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net: phy: mscc: avoid skcipher API for single block AES encryption 

The skcipher API dynamically instantiates the transformation object
on request that implements the requested algorithm optimally on the
given platform. This notion of optimality only matters for cases like
bulk network or disk encryption, where performance can be a bottleneck,
or in cases where the algorithm itself is not known at compile time.

In the mscc case, we are dealing with AES encryption of a single
block, and so neither concern applies, and we are better off using
the AES library interface, which is lightweight and safe for this
kind of use.

Note that the scatterlist API does not permit references to buffers
that are located on the stack, so the existing code is incorrect in
any case, but avoiding the skcipher and scatterlist APIs entirely is
the most straight-forward approach to fixing this.

Cc: Antoine Tenart <antoine.tenart@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Fixes: 28c5107aa9 ("net: phy: mscc: macsec support")
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ard Biesheuvel 2020-06-25 09:18:16 +02:00 committed by David S. Miller
parent eb2932b00f
commit 5a3235e50c
2 changed files with 10 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/phy/Kconfig
View File

@ -480,8 +480,7 @@ config MICROCHIP_T1_PHY
config MICROSEMI_PHY
tristate "Microsemi PHYs"
depends on MACSEC || MACSEC=n
select CRYPTO_AES
select CRYPTO_ECB
select CRYPTO_LIB_AES if MACSEC
help
Currently supports VSC8514, VSC8530, VSC8531, VSC8540 and VSC8541 PHYs

40
drivers/net/phy/mscc/mscc_macsec.c
View File

@ -10,7 +10,7 @@
#include <linux/phy.h>
#include <dt-bindings/net/mscc-phy-vsc8531.h>
#include <crypto/skcipher.h>
#include <crypto/aes.h>
#include <net/macsec.h>
@ -500,39 +500,17 @@ static u32 vsc8584_macsec_flow_context_id(struct macsec_flow *flow)
static int vsc8584_macsec_derive_key(const u8 key[MACSEC_KEYID_LEN],
u16 key_len, u8 hkey[16])
{
struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
struct skcipher_request *req = NULL;
struct scatterlist src, dst;
DECLARE_CRYPTO_WAIT(wait);
u32 input[4] = {0};
const u8 input[AES_BLOCK_SIZE] = {0};
struct crypto_aes_ctx ctx;
int ret;
if (IS_ERR(tfm))
return PTR_ERR(tfm);
ret = aes_expandkey(&ctx, key, key_len);
if (ret)
return ret;
req = skcipher_request_alloc(tfm, GFP_KERNEL);
if (!req) {
ret = -ENOMEM;
goto out;
}
skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP, crypto_req_done,
&wait);
ret = crypto_skcipher_setkey(tfm, key, key_len);
if (ret < 0)
goto out;
sg_init_one(&src, input, 16);
sg_init_one(&dst, hkey, 16);
skcipher_request_set_crypt(req, &src, &dst, 16, NULL);
ret = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
out:
skcipher_request_free(req);
crypto_free_skcipher(tfm);
return ret;
aes_encrypt(&ctx, hkey, input);
memzero_explicit(&ctx, sizeof(ctx));
return 0;
}
static int vsc8584_macsec_transformation(struct phy_device *phydev,