heimdal/kcm/connect.c

/*
 * Copyright (c) 1997-2004 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * 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. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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 "kcm_locl.h"

RCSID("$Id$");

struct descr {
    int s;
    int type;
    char *path;
    unsigned char *buf;
    size_t size;
    size_t len;
    time_t timeout;
    struct sockaddr_storage __ss;
    struct sockaddr *sa;
    socklen_t sock_len;
    struct {
	uid_t uid;
	gid_t gid;
	pid_t pid;
    } peercred;
};

static void
init_descr(struct descr *d)
{
    memset(d, 0, sizeof(*d));
    d->sa = (struct sockaddr *)&d->__ss;
    d->s = -1;
}

/*
 * re-initialize all `n' ->sa in `d'.
 */

static void
reinit_descrs (struct descr *d, int n)
{
    int i;

    for (i = 0; i < n; ++i)
	d[i].sa = (struct sockaddr *)&d[i].__ss;
}

/*
 * Create the socket (family, type, port) in `d'
 */

static void 
init_socket(struct descr *d)
{
    struct sockaddr_un sun;
    struct sockaddr *sa = (struct sockaddr *)&sun;
    krb5_socklen_t sa_size = sizeof(sun);

    init_descr (d);

    sun.sun_family = AF_UNIX;

    if (socket_path != NULL)
	d->path = socket_path;
    else
	d->path = _PATH_KCM_SOCKET;

    strlcpy(sun.sun_path, d->path, sizeof(sun.sun_path));

    d->s = socket(AF_UNIX, SOCK_STREAM, 0);
    if (d->s < 0){
	krb5_warn(kcm_context, errno, "socket(%d, %d, 0)", AF_UNIX, SOCK_STREAM);
	d->s = -1;
	return;
    }
#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_REUSEADDR)
    {
	int one = 1;
	setsockopt(d->s, SOL_SOCKET, SO_REUSEADDR, (void *)&one, sizeof(one));
    }
#endif
#ifdef LOCAL_CREDS
    {
	int one = 1;
	setsockopt(d->s, 0, LOCAL_CREDS, (void *)&one, sizeof(one));
    }
#endif

    d->type = SOCK_STREAM;

    unlink(d->path);

    if (bind(d->s, sa, sa_size) < 0) {
	krb5_warn(kcm_context, errno, "bind %s", sun.sun_path);
	close(d->s);
	d->s = -1;
	return;
    }

    if (listen(d->s, SOMAXCONN) < 0) {
	krb5_warn(kcm_context, errno, "listen %s", sun.sun_path);
	close(d->s);
	d->s = -1;
	return;
    }

    chmod(d->path, 0777);

    return;
}

/*
 * Allocate descriptors for all the sockets that we should listen on
 * and return the number of them.
 */

static int
init_sockets(struct descr **desc)
{
    struct descr *d;
    size_t num = 0;

    d = (struct descr *)malloc(sizeof(*d));
    if (d == NULL) {
	krb5_errx(kcm_context, 1, "malloc failed");
    }

    init_socket(d);
    if (d->s != -1) {
	kcm_log(5, "listening on domain socket %s", d->path);
	num++;
    }

    reinit_descrs (d, num);
    *desc = d;

    return num;
}

/*
 * handle the request in `buf, len', from `addr' (or `from' as a string),
 * sending a reply in `reply'.
 */

static int
process_request(unsigned char *buf, 
		size_t len, 
		krb5_data *reply,
		kcm_client *client)
{
    krb5_data request;
   
    if (len < 4) {
	kcm_log(1, "malformed request from process %d (too short)", client->pid);
	return -1;
    }

    if (buf[0] != KCM_PROTOCOL_VERSION_MAJOR ||
	buf[1] != KCM_PROTOCOL_VERSION_MINOR) {
	kcm_log(1, "incorrect protocol version %d.%d from process %d",
		buf[0], buf[1], client->pid);
	return -1;
    }

    buf += 2;
    len -= 2;

    /* buf is now pointing at opcode */

    request.data = buf;
    request.length = len;

    return kcm_dispatch(kcm_context, client, &request, reply);
}

/*
 * Handle the request in `buf, len' to socket `d'
 */

static void
do_request(void *buf, size_t len, struct descr *d)
{
    krb5_error_code ret;
    krb5_data reply;
    kcm_client client;

    client.pid = d->peercred.pid;
    client.uid = d->peercred.uid;
    client.gid = d->peercred.gid;

    reply.length = 0;

    ret = process_request(buf, len, &reply, &client);
    if (reply.length != 0) {
	unsigned char len[4];

	kcm_log(5, "sending %lu bytes to process %d", (unsigned long)reply.length,
		client.pid);

	len[0] = (reply.length >> 24) & 0xff;
	len[1] = (reply.length >> 16) & 0xff;
	len[2] = (reply.length >> 8) & 0xff;
	len[3] = reply.length & 0xff;

	if (sendto(d->s, len, sizeof(len), 0, NULL, 0) < 0) {
	    kcm_log (0, "sendto(%d): %d %s", d->peercred.pid, strerror(errno));
	    krb5_data_free(&reply);
	    return;
	}
	if (sendto(d->s, reply.data, reply.length, 0, NULL, 0) < 0) {
	    kcm_log (0, "sendto(%d): %s", d->peercred.pid, strerror(errno));
	    krb5_data_free(&reply);
	    return;
	}

	krb5_data_free(&reply);
    }

    if (ret) {
	kcm_log(0, "Failed processing %lu byte request from process %d", 
		(unsigned long)len, d->peercred.pid);
    }
}

static void
clear_descr(struct descr *d)
{
    if(d->buf)
	memset(d->buf, 0, d->size);
    d->len = 0;
    if(d->s != -1)
	close(d->s);
    d->s = -1;
}

#define STREAM_TIMEOUT 4

/*
 * accept a new stream connection on `d[parent]' and store it in `d[child]'
 */

static void
add_new_stream (struct descr *d, int parent, int child)
{
    int s;

    if (child == -1)
	return;

    d[child].sock_len = sizeof(d[child].__ss);
    s = accept(d[parent].s, d[child].sa, &d[child].sock_len);
    if(s < 0) {
	krb5_warn(kcm_context, errno, "accept");
	return;
    }

    if (s >= FD_SETSIZE) {
	krb5_warnx(kcm_context, "socket FD too large");
	close (s);
	return;
    }

    d[child].s = s;
    d[child].timeout = time(NULL) + STREAM_TIMEOUT;
    d[child].type = SOCK_STREAM;
}

/*
 * Grow `d' to handle at least `n'.
 * Return != 0 if fails
 */

static int
grow_descr (struct descr *d, size_t n)
{
    if (d->size - d->len < n) {
	unsigned char *tmp;
	size_t grow;

	grow = max(1024, d->len + n);
	if (d->size + grow > max_request) {
	    kcm_log(0, "Request exceeds max request size (%lu bytes).",
		    (unsigned long)d->size + grow);
	    clear_descr(d);
	    return -1;
	}
	tmp = realloc (d->buf, d->size + grow);
	if (tmp == NULL) {
	    kcm_log(0, "Failed to re-allocate %lu bytes.",
		    (unsigned long)d->size + grow);
	    clear_descr(d);
	    return -1;
	}
	d->size += grow;
	d->buf = tmp;
    }
    return 0;
}

/*
 * Handle incoming data to the stream socket in `d[index]'
 */

static void
handle_stream(struct descr *d, int index, int min_free)
{
    unsigned char buf[1024];
    int n;
    int ret = 0;

    if (d[index].timeout == 0) {
	add_new_stream (d, index, min_free);
	return;
    }

    d[index].peercred.pid = 0;
    d[index].peercred.uid = -1;
    d[index].peercred.gid = -1;

#ifdef SO_PEERCRED
    {
	socklen_t pclen;
	struct ucred pc;

	if (getsockopt(d[index].s, SOL_SOCKET, SO_PEERCRED, (void *)&pc,
		       &pclen) != 0) {
	    krb5_warn(kcm_context, errno, "failed to determine peer identity");
	    return;
	}
	d[index].peercred.uid = pc.uid;
	d[index].peercred.gid = pc.gid;
	d[index].peercred.pid = pc.pid;
    }
#else
    krb5_warnx(kcm_context, "code unimplemented to get peer identity");
    return;
#endif

    n = recvfrom(d[index].s, buf, sizeof(buf), 0, NULL, NULL);
    if (n < 0) {
	krb5_warn(kcm_context, errno, "recvfrom");
	return;
    } else if (n == 0) {
	krb5_warnx(kcm_context, "connection closed before end of data after %lu "
		   "bytes from process %d",
		   (unsigned long)d[index].len, d[index].peercred.pid);
	clear_descr (d + index);
	return;
    }
    if (grow_descr (&d[index], n))
	return;
    memcpy(d[index].buf + d[index].len, buf, n);
    d[index].len += n;
    if (d[index].len > 4) {
	krb5_storage *sp;
	int32_t len;

	sp = krb5_storage_from_mem(d[index].buf, d[index].len);
	if (sp == NULL) {
	    kcm_log (0, "krb5_storage_from_mem failed");
	    ret = -1;
	} else {
	    krb5_ret_int32(sp, &len);
	    krb5_storage_free(sp);
	    if (d[index].len - 4 >= len) {
		memmove(d[index].buf, d[index].buf + 4, d[index].len - 4);
		ret = 1;
	    } else
		ret = 0;
	}
    }
    if (ret < 0)
	return;
    else if (ret == 1) {
	do_request(d[index].buf, d[index].len, &d[index]);
	clear_descr(d + index);
    }
}

void
kcm_loop(void)
{
    struct descr *d;
    int ndescr;

    ndescr = init_sockets(&d);
    if (ndescr <= 0)
	krb5_errx(kcm_context, 1, "No sockets!");
    while (exit_flag == 0){
	struct timeval tmout;
	fd_set fds;
	int min_free = -1;
	int max_fd = 0;
	int i;

	FD_ZERO(&fds);
	for(i = 0; i < ndescr; i++) {
	    if (d[i].s >= 0){
		if(d[i].type == SOCK_STREAM && 
		   d[i].timeout && d[i].timeout < time(NULL)) {
		    kcm_log(1, "Stream connection from %d expired after %lu bytes",
			    d[i].peercred.pid, (unsigned long)d[i].len);
		    clear_descr(&d[i]);
		    continue;
		}
		if (max_fd < d[i].s)
		    max_fd = d[i].s;
		if (max_fd >= FD_SETSIZE)
		    krb5_errx(kcm_context, 1, "fd too large");
		FD_SET(d[i].s, &fds);
	    } else if (min_free < 0 || i < min_free)
		min_free = i;
	}
	if (min_free == -1) {
	    struct descr *tmp;
	    tmp = realloc(d, (ndescr + 4) * sizeof(*d));
	    if(tmp == NULL)
		krb5_warnx(kcm_context, "No memory");
	    else {
		d = tmp;
		reinit_descrs (d, ndescr);
		memset(d + ndescr, 0, 4 * sizeof(*d));
		for(i = ndescr; i < ndescr + 4; i++)
		    init_descr (&d[i]);
		min_free = ndescr;
		ndescr += 4;
	    }
	}

	tmout.tv_sec = STREAM_TIMEOUT;
	tmout.tv_usec = 0;
	switch (select(max_fd + 1, &fds, 0, 0, &tmout)){
	case 0:
	    kcm_run_events(kcm_context, time(NULL));
	    break;
	case -1:
	    if (errno != EINTR)
		krb5_warn(kcm_context, errno, "select");
	    break;
	default:
	    for(i = 0; i < ndescr; i++) {
		if(d[i].s >= 0 && FD_ISSET(d[i].s, &fds)) {
		    if (d[i].type == SOCK_STREAM)
			handle_stream(d, i, min_free);
		}
	    }
	    kcm_run_events(kcm_context, time(NULL));
	}
    }
    if (d->path != NULL)
	unlink(d->path);
    free(d);
}