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|
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 1999-2005, 2007-2008, 2010-2015
* Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Sponsored in part by the Defense Advanced Research Projects
* Agency (DARPA) and Air Force Research Laboratory, Air Force
* Materiel Command, USAF, under agreement number F39502-99-1-0512.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#ifdef HAVE_KERB5
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pwd.h>
#include <krb5.h>
#ifdef HAVE_HEIMDAL
#include <com_err.h>
#endif
#include "sudoers.h"
#include "sudo_auth.h"
#ifdef HAVE_HEIMDAL
# define extract_name(c, p) krb5_principal_get_comp_string(c, p, 1)
# define krb5_free_data_contents(c, d) krb5_data_free(d)
#else
# define extract_name(c, p) (krb5_princ_component(c, p, 1)->data)
#endif
#ifndef HAVE_KRB5_VERIFY_USER
static int verify_krb_v5_tgt(krb5_context, krb5_creds *, char *);
#endif
static struct _sudo_krb5_data {
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
} sudo_krb5_data = { NULL, NULL, NULL };
typedef struct _sudo_krb5_data *sudo_krb5_datap;
#ifdef SUDO_KRB5_INSTANCE
static const char *sudo_krb5_instance = SUDO_KRB5_INSTANCE;
#else
static const char *sudo_krb5_instance = NULL;
#endif
#ifndef HAVE_KRB5_GET_INIT_CREDS_OPT_ALLOC
static krb5_error_code
krb5_get_init_creds_opt_alloc(krb5_context context,
krb5_get_init_creds_opt **opts)
{
*opts = malloc(sizeof(krb5_get_init_creds_opt));
if (*opts == NULL)
return KRB5_CC_NOMEM;
krb5_get_init_creds_opt_init(*opts);
return 0;
}
static void
krb5_get_init_creds_opt_free(krb5_get_init_creds_opt *opts)
{
free(opts);
}
#endif
int
sudo_krb5_setup(struct passwd *pw, char **promptp, sudo_auth *auth)
{
static char *krb5_prompt;
debug_decl(sudo_krb5_init, SUDOERS_DEBUG_AUTH);
/* Don't override the prompt if the user specified their own. */
if (strcmp(*promptp, PASSPROMPT) != 0) {
debug_return_int(AUTH_SUCCESS);
}
if (krb5_prompt == NULL) {
krb5_context sudo_context;
krb5_principal princ;
char *pname;
krb5_error_code error;
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
/*
* Really, we need to tell the caller not to prompt for password. The
* API does not currently provide this unless the auth is standalone.
*/
if ((error = krb5_unparse_name(sudo_context, princ, &pname))) {
log_warningx(0,
N_("%s: unable to convert principal to string ('%s'): %s"),
auth->name, pw->pw_name, error_message(error));
debug_return_int(AUTH_FAILURE);
}
if (asprintf(&krb5_prompt, "Password for %s: ", pname) == -1) {
log_warningx(0, N_("unable to allocate memory"));
free(pname);
debug_return_int(AUTH_FATAL);
}
free(pname);
}
*promptp = krb5_prompt;
debug_return_int(AUTH_SUCCESS);
}
int
sudo_krb5_init(struct passwd *pw, sudo_auth *auth)
{
krb5_context sudo_context;
krb5_error_code error;
char cache_name[64], *pname = pw->pw_name;
debug_decl(sudo_krb5_init, SUDOERS_DEBUG_AUTH);
/* Only initialize once. */
if (auth->data != NULL)
debug_return_int(AUTH_SUCCESS);
if (sudo_krb5_instance != NULL) {
int len = asprintf(&pname, "%s%s%s", pw->pw_name,
sudo_krb5_instance[0] != '/' ? "/" : "", sudo_krb5_instance);
if (len == -1) {
log_warningx(0, N_("unable to allocate memory"));
debug_return_int(AUTH_FATAL);
}
}
#ifdef HAVE_KRB5_INIT_SECURE_CONTEXT
error = krb5_init_secure_context(&(sudo_krb5_data.sudo_context));
#else
error = krb5_init_context(&(sudo_krb5_data.sudo_context));
#endif
if (error)
goto done;
sudo_context = sudo_krb5_data.sudo_context;
error = krb5_parse_name(sudo_context, pname, &(sudo_krb5_data.princ));
if (error) {
log_warningx(0, N_("%s: unable to parse '%s': %s"), auth->name, pname,
error_message(error));
goto done;
}
(void) snprintf(cache_name, sizeof(cache_name), "MEMORY:sudocc_%ld",
(long) getpid());
if ((error = krb5_cc_resolve(sudo_context, cache_name,
&(sudo_krb5_data.ccache)))) {
log_warningx(0, N_("%s: unable to resolve credential cache: %s"),
auth->name, error_message(error));
goto done;
}
auth->data = (void *) &sudo_krb5_data; /* Stash all our data here */
done:
if (sudo_krb5_instance != NULL)
free(pname);
debug_return_int(error ? AUTH_FAILURE : AUTH_SUCCESS);
}
#ifdef HAVE_KRB5_VERIFY_USER
int
sudo_krb5_verify(struct passwd *pw, const char *pass, sudo_auth *auth, struct sudo_conv_callback *callback)
{
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
krb5_error_code error;
debug_decl(sudo_krb5_verify, SUDOERS_DEBUG_AUTH);
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
ccache = ((sudo_krb5_datap) auth->data)->ccache;
error = krb5_verify_user(sudo_context, princ, ccache, pass, 1, NULL);
debug_return_int(error ? AUTH_FAILURE : AUTH_SUCCESS);
}
#else
int
sudo_krb5_verify(struct passwd *pw, const char *pass, sudo_auth *auth, struct sudo_conv_callback *callback)
{
krb5_context sudo_context;
krb5_principal princ;
krb5_creds credbuf, *creds = NULL;
krb5_ccache ccache;
krb5_error_code error;
krb5_get_init_creds_opt *opts = NULL;
debug_decl(sudo_krb5_verify, SUDOERS_DEBUG_AUTH);
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
ccache = ((sudo_krb5_datap) auth->data)->ccache;
/* Set default flags based on the local config file. */
error = krb5_get_init_creds_opt_alloc(sudo_context, &opts);
if (error) {
log_warningx(0, N_("%s: unable to allocate options: %s"), auth->name,
error_message(error));
goto done;
}
#ifdef HAVE_HEIMDAL
krb5_get_init_creds_opt_set_default_flags(sudo_context, NULL,
krb5_principal_get_realm(sudo_context, princ), opts);
#endif
/* Note that we always obtain a new TGT to verify the user */
if ((error = krb5_get_init_creds_password(sudo_context, &credbuf, princ,
pass, krb5_prompter_posix,
NULL, 0, NULL, opts))) {
/* Don't print error if just a bad password */
if (error != KRB5KRB_AP_ERR_BAD_INTEGRITY) {
log_warningx(0, N_("%s: unable to get credentials: %s"),
auth->name, error_message(error));
}
goto done;
}
creds = &credbuf;
/* Verify the TGT to prevent spoof attacks. */
if ((error = verify_krb_v5_tgt(sudo_context, creds, auth->name)))
goto done;
/* Store credential in cache. */
if ((error = krb5_cc_initialize(sudo_context, ccache, princ))) {
log_warningx(0, N_("%s: unable to initialize credential cache: %s"),
auth->name, error_message(error));
} else if ((error = krb5_cc_store_cred(sudo_context, ccache, creds))) {
log_warningx(0, N_("%s: unable to store credential in cache: %s"),
auth->name, error_message(error));
}
done:
if (opts) {
#ifdef HAVE_KRB5_GET_INIT_CREDS_OPT_FREE_TWO_ARGS
krb5_get_init_creds_opt_free(sudo_context, opts);
#else
krb5_get_init_creds_opt_free(opts);
#endif
}
if (creds)
krb5_free_cred_contents(sudo_context, creds);
debug_return_int(error ? AUTH_FAILURE : AUTH_SUCCESS);
}
#endif
int
sudo_krb5_cleanup(struct passwd *pw, sudo_auth *auth, bool force)
{
krb5_context sudo_context;
krb5_principal princ;
krb5_ccache ccache;
debug_decl(sudo_krb5_cleanup, SUDOERS_DEBUG_AUTH);
sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context;
princ = ((sudo_krb5_datap) auth->data)->princ;
ccache = ((sudo_krb5_datap) auth->data)->ccache;
if (sudo_context) {
if (ccache)
krb5_cc_destroy(sudo_context, ccache);
if (princ)
krb5_free_principal(sudo_context, princ);
krb5_free_context(sudo_context);
}
debug_return_int(AUTH_SUCCESS);
}
#ifndef HAVE_KRB5_VERIFY_USER
/*
* Verify the Kerberos ticket-granting ticket just retrieved for the
* user. If the Kerberos server doesn't respond, assume the user is
* trying to fake us out (since we DID just get a TGT from what is
* supposedly our KDC).
*
* Returns 0 for successful authentication, non-zero for failure.
*/
static int
verify_krb_v5_tgt(krb5_context sudo_context, krb5_creds *cred, char *auth_name)
{
krb5_error_code error;
krb5_principal server;
krb5_verify_init_creds_opt vopt;
debug_decl(verify_krb_v5_tgt, SUDOERS_DEBUG_AUTH);
/*
* Get the server principal for the local host.
* (Use defaults of "host" and canonicalized local name.)
*/
if ((error = krb5_sname_to_principal(sudo_context, NULL, NULL,
KRB5_NT_SRV_HST, &server))) {
log_warningx(0, N_("%s: unable to get host principal: %s"), auth_name,
error_message(error));
debug_return_int(-1);
}
/* Initialize verify opts and set secure mode */
krb5_verify_init_creds_opt_init(&vopt);
krb5_verify_init_creds_opt_set_ap_req_nofail(&vopt, 1);
/* verify the Kerberos ticket-granting ticket we just retrieved */
error = krb5_verify_init_creds(sudo_context, cred, server, NULL,
NULL, &vopt);
krb5_free_principal(sudo_context, server);
if (error) {
log_warningx(0, N_("%s: Cannot verify TGT! Possible attack!: %s"),
auth_name, error_message(error));
}
debug_return_int(error);
}
#endif
#endif /* HAVE_KERB5 */
|
