From d858b0713849be51406fe84722d0877fb57d201c Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Wed, 29 Jun 2016 19:32:28 +0800 Subject: [PATCH] crypto: rsa-pkcs1pad - Avoid copying output when possible In the vast majority of cases (2^-32 on 32-bit and 2^-64 on 64-bit) cases, the result from encryption/signing will require no padding. This patch makes these two operations write their output directly to the final destination. Only in the exceedingly rare cases where fixup is needed to we copy it out and back to add the leading zeroes. This patch also makes use of the crypto_akcipher_set_crypt API instead of writing the akcipher request directly. Signed-off-by: Herbert Xu --- crypto/rsa-pkcs1pad.c | 112 +++++++++++++++++------------------------- 1 file changed, 45 insertions(+), 67 deletions(-) diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c index ebd851474a9d..8ccfdd7c926e 100644 --- a/crypto/rsa-pkcs1pad.c +++ b/crypto/rsa-pkcs1pad.c @@ -185,37 +185,36 @@ static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err) struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req); struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm); struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req); - size_t pad_len = ctx->key_size - req_ctx->child_req.dst_len; - size_t chunk_len, pad_left; - struct sg_mapping_iter miter; - - if (!err) { - if (pad_len) { - sg_miter_start(&miter, req->dst, - sg_nents_for_len(req->dst, pad_len), - SG_MITER_ATOMIC | SG_MITER_TO_SG); - - pad_left = pad_len; - while (pad_left) { - sg_miter_next(&miter); - - chunk_len = min(miter.length, pad_left); - memset(miter.addr, 0, chunk_len); - pad_left -= chunk_len; - } - - sg_miter_stop(&miter); - } - - sg_pcopy_from_buffer(req->dst, - sg_nents_for_len(req->dst, ctx->key_size), - req_ctx->out_buf, req_ctx->child_req.dst_len, - pad_len); - } + unsigned int pad_len; + unsigned int len; + u8 *out_buf; + + if (err) + goto out; + + len = req_ctx->child_req.dst_len; + pad_len = ctx->key_size - len; + + /* Four billion to one */ + if (likely(!pad_len)) + goto out; + + out_buf = kzalloc(ctx->key_size, GFP_ATOMIC); + err = -ENOMEM; + if (!out_buf) + goto out; + + sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len), + out_buf + pad_len, len); + sg_copy_from_buffer(req->dst, + sg_nents_for_len(req->dst, ctx->key_size), + out_buf, ctx->key_size); + kzfree(out_buf); + +out: req->dst_len = ctx->key_size; kfree(req_ctx->in_buf); - kzfree(req_ctx->out_buf); return err; } @@ -255,15 +254,6 @@ static int pkcs1pad_encrypt(struct akcipher_request *req) return -EOVERFLOW; } - /* - * Replace both input and output to add the padding in the input and - * the potential missing leading zeros in the output. - */ - req_ctx->child_req.src = req_ctx->in_sg; - req_ctx->child_req.src_len = ctx->key_size - 1; - req_ctx->child_req.dst = req_ctx->out_sg; - req_ctx->child_req.dst_len = ctx->key_size; - req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len, GFP_KERNEL); if (!req_ctx->in_buf) @@ -291,6 +281,10 @@ static int pkcs1pad_encrypt(struct akcipher_request *req) akcipher_request_set_callback(&req_ctx->child_req, req->base.flags, pkcs1pad_encrypt_sign_complete_cb, req); + /* Reuse output buffer */ + akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, + req->dst, ctx->key_size - 1, req->dst_len); + err = crypto_akcipher_encrypt(&req_ctx->child_req); if (err != -EINPROGRESS && (err != -EBUSY || @@ -372,12 +366,6 @@ static int pkcs1pad_decrypt(struct akcipher_request *req) if (!ctx->key_size || req->src_len != ctx->key_size) return -EINVAL; - /* Reuse input buffer, output to a new buffer */ - req_ctx->child_req.src = req->src; - req_ctx->child_req.src_len = req->src_len; - req_ctx->child_req.dst = req_ctx->out_sg; - req_ctx->child_req.dst_len = ctx->key_size ; - req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL); if (!req_ctx->out_buf) return -ENOMEM; @@ -389,6 +377,11 @@ static int pkcs1pad_decrypt(struct akcipher_request *req) akcipher_request_set_callback(&req_ctx->child_req, req->base.flags, pkcs1pad_decrypt_complete_cb, req); + /* Reuse input buffer, output to a new buffer */ + akcipher_request_set_crypt(&req_ctx->child_req, req->src, + req_ctx->out_sg, req->src_len, + ctx->key_size); + err = crypto_akcipher_decrypt(&req_ctx->child_req); if (err != -EINPROGRESS && (err != -EBUSY || @@ -422,15 +415,6 @@ static int pkcs1pad_sign(struct akcipher_request *req) return -EOVERFLOW; } - /* - * Replace both input and output to add the padding in the input and - * the potential missing leading zeros in the output. - */ - req_ctx->child_req.src = req_ctx->in_sg; - req_ctx->child_req.src_len = ctx->key_size - 1; - req_ctx->child_req.dst = req_ctx->out_sg; - req_ctx->child_req.dst_len = ctx->key_size; - req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len, GFP_KERNEL); if (!req_ctx->in_buf) @@ -447,19 +431,14 @@ static int pkcs1pad_sign(struct akcipher_request *req) pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf, ctx->key_size - 1 - req->src_len, req->src); - req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL); - if (!req_ctx->out_buf) { - kfree(req_ctx->in_buf); - return -ENOMEM; - } - - pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf, - ctx->key_size, NULL); - akcipher_request_set_tfm(&req_ctx->child_req, ctx->child); akcipher_request_set_callback(&req_ctx->child_req, req->base.flags, pkcs1pad_encrypt_sign_complete_cb, req); + /* Reuse output buffer */ + akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, + req->dst, ctx->key_size - 1, req->dst_len); + err = crypto_akcipher_sign(&req_ctx->child_req); if (err != -EINPROGRESS && (err != -EBUSY || @@ -559,12 +538,6 @@ static int pkcs1pad_verify(struct akcipher_request *req) if (!ctx->key_size || req->src_len < ctx->key_size) return -EINVAL; - /* Reuse input buffer, output to a new buffer */ - req_ctx->child_req.src = req->src; - req_ctx->child_req.src_len = req->src_len; - req_ctx->child_req.dst = req_ctx->out_sg; - req_ctx->child_req.dst_len = ctx->key_size; - req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL); if (!req_ctx->out_buf) return -ENOMEM; @@ -576,6 +549,11 @@ static int pkcs1pad_verify(struct akcipher_request *req) akcipher_request_set_callback(&req_ctx->child_req, req->base.flags, pkcs1pad_verify_complete_cb, req); + /* Reuse input buffer, output to a new buffer */ + akcipher_request_set_crypt(&req_ctx->child_req, req->src, + req_ctx->out_sg, req->src_len, + ctx->key_size); + err = crypto_akcipher_verify(&req_ctx->child_req); if (err != -EINPROGRESS && (err != -EBUSY || -- 2.20.1