From 5f679c36ccb3e125ee6e8372a60d0f2e8bf410fe Mon Sep 17 00:00:00 2001 From: Mark Wooding Date: Sat, 29 Apr 2017 13:55:40 +0100 Subject: [PATCH] Change our view of the Diffie--Hellman closure protocol. Rename `len' to `secret_len' and `ceil_len' to `shared_len', and label these as the required private secret length and generated shared-secret length respectively. There's no functional change: that's what these variables were being used for anyway. Signed-off-by: Mark Wooding --- dh.c | 4 ++-- secnet.h | 18 ++++++++++++++---- site.c | 16 ++++++++-------- 3 files changed, 24 insertions(+), 14 deletions(-) diff --git a/dh.c b/dh.c index 6860bfa..68318ce 100644 --- a/dh.c +++ b/dh.c @@ -154,9 +154,9 @@ static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context, cfgfatal(loc,"diffie-hellman","generator must be less than modulus\n"); } - st->ops.len=sz; + st->ops.secret_len=sz; - st->ops.ceil_len=(mpz_sizeinbase(&st->p,2)+7)/8; + st->ops.shared_len=(mpz_sizeinbase(&st->p,2)+7)/8; /* According to the docs, mpz_sizeinbase(,256) is allowed to return * an answer which is 1 too large. But mpz_sizeinbase(,2) isn't. */ diff --git a/secnet.h b/secnet.h index b23ffa8..731687e 100644 --- a/secnet.h +++ b/secnet.h @@ -612,17 +612,27 @@ struct netlink_if { /* DH interface */ -/* Returns public key as a malloced hex string */ +/* Returns public key as a malloced hex string. The secretlen will be the + * secret_len reported by the closure. This operation is not expected to + * fail. + */ typedef string_t dh_makepublic_fn(void *st, uint8_t *secret, int32_t secretlen); -/* Fills buffer (up to buflen) with shared secret */ + +/* Fills buffer (up to buflen) with shared secret. The rempublic string + * comes from the remote site, and may not be acceptable, though it has been + * checked for memory-safety. The secretlen and buflen are the secret_len + * and shared_len reported by the closure, respectively. Return false on + * faliure (e.g., if the publiclen is unacceptable). + */ typedef bool_t dh_makeshared_fn(void *st, uint8_t *secret, int32_t secretlen, cstring_t rempublic, uint8_t *sharedsecret, int32_t buflen); + struct dh_if { void *st; - int32_t len; /* Approximate size of modulus in bytes */ - int32_t ceil_len; /* Number of bytes just sufficient to contain modulus */ + int32_t secret_len; /* Size of random secret to generate */ + int32_t shared_len; /* Size of generated shared secret */ dh_makepublic_fn *makepublic; dh_makeshared_fn *makeshared; }; diff --git a/site.c b/site.c index 4ac0bab..2ca333b 100644 --- a/site.c +++ b/site.c @@ -551,7 +551,7 @@ static _Bool set_new_transform(struct site *st, char *pk) _Bool ok; /* Make room for the shared key */ - st->sharedsecretlen=st->chosen_transform->keylen?:st->dh->ceil_len; + st->sharedsecretlen=st->chosen_transform->keylen?:st->dh->shared_len; assert(st->sharedsecretlen); if (st->sharedsecretlen > st->sharedsecretallocd) { st->sharedsecretallocd=st->sharedsecretlen; @@ -561,8 +561,8 @@ static _Bool set_new_transform(struct site *st, char *pk) } /* Generate the shared key */ - if (!st->dh->makeshared(st->dh->st,st->dhsecret,st->dh->len,pk, - st->sharedsecret,st->sharedsecretlen)) + if (!st->dh->makeshared(st->dh->st,st->dhsecret,st->dh->secret_len, + pk, st->sharedsecret,st->sharedsecretlen)) return False; /* Set up the transform */ @@ -648,7 +648,7 @@ static bool_t generate_msg(struct site *st, uint32_t type, cstring_t what) if (type==LABEL_MSG3BIS) buf_append_uint8(&st->buffer,st->chosen_transform->capab_bit); - dhpub=st->dh->makepublic(st->dh->st,st->dhsecret,st->dh->len); + dhpub=st->dh->makepublic(st->dh->st,st->dhsecret,st->dh->secret_len); buf_append_string(&st->buffer,dhpub); free(dhpub); hash=safe_malloc(st->hash->len, "generate_msg"); @@ -862,7 +862,7 @@ static bool_t generate_msg3(struct site *st) { /* Now we have our nonce and their nonce. Think of a secret key, and create message number 3. */ - st->random->generate(st->random->st,st->dh->len,st->dhsecret); + st->random->generate(st->random->st,st->dh->secret_len,st->dhsecret); return generate_msg(st, (st->remote_capabilities & CAPAB_TRANSFORM_MASK ? LABEL_MSG3BIS : LABEL_MSG3), @@ -941,7 +941,7 @@ kind##_found: \ /* Terminate their DH public key with a '0' */ m.pk[m.pklen]=0; /* Invent our DH secret key */ - st->random->generate(st->random->st,st->dh->len,st->dhsecret); + st->random->generate(st->random->st,st->dh->secret_len,st->dhsecret); /* Generate the shared key and set up the transform */ if (!set_new_transform(st,m.pk)) return False; @@ -1502,7 +1502,7 @@ static void enter_state_run(struct site *st) FILLZERO(st->localN); FILLZERO(st->remoteN); dispose_transform(&st->new_transform); - memset(st->dhsecret,0,st->dh->len); + memset(st->dhsecret,0,st->dh->secret_len); if (st->sharedsecret) memset(st->sharedsecret,0,st->sharedsecretlen); set_link_quality(st); @@ -2241,7 +2241,7 @@ static list_t *site_apply(closure_t *self, struct cloc loc, dict_t *context, transport_peers_clear(st,&st->peers); transport_peers_clear(st,&st->setup_peers); /* XXX mlock these */ - st->dhsecret=safe_malloc(st->dh->len,"site:dhsecret"); + st->dhsecret=safe_malloc(st->dh->secret_len,"site:dhsecret"); st->sharedsecretlen=st->sharedsecretallocd=0; st->sharedsecret=0; -- 2.11.0