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crypto: rsa-pkcs1pad - Handle leading zero for decryption

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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: 9b45b7bba3d2 ("crypto: rsa - Generate fixed-length output")
Reported-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2016-09-22 17:04:57 +08:00
parent 456bee986e
commit 0cf43f509f
1 changed files with 24 additions and 17 deletions
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41
crypto/rsa-pkcs1pad.c
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@ -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);