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/* $NetBSD: bl.c,v 1.27 2015/12/30 16:42:48 christos Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christos Zoulas.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/cdefs.h>
__RCSID("$NetBSD: bl.c,v 1.27 2015/12/30 16:42:48 christos Exp $");
#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <signal.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <stdbool.h>
#include <errno.h>
#include <stdarg.h>
#include <netinet/in.h>
#ifdef _REENTRANT
#include <pthread.h>
#endif
#include "bl.h"
typedef struct {
uint32_t bl_len;
uint32_t bl_version;
uint32_t bl_type;
uint32_t bl_salen;
struct sockaddr_storage bl_ss;
char bl_data[];
} bl_message_t;
struct blacklist {
#ifdef _REENTRANT
pthread_mutex_t b_mutex;
# define BL_INIT(b) pthread_mutex_init(&b->b_mutex, NULL)
# define BL_LOCK(b) pthread_mutex_lock(&b->b_mutex)
# define BL_UNLOCK(b) pthread_mutex_unlock(&b->b_mutex)
#else
# define BL_INIT(b) do {} while(/*CONSTCOND*/0)
# define BL_LOCK(b) BL_INIT(b)
# define BL_UNLOCK(b) BL_INIT(b)
#endif
int b_fd;
int b_connected;
struct sockaddr_un b_sun;
void (*b_fun)(int, const char *, va_list);
bl_info_t b_info;
};
#define BL_VERSION 1
bool
bl_isconnected(bl_t b)
{
return b->b_connected == 0;
}
int
bl_getfd(bl_t b)
{
return b->b_fd;
}
static void
bl_reset(bl_t b, bool locked)
{
int serrno = errno;
if (!locked)
BL_LOCK(b);
close(b->b_fd);
errno = serrno;
b->b_fd = -1;
b->b_connected = -1;
if (!locked)
BL_UNLOCK(b);
}
static void
bl_log(void (*fun)(int, const char *, va_list), int level,
const char *fmt, ...)
{
va_list ap;
int serrno = errno;
va_start(ap, fmt);
(*fun)(level, fmt, ap);
va_end(ap);
errno = serrno;
}
static int
bl_init(bl_t b, bool srv)
{
static int one = 1;
/* AF_UNIX address of local logger */
mode_t om;
int rv, serrno;
struct sockaddr_un *sun = &b->b_sun;
#ifndef SOCK_NONBLOCK
#define SOCK_NONBLOCK 0
#endif
#ifndef SOCK_CLOEXEC
#define SOCK_CLOEXEC 0
#endif
#ifndef SOCK_NOSIGPIPE
#define SOCK_NOSIGPIPE 0
#endif
BL_LOCK(b);
if (b->b_fd == -1) {
b->b_fd = socket(PF_LOCAL,
SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK|SOCK_NOSIGPIPE, 0);
if (b->b_fd == -1) {
bl_log(b->b_fun, LOG_ERR, "%s: socket failed (%m)",
__func__);
BL_UNLOCK(b);
return -1;
}
#if SOCK_CLOEXEC == 0
fcntl(b->b_fd, F_SETFD, FD_CLOEXEC);
#endif
#if SOCK_NONBLOCK == 0
fcntl(b->b_fd, F_SETFL, fcntl(b->b_fd, F_GETFL) | O_NONBLOCK);
#endif
#if SOCK_NOSIGPIPE == 0
#ifdef SO_NOSIGPIPE
int o = 1;
setsockopt(b->b_fd, SOL_SOCKET, SO_NOSIGPIPE, &o, sizeof(o));
#else
signal(SIGPIPE, SIG_IGN);
#endif
#endif
}
if (bl_isconnected(b)) {
BL_UNLOCK(b);
return 0;
}
/*
* We try to connect anyway even when we are a server to verify
* that no other server is listening to the socket. If we succeed
* to connect and we are a server, someone else owns it.
*/
rv = connect(b->b_fd, (const void *)sun, (socklen_t)sizeof(*sun));
if (rv == 0) {
if (srv) {
bl_log(b->b_fun, LOG_ERR,
"%s: another daemon is handling `%s'",
__func__, sun->sun_path);
goto out;
}
} else {
if (!srv) {
/*
* If the daemon is not running, we just try a
* connect, so leave the socket alone until it does
* and only log once.
*/
if (b->b_connected != 1) {
bl_log(b->b_fun, LOG_DEBUG,
"%s: connect failed for `%s' (%m)",
__func__, sun->sun_path);
b->b_connected = 1;
}
BL_UNLOCK(b);
return -1;
}
bl_log(b->b_fun, LOG_DEBUG, "Connected to blacklist server",
__func__);
}
if (srv) {
(void)unlink(sun->sun_path);
om = umask(0);
rv = bind(b->b_fd, (const void *)sun, (socklen_t)sizeof(*sun));
serrno = errno;
(void)umask(om);
errno = serrno;
if (rv == -1) {
bl_log(b->b_fun, LOG_ERR,
"%s: bind failed for `%s' (%m)",
__func__, sun->sun_path);
goto out;
}
}
b->b_connected = 0;
#define GOT_FD 1
#if defined(LOCAL_CREDS)
#define CRED_LEVEL 0
#define CRED_NAME LOCAL_CREDS
#define CRED_SC_UID sc_euid
#define CRED_SC_GID sc_egid
#define CRED_MESSAGE SCM_CREDS
#define CRED_SIZE SOCKCREDSIZE(NGROUPS_MAX)
#define CRED_TYPE struct sockcred
#define GOT_CRED 2
#elif defined(SO_PASSCRED)
#define CRED_LEVEL SOL_SOCKET
#define CRED_NAME SO_PASSCRED
#define CRED_SC_UID uid
#define CRED_SC_GID gid
#define CRED_MESSAGE SCM_CREDENTIALS
#define CRED_SIZE sizeof(struct ucred)
#define CRED_TYPE struct ucred
#define GOT_CRED 2
#else
#define GOT_CRED 0
/*
* getpeereid() and LOCAL_PEERCRED don't help here
* because we are not a stream socket!
*/
#define CRED_SIZE 0
#define CRED_TYPE void * __unused
#endif
#ifdef CRED_LEVEL
if (setsockopt(b->b_fd, CRED_LEVEL, CRED_NAME,
&one, (socklen_t)sizeof(one)) == -1) {
bl_log(b->b_fun, LOG_ERR, "%s: setsockopt %s "
"failed (%m)", __func__, __STRING(CRED_NAME));
goto out;
}
#endif
BL_UNLOCK(b);
return 0;
out:
bl_reset(b, true);
BL_UNLOCK(b);
return -1;
}
bl_t
bl_create(bool srv, const char *path, void (*fun)(int, const char *, va_list))
{
bl_t b = calloc(1, sizeof(*b));
if (b == NULL)
goto out;
b->b_fun = fun == NULL ? vsyslog : fun;
b->b_fd = -1;
b->b_connected = -1;
BL_INIT(b);
memset(&b->b_sun, 0, sizeof(b->b_sun));
b->b_sun.sun_family = AF_LOCAL;
#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
b->b_sun.sun_len = sizeof(b->b_sun);
#endif
strlcpy(b->b_sun.sun_path,
path ? path : _PATH_BLSOCK, sizeof(b->b_sun.sun_path));
bl_init(b, srv);
return b;
out:
free(b);
bl_log(fun, LOG_ERR, "%s: malloc failed (%m)", __func__);
return NULL;
}
void
bl_destroy(bl_t b)
{
bl_reset(b, false);
free(b);
}
static int
bl_getsock(bl_t b, struct sockaddr_storage *ss, const struct sockaddr *sa,
socklen_t slen, const char *ctx)
{
uint8_t family;
memset(ss, 0, sizeof(*ss));
switch (slen) {
case 0:
return 0;
case sizeof(struct sockaddr_in):
family = AF_INET;
break;
case sizeof(struct sockaddr_in6):
family = AF_INET6;
break;
default:
bl_log(b->b_fun, LOG_ERR, "%s: invalid socket len %u (%s)",
__func__, (unsigned)slen, ctx);
errno = EINVAL;
return -1;
}
memcpy(ss, sa, slen);
if (ss->ss_family != family) {
bl_log(b->b_fun, LOG_INFO,
"%s: correcting socket family %d to %d (%s)",
__func__, ss->ss_family, family, ctx);
ss->ss_family = family;
}
#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
if (ss->ss_len != slen) {
bl_log(b->b_fun, LOG_INFO,
"%s: correcting socket len %u to %u (%s)",
__func__, ss->ss_len, (unsigned)slen, ctx);
ss->ss_len = (uint8_t)slen;
}
#endif
return 0;
}
int
bl_send(bl_t b, bl_type_t e, int pfd, const struct sockaddr *sa,
socklen_t slen, const char *ctx)
{
struct msghdr msg;
struct iovec iov;
union {
char ctrl[CMSG_SPACE(sizeof(int))];
uint32_t fd;
} ua;
struct cmsghdr *cmsg;
union {
bl_message_t bl;
char buf[512];
} ub;
size_t ctxlen, tried;
#define NTRIES 5
ctxlen = strlen(ctx);
if (ctxlen > 128)
ctxlen = 128;
iov.iov_base = ub.buf;
iov.iov_len = sizeof(bl_message_t) + ctxlen;
ub.bl.bl_len = (uint32_t)iov.iov_len;
ub.bl.bl_version = BL_VERSION;
ub.bl.bl_type = (uint32_t)e;
if (bl_getsock(b, &ub.bl.bl_ss, sa, slen, ctx) == -1)
return -1;
ub.bl.bl_salen = slen;
memcpy(ub.bl.bl_data, ctx, ctxlen);
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_flags = 0;
msg.msg_control = ua.ctrl;
msg.msg_controllen = sizeof(ua.ctrl);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
memcpy(CMSG_DATA(cmsg), &pfd, sizeof(pfd));
tried = 0;
again:
if (bl_init(b, false) == -1)
return -1;
if ((sendmsg(b->b_fd, &msg, 0) == -1) && tried++ < NTRIES) {
bl_reset(b, false);
goto again;
}
return tried >= NTRIES ? -1 : 0;
}
bl_info_t *
bl_recv(bl_t b)
{
struct msghdr msg;
struct iovec iov;
union {
char ctrl[CMSG_SPACE(sizeof(int)) + CMSG_SPACE(CRED_SIZE)];
uint32_t fd;
CRED_TYPE sc;
} ua;
struct cmsghdr *cmsg;
CRED_TYPE *sc;
union {
bl_message_t bl;
char buf[512];
} ub;
int got;
ssize_t rlen;
bl_info_t *bi = &b->b_info;
got = 0;
memset(bi, 0, sizeof(*bi));
iov.iov_base = ub.buf;
iov.iov_len = sizeof(ub);
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_flags = 0;
msg.msg_control = ua.ctrl;
msg.msg_controllen = sizeof(ua.ctrl) + 100;
rlen = recvmsg(b->b_fd, &msg, 0);
if (rlen == -1) {
bl_log(b->b_fun, LOG_ERR, "%s: recvmsg failed (%m)", __func__);
return NULL;
}
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level != SOL_SOCKET) {
bl_log(b->b_fun, LOG_ERR,
"%s: unexpected cmsg_level %d",
__func__, cmsg->cmsg_level);
continue;
}
switch (cmsg->cmsg_type) {
case SCM_RIGHTS:
if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
bl_log(b->b_fun, LOG_ERR,
"%s: unexpected cmsg_len %d != %zu",
__func__, cmsg->cmsg_len,
CMSG_LEN(2 * sizeof(int)));
continue;
}
memcpy(&bi->bi_fd, CMSG_DATA(cmsg), sizeof(bi->bi_fd));
got |= GOT_FD;
break;
#ifdef CRED_MESSAGE
case CRED_MESSAGE:
sc = (void *)CMSG_DATA(cmsg);
bi->bi_uid = sc->CRED_SC_UID;
bi->bi_gid = sc->CRED_SC_GID;
got |= GOT_CRED;
break;
#endif
default:
bl_log(b->b_fun, LOG_ERR,
"%s: unexpected cmsg_type %d",
__func__, cmsg->cmsg_type);
continue;
}
}
if (got != (GOT_CRED|GOT_FD)) {
bl_log(b->b_fun, LOG_ERR, "message missing %s %s",
#if GOT_CRED != 0
(got & GOT_CRED) == 0 ? "cred" :
#endif
"", (got & GOT_FD) == 0 ? "fd" : "");
return NULL;
}
if ((size_t)rlen <= sizeof(ub.bl)) {
bl_log(b->b_fun, LOG_ERR, "message too short %zd", rlen);
return NULL;
}
if (ub.bl.bl_version != BL_VERSION) {
bl_log(b->b_fun, LOG_ERR, "bad version %d", ub.bl.bl_version);
return NULL;
}
bi->bi_type = ub.bl.bl_type;
bi->bi_slen = ub.bl.bl_salen;
bi->bi_ss = ub.bl.bl_ss;
#ifndef CRED_MESSAGE
bi->bi_uid = -1;
bi->bi_gid = -1;
#endif
strlcpy(bi->bi_msg, ub.bl.bl_data, MIN(sizeof(bi->bi_msg),
((size_t)rlen - sizeof(ub.bl) + 1)));
return bi;
}