s4-auth: Call krb5_get_init_creds_opt_set_canonicalize() in MIT case.

[Samba.git] / source4 / auth / kerberos / kerberos_util.c

/* 
   Unix SMB/CIFS implementation.

   Kerberos utility functions for GENSEC
   
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "system/kerberos.h"
#include "auth/kerberos/kerberos.h"
#include "auth/credentials/credentials.h"
#include "auth/credentials/credentials_proto.h"
#include "auth/credentials/credentials_krb5.h"
#include "auth/kerberos/kerberos_credentials.h"
#include "auth/kerberos/kerberos_util.h"

struct principal_container {
        struct smb_krb5_context *smb_krb5_context;
        krb5_principal principal;
        const char *string_form; /* Optional */
};

static krb5_error_code free_principal(struct principal_container *pc)
{
        /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
        krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);

        return 0;
}


static krb5_error_code parse_principal(TALLOC_CTX *parent_ctx,
                                       const char *princ_string,
                                       struct smb_krb5_context *smb_krb5_context,
                                       krb5_principal *princ,
                                       const char **error_string)
{
        int ret;
        struct principal_container *mem_ctx;
        if (princ_string == NULL) {
                 *princ = NULL;
                 return 0;
        }

        ret = krb5_parse_name(smb_krb5_context->krb5_context,
                              princ_string, princ);

        if (ret) {
                (*error_string) = smb_get_krb5_error_message(
                                                smb_krb5_context->krb5_context,
                                                ret, parent_ctx);
                return ret;
        }

        mem_ctx = talloc(parent_ctx, struct principal_container);
        if (!mem_ctx) {
                (*error_string) = error_message(ENOMEM);
                return ENOMEM;
        }

        /* This song-and-dance effectivly puts the principal
         * into talloc, so we can't loose it. */
        mem_ctx->smb_krb5_context = talloc_reference(mem_ctx,
                                                     smb_krb5_context);
        mem_ctx->principal = *princ;
        talloc_set_destructor(mem_ctx, free_principal);
        return 0;
}

/* Obtain the principal set on this context.  Requires a
 * smb_krb5_context because we are doing krb5 principal parsing with
 * the library routines.  The returned princ is placed in the talloc
 * system by means of a destructor (do *not* free). */

krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
                                struct cli_credentials *credentials,
                                struct smb_krb5_context *smb_krb5_context,
                                krb5_principal *princ,
                                enum credentials_obtained *obtained,
                                const char **error_string)
{
        krb5_error_code ret;
        const char *princ_string;
        TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
        *obtained = CRED_UNINITIALISED;

        if (!mem_ctx) {
                (*error_string) = error_message(ENOMEM);
                return ENOMEM;
        }
        princ_string = cli_credentials_get_principal_and_obtained(credentials,
                                                                  mem_ctx,
                                                                  obtained);
        if (!princ_string) {
                *princ = NULL;
                return 0;
        }

        ret = parse_principal(parent_ctx, princ_string,
                              smb_krb5_context, princ, error_string);
        talloc_free(mem_ctx);
        return ret;
}

/* Obtain the principal set on this context.  Requires a
 * smb_krb5_context because we are doing krb5 principal parsing with
 * the library routines.  The returned princ is placed in the talloc
 * system by means of a destructor (do *not* free). */

static krb5_error_code impersonate_principal_from_credentials(
                                TALLOC_CTX *parent_ctx,
                                struct cli_credentials *credentials,
                                struct smb_krb5_context *smb_krb5_context,
                                krb5_principal *princ,
                                const char **error_string)
{
        return parse_principal(parent_ctx,
                        cli_credentials_get_impersonate_principal(credentials),
                        smb_krb5_context, princ, error_string);
}

krb5_error_code smb_krb5_create_principals_array(TALLOC_CTX *mem_ctx,
                                                 krb5_context context,
                                                 const char *account_name,
                                                 const char *realm,
                                                 uint32_t num_spns,
                                                 const char *spns[],
                                                 uint32_t *pnum_principals,
                                                 krb5_principal **pprincipals,
                                                 const char **error_string)
{
        krb5_error_code code;
        TALLOC_CTX *tmp_ctx;
        uint32_t num_principals = 0;
        krb5_principal *principals;
        uint32_t i;

        tmp_ctx = talloc_new(mem_ctx);
        if (tmp_ctx == NULL) {
                *error_string = "Cannot allocate tmp_ctx";
                return ENOMEM;
        }

        if (realm == NULL) {
                *error_string = "Cannot create principal without a realm";
                code = EINVAL;
                goto done;
        }

        if (account_name == NULL && (num_spns == 0 || spns == NULL)) {
                *error_string = "Cannot create principal without an account or SPN";
                code = EINVAL;
                goto done;
        }

        if (account_name != NULL && account_name[0] != '\0') {
                num_principals++;
        }
        num_principals += num_spns;

        principals = talloc_zero_array(tmp_ctx,
                                       krb5_principal,
                                       num_principals);
        if (principals == NULL) {
                *error_string = "Cannot allocate principals";
                code = ENOMEM;
                goto done;
        }

        for (i = 0; i < num_spns; i++) {
                code = krb5_parse_name(context, spns[i], &(principals[i]));
                if (code != 0) {
                        *error_string = smb_get_krb5_error_message(context,
                                                                   code,
                                                                   mem_ctx);
                        goto done;
                }
        }

        if (account_name != NULL && account_name[0] != '\0') {
                code = smb_krb5_make_principal(context,
                                               &(principals[i]),
                                               realm,
                                               account_name,
                                               NULL);
                if (code != 0) {
                        *error_string = smb_get_krb5_error_message(context,
                                                                   code,
                                                                   mem_ctx);
                        goto done;
                }
        }

        if (pnum_principals != NULL) {
                *pnum_principals = num_principals;

                if (pprincipals != NULL) {
                        *pprincipals = talloc_steal(mem_ctx, principals);
                }
        }

        code = 0;
done:
        talloc_free(tmp_ctx);
        return code;
}

/**
 * Return a freshly allocated ccache (destroyed by destructor on child
 * of parent_ctx), for a given set of client credentials 
 */

 krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
                                 struct cli_credentials *credentials,
                                 struct smb_krb5_context *smb_krb5_context,
                                 struct tevent_context *event_ctx,
                                 krb5_ccache ccache,
                                 enum credentials_obtained *obtained,
                                 const char **error_string)
{
        krb5_error_code ret;
        const char *password;
        const char *self_service;
        const char *target_service;
        time_t kdc_time = 0;
        krb5_principal princ;
        krb5_principal impersonate_principal;
        int tries;
        TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
        krb5_get_init_creds_opt *krb_options;

        if (!mem_ctx) {
                (*error_string) = strerror(ENOMEM);
                return ENOMEM;
        }

        ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, obtained, error_string);
        if (ret) {
                talloc_free(mem_ctx);
                return ret;
        }

        if (princ == NULL) {
                (*error_string) = talloc_asprintf(credentials, "principal, username or realm was not specified in the credentials");
                talloc_free(mem_ctx);
                return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
        }

        ret = impersonate_principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &impersonate_principal, error_string);
        if (ret) {
                talloc_free(mem_ctx);
                return ret;
        }

        self_service = cli_credentials_get_self_service(credentials);
        target_service = cli_credentials_get_target_service(credentials);

        password = cli_credentials_get_password(credentials);

        /* setup the krb5 options we want */
        if ((ret = krb5_get_init_creds_opt_alloc(smb_krb5_context->krb5_context, &krb_options))) {
                (*error_string) = talloc_asprintf(credentials, "krb5_get_init_creds_opt_alloc failed (%s)\n",
                                                  smb_get_krb5_error_message(smb_krb5_context->krb5_context,
                                                                             ret, mem_ctx));
                talloc_free(mem_ctx);
                return ret;
        }

#ifdef SAMBA4_USES_HEIMDAL /* Disable for now MIT reads defaults when needed */
        /* get the defaults */
        krb5_get_init_creds_opt_set_default_flags(smb_krb5_context->krb5_context, NULL, NULL, krb_options);
#endif
        /* set if we want a forwardable ticket */
        switch (cli_credentials_get_krb_forwardable(credentials)) {
        case CRED_AUTO_KRB_FORWARDABLE:
                break;
        case CRED_NO_KRB_FORWARDABLE:
                krb5_get_init_creds_opt_set_forwardable(krb_options, FALSE);
                break;
        case CRED_FORCE_KRB_FORWARDABLE:
                krb5_get_init_creds_opt_set_forwardable(krb_options, TRUE);
                break;
        }

#ifdef SAMBA4_USES_HEIMDAL /* FIXME: MIT does not have this yet */
        /*
         * In order to work against windows KDCs even if we use
         * the netbios domain name as realm, we need to add the following
         * flags:
         * KRB5_INIT_CREDS_NO_C_CANON_CHECK;
         * KRB5_INIT_CREDS_NO_C_NO_EKU_CHECK;
         *
         * On MIT: Set pkinit_eku_checking to none
         */
        krb5_get_init_creds_opt_set_win2k(smb_krb5_context->krb5_context,
                                          krb_options, true);
#else /* MIT */
        krb5_get_init_creds_opt_set_canonicalize(krb_options, true);
#endif

        tries = 2;
        while (tries--) {
#ifdef SAMBA4_USES_HEIMDAL
                struct tevent_context *previous_ev;
                /* Do this every time, in case we have weird recursive issues here */
                ret = smb_krb5_context_set_event_ctx(smb_krb5_context, event_ctx, &previous_ev);
                if (ret) {
                        talloc_free(mem_ctx);
                        return ret;
                }
#endif
                if (password) {
                        if (impersonate_principal) {
#ifdef SAMBA4_USES_HEIMDAL
                                ret = kerberos_kinit_s4u2_cc(
                                                smb_krb5_context->krb5_context,
                                                ccache, princ, password,
                                                impersonate_principal,
                                                self_service, target_service,
                                                krb_options, NULL, &kdc_time);
#else
                                talloc_free(mem_ctx);
                                (*error_string) = "INTERNAL error: s4u2 ops "
                                        "are not supported with MIT build yet";
                                return EINVAL;
#endif
                        } else {
                                ret = kerberos_kinit_password_cc(
                                                smb_krb5_context->krb5_context,
                                                ccache, princ, password,
                                                target_service,
                                                krb_options, NULL, &kdc_time);
                        }
                } else if (impersonate_principal) {
                        talloc_free(mem_ctx);
                        (*error_string) = "INTERNAL error: Cannot impersonate principal with just a keyblock.  A password must be specified in the credentials";
                        return EINVAL;
                } else {
                        /* No password available, try to use a keyblock instead */
                        
                        krb5_keyblock keyblock;
                        const struct samr_Password *mach_pwd;
                        mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
                        if (!mach_pwd) {
                                talloc_free(mem_ctx);
                                (*error_string) = "kinit_to_ccache: No password available for kinit\n";
                                krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
#ifdef SAMBA4_USES_HEIMDAL
                                smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
#endif
                                return EINVAL;
                        }
                        ret = smb_krb5_keyblock_init_contents(smb_krb5_context->krb5_context,
                                                 ENCTYPE_ARCFOUR_HMAC,
                                                 mach_pwd->hash, sizeof(mach_pwd->hash), 
                                                 &keyblock);
                        
                        if (ret == 0) {
                                ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache, 
                                                                 princ, &keyblock,
                                                                 target_service, krb_options,
                                                                 NULL, &kdc_time);
                                krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
                        }
                }

#ifdef SAMBA4_USES_HEIMDAL
                smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
#endif

                if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
                        /* Perhaps we have been given an invalid skew, so try again without it */
                        time_t t = time(NULL);
                        krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
                } else {
                        /* not a skew problem */
                        break;
                }
        }

        krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);

        if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
                (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
                                                  cli_credentials_get_principal(credentials, mem_ctx),
                                                  smb_get_krb5_error_message(smb_krb5_context->krb5_context,
                                                                             ret, mem_ctx));
                talloc_free(mem_ctx);
                return ret;
        }

        /* cope with ticket being in the future due to clock skew */
        if ((unsigned)kdc_time > time(NULL)) {
                time_t t = time(NULL);
                int time_offset =(unsigned)kdc_time-t;
                DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
                krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
        }
        
        if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
                ret = kinit_to_ccache(parent_ctx,
                                      credentials,
                                      smb_krb5_context,
                                      event_ctx,
                                      ccache, obtained,
                                      error_string);
        }

        if (ret) {
                (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
                                                  cli_credentials_get_principal(credentials, mem_ctx),
                                                  smb_get_krb5_error_message(smb_krb5_context->krb5_context,
                                                                             ret, mem_ctx));
                talloc_free(mem_ctx);
                return ret;
        }

        DEBUG(10,("kinit for %s succeeded\n",
                cli_credentials_get_principal(credentials, mem_ctx)));


        talloc_free(mem_ctx);
        return 0;
}

static krb5_error_code free_keytab_container(struct keytab_container *ktc)
{
        return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
}

krb5_error_code smb_krb5_get_keytab_container(TALLOC_CTX *mem_ctx,
                                struct smb_krb5_context *smb_krb5_context,
                                krb5_keytab opt_keytab,
                                const char *keytab_name,
                                struct keytab_container **ktc)
{
        krb5_keytab keytab;
        krb5_error_code ret;

        if (opt_keytab) {
                keytab = opt_keytab;
        } else {
                ret = krb5_kt_resolve(smb_krb5_context->krb5_context,
                                                keytab_name, &keytab);
                if (ret) {
                        DEBUG(1,("failed to open krb5 keytab: %s\n",
                                 smb_get_krb5_error_message(
                                        smb_krb5_context->krb5_context,
                                        ret, mem_ctx)));
                        return ret;
                }
        }

        *ktc = talloc(mem_ctx, struct keytab_container);
        if (!*ktc) {
                return ENOMEM;
        }

        (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
        (*ktc)->keytab = keytab;
        (*ktc)->password_based = false;
        talloc_set_destructor(*ktc, free_keytab_container);

        return 0;
}

/*
 * Walk the keytab, looking for entries of this principal name,
 * with KVNO other than current kvno -1.
 *
 * These entries are now stale,
 * we only keep the current and previous entries around.
 *
 * Inspired by the code in Samba3 for 'use kerberos keytab'.
 */
krb5_error_code smb_krb5_remove_obsolete_keytab_entries(TALLOC_CTX *mem_ctx,
                                                        krb5_context context,
                                                        krb5_keytab keytab,
                                                        uint32_t num_principals,
                                                        krb5_principal *principals,
                                                        krb5_kvno kvno,
                                                        bool *found_previous,
                                                        const char **error_string)
{
        TALLOC_CTX *tmp_ctx;
        krb5_error_code code;
        krb5_kt_cursor cursor;

        tmp_ctx = talloc_new(mem_ctx);
        if (tmp_ctx == NULL) {
                *error_string = "Cannot allocate tmp_ctx";
                return ENOMEM;
        }

        *found_previous = true;

        code = krb5_kt_start_seq_get(context, keytab, &cursor);
        switch (code) {
        case 0:
                break;
#ifdef HEIM_ERR_OPNOTSUPP
        case HEIM_ERR_OPNOTSUPP:
#endif
        case ENOENT:
        case KRB5_KT_END:
                /* no point enumerating if there isn't anything here */
                code = 0;
                goto done;
        default:
                *error_string = talloc_asprintf(mem_ctx,
                                                "failed to open keytab for read of old entries: %s\n",
                                                smb_get_krb5_error_message(context, code, mem_ctx));
                goto done;
        }

        do {
                krb5_kvno old_kvno = kvno - 1;
                krb5_keytab_entry entry;
                bool matched = false;
                uint32_t i;

                code = krb5_kt_next_entry(context, keytab, &entry, &cursor);
                if (code) {
                        break;
                }

                for (i = 0; i < num_principals; i++) {
                        krb5_boolean ok;

                        ok = smb_krb5_kt_compare(context,
                                                &entry,
                                                principals[i],
                                                0,
                                                0);
                        if (ok) {
                                matched = true;
                                break;
                        }
                }

                if (!matched) {
                        /*
                         * Free the entry, it wasn't the one we were looking
                         * for anyway
                         */
                        krb5_kt_free_entry(context, &entry);
                        /* Make sure we do not double free */
                        ZERO_STRUCT(entry);
                        continue;
                }

                /*
                 * Delete it, if it is not kvno - 1.
                 *
                 * Some keytab files store the kvno only in 8bits. Limit the
                 * compare to 8bits, so that we don't miss old keys and delete
                 * them.
                 */
                if ((entry.vno & 0xff) != (old_kvno & 0xff)) {
                        krb5_error_code rc;

                        /* Release the enumeration.  We are going to
                         * have to start this from the top again,
                         * because deletes during enumeration may not
                         * always be consistent.
                         *
                         * Also, the enumeration locks a FILE: keytab
                         */
                        krb5_kt_end_seq_get(context, keytab, &cursor);

                        code = krb5_kt_remove_entry(context, keytab, &entry);
                        krb5_kt_free_entry(context, &entry);

                        /* Make sure we do not double free */
                        ZERO_STRUCT(entry);

                        /* Deleted: Restart from the top */
                        rc = krb5_kt_start_seq_get(context, keytab, &cursor);
                        if (rc != 0) {
                                krb5_kt_free_entry(context, &entry);

                                /* Make sure we do not double free */
                                ZERO_STRUCT(entry);

                                DEBUG(1, ("failed to restart enumeration of keytab: %s\n",
                                          smb_get_krb5_error_message(context,
                                                                     code,
                                                                     tmp_ctx)));

                                talloc_free(tmp_ctx);
                                return rc;
                        }

                        if (code != 0) {
                                break;
                        }

                } else {
                        *found_previous = true;
                }

                /* Free the entry, we don't need it any more */
                krb5_kt_free_entry(context, &entry);
                /* Make sure we do not double free */
                ZERO_STRUCT(entry);
        } while (code != 0);

        krb5_kt_end_seq_get(context, keytab, &cursor);

        switch (code) {
        case 0:
                break;
        case ENOENT:
        case KRB5_KT_END:
                code = 0;
                break;
        default:
                *error_string = talloc_asprintf(mem_ctx,
                                                "failed in deleting old entries for principal: %s\n",
                                                smb_get_krb5_error_message(context,
                                                                           code,
                                                                           mem_ctx));
        }

        code = 0;
done:
        talloc_free(tmp_ctx);
        return code;
}