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freebsd/lib/libradius/radlib.c

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/*-
* Copyright 1998 Juniper Networks, Inc.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <md5.h>
#include <netdb.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "radlib_private.h"
static void clear_password(struct rad_handle *);
static void generr(struct rad_handle *, const char *, ...)
__printflike(2, 3);
static void insert_scrambled_password(struct rad_handle *, int);
static int is_valid_response(struct rad_handle *, int,
const struct sockaddr_in *);
static int put_password_attr(struct rad_handle *, int,
const void *, size_t);
static int put_raw_attr(struct rad_handle *, int,
const void *, size_t);
static int split(char *, char *[], int, char *, size_t);
static void
clear_password(struct rad_handle *h)
{
if (h->pass_len != 0) {
memset(h->pass, 0, h->pass_len);
h->pass_len = 0;
h->pass_pos = 0;
}
}
static void
generr(struct rad_handle *h, const char *format, ...)
{
va_list ap;
va_start(ap, format);
vsnprintf(h->errmsg, ERRSIZE, format, ap);
va_end(ap);
}
static void
insert_scrambled_password(struct rad_handle *h, int srv)
{
MD5_CTX ctx;
unsigned char md5[16];
const struct rad_server *srvp;
int padded_len;
int pos;
srvp = &h->servers[srv];
padded_len = h->pass_len == 0 ? 16 : (h->pass_len+15) & ~0xf;
memcpy(md5, &h->request[POS_AUTH], LEN_AUTH);
for (pos = 0; pos < padded_len; pos += 16) {
int i;
/* Calculate the new scrambler */
MD5Init(&ctx);
MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
MD5Update(&ctx, md5, 16);
MD5Final(md5, &ctx);
/*
* Mix in the current chunk of the password, and copy
* the result into the right place in the request. Also
* modify the scrambler in place, since we will use this
* in calculating the scrambler for next time.
*/
for (i = 0; i < 16; i++)
h->request[h->pass_pos + pos + i] =
md5[i] ^= h->pass[pos + i];
}
}
/*
* Return true if the current response is valid for a request to the
* specified server.
*/
static int
is_valid_response(struct rad_handle *h, int srv,
const struct sockaddr_in *from)
{
MD5_CTX ctx;
unsigned char md5[16];
const struct rad_server *srvp;
int len;
srvp = &h->servers[srv];
/* Check the source address */
if (from->sin_family != srvp->addr.sin_family ||
from->sin_addr.s_addr != srvp->addr.sin_addr.s_addr ||
from->sin_port != srvp->addr.sin_port)
return 0;
/* Check the message length */
if (h->resp_len < POS_ATTRS)
return 0;
len = h->response[POS_LENGTH] << 8 | h->response[POS_LENGTH+1];
if (len > h->resp_len)
return 0;
/* Check the response authenticator */
MD5Init(&ctx);
MD5Update(&ctx, &h->response[POS_CODE], POS_AUTH - POS_CODE);
MD5Update(&ctx, &h->request[POS_AUTH], LEN_AUTH);
MD5Update(&ctx, &h->response[POS_ATTRS], len - POS_ATTRS);
MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
MD5Final(md5, &ctx);
if (memcmp(&h->response[POS_AUTH], md5, sizeof md5) != 0)
return 0;
return 1;
}
static int
put_password_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
int padded_len;
int pad_len;
if (h->pass_pos != 0) {
generr(h, "Multiple User-Password attributes specified");
return -1;
}
if (len > PASSSIZE)
len = PASSSIZE;
padded_len = len == 0 ? 16 : (len+15) & ~0xf;
pad_len = padded_len - len;
/*
* Put in a place-holder attribute containing all zeros, and
* remember where it is so we can fill it in later.
*/
clear_password(h);
put_raw_attr(h, type, h->pass, padded_len);
h->pass_pos = h->req_len - padded_len;
/* Save the cleartext password, padded as necessary */
memcpy(h->pass, value, len);
h->pass_len = len;
memset(h->pass + len, 0, pad_len);
return 0;
}
static int
put_raw_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
if (len > 253) {
generr(h, "Attribute too long");
return -1;
}
if (h->req_len + 2 + len > MSGSIZE) {
generr(h, "Maximum message length exceeded");
return -1;
}
h->request[h->req_len++] = type;
h->request[h->req_len++] = len + 2;
memcpy(&h->request[h->req_len], value, len);
h->req_len += len;
return 0;
}
int
rad_add_server(struct rad_handle *h, const char *host, int port,
const char *secret, int timeout, int tries)
{
struct rad_server *srvp;
if (h->num_servers >= MAXSERVERS) {
generr(h, "Too many RADIUS servers specified");
return -1;
}
srvp = &h->servers[h->num_servers];
memset(&srvp->addr, 0, sizeof srvp->addr);
srvp->addr.sin_len = sizeof srvp->addr;
srvp->addr.sin_family = AF_INET;
if (!inet_aton(host, &srvp->addr.sin_addr)) {
struct hostent *hent;
if ((hent = gethostbyname(host)) == NULL) {
generr(h, "%s: host not found", host);
return -1;
}
memcpy(&srvp->addr.sin_addr, hent->h_addr,
sizeof srvp->addr.sin_addr);
}
if (port != 0)
srvp->addr.sin_port = htons(port);
else {
struct servent *sent;
srvp->addr.sin_port =
(sent = getservbyname("radius", "udp")) != NULL ?
sent->s_port : htons(RADIUS_PORT);
}
if ((srvp->secret = strdup(secret)) == NULL) {
generr(h, "Out of memory");
return -1;
}
srvp->timeout = timeout;
srvp->max_tries = tries;
srvp->num_tries = 0;
h->num_servers++;
return 0;
}
void
rad_close(struct rad_handle *h)
{
int srv;
if (h->fd != -1)
close(h->fd);
for (srv = 0; srv < h->num_servers; srv++) {
memset(h->servers[srv].secret, 0,
strlen(h->servers[srv].secret));
free(h->servers[srv].secret);
}
clear_password(h);
free(h);
}
int
rad_config(struct rad_handle *h, const char *path)
{
FILE *fp;
char buf[MAXCONFLINE];
int linenum;
int retval;
if (path == NULL)
path = PATH_RADIUS_CONF;
if ((fp = fopen(path, "r")) == NULL) {
generr(h, "Cannot open \"%s\": %s", path, strerror(errno));
return -1;
}
retval = 0;
linenum = 0;
while (fgets(buf, sizeof buf, fp) != NULL) {
int len;
char *fields[4];
int nfields;
char msg[ERRSIZE];
char *host;
char *port_str;
char *secret;
char *timeout_str;
char *maxtries_str;
char *end;
unsigned long timeout;
unsigned long maxtries;
int port;
linenum++;
len = strlen(buf);
/* We know len > 0, else fgets would have returned NULL. */
if (buf[len - 1] != '\n') {
if (len == sizeof buf - 1)
generr(h, "%s:%d: line too long", path,
linenum);
else
generr(h, "%s:%d: missing newline", path,
linenum);
retval = -1;
break;
}
buf[len - 1] = '\0';
/* Extract the fields from the line. */
nfields = split(buf, fields, 4, msg, sizeof msg);
if (nfields == -1) {
generr(h, "%s:%d: %s", path, linenum, msg);
retval = -1;
break;
}
if (nfields == 0)
continue;
if (nfields < 2) {
generr(h, "%s:%d: missing shared secret", path,
linenum);
retval = -1;
break;
}
host = fields[0];
secret = fields[1];
timeout_str = fields[2];
maxtries_str = fields[3];
/* Parse and validate the fields. */
host = strtok(host, ":");
port_str = strtok(NULL, ":");
if (port_str != NULL) {
port = strtoul(port_str, &end, 10);
if (*end != '\0') {
generr(h, "%s:%d: invalid port", path,
linenum);
retval = -1;
break;
}
} else
port = 0;
if (timeout_str != NULL) {
timeout = strtoul(timeout_str, &end, 10);
if (*end != '\0') {
generr(h, "%s:%d: invalid timeout", path,
linenum);
retval = -1;
break;
}
} else
timeout = TIMEOUT;
if (maxtries_str != NULL) {
maxtries = strtoul(maxtries_str, &end, 10);
if (*end != '\0') {
generr(h, "%s:%d: invalid maxtries", path,
linenum);
retval = -1;
break;
}
} else
maxtries = MAXTRIES;
if (rad_add_server(h, host, port, secret, timeout, maxtries) ==
-1) {
char msg[ERRSIZE];
strcpy(msg, h->errmsg);
generr(h, "%s:%d: %s", path, linenum, msg);
retval = -1;
break;
}
}
/* Clear out the buffer to wipe a possible copy of a shared secret */
memset(buf, 0, sizeof buf);
fclose(fp);
return retval;
}
int
rad_create_request(struct rad_handle *h, int code)
{
int i;
h->request[POS_CODE] = code;
h->request[POS_IDENT] = ++h->ident;
/* Create a random authenticator */
for (i = 0; i < LEN_AUTH; i += 2) {
long r;
r = random();
h->request[POS_AUTH+i] = r;
h->request[POS_AUTH+i+1] = r >> 8;
}
h->req_len = POS_ATTRS;
clear_password(h);
return 0;
}
struct in_addr
rad_cvt_addr(const void *data)
{
struct in_addr value;
memcpy(&value.s_addr, data, sizeof value.s_addr);
return value;
}
u_int32_t
rad_cvt_int(const void *data)
{
u_int32_t value;
memcpy(&value, data, sizeof value);
return ntohl(value);
}
char *
rad_cvt_string(const void *data, size_t len)
{
char *s;
s = malloc(len + 1);
if (s != NULL) {
memcpy(s, data, len);
s[len] = '\0';
}
return s;
}
/*
* Returns the attribute type. If none are left, returns 0. On failure,
* returns -1.
*/
int
rad_get_attr(struct rad_handle *h, const void **value, size_t *len)
{
int type;
if (h->resp_pos >= h->resp_len)
return 0;
if (h->resp_pos + 2 > h->resp_len) {
generr(h, "Malformed attribute in response");
return -1;
}
type = h->response[h->resp_pos++];
*len = h->response[h->resp_pos++] - 2;
if (h->resp_pos + *len > h->resp_len) {
generr(h, "Malformed attribute in response");
return -1;
}
*value = &h->response[h->resp_pos];
h->resp_pos += *len;
return type;
}
/*
* Create and initialize a rad_handle structure, and return it to the
* caller. Can fail only if the necessary memory cannot be allocated.
* In that case, it returns NULL.
*/
struct rad_handle *
rad_open(void)
{
struct rad_handle *h;
h = (struct rad_handle *)malloc(sizeof(struct rad_handle));
if (h != NULL) {
srandomdev();
h->fd = -1;
h->num_servers = 0;
h->ident = random();
h->errmsg[0] = '\0';
memset(h->pass, 0, sizeof h->pass);
h->pass_len = 0;
h->pass_pos = 0;
h->chap_pass = 0;
}
return h;
}
int
rad_put_addr(struct rad_handle *h, int type, struct in_addr addr)
{
return rad_put_attr(h, type, &addr.s_addr, sizeof addr.s_addr);
}
int
rad_put_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
int result;
if (type == RAD_USER_PASSWORD)
result = put_password_attr(h, type, value, len);
else {
result = put_raw_attr(h, type, value, len);
if (result == 0 && type == RAD_CHAP_PASSWORD)
h->chap_pass = 1;
}
return result;
}
int
rad_put_int(struct rad_handle *h, int type, u_int32_t value)
{
u_int32_t nvalue;
nvalue = htonl(value);
return rad_put_attr(h, type, &nvalue, sizeof nvalue);
}
int
rad_put_string(struct rad_handle *h, int type, const char *str)
{
return rad_put_attr(h, type, str, strlen(str));
}
/*
* Returns the response type code on success, or -1 on failure.
*/
int
rad_send_request(struct rad_handle *h)
{
int total_tries;
int try;
int srv;
int n;
int got_valid_response;
/* Make sure we have a socket to use */
if (h->fd == -1) {
struct sockaddr_in sin;
if ((h->fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
generr(h, "Cannot create socket: %s", strerror(errno));
return -1;
}
memset(&sin, 0, sizeof sin);
sin.sin_len = sizeof sin;
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons(0);
if (bind(h->fd, (const struct sockaddr *)&sin,
sizeof sin) == -1) {
generr(h, "bind: %s", strerror(errno));
close(h->fd);
h->fd = -1;
return -1;
}
}
/* Make sure the user gave us a password */
if (h->pass_pos == 0 && !h->chap_pass) {
generr(h, "No User or Chap Password attributes given");
return -1;
}
if (h->pass_pos != 0 && h->chap_pass) {
generr(h, "Both User and Chap Password attributes given");
return -1;
}
/* Fill in the length field in the message */
h->request[POS_LENGTH] = h->req_len >> 8;
h->request[POS_LENGTH+1] = h->req_len;
/*
* Count the total number of tries we will make, and zero the
* counter for each server.
*/
total_tries = 0;
for (srv = 0; srv < h->num_servers; srv++) {
total_tries += h->servers[srv].max_tries;
h->servers[srv].num_tries = 0;
}
if (total_tries == 0) {
generr(h, "No RADIUS servers specified");
return -1;
}
srv = 0;
got_valid_response = 0;
for (try = 0; try < total_tries; try++) {
struct timeval timelimit;
struct timeval tv;
/*
* Scan round-robin to the next server that has some
* tries left. There is guaranteed to be one, or we
* would have exited this loop by now.
*/
while (h->servers[srv].num_tries >=
h->servers[srv].max_tries)
if (++srv >= h->num_servers)
srv = 0;
/* Insert the scrambled password into the request */
if (h->pass_pos != 0)
insert_scrambled_password(h, srv);
/* Send the request */
n = sendto(h->fd, h->request, h->req_len, 0,
(const struct sockaddr *)&h->servers[srv].addr,
sizeof h->servers[srv].addr);
if (n != h->req_len) {
if (n == -1)
generr(h, "sendto: %s", strerror(errno));
else
generr(h, "sendto: short write");
return -1;
}
h->servers[srv].num_tries++;
/* Wait for a valid response */
gettimeofday(&timelimit, NULL);
timelimit.tv_sec += h->servers[srv].timeout;
tv.tv_sec = h->servers[srv].timeout;
tv.tv_usec = 0;
for ( ; ; ) {
fd_set readfds;
FD_ZERO(&readfds);
FD_SET(h->fd, &readfds);
n = select(h->fd + 1, &readfds, NULL, NULL, &tv);
if (n == -1) {
generr(h, "select: %s", strerror(errno));
return -1;
}
if (n == 0) /* Timed out */
break;
if (FD_ISSET(h->fd, &readfds)) {
struct sockaddr_in from;
int fromlen;
fromlen = sizeof from;
h->resp_len = recvfrom(h->fd, h->response,
MSGSIZE, MSG_WAITALL,
(struct sockaddr *)&from, &fromlen);
if (h->resp_len == -1) {
generr(h, "recvfrom: %s",
strerror(errno));
return -1;
}
if (is_valid_response(h, srv, &from)) {
got_valid_response = 1;
break;
}
}
/* Compute a new timeout */
gettimeofday(&tv, NULL);
timersub(&timelimit, &tv, &tv);
if (tv.tv_sec < 0) /* Still poll once more */
timerclear(&tv);
}
if (got_valid_response)
break;
/* Advance to the next server */
if (++srv >= h->num_servers)
srv = 0;
}
if (!got_valid_response) {
generr(h, "No valid RADIUS responses received");
return -1;
}
h->resp_len = h->response[POS_LENGTH] << 8 | h->response[POS_LENGTH+1];
h->resp_pos = POS_ATTRS;
return h->response[POS_CODE];
}
const char *
rad_strerror(struct rad_handle *h)
{
return h->errmsg;
}
/*
* Destructively split a string into fields separated by white space.
* `#' at the beginning of a field begins a comment that extends to the
* end of the string. Fields may be quoted with `"'. Inside quoted
* strings, the backslash escapes `\"' and `\\' are honored.
*
* Pointers to up to the first maxfields fields are stored in the fields
* array. Missing fields get NULL pointers.
*
* The return value is the actual number of fields parsed, and is always
* <= maxfields.
*
* On a syntax error, places a message in the msg string, and returns -1.
*/
static int
split(char *str, char *fields[], int maxfields, char *msg, size_t msglen)
{
char *p;
int i;
static const char ws[] = " \t";
for (i = 0; i < maxfields; i++)
fields[i] = NULL;
p = str;
i = 0;
while (*p != '\0') {
p += strspn(p, ws);
if (*p == '#' || *p == '\0')
break;
if (i >= maxfields) {
snprintf(msg, msglen, "line has too many fields");
return -1;
}
if (*p == '"') {
char *dst;
dst = ++p;
fields[i] = dst;
while (*p != '"') {
if (*p == '\\') {
p++;
if (*p != '"' && *p != '\\' &&
*p != '\0') {
snprintf(msg, msglen,
"invalid `\\' escape");
return -1;
}
}
if (*p == '\0') {
snprintf(msg, msglen,
"unterminated quoted string");
return -1;
}
*dst++ = *p++;
}
*dst = '\0';
p++;
if (*fields[i] == '\0') {
snprintf(msg, msglen,
"empty quoted string not permitted");
return -1;
}
if (*p != '\0' && strspn(p, ws) == 0) {
snprintf(msg, msglen, "quoted string not"
" followed by white space");
return -1;
}
} else {
fields[i] = p;
p += strcspn(p, ws);
if (*p != '\0')
*p++ = '\0';
}
i++;
}
return i;
}