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lib/libcasper/libcasper/service.c

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/*-
* Copyright (c) 2013 The FreeBSD Foundation
* Copyright (c) 2015 Mariusz Zaborski <oshogbo@FreeBSD.org>
* All rights reserved.
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/nv.h>
#include <assert.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include "libcasper.h"
#include "libcasper_impl.h"
/*
* Currently there is only one service_connection per service.
* In the future we may want multiple connections from multiple clients
* per one service instance, but it has to be carefully designed.
* The problem is that we may restrict/sandbox service instance according
* to the limits provided. When new connection comes in with different
* limits we won't be able to access requested resources.
* Not to mention one process will serve to mutiple mutually untrusted
* clients and compromise of this service instance by one of its clients
* can lead to compromise of the other clients.
*/
/*
* Client connections to the given service.
*/
#define SERVICE_CONNECTION_MAGIC 0x5e91c0ec
struct service_connection {
int sc_magic;
cap_channel_t *sc_chan;
nvlist_t *sc_limits;
TAILQ_ENTRY(service_connection) sc_next;
};
#define SERVICE_MAGIC 0x5e91ce
struct service {
int s_magic;
char *s_name;
service_limit_func_t *s_limit;
service_command_func_t *s_command;
TAILQ_HEAD(, service_connection) s_connections;
};
struct service *
service_alloc(const char *name, service_limit_func_t *limitfunc,
service_command_func_t *commandfunc)
{
struct service *service;
service = malloc(sizeof(*service));
if (service == NULL)
return (NULL);
service->s_name = strdup(name);
if (service->s_name == NULL) {
free(service);
return (NULL);
}
service->s_limit = limitfunc;
service->s_command = commandfunc;
TAILQ_INIT(&service->s_connections);
service->s_magic = SERVICE_MAGIC;
return (service);
}
void
service_free(struct service *service)
{
struct service_connection *sconn;
assert(service->s_magic == SERVICE_MAGIC);
service->s_magic = 0;
while ((sconn = service_connection_first(service)) != NULL)
service_connection_remove(service, sconn);
free(service->s_name);
free(service);
}
struct service_connection *
service_connection_add(struct service *service, int sock,
const nvlist_t *limits)
{
struct service_connection *sconn;
int serrno;
assert(service->s_magic == SERVICE_MAGIC);
sconn = malloc(sizeof(*sconn));
if (sconn == NULL)
return (NULL);
sconn->sc_chan = cap_wrap(sock);
if (sconn->sc_chan == NULL) {
serrno = errno;
free(sconn);
errno = serrno;
return (NULL);
}
if (limits == NULL) {
sconn->sc_limits = NULL;
} else {
sconn->sc_limits = nvlist_clone(limits);
if (sconn->sc_limits == NULL) {
serrno = errno;
(void)cap_unwrap(sconn->sc_chan);
free(sconn);
errno = serrno;
return (NULL);
}
}
sconn->sc_magic = SERVICE_CONNECTION_MAGIC;
TAILQ_INSERT_TAIL(&service->s_connections, sconn, sc_next);
return (sconn);
}
void
service_connection_remove(struct service *service,
struct service_connection *sconn)
{
assert(service->s_magic == SERVICE_MAGIC);
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
TAILQ_REMOVE(&service->s_connections, sconn, sc_next);
sconn->sc_magic = 0;
nvlist_destroy(sconn->sc_limits);
cap_close(sconn->sc_chan);
free(sconn);
}
int
service_connection_clone(struct service *service,
struct service_connection *sconn)
{
struct service_connection *newsconn;
int serrno, sock[2];
if (socketpair(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, sock) < 0)
return (-1);
newsconn = service_connection_add(service, sock[0],
service_connection_get_limits(sconn));
if (newsconn == NULL) {
serrno = errno;
close(sock[0]);
close(sock[1]);
errno = serrno;
return (-1);
}
return (sock[1]);
}
struct service_connection *
service_connection_first(struct service *service)
{
struct service_connection *sconn;
assert(service->s_magic == SERVICE_MAGIC);
sconn = TAILQ_FIRST(&service->s_connections);
assert(sconn == NULL ||
sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
return (sconn);
}
struct service_connection *
service_connection_next(struct service_connection *sconn)
{
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
sconn = TAILQ_NEXT(sconn, sc_next);
assert(sconn == NULL ||
sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
return (sconn);
}
cap_channel_t *
service_connection_get_chan(const struct service_connection *sconn)
{
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
return (sconn->sc_chan);
}
int
service_connection_get_sock(const struct service_connection *sconn)
{
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
return (cap_sock(sconn->sc_chan));
}
const nvlist_t *
service_connection_get_limits(const struct service_connection *sconn)
{
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
return (sconn->sc_limits);
}
void
service_connection_set_limits(struct service_connection *sconn,
nvlist_t *limits)
{
assert(sconn->sc_magic == SERVICE_CONNECTION_MAGIC);
nvlist_destroy(sconn->sc_limits);
sconn->sc_limits = limits;
}
void
service_message(struct service *service, struct service_connection *sconn)
{
nvlist_t *nvlin, *nvlout;
const char *cmd;
int error;
nvlin = cap_recv_nvlist(service_connection_get_chan(sconn), 0);
if (nvlin == NULL) {
service_connection_remove(service, sconn);
return;
}
error = EDOOFUS;
nvlout = nvlist_create(0);
cmd = nvlist_get_string(nvlin, "cmd");
if (strcmp(cmd, "limit_set") == 0) {
nvlist_t *nvllim;
nvllim = nvlist_take_nvlist(nvlin, "limits");
if (service->s_limit == NULL) {
error = EOPNOTSUPP;
} else {
error = service->s_limit(
service_connection_get_limits(sconn), nvllim);
}
if (error == 0) {
service_connection_set_limits(sconn, nvllim);
/* Function consumes nvllim. */
} else {
nvlist_destroy(nvllim);
}
} else if (strcmp(cmd, "limit_get") == 0) {
const nvlist_t *nvllim;
nvllim = service_connection_get_limits(sconn);
if (nvllim != NULL)
nvlist_add_nvlist(nvlout, "limits", nvllim);
else
nvlist_add_null(nvlout, "limits");
error = 0;
} else if (strcmp(cmd, "clone") == 0) {
int sock;
sock = service_connection_clone(service, sconn);
if (sock == -1) {
error = errno;
} else {
nvlist_move_descriptor(nvlout, "sock", sock);
error = 0;
}
} else {
error = service->s_command(cmd,
service_connection_get_limits(sconn), nvlin, nvlout);
}
nvlist_destroy(nvlin);
nvlist_add_number(nvlout, "error", (uint64_t)error);
if (cap_send_nvlist(service_connection_get_chan(sconn), nvlout) == -1)
service_connection_remove(service, sconn);
nvlist_destroy(nvlout);
}
static int
fd_add(fd_set *fdsp, int maxfd, int fd)
{
FD_SET(fd, fdsp);
return (fd > maxfd ? fd : maxfd);
}
const char *
service_name(struct service *service)
{
assert(service->s_magic == SERVICE_MAGIC);
return (service->s_name);
}
void
service_start(struct service *service, int sock)
{
struct service_connection *sconn, *sconntmp;
fd_set fds;
int maxfd, nfds;
assert(service != NULL);
assert(service->s_magic == SERVICE_MAGIC);
setproctitle("%s", service->s_name);
if (service_connection_add(service, sock, NULL) == NULL)
exit(1);
for (;;) {
FD_ZERO(&fds);
maxfd = -1;
for (sconn = service_connection_first(service); sconn != NULL;
sconn = service_connection_next(sconn)) {
maxfd = fd_add(&fds, maxfd,
service_connection_get_sock(sconn));
}
assert(maxfd >= 0);
assert(maxfd + 1 <= (int)FD_SETSIZE);
nfds = select(maxfd + 1, &fds, NULL, NULL, NULL);
if (nfds < 0) {
if (errno != EINTR)
exit(1);
continue;
} else if (nfds == 0) {
/* Timeout. */
abort();
}
for (sconn = service_connection_first(service); sconn != NULL;
sconn = sconntmp) {
/*
* Prepare for connection to be removed from the list
* on failure.
*/
sconntmp = service_connection_next(sconn);
if (FD_ISSET(service_connection_get_sock(sconn), &fds))
service_message(service, sconn);
}
if (service_connection_first(service) == NULL) {
/*
* No connections left, exiting.
*/
break;
}
}
exit(0);
}