On Tue, Jun 11, 2019 at 03:47:50PM +0200, Ard Biesheuvel wrote:
> The CIFS code uses the sync skcipher API to invoke the ecb(arc4) skcipher,
> of which only a single generic C code implementation exists. This means
> that going through all the trouble of using scatterlists etc buys us
> very little, and we're better off just invoking the arc4 library directly.
>
> Cc: linux-cifs@xxxxxxxxxxxxxxx
> Cc: Steve French <sfrench@xxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> fs/cifs/Kconfig | 2 +-
> fs/cifs/cifsencrypt.c | 53 ++++++--------------
> 2 files changed, 16 insertions(+), 39 deletions(-)
>
> diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
> index aae2b8b2adf5..523e9ea78a28 100644
> --- a/fs/cifs/Kconfig
> +++ b/fs/cifs/Kconfig
> @@ -10,7 +10,7 @@ config CIFS
> select CRYPTO_SHA512
> select CRYPTO_CMAC
> select CRYPTO_HMAC
> - select CRYPTO_ARC4
> + select CRYPTO_LIB_ARC4
> select CRYPTO_AEAD2
> select CRYPTO_CCM
> select CRYPTO_ECB
Since the "arc4" module is no longer needed, the
MODULE_SOFTDEP("pre: arc4");
in fs/cifs/cifsfs.c should be removed too.
(Note that it doesn't need a soft dependency on libarc4 instead, since the cifs
module will link directly to it.)
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index d2a05e46d6f5..3b7b5e83493d 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -33,7 +33,8 @@
> #include <linux/ctype.h>
> #include <linux/random.h>
> #include <linux/highmem.h>
> -#include <crypto/skcipher.h>
> +#include <linux/fips.h>
> +#include <crypto/arc4.h>
> #include <crypto/aead.h>
>
> int __cifs_calc_signature(struct smb_rqst *rqst,
> @@ -772,11 +773,12 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
> int
> calc_seckey(struct cifs_ses *ses)
> {
> - int rc;
> - struct crypto_skcipher *tfm_arc4;
> - struct scatterlist sgin, sgout;
> - struct skcipher_request *req;
> + struct arc4_ctx *ctx_arc4;
> unsigned char *sec_key;
> + int rc = 0;
> +
> + if (fips_enabled)
> + return -ENODEV;
>
> sec_key = kmalloc(CIFS_SESS_KEY_SIZE, GFP_KERNEL);
> if (sec_key == NULL)
sec_key should be moved back to the stack now, basically reverting this commit:
commit 5f4b55699aaff1028468e3f53853d781cdafedd6
Author: Sachin Prabhu <sprabhu@xxxxxxxxxx>
Date: Mon Oct 17 16:40:22 2016 -0400
CIFS: Fix BUG() in calc_seckey()
It was only moved to the heap because it had to go in a scatterlist.
> + arc4_setkey(ctx_arc4, ses->auth_key.response, CIFS_SESS_KEY_SIZE);
> + arc4_crypt(ctx_arc4, ses->ntlmssp->ciphertext, sec_key,
> + CIFS_CPHTXT_SIZE);
>
> /* make secondary_key/nonce as session key */
> memcpy(ses->auth_key.response, sec_key, CIFS_SESS_KEY_SIZE);
> /* and make len as that of session key only */
> ses->auth_key.len = CIFS_SESS_KEY_SIZE;
>
> -out_free_cipher:
> - crypto_free_skcipher(tfm_arc4);
> out:
> + kfree(ctx_arc4);
Should be kzfree().
- Eric
