Re: [PATCH v6 6/6] crypto: AF_ALG - add support for key_id
From: Mat Martineau <hidden>
Date: 2016-05-26 00:46:09
Also in:
linux-crypto, lkml
On Sat, 14 May 2016, Tadeusz Struk wrote:
quoted hunk ↗ jump to hunk
diff --git a/crypto/algif_akcipher.c b/crypto/algif_akcipher.c index e00793d..6733df1 100644 --- a/crypto/algif_akcipher.c +++ b/crypto/algif_akcipher.c +static int asym_key_verify(const struct key *key, struct akcipher_request *req) +{ + struct public_key_signature sig; + char *src = NULL, *in; + int ret; + + if (!sg_is_last(req->src)) { + src = kmalloc(req->src_len, GFP_KERNEL); + if (!src) + return -ENOMEM; + scatterwalk_map_and_copy(src, req->src, 0, req->src_len, 0); + in = src; + } else { + in = sg_virt(req->src); + } + sig.pkey_algo = "rsa"; + sig.encoding = "pkcs1"; + /* Need to find a way to pass the hash param */
Are you referring to sig.digest here? It looks like you will hit a BUG_ON() in public_key_verify_signature() if sig.digest is 0. However, sig.digest is unlikely to be 0 because the struct is not cleared - should fix this, since public_key_verify_signature() will try to follow that random pointer.
+ sig.hash_algo = "sha1"; + sig.digest_size = 20; + sig.s_size = req->src_len; + sig.s = src; + ret = verify_signature(key, NULL, &sig);
Is the idea to write the signature to the socket, and then read out the expected digest (the digest comparison being done elsewhere)? Is that something that will be supported by a future hardware asymmetric key subtype? verify_signature() ends up calling public_key_verify_signature(), which currently expects to get both the digest and signature as input and returns an error if verification fails. The output of crypto_akcipher_verify() is discarded before public_key_verify_signature() returns so nothing ends up in req->dst to read from the socket. ALG_OP_VERIFY should behave the same whether using ALG_SET_PUBKEY or ALG_SET_PUBKEY_ID, and they aren't right now. If sig.digest is 0, verify_signature() could return the expected digest in the sig structure and skip the digest comparison it currently does. Then that data could be packaged up in req as if crypto_akcipher_verify() had been called. I don't know if this change confuses the semantics of verify_signature() too much, maybe a new function is required with all the requisite plumbing to the asymmetric key subtype.