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Annotation of src/usr.bin/ssh/auth-rh-rsa.c, Revision 1.6

1.1       provos      1: /*
                      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: */
                     16:
                     17: #include "includes.h"
1.6     ! markus     18: RCSID("$Id: auth-rh-rsa.c,v 1.5 1999/11/11 23:36:52 markus 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:
                     26: /* Tries to authenticate the user using the .rhosts file and the host using
1.4       markus     27:    its host key.  Returns true if authentication succeeds. */
1.1       provos     28:
                     29: int auth_rhosts_rsa(struct passwd *pw, const char *client_user,
1.4       markus     30:                    BIGNUM *client_host_key_e, BIGNUM *client_host_key_n)
1.1       provos     31: {
1.4       markus     32:   extern ServerOptions options;
1.1       provos     33:   const char *canonical_hostname;
1.2       provos     34:   HostStatus host_status;
                     35:   BIGNUM *ke, *kn;
1.1       provos     36:
                     37:   debug("Trying rhosts with RSA host authentication for %.100s", client_user);
                     38:
                     39:   /* Check if we would accept it using rhosts authentication. */
1.5       markus     40:   if (!auth_rhosts(pw, client_user))
1.1       provos     41:     return 0;
                     42:
                     43:   canonical_hostname = get_canonical_hostname();
                     44:
                     45:   debug("Rhosts RSA authentication: canonical host %.900s",
                     46:        canonical_hostname);
                     47:
                     48:   /* Check if we know the host and its host key. */
                     49:   /* Check system-wide host file. */
1.2       provos     50:   ke = BN_new();
                     51:   kn = BN_new();
                     52:   host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
1.6     ! markus     53:                                       client_host_key_e, client_host_key_n, ke, kn);
1.4       markus     54:
                     55:   /* Check user host file unless ignored. */
                     56:   if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
1.3       markus     57:     struct stat st;
                     58:     char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid);
                     59:     /* Check file permissions of SSH_USER_HOSTFILE,
                     60:        auth_rsa() did already check pw->pw_dir, but there is a race XXX */
1.4       markus     61:     if (options.strict_modes &&
1.3       markus     62:        (stat(user_hostfile, &st) == 0) &&
                     63:        ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
                     64:        (st.st_mode & 022) != 0)) {
                     65:        log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
                     66:           pw->pw_name, user_hostfile);
                     67:     } else {
                     68:       /* XXX race between stat and the following open() */
                     69:       temporarily_use_uid(pw->pw_uid);
                     70:       host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
1.6     ! markus     71:                                           client_host_key_e, client_host_key_n, ke, kn);
1.3       markus     72:       restore_uid();
                     73:     }
                     74:     xfree(user_hostfile);
                     75:   }
1.2       provos     76:   BN_free(ke);
                     77:   BN_free(kn);
1.3       markus     78:
1.2       provos     79:   if (host_status != HOST_OK) {
                     80:     /* The host key was not found. */
                     81:     debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
                     82:     packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
                     83:     return 0;
                     84:   }
                     85:
1.1       provos     86:   /* A matching host key was found and is known. */
                     87:
                     88:   /* Perform the challenge-response dialog with the client for the host key. */
1.6     ! markus     89:   if (!auth_rsa_challenge_dialog(client_host_key_e, client_host_key_n))
1.1       provos     90:     {
                     91:       log("Client on %.800s failed to respond correctly to host authentication.",
                     92:          canonical_hostname);
                     93:       return 0;
                     94:     }
                     95:
                     96:   /* We have authenticated the user using .rhosts or /etc/hosts.equiv, and
                     97:      the host using RSA.  We accept the authentication. */
                     98:
                     99:   log("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
                    100:       pw->pw_name, client_user, canonical_hostname);
                    101:   packet_send_debug("Rhosts with RSA host authentication accepted.");
                    102:   return 1;
                    103: }