It's just a union of various word sizes to address the buffer.
This achieves three things:
1) Aligns the buffers for (hopefully) slight performance benefit
2) Allows XOR to be done long-at-a-time
3) Prepares for later patches where I want int-at-a-time access
Signed-off-by: George Spelvin <linux@xxxxxxxxxxx>
---
crypto/ansi_cprng.c | 78 ++++++++++++++++++++++++++++++-----------------------
1 file changed, 44 insertions(+), 34 deletions(-)
This is the sort of style issue I fear will attract loud screams.
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 09bb1252..7b6b263d 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -26,6 +26,19 @@
#define DEFAULT_BLK_SZ 16
/*
+ * A cipher block is defined as a union, so we can address individual bytes,
+ * or do things word-at-a-time when byte order doesn't matter, such as XOR
+ * or adding in entropy.
+ */
+#define BLK_INTS ((DEFAULT_BLK_SZ-1) / sizeof(int) + 1)
+#define BLK_LONGS ((DEFAULT_BLK_SZ-1) / sizeof(long) + 1)
+union block {
+ unsigned char bytes[DEFAULT_BLK_SZ];
+ unsigned long ints[BLK_INTS];
+ unsigned long longs[BLK_LONGS];
+};
+
+/*
* Flags for the prng_context flags field
*/
@@ -46,23 +59,20 @@
*/
struct prng_context {
spinlock_t prng_lock;
- unsigned char rand_data[DEFAULT_BLK_SZ];
- unsigned char DT[DEFAULT_BLK_SZ];
- unsigned char V[DEFAULT_BLK_SZ];
- unsigned char rand_read_pos; /* Offset into rand_data[] */
+ unsigned char rand_read_pos; /* Offset into rand_data.bytes[] */
unsigned char flags;
+ union block rand_data, DT, V;
struct crypto_cipher *tfm;
};
static int dbg;
-static void hexdump(char const *note, void const *buf, unsigned int len)
+static void hexdump(char const *note, union block const *block)
{
if (dbg) {
printk(KERN_CRIT "%s", note);
print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
- 16, 1,
- buf, len, false);
+ 16, 1, block->bytes, DEFAULT_BLK_SZ, false);
}
}
@@ -71,12 +81,12 @@ if (dbg)\
printk(format, ##args);\
} while (0)
-static void xor_block(unsigned char const *in, unsigned char *out)
+static void xor_block(union block const *in, union block *out)
{
int i;
- for (i = 0; i < DEFAULT_BLK_SZ; i++)
- out[i] ^= in[i];
+ for (i = 0; i < BLK_LONGS; i++)
+ out->longs[i] ^= in->longs[i];
}
/*
* Returns DEFAULT_BLK_SZ bytes of random data per call
@@ -85,20 +95,20 @@ static void xor_block(unsigned char const *in, unsigned char *out)
static int _get_more_prng_bytes(struct prng_context *ctx, bool cont_test)
{
int i;
- unsigned char tmp[DEFAULT_BLK_SZ];
+ union block tmp;
dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
ctx);
- hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
- hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
+ hexdump("Input DT: ", &ctx->DT);
+ hexdump("Input V: ", &ctx->V);
/*
* Start by encrypting the counter value.
* This gives us an intermediate value I.
*/
- crypto_cipher_encrypt_one(ctx->tfm, tmp, ctx->DT);
- hexdump("input I: ", tmp, DEFAULT_BLK_SZ);
+ crypto_cipher_encrypt_one(ctx->tfm, tmp.bytes, ctx->DT.bytes);
+ hexdump("input I: ", &tmp);
/*
* Next xor I with our secret vector V.
@@ -106,15 +116,15 @@ static int _get_more_prng_bytes(struct prng_context *ctx, bool cont_test)
* we output. It is kept temporarily in (no longer used)
* V until we have done the anti-repetition compare.
*/
- xor_block(tmp, ctx->V);
- hexdump("input stage 1: ", ctx->V, DEFAULT_BLK_SZ);
- crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V);
+ xor_block(&tmp, &ctx->V);
+ hexdump("input stage 1: ", &ctx->V);
+ crypto_cipher_encrypt_one(ctx->tfm, ctx->V.bytes, ctx->V.bytes);
/*
* Check that we didn't produce the same random data
* that we did last time around.
*/
- if (!memcmp(ctx->V, ctx->rand_data, DEFAULT_BLK_SZ)) {
+ if (!memcmp(ctx->V.bytes, ctx->rand_data.bytes, DEFAULT_BLK_SZ)) {
if (cont_test) {
panic("cprng %p Failed repetition check!\n", ctx);
}
@@ -123,30 +133,30 @@ static int _get_more_prng_bytes(struct prng_context *ctx, bool cont_test)
ctx->flags |= PRNG_NEED_RESET;
return -EINVAL;
}
- memcpy(ctx->rand_data, ctx->V, DEFAULT_BLK_SZ);
+ ctx->rand_data = ctx->V;
/*
* Lastly xor the random data with I and encrypt that to
* obtain a new secret vector V
*/
- xor_block(tmp, ctx->V);
- hexdump("input stage 2: ", ctx->V, DEFAULT_BLK_SZ);
- crypto_cipher_encrypt_one(ctx->tfm, ctx->V, ctx->V);
+ xor_block(&tmp, &ctx->V);
+ hexdump("input stage 2: ", &ctx->V);
+ crypto_cipher_encrypt_one(ctx->tfm, ctx->V.bytes, ctx->V.bytes);
/*
* Now update our DT value
*/
for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
- ctx->DT[i] += 1;
- if (ctx->DT[i] != 0)
+ ctx->DT.bytes[i] += 1;
+ if (ctx->DT.bytes[i] != 0)
break;
}
dbgprint("Returning new block for context %p\n", ctx);
- hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
- hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
- hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
+ hexdump("Output DT: ", &ctx->DT);
+ hexdump("Output V: ", &ctx->V);
+ hexdump("New Random Data: ", &ctx->rand_data);
return 0;
}
@@ -171,7 +181,7 @@ static int get_prng_bytes(unsigned char *buf, unsigned int nbytes,
while (nbytes - pos > DEFAULT_BLK_SZ - read_pos) {
len = DEFAULT_BLK_SZ - read_pos;
- memcpy(buf + pos, ctx->rand_data + read_pos, len);
+ memcpy(buf + pos, ctx->rand_data.bytes + read_pos, len);
if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
memset(buf, 0, nbytes);
goto done;
@@ -182,7 +192,7 @@ static int get_prng_bytes(unsigned char *buf, unsigned int nbytes,
/* The final partial block */
len = nbytes - pos;
- memcpy(buf + pos, ctx->rand_data + read_pos, len);
+ memcpy(buf + pos, ctx->rand_data.bytes + read_pos, len);
ctx->rand_read_pos = read_pos + len;
err = nbytes;
@@ -207,14 +217,14 @@ static int reset_prng_context(struct prng_context *ctx,
spin_lock_bh(&ctx->prng_lock);
ctx->flags |= PRNG_NEED_RESET;
- memcpy(ctx->V, V, DEFAULT_BLK_SZ);
+ memcpy(ctx->V.bytes, V, DEFAULT_BLK_SZ);
if (DT)
- memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
+ memcpy(ctx->DT.bytes, DT, DEFAULT_BLK_SZ);
else
- memset(ctx->DT, 0, DEFAULT_BLK_SZ);
+ memset(ctx->DT.bytes, 0, DEFAULT_BLK_SZ);
- memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
+ memset(ctx->rand_data.bytes, 0, DEFAULT_BLK_SZ);
ctx->rand_read_pos = DEFAULT_BLK_SZ; /* Force immediate refill */
--
2.1.3
--
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