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random: improve variable naming, clear extract buffer 

- split the SHA variables apart into hash and workspace
- rename data to extract
- wipe extract and workspace after hashing

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Mackall 2008-04-29 01:02:59 -07:00 committed by Linus Torvalds
parent 53c3f63e82
commit ffd8d3fa58
1 changed files with 13 additions and 11 deletions
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24
drivers/char/random.c
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@ -765,9 +765,9 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
static void extract_buf(struct entropy_store *r, __u8 *out) static void extract_buf(struct entropy_store *r, __u8 *out)
{ {
int i; int i;
__u32 data[16], buf[5 + SHA_WORKSPACE_WORDS]; __u32 extract[16], hash[5], workspace[SHA_WORKSPACE_WORDS];
sha_init(buf); sha_init(hash);
/* /*
* As we hash the pool, we mix intermediate values of * As we hash the pool, we mix intermediate values of
* the hash back into the pool. This eliminates * the hash back into the pool. This eliminates
@ -778,9 +778,9 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
*/ */
for (i = 0; i < r->poolinfo->poolwords; i += 16) { for (i = 0; i < r->poolinfo->poolwords; i += 16) {
/* hash blocks of 16 words = 512 bits */ /* hash blocks of 16 words = 512 bits */
sha_transform(buf, (__u8 *)(r->pool + i), buf + 5); sha_transform(hash, (__u8 *)(r->pool + i), workspace);
/* feed back portion of the resulting hash */ /* feed back portion of the resulting hash */
add_entropy_words(r, &buf[i % 5], 1); add_entropy_words(r, &hash[i % 5], 1);
} }
/* /*
@ -788,19 +788,21 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
* portion of the pool while mixing, and hash one * portion of the pool while mixing, and hash one
* final time. * final time.
*/ */
__add_entropy_words(r, &buf[i % 5], 1, data); __add_entropy_words(r, &hash[i % 5], 1, extract);
sha_transform(buf, (__u8 *)data, buf + 5); sha_transform(hash, (__u8 *)extract, workspace);
memset(extract, 0, sizeof(extract));
memset(workspace, 0, sizeof(workspace));
/* /*
* In case the hash function has some recognizable * In case the hash function has some recognizable
* output pattern, we fold it in half. * output pattern, we fold it in half.
*/ */
buf[0] ^= buf[3]; hash[0] ^= hash[3];
buf[1] ^= buf[4]; hash[1] ^= hash[4];
buf[2] ^= rol32(buf[2], 16); hash[2] ^= rol32(hash[2], 16);
memcpy(out, buf, EXTRACT_SIZE); memcpy(out, hash, EXTRACT_SIZE);
memset(buf, 0, sizeof(buf)); memset(hash, 0, sizeof(hash));
} }
static ssize_t extract_entropy(struct entropy_store *r, void *buf, static ssize_t extract_entropy(struct entropy_store *r, void *buf,