From 38d20e9265b6677dd840e4ba4ef012a0044948a2 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 22 Sep 2016 17:04:57 +0800 Subject: crypto: rsa-pkcs1pad - Handle leading zero for decryption As the software RSA implementation now produces fixed-length output, we need to eliminate leading zeros in the calling code instead. This patch does just that for pkcs1pad decryption while signature verification was fixed in an earlier patch. Fixes: ebff06f6e2a1 ("crypto: rsa - Generate fixed-length output") Reported-by: Mat Martineau Signed-off-by: Herbert Xu --- crypto/rsa-pkcs1pad.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-) (limited to 'crypto/rsa-pkcs1pad.c') diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c index 877019a6..8baab430 100644 --- a/crypto/rsa-pkcs1pad.c +++ b/crypto/rsa-pkcs1pad.c @@ -298,41 +298,48 @@ static int pkcs1pad_decrypt_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); + unsigned int dst_len; unsigned int pos; - - if (err == -EOVERFLOW) - /* Decrypted value had no leading 0 byte */ - err = -EINVAL; + u8 *out_buf; if (err) goto done; - if (req_ctx->child_req.dst_len != ctx->key_size - 1) { - err = -EINVAL; + err = -EINVAL; + dst_len = req_ctx->child_req.dst_len; + if (dst_len < ctx->key_size - 1) goto done; + + out_buf = req_ctx->out_buf; + if (dst_len == ctx->key_size) { + if (out_buf[0] != 0x00) + /* Decrypted value had no leading 0 byte */ + goto done; + + dst_len--; + out_buf++; } - if (req_ctx->out_buf[0] != 0x02) { - err = -EINVAL; + if (out_buf[0] != 0x02) goto done; - } - for (pos = 1; pos < req_ctx->child_req.dst_len; pos++) - if (req_ctx->out_buf[pos] == 0x00) + + for (pos = 1; pos < dst_len; pos++) + if (out_buf[pos] == 0x00) break; - if (pos < 9 || pos == req_ctx->child_req.dst_len) { - err = -EINVAL; + if (pos < 9 || pos == dst_len) goto done; - } pos++; - if (req->dst_len < req_ctx->child_req.dst_len - pos) + err = 0; + + if (req->dst_len < dst_len - pos) err = -EOVERFLOW; - req->dst_len = req_ctx->child_req.dst_len - pos; + req->dst_len = dst_len - pos; if (!err) sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, req->dst_len), - req_ctx->out_buf + pos, req->dst_len); + out_buf + pos, req->dst_len); done: kzfree(req_ctx->out_buf); -- cgit v1.2.3