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Annotation of src/usr.bin/ssh/auth-rh-rsa.c, Revision 1.10

1.1       provos      1: /*
1.9       deraadt     2:  *
                      3:  * auth-rh-rsa.c
                      4:  *
                      5:  * Author: Tatu Ylonen <ylo@cs.hut.fi>
                      6:  *
                      7:  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                      8:  *                    All rights reserved
                      9:  *
                     10:  * Created: Sun May  7 03:08:06 1995 ylo
                     11:  *
                     12:  * Rhosts or /etc/hosts.equiv authentication combined with RSA host
                     13:  * authentication.
                     14:  *
                     15:  */
1.1       provos     16:
                     17: #include "includes.h"
1.10    ! markus     18: RCSID("$Id: auth-rh-rsa.c,v 1.9 1999/11/24 00:26:00 deraadt Exp $");
1.1       provos     19:
                     20: #include "packet.h"
                     21: #include "ssh.h"
                     22: #include "xmalloc.h"
                     23: #include "uidswap.h"
1.4       markus     24: #include "servconf.h"
1.1       provos     25:
1.10    ! markus     26: /*
        !            27:  * Tries to authenticate the user using the .rhosts file and the host using
        !            28:  * its host key.  Returns true if authentication succeeds.
        !            29:  */
1.1       provos     30:
1.8       markus     31: int
                     32: auth_rhosts_rsa(struct passwd *pw, const char *client_user,
                     33:                BIGNUM *client_host_key_e, BIGNUM *client_host_key_n)
1.1       provos     34: {
1.8       markus     35:        extern ServerOptions options;
                     36:        const char *canonical_hostname;
                     37:        HostStatus host_status;
                     38:        BIGNUM *ke, *kn;
                     39:
                     40:        debug("Trying rhosts with RSA host authentication for %.100s", client_user);
                     41:
                     42:        /* Check if we would accept it using rhosts authentication. */
                     43:        if (!auth_rhosts(pw, client_user))
                     44:                return 0;
                     45:
                     46:        canonical_hostname = get_canonical_hostname();
                     47:
                     48:        debug("Rhosts RSA authentication: canonical host %.900s",
                     49:              canonical_hostname);
                     50:
                     51:        /* Check if we know the host and its host key. */
                     52:        ke = BN_new();
                     53:        kn = BN_new();
                     54:        host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
                     55:                                             client_host_key_e, client_host_key_n,
                     56:                                             ke, kn);
                     57:
                     58:        /* Check user host file unless ignored. */
                     59:        if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
                     60:                struct stat st;
                     61:                char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid);
1.10    ! markus     62:                /*
        !            63:                 * Check file permissions of SSH_USER_HOSTFILE, auth_rsa()
        !            64:                 * did already check pw->pw_dir, but there is a race XXX
        !            65:                 */
1.8       markus     66:                if (options.strict_modes &&
                     67:                    (stat(user_hostfile, &st) == 0) &&
                     68:                    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
                     69:                     (st.st_mode & 022) != 0)) {
                     70:                        log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
                     71:                            pw->pw_name, user_hostfile);
                     72:                } else {
                     73:                        /* XXX race between stat and the following open() */
                     74:                        temporarily_use_uid(pw->pw_uid);
                     75:                        host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
                     76:                                                             client_host_key_e, client_host_key_n,
                     77:                                                             ke, kn);
                     78:                        restore_uid();
                     79:                }
                     80:                xfree(user_hostfile);
                     81:        }
                     82:        BN_free(ke);
                     83:        BN_free(kn);
                     84:
                     85:        if (host_status != HOST_OK) {
                     86:                debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
                     87:                packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
                     88:                return 0;
                     89:        }
                     90:        /* A matching host key was found and is known. */
                     91:
                     92:        /* Perform the challenge-response dialog with the client for the host key. */
                     93:        if (!auth_rsa_challenge_dialog(client_host_key_e, client_host_key_n)) {
                     94:                log("Client on %.800s failed to respond correctly to host authentication.",
                     95:                    canonical_hostname);
                     96:                return 0;
                     97:        }
1.10    ! markus     98:        /*
        !            99:         * We have authenticated the user using .rhosts or /etc/hosts.equiv,
        !           100:         * and the host using RSA. We accept the authentication.
        !           101:         */
1.8       markus    102:
                    103:        verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
                    104:                pw->pw_name, client_user, canonical_hostname);
                    105:        packet_send_debug("Rhosts with RSA host authentication accepted.");
                    106:        return 1;
1.1       provos    107: }