kerberos_util.c

samba最新软件

static int create_keytab(TALLOC_CTX *parent_ctx,
			 struct cli_credentials *machine_account,
			 struct smb_krb5_context *smb_krb5_context,
			 const char **enctype_strings,
			 krb5_keytab keytab,
			 bool add_old) 
{
	krb5_error_code ret;
	const char *password_s;
	const char *old_secret;
	int kvno;
	krb5_principal salt_princ;
	krb5_principal princ;
	const char *princ_string;

	TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
	if (!mem_ctx) {
		return ENOMEM;
	}

	princ_string = cli_credentials_get_principal(machine_account, mem_ctx);
	/* Get the principal we will store the new keytab entries under */
	ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
	if (ret) {
		DEBUG(1,("create_keytab: makeing krb5 principal failed (%s)\n",
			 smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
						    ret, mem_ctx)));
		talloc_free(mem_ctx);
		return ret;
	}

	/* The salt used to generate these entries may be different however, fetch that */
	ret = salt_principal_from_credentials(mem_ctx, machine_account, 
					      smb_krb5_context, 
					      &salt_princ);
	if (ret) {
		DEBUG(1,("create_keytab: makeing salt principal failed (%s)\n",
			 smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
						    ret, mem_ctx)));
		talloc_free(mem_ctx);
		return ret;
	}

	/* Finally, do the dance to get the password to put in the entry */
	password_s = cli_credentials_get_password(machine_account);
	if (!password_s) {
		krb5_keytab_entry entry;
		const struct samr_Password *mach_pwd;

		if (!str_list_check(enctype_strings, "arcfour-hmac-md5")) {
			DEBUG(1, ("Asked to create keytab, but with only an NT hash supplied, "
				  "but not listing arcfour-hmac-md5 as an enc type to include in the keytab!\n"));
			talloc_free(mem_ctx);
			return EINVAL;
		}

		/* If we don't have the plaintext password, try for
		 * the MD4 password hash */
		mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
		if (!mach_pwd) {
			/* OK, nothing to do here */
			talloc_free(mem_ctx);
			return 0;
		}
		ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
					 ETYPE_ARCFOUR_HMAC_MD5,
					 mach_pwd->hash, sizeof(mach_pwd->hash), 
					 &entry.keyblock);
		if (ret) {
			DEBUG(1, ("create_keytab: krb5_keyblock_init failed: %s\n",
				  smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
							     ret, mem_ctx)));
			talloc_free(mem_ctx);
			return ret;
		}

		entry.principal = princ;
		entry.vno       = cli_credentials_get_kvno(machine_account);
		ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
		if (ret) {
			DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
				  cli_credentials_get_principal(machine_account, mem_ctx), 
				  smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
							     ret, mem_ctx)));
			talloc_free(mem_ctx);
			krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
			return ret;
		}
		
		DEBUG(5, ("Added %s(kvno %d) to keytab (arcfour-hmac-md5)\n", 
			  cli_credentials_get_principal(machine_account, mem_ctx),
			  cli_credentials_get_kvno(machine_account)));

		krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);

		/* Can't go any further, we only have this one key */
		talloc_free(mem_ctx);
		return 0;
	}
	
	kvno = cli_credentials_get_kvno(machine_account);
	/* good, we actually have the real plaintext */
	ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ, 
			      kvno, password_s, smb_krb5_context, 
			      enctype_strings, keytab);
	if (!ret) {
		talloc_free(mem_ctx);
		return ret;
	}

	if (!add_old || kvno == 0) {
		talloc_free(mem_ctx);
		return 0;
	}

	old_secret = cli_credentials_get_old_password(machine_account);
	if (!old_secret) {
		talloc_free(mem_ctx);
		return 0;
	}
	
	ret = keytab_add_keys(mem_ctx, princ_string, princ, salt_princ, 
			      kvno - 1, old_secret, smb_krb5_context, 
			      enctype_strings, keytab);
	if (!ret) {
		talloc_free(mem_ctx);
		return ret;
	}

	talloc_free(mem_ctx);
	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'.
 *
 */

static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
					  struct cli_credentials *machine_account,
					  struct smb_krb5_context *smb_krb5_context,
					  krb5_keytab keytab, bool *found_previous)
{
	krb5_error_code ret, ret2;
	krb5_kt_cursor cursor;
	krb5_principal princ;
	int kvno;
	TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
	const char *princ_string;
	if (!mem_ctx) {
		return ENOMEM;
	}

	*found_previous = false;
	princ_string = cli_credentials_get_principal(machine_account, mem_ctx);

	/* Get the principal we will store the new keytab entries under */
	ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
	if (ret) {
		DEBUG(1,("update_keytab: makeing krb5 principal failed (%s)\n",
			 smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
						    ret, mem_ctx)));
		talloc_free(mem_ctx);
		return ret;
	}

	kvno = cli_credentials_get_kvno(machine_account);

	/* for each entry in the keytab */
	ret = krb5_kt_start_seq_get(smb_krb5_context->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:
		DEBUG(1,("failed to open keytab for read of old entries: %s\n",
			 smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
						    ret, mem_ctx)));
		talloc_free(mem_ctx);
		return ret;
	}

	while (!ret) {
		krb5_keytab_entry entry;
		ret = krb5_kt_next_entry(smb_krb5_context->krb5_context, keytab, &entry, &cursor);
		if (ret) {
			break;
		}
		/* if it matches our principal */
		if (!krb5_kt_compare(smb_krb5_context->krb5_context, &entry, princ, 0, 0)) {
			/* Free the entry, it wasn't the one we were looking for anyway */
			krb5_kt_free_entry(smb_krb5_context->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 consistant.
			 *
			 * Also, the enumeration locks a FILE: keytab
			 */
		
			krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);

			ret = krb5_kt_remove_entry(smb_krb5_context->krb5_context, keytab, &entry);
			krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);

			/* Deleted: Restart from the top */
			ret2 = krb5_kt_start_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);
			if (ret2) {
				krb5_kt_free_entry(smb_krb5_context->krb5_context, &entry);
				DEBUG(1,("failed to restart enumeration of keytab: %s\n",
					 smb_get_krb5_error_message(smb_krb5_context->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(smb_krb5_context->krb5_context, &entry);
		
		
	}
	krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);

	switch (ret) {
	case 0:
		break;
	case ENOENT:
	case KRB5_KT_END:
		ret = 0;
		break;
	default:
		DEBUG(1,("failed in deleting old entries for principal: %s: %s\n",
			 princ_string, 
			 smb_get_krb5_error_message(smb_krb5_context->krb5_context, 
						    ret, mem_ctx)));
	}
	talloc_free(mem_ctx);
	return ret;
}

int smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
			   struct cli_credentials *machine_account,
			   struct smb_krb5_context *smb_krb5_context,
			   const char **enctype_strings,
			   struct keytab_container *keytab_container) 
{
	krb5_error_code ret;
	bool found_previous;
	TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
	if (!mem_ctx) {
		return ENOMEM;
	}

	ret = remove_old_entries(mem_ctx, machine_account, 
				 smb_krb5_context, keytab_container->keytab, &found_previous);
	if (ret != 0) {
		talloc_free(mem_ctx);
		return ret;
	}
	
	/* 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, machine_account, smb_krb5_context, 
			    enctype_strings, 
			    keytab_container->keytab, 
			    found_previous ? false : true);
	talloc_free(mem_ctx);
	return ret;
}

int smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
					   struct cli_credentials *machine_account,
					   struct smb_krb5_context *smb_krb5_context,
					   const char **enctype_strings,
					   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;
	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_open_keytab(mem_ctx, smb_krb5_context, keytab_name, keytab_container);
	if (ret) {
		return ret;
	}

	ret = smb_krb5_update_keytab(mem_ctx, machine_account, smb_krb5_context, enctype_strings, *keytab_container);
	if (ret == 0) {
		talloc_steal(parent_ctx, *keytab_container);
	} else {
		*keytab_container = NULL;
	}
	talloc_free(mem_ctx);
	return ret;
}