diff options
author | Simo Sorce <idra@samba.org> | 2012-03-30 19:33:53 -0400 |
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committer | Andreas Schneider <asn@samba.org> | 2012-04-12 12:06:42 +0200 |
commit | b226955587ee3a45c25bef2783e13e82d2f9048c (patch) | |
tree | 2f22a2773c277809ea6bccbd70339416e91fd774 /source4/auth/kerberos/srv_keytab.c | |
parent | 7d203f70aed948f40de0e5057e2289bb5e15628f (diff) | |
download | samba-b226955587ee3a45c25bef2783e13e82d2f9048c.tar.gz samba-b226955587ee3a45c25bef2783e13e82d2f9048c.tar.bz2 samba-b226955587ee3a45c25bef2783e13e82d2f9048c.zip |
s4-auth-krb: Move keytab functions in a separate file.
Confine ldb dependency.
Signed-off-by: Andreas Schneider <asn@samba.org>
Diffstat (limited to 'source4/auth/kerberos/srv_keytab.c')
-rw-r--r-- | source4/auth/kerberos/srv_keytab.c | 726 |
1 files changed, 726 insertions, 0 deletions
diff --git a/source4/auth/kerberos/srv_keytab.c b/source4/auth/kerberos/srv_keytab.c new file mode 100644 index 0000000000..ade3339122 --- /dev/null +++ b/source4/auth/kerberos/srv_keytab.c @@ -0,0 +1,726 @@ +/* + Unix SMB/CIFS implementation. + + Kerberos utility functions + + 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 "auth/credentials/credentials.h" +#include "system/kerberos.h" +#include "auth/kerberos/kerberos.h" +#include "auth/kerberos/kerberos_srv_keytab.h" +#include "auth/kerberos/kerberos_util.h" +#include <ldb.h> +#include "param/secrets.h" + +static krb5_error_code principals_from_msg(TALLOC_CTX *parent_ctx, + struct ldb_message *msg, + struct smb_krb5_context *smb_krb5_context, + struct principal_container ***principals_out, + const char **error_string) +{ + unsigned int i; + krb5_error_code ret; + char *upper_realm; + const char *realm = ldb_msg_find_attr_as_string(msg, "realm", NULL); + const char *samAccountName = ldb_msg_find_attr_as_string(msg, + "samAccountName", NULL); + struct ldb_message_element *spn_el = ldb_msg_find_element(msg, + "servicePrincipalName"); + TALLOC_CTX *tmp_ctx; + struct principal_container **principals; + tmp_ctx = talloc_new(parent_ctx); + if (!tmp_ctx) { + *error_string = "Cannot allocate tmp_ctx"; + return ENOMEM; + } + + if (!realm) { + *error_string = "Cannot have a kerberos secret in " + "secrets.ldb without a realm"; + return EINVAL; + } + + upper_realm = strupper_talloc(tmp_ctx, realm); + if (!upper_realm) { + talloc_free(tmp_ctx); + *error_string = "Cannot allocate full upper case realm"; + return ENOMEM; + } + + principals = talloc_array(tmp_ctx, struct principal_container *, + spn_el ? (spn_el->num_values + 2) : 2); + + spn_el = ldb_msg_find_element(msg, "servicePrincipalName"); + for (i=0; spn_el && i < spn_el->num_values; i++) { + principals[i] = talloc(principals, struct principal_container); + if (!principals[i]) { + talloc_free(tmp_ctx); + *error_string = "Cannot allocate mem_ctx"; + return ENOMEM; + } + + principals[i]->smb_krb5_context = + talloc_reference(principals[i], smb_krb5_context); + principals[i]->string_form = + talloc_asprintf(principals[i], "%*.*s@%s", + (int)spn_el->values[i].length, + (int)spn_el->values[i].length, + (const char *)spn_el->values[i].data, + upper_realm); + if (!principals[i]->string_form) { + talloc_free(tmp_ctx); + *error_string = "Cannot allocate full samAccountName"; + return ENOMEM; + } + + ret = krb5_parse_name(smb_krb5_context->krb5_context, + principals[i]->string_form, + &principals[i]->principal); + + if (ret) { + talloc_free(tmp_ctx); + (*error_string) = smb_get_krb5_error_message( + smb_krb5_context->krb5_context, + ret, parent_ctx); + return ret; + } + + /* This song-and-dance effectivly puts the principal + * into talloc, so we can't loose it. */ + talloc_set_destructor(principals[i], free_principal); + } + + if (samAccountName) { + principals[i] = talloc(principals, struct principal_container); + if (!principals[i]) { + talloc_free(tmp_ctx); + *error_string = "Cannot allocate mem_ctx"; + return ENOMEM; + } + + principals[i]->smb_krb5_context = + talloc_reference(principals[i], smb_krb5_context); + principals[i]->string_form = + talloc_asprintf(parent_ctx, "%s@%s", + samAccountName, upper_realm); + if (!principals[i]->string_form) { + talloc_free(tmp_ctx); + *error_string = "Cannot allocate full samAccountName"; + return ENOMEM; + } + + ret = krb5_make_principal(smb_krb5_context->krb5_context, + &principals[i]->principal, + upper_realm, samAccountName, + NULL); + if (ret) { + talloc_free(tmp_ctx); + (*error_string) = smb_get_krb5_error_message( + smb_krb5_context->krb5_context, + ret, parent_ctx); + return ret; + } + + /* This song-and-dance effectively puts the principal + * into talloc, so we can't loose it. */ + talloc_set_destructor(principals[i], free_principal); + i++; + } + + principals[i] = NULL; + *principals_out = talloc_steal(parent_ctx, principals); + + talloc_free(tmp_ctx); + return ret; +} + +static krb5_error_code salt_principal_from_msg(TALLOC_CTX *parent_ctx, + struct ldb_message *msg, + struct smb_krb5_context *smb_krb5_context, + krb5_principal *salt_princ, + const char **error_string) +{ + const char *salt_principal = ldb_msg_find_attr_as_string(msg, + "saltPrincipal", NULL); + const char *samAccountName = ldb_msg_find_attr_as_string(msg, + "samAccountName", NULL); + const char *realm = ldb_msg_find_attr_as_string(msg, "realm", NULL); + + struct principal_container *mem_ctx; + krb5_error_code ret; + char *machine_username; + char *salt_body; + char *lower_realm; + char *upper_realm; + + TALLOC_CTX *tmp_ctx; + + if (salt_principal) { + return parse_principal(parent_ctx, salt_principal, + smb_krb5_context, salt_princ, + error_string); + } + + if (!samAccountName) { + (*error_string) = "Cannot determine salt principal, no " + "saltPrincipal or samAccountName specified"; + return EINVAL; + } + + + mem_ctx = talloc(parent_ctx, struct principal_container); + if (!mem_ctx) { + *error_string = "Cannot allocate mem_ctx"; + return ENOMEM; + } + + tmp_ctx = talloc_new(mem_ctx); + if (!tmp_ctx) { + talloc_free(mem_ctx); + *error_string = "Cannot allocate tmp_ctx"; + return ENOMEM; + } + + if (!realm) { + *error_string = "Cannot have a kerberos secret in " + "secrets.ldb without a realm"; + return EINVAL; + } + + machine_username = talloc_strdup(tmp_ctx, samAccountName); + if (!machine_username) { + talloc_free(mem_ctx); + *error_string = "Cannot duplicate samAccountName"; + return ENOMEM; + } + + if (machine_username[strlen(machine_username)-1] == '$') { + machine_username[strlen(machine_username)-1] = '\0'; + } + + lower_realm = strlower_talloc(tmp_ctx, realm); + if (!lower_realm) { + talloc_free(mem_ctx); + *error_string = "Cannot allocate to lower case realm"; + return ENOMEM; + } + + upper_realm = strupper_talloc(tmp_ctx, realm); + if (!upper_realm) { + talloc_free(mem_ctx); + *error_string = "Cannot allocate to upper case realm"; + return ENOMEM; + } + + salt_body = talloc_asprintf(tmp_ctx, "%s.%s", machine_username, + lower_realm); + talloc_free(lower_realm); + talloc_free(machine_username); + if (!salt_body) { + talloc_free(mem_ctx); + *error_string = "Cannot form salt principal body"; + return ENOMEM; + } + + ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ, + upper_realm, + "host", salt_body, NULL); + if (ret == 0) { + /* This song-and-dance effectively 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 = *salt_princ; + talloc_set_destructor(mem_ctx, free_principal); + } else { + (*error_string) = smb_get_krb5_error_message( + smb_krb5_context->krb5_context, + ret, parent_ctx); + } + talloc_free(tmp_ctx); + return ret; +} + +/* Translate between the Microsoft msDS-SupportedEncryptionTypes values + * and the IETF encryption type values */ +static krb5_enctype ms_suptype_to_ietf_enctype(uint32_t enctype_bitmap) +{ + switch (enctype_bitmap) { + case ENC_CRC32: + return ENCTYPE_DES_CBC_CRC; + case ENC_RSA_MD5: + return ENCTYPE_DES_CBC_MD5; + case ENC_RC4_HMAC_MD5: + return ENCTYPE_ARCFOUR_HMAC_MD5; + case ENC_HMAC_SHA1_96_AES128: + return ENCTYPE_AES128_CTS_HMAC_SHA1_96; + case ENC_HMAC_SHA1_96_AES256: + return ENCTYPE_AES256_CTS_HMAC_SHA1_96; + default: + return 0; + } +} + +/* Return an array of krb5_enctype values */ +static krb5_error_code ms_suptypes_to_ietf_enctypes(TALLOC_CTX *mem_ctx, + uint32_t enctype_bitmap, + krb5_enctype **enctypes) +{ + unsigned int i, j = 0; + *enctypes = talloc_zero_array(mem_ctx, krb5_enctype, + (8 * sizeof(enctype_bitmap)) + 1); + if (!*enctypes) { + return ENOMEM; + } + for (i = 0; i < (8 * sizeof(enctype_bitmap)); i++) { + uint32_t bit_value = (1 << i) & enctype_bitmap; + if (bit_value & enctype_bitmap) { + (*enctypes)[j] = ms_suptype_to_ietf_enctype(bit_value); + if (!(*enctypes)[j]) { + continue; + } + j++; + } + } + (*enctypes)[j] = 0; + return 0; +} + +static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx, + struct principal_container **principals, + krb5_principal salt_princ, + int kvno, + const char *password_s, + krb5_context krb5_context, + krb5_enctype *enctypes, + krb5_keytab keytab, + const char **error_string) +{ + unsigned int i, p; + krb5_error_code ret; + krb5_data password; + + password.data = discard_const_p(char *, password_s); + password.length = strlen(password_s); + + for (i = 0; enctypes[i]; i++) { + krb5_keytab_entry entry; + + ZERO_STRUCT(entry); + + ret = create_kerberos_key_from_string_direct(krb5_context, + salt_princ, &password, + &entry.keyblock, enctypes[i]); + if (ret != 0) { + return ret; + } + + entry.vno = kvno; + + for (p = 0; principals[p]; p++) { + entry.principal = principals[p]->principal; + ret = krb5_kt_add_entry(krb5_context, + keytab, &entry); + if (ret != 0) { + char *k5_error_string = + smb_get_krb5_error_message( + krb5_context, ret, NULL); + *error_string = talloc_asprintf(parent_ctx, + "Failed to add enctype %d entry for " + "%s(kvno %d) to keytab: %s\n", + (int)enctypes[i], + principals[p]->string_form, + kvno, k5_error_string); + + talloc_free(k5_error_string); + krb5_free_keyblock_contents(krb5_context, + &entry.keyblock); + return ret; + } + + DEBUG(5, ("Added %s(kvno %d) to keytab (enctype %d)\n", + principals[p]->string_form, kvno, + (int)enctypes[i])); + } + krb5_free_keyblock_contents(krb5_context, &entry.keyblock); + } + return 0; +} + +static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx, + struct ldb_message *msg, + struct principal_container **principals, + struct smb_krb5_context *smb_krb5_context, + krb5_keytab keytab, + bool add_old, + const char **error_string) +{ + krb5_error_code ret; + const char *password_s; + const char *old_secret; + int kvno; + uint32_t enctype_bitmap; + krb5_principal salt_princ; + krb5_enctype *enctypes; + TALLOC_CTX *mem_ctx = talloc_new(parent_ctx); + if (!mem_ctx) { + *error_string = "unable to allocate tmp_ctx for create_keytab"; + return ENOMEM; + } + + /* The salt used to generate these entries may be different however, + * fetch that */ + ret = salt_principal_from_msg(mem_ctx, msg, + smb_krb5_context, + &salt_princ, error_string); + if (ret) { + talloc_free(mem_ctx); + return ret; + } + + kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0); + + /* Finally, do the dance to get the password to put in the entry */ + password_s = ldb_msg_find_attr_as_string(msg, "secret", NULL); + + if (!password_s) { + /* There is no password here, so nothing to do */ + talloc_free(mem_ctx); + return 0; + } + + if (add_old && kvno != 0) { + old_secret = ldb_msg_find_attr_as_string(msg, + "priorSecret", NULL); + } else { + old_secret = NULL; + } + + enctype_bitmap = (uint32_t)ldb_msg_find_attr_as_int(msg, + "msDS-SupportedEncryptionTypes", + ENC_ALL_TYPES); + + ret = ms_suptypes_to_ietf_enctypes(mem_ctx, enctype_bitmap, &enctypes); + if (ret) { + *error_string = talloc_asprintf(parent_ctx, + "create_keytab: generating list of " + "encryption types failed (%s)\n", + smb_get_krb5_error_message( + smb_krb5_context->krb5_context, + ret, mem_ctx)); + talloc_free(mem_ctx); + return ret; + } + + ret = keytab_add_keys(mem_ctx, principals, + salt_princ, kvno, password_s, + smb_krb5_context->krb5_context, + enctypes, keytab, error_string); + if (ret) { + talloc_free(mem_ctx); + return ret; + } + + if (old_secret) { + ret = keytab_add_keys(mem_ctx, principals, + salt_princ, kvno - 1, old_secret, + smb_krb5_context->krb5_context, + enctypes, keytab, error_string); + if (ret) { + talloc_free(mem_ctx); + return ret; + } + } + + talloc_free(mem_ctx); + return ret; +} + +/* + * 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'. + */ + +static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx, + struct ldb_message *msg, + struct principal_container **principals, + bool delete_all_kvno, + krb5_context krb5_context, + krb5_keytab keytab, + bool *found_previous, + const char **error_string) +{ + krb5_error_code ret, ret2; + krb5_kt_cursor cursor; + int kvno; + TALLOC_CTX *mem_ctx = talloc_new(parent_ctx); + + if (!mem_ctx) { + return ENOMEM; + } + + *found_previous = false; + + kvno = ldb_msg_find_attr_as_int(msg, "msDS-KeyVersionNumber", 0); + + /* for each entry in the keytab */ + ret = krb5_kt_start_seq_get(krb5_context, keytab, &cursor); + switch (ret) { + case 0: + break; + case HEIM_ERR_OPNOTSUPP: + case ENOENT: + case KRB5_KT_END: + /* no point enumerating if there isn't anything here */ + talloc_free(mem_ctx); + return 0; + default: + *error_string = talloc_asprintf(parent_ctx, + "failed to open keytab for read of old entries: %s\n", + smb_get_krb5_error_message(krb5_context, + ret, mem_ctx)); + talloc_free(mem_ctx); + return ret; + } + + while (!ret) { + unsigned int i; + bool matched = false; + krb5_keytab_entry entry; + ret = krb5_kt_next_entry(krb5_context, keytab, + &entry, &cursor); + if (ret) { + break; + } + for (i = 0; principals[i]; i++) { + /* if it matches our principal */ + if (krb5_kt_compare(krb5_context, &entry, + principals[i]->principal, 0, 0)) { + matched = true; + break; + } + } + + if (!matched) { + /* Free the entry, + * it wasn't the one we were looking for anyway */ + krb5_kt_free_entry(krb5_context, &entry); + continue; + } + + /* delete it, if it is not kvno -1 */ + if (entry.vno != (kvno - 1 )) { + /* 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(krb5_context, keytab, &cursor); + + ret = krb5_kt_remove_entry(krb5_context, keytab, &entry); + krb5_kt_free_entry(krb5_context, &entry); + + /* Deleted: Restart from the top */ + ret2 = krb5_kt_start_seq_get(krb5_context, + keytab, &cursor); + if (ret2) { + krb5_kt_free_entry(krb5_context, &entry); + DEBUG(1, ("failed to restart enumeration of keytab: %s\n", + smb_get_krb5_error_message(krb5_context, + ret, mem_ctx))); + + talloc_free(mem_ctx); + return ret2; + } + + if (ret) { + break; + } + + } else { + *found_previous = true; + } + + /* Free the entry, we don't need it any more */ + krb5_kt_free_entry(krb5_context, &entry); + } + krb5_kt_end_seq_get(krb5_context, keytab, &cursor); + + switch (ret) { + case 0: + break; + case ENOENT: + case KRB5_KT_END: + ret = 0; + break; + default: + *error_string = talloc_asprintf(parent_ctx, + "failed in deleting old entries for principal: %s\n", + smb_get_krb5_error_message(krb5_context, + ret, mem_ctx)); + } + talloc_free(mem_ctx); + return ret; +} + +krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx, + struct smb_krb5_context *smb_krb5_context, + struct ldb_context *ldb, + struct ldb_message *msg, + bool delete_all_kvno, + const char **error_string) +{ + krb5_error_code ret; + bool found_previous; + TALLOC_CTX *mem_ctx = talloc_new(NULL); + struct keytab_container *keytab_container; + struct principal_container **principals; + const char *keytab_name; + + if (!mem_ctx) { + return ENOMEM; + } + + keytab_name = keytab_name_from_msg(mem_ctx, ldb, msg); + if (!keytab_name) { + return ENOENT; + } + + ret = smb_krb5_get_keytab_container(mem_ctx, smb_krb5_context, + keytab_name, &keytab_container); + + if (ret != 0) { + talloc_free(mem_ctx); + return ret; + } + + DEBUG(5, ("Opened keytab %s\n", keytab_name)); + + /* Get the principal we will store the new keytab entries under */ + ret = principals_from_msg(mem_ctx, msg, smb_krb5_context, + &principals, error_string); + + if (ret != 0) { + *error_string = talloc_asprintf(parent_ctx, + "Failed to load principals from ldb message: %s\n", + *error_string); + talloc_free(mem_ctx); + return ret; + } + + ret = remove_old_entries(mem_ctx, msg, principals, delete_all_kvno, + smb_krb5_context->krb5_context, + keytab_container->keytab, + &found_previous, error_string); + if (ret != 0) { + *error_string = talloc_asprintf(parent_ctx, + "Failed to remove old principals from keytab: %s\n", + *error_string); + talloc_free(mem_ctx); + return ret; + } + + if (!delete_all_kvno) { + /* Create a new keytab. If during the cleanout we found + * entires for kvno -1, then don't try and duplicate them. + * Otherwise, add kvno, and kvno -1 */ + + ret = create_keytab(mem_ctx, msg, principals, + smb_krb5_context, + keytab_container->keytab, + found_previous ? false : true, + error_string); + } + talloc_free(mem_ctx); + return ret; +} + +krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx, + struct cli_credentials *machine_account, + struct smb_krb5_context *smb_krb5_context, + struct keytab_container **keytab_container) +{ + krb5_error_code ret; + TALLOC_CTX *mem_ctx = talloc_new(parent_ctx); + const char *rand_string; + const char *keytab_name; + struct ldb_message *msg; + const char *error_string; + if (!mem_ctx) { + return ENOMEM; + } + + *keytab_container = talloc(mem_ctx, struct keytab_container); + + rand_string = generate_random_str(mem_ctx, 16); + if (!rand_string) { + talloc_free(mem_ctx); + return ENOMEM; + } + + keytab_name = talloc_asprintf(mem_ctx, "MEMORY:%s", + rand_string); + if (!keytab_name) { + talloc_free(mem_ctx); + return ENOMEM; + } + + ret = smb_krb5_get_keytab_container(mem_ctx, smb_krb5_context, + keytab_name, keytab_container); + if (ret) { + return ret; + } + + msg = ldb_msg_new(mem_ctx); + if (!msg) { + talloc_free(mem_ctx); + return ENOMEM; + } + ldb_msg_add_string(msg, "krb5Keytab", keytab_name); + ldb_msg_add_string(msg, "secret", + cli_credentials_get_password(machine_account)); + ldb_msg_add_string(msg, "samAccountName", + cli_credentials_get_username(machine_account)); + ldb_msg_add_string(msg, "realm", + cli_credentials_get_realm(machine_account)); + ldb_msg_add_fmt(msg, "msDS-KeyVersionNumber", "%d", + (int)cli_credentials_get_kvno(machine_account)); + + ret = smb_krb5_update_keytab(mem_ctx, smb_krb5_context, NULL, + msg, false, &error_string); + if (ret == 0) { + talloc_steal(parent_ctx, *keytab_container); + } else { + DEBUG(0, ("Failed to create in-memory keytab: %s\n", + error_string)); + *keytab_container = NULL; + } + talloc_free(mem_ctx); + return ret; +} |