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|
/*-
* Copyright (c) 2012 The FreeBSD Foundation
* 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/capsicum.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/nv.h>
#include <assert.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <paths.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <libcapsicum.h>
#include <libcapsicum_impl.h>
#include <libcasper.h>
#include <libcasper_impl.h>
#include <msgio.h>
#include <pjdlog.h>
#include "msgio.h"
#include "zygote.h"
#define CASPERD_PIDFILE "/var/run/casperd.pid"
#define CASPERD_SERVCONFDIR "/etc/casper"
#define CASPERD_SOCKPATH "/var/run/casper"
typedef void service_function_t(struct service_connection *, const nvlist_t *,
nvlist_t *);
struct casper_service {
const char *cs_name;
const char *cs_execpath;
struct service *cs_service;
nvlist_t *cs_attrs;
TAILQ_ENTRY(casper_service) cs_next;
};
static TAILQ_HEAD(, casper_service) casper_services =
TAILQ_HEAD_INITIALIZER(casper_services);
#define SERVICE_IS_CORE(service) ((service)->cs_execpath == NULL)
static void service_external_execute(int chanfd);
#define KEEP_ERRNO(work) do { \
int _serrno; \
\
_serrno = errno; \
work; \
errno = _serrno; \
} while (0)
static struct casper_service *
service_find(const char *name)
{
struct casper_service *casserv;
TAILQ_FOREACH(casserv, &casper_services, cs_next) {
if (strcmp(casserv->cs_name, name) == 0)
break;
}
return (casserv);
}
/*
* Function always consumes the given attrs.
*/
static void
service_register(nvlist_t *attrs)
{
struct casper_service *casserv;
const char *name;
PJDLOG_ASSERT(nvlist_exists_string(attrs, "name"));
PJDLOG_ASSERT(nvlist_exists_string(attrs, "execpath") ||
(nvlist_exists_number(attrs, "commandfunc") &&
nvlist_exists_number(attrs, "limitfunc")));
name = nvlist_get_string(attrs, "name");
PJDLOG_ASSERT(name != NULL);
if (name[0] == '\0') {
pjdlog_error("Unable to register service with an empty name.");
nvlist_destroy(attrs);
return;
}
if (service_find(name) != NULL) {
pjdlog_error("Service \"%s\" is already registered.", name);
nvlist_destroy(attrs);
return;
}
casserv = malloc(sizeof(*casserv));
if (casserv == NULL) {
pjdlog_errno(LOG_ERR, "Unable to register service \"%s\"",
name);
nvlist_destroy(attrs);
return;
}
casserv->cs_name = name;
if (nvlist_exists_string(attrs, "execpath")) {
struct stat sb;
PJDLOG_ASSERT(!nvlist_exists_number(attrs, "commandfunc"));
PJDLOG_ASSERT(!nvlist_exists_number(attrs, "limitfunc"));
casserv->cs_service = NULL;
casserv->cs_execpath = nvlist_get_string(attrs, "execpath");
if (casserv->cs_execpath == NULL ||
casserv->cs_execpath[0] == '\0') {
pjdlog_error("Unable to register service with an empty execpath.");
free(casserv);
nvlist_destroy(attrs);
return;
}
if (stat(casserv->cs_execpath, &sb) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to register service \"%s\", problem with executable \"%s\"",
name, casserv->cs_execpath);
free(casserv);
nvlist_destroy(attrs);
return;
}
} else /* if (nvlist_exists_number(attrs, "commandfunc")) */ {
PJDLOG_ASSERT(!nvlist_exists_string(attrs, "execpath"));
casserv->cs_execpath = NULL;
casserv->cs_service = service_alloc(name,
(void *)(uintptr_t)nvlist_get_number(attrs, "limitfunc"),
(void *)(uintptr_t)nvlist_get_number(attrs, "commandfunc"));
if (casserv->cs_service == NULL) {
pjdlog_errno(LOG_ERR,
"Unable to register service \"%s\"", name);
free(casserv);
nvlist_destroy(attrs);
return;
}
}
casserv->cs_attrs = attrs;
TAILQ_INSERT_TAIL(&casper_services, casserv, cs_next);
pjdlog_debug(1, "Service %s successfully registered.",
casserv->cs_name);
}
static bool
casper_allowed_service(const nvlist_t *limits, const char *service)
{
if (limits == NULL)
return (true);
if (nvlist_exists_null(limits, service))
return (true);
return (false);
}
static int
casper_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
{
const char *name;
int type;
void *cookie;
cookie = NULL;
while ((name = nvlist_next(newlimits, &type, &cookie)) != NULL) {
if (type != NV_TYPE_NULL)
return (EINVAL);
if (!casper_allowed_service(oldlimits, name))
return (ENOTCAPABLE);
}
return (0);
}
static int
casper_command(const char *cmd, const nvlist_t *limits, nvlist_t *nvlin,
nvlist_t *nvlout)
{
struct casper_service *casserv;
const char *servname;
nvlist_t *nvl;
int chanfd, execfd, procfd, error;
if (strcmp(cmd, "open") != 0)
return (EINVAL);
if (!nvlist_exists_string(nvlin, "service"))
return (EINVAL);
servname = nvlist_get_string(nvlin, "service");
casserv = service_find(servname);
if (casserv == NULL)
return (ENOENT);
if (!casper_allowed_service(limits, servname))
return (ENOTCAPABLE);
#ifdef O_EXEC_WORKING
execfd = open(casserv->cs_execpath, O_EXEC);
#else
execfd = open(casserv->cs_execpath, O_RDONLY);
#endif
if (execfd < -1) {
error = errno;
pjdlog_errno(LOG_ERR,
"Unable to open executable '%s' of service '%s'",
casserv->cs_execpath, casserv->cs_name);
return (error);
}
if (zygote_clone(service_external_execute, &chanfd, &procfd) == -1) {
error = errno;
close(execfd);
return (error);
}
nvl = nvlist_create(0);
nvlist_add_string(nvl, "service", casserv->cs_name);
if (nvlist_exists_descriptor(nvlin, "stderrfd")) {
nvlist_move_descriptor(nvl, "stderrfd",
nvlist_take_descriptor(nvlin, "stderrfd"));
}
nvlist_move_descriptor(nvl, "execfd", execfd);
nvlist_move_descriptor(nvl, "procfd", procfd);
if (nvlist_send(chanfd, nvl) == -1) {
error = errno;
pjdlog_errno(LOG_ERR, "Unable to send nvlist");
nvlist_destroy(nvl);
close(chanfd);
return (error);
}
nvlist_destroy(nvl);
nvlist_move_descriptor(nvlout, "chanfd", chanfd);
return (0);
}
static void
fdswap(int *fd0, int *fd1)
{
int tmpfd;
PJDLOG_VERIFY((tmpfd = dup(*fd0)) != -1);
PJDLOG_VERIFY(dup2(*fd1, *fd0) != -1);
PJDLOG_VERIFY(dup2(tmpfd, *fd1) != -1);
close(tmpfd);
tmpfd = *fd0;
*fd0 = *fd1;
*fd1 = tmpfd;
}
static void
fdmove(int *oldfdp, int newfd)
{
if (*oldfdp != newfd) {
PJDLOG_VERIFY(dup2(*oldfdp, newfd) != -1);
close(*oldfdp);
*oldfdp = newfd;
}
}
static void
fdcloexec(int fd)
{
int flags;
flags = fcntl(fd, F_GETFD);
PJDLOG_ASSERT(flags != -1);
if ((flags & FD_CLOEXEC) != 0)
PJDLOG_VERIFY(fcntl(fd, F_SETFD, flags & ~FD_CLOEXEC) != -1);
}
static void
service_register_core(void)
{
nvlist_t *nvl;
nvl = nvlist_create(0);
nvlist_add_string(nvl, "name", "core.casper");
nvlist_add_number(nvl, "limitfunc", (uint64_t)(uintptr_t)casper_limit);
nvlist_add_number(nvl, "commandfunc",
(uint64_t)(uintptr_t)casper_command);
service_register(nvl);
}
static int
setup_creds(int sock)
{
struct cmsgcred cred;
if (cred_recv(sock, &cred) == -1)
return (-1);
if (setgroups((int)cred.cmcred_ngroups, cred.cmcred_groups) == -1)
return (-1);
if (setgid(cred.cmcred_groups[0]) == -1)
return (-1);
if (setuid(cred.cmcred_euid) == -1)
return (-1);
return (0);
}
static void
service_external_execute(int chanfd)
{
char *service, *argv[3];
int stderrfd, execfd, procfd;
nvlist_t *nvl;
nvl = nvlist_recv(chanfd, 0);
if (nvl == NULL)
pjdlog_exit(1, "Unable to receive nvlist");
service = nvlist_take_string(nvl, "service");
PJDLOG_ASSERT(service != NULL);
if (nvlist_exists_descriptor(nvl, "stderrfd")) {
stderrfd = nvlist_take_descriptor(nvl, "stderrfd");
} else {
stderrfd = open(_PATH_DEVNULL, O_RDWR);
if (stderrfd < 0)
pjdlog_exit(1, "Unable to open %s", _PATH_DEVNULL);
}
execfd = nvlist_take_descriptor(nvl, "execfd");
procfd = nvlist_take_descriptor(nvl, "procfd");
nvlist_destroy(nvl);
/*
* Move all descriptors into right slots.
*/
if (stderrfd != STDERR_FILENO) {
if (chanfd == STDERR_FILENO)
fdswap(&stderrfd, &chanfd);
else if (execfd == STDERR_FILENO)
fdswap(&stderrfd, &execfd);
else if (procfd == STDERR_FILENO)
fdswap(&stderrfd, &procfd);
fdmove(&stderrfd, STDERR_FILENO);
}
fdcloexec(stderrfd);
if (chanfd != PARENT_FILENO) {
if (execfd == PARENT_FILENO)
fdswap(&chanfd, &execfd);
else if (procfd == PARENT_FILENO)
fdswap(&chanfd, &procfd);
fdmove(&chanfd, PARENT_FILENO);
}
fdcloexec(chanfd);
if (execfd != EXECUTABLE_FILENO) {
if (procfd == EXECUTABLE_FILENO)
fdswap(&execfd, &procfd);
fdmove(&execfd, EXECUTABLE_FILENO);
}
fdcloexec(execfd);
if (procfd != PROC_FILENO)
fdmove(&procfd, PROC_FILENO);
fdcloexec(procfd);
/*
* Use credentials of the caller process.
*/
setup_creds(chanfd);
argv[0] = service;
asprintf(&argv[1], "%d", pjdlog_debug_get());
argv[2] = NULL;
fexecve(execfd, argv, NULL);
pjdlog_exit(1, "Unable to execute service %s", service);
}
static void
service_register_external_one(const char *dirpath, int dfd,
const char *filename)
{
char execpath[FILENAME_MAX];
nvlist_t *nvl;
ssize_t done;
int fd;
fd = openat(dfd, filename, O_RDONLY);
if (fd == -1) {
pjdlog_errno(LOG_ERR, "Unable to open \"%s/%s\"", dirpath,
filename);
return;
}
done = read(fd, execpath, sizeof(execpath));
if (done == -1) {
pjdlog_errno(LOG_ERR, "Unable to read content of \"%s/%s\"",
dirpath, filename);
close(fd);
return;
}
close(fd);
if (done == sizeof(execpath)) {
pjdlog_error("Executable path too long in \"%s/%s\".", dirpath,
filename);
return;
}
execpath[done] = '\0';
while (done > 0) {
if (execpath[--done] == '\n')
execpath[done] = '\0';
}
nvl = nvlist_create(0);
nvlist_add_string(nvl, "name", filename);
nvlist_add_string(nvl, "execpath", execpath);
if (nvlist_error(nvl) != 0) {
pjdlog_common(LOG_ERR, 0, nvlist_error(nvl),
"Unable to allocate attributes for service \"%s/%s\"",
dirpath, filename);
nvlist_destroy(nvl);
return;
}
service_register(nvl);
/* service_register() consumed nvl. */
}
static uint8_t
file_type(int dfd, const char *filename)
{
struct stat sb;
if (fstatat(dfd, filename, &sb, AT_SYMLINK_NOFOLLOW) == -1) {
pjdlog_errno(LOG_ERR, "Unable to stat \"%s\"", filename);
return (DT_UNKNOWN);
}
return (IFTODT(sb.st_mode));
}
static void
service_register_external(const char *dirpath)
{
DIR *dirp;
struct dirent *dp;
int dfd;
dirp = opendir(dirpath);
if (dirp == NULL) {
pjdlog_errno(LOG_WARNING, "Unable to open \"%s\"", dirpath);
return;
}
dfd = dirfd(dirp);
PJDLOG_ASSERT(dfd >= 0);
while ((dp = readdir(dirp)) != NULL) {
dp->d_type = file_type(dfd, dp->d_name);
/* We are only interested in regular files, skip the rest. */
if (dp->d_type != DT_REG) {
pjdlog_debug(1,
"File \"%s/%s\" is not a regular file, skipping.",
dirpath, dp->d_name);
continue;
}
service_register_external_one(dirpath, dfd, dp->d_name);
}
closedir(dirp);
}
static void
casper_accept(int lsock)
{
struct casper_service *casserv;
struct service_connection *sconn;
int sock;
sock = accept(lsock, NULL, NULL);
if (sock == -1) {
pjdlog_errno(LOG_ERR, "Unable to accept casper connection");
return;
}
casserv = service_find("core.casper");
PJDLOG_ASSERT(casserv != NULL);
sconn = service_connection_add(casserv->cs_service, sock, NULL);
if (sconn == NULL) {
close(sock);
return;
}
}
static void
main_loop(int lqlen, const char *sockpath, struct pidfh *pfh)
{
fd_set fds;
struct sockaddr_un sun;
struct casper_service *casserv;
struct service_connection *sconn, *sconntmp;
int lsock, sock, maxfd, ret;
mode_t oldumask;
lsock = socket(AF_UNIX, SOCK_STREAM, 0);
if (lsock == -1)
pjdlog_exit(1, "Unable to create socket");
(void)unlink(sockpath);
bzero(&sun, sizeof(sun));
sun.sun_family = AF_UNIX;
PJDLOG_VERIFY(strlcpy(sun.sun_path, sockpath, sizeof(sun.sun_path)) <
sizeof(sun.sun_path));
sun.sun_len = SUN_LEN(&sun);
oldumask = umask(S_IXUSR | S_IXGRP | S_IXOTH);
if (bind(lsock, (struct sockaddr *)&sun, sizeof(sun)) == -1)
pjdlog_exit(1, "Unable to bind to %s", sockpath);
(void)umask(oldumask);
if (listen(lsock, lqlen) == -1)
pjdlog_exit(1, "Unable to listen on %s", sockpath);
for (;;) {
FD_ZERO(&fds);
FD_SET(lsock, &fds);
maxfd = lsock;
TAILQ_FOREACH(casserv, &casper_services, cs_next) {
/* We handle only core services. */
if (!SERVICE_IS_CORE(casserv))
continue;
for (sconn = service_connection_first(casserv->cs_service);
sconn != NULL;
sconn = service_connection_next(sconn)) {
sock = service_connection_get_sock(sconn);
FD_SET(sock, &fds);
maxfd = sock > maxfd ? sock : maxfd;
}
}
maxfd++;
PJDLOG_ASSERT(maxfd <= (int)FD_SETSIZE);
ret = select(maxfd, &fds, NULL, NULL, NULL);
PJDLOG_ASSERT(ret == -1 || ret > 0); /* select() cannot timeout */
if (ret == -1) {
if (errno == EINTR)
continue;
KEEP_ERRNO((void)pidfile_remove(pfh));
pjdlog_exit(1, "select() failed");
}
if (FD_ISSET(lsock, &fds))
casper_accept(lsock);
TAILQ_FOREACH(casserv, &casper_services, cs_next) {
/* We handle only core services. */
if (!SERVICE_IS_CORE(casserv))
continue;
for (sconn = service_connection_first(casserv->cs_service);
sconn != NULL; sconn = sconntmp) {
/*
* Prepare for connection to be removed from
* the list on failure.
*/
sconntmp = service_connection_next(sconn);
sock = service_connection_get_sock(sconn);
if (FD_ISSET(sock, &fds)) {
service_message(casserv->cs_service,
sconn);
}
}
}
}
}
static void
usage(void)
{
pjdlog_exitx(1,
"usage: casperd [-Fhv] [-D servconfdir] [-P pidfile] [-S sockpath]");
}
int
main(int argc, char *argv[])
{
struct pidfh *pfh;
const char *pidfile, *servconfdir, *sockpath;
pid_t otherpid;
int ch, debug, lqlen;
bool foreground;
pjdlog_init(PJDLOG_MODE_STD);
debug = 0;
foreground = false;
lqlen = SOMAXCONN;
pidfile = CASPERD_PIDFILE;
servconfdir = CASPERD_SERVCONFDIR;
sockpath = CASPERD_SOCKPATH;
while ((ch = getopt(argc, argv, "D:Fhl:P:S:v")) != -1) {
switch (ch) {
case 'D':
servconfdir = optarg;
break;
case 'F':
foreground = true;
break;
case 'l':
lqlen = strtol(optarg, NULL, 0);
if (lqlen < 1)
lqlen = SOMAXCONN;
break;
case 'P':
pidfile = optarg;
break;
case 'S':
sockpath = optarg;
break;
case 'v':
debug++;
break;
case 'h':
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc != 0)
usage();
if (!foreground)
pjdlog_mode_set(PJDLOG_MODE_SYSLOG);
pjdlog_prefix_set("(casperd) ");
pjdlog_debug_set(debug);
if (zygote_init() < 0)
pjdlog_exit(1, "Unable to create zygote process");
pfh = pidfile_open(pidfile, 0600, &otherpid);
if (pfh == NULL) {
if (errno == EEXIST) {
pjdlog_exitx(1, "casperd already running, pid: %jd.",
(intmax_t)otherpid);
}
pjdlog_errno(LOG_WARNING, "Cannot open or create pidfile %s",
pidfile);
}
if (!foreground) {
if (daemon(0, 0) == -1) {
KEEP_ERRNO((void)pidfile_remove(pfh));
pjdlog_exit(1, "Unable to go into background");
}
}
/* Write PID to a file. */
if (pidfile_write(pfh) == -1) {
pjdlog_errno(LOG_WARNING, "Unable to write to pidfile %s",
pidfile);
} else {
pjdlog_debug(1, "PID stored in %s.", pidfile);
}
/*
* Register core services.
*/
service_register_core();
/*
* Register external services.
*/
service_register_external(servconfdir);
/*
* Wait for connections.
*/
main_loop(lqlen, sockpath, pfh);
}
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