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crypto: vmac - Make VMAC work when blocks aren't aligned

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VMAC implementation, as it is, does not work with blocks that
are not multiples of 128-bytes.  Furthermore, this is a problem
when using the implementation on scatterlists, even
when the complete plain text is 128-byte multiple, as the pieces
that get passed to vmac_update can be pretty much any size.

I also added test cases for unaligned blocks.

Signed-off-by: Salman Qazi <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
This commit is contained in:
Salman Qazi 2012-10-05 14:24:14 -07:00 • committed by Herbert Xu
commit ba1ee07090
3 changed files with 77 additions and 5 deletions
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47
crypto/vmac.c
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@ -375,6 +375,11 @@ static void vhash_update(const unsigned char *m,
u64 pkh = ctx->polykey[0];
u64 pkl = ctx->polykey[1];
if (!mbytes)
return;
BUG_ON(mbytes % VMAC_NHBYTES);
mptr = (u64 *)m;
i = mbytes / VMAC_NHBYTES; /* Must be non-zero */
@ -454,7 +459,7 @@ do_l3:
}
static u64 vmac(unsigned char m[], unsigned int mbytes,
unsigned char n[16], u64 *tagl,
const unsigned char n[16], u64 *tagl,
struct vmac_ctx_t *ctx)
{
u64 *in_n, *out_p;
@ -559,8 +564,33 @@ static int vmac_update(struct shash_desc *pdesc, const u8 *p,
{
struct crypto_shash *parent = pdesc->tfm;
struct vmac_ctx_t *ctx = crypto_shash_ctx(parent);
int expand;
int min;
vhash_update(p, len, &ctx->__vmac_ctx);
expand = VMAC_NHBYTES - ctx->partial_size > 0 ?
VMAC_NHBYTES - ctx->partial_size : 0;
min = len < expand ? len : expand;
memcpy(ctx->partial + ctx->partial_size, p, min);
ctx->partial_size += min;
if (len < expand)
return 0;
vhash_update(ctx->partial, VMAC_NHBYTES, &ctx->__vmac_ctx);
ctx->partial_size = 0;
len -= expand;
p += expand;
if (len % VMAC_NHBYTES) {
memcpy(ctx->partial, p + len - (len % VMAC_NHBYTES),
len % VMAC_NHBYTES);
ctx->partial_size = len % VMAC_NHBYTES;
}
vhash_update(p, len - len % VMAC_NHBYTES, &ctx->__vmac_ctx);
return 0;
}
@ -572,10 +602,20 @@ static int vmac_final(struct shash_desc *pdesc, u8 *out)
vmac_t mac;
u8 nonce[16] = {};
mac = vmac(NULL, 0, nonce, NULL, ctx);
/* vmac() ends up accessing outside the array bounds that
* we specify. In appears to access up to the next 2-word
* boundary. We'll just be uber cautious and zero the
* unwritten bytes in the buffer.
*/
if (ctx->partial_size) {
memset(ctx->partial + ctx->partial_size, 0,
VMAC_NHBYTES - ctx->partial_size);
}
mac = vmac(ctx->partial, ctx->partial_size, nonce, NULL, ctx);
memcpy(out, &mac, sizeof(vmac_t));
memset(&mac, 0, sizeof(vmac_t));
memset(&ctx->__vmac_ctx, 0, sizeof(struct vmac_ctx));
ctx->partial_size = 0;
return 0;
}
@ -673,4 +713,3 @@ module_exit(vmac_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("VMAC hash algorithm");