369 lines
10 KiB
C
369 lines
10 KiB
C
/*
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* Copyright (c) 1999 Dug Song. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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RCSID("$OpenBSD: auth-krb4.c,v 1.29 2003/02/21 10:34:48 mpech Exp $");
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#include "ssh.h"
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#include "ssh1.h"
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#include "packet.h"
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#include "xmalloc.h"
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#include "log.h"
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#include "servconf.h"
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#include "uidswap.h"
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#include "auth.h"
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#ifdef AFS
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#include "radix.h"
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#endif
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#ifdef KRB4
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extern ServerOptions options;
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static int
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krb4_init(void *context)
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{
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static int cleanup_registered = 0;
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Authctxt *authctxt = (Authctxt *)context;
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const char *tkt_root = TKT_ROOT;
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struct stat st;
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int fd;
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if (!authctxt->krb4_ticket_file) {
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/* Set unique ticket string manually since we're still root. */
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authctxt->krb4_ticket_file = xmalloc(MAXPATHLEN);
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#ifdef AFS
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if (lstat("/ticket", &st) != -1)
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tkt_root = "/ticket/";
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#endif /* AFS */
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snprintf(authctxt->krb4_ticket_file, MAXPATHLEN, "%s%u_%ld",
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tkt_root, authctxt->pw->pw_uid, (long)getpid());
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krb_set_tkt_string(authctxt->krb4_ticket_file);
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}
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/* Register ticket cleanup in case of fatal error. */
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if (!cleanup_registered) {
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fatal_add_cleanup(krb4_cleanup_proc, authctxt);
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cleanup_registered = 1;
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}
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/* Try to create our ticket file. */
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if ((fd = mkstemp(authctxt->krb4_ticket_file)) != -1) {
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close(fd);
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return (1);
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}
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/* Ticket file exists - make sure user owns it (just passed ticket). */
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if (lstat(authctxt->krb4_ticket_file, &st) != -1) {
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if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
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st.st_uid == authctxt->pw->pw_uid)
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return (1);
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}
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/* Failure - cancel cleanup function, leaving ticket for inspection. */
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log("WARNING: bad ticket file %s", authctxt->krb4_ticket_file);
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fatal_remove_cleanup(krb4_cleanup_proc, authctxt);
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cleanup_registered = 0;
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xfree(authctxt->krb4_ticket_file);
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authctxt->krb4_ticket_file = NULL;
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return (0);
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}
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/*
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* try krb4 authentication,
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* return 1 on success, 0 on failure, -1 if krb4 is not available
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*/
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int
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auth_krb4_password(Authctxt *authctxt, const char *password)
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{
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AUTH_DAT adata;
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KTEXT_ST tkt;
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struct hostent *hp;
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struct passwd *pw;
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char localhost[MAXHOSTNAMELEN], phost[INST_SZ], realm[REALM_SZ];
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u_int32_t faddr;
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int r;
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if ((pw = authctxt->pw) == NULL)
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return (0);
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/*
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* Try Kerberos password authentication only for non-root
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* users and only if Kerberos is installed.
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*/
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if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
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/* Set up our ticket file. */
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if (!krb4_init(authctxt)) {
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log("Couldn't initialize Kerberos ticket file for %s!",
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pw->pw_name);
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goto failure;
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}
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/* Try to get TGT using our password. */
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r = krb_get_pw_in_tkt((char *) pw->pw_name, "", realm,
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"krbtgt", realm, DEFAULT_TKT_LIFE, (char *)password);
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if (r != INTK_OK) {
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debug("Kerberos v4 password authentication for %s "
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"failed: %s", pw->pw_name, krb_err_txt[r]);
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goto failure;
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}
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/* Successful authentication. */
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chown(tkt_string(), pw->pw_uid, pw->pw_gid);
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/*
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* Now that we have a TGT, try to get a local
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* "rcmd" ticket to ensure that we are not talking
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* to a bogus Kerberos server.
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*/
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gethostname(localhost, sizeof(localhost));
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strlcpy(phost, (char *)krb_get_phost(localhost),
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sizeof(phost));
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r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
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if (r == KSUCCESS) {
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if ((hp = gethostbyname(localhost)) == NULL) {
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log("Couldn't get local host address!");
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goto failure;
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}
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memmove((void *)&faddr, (void *)hp->h_addr,
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sizeof(faddr));
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/* Verify our "rcmd" ticket. */
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r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
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faddr, &adata, "");
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if (r == RD_AP_UNDEC) {
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/*
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* Probably didn't have a srvtab on
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* localhost. Disallow login.
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*/
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log("Kerberos v4 TGT for %s unverifiable, "
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"no srvtab installed? krb_rd_req: %s",
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pw->pw_name, krb_err_txt[r]);
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goto failure;
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} else if (r != KSUCCESS) {
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log("Kerberos v4 %s ticket unverifiable: %s",
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KRB4_SERVICE_NAME, krb_err_txt[r]);
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goto failure;
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}
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} else if (r == KDC_PR_UNKNOWN) {
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/*
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* Disallow login if no rcmd service exists, and
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* log the error.
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*/
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log("Kerberos v4 TGT for %s unverifiable: %s; %s.%s "
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"not registered, or srvtab is wrong?", pw->pw_name,
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krb_err_txt[r], KRB4_SERVICE_NAME, phost);
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goto failure;
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} else {
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/*
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* TGT is bad, forget it. Possibly spoofed!
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*/
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debug("WARNING: Kerberos v4 TGT possibly spoofed "
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"for %s: %s", pw->pw_name, krb_err_txt[r]);
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goto failure;
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}
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/* Authentication succeeded. */
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return (1);
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} else
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/* Logging in as root or no local Kerberos realm. */
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debug("Unable to authenticate to Kerberos.");
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failure:
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krb4_cleanup_proc(authctxt);
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if (!options.kerberos_or_local_passwd)
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return (0);
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/* Fall back to ordinary passwd authentication. */
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return (-1);
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}
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void
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krb4_cleanup_proc(void *context)
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{
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Authctxt *authctxt = (Authctxt *)context;
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debug("krb4_cleanup_proc called");
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if (authctxt->krb4_ticket_file) {
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(void) dest_tkt();
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xfree(authctxt->krb4_ticket_file);
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authctxt->krb4_ticket_file = NULL;
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}
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}
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int
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auth_krb4(Authctxt *authctxt, KTEXT auth, char **client, KTEXT reply)
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{
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AUTH_DAT adat = {0};
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Key_schedule schedule;
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struct sockaddr_in local, foreign;
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char instance[INST_SZ];
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socklen_t slen;
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u_int cksum;
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int r, s;
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s = packet_get_connection_in();
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slen = sizeof(local);
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memset(&local, 0, sizeof(local));
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if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
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debug("getsockname failed: %.100s", strerror(errno));
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slen = sizeof(foreign);
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memset(&foreign, 0, sizeof(foreign));
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if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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fatal_cleanup();
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}
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instance[0] = '*';
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instance[1] = 0;
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/* Get the encrypted request, challenge, and session key. */
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if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance,
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0, &adat, ""))) {
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debug("Kerberos v4 krb_rd_req: %.100s", krb_err_txt[r]);
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return (0);
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}
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des_key_sched((des_cblock *) adat.session, schedule);
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*client = xmalloc(MAX_K_NAME_SZ);
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(void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
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*adat.pinst ? "." : "", adat.pinst, adat.prealm);
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/* Check ~/.klogin authorization now. */
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if (kuserok(&adat, authctxt->user) != KSUCCESS) {
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log("Kerberos v4 .klogin authorization failed for %s to "
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"account %s", *client, authctxt->user);
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xfree(*client);
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*client = NULL;
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return (0);
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}
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/* Increment the checksum, and return it encrypted with the
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session key. */
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cksum = adat.checksum + 1;
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cksum = htonl(cksum);
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/* If we can't successfully encrypt the checksum, we send back an
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empty message, admitting our failure. */
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if ((r = krb_mk_priv((u_char *) & cksum, reply->dat, sizeof(cksum) + 1,
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schedule, &adat.session, &local, &foreign)) < 0) {
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debug("Kerberos v4 mk_priv: (%d) %s", r, krb_err_txt[r]);
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reply->dat[0] = 0;
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reply->length = 0;
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} else
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reply->length = r;
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/* Clear session key. */
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memset(&adat.session, 0, sizeof(adat.session));
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return (1);
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}
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#endif /* KRB4 */
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#ifdef AFS
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int
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auth_krb4_tgt(Authctxt *authctxt, const char *string)
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{
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CREDENTIALS creds;
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struct passwd *pw;
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if ((pw = authctxt->pw) == NULL)
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goto failure;
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temporarily_use_uid(pw);
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if (!radix_to_creds(string, &creds)) {
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log("Protocol error decoding Kerberos v4 TGT");
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goto failure;
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}
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if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
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strlcpy(creds.service, "krbtgt", sizeof creds.service);
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if (strcmp(creds.service, "krbtgt")) {
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log("Kerberos v4 TGT (%s%s%s@%s) rejected for %s",
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creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
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creds.realm, pw->pw_name);
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goto failure;
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}
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if (!krb4_init(authctxt))
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goto failure;
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if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
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goto failure;
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if (save_credentials(creds.service, creds.instance, creds.realm,
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creds.session, creds.lifetime, creds.kvno, &creds.ticket_st,
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creds.issue_date) != KSUCCESS) {
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debug("Kerberos v4 TGT refused: couldn't save credentials");
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goto failure;
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}
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/* Successful authentication, passed all checks. */
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chown(tkt_string(), pw->pw_uid, pw->pw_gid);
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debug("Kerberos v4 TGT accepted (%s%s%s@%s)",
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creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
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memset(&creds, 0, sizeof(creds));
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restore_uid();
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return (1);
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failure:
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krb4_cleanup_proc(authctxt);
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memset(&creds, 0, sizeof(creds));
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restore_uid();
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return (0);
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}
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int
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auth_afs_token(Authctxt *authctxt, const char *token_string)
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{
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CREDENTIALS creds;
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struct passwd *pw;
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uid_t uid;
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if ((pw = authctxt->pw) == NULL)
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return (0);
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if (!radix_to_creds(token_string, &creds)) {
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log("Protocol error decoding AFS token");
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return (0);
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}
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if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
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strlcpy(creds.service, "afs", sizeof creds.service);
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if (strncmp(creds.pname, "AFS ID ", 7) == 0)
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uid = atoi(creds.pname + 7);
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else
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uid = pw->pw_uid;
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if (kafs_settoken(creds.realm, uid, &creds)) {
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log("AFS token (%s@%s) rejected for %s",
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creds.pname, creds.realm, pw->pw_name);
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memset(&creds, 0, sizeof(creds));
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return (0);
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}
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debug("AFS token accepted (%s@%s)", creds.pname, creds.realm);
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memset(&creds, 0, sizeof(creds));
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return (1);
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}
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#endif /* AFS */
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