4 files changed, 65 insertions, 7 deletions

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 650b1b3620d81..00c827d9f0d2d 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1296,6 +1296,49 @@ config CRYPTO_JITTERENTROPY
 
 	  See https://www.chronox.de/jent.html
 
+choice
+	prompt "CPU Jitter RNG Memory Size"
+	default CRYPTO_JITTERENTROPY_MEMSIZE_2
+	depends on CRYPTO_JITTERENTROPY
+	help
+	  The Jitter RNG measures the execution time of memory accesses.
+	  Multiple consecutive memory accesses are performed. If the memory
+	  size fits into a cache (e.g. L1), only the memory access timing
+	  to that cache is measured. The closer the cache is to the CPU
+	  the less variations are measured and thus the less entropy is
+	  obtained. Thus, if the memory size fits into the L1 cache, the
+	  obtained entropy is less than if the memory size fits within
+	  L1 + L2, which in turn is less if the memory fits into
+	  L1 + L2 + L3. Thus, by selecting a different memory size,
+	  the entropy rate produced by the Jitter RNG can be modified.
+
+	config CRYPTO_JITTERENTROPY_MEMSIZE_2
+		bool "2048 Bytes (default)"
+
+	config CRYPTO_JITTERENTROPY_MEMSIZE_128
+		bool "128 kBytes"
+
+	config CRYPTO_JITTERENTROPY_MEMSIZE_1024
+		bool "1024 kBytes"
+
+	config CRYPTO_JITTERENTROPY_MEMSIZE_8192
+		bool "8192 kBytes"
+endchoice
+
+config CRYPTO_JITTERENTROPY_MEMORY_BLOCKS
+	int
+	default 64 if CRYPTO_JITTERENTROPY_MEMSIZE_2
+	default 512 if CRYPTO_JITTERENTROPY_MEMSIZE_128
+	default 1024 if CRYPTO_JITTERENTROPY_MEMSIZE_1024
+	default 4096 if CRYPTO_JITTERENTROPY_MEMSIZE_8192
+
+config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE
+	int
+	default 32 if CRYPTO_JITTERENTROPY_MEMSIZE_2
+	default 256 if CRYPTO_JITTERENTROPY_MEMSIZE_128
+	default 1024 if CRYPTO_JITTERENTROPY_MEMSIZE_1024
+	default 2048 if CRYPTO_JITTERENTROPY_MEMSIZE_8192
+
 config CRYPTO_JITTERENTROPY_TESTINTERFACE
 	bool "CPU Jitter RNG Test Interface"
 	depends on CRYPTO_JITTERENTROPY
diff --git a/crypto/jitterentropy-kcapi.c b/crypto/jitterentropy-kcapi.c
index 1de730f946830..a8e7bbd28c6eb 100644
--- a/crypto/jitterentropy-kcapi.c
+++ b/crypto/jitterentropy-kcapi.c
@@ -54,6 +54,17 @@
  * Helper function
  ***************************************************************************/
 
+void *jent_kvzalloc(unsigned int len)
+{
+	return kvzalloc(len, GFP_KERNEL);
+}
+
+void jent_kvzfree(void *ptr, unsigned int len)
+{
+	memzero_explicit(ptr, len);
+	kvfree(ptr);
+}
+
 void *jent_zalloc(unsigned int len)
 {
 	return kzalloc(len, GFP_KERNEL);
diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c
index 1b99ffaa8c349..18bbe2b89a94d 100644
--- a/crypto/jitterentropy.c
+++ b/crypto/jitterentropy.c
@@ -75,10 +75,10 @@ struct rand_data {
 
 	unsigned int flags;		/* Flags used to initialize */
 	unsigned int osr;		/* Oversample rate */
-#define JENT_MEMORY_BLOCKS 64
-#define JENT_MEMORY_BLOCKSIZE 32
 #define JENT_MEMORY_ACCESSLOOPS 128
-#define JENT_MEMORY_SIZE (JENT_MEMORY_BLOCKS*JENT_MEMORY_BLOCKSIZE)
+#define JENT_MEMORY_SIZE						\
+	(CONFIG_CRYPTO_JITTERENTROPY_MEMORY_BLOCKS *			\
+	 CONFIG_CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE)
 	unsigned char *mem;	/* Memory access location with size of
 				 * memblocks * memblocksize */
 	unsigned int memlocation; /* Pointer to byte in *mem */
@@ -650,13 +650,15 @@ struct rand_data *jent_entropy_collector_alloc(unsigned int osr,
 		/* Allocate memory for adding variations based on memory
 		 * access
 		 */
-		entropy_collector->mem = jent_zalloc(JENT_MEMORY_SIZE);
+		entropy_collector->mem = jent_kvzalloc(JENT_MEMORY_SIZE);
 		if (!entropy_collector->mem) {
 			jent_zfree(entropy_collector);
 			return NULL;
 		}
-		entropy_collector->memblocksize = JENT_MEMORY_BLOCKSIZE;
-		entropy_collector->memblocks = JENT_MEMORY_BLOCKS;
+		entropy_collector->memblocksize =
+			CONFIG_CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE;
+		entropy_collector->memblocks =
+			CONFIG_CRYPTO_JITTERENTROPY_MEMORY_BLOCKS;
 		entropy_collector->memaccessloops = JENT_MEMORY_ACCESSLOOPS;
 	}
 
@@ -679,7 +681,7 @@ struct rand_data *jent_entropy_collector_alloc(unsigned int osr,
 
 void jent_entropy_collector_free(struct rand_data *entropy_collector)
 {
-	jent_zfree(entropy_collector->mem);
+	jent_kvzfree(entropy_collector->mem, JENT_MEMORY_SIZE);
 	entropy_collector->mem = NULL;
 	jent_zfree(entropy_collector);
 }
diff --git a/crypto/jitterentropy.h b/crypto/jitterentropy.h
index 626c6228b7e2b..e31661ee00d37 100644
--- a/crypto/jitterentropy.h
+++ b/crypto/jitterentropy.h
@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+extern void *jent_kvzalloc(unsigned int len);
+extern void jent_kvzfree(void *ptr, unsigned int len);
 extern void *jent_zalloc(unsigned int len);
 extern void jent_zfree(void *ptr);
 extern void jent_get_nstime(__u64 *out);