FreeBSD-5.3/usr.sbin/inetd/builtins.c
/*-
* Copyright (c) 1983, 1991, 1993, 1994
* The Regents of the University of California. 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/usr.sbin/inetd/builtins.c,v 1.43 2002/07/22 13:58:58 fanf Exp $");
#include <sys/filio.h>
#include <sys/ioccom.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/ucred.h>
#include <sys/uio.h>
#include <sys/utsname.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <syslog.h>
#include <unistd.h>
#include "inetd.h"
void chargen_dg(int, struct servtab *);
void chargen_stream(int, struct servtab *);
void daytime_dg(int, struct servtab *);
void daytime_stream(int, struct servtab *);
void discard_dg(int, struct servtab *);
void discard_stream(int, struct servtab *);
void echo_dg(int, struct servtab *);
void echo_stream(int, struct servtab *);
static int getline(int, char *, int);
void iderror(int, int, int, const char *);
void ident_stream(int, struct servtab *);
void initring(void);
unsigned long machtime(void);
void machtime_dg(int, struct servtab *);
void machtime_stream(int, struct servtab *);
char ring[128];
char *endring;
struct biltin biltins[] = {
/* Echo received data */
{ "echo", SOCK_STREAM, 1, -1, echo_stream },
{ "echo", SOCK_DGRAM, 0, 1, echo_dg },
/* Internet /dev/null */
{ "discard", SOCK_STREAM, 1, -1, discard_stream },
{ "discard", SOCK_DGRAM, 0, 1, discard_dg },
/* Return 32 bit time since 1900 */
{ "time", SOCK_STREAM, 0, -1, machtime_stream },
{ "time", SOCK_DGRAM, 0, 1, machtime_dg },
/* Return human-readable time */
{ "daytime", SOCK_STREAM, 0, -1, daytime_stream },
{ "daytime", SOCK_DGRAM, 0, 1, daytime_dg },
/* Familiar character generator */
{ "chargen", SOCK_STREAM, 1, -1, chargen_stream },
{ "chargen", SOCK_DGRAM, 0, 1, chargen_dg },
{ "tcpmux", SOCK_STREAM, 1, -1, (bi_fn_t *)tcpmux },
{ "auth", SOCK_STREAM, 1, -1, ident_stream },
{ NULL, 0, 0, 0, NULL }
};
/*
* RFC864 Character Generator Protocol. Generates character data without
* any regard for input.
*/
void
initring(void)
{
int i;
endring = ring;
for (i = 0; i <= 128; ++i)
if (isprint(i))
*endring++ = i;
}
/* Character generator */
/* ARGSUSED */
void
chargen_dg(int s, struct servtab *sep)
{
struct sockaddr_storage ss;
static char *rs;
int len;
socklen_t size;
char text[LINESIZ+2];
if (endring == 0) {
initring();
rs = ring;
}
size = sizeof(ss);
if (recvfrom(s, text, sizeof(text), 0,
(struct sockaddr *)&ss, &size) < 0)
return;
if (check_loop((struct sockaddr *)&ss, sep))
return;
if ((len = endring - rs) >= LINESIZ)
memmove(text, rs, LINESIZ);
else {
memmove(text, rs, len);
memmove(text + len, ring, LINESIZ - len);
}
if (++rs == endring)
rs = ring;
text[LINESIZ] = '\r';
text[LINESIZ + 1] = '\n';
(void) sendto(s, text, sizeof(text), 0, (struct sockaddr *)&ss, size);
}
/* Character generator */
/* ARGSUSED */
void
chargen_stream(int s, struct servtab *sep)
{
int len;
char *rs, text[LINESIZ+2];
inetd_setproctitle(sep->se_service, s);
if (!endring) {
initring();
rs = ring;
}
text[LINESIZ] = '\r';
text[LINESIZ + 1] = '\n';
for (rs = ring;;) {
if ((len = endring - rs) >= LINESIZ)
memmove(text, rs, LINESIZ);
else {
memmove(text, rs, len);
memmove(text + len, ring, LINESIZ - len);
}
if (++rs == endring)
rs = ring;
if (write(s, text, sizeof(text)) != sizeof(text))
break;
}
exit(0);
}
/*
* RFC867 Daytime Protocol. Sends the current date and time as an ascii
* character string without any regard for input.
*/
/* Return human-readable time of day */
/* ARGSUSED */
void
daytime_dg(int s, struct servtab *sep)
{
char buffer[256];
time_t now;
struct sockaddr_storage ss;
socklen_t size;
now = time((time_t *) 0);
size = sizeof(ss);
if (recvfrom(s, buffer, sizeof(buffer), 0,
(struct sockaddr *)&ss, &size) < 0)
return;
if (check_loop((struct sockaddr *)&ss, sep))
return;
(void) sprintf(buffer, "%.24s\r\n", ctime(&now));
(void) sendto(s, buffer, strlen(buffer), 0,
(struct sockaddr *)&ss, size);
}
/* Return human-readable time of day */
/* ARGSUSED */
void
daytime_stream(int s, struct servtab *sep __unused)
{
char buffer[256];
time_t now;
now = time((time_t *) 0);
(void) sprintf(buffer, "%.24s\r\n", ctime(&now));
(void) send(s, buffer, strlen(buffer), MSG_EOF);
}
/*
* RFC863 Discard Protocol. Any data received is thrown away and no response
* is sent.
*/
/* Discard service -- ignore data */
/* ARGSUSED */
void
discard_dg(int s, struct servtab *sep __unused)
{
char buffer[BUFSIZE];
(void) read(s, buffer, sizeof(buffer));
}
/* Discard service -- ignore data */
/* ARGSUSED */
void
discard_stream(int s, struct servtab *sep)
{
int ret;
char buffer[BUFSIZE];
inetd_setproctitle(sep->se_service, s);
while (1) {
while ((ret = read(s, buffer, sizeof(buffer))) > 0)
;
if (ret == 0 || errno != EINTR)
break;
}
exit(0);
}
/*
* RFC862 Echo Protocol. Any data received is sent back to the sender as
* received.
*/
/* Echo service -- echo data back */
/* ARGSUSED */
void
echo_dg(int s, struct servtab *sep)
{
char buffer[65536]; /* Should be sizeof(max datagram). */
int i;
socklen_t size;
struct sockaddr_storage ss;
size = sizeof(ss);
if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
(struct sockaddr *)&ss, &size)) < 0)
return;
if (check_loop((struct sockaddr *)&ss, sep))
return;
(void) sendto(s, buffer, i, 0, (struct sockaddr *)&ss, size);
}
/* Echo service -- echo data back */
/* ARGSUSED */
void
echo_stream(int s, struct servtab *sep)
{
char buffer[BUFSIZE];
int i;
inetd_setproctitle(sep->se_service, s);
while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
write(s, buffer, i) > 0)
;
exit(0);
}
/*
* RFC1413 Identification Protocol. Given a TCP port number pair, return a
* character string which identifies the owner of that connection on the
* server's system. Extended to allow for ~/.fakeid support and ~/.noident
* support.
*/
/* RFC 1413 says the following are the only errors you can return. */
#define ID_INVALID "INVALID-PORT" /* Port number improperly specified. */
#define ID_NOUSER "NO-USER" /* Port not in use/not identifable. */
#define ID_HIDDEN "HIDDEN-USER" /* Hiden at user's request. */
#define ID_UNKNOWN "UNKNOWN-ERROR" /* Everything else. */
/* Generic ident_stream error-sending func */
/* ARGSUSED */
void
iderror(int lport, int fport, int s, const char *er)
{
char *p;
asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport, er);
if (p == NULL) {
syslog(LOG_ERR, "asprintf: %m");
exit(EX_OSERR);
}
send(s, p, strlen(p), MSG_EOF);
free(p);
exit(0);
}
/* Ident service (AKA "auth") */
/* ARGSUSED */
void
ident_stream(int s, struct servtab *sep)
{
struct utsname un;
struct stat sb;
struct sockaddr_in sin4[2];
#ifdef INET6
struct sockaddr_in6 sin6[2];
#endif
struct sockaddr_storage ss[2];
struct xucred uc;
struct timeval tv = {
10,
0
}, to;
struct passwd *pw = NULL;
fd_set fdset;
char buf[BUFSIZE], *p, **av, *osname = NULL, e;
char idbuf[MAXLOGNAME] = ""; /* Big enough to hold uid in decimal. */
socklen_t socklen;
ssize_t ssize;
size_t size, bufsiz;
int c, fflag = 0, nflag = 0, rflag = 0, argc = 0;
int gflag = 0, iflag = 0, Fflag = 0, getcredfail = 0, onreadlen;
u_short lport, fport;
inetd_setproctitle(sep->se_service, s);
/*
* Reset getopt() since we are a fork() but not an exec() from
* a parent which used getopt() already.
*/
optind = 1;
optreset = 1;
/*
* Take the internal argument vector and count it out to make an
* argument count for getopt. This can be used for any internal
* service to read arguments and use getopt() easily.
*/
for (av = sep->se_argv; *av; av++)
argc++;
if (argc) {
int sec, usec;
size_t i;
u_int32_t rnd32;
while ((c = getopt(argc, sep->se_argv, "d:fFgino:rt:")) != -1)
switch (c) {
case 'd':
if (!gflag)
strlcpy(idbuf, optarg, sizeof(idbuf));
break;
case 'f':
fflag = 1;
break;
case 'F':
fflag = 1;
Fflag=1;
break;
case 'g':
gflag = 1;
rnd32 = 0; /* Shush, compiler. */
/*
* The number of bits in "rnd32" divided
* by the number of bits needed per iteration
* gives a more optimal way to reload the
* random number only when necessary.
*
* 32 bits from arc4random corresponds to
* about 6 base-36 digits, so we reseed evey 6.
*/
for (i = 0; i < sizeof(idbuf) - 1; i++) {
static const char *const base36 =
"0123456789"
"abcdefghijklmnopqrstuvwxyz";
if (i % 6 == 0)
rnd32 = arc4random();
idbuf[i] = base36[rnd32 % 36];
rnd32 /= 36;
}
idbuf[i] = '\0';
break;
case 'i':
iflag = 1;
break;
case 'n':
nflag = 1;
break;
case 'o':
osname = optarg;
break;
case 'r':
rflag = 1;
break;
case 't':
switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
case 2:
tv.tv_usec = usec;
/* FALLTHROUGH */
case 1:
tv.tv_sec = sec;
break;
default:
if (debug)
warnx("bad -t argument");
break;
}
break;
default:
break;
}
}
if (osname == NULL) {
if (uname(&un) == -1)
iderror(0, 0, s, ID_UNKNOWN);
osname = un.sysname;
}
/*
* We're going to prepare for and execute reception of a
* packet of data from the user. The data is in the format
* "local_port , foreign_port\r\n" (with local being the
* server's port and foreign being the client's.)
*/
gettimeofday(&to, NULL);
to.tv_sec += tv.tv_sec;
to.tv_usec += tv.tv_usec;
if (to.tv_usec >= 1000000) {
to.tv_usec -= 1000000;
to.tv_sec++;
}
size = 0;
bufsiz = sizeof(buf) - 1;
FD_ZERO(&fdset);
while (bufsiz > 0) {
gettimeofday(&tv, NULL);
tv.tv_sec = to.tv_sec - tv.tv_sec;
tv.tv_usec = to.tv_usec - tv.tv_usec;
if (tv.tv_usec < 0) {
tv.tv_usec += 1000000;
tv.tv_sec--;
}
if (tv.tv_sec < 0)
break;
FD_SET(s, &fdset);
if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
iderror(0, 0, s, ID_UNKNOWN);
if (ioctl(s, FIONREAD, &onreadlen) == -1)
iderror(0, 0, s, ID_UNKNOWN);
if ((size_t)onreadlen > bufsiz)
onreadlen = bufsiz;
ssize = read(s, &buf[size], (size_t)onreadlen);
if (ssize == -1)
iderror(0, 0, s, ID_UNKNOWN);
else if (ssize == 0)
break;
bufsiz -= ssize;
size += ssize;
if (memchr(&buf[size - ssize], '\n', ssize) != NULL)
break;
}
buf[size] = '\0';
/* Read two characters, and check for a delimiting character */
if (sscanf(buf, "%hu , %hu%c", &lport, &fport, &e) != 3 || isdigit(e))
iderror(0, 0, s, ID_INVALID);
/* Send garbage? */
if (gflag)
goto printit;
/*
* If not "real" (-r), send a HIDDEN-USER error for everything.
* If -d is used to set a fallback username, this is used to
* override it, and the fallback is returned instead.
*/
if (!rflag) {
if (*idbuf == '\0')
iderror(lport, fport, s, ID_HIDDEN);
goto printit;
}
/*
* We take the input and construct an array of two sockaddr_ins
* which contain the local address information and foreign
* address information, respectively, used to look up the
* credentials for the socket (which are returned by the
* sysctl "net.inet.tcp.getcred" when we call it.)
*/
socklen = sizeof(ss[0]);
if (getsockname(s, (struct sockaddr *)&ss[0], &socklen) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
socklen = sizeof(ss[1]);
if (getpeername(s, (struct sockaddr *)&ss[1], &socklen) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
if (ss[0].ss_family != ss[1].ss_family)
iderror(lport, fport, s, ID_UNKNOWN);
size = sizeof(uc);
switch (ss[0].ss_family) {
case AF_INET:
sin4[0] = *(struct sockaddr_in *)&ss[0];
sin4[0].sin_port = htons(lport);
sin4[1] = *(struct sockaddr_in *)&ss[1];
sin4[1].sin_port = htons(fport);
if (sysctlbyname("net.inet.tcp.getcred", &uc, &size, sin4,
sizeof(sin4)) == -1)
getcredfail = errno;
break;
#ifdef INET6
case AF_INET6:
sin6[0] = *(struct sockaddr_in6 *)&ss[0];
sin6[0].sin6_port = htons(lport);
sin6[1] = *(struct sockaddr_in6 *)&ss[1];
sin6[1].sin6_port = htons(fport);
if (sysctlbyname("net.inet6.tcp6.getcred", &uc, &size, sin6,
sizeof(sin6)) == -1)
getcredfail = errno;
break;
#endif
default: /* should not reach here */
getcredfail = EAFNOSUPPORT;
break;
}
if (getcredfail != 0 || uc.cr_version != XUCRED_VERSION) {
if (*idbuf == '\0')
iderror(lport, fport, s,
getcredfail == ENOENT ? ID_NOUSER : ID_UNKNOWN);
goto printit;
}
/* Look up the pw to get the username and home directory*/
errno = 0;
pw = getpwuid(uc.cr_uid);
if (pw == NULL)
iderror(lport, fport, s, errno == 0 ? ID_NOUSER : ID_UNKNOWN);
if (iflag)
snprintf(idbuf, sizeof(idbuf), "%u", (unsigned)pw->pw_uid);
else
strlcpy(idbuf, pw->pw_name, sizeof(idbuf));
/*
* If enabled, we check for a file named ".noident" in the user's
* home directory. If found, we return HIDDEN-USER.
*/
if (nflag) {
if (asprintf(&p, "%s/.noident", pw->pw_dir) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
if (lstat(p, &sb) == 0) {
free(p);
iderror(lport, fport, s, ID_HIDDEN);
}
free(p);
}
/*
* Here, if enabled, we read a user's ".fakeid" file in their
* home directory. It consists of a line containing the name
* they want.
*/
if (fflag) {
int fakeid_fd;
/*
* Here we set ourself to effectively be the user, so we don't
* open any files we have no permission to open, especially
* symbolic links to sensitive root-owned files or devices.
*/
if (initgroups(pw->pw_name, pw->pw_gid) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
if (seteuid(pw->pw_uid) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
/*
* We can't stat() here since that would be a race
* condition.
* Therefore, we open the file we have permissions to open
* and if it's not a regular file, we close it and end up
* returning the user's real username.
*/
if (asprintf(&p, "%s/.fakeid", pw->pw_dir) == -1)
iderror(lport, fport, s, ID_UNKNOWN);
fakeid_fd = open(p, O_RDONLY | O_NONBLOCK);
free(p);
if (fakeid_fd == -1 || fstat(fakeid_fd, &sb) == -1 ||
!S_ISREG(sb.st_mode))
goto fakeid_fail;
if ((ssize = read(fakeid_fd, buf, sizeof(buf) - 1)) < 0)
goto fakeid_fail;
buf[ssize] = '\0';
/*
* Usually, the file will have the desired identity
* in the form "identity\n". Allow for leading white
* space and trailing white space/end of line.
*/
p = buf;
p += strspn(p, " \t");
p[strcspn(p, " \t\r\n")] = '\0';
if (strlen(p) > MAXLOGNAME - 1) /* Too long (including nul)? */
p[MAXLOGNAME - 1] = '\0';
/*
* If the name is a zero-length string or matches it
* the id or name of another user (unless permitted by -F)
* then it is invalid.
*/
if (*p == '\0')
goto fakeid_fail;
if (!Fflag) {
if (iflag) {
if (p[strspn(p, "0123456789")] == '\0' &&
getpwuid(atoi(p)) != NULL)
goto fakeid_fail;
} else {
if (getpwnam(p) != NULL)
goto fakeid_fail;
}
}
strlcpy(idbuf, p, sizeof(idbuf));
fakeid_fail:
if (fakeid_fd != -1)
close(fakeid_fd);
}
printit:
/* Finally, we make and send the reply. */
if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
idbuf) == -1) {
syslog(LOG_ERR, "asprintf: %m");
exit(EX_OSERR);
}
send(s, p, strlen(p), MSG_EOF);
free(p);
exit(0);
}
/*
* RFC738 Time Server.
* Return a machine readable date and time, in the form of the
* number of seconds since midnight, Jan 1, 1900. Since gettimeofday
* returns the number of seconds since midnight, Jan 1, 1970,
* we must add 2208988800 seconds to this figure to make up for
* some seventy years Bell Labs was asleep.
*/
unsigned long
machtime(void)
{
struct timeval tv;
if (gettimeofday(&tv, (struct timezone *)NULL) < 0) {
if (debug)
warnx("unable to get time of day");
return (0L);
}
#define OFFSET ((u_long)25567 * 24*60*60)
return (htonl((long)(tv.tv_sec + OFFSET)));
#undef OFFSET
}
/* ARGSUSED */
void
machtime_dg(int s, struct servtab *sep)
{
unsigned long result;
struct sockaddr_storage ss;
socklen_t size;
size = sizeof(ss);
if (recvfrom(s, (char *)&result, sizeof(result), 0,
(struct sockaddr *)&ss, &size) < 0)
return;
if (check_loop((struct sockaddr *)&ss, sep))
return;
result = machtime();
(void) sendto(s, (char *) &result, sizeof(result), 0,
(struct sockaddr *)&ss, size);
}
/* ARGSUSED */
void
machtime_stream(int s, struct servtab *sep __unused)
{
unsigned long result;
result = machtime();
(void) send(s, (char *) &result, sizeof(result), MSG_EOF);
}
/*
* RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
* services based on the service name sent.
*
* Based on TCPMUX.C by Mark K. Lottor November 1988
* sri-nic::ps:<mkl>tcpmux.c
*/
#define MAX_SERV_LEN (256+2) /* 2 bytes for \r\n */
#define strwrite(fd, buf) (void) write(fd, buf, sizeof(buf)-1)
static int /* # of characters upto \r,\n or \0 */
getline(int fd, char *buf, int len)
{
int count = 0, n;
struct sigaction sa;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sa.sa_handler = SIG_DFL;
sigaction(SIGALRM, &sa, (struct sigaction *)0);
do {
alarm(10);
n = read(fd, buf, len-count);
alarm(0);
if (n == 0)
return (count);
if (n < 0)
return (-1);
while (--n >= 0) {
if (*buf == '\r' || *buf == '\n' || *buf == '\0')
return (count);
count++;
buf++;
}
} while (count < len);
return (count);
}
struct servtab *
tcpmux(int s)
{
struct servtab *sep;
char service[MAX_SERV_LEN+1];
int len;
/* Get requested service name */
if ((len = getline(s, service, MAX_SERV_LEN)) < 0) {
strwrite(s, "-Error reading service name\r\n");
return (NULL);
}
service[len] = '\0';
if (debug)
warnx("tcpmux: someone wants %s", service);
/*
* Help is a required command, and lists available services,
* one per line.
*/
if (!strcasecmp(service, "help")) {
for (sep = servtab; sep; sep = sep->se_next) {
if (!ISMUX(sep))
continue;
(void)write(s,sep->se_service,strlen(sep->se_service));
strwrite(s, "\r\n");
}
return (NULL);
}
/* Try matching a service in inetd.conf with the request */
for (sep = servtab; sep; sep = sep->se_next) {
if (!ISMUX(sep))
continue;
if (!strcasecmp(service, sep->se_service)) {
if (ISMUXPLUS(sep)) {
strwrite(s, "+Go\r\n");
}
return (sep);
}
}
strwrite(s, "-Service not available\r\n");
return (NULL);
}