Commit ffd8d3fa authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
Browse files

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: default avatarMatt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 53c3f63e

drivers/char/random.c

+13 −11
Original line number Diff line number Diff line
@@ -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)

{

	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

	 * 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) {

		/* 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 */

		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

	 * final time.

	 */

	__add_entropy_words(r, &buf[i % 5], 1, data);

	sha_transform(buf, (__u8 *)data, buf + 5);

	__add_entropy_words(r, &hash[i % 5], 1, extract);

	sha_transform(hash, (__u8 *)extract, workspace);

	memset(extract, 0, sizeof(extract));

	memset(workspace, 0, sizeof(workspace));



	/*

	 * In case the hash function has some recognizable

	 * output pattern, we fold it in half.

	 */



	buf[0] ^= buf[3];

	buf[1] ^= buf[4];

	buf[2] ^= rol32(buf[2], 16);

	memcpy(out, buf, EXTRACT_SIZE);

	memset(buf, 0, sizeof(buf));

	hash[0] ^= hash[3];

	hash[1] ^= hash[4];

	hash[2] ^= rol32(hash[2], 16);

	memcpy(out, hash, EXTRACT_SIZE);

	memset(hash, 0, sizeof(hash));

}



static ssize_t extract_entropy(struct entropy_store *r, void *buf,