131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
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/* $OpenBSD: rcmdsh.c,v 1.5 1998/04/25 16:23:58 millert Exp $ */
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/*
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* This is an rcmd() replacement originally by
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* Chris Siebenmann <cks@utcc.utoronto.ca>.
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*
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* $FreeBSD$
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char *rcsid = "$FreeBSD$"
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <signal.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <string.h>
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#include <pwd.h>
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#include <paths.h>
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#include <unistd.h>
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#ifndef _PATH_RSH
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#define _PATH_RSH "/usr/bin/rsh"
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#endif
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/*
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* This is a replacement rcmd() function that uses the rsh(1)
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* program in place of a direct rcmd(3) function call so as to
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* avoid having to be root. Note that rport is ignored.
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*/
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/* ARGSUSED */
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int
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rcmdsh(ahost, rport, locuser, remuser, cmd, rshprog)
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char **ahost;
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int rport;
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const char *locuser, *remuser, *cmd;
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char *rshprog;
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{
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struct hostent *hp;
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int cpid, sp[2];
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char *p;
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struct passwd *pw;
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/* What rsh/shell to use. */
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if (rshprog == NULL)
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rshprog = _PATH_RSH;
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/* locuser must exist on this host. */
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if ((pw = getpwnam(locuser)) == NULL) {
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(void) fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser);
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return(-1);
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}
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/* Validate remote hostname. */
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if (strcmp(*ahost, "localhost") != 0) {
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if ((hp = gethostbyname(*ahost)) == NULL) {
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herror(*ahost);
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return(-1);
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}
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*ahost = hp->h_name;
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}
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/* Get a socketpair we'll use for stdin and stdout. */
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if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) < 0) {
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perror("rcmdsh: socketpair");
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return(-1);
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}
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cpid = fork();
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if (cpid < 0) {
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perror("rcmdsh: fork failed");
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return(-1);
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} else if (cpid == 0) {
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/*
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* Child. We use sp[1] to be stdin/stdout, and close sp[0].
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*/
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(void) close(sp[0]);
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if (dup2(sp[1], 0) < 0 || dup2(0, 1) < 0) {
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perror("rcmdsh: dup2 failed");
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_exit(255);
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}
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/* Fork again to lose parent. */
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cpid = fork();
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if (cpid < 0) {
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perror("rcmdsh: fork to lose parent failed");
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_exit(255);
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}
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if (cpid > 0)
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_exit(0);
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/* In grandchild here. Become local user for rshprog. */
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if (setuid(pw->pw_uid)) {
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(void) fprintf(stderr, "rcmdsh: setuid(%u): %s\n",
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pw->pw_uid, strerror(errno));
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_exit(255);
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}
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/*
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* If remote host is "localhost" and local and remote user
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* are the same, avoid running remote shell for efficiency.
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*/
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if (!strcmp(*ahost, "localhost") && !strcmp(locuser, remuser)) {
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if (pw->pw_shell[0] == '\0')
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rshprog = _PATH_BSHELL;
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else
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rshprog = pw->pw_shell;
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p = strrchr(rshprog, '/');
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execlp(rshprog, p ? p+1 : rshprog, "-c", cmd,
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(char *) NULL);
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} else {
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p = strrchr(rshprog, '/');
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execlp(rshprog, p ? p+1 : rshprog, *ahost, "-l",
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remuser, cmd, (char *) NULL);
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}
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(void) fprintf(stderr, "rcmdsh: execlp %s failed: %s\n",
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rshprog, strerror(errno));
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_exit(255);
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} else {
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/* Parent. close sp[1], return sp[0]. */
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(void) close(sp[1]);
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/* Reap child. */
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(void) wait(NULL);
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return(sp[0]);
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}
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/* NOTREACHED */
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}
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