crypto: drbg - in-place cipher operation for CTR
The cipher implementations of the kernel crypto API favor in-place
cipher operations. Thus, switch the CTR cipher operation in the DRBG to
perform in-place operations. This is implemented by using the output
buffer as input buffer and zeroizing it before the cipher operation to
implement a CTR encryption of a NULL buffer.
The speed improvement is quite visibile with the following comparison
using the LRNG implementation.
Without the patch set:
16 bytes| 12.267661 MB/s| 61338304 bytes | 5000000213 ns
32 bytes| 23.603770 MB/s| 118018848 bytes | 5000000073 ns
64 bytes| 46.732262 MB/s| 233661312 bytes | 5000000241 ns
128 bytes| 90.038042 MB/s| 450190208 bytes | 5000000244 ns
256 bytes| 160.399616 MB/s| 801998080 bytes | 5000000393 ns
512 bytes| 259.878400 MB/s| 1299392000 bytes | 5000001675 ns
1024 bytes| 386.050662 MB/s| 1930253312 bytes | 5000001661 ns
2048 bytes| 493.641728 MB/s| 2468208640 bytes | 5000001598 ns
4096 bytes| 581.835981 MB/s| 2909179904 bytes | 5000003426 ns
With the patch set:
16 bytes | 17.051142 MB/s | 85255712 bytes | 5000000854 ns
32 bytes | 32.695898 MB/s | 163479488 bytes | 5000000544 ns
64 bytes | 64.490739 MB/s | 322453696 bytes | 5000000954 ns
128 bytes | 123.285043 MB/s | 616425216 bytes | 5000000201 ns
256 bytes | 233.434573 MB/s | 1167172864 bytes | 5000000573 ns
512 bytes | 384.405197 MB/s | 1922025984 bytes | 5000000671 ns
1024 bytes | 566.313370 MB/s | 2831566848 bytes | 5000001080 ns
2048 bytes | 744.518042 MB/s | 3722590208 bytes | 5000000926 ns
4096 bytes | 867.501670 MB/s | 4337508352 bytes | 5000002181 ns
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/drbg.c b/crypto/drbg.c
index ee302fd..bc52d95 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -261,8 +261,7 @@
static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
u8 *inbuf, u32 inbuflen,
u8 *outbuf, u32 outlen);
-#define DRBG_CTR_NULL_LEN 128
-#define DRBG_OUTSCRATCHLEN DRBG_CTR_NULL_LEN
+#define DRBG_OUTSCRATCHLEN 256
/* BCC function for CTR DRBG as defined in 10.4.3 */
static int drbg_ctr_bcc(struct drbg_state *drbg,
@@ -555,8 +554,7 @@
}
/* 10.2.1.5.2 step 4.1 */
- ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN,
- buf, len);
+ ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
if (ret)
return ret;
@@ -1644,9 +1642,6 @@
skcipher_request_free(drbg->ctr_req);
drbg->ctr_req = NULL;
- kfree(drbg->ctr_null_value_buf);
- drbg->ctr_null_value = NULL;
-
kfree(drbg->outscratchpadbuf);
drbg->outscratchpadbuf = NULL;
@@ -1697,15 +1692,6 @@
crypto_req_done, &drbg->ctr_wait);
alignmask = crypto_skcipher_alignmask(sk_tfm);
- drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
- GFP_KERNEL);
- if (!drbg->ctr_null_value_buf) {
- drbg_fini_sym_kernel(drbg);
- return -ENOMEM;
- }
- drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf,
- alignmask + 1);
-
drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
GFP_KERNEL);
if (!drbg->outscratchpadbuf) {
@@ -1716,7 +1702,7 @@
alignmask + 1);
sg_init_table(&drbg->sg_in, 1);
- sg_init_table(&drbg->sg_out, 1);
+ sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
return alignmask;
}
@@ -1747,10 +1733,18 @@
u8 *outbuf, u32 outlen)
{
struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
+ u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
int ret;
- sg_set_buf(sg_in, inbuf, inlen);
- sg_set_buf(sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
+ if (inbuf) {
+ /* Use caller-provided input buffer */
+ sg_set_buf(sg_in, inbuf, inlen);
+ } else {
+ /* Use scratchpad for in-place operation */
+ inlen = scratchpad_use;
+ memset(drbg->outscratchpad, 0, scratchpad_use);
+ sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
+ }
while (outlen) {
u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
@@ -1766,6 +1760,7 @@
crypto_init_wait(&drbg->ctr_wait);
memcpy(outbuf, drbg->outscratchpad, cryptlen);
+ memzero_explicit(drbg->outscratchpad, cryptlen);
outlen -= cryptlen;
outbuf += cryptlen;
@@ -1773,7 +1768,6 @@
ret = 0;
out:
- memzero_explicit(drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
return ret;
}
#endif /* CONFIG_CRYPTO_DRBG_CTR */
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index 54b9f5d3..3fb581b 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -122,8 +122,6 @@
struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */
struct skcipher_request *ctr_req; /* CTR mode request handle */
- __u8 *ctr_null_value_buf; /* CTR mode unaligned buffer */
- __u8 *ctr_null_value; /* CTR mode aligned zero buf */
__u8 *outscratchpadbuf; /* CTR mode output scratchpad */
__u8 *outscratchpad; /* CTR mode aligned outbuf */
struct crypto_wait ctr_wait; /* CTR mode async wait obj */