6 @@ int crypto_init_scomp_ops_async(struct crypto_tfm *tfm)
 
 	crt->compress = scomp_acomp_compress;
 	crt->decompress = scomp_acomp_decompress;
-	crt->dst_free = sgl_free;
 	crt->reqsize = sizeof(void *);
 
 	return 0;
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index b41a8e8c1d1a1987..4971351f55dbabb9 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -3497,21 +3497,6 @@ static int test_acomp(struct crypto_acomp *tfm,
 			goto out;
 		}
 
-#ifdef CONFIG_CRYPTO_MANAGER_EXTRA_TESTS
-		crypto_init_wait(&wait);
-		sg_init_one(&src, input_vec, ilen);
-		acomp_request_set_params(req, &src, NULL, ilen, 0);
-
-		ret = crypto_wait_req(crypto_acomp_compress(req), &wait);
-		if (ret) {
-			pr_err("alg: acomp: compression failed on NULL dst buffer test %d for %s: ret=%d\n",
-			       i + 1, algo, -ret);
-			kfree(input_vec);
-			acomp_request_free(req);
-			goto out;
-		}
-#endif
-
 		kfree(input_vec);
 		acomp_request_free(req);
 	}
@@ -3573,20 +3558,6 @@ static int test_acomp(struct crypto_acomp *tfm,
 			goto out;
 		}
 
-#ifdef CONFIG_CRYPTO_MANAGER_EXTRA_TESTS
-		crypto_init_wait(&wait);
-		acomp_request_set_params(req, &src, NULL, ilen, 0);
-
-		ret = crypto_wait_req(crypto_acomp_decompress(req), &wait);
-		if (ret) {
-			pr_err("alg: acomp: decompression failed on NULL dst buffer test %d for %s: ret=%d\n",
-			       i + 1, algo, -ret);
-			kfree(input_vec);
-			acomp_request_free(req);
-			goto out;
-		}
-#endif
-
 		kfree(input_vec);
 		acomp_request_free(req);
 	}
diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
index 574cffc90730f5f3..ccb6f3279bc8b32e 100644
--- a/include/crypto/acompress.h
+++ b/include/crypto/acompress.h
@@ -43,15 +43,12 @@ struct acomp_req {
  *
  * @compress:		Function performs a compress operation
  * @decompress:		Function performs a de-compress operation
- * @dst_free:		Frees destination buffer if allocated inside the
- *			algorithm
  * @reqsize:		Context size for (de)compression requests
  * @base:		Common crypto API algorithm data structure
  */
 struct crypto_acomp {
 	int (*compress)(struct acomp_req *req);
 	int (*decompress)(struct acomp_req *req);
-	void (*dst_free)(struct scatterlist *dst);
 	unsigned int reqsize;
 	struct crypto_tfm base;
 };
@@ -222,8 +219,7 @@ static inline void acomp_request_set_callback(struct acomp_req *req,
 {
 	req->base.complete = cmpl;
 	req->base.data = data;
-	req->base.flags &= CRYPTO_ACOMP_ALLOC_OUTPUT;
-	req->base.flags |= flgs & ~CRYPTO_ACOMP_ALLOC_OUTPUT;
+	req->base.flags = flgs;
 }
 
 /**
@@ -233,11 +229,9 @@ static inline void acomp_request_set_callback(struct acomp_req *req,
  *
  * @req:	asynchronous compress request
  * @src:	pointer to input buffer scatterlist
- * @dst:	pointer to output buffer scatterlist. If this is NULL, the
- *		acomp layer will allocate the output memory
+ * @dst:	pointer to output buffer scatterlist
  * @slen:	size of the input buffer
- * @dlen:	size of the output buffer. If dst is NULL, this can be used by
- *		the user to specify the maximum amount of memory to allocate
+ * @dlen:	size of the output buffer
  */
 static inline void acomp_request_set_params(struct acomp_req *req,
 					    struct scatterlist *src,
@@ -249,10 +243,6 @@ static inline void acomp_request_set_params(struct acomp_req *req,
 	req->dst = dst;
 	req->slen = slen;
 	req->dlen = dlen;
-
-	req->flags &= ~CRYPTO_ACOMP_ALLOC_OUTPUT;
-	if (!req->dst)
-		req->flags |= CRYPTO_ACOMP_ALLOC_OUTPUT;
 }
 
 static inline struct crypto_istat_compress *comp_get_stat(
-- 
2.39.2