[PATCH 7/9] crypto, lz4: Implement zbufsize()

[Kees Cook]

This implements the worst-case compression size querying interface for
lz4, based on the logic originally used by pstore.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 crypto/lz4.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/crypto/lz4.c b/crypto/lz4.c
index 2ce2660d3519..42003d080967 100644
--- a/crypto/lz4.c
+++ b/crypto/lz4.c
@@ -117,6 +117,24 @@ static int lz4_decompress_crypto(struct crypto_tfm *tfm, const u8 *src,
 	return __lz4_decompress_crypto(src, slen, dst, dlen, NULL);
 }
 
+static int __lz4_zbufsize_crypto(unsigned int slen, unsigned int *dlen)
+{
+	*dlen = LZ4_compressBound(slen);
+	return 0;
+}
+
+static int lz4_szbufsize(struct crypto_scomp *tfm, unsigned int slen,
+			 unsigned int *dlen, void *ctx)
+{
+	return __lz4_zbufsize_crypto(slen, dlen);
+}
+
+static int lz4_zbufsize_crypto(struct crypto_tfm *tfm, unsigned int slen,
+			       unsigned int *dlen)
+{
+	return __lz4_zbufsize_crypto(slen, dlen);
+}
+
 static struct crypto_alg alg_lz4 = {
 	.cra_name		= "lz4",
 	.cra_flags		= CRYPTO_ALG_TYPE_COMPRESS,
@@ -127,7 +145,8 @@ static struct crypto_alg alg_lz4 = {
 	.cra_exit		= lz4_exit,
 	.cra_u			= { .compress = {
 	.coa_compress		= lz4_compress_crypto,
-	.coa_decompress		= lz4_decompress_crypto } }
+	.coa_decompress		= lz4_decompress_crypto,
+	.coa_zbufsize		= lz4_zbufsize_crypto } }
 };
 
 static struct scomp_alg scomp = {
@@ -135,6 +154,7 @@ static struct scomp_alg scomp = {
 	.free_ctx		= lz4_free_ctx,
 	.compress		= lz4_scompress,
 	.decompress		= lz4_sdecompress,
+	.zbufsize		= lz4_szbufsize,
 	.base			= {
 		.cra_name	= "lz4",
 		.cra_driver_name = "lz4-scomp",
-- 
2.17.1