NULL_RETURNS paranoid check [CID-66]

[heimdal.git] / lib / krb5 / get_for_creds.c

/*
 * Copyright (c) 1997 - 2004 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <krb5_locl.h>

static krb5_error_code
add_addrs(krb5_context context,
          krb5_addresses *addr,
          struct addrinfo *ai)
{
    krb5_error_code ret;
    unsigned n, i;
    void *tmp;
    struct addrinfo *a;

    n = 0;
    for (a = ai; a != NULL; a = a->ai_next)
        ++n;

    tmp = realloc(addr->val, (addr->len + n) * sizeof(*addr->val));
    if (tmp == NULL && (addr->len + n) != 0) {
        ret = ENOMEM;
        krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
        goto fail;
    }
    addr->val = tmp;
    for (i = addr->len; i < (addr->len + n); ++i) {
        addr->val[i].addr_type = 0;
        krb5_data_zero(&addr->val[i].address);
    }
    i = addr->len;
    for (a = ai; a != NULL; a = a->ai_next) {
        krb5_address ad;

        ret = krb5_sockaddr2address (context, a->ai_addr, &ad);
        if (ret == 0) {
            if (krb5_address_search(context, &ad, addr))
                krb5_free_address(context, &ad);
            else
                addr->val[i++] = ad;
        }
        else if (ret == KRB5_PROG_ATYPE_NOSUPP)
            krb5_clear_error_message (context);
        else
            goto fail;
        addr->len = i;
    }
    return 0;
fail:
    krb5_free_addresses (context, addr);
    return ret;
}

/**
 * Forward credentials for client to host hostname , making them
 * forwardable if forwardable, and returning the blob of data to sent
 * in out_data.  If hostname == NULL, pick it from server.
 *
 * @param context A kerberos 5 context.
 * @param auth_context the auth context with the key to encrypt the out_data.
 * @param hostname the host to forward the tickets too.
 * @param client the client to delegate from.
 * @param server the server to delegate the credential too.
 * @param ccache credential cache to use.
 * @param forwardable make the forwarded ticket forwabledable.
 * @param out_data the resulting credential.
 *
 * @return Return an error code or 0.
 *
 * @ingroup krb5_credential
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_fwd_tgt_creds (krb5_context        context,
                    krb5_auth_context   auth_context,
                    const char          *hostname,
                    krb5_principal      client,
                    krb5_principal      server,
                    krb5_ccache         ccache,
                    int                 forwardable,
                    krb5_data           *out_data)
{
    krb5_flags flags = 0;
    krb5_creds creds;
    krb5_error_code ret;
    krb5_const_realm client_realm;

    flags |= KDC_OPT_FORWARDED;

    if (forwardable)
        flags |= KDC_OPT_FORWARDABLE;

    if (hostname == NULL &&
        krb5_principal_get_type(context, server) == KRB5_NT_SRV_HST) {
        const char *inst = krb5_principal_get_comp_string(context, server, 0);
        const char *host = krb5_principal_get_comp_string(context, server, 1);

        if (inst != NULL &&
            strcmp(inst, "host") == 0 &&
            host != NULL &&
            krb5_principal_get_comp_string(context, server, 2) == NULL)
            hostname = host;
    }

    client_realm = krb5_principal_get_realm(context, client);

    memset (&creds, 0, sizeof(creds));
    creds.client = client;

    ret = krb5_build_principal(context,
                               &creds.server,
                               strlen(client_realm),
                               client_realm,
                               KRB5_TGS_NAME,
                               client_realm,
                               NULL);
    if (ret)
        return ret;

    ret = krb5_get_forwarded_creds (context,
                                    auth_context,
                                    ccache,
                                    flags,
                                    hostname,
                                    &creds,
                                    out_data);
    return ret;
}

/**
 * Gets tickets forwarded to hostname. If the tickets that are
 * forwarded are address-less, the forwarded tickets will also be
 * address-less.
 *
 * If the ticket have any address, hostname will be used for figure
 * out the address to forward the ticket too. This since this might
 * use DNS, its insecure and also doesn't represent configured all
 * addresses of the host. For example, the host might have two
 * adresses, one IPv4 and one IPv6 address where the later is not
 * published in DNS. This IPv6 address might be used communications
 * and thus the resulting ticket useless.
 *
 * @param context A kerberos 5 context.
 * @param auth_context the auth context with the key to encrypt the out_data.
 * @param ccache credential cache to use
 * @param flags the flags to control the resulting ticket flags
 * @param hostname the host to forward the tickets too.
 * @param in_creds the in client and server ticket names.  The client
 * and server components forwarded to the remote host.
 * @param out_data the resulting credential.
 *
 * @return Return an error code or 0.
 *
 * @ingroup krb5_credential
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_get_forwarded_creds (krb5_context      context,
                          krb5_auth_context auth_context,
                          krb5_ccache       ccache,
                          krb5_flags        flags,
                          const char        *hostname,
                          krb5_creds        *in_creds,
                          krb5_data         *out_data)
{
    krb5_error_code ret;
    krb5_creds *out_creds;
    krb5_addresses addrs, *paddrs;
    KRB_CRED cred;
    KrbCredInfo *krb_cred_info;
    EncKrbCredPart enc_krb_cred_part;
    size_t len;
    unsigned char *buf;
    size_t buf_size;
    krb5_kdc_flags kdc_flags;
    krb5_crypto crypto;
    struct addrinfo *ai;
    krb5_creds *ticket;

    paddrs = NULL;
    addrs.len = 0;
    addrs.val = NULL;

    ret = krb5_get_credentials(context, 0, ccache, in_creds, &ticket);
    if(ret == 0) {
        if (ticket->addresses.len)
            paddrs = &addrs;
        krb5_free_creds (context, ticket);
    } else {
        krb5_boolean noaddr;
        krb5_appdefault_boolean(context, NULL,
                                krb5_principal_get_realm(context,
                                                         in_creds->client),
                                "no-addresses", KRB5_ADDRESSLESS_DEFAULT,
                                &noaddr);
        if (!noaddr)
            paddrs = &addrs;
    }
        
    /*
     * If tickets have addresses, get the address of the remote host.
     */

    if (paddrs != NULL) {

        ret = getaddrinfo (hostname, NULL, NULL, &ai);
        if (ret) {
            krb5_error_code ret2 = krb5_eai_to_heim_errno(ret, errno);
            krb5_set_error_message(context, ret2,
                                   N_("resolving host %s failed: %s",
                                      "hostname, error"),
                                  hostname, gai_strerror(ret));
            return ret2;
        }
        
        ret = add_addrs (context, &addrs, ai);
        freeaddrinfo (ai);
        if (ret)
            return ret;
    }

    kdc_flags.b = int2KDCOptions(flags);

    ret = krb5_get_kdc_cred (context,
                             ccache,
                             kdc_flags,
                             paddrs,
                             NULL,
                             in_creds,
                             &out_creds);
    krb5_free_addresses (context, &addrs);
    if (ret)
        return ret;

    memset (&cred, 0, sizeof(cred));
    cred.pvno = 5;
    cred.msg_type = krb_cred;
    ALLOC_SEQ(&cred.tickets, 1);
    if (cred.tickets.val == NULL) {
        ret = ENOMEM;
        krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
        goto out2;
    }
    ret = decode_Ticket(out_creds->ticket.data,
                        out_creds->ticket.length,
                        cred.tickets.val, &len);
    if (ret)
        goto out3;

    memset (&enc_krb_cred_part, 0, sizeof(enc_krb_cred_part));
    ALLOC_SEQ(&enc_krb_cred_part.ticket_info, 1);
    if (enc_krb_cred_part.ticket_info.val == NULL) {
        ret = ENOMEM;
        krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
        goto out4;
    }

    if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_TIME) {
        krb5_timestamp sec;
        int32_t usec;
        
        krb5_us_timeofday (context, &sec, &usec);
        
        ALLOC(enc_krb_cred_part.timestamp, 1);
        if (enc_krb_cred_part.timestamp == NULL) {
            ret = ENOMEM;
            krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
            goto out4;
        }
        *enc_krb_cred_part.timestamp = sec;
        ALLOC(enc_krb_cred_part.usec, 1);
        if (enc_krb_cred_part.usec == NULL) {
            ret = ENOMEM;
            krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
            goto out4;
        }
        *enc_krb_cred_part.usec      = usec;
    } else {
        enc_krb_cred_part.timestamp = NULL;
        enc_krb_cred_part.usec = NULL;
    }

    if (auth_context->local_address && auth_context->local_port && paddrs) {

        ret = krb5_make_addrport (context,
                                  &enc_krb_cred_part.s_address,
                                  auth_context->local_address,
                                  auth_context->local_port);
        if (ret)
            goto out4;
    }

    if (auth_context->remote_address) {
        if (auth_context->remote_port) {
            krb5_boolean noaddr;
            krb5_const_realm srealm;

            srealm = krb5_principal_get_realm(context, out_creds->server);
            /* Is this correct, and should we use the paddrs == NULL
               trick here as well? Having an address-less ticket may
               indicate that we don't know our own global address, but
               it does not necessary mean that we don't know the
               server's. */
            krb5_appdefault_boolean(context, NULL, srealm, "no-addresses",
                                    FALSE, &noaddr);
            if (!noaddr) {
                ret = krb5_make_addrport (context,
                                          &enc_krb_cred_part.r_address,
                                          auth_context->remote_address,
                                          auth_context->remote_port);
                if (ret)
                    goto out4;
            }
        } else {
            ALLOC(enc_krb_cred_part.r_address, 1);
            if (enc_krb_cred_part.r_address == NULL) {
                ret = ENOMEM;
                krb5_set_error_message(context, ret,
                                       N_("malloc: out of memory", ""));
                goto out4;
            }

            ret = krb5_copy_address (context, auth_context->remote_address,
                                     enc_krb_cred_part.r_address);
            if (ret)
                goto out4;
        }
    }

    /* fill ticket_info.val[0] */

    enc_krb_cred_part.ticket_info.len = 1;

    krb_cred_info = enc_krb_cred_part.ticket_info.val;

    copy_EncryptionKey (&out_creds->session, &krb_cred_info->key);
    ALLOC(krb_cred_info->prealm, 1);
    copy_Realm (&out_creds->client->realm, krb_cred_info->prealm);
    ALLOC(krb_cred_info->pname, 1);
    copy_PrincipalName(&out_creds->client->name, krb_cred_info->pname);
    ALLOC(krb_cred_info->flags, 1);
    *krb_cred_info->flags          = out_creds->flags.b;
    ALLOC(krb_cred_info->authtime, 1);
    *krb_cred_info->authtime       = out_creds->times.authtime;
    ALLOC(krb_cred_info->starttime, 1);
    *krb_cred_info->starttime      = out_creds->times.starttime;
    ALLOC(krb_cred_info->endtime, 1);
    *krb_cred_info->endtime        = out_creds->times.endtime;
    ALLOC(krb_cred_info->renew_till, 1);
    *krb_cred_info->renew_till = out_creds->times.renew_till;
    ALLOC(krb_cred_info->srealm, 1);
    copy_Realm (&out_creds->server->realm, krb_cred_info->srealm);
    ALLOC(krb_cred_info->sname, 1);
    copy_PrincipalName (&out_creds->server->name, krb_cred_info->sname);
    ALLOC(krb_cred_info->caddr, 1);
    copy_HostAddresses (&out_creds->addresses, krb_cred_info->caddr);

    krb5_free_creds (context, out_creds);

    /* encode EncKrbCredPart */

    ASN1_MALLOC_ENCODE(EncKrbCredPart, buf, buf_size,
                       &enc_krb_cred_part, &len, ret);
    free_EncKrbCredPart (&enc_krb_cred_part);
    if (ret) {
        free_KRB_CRED(&cred);
        return ret;
    }
    if(buf_size != len)
        krb5_abortx(context, "internal error in ASN.1 encoder");

    /**
     * Some older of the MIT gssapi library used clear-text tickets
     * (warped inside AP-REQ encryption), use the krb5_auth_context
     * flag KRB5_AUTH_CONTEXT_CLEAR_FORWARDED_CRED to support those
     * tickets. The session key is used otherwise to encrypt the
     * forwarded ticket.
     */

    if (auth_context->flags & KRB5_AUTH_CONTEXT_CLEAR_FORWARDED_CRED) {
        cred.enc_part.etype = ENCTYPE_NULL;
        cred.enc_part.kvno = NULL;
        cred.enc_part.cipher.data = buf;
        cred.enc_part.cipher.length = buf_size;
    } else {
        /*
         * Here older versions then 0.7.2 of Heimdal used the local or
         * remote subkey. That is wrong, the session key should be
         * used. Heimdal 0.7.2 and newer have code to try both in the
         * receiving end.
         */
        
        ret = krb5_crypto_init(context, auth_context->keyblock, 0, &crypto);
        if (ret) {
            free(buf);
            free_KRB_CRED(&cred);
            return ret;
        }
        ret = krb5_encrypt_EncryptedData (context,
                                          crypto,
                                          KRB5_KU_KRB_CRED,
                                          buf,
                                          len,
                                          0,
                                          &cred.enc_part);
        free(buf);
        krb5_crypto_destroy(context, crypto);
        if (ret) {
            free_KRB_CRED(&cred);
            return ret;
        }
    }

    ASN1_MALLOC_ENCODE(KRB_CRED, buf, buf_size, &cred, &len, ret);
    free_KRB_CRED (&cred);
    if (ret)
        return ret;
    if(buf_size != len)
        krb5_abortx(context, "internal error in ASN.1 encoder");
    out_data->length = len;
    out_data->data   = buf;
    return 0;
 out4:
    free_EncKrbCredPart(&enc_krb_cred_part);
 out3:
    free_KRB_CRED(&cred);
 out2:
    krb5_free_creds (context, out_creds);
    return ret;
}