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Annotation of src/usr.bin/ssh/auth-rh-rsa.c, Revision 1.17

1.1       provos      1: /*
1.9       deraadt     2:  * Author: Tatu Ylonen <ylo@cs.hut.fi>
                      3:  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                      4:  *                    All rights reserved
                      5:  * Rhosts or /etc/hosts.equiv authentication combined with RSA host
                      6:  * authentication.
                      7:  *
1.15      deraadt     8:  * As far as I am concerned, the code I have written for this software
                      9:  * can be used freely for any purpose.  Any derived versions of this
                     10:  * software must be clearly marked as such, and if the derived work is
                     11:  * incompatible with the protocol description in the RFC file, it must be
                     12:  * called by a name other than "ssh" or "Secure Shell".
1.9       deraadt    13:  */
1.1       provos     14:
                     15: #include "includes.h"
1.17    ! markus     16: RCSID("$OpenBSD: auth-rh-rsa.c,v 1.16 2000/09/07 21:13:36 markus Exp $");
1.1       provos     17:
                     18: #include "packet.h"
                     19: #include "ssh.h"
                     20: #include "xmalloc.h"
                     21: #include "uidswap.h"
1.4       markus     22: #include "servconf.h"
1.1       provos     23:
1.12      markus     24: #include <openssl/rsa.h>
                     25: #include <openssl/dsa.h>
1.11      markus     26: #include "key.h"
                     27: #include "hostfile.h"
                     28:
1.10      markus     29: /*
                     30:  * Tries to authenticate the user using the .rhosts file and the host using
                     31:  * its host key.  Returns true if authentication succeeds.
                     32:  */
1.1       provos     33:
1.13      markus     34: int
1.11      markus     35: auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key)
1.1       provos     36: {
1.8       markus     37:        extern ServerOptions options;
                     38:        const char *canonical_hostname;
                     39:        HostStatus host_status;
1.11      markus     40:        Key *client_key, *found;
1.8       markus     41:
1.17    ! markus     42:        debug("Trying rhosts with RSA host authentication for client user %.100s", client_user);
1.8       markus     43:
1.17    ! markus     44:        if (pw == NULL || client_host_key == NULL)
1.11      markus     45:                return 0;
                     46:
1.8       markus     47:        /* Check if we would accept it using rhosts authentication. */
                     48:        if (!auth_rhosts(pw, client_user))
                     49:                return 0;
                     50:
                     51:        canonical_hostname = get_canonical_hostname();
                     52:
1.11      markus     53:        debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname);
                     54:
                     55:        /* wrap the RSA key into a 'generic' key */
                     56:        client_key = key_new(KEY_RSA);
                     57:        BN_copy(client_key->rsa->e, client_host_key->e);
                     58:        BN_copy(client_key->rsa->n, client_host_key->n);
                     59:        found = key_new(KEY_RSA);
1.8       markus     60:
                     61:        /* Check if we know the host and its host key. */
                     62:        host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
1.11      markus     63:            client_key, found);
1.8       markus     64:
                     65:        /* Check user host file unless ignored. */
                     66:        if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
                     67:                struct stat st;
                     68:                char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid);
1.10      markus     69:                /*
                     70:                 * Check file permissions of SSH_USER_HOSTFILE, auth_rsa()
                     71:                 * did already check pw->pw_dir, but there is a race XXX
                     72:                 */
1.8       markus     73:                if (options.strict_modes &&
                     74:                    (stat(user_hostfile, &st) == 0) &&
                     75:                    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
                     76:                     (st.st_mode & 022) != 0)) {
                     77:                        log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
                     78:                            pw->pw_name, user_hostfile);
                     79:                } else {
                     80:                        /* XXX race between stat and the following open() */
                     81:                        temporarily_use_uid(pw->pw_uid);
                     82:                        host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
1.11      markus     83:                            client_key, found);
1.8       markus     84:                        restore_uid();
                     85:                }
                     86:                xfree(user_hostfile);
                     87:        }
1.11      markus     88:        key_free(client_key);
                     89:        key_free(found);
1.8       markus     90:
                     91:        if (host_status != HOST_OK) {
                     92:                debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
                     93:                packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
                     94:                return 0;
                     95:        }
                     96:        /* A matching host key was found and is known. */
                     97:
                     98:        /* Perform the challenge-response dialog with the client for the host key. */
1.11      markus     99:        if (!auth_rsa_challenge_dialog(client_host_key)) {
1.8       markus    100:                log("Client on %.800s failed to respond correctly to host authentication.",
                    101:                    canonical_hostname);
                    102:                return 0;
                    103:        }
1.10      markus    104:        /*
                    105:         * We have authenticated the user using .rhosts or /etc/hosts.equiv,
                    106:         * and the host using RSA. We accept the authentication.
                    107:         */
1.8       markus    108:
                    109:        verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
1.11      markus    110:           pw->pw_name, client_user, canonical_hostname);
1.8       markus    111:        packet_send_debug("Rhosts with RSA host authentication accepted.");
                    112:        return 1;
1.1       provos    113: }