From 67fa09f5ac2e9e0facd492800cb2b5676d4ed2f7 Mon Sep 17 00:00:00 2001 From: djm Date: Tue, 5 Feb 2002 01:26:03 +0000 Subject: [PATCH] - markus@cvs.openbsd.org 2002/02/04 11:58:10 [auth2.c] cross checking of announced vs actual pktype in pubkey/hostbaed auth; ok stevesk@ --- ChangeLog | 4 ++ auth2.c | 143 +++++++++++++++++++++++++++++------------------------- 2 files changed, 82 insertions(+), 65 deletions(-) diff --git a/ChangeLog b/ChangeLog index 8a0145e8..d6c15316 100644 --- a/ChangeLog +++ b/ChangeLog @@ -81,6 +81,10 @@ - stevesk@cvs.openbsd.org 2002/02/04 00:53:39 [ssh-agent.c] unneeded includes + - markus@cvs.openbsd.org 2002/02/04 11:58:10 + [auth2.c] + cross checking of announced vs actual pktype in pubkey/hostbaed auth; + ok stevesk@ 20020130 - (djm) Delay PRNG seeding until we need it in ssh-keygen, from markus@ diff --git a/auth2.c b/auth2.c index 6d91dea7..08f71918 100644 --- a/auth2.c +++ b/auth2.c @@ -23,7 +23,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth2.c,v 1.83 2002/01/29 14:32:03 markus Exp $"); +RCSID("$OpenBSD: auth2.c,v 1.84 2002/02/04 11:58:10 markus Exp $"); #include @@ -397,7 +397,7 @@ static int userauth_pubkey(Authctxt *authctxt) { Buffer b; - Key *key; + Key *key = NULL; char *pkalg, *pkblob, *sig; u_int alen, blen, slen; int have_sig, pktype; @@ -424,72 +424,80 @@ userauth_pubkey(Authctxt *authctxt) pktype = key_type_from_name(pkalg); if (pktype == KEY_UNSPEC) { /* this is perfectly legal */ - log("userauth_pubkey: unsupported public key algorithm: %s", pkalg); - xfree(pkalg); - xfree(pkblob); - return 0; + log("userauth_pubkey: unsupported public key algorithm: %s", + pkalg); + goto done; } key = key_from_blob(pkblob, blen); - if (key != NULL) { - if (have_sig) { - sig = packet_get_string(&slen); - packet_check_eom(); - buffer_init(&b); - if (datafellows & SSH_OLD_SESSIONID) { - buffer_append(&b, session_id2, session_id2_len); - } else { - buffer_put_string(&b, session_id2, session_id2_len); - } - /* reconstruct packet */ - buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); - buffer_put_cstring(&b, authctxt->user); - buffer_put_cstring(&b, - datafellows & SSH_BUG_PKSERVICE ? - "ssh-userauth" : - authctxt->service); - if (datafellows & SSH_BUG_PKAUTH) { - buffer_put_char(&b, have_sig); - } else { - buffer_put_cstring(&b, "publickey"); - buffer_put_char(&b, have_sig); - buffer_put_cstring(&b, pkalg); - } - buffer_put_string(&b, pkblob, blen); + if (key == NULL) { + error("userauth_pubkey: cannot decode key: %s", pkalg); + goto done; + } + if (key->type != pktype) { + error("userauth_pubkey: type mismatch for decoded key " + "(received %d, expected %d)", key->type, pktype); + goto done; + } + if (have_sig) { + sig = packet_get_string(&slen); + packet_check_eom(); + buffer_init(&b); + if (datafellows & SSH_OLD_SESSIONID) { + buffer_append(&b, session_id2, session_id2_len); + } else { + buffer_put_string(&b, session_id2, session_id2_len); + } + /* reconstruct packet */ + buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); + buffer_put_cstring(&b, authctxt->user); + buffer_put_cstring(&b, + datafellows & SSH_BUG_PKSERVICE ? + "ssh-userauth" : + authctxt->service); + if (datafellows & SSH_BUG_PKAUTH) { + buffer_put_char(&b, have_sig); + } else { + buffer_put_cstring(&b, "publickey"); + buffer_put_char(&b, have_sig); + buffer_put_cstring(&b, pkalg); + } + buffer_put_string(&b, pkblob, blen); #ifdef DEBUG_PK - buffer_dump(&b); + buffer_dump(&b); #endif - /* test for correct signature */ - if (user_key_allowed(authctxt->pw, key) && - key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) - authenticated = 1; - buffer_clear(&b); - xfree(sig); - } else { - debug("test whether pkalg/pkblob are acceptable"); - packet_check_eom(); - - /* XXX fake reply and always send PK_OK ? */ - /* - * XXX this allows testing whether a user is allowed - * to login: if you happen to have a valid pubkey this - * message is sent. the message is NEVER sent at all - * if a user is not allowed to login. is this an - * issue? -markus - */ - if (user_key_allowed(authctxt->pw, key)) { - packet_start(SSH2_MSG_USERAUTH_PK_OK); - packet_put_string(pkalg, alen); - packet_put_string(pkblob, blen); - packet_send(); - packet_write_wait(); - authctxt->postponed = 1; - } + /* test for correct signature */ + if (user_key_allowed(authctxt->pw, key) && + key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) + authenticated = 1; + buffer_clear(&b); + xfree(sig); + } else { + debug("test whether pkalg/pkblob are acceptable"); + packet_check_eom(); + + /* XXX fake reply and always send PK_OK ? */ + /* + * XXX this allows testing whether a user is allowed + * to login: if you happen to have a valid pubkey this + * message is sent. the message is NEVER sent at all + * if a user is not allowed to login. is this an + * issue? -markus + */ + if (user_key_allowed(authctxt->pw, key)) { + packet_start(SSH2_MSG_USERAUTH_PK_OK); + packet_put_string(pkalg, alen); + packet_put_string(pkblob, blen); + packet_send(); + packet_write_wait(); + authctxt->postponed = 1; } - if (authenticated != 1) - auth_clear_options(); - key_free(key); } + if (authenticated != 1) + auth_clear_options(); +done: debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); + if (key != NULL) + key_free(key); xfree(pkalg); xfree(pkblob); #ifdef HAVE_CYGWIN @@ -503,7 +511,7 @@ static int userauth_hostbased(Authctxt *authctxt) { Buffer b; - Key *key; + Key *key = NULL; char *pkalg, *pkblob, *sig, *cuser, *chost, *service; u_int alen, blen, slen; int pktype; @@ -537,7 +545,12 @@ userauth_hostbased(Authctxt *authctxt) } key = key_from_blob(pkblob, blen); if (key == NULL) { - debug("userauth_hostbased: cannot decode key: %s", pkalg); + error("userauth_hostbased: cannot decode key: %s", pkalg); + goto done; + } + if (key->type != pktype) { + error("userauth_hostbased: type mismatch for decoded key " + "(received %d, expected %d)", key->type, pktype); goto done; } service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : @@ -562,10 +575,10 @@ userauth_hostbased(Authctxt *authctxt) authenticated = 1; buffer_clear(&b); - key_free(key); - done: debug2("userauth_hostbased: authenticated %d", authenticated); + if (key != NULL) + key_free(key); xfree(pkalg); xfree(pkblob); xfree(cuser); -- 2.45.2