[PATCH 1/9] crypto: add zbufsize() interface

Kees Cook
2018-08-02T21:52:24Z

When pstore was refactored to use the crypto compress API in:

commit cb3bee0369bc ("pstore: Use crypto compress API")

nearly all the pstore-specific compression routines were replaced with
the existing crypto compression API. One case remained: calculating the
"worst case" compression sizes ahead of time so it could have a buffer
preallocated for doing compression (which was called "zbufsize").

To make pstore fully algorithm-agnostic, the compression API needs to
grow this functionality. This adds the interface to support querying the
"worst case" estimate, with a new "zbufsize" routine that each compressor
can implement. The per-compressor implementations come in later commits.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
crypto/compress.c | 9 +++++++++
include/crypto/internal/scompress.h | 11 +++++++++++
include/linux/crypto.h | 12 ++++++++++++
3 files changed, 32 insertions(+)

diff --git a/crypto/compress.c b/crypto/compress.c
index f2d522924a07..29a80bb3b9d3 100644
--- a/crypto/compress.c
+++ b/crypto/compress.c
@@ -33,12 +33,21 @@ static int crypto_decompress(struct crypto_tfm *tfm,
dlen);
}

+static int crypto_zbufsize(struct crypto_tfm *tfm,
+ unsigned int slen, unsigned int *dlen)
+{
+ if (!tfm->__crt_alg->cra_compress.coa_zbufsize)
+ return -ENOTSUPP;
+ return tfm->__crt_alg->cra_compress.coa_zbufsize(tfm, slen, dlen);
+}
+
int crypto_init_compress_ops(struct crypto_tfm *tfm)
{
struct compress_tfm *ops = &tfm->crt_compress;

ops->cot_compress = crypto_compress;
ops->cot_decompress = crypto_decompress;
+ ops->cot_zbufsize = crypto_zbufsize;

return 0;
}
diff --git a/include/crypto/internal/scompress.h b/include/crypto/internal/scompress.h
index 0f6ddac1acfc..a4a2a55080ad 100644
--- a/include/crypto/internal/scompress.h
+++ b/include/crypto/internal/scompress.h
@@ -39,6 +39,8 @@ struct scomp_alg {
int (*decompress)(struct crypto_scomp *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen,
void *ctx);
+ int (*zbufsize)(struct crypto_scomp *tfm, unsigned int slen,
+ unsigned int *dlen, void *ctx);
struct crypto_alg base;
};

@@ -94,6 +96,15 @@ static inline int crypto_scomp_decompress(struct crypto_scomp *tfm,
ctx);
}

+static inline int crypto_scomp_zbufsize(struct crypto_scomp *tfm,
+ unsigned int slen,
+ unsigned int *dlen, void *ctx)
+{
+ if (!crypto_scomp_alg(tfm)->zbufsize)
+ return -ENOTSUPP;
+ return crypto_scomp_alg(tfm)->zbufsize(tfm, slen, dlen, ctx);
+}
+
int crypto_init_scomp_ops_async(struct crypto_tfm *tfm);
struct acomp_req *crypto_acomp_scomp_alloc_ctx(struct acomp_req *req);
void crypto_acomp_scomp_free_ctx(struct acomp_req *req);
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index 6eb06101089f..376c056447e7 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -362,6 +362,8 @@ struct compress_alg {
unsigned int slen, u8 *dst, unsigned int *dlen);
int (*coa_decompress)(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen);
+ int (*coa_zbufsize)(struct crypto_tfm *tfm, unsigned int slen,
+ unsigned int *dlen);
};

@@ -578,6 +580,8 @@ struct compress_tfm {
int (*cot_decompress)(struct crypto_tfm *tfm,
const u8 *src, unsigned int slen,
u8 *dst, unsigned int *dlen);
+ int (*cot_zbufsize)(struct crypto_tfm *tfm,
+ unsigned int slen, unsigned int *dlen);
};

#define crt_ablkcipher crt_u.ablkcipher
@@ -1660,5 +1664,13 @@ static inline int crypto_comp_decompress(struct crypto_comp *tfm,
src, slen, dst, dlen);
}

+static inline int crypto_comp_zbufsize(struct crypto_comp *tfm,
+ unsigned int slen,
+ unsigned int *dlen)
+{
+ return crypto_comp_crt(tfm)->cot_zbufsize(crypto_comp_tfm(tfm),
+ slen, dlen);
+}
+
#endif /* _LINUX_CRYPTO_H */

--
2.17.1