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Subject[PATCH] treewide: Update sha_transform
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Date
Move the workspace into sha_transform as local stack variable struct.

Remove #define SHA_WORKSPACE_WORDS.
Remove workspace argument from sha_transform.
Convert uses of __u8 * to void * in sha_transform.
Eliminate possible sha_transform unaligned accesses to data by copying
data to an aligned __u32 array if necessary.
Add sha_transform wipe argument to force workspace clearing if desired.
A little macro neatening.

This should speed network syncookies a trivial bit.

Add #include <linux/cryptohash.h> to lib/sha1.c

Compiled/untested.

Signed-off-by: Joe Perches <joe@perches.com>
---
On Mon, 2011-08-08 at 22:52 -0700, Mandeep Singh Baines wrote:
> We don't call sha_tranform directly. We use crypto_hash_digest. So maybe
> add a wipe param there. I'm happy to work on or test such a patch if folks
> think its interesting. Its saves me 190 ms on a 6 second boot. I suspect
> there may be other hash intense applications that also don't need secracy.

Well, here's the patch I produced.

crypto/sha1_generic.c | 5 +---
drivers/char/random.c | 7 ++---
include/linux/cryptohash.h | 3 +-
lib/sha1.c | 61 +++++++++++++++++++++++++++++++-------------
net/ipv4/syncookies.c | 5 +--
net/ipv4/tcp_output.c | 6 +---
net/ipv6/syncookies.c | 5 +--
7 files changed, 54 insertions(+), 38 deletions(-)
diff --git a/crypto/sha1_generic.c b/crypto/sha1_generic.c
index 00ae60e..d0c3f4a 100644
--- a/crypto/sha1_generic.c
+++ b/crypto/sha1_generic.c
@@ -49,8 +49,6 @@ static int sha1_update(struct shash_desc *desc, const u8 *data,
src = data;

if ((partial + len) >= SHA1_BLOCK_SIZE) {
- u32 temp[SHA_WORKSPACE_WORDS];
-
if (partial) {
done = -partial;
memcpy(sctx->buffer + partial, data,
@@ -59,12 +57,11 @@ static int sha1_update(struct shash_desc *desc, const u8 *data,
}

do {
- sha_transform(sctx->state, src, temp);
+ sha_transform(sctx->state, src, true);
done += SHA1_BLOCK_SIZE;
src = data + done;
} while (done + SHA1_BLOCK_SIZE <= len);

- memset(temp, 0, sizeof(temp));
partial = 0;
}
memcpy(sctx->buffer + partial, src, len - done);
diff --git a/drivers/char/random.c b/drivers/char/random.c
index c35a785..6b9e5dc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -816,13 +816,13 @@ 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 hash[5], workspace[SHA_WORKSPACE_WORDS];
+ __u32 hash[5];
__u8 extract[64];

/* Generate a hash across the pool, 16 words (512 bits) at a time */
sha_init(hash);
for (i = 0; i < r->poolinfo->poolwords; i += 16)
- sha_transform(hash, (__u8 *)(r->pool + i), workspace);
+ sha_transform(hash, r->pool + i, false);

/*
* We mix the hash back into the pool to prevent backtracking
@@ -839,9 +839,8 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
* To avoid duplicates, we atomically extract a portion of the
* pool while mixing, and hash one final time.
*/
- sha_transform(hash, extract, workspace);
+ sha_transform(hash, extract, true);
memset(extract, 0, sizeof(extract));
- memset(workspace, 0, sizeof(workspace));

/*
* In case the hash function has some recognizable output
diff --git a/include/linux/cryptohash.h b/include/linux/cryptohash.h
index 2cd9f1c..c64b5cf 100644
--- a/include/linux/cryptohash.h
+++ b/include/linux/cryptohash.h
@@ -3,10 +3,9 @@

#define SHA_DIGEST_WORDS 5
#define SHA_MESSAGE_BYTES (512 /*bits*/ / 8)
-#define SHA_WORKSPACE_WORDS 16

void sha_init(__u32 *buf);
-void sha_transform(__u32 *digest, const char *data, __u32 *W);
+void sha_transform(__u32 *digest, const void *data, bool wipe);

#define MD5_DIGEST_WORDS 4
#define MD5_MESSAGE_BYTES 64
diff --git a/lib/sha1.c b/lib/sha1.c
index f33271d..a78ca29 100644
--- a/lib/sha1.c
+++ b/lib/sha1.c
@@ -8,6 +8,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bitops.h>
+#include <linux/cryptohash.h>
#include <asm/unaligned.h>

/*
@@ -41,45 +42,66 @@
#endif

/* This "rolls" over the 512-bit array */
-#define W(x) (array[(x)&15])
+#define W(x) (workspace.array[(x)&15])

/*
* Where do we get the source from? The first 16 iterations get it from
* the input data, the next mix it from the 512-bit array.
*/
-#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
+#define SHA_SRC(t) (workspace.aligned_data[t])
#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)

-#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
- __u32 TEMP = input(t); setW(t, TEMP); \
- E += TEMP + rol32(A,5) + (fn) + (constant); \
- B = ror32(B, 2); } while (0)
-
-#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
-#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
-#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
-#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
-#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
+#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) \
+do { \
+ __u32 TEMP = input(t); \
+ \
+ setW(t, TEMP); \
+ E += TEMP + rol32(A, 5) + (fn) + (constant); \
+ B = ror32(B, 2); \
+} while (0)
+
+#define T_0_15(t, A, B, C, D, E) \
+ SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D), 0x5a827999, A, B, C, D, E)
+#define T_16_19(t, A, B, C, D, E) \
+ SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D), 0x5a827999, A, B, C, D, E)
+#define T_20_39(t, A, B, C, D, E) \
+ SHA_ROUND(t, SHA_MIX, (B^C^D), 0x6ed9eba1, A, B, C, D, E)
+#define T_40_59(t, A, B, C, D, E) \
+ SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))), 0x8f1bbcdc, A, B, C, D, E)
+#define T_60_79(t, A, B, C, D, E) \
+ SHA_ROUND(t, SHA_MIX, (B^C^D), 0xca62c1d6, A, B, C, D, E)

/**
* sha_transform - single block SHA1 transform
*
* @digest: 160 bit digest to update
* @data: 512 bits of data to hash
- * @array: 16 words of workspace (see note)
+ * @wipe: true if the hash is security sensitive
*
* This function generates a SHA1 digest for a single 512-bit block.
* Be warned, it does not handle padding and message digest, do not
* confuse it with the full FIPS 180-1 digest algorithm for variable
* length messages.
- *
- * Note: If the hash is security sensitive, the caller should be sure
- * to clear the workspace. This is left to the caller to avoid
- * unnecessary clears between chained hashing operations.
*/
-void sha_transform(__u32 *digest, const char *data, __u32 *array)
+void sha_transform(__u32 *digest, const void *data, bool wipe)
{
__u32 A, B, C, D, E;
+ struct {
+ __u32 array[16]; /* working array */
+ __u32 aligned[16]; /* u32 aligned version of data */
+ const __u32 *aligned_data; /* either data or aligned */
+ } workspace;
+ size_t wipe_size;
+
+ if (((unsigned long)data) & 3) { /* unaligned word accesses */
+ workspace.aligned_data =
+ memcpy(workspace.aligned, data,
+ sizeof(workspace.aligned));
+ wipe_size = sizeof(workspace);
+ } else {
+ workspace.aligned_data = data;
+ wipe_size = sizeof(workspace.array);
+ }

A = digest[0];
B = digest[1];
@@ -182,6 +204,9 @@ void sha_transform(__u32 *digest, const char *data, __u32 *array)
digest[2] += C;
digest[3] += D;
digest[4] += E;
+
+ if (wipe)
+ memset(&workspace, 0, wipe_size);
}
EXPORT_SYMBOL(sha_transform);

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 92bb943..8f429cd 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -37,8 +37,7 @@ __initcall(init_syncookies);
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)

-static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
- ipv4_cookie_scratch);
+static DEFINE_PER_CPU(__u32 [16 + 5], ipv4_cookie_scratch);

static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
u32 count, int c)
@@ -50,7 +49,7 @@ static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
tmp[1] = (__force u32)daddr;
tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
tmp[3] = count;
- sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5);
+ sha_transform(tmp + 16, tmp, false);

return tmp[17];
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 882e0b0..454ed67 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2494,7 +2494,6 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
}

if (opts.hash_size > 0) {
- __u32 workspace[SHA_WORKSPACE_WORDS];
u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS];
u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1];

@@ -2510,9 +2509,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
*tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source);
*tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */

- sha_transform((__u32 *)&xvp->cookie_bakery[0],
- (char *)mess,
- &workspace[0]);
+ sha_transform((__u32 *)&xvp->cookie_bakery[0], mess,
+ false);
opts.hash_location =
(__u8 *)&xvp->cookie_bakery[0];
}
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 89d5bf8..90823e0 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -63,8 +63,7 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
return child;
}

-static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
- ipv6_cookie_scratch);
+static DEFINE_PER_CPU(__u32 [16 + 5], ipv6_cookie_scratch);

static u32 cookie_hash(const struct in6_addr *saddr, const struct in6_addr *daddr,
__be16 sport, __be16 dport, u32 count, int c)
@@ -81,7 +80,7 @@ static u32 cookie_hash(const struct in6_addr *saddr, const struct in6_addr *dadd
memcpy(tmp + 4, daddr, 16);
tmp[8] = ((__force u32)sport << 16) + (__force u32)dport;
tmp[9] = count;
- sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5);
+ sha_transform(tmp + 16, tmp, false);

return tmp[17];
}
--
1.7.6.405.gc1be0




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