[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 <keesc...@chromium.org>
---
 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