NetBSD/lib/libc/net/rcmd.c

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/* $NetBSD: rcmd.c,v 1.23 1998/01/18 06:22:19 lukem Exp $ */
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/*
* Copyright (c) 1997 Matthew R. Green.
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* Copyright (c) 1983, 1993, 1994
* The Regents of the University of California. All rights reserved.
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*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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>
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#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)rcmd.c 8.3 (Berkeley) 3/26/94";
#else
__RCSID("$NetBSD: rcmd.c,v 1.23 1998/01/18 06:22:19 lukem Exp $");
#endif
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#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
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#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
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#include <sys/poll.h>
#include <sys/wait.h>
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#include <netinet/in.h>
#include <rpc/rpc.h>
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#include <arpa/inet.h>
#include <netgroup.h>
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#include <signal.h>
#include <fcntl.h>
#include <netdb.h>
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#include <unistd.h>
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#include <pwd.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <syslog.h>
#include <stdlib.h>
#include <paths.h>
#include <err.h>
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#include "pathnames.h"
int orcmd __P((char **, u_short, const char *, const char *, const char *,
int *));
int __ivaliduser __P((FILE *, u_int32_t, const char *, const char *));
static int rshrcmd __P((char **, u_short, const char *, const char *,
const char *, int *, char *));
static int hprcmd __P((struct hostent *, char **, u_short, const char *,
const char *, const char *, int *));
static int __icheckhost __P((u_int32_t, const char *));
static char *__gethostloop __P((u_int32_t));
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int
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rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
char **ahost;
u_short rport;
const char *locuser, *remuser, *cmd;
int *fd2p;
{
struct hostent *hp;
struct servent *sp;
/*
* Canonicalise hostname.
* XXX: Should we really do this?
*/
hp = gethostbyname(*ahost);
if (hp == NULL) {
herror(*ahost);
return (-1);
}
*ahost = hp->h_name;
/*
* Check if rport is the same as the shell port, and that the fd2p. If
* it is not, the program isn't expecting 'rsh' and so we can't use the
* RCMD_CMD environment.
*/
sp = getservbyname("shell", "tcp");
if (sp != NULL && sp->s_port == rport)
return (rshrcmd(ahost, rport, locuser, remuser, cmd, fd2p,
getenv("RCMD_CMD")));
else
return (hprcmd(hp, ahost, rport, locuser, remuser, cmd, fd2p));
}
/* this is simply a wrapper around hprcmd() that handles ahost first */
int
orcmd(ahost, rport, locuser, remuser, cmd, fd2p)
char **ahost;
u_short rport;
const char *locuser, *remuser, *cmd;
int *fd2p;
{
struct hostent *hp;
hp = gethostbyname(*ahost);
if (hp == NULL) {
herror(*ahost);
return (-1);
}
*ahost = hp->h_name;
return (hprcmd(hp, ahost, rport, locuser, remuser, cmd, fd2p));
}
static int
hprcmd(hp, ahost, rport, locuser, remuser, cmd, fd2p)
struct hostent *hp;
char **ahost;
u_short rport;
const char *locuser, *remuser, *cmd;
int *fd2p;
{
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struct sockaddr_in sin, from;
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struct pollfd reads[2];
int oldmask;
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pid_t pid;
int s, lport, timo;
int pollr;
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char c;
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pid = getpid();
oldmask = sigblock(sigmask(SIGURG));
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for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
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s = rresvport(&lport);
if (s < 0) {
if (errno == EAGAIN)
warnx("rcmd: socket: All ports in use");
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else
warn("rcmd: socket");
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sigsetmask(oldmask);
return (-1);
}
fcntl(s, F_SETOWN, pid);
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sin.sin_len = sizeof(struct sockaddr_in);
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sin.sin_family = hp->h_addrtype;
sin.sin_port = rport;
memmove(&sin.sin_addr, hp->h_addr_list[0], hp->h_length);
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if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
break;
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(void)close(s);
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if (errno == EADDRINUSE) {
lport--;
continue;
}
if (errno == ECONNREFUSED && timo <= 16) {
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(void)sleep(timo);
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timo *= 2;
continue;
}
if (hp->h_addr_list[1] != NULL) {
int oerrno = errno;
warnx("rcmd: connect to address %s",
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inet_ntoa(sin.sin_addr));
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errno = oerrno;
perror(0);
hp->h_addr_list++;
memmove(&sin.sin_addr, hp->h_addr_list[0],
hp->h_length);
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(void)fprintf(stderr, "Trying %s...\n",
inet_ntoa(sin.sin_addr));
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continue;
}
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(void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno));
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sigsetmask(oldmask);
return (-1);
}
lport--;
if (fd2p == 0) {
write(s, "", 1);
lport = 0;
} else {
char num[8];
int s2 = rresvport(&lport), s3;
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int len = sizeof(from);
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if (s2 < 0)
goto bad;
listen(s2, 1);
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(void)snprintf(num, sizeof(num), "%d", lport);
if (write(s, num, strlen(num) + 1) != strlen(num) + 1) {
warn("rcmd: write (setting up stderr)");
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(void)close(s2);
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goto bad;
}
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reads[0].fd = s;
reads[0].events = POLLIN;
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reads[1].fd = s2;
reads[1].events = POLLIN;
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errno = 0;
pollr = poll(reads, 2, INFTIM);
if (pollr < 1 || (reads[1].revents & POLLIN) == 0) {
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if (errno != 0)
warn("poll: setting up stderr");
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else
warnx("poll: protocol failure in circuit setup");
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(void)close(s2);
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goto bad;
}
s3 = accept(s2, (struct sockaddr *)&from, &len);
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(void)close(s2);
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if (s3 < 0) {
warn("rcmd: accept");
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lport = 0;
goto bad;
}
*fd2p = s3;
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from.sin_port = ntohs(from.sin_port);
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if (from.sin_family != AF_INET ||
from.sin_port >= IPPORT_RESERVED ||
from.sin_port < IPPORT_RESERVED / 2) {
warnx("rcmd: protocol failure in circuit setup.");
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goto bad2;
}
}
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(void)write(s, locuser, strlen(locuser)+1);
(void)write(s, remuser, strlen(remuser)+1);
(void)write(s, cmd, strlen(cmd)+1);
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if (read(s, &c, 1) != 1) {
warn("%s", *ahost);
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goto bad2;
}
if (c != 0) {
while (read(s, &c, 1) == 1) {
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(void)write(STDERR_FILENO, &c, 1);
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if (c == '\n')
break;
}
goto bad2;
}
sigsetmask(oldmask);
return (s);
bad2:
if (lport)
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(void)close(*fd2p);
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bad:
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(void)close(s);
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sigsetmask(oldmask);
return (-1);
}
/*
* based on code written by Chris Siebenmann <cks@utcc.utoronto.ca>
*/
static int
rshrcmd(ahost, rport, locuser, remuser, cmd, fd2p, rshcmd)
char **ahost;
u_short rport;
const char *locuser, *remuser, *cmd;
int *fd2p;
char *rshcmd;
{
pid_t pid;
int sp[2], ep[2];
char *p;
struct passwd *pw;
/* What rsh/shell to use. */
if (rshcmd == NULL)
rshcmd = _PATH_BIN_RCMD;
/* locuser must exist on this host. */
if ((pw = getpwnam(locuser)) == NULL) {
warnx("rshrcmd: unknown user: %s", locuser);
return(-1);
}
/* get a socketpair we'll use for stdin and stdout. */
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) {
warn("rshrcmd: socketpair");
return (-1);
}
/* we will use this for the fd2 pointer */
if (fd2p) {
if (socketpair(AF_UNIX, SOCK_STREAM, 0, ep) < 0) {
warn("rshrcmd: socketpair");
return (-1);
}
*fd2p = ep[0];
}
pid = fork();
if (pid < 0) {
warn("rshrcmd: fork");
return (-1);
}
if (pid == 0) {
/*
* child
* - we use sp[1] to be stdin/stdout, and close sp[0]
* - with fd2p, we use ep[1] for stderr, and close ep[0]
*/
(void)close(sp[0]);
if (dup2(sp[1], 0) < 0 || dup2(0, 1) < 0) {
warn("rshrcmd: dup2");
_exit(1);
}
if (fd2p) {
if (dup2(ep[1], 2) < 0) {
warn("rshrcmd: dup2");
_exit(1);
}
(void)close(ep[0]);
(void)close(ep[1]);
} else if (dup2(0, 2) < 0) {
warn("rshrcmd: dup2");
_exit(1);
}
/* fork again to lose parent. */
pid = fork();
if (pid < 0) {
warn("rshrcmd: second fork");
_exit(1);
}
if (pid > 0)
_exit(0);
/* Orphan. Become local user for rshprog. */
if (setuid(pw->pw_uid)) {
warn("rshrcmd: setuid(%u)", pw->pw_uid);
_exit(1);
}
/*
* If we are rcmd'ing to "localhost" as the same user as we are,
* then avoid running remote shell for efficiency.
*/
if (strcmp(*ahost, "localhost") == 0 &&
strcmp(locuser, remuser) == 0) {
if (pw->pw_shell[0] == '\0')
rshcmd = _PATH_BSHELL;
else
rshcmd = pw->pw_shell;
p = strrchr(rshcmd, '/');
execlp(rshcmd, p ? p + 1 : rshcmd, "-c", cmd, NULL);
} else {
p = strrchr(rshcmd, '/');
execlp(rshcmd, p ? p + 1 : rshcmd, *ahost, "-l",
remuser, cmd, NULL);
}
warn("rshrcmd: exec %s", rshcmd);
_exit(1);
}
/* Parent */
(void)close(sp[1]);
if (fd2p)
(void)close(ep[1]);
(void)waitpid(pid, NULL, 0);
return (sp[0]);
}
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int
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rresvport(alport)
int *alport;
{
struct sockaddr_in sin;
int s;
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sin.sin_len = sizeof(struct sockaddr_in);
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sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0)
return (-1);
#if 0
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for (;;) {
sin.sin_port = htons((u_short)*alport);
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if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
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return (s);
if (errno != EADDRINUSE) {
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(void)close(s);
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return (-1);
}
(*alport)--;
if (*alport == IPPORT_RESERVED/2) {
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(void)close(s);
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errno = EAGAIN; /* close */
return (-1);
}
}
#else
sin.sin_port = 0;
if (bindresvport(s, &sin) < 0) {
int sverr = errno;
(void)close(s);
errno = sverr;
return (-1);
}
*alport = (int)ntohs(sin.sin_port);
return (s);
#endif
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}
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int __check_rhosts_file = 1;
char *__rcmd_errstr;
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int
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ruserok(rhost, superuser, ruser, luser)
const char *rhost, *ruser, *luser;
int superuser;
{
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struct hostent *hp;
char **ap;
int i;
#define MAXADDRS 35
u_int32_t addrs[MAXADDRS + 1];
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if ((hp = gethostbyname(rhost)) == NULL)
return (-1);
for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i)
memmove(&addrs[i], *ap, sizeof(addrs[i]));
addrs[i] = 0;
for (i = 0; i < MAXADDRS && addrs[i]; i++)
if (iruserok(addrs[i], superuser, ruser, luser) == 0)
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return (0);
return (-1);
}
/*
* New .rhosts strategy: We are passed an ip address. We spin through
* hosts.equiv and .rhosts looking for a match. When the .rhosts only
* has ip addresses, we don't have to trust a nameserver. When it
* contains hostnames, we spin through the list of addresses the nameserver
* gives us and look for a match.
*
* Returns 0 if ok, -1 if not ok.
*/
int
iruserok(raddr, superuser, ruser, luser)
u_int32_t raddr;
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int superuser;
const char *ruser, *luser;
{
register char *cp;
struct stat sbuf;
struct passwd *pwd;
FILE *hostf;
uid_t uid;
gid_t gid;
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int first;
char pbuf[MAXPATHLEN];
first = 1;
hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r");
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again:
if (hostf) {
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if (__ivaliduser(hostf, raddr, luser, ruser) == 0) {
(void)fclose(hostf);
return (0);
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}
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(void)fclose(hostf);
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}
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if (first == 1 && (__check_rhosts_file || superuser)) {
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first = 0;
if ((pwd = getpwnam(luser)) == NULL)
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return (-1);
(void)strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1);
(void)strncat(pbuf, "/.rhosts", sizeof(pbuf) - strlen(pbuf) - 1);
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/*
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* Change effective uid while opening .rhosts. If root and
* reading an NFS mounted file system, can't read files that
* are protected read/write owner only.
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*/
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uid = geteuid();
gid = getegid();
(void)setegid(pwd->pw_gid);
initgroups(pwd->pw_name, pwd->pw_gid);
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(void)seteuid(pwd->pw_uid);
hostf = fopen(pbuf, "r");
(void)seteuid(uid);
(void)setegid(gid);
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if (hostf == NULL)
return (-1);
/*
* If not a regular file, or is owned by someone other than
* user or root or if writeable by anyone but the owner, quit.
*/
cp = NULL;
if (lstat(pbuf, &sbuf) < 0)
cp = ".rhosts lstat failed";
else if (!S_ISREG(sbuf.st_mode))
cp = ".rhosts not regular file";
else if (fstat(fileno(hostf), &sbuf) < 0)
cp = ".rhosts fstat failed";
else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
cp = "bad .rhosts owner";
else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
cp = ".rhosts writeable by other than owner";
/* If there were any problems, quit. */
if (cp) {
__rcmd_errstr = cp;
(void)fclose(hostf);
return (-1);
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}
goto again;
}
return (-1);
}
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/*
* XXX
* Don't make static, used by lpd(8).
*
* Returns 0 if ok, -1 if not ok.
*/
int
__ivaliduser(hostf, raddr, luser, ruser)
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FILE *hostf;
u_int32_t raddr;
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const char *luser, *ruser;
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{
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register char *user, *p;
int ch;
char buf[MAXHOSTNAMELEN + 128]; /* host + login */
const char *auser, *ahost;
int hostok, userok;
char *rhost = NULL;
int firsttime = 1;
char domain[MAXHOSTNAMELEN];
getdomainname(domain, sizeof(domain));
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while (fgets(buf, sizeof(buf), hostf)) {
p = buf;
/* Skip lines that are too long. */
if (strchr(p, '\n') == NULL) {
while ((ch = getc(hostf)) != '\n' && ch != EOF)
;
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continue;
}
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while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') {
*p = isupper(*p) ? tolower(*p) : *p;
p++;
}
if (*p == ' ' || *p == '\t') {
*p++ = '\0';
while (*p == ' ' || *p == '\t')
p++;
user = p;
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while (*p != '\n' && *p != ' ' &&
*p != '\t' && *p != '\0')
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p++;
} else
user = p;
*p = '\0';
if (p == buf)
continue;
auser = *user ? user : luser;
ahost = buf;
if (ahost[0] == '+')
switch (ahost[1]) {
case '\0':
hostok = 1;
break;
case '@':
if (firsttime) {
rhost = __gethostloop(raddr);
firsttime = 0;
}
if (rhost)
hostok = innetgr(&ahost[2], rhost,
NULL, domain);
else
hostok = 0;
break;
default:
hostok = __icheckhost(raddr, &ahost[1]);
break;
}
else if (ahost[0] == '-')
switch (ahost[1]) {
case '\0':
hostok = -1;
break;
case '@':
if (firsttime) {
rhost = __gethostloop(raddr);
firsttime = 0;
}
if (rhost)
hostok = -innetgr(&ahost[2], rhost,
NULL, domain);
else
hostok = 0;
break;
default:
hostok = -__icheckhost(raddr, &ahost[1]);
break;
}
else
hostok = __icheckhost(raddr, ahost);
if (auser[0] == '+')
switch (auser[1]) {
case '\0':
userok = 1;
break;
case '@':
userok = innetgr(&auser[2], NULL, ruser,
domain);
break;
default:
userok = strcmp(ruser, &auser[1]) == 0;
break;
}
else if (auser[0] == '-')
switch (auser[1]) {
case '\0':
userok = -1;
break;
case '@':
userok = -innetgr(&auser[2], NULL, ruser,
domain);
break;
default:
userok = -(strcmp(ruser, &auser[1]) == 0);
break;
}
else
userok = strcmp(ruser, auser) == 0;
/* Check if one component did not match */
if (hostok == 0 || userok == 0)
continue;
/* Check if we got a forbidden pair */
if (userok == -1 || hostok == -1)
return -1;
/* Check if we got a valid pair */
if (hostok == 1 && userok == 1)
return 0;
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}
return -1;
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}
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/*
* Returns "true" if match, 0 if no match.
*/
static int
__icheckhost(raddr, lhost)
u_int32_t raddr;
const char *lhost;
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{
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struct hostent *hp;
struct in_addr laddr;
char **pp;
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/* Try for raw ip address first. */
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if (isdigit(*lhost) && inet_aton(lhost, &laddr) != 0)
return (raddr == laddr.s_addr);
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/* Better be a hostname. */
if ((hp = gethostbyname(lhost)) == NULL)
return (0);
/* Spin through ip addresses. */
for (pp = hp->h_addr_list; *pp; ++pp)
if (!memcmp(&raddr, *pp, sizeof(u_int32_t)))
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return (1);
/* No match. */
return (0);
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}
/*
* Return the hostname associated with the supplied address.
* Do a reverse lookup as well for security. If a loop cannot
* be found, pack the result of inet_ntoa() into the string.
*/
static char *
__gethostloop(raddr)
u_int32_t raddr;
{
static char remotehost[MAXHOSTNAMELEN];
struct hostent *hp;
struct in_addr in;
hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET);
if (hp == NULL)
return (NULL);
/*
* Look up the name and check that the supplied
* address is in the list
*/
strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1);
remotehost[sizeof(remotehost) - 1] = '\0';
hp = gethostbyname(remotehost);
if (hp == NULL)
return (NULL);
for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++)
if (!memcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr)))
return (remotehost);
/*
* either the DNS adminstrator has made a configuration
* mistake, or someone has attempted to spoof us
*/
in.s_addr = raddr;
syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s",
inet_ntoa(in), hp->h_name);
return (NULL);
}