On Thu, 30 May 2019 at 16:27, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > > On Thu, May 30, 2019 at 03:55:07PM +0200, Ard Biesheuvel wrote: > > > > > Would this work? > > I see. You need to preserve the original IV. > > > > diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c > > > index c0ece44f303b..2ef2f76a3cb8 100644 > > > --- a/drivers/crypto/caam/caamalg.c > > > +++ b/drivers/crypto/caam/caamalg.c > > > @@ -1832,22 +1832,25 @@ static int skcipher_decrypt(struct > > > skcipher_request *req) > > > struct caam_ctx *ctx = crypto_skcipher_ctx(skcipher); > > > int ivsize = crypto_skcipher_ivsize(skcipher); > > > struct device *jrdev = ctx->jrdev; > > > + u8 out_iv[AES_BLOCK_SIZE]; > > > u32 *desc; > > > int ret = 0; > > > > > > - /* allocate extended descriptor */ > > > - edesc = skcipher_edesc_alloc(req, DESC_JOB_IO_LEN * CAAM_CMD_SZ); > > > - if (IS_ERR(edesc)) > > > - return PTR_ERR(edesc); > > > - > > > /* > > > * The crypto API expects us to set the IV (req->iv) to the last > > > * ciphertext block. > > > */ > > > if (ivsize) > > > - scatterwalk_map_and_copy(req->iv, req->src, req->cryptlen - > > > + scatterwalk_map_and_copy(out_iv, req->src, req->cryptlen - > > > ivsize, ivsize, 0); > > > > > > + /* allocate extended descriptor */ > > > + edesc = skcipher_edesc_alloc(req, DESC_JOB_IO_LEN * CAAM_CMD_SZ); > > > + if (IS_ERR(edesc)) > > > + return PTR_ERR(edesc); > > > + > > > + memcpy(req->iv, out_iv, ivsize); > > > + > > > /* Create and submit job descriptor*/ > > > init_skcipher_job(req, edesc, false); > > > desc = edesc->hw_desc; > > > > Umm never mind > > > > /me hides in shame > > So why doesn't this work? > Because the memcpy() occurs while the buffer is mapped for DMA, so it suffers from the exact same problem.
