trigger: expose trigger owner uid

[lttng-tools.git] / src / common / trigger.c

/*
 * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 */

#include <lttng/trigger/trigger-internal.h>
#include <lttng/condition/condition-internal.h>
#include <lttng/action/action-internal.h>
#include <common/credentials.h>
#include <common/payload.h>
#include <common/payload-view.h>
#include <common/error.h>
#include <common/optional.h>
#include <assert.h>

LTTNG_HIDDEN
bool lttng_trigger_validate(struct lttng_trigger *trigger)
{
	bool valid;

	if (!trigger) {
		valid = false;
		goto end;
	}

	if (!trigger->creds.uid.is_set) {
		valid = false;
		goto end;
	}

	valid = lttng_condition_validate(trigger->condition) &&
			lttng_action_validate(trigger->action);
end:
	return valid;
}

struct lttng_trigger *lttng_trigger_create(
		struct lttng_condition *condition,
		struct lttng_action *action)
{
	struct lttng_trigger *trigger = NULL;

	if (!condition || !action) {
		goto end;
	}

	trigger = zmalloc(sizeof(struct lttng_trigger));
	if (!trigger) {
		goto end;
	}

	urcu_ref_init(&trigger->ref);

	lttng_condition_get(condition);
	trigger->condition = condition;

	lttng_action_get(action);
	trigger->action = action;

end:
	return trigger;
}

/*
 * Note: the lack of reference counting 'get' on the condition object is normal.
 * This API was exposed as such in 2.11. The client is not expected to call
 * lttng_condition_destroy on the returned object.
 */
struct lttng_condition *lttng_trigger_get_condition(
		struct lttng_trigger *trigger)
{
	return trigger ? trigger->condition : NULL;
}

LTTNG_HIDDEN
const struct lttng_condition *lttng_trigger_get_const_condition(
		const struct lttng_trigger *trigger)
{
	return trigger->condition;
}


/*
 * Note: the lack of reference counting 'get' on the action object is normal.
 * This API was exposed as such in 2.11. The client is not expected to call
 * lttng_action_destroy on the returned object.
 */
struct lttng_action *lttng_trigger_get_action(
		struct lttng_trigger *trigger)
{
	return trigger ? trigger->action : NULL;
}

LTTNG_HIDDEN
const struct lttng_action *lttng_trigger_get_const_action(
		const struct lttng_trigger *trigger)
{
	return trigger->action;
}

static void trigger_destroy_ref(struct urcu_ref *ref)
{
	struct lttng_trigger *trigger =
			container_of(ref, struct lttng_trigger, ref);
	struct lttng_action *action = lttng_trigger_get_action(trigger);
	struct lttng_condition *condition =
			lttng_trigger_get_condition(trigger);

	assert(action);
	assert(condition);

	/* Release ownership. */
	lttng_action_put(action);
	lttng_condition_put(condition);

	free(trigger);
}

void lttng_trigger_destroy(struct lttng_trigger *trigger)
{
	lttng_trigger_put(trigger);
}

LTTNG_HIDDEN
ssize_t lttng_trigger_create_from_payload(
		struct lttng_payload_view *src_view,
		struct lttng_trigger **trigger)
{
	ssize_t ret, offset = 0, condition_size, action_size;
	struct lttng_condition *condition = NULL;
	struct lttng_action *action = NULL;
	const struct lttng_trigger_comm *trigger_comm;
	struct lttng_credentials creds = {
		.uid = LTTNG_OPTIONAL_INIT_UNSET,
		.gid = LTTNG_OPTIONAL_INIT_UNSET,
	};

	if (!src_view || !trigger) {
		ret = -1;
		goto end;
	}

	/* lttng_trigger_comm header */
	trigger_comm = (typeof(trigger_comm)) src_view->buffer.data;

	/* Set the trigger's creds. */
	if (trigger_comm->uid > (uint64_t) ((uid_t) -1)) {
		/* UID out of range for this platform. */
		ret = -1;
		goto end;
	}

	LTTNG_OPTIONAL_SET(&creds.uid, trigger_comm->uid);

	offset += sizeof(*trigger_comm);
	{
		/* struct lttng_condition */
		struct lttng_payload_view condition_view =
				lttng_payload_view_from_view(
						src_view, offset, -1);

		condition_size = lttng_condition_create_from_payload(&condition_view,
				&condition);
	}

	if (condition_size < 0) {
		ret = condition_size;
		goto end;
	}

	offset += condition_size;
	{
		/* struct lttng_action */
		struct lttng_payload_view action_view =
				lttng_payload_view_from_view(
					src_view, offset, -1);

		action_size = lttng_action_create_from_payload(&action_view, &action);
	}

	if (action_size < 0) {
		ret = action_size;
		goto end;
	}
	offset += action_size;

	/* Unexpected size of inner-elements; the buffer is corrupted. */
	if ((ssize_t) trigger_comm->length != condition_size + action_size) {
		ret = -1;
		goto error;
	}

	*trigger = lttng_trigger_create(condition, action);
	if (!*trigger) {
		ret = -1;
		goto error;
	}

	lttng_trigger_set_credentials(*trigger, &creds);

	/*
	 * The trigger object owns references to the action and condition
	 * objects.
	 */
	lttng_condition_put(condition);
	condition = NULL;

	lttng_action_put(action);
	action = NULL;

	ret = offset;

error:
	lttng_condition_destroy(condition);
	lttng_action_destroy(action);
end:
	return ret;
}

/*
 * Both elements are stored contiguously, see their "*_comm" structure
 * for the detailed format.
 */
LTTNG_HIDDEN
int lttng_trigger_serialize(struct lttng_trigger *trigger,
		struct lttng_payload *payload)
{
	int ret;
	size_t header_offset, size_before_payload;
	struct lttng_trigger_comm trigger_comm = {};
	struct lttng_trigger_comm *header;
	const struct lttng_credentials *creds = NULL;

	creds = lttng_trigger_get_credentials(trigger);
	assert(creds);

	trigger_comm.uid = LTTNG_OPTIONAL_GET(creds->uid);

	header_offset = payload->buffer.size;
	ret = lttng_dynamic_buffer_append(&payload->buffer, &trigger_comm,
			sizeof(trigger_comm));
	if (ret) {
		goto end;
	}

	size_before_payload = payload->buffer.size;
	ret = lttng_condition_serialize(trigger->condition, payload);
	if (ret) {
		goto end;
	}

	ret = lttng_action_serialize(trigger->action, payload);
	if (ret) {
		goto end;
	}

	/* Update payload size. */
	header = (typeof(header)) (payload->buffer.data + header_offset);
	header->length = payload->buffer.size - size_before_payload;
end:
	return ret;
}

LTTNG_HIDDEN
void lttng_trigger_get(struct lttng_trigger *trigger)
{
	urcu_ref_get(&trigger->ref);
}

LTTNG_HIDDEN
void lttng_trigger_put(struct lttng_trigger *trigger)
{
	if (!trigger) {
		return;
	}

	urcu_ref_put(&trigger->ref , trigger_destroy_ref);
}

LTTNG_HIDDEN
const struct lttng_credentials *lttng_trigger_get_credentials(
		const struct lttng_trigger *trigger)
{
	return &trigger->creds;
}

LTTNG_HIDDEN
void lttng_trigger_set_credentials(struct lttng_trigger *trigger,
		const struct lttng_credentials *creds)
{
	assert(creds);
	trigger->creds = *creds;
}

enum lttng_trigger_status lttng_trigger_set_owner_uid(
		struct lttng_trigger *trigger, uid_t uid)
{
	enum lttng_trigger_status ret = LTTNG_TRIGGER_STATUS_OK;
	const struct lttng_credentials creds = {
		.uid = LTTNG_OPTIONAL_INIT_VALUE(uid),
		.gid = LTTNG_OPTIONAL_INIT_UNSET,
	};

	if (!trigger) {
		ret = LTTNG_TRIGGER_STATUS_INVALID;
		goto end;
	}

	/* Client-side validation only to report a clearer error. */
	if (geteuid() != 0) {
		ret = LTTNG_TRIGGER_STATUS_PERMISSION_DENIED;
		goto end;
	}

	lttng_trigger_set_credentials(trigger, &creds);

end:
	return ret;
}

enum lttng_trigger_status lttng_trigger_get_owner_uid(
		const struct lttng_trigger *trigger, uid_t *uid)
{
	enum lttng_trigger_status ret = LTTNG_TRIGGER_STATUS_OK;
	const struct lttng_credentials *creds = NULL;

	if (!trigger || !uid ) {
		ret = LTTNG_TRIGGER_STATUS_INVALID;
		goto end;
	}

	if (!trigger->creds.uid.is_set ) {
		ret = LTTNG_TRIGGER_STATUS_UNSET;
		goto end;
	}

	creds = lttng_trigger_get_credentials(trigger);
	*uid = lttng_credentials_get_uid(creds);

end:
	return ret;
}