crypto: api - laying defines and checks for statically allocated buffers

In preparation for the removal of VLAs[1] from crypto code.
We create 2 new compile-time constants: all ciphers implemented
in Linux have a block size less than or equal to 16 bytes and
the most demanding hw require 16 bytes alignment for the block
buffer.
We also enforce these limits in crypto_check_alg when a new
cipher is registered.

[1] http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 1aba888241dd..bd5e8ccf1687 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -17,6 +17,14 @@
 #include <linux/kernel.h>
 #include <linux/skbuff.h>
 
+/*
+ * Maximum values for blocksize and alignmask, used to allocate
+ * static buffers that are big enough for any combination of
+ * ciphers and architectures.
+ */
+#define MAX_CIPHER_BLOCKSIZE		16
+#define MAX_CIPHER_ALIGNMASK		15
+
 struct crypto_aead;
 struct crypto_instance;
 struct module;