Attachment 316380 Details for Bug 461537 – [CRYPTO] hmac: Avoid calling virt_to_page on key

[patch] [CRYPTO] hmac: Avoid calling virt_to_page on key

p (text/plain), 1.53 KB, created by Herbert Xu on 2008-09-11 00:43:08 UTC

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Creator: Herbert Xu

Created: 2008-09-11 00:43:08 UTC

Size: 1.53 KB

patch

obsolete

>commit 5492ac24ac216f0227aad356e753ce0471c69fd6
>Author: Herbert Xu <herbert@gondor.apana.org.au>
>Date:   Thu Sep 11 10:42:31 2008 +1000
>
>    [CRYPTO] hmac: Avoid calling virt_to_page on key
>    
>    When HMAC gets a key longer than the block size of the hash, it needs
>    to feed it as input to the hash to reduce it to a fixed length.  As
>    it is HMAC converts the key to a scatter and gather list.  However,
>    this doesn't work on certain platforms if the key is not allocated
>    via kmalloc.  For example, the keys from tcrypt are stored in the
>    rodata section and this causes it to fail with HMAC on x86-64.
>    
>    This patch fixes this by copying the key to memory obtained via
>    kmalloc before hashing it.
>    
>    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
>diff --git a/crypto/hmac.c b/crypto/hmac.c
>index 28a713b..a2faf9d 100644
>--- a/crypto/hmac.c
>+++ b/crypto/hmac.c
>@@ -56,9 +56,25 @@ static int hmac_setkey(struct crypto_hash *parent,
> 
> 	if (keylen > bs) {
> 		struct scatterlist tmp;
>+		int tmplen;
> 
>-		sg_init_one(&tmp, (u8 *)inkey, keylen);
>-		crypto_digest_digest(tfm, &tmp, 1, digest);
>+		crypto_digest_init(tfm);
>+
>+		tmplen = bs * 2 + ds;
>+		sg_init_one(&tmp, ipad, tmplen);
>+
>+		for (; keylen > tmplen; inkey += tmplen, keylen -= tmplen) {
>+			memcpy(ipad, inkey, tmplen);
>+			crypto_digest_update(tfm, &tmp, 1);
>+		}
>+
>+		if (keylen) {
>+			memcpy(ipad, inkey, keylen);
>+			tmp.length = keylen;
>+			crypto_digest_update(tfm, &tmp, 1);
>+		}
>+
>+		crypto_digest_final(tfm, digest);
> 
> 		inkey = digest;
> 		keylen = ds;

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