diff options
Diffstat (limited to 'agent/pksign.c')
| -rw-r--r-- | agent/pksign.c | 42 |
1 files changed, 39 insertions, 3 deletions
diff --git a/agent/pksign.c b/agent/pksign.c index 1d3d3d845..243c49df9 100644 --- a/agent/pksign.c +++ b/agent/pksign.c @@ -290,10 +290,12 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, const void *overridedata, size_t overridedatalen) { gcry_sexp_t s_skey = NULL, s_sig = NULL; + gcry_sexp_t s_hash = NULL; unsigned char *shadow_info = NULL; unsigned int rc = 0; /* FIXME: gpg-error? */ const unsigned char *data; int datalen; + int check_signature = 0; if (overridedata) { @@ -352,6 +354,7 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, if (is_RSA) { + check_signature = 1; if (*buf & 0x80) { len++; @@ -431,8 +434,7 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, else { /* No smartcard, but a private key */ - gcry_sexp_t s_hash = NULL; - int dsaalgo; + int dsaalgo = 0; /* Put the hash into a sexp */ if (agent_is_eddsa_key (s_skey)) @@ -454,6 +456,10 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, if (rc) goto leave; + if (dsaalgo == 0 && GCRYPT_VERSION_NUMBER < 0x010700) + /* It's RSA and Libgcrypt < 1.7 */ + check_signature = 1; + if (DBG_CRYPTO) { gcry_log_debugsxp ("skey", s_skey); @@ -462,7 +468,6 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, /* sign */ rc = gcry_pk_sign (&s_sig, s_hash, s_skey); - gcry_sexp_release (s_hash); if (rc) { log_error ("signing failed: %s\n", gpg_strerror (rc)); @@ -473,11 +478,42 @@ agent_pksign_do (ctrl_t ctrl, const char *cache_nonce, gcry_log_debugsxp ("rslt", s_sig); } + /* Check that the signature verification worked and nothing is + * fooling us e.g. by a bug in the signature create code or by + * deliberately introduced faults. Because Libgcrypt 1.7 does this + * for RSA internally there is no need to do it here again. */ + if (check_signature) + { + if (s_hash == NULL) + { + if (ctrl->digest.algo == MD_USER_TLS_MD5SHA1) + rc = do_encode_raw_pkcs1 (data, datalen, + gcry_pk_get_nbits (s_skey), + &s_hash); + else + rc = do_encode_md (data, datalen, + ctrl->digest.algo, + &s_hash, + ctrl->digest.raw_value); + } + + rc = gcry_pk_verify (s_sig, s_hash, s_skey); + + if (rc) + { + log_error (_("checking created signature failed: %s\n"), + gpg_strerror (rc)); + gcry_sexp_release (s_sig); + s_sig = NULL; + } + } + leave: *signature_sexp = s_sig; gcry_sexp_release (s_skey); + gcry_sexp_release (s_hash); xfree (shadow_info); return rc; |