diff options
Diffstat (limited to 'source4/auth/kerberos/kerberos_verify.c')
| -rw-r--r-- | source4/auth/kerberos/kerberos_verify.c | 486 |
1 files changed, 486 insertions, 0 deletions
diff --git a/source4/auth/kerberos/kerberos_verify.c b/source4/auth/kerberos/kerberos_verify.c new file mode 100644 index 0000000000..3188e603cd --- /dev/null +++ b/source4/auth/kerberos/kerberos_verify.c @@ -0,0 +1,486 @@ +/* + Unix SMB/CIFS implementation. + kerberos utility library + Copyright (C) Andrew Tridgell 2001 + Copyright (C) Remus Koos 2001 + Copyright (C) Luke Howard 2003 + Copyright (C) Guenther Deschner 2003 + Copyright (C) Jim McDonough (jmcd@us.ibm.com) 2003 + 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 2 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, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +#include "includes.h" +#include "system/kerberos.h" +#include "auth/kerberos/kerberos.h" +#include "asn_1.h" +#include "lib/ldb/include/ldb.h" +#include "secrets.h" +#include "pstring.h" + +#ifdef HAVE_KRB5 + +#if !defined(HAVE_KRB5_PRINC_COMPONENT) +const krb5_data *krb5_princ_component(krb5_context, krb5_principal, int ); +#endif +static DATA_BLOB unwrap_pac(TALLOC_CTX *mem_ctx, DATA_BLOB *auth_data) +{ + DATA_BLOB out; + DATA_BLOB pac_contents = data_blob(NULL, 0); + struct asn1_data data; + int data_type; + if (!auth_data->length) { + return data_blob(NULL, 0); + } + + asn1_load(&data, *auth_data); + asn1_start_tag(&data, ASN1_SEQUENCE(0)); + asn1_start_tag(&data, ASN1_SEQUENCE(0)); + asn1_start_tag(&data, ASN1_CONTEXT(0)); + asn1_read_Integer(&data, &data_type); + asn1_end_tag(&data); + asn1_start_tag(&data, ASN1_CONTEXT(1)); + asn1_read_OctetString(&data, &pac_contents); + asn1_end_tag(&data); + asn1_end_tag(&data); + asn1_end_tag(&data); + asn1_free(&data); + + out = data_blob_talloc(mem_ctx, pac_contents.data, pac_contents.length); + + data_blob_free(&pac_contents); + + return out; +} + +/********************************************************************************** + Try to verify a ticket using the system keytab... the system keytab has kvno -1 entries, so + it's more like what microsoft does... see comment in utils/net_ads.c in the + ads_keytab_add_entry function for details. +***********************************************************************************/ + +static krb5_error_code ads_keytab_verify_ticket(TALLOC_CTX *mem_ctx, krb5_context context, + krb5_auth_context auth_context, + const char *service, + const DATA_BLOB *ticket, krb5_data *p_packet, + krb5_ticket **pp_tkt, + krb5_keyblock *keyblock) +{ + krb5_error_code ret = 0; + krb5_keytab keytab = NULL; + krb5_kt_cursor kt_cursor; + krb5_keytab_entry kt_entry; + char *valid_princ_formats[7] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL }; + char *entry_princ_s = NULL; + const char *my_name, *my_fqdn; + int i; + int number_matched_principals = 0; + const char *last_error_message; + + /* Generate the list of principal names which we expect + * clients might want to use for authenticating to the file + * service. We allow name$,{host,cifs}/{name,fqdn,name.REALM}. */ + + my_name = lp_netbios_name(); + + my_fqdn = name_to_fqdn(mem_ctx, my_name); + + asprintf(&valid_princ_formats[0], "%s$@%s", my_name, lp_realm()); + asprintf(&valid_princ_formats[1], "host/%s@%s", my_name, lp_realm()); + asprintf(&valid_princ_formats[2], "host/%s@%s", my_fqdn, lp_realm()); + asprintf(&valid_princ_formats[3], "host/%s.%s@%s", my_name, lp_realm(), lp_realm()); + asprintf(&valid_princ_formats[4], "cifs/%s@%s", my_name, lp_realm()); + asprintf(&valid_princ_formats[5], "cifs/%s@%s", my_fqdn, lp_realm()); + asprintf(&valid_princ_formats[6], "cifs/%s.%s@%s", my_name, lp_realm(), lp_realm()); + + ZERO_STRUCT(kt_entry); + ZERO_STRUCT(kt_cursor); + + ret = krb5_kt_default(context, &keytab); + if (ret) { + DEBUG(1, ("ads_keytab_verify_ticket: krb5_kt_default failed (%s)\n", + smb_get_krb5_error_message(context, ret, mem_ctx))); + goto out; + } + + /* Iterate through the keytab. For each key, if the principal + * name case-insensitively matches one of the allowed formats, + * try verifying the ticket using that principal. */ + + ret = krb5_kt_start_seq_get(context, keytab, &kt_cursor); + if (ret) { + last_error_message = smb_get_krb5_error_message(context, ret, mem_ctx); + DEBUG(1, ("ads_keytab_verify_ticket: krb5_kt_start_seq_get failed (%s)\n", + last_error_message)); + goto out; + } + + ret = krb5_kt_start_seq_get(context, keytab, &kt_cursor); + if (ret != KRB5_KT_END && ret != ENOENT ) { + ret = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN; /* Pick an error... */ + while (ret && (krb5_kt_next_entry(context, keytab, &kt_entry, &kt_cursor) == 0)) { + krb5_error_code upn_ret; + upn_ret = krb5_unparse_name(context, kt_entry.principal, &entry_princ_s); + if (upn_ret) { + last_error_message = smb_get_krb5_error_message(context, ret, mem_ctx); + DEBUG(1, ("ads_keytab_verify_ticket: krb5_unparse_name failed (%s)\n", + last_error_message)); + ret = upn_ret; + break; + } + for (i = 0; i < ARRAY_SIZE(valid_princ_formats); i++) { + if (!strequal(entry_princ_s, valid_princ_formats[i])) { + continue; + } + + number_matched_principals++; + p_packet->length = ticket->length; + p_packet->data = (krb5_pointer)ticket->data; + *pp_tkt = NULL; + ret = krb5_rd_req(context, &auth_context, p_packet, kt_entry.principal, keytab, NULL, pp_tkt); + if (ret) { + last_error_message = smb_get_krb5_error_message(context, ret, mem_ctx); + DEBUG(10, ("ads_keytab_verify_ticket: krb5_rd_req(%s) failed: %s\n", + entry_princ_s, last_error_message)); + } else { + DEBUG(3,("ads_keytab_verify_ticket: krb5_rd_req succeeded for principal %s\n", + entry_princ_s)); + break; + } + } + + /* Free the name we parsed. */ + krb5_free_unparsed_name(context, entry_princ_s); + entry_princ_s = NULL; + + /* Free the entry we just read. */ + smb_krb5_kt_free_entry(context, &kt_entry); + ZERO_STRUCT(kt_entry); + } + krb5_kt_end_seq_get(context, keytab, &kt_cursor); + } + + ZERO_STRUCT(kt_cursor); + + out: + + if (ret) { + if (!number_matched_principals) { + DEBUG(3, ("ads_keytab_verify_ticket: no keytab principals matched expected file service name.\n")); + } else { + DEBUG(3, ("ads_keytab_verify_ticket: krb5_rd_req failed for all %d matched keytab principals\n", + number_matched_principals)); + } + DEBUG(3, ("ads_keytab_verify_ticket: last error: %s\n", last_error_message)); + } + + if (entry_princ_s) { + krb5_free_unparsed_name(context, entry_princ_s); + } + + { + krb5_keytab_entry zero_kt_entry; + ZERO_STRUCT(zero_kt_entry); + if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) { + smb_krb5_kt_free_entry(context, &kt_entry); + } + } + + { + krb5_kt_cursor zero_csr; + ZERO_STRUCT(zero_csr); + if ((memcmp(&kt_cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) { + krb5_kt_end_seq_get(context, keytab, &kt_cursor); + } + } + + if (keytab) { + krb5_kt_close(context, keytab); + } + + return ret; +} + +/********************************************************************************** + Try to verify a ticket using the secrets.tdb. +***********************************************************************************/ + +static krb5_error_code ads_secrets_verify_ticket(TALLOC_CTX *mem_ctx, krb5_context context, + krb5_auth_context auth_context, + krb5_principal host_princ, + const DATA_BLOB *ticket, krb5_data *p_packet, + krb5_ticket **pp_tkt, + krb5_keyblock *keyblock) +{ + krb5_error_code ret = 0; + krb5_error_code our_ret; + krb5_data password; + krb5_enctype *enctypes = NULL; + int i; + const struct ldb_val *password_v; + struct ldb_context *ldb; + int ldb_ret; + struct ldb_message **msgs; + const char *base_dn = SECRETS_PRIMARY_DOMAIN_DN; + const char *attrs[] = { + "secret", + NULL + }; + + ZERO_STRUCTP(keyblock); + + /* Local secrets are stored in secrets.ldb */ + ldb = secrets_db_connect(mem_ctx); + if (!ldb) { + return ENOENT; + } + + /* search for the secret record */ + ldb_ret = gendb_search(ldb, + mem_ctx, base_dn, &msgs, attrs, + SECRETS_PRIMARY_REALM_FILTER, + lp_realm()); + if (ldb_ret == 0) { + DEBUG(1, ("Could not find domain join record for %s\n", + lp_realm())); + return ENOENT; + } else if (ldb_ret != 1) { + DEBUG(1, ("Found %d records matching cn=%s under DN %s\n", ldb_ret, + lp_realm(), base_dn)); + return ENOENT; + } + + password_v = ldb_msg_find_ldb_val(msgs[0], "secret"); + + password.data = password_v->data; + password.length = password_v->length; + + /* CIFS doesn't use addresses in tickets. This would break NAT. JRA */ + + if ((ret = get_kerberos_allowed_etypes(context, &enctypes))) { + DEBUG(1,("ads_secrets_verify_ticket: krb5_get_permitted_enctypes failed (%s)\n", + error_message(ret))); + return ret; + } + + p_packet->length = ticket->length; + p_packet->data = (krb5_pointer)ticket->data; + + /* We need to setup a auth context with each possible encoding type in turn. */ + + ret = KRB5_BAD_ENCTYPE; + for (i=0;enctypes[i];i++) { + krb5_keyblock *key = NULL; + + if (!(key = malloc_p(krb5_keyblock))) { + break; + } + + if (create_kerberos_key_from_string(context, host_princ, &password, key, enctypes[i])) { + SAFE_FREE(key); + continue; + } + + krb5_auth_con_setuseruserkey(context, auth_context, key); + + krb5_free_keyblock(context, key); + + our_ret = krb5_rd_req(context, &auth_context, p_packet, + NULL, + NULL, NULL, pp_tkt); + if (!our_ret) { + + DEBUG(10,("ads_secrets_verify_ticket: enc type [%u] decrypted message !\n", + (unsigned int)enctypes[i] )); + ret = our_ret; + break; + } + + DEBUG((our_ret != KRB5_BAD_ENCTYPE) ? 3 : 10, + ("ads_secrets_verify_ticket: enc type [%u] failed to decrypt with error %s\n", + (unsigned int)enctypes[i], smb_get_krb5_error_message(context, our_ret, mem_ctx))); + + if (our_ret != KRB5_BAD_ENCTYPE) { + ret = our_ret; + } + } + + free_kerberos_etypes(context, enctypes); + + return ret; +} + +/********************************************************************************** + Verify an incoming ticket and parse out the principal name and + authorization_data if available. +***********************************************************************************/ + + NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx, + krb5_context context, + krb5_auth_context auth_context, + const char *realm, const char *service, + const DATA_BLOB *ticket, + char **principal, DATA_BLOB *auth_data, + DATA_BLOB *ap_rep, + krb5_keyblock *keyblock) +{ + NTSTATUS sret = NT_STATUS_LOGON_FAILURE; + krb5_data packet; + krb5_ticket *tkt = NULL; + krb5_rcache rcache = NULL; + int ret; + + krb5_principal host_princ = NULL; + char *host_princ_s = NULL; + BOOL got_replay_mutex = False; + + char *malloc_principal; + + ZERO_STRUCT(packet); + ZERO_STRUCTP(auth_data); + ZERO_STRUCTP(ap_rep); + + /* This whole process is far more complex than I would + like. We have to go through all this to allow us to store + the secret internally, instead of using /etc/krb5.keytab */ + + asprintf(&host_princ_s, "%s$", lp_netbios_name()); + strlower_m(host_princ_s); + ret = krb5_parse_name(context, host_princ_s, &host_princ); + if (ret) { + DEBUG(1,("ads_verify_ticket: krb5_parse_name(%s) failed (%s)\n", + host_princ_s, error_message(ret))); + goto out; + } + + + /* Lock a mutex surrounding the replay as there is no locking in the MIT krb5 + * code surrounding the replay cache... */ + + if (!grab_server_mutex("replay cache mutex")) { + DEBUG(1,("ads_verify_ticket: unable to protect replay cache with mutex.\n")); + goto out; + } + + got_replay_mutex = True; + + /* + * JRA. We must set the rcache here. This will prevent replay attacks. + */ + + ret = krb5_get_server_rcache(context, krb5_princ_component(context, host_princ, 0), &rcache); + if (ret) { + DEBUG(1,("ads_verify_ticket: krb5_get_server_rcache failed (%s)\n", error_message(ret))); + goto out; + } + + ret = krb5_auth_con_setrcache(context, auth_context, rcache); + if (ret) { + DEBUG(1,("ads_verify_ticket: krb5_auth_con_setrcache failed (%s)\n", error_message(ret))); + goto out; + } + + ret = ads_keytab_verify_ticket(mem_ctx, context, auth_context, + service, ticket, &packet, &tkt, keyblock); + if (ret) { + DEBUG(10, ("ads_secrets_verify_ticket: using host principal: [%s]\n", host_princ_s)); + ret = ads_secrets_verify_ticket(mem_ctx, context, auth_context, + host_princ, ticket, + &packet, &tkt, keyblock); + } + + release_server_mutex(); + got_replay_mutex = False; + + if (ret) { + DEBUG(3,("ads_verify_ticket: krb5_rd_req with auth failed (%s)\n", + smb_get_krb5_error_message(context, ret, mem_ctx))); + goto out; + } + + ret = krb5_mk_rep(context, auth_context, &packet); + if (ret) { + DEBUG(3,("ads_verify_ticket: Failed to generate mutual authentication reply (%s)\n", + smb_get_krb5_error_message(context, ret, mem_ctx))); + goto out; + } + + *ap_rep = data_blob_talloc(mem_ctx, packet.data, packet.length); + SAFE_FREE(packet.data); + packet.length = 0; + +#if 0 + file_save("/tmp/ticket.dat", ticket->data, ticket->length); +#endif + + *auth_data = get_auth_data_from_tkt(mem_ctx, tkt); + + *auth_data = unwrap_pac(mem_ctx, auth_data); + +#if 0 + if (tkt->enc_part2) { + file_save("/tmp/authdata.dat", + tkt->enc_part2->authorization_data[0]->contents, + tkt->enc_part2->authorization_data[0]->length); + } +#endif + + if ((ret = krb5_unparse_name(context, get_principal_from_tkt(tkt), + &malloc_principal))) { + DEBUG(3,("ads_verify_ticket: krb5_unparse_name failed (%s)\n", + smb_get_krb5_error_message(context, ret, mem_ctx))); + sret = NT_STATUS_LOGON_FAILURE; + goto out; + } + + *principal = talloc_strdup(mem_ctx, malloc_principal); + SAFE_FREE(malloc_principal); + if (!principal) { + DEBUG(3,("ads_verify_ticket: talloc_strdup() failed\n")); + sret = NT_STATUS_NO_MEMORY; + goto out; + } + + sret = NT_STATUS_OK; + + out: + + if (got_replay_mutex) { + release_server_mutex(); + } + + if (!NT_STATUS_IS_OK(sret)) { + data_blob_free(auth_data); + } + + if (!NT_STATUS_IS_OK(sret)) { + data_blob_free(ap_rep); + } + + if (host_princ) { + krb5_free_principal(context, host_princ); + } + + if (tkt != NULL) { + krb5_free_ticket(context, tkt); + } + + SAFE_FREE(host_princ_s); + + return sret; +} + +#endif /* HAVE_KRB5 */ |