/* $OpenBSD: rcmdsh.c,v 1.5 1998/04/25 16:23:58 millert Exp $ */ /* * This is an rcmd() replacement originally by * Chris Siebenmann . * * $FreeBSD: head/lib/libc/net/rcmdsh.c 85342 2001-10-23 06:22:15Z imp $ */ #if defined(LIBC_SCCS) && !defined(lint) static char *rcsid = "$FreeBSD: head/lib/libc/net/rcmdsh.c 85342 2001-10-23 06:22:15Z imp $" #endif /* LIBC_SCCS and not lint */ #include #include #include #include #include #include #include #include #include #include #include #ifndef _PATH_RSH #define _PATH_RSH "/usr/bin/rsh" #endif /* * This is a replacement rcmd() function that uses the rsh(1) * program in place of a direct rcmd(3) function call so as to * avoid having to be root. Note that rport is ignored. */ /* ARGSUSED */ int rcmdsh(ahost, rport, locuser, remuser, cmd, rshprog) char **ahost; int rport; const char *locuser, *remuser, *cmd; char *rshprog; { struct hostent *hp; int cpid, sp[2]; char *p; struct passwd *pw; /* What rsh/shell to use. */ if (rshprog == NULL) rshprog = _PATH_RSH; /* locuser must exist on this host. */ if ((pw = getpwnam(locuser)) == NULL) { (void) fprintf(stderr, "rcmdsh: unknown user: %s\n", locuser); return(-1); } /* Validate remote hostname. */ if (strcmp(*ahost, "localhost") != 0) { if ((hp = gethostbyname(*ahost)) == NULL) { herror(*ahost); return(-1); } *ahost = hp->h_name; } /* Get a socketpair we'll use for stdin and stdout. */ if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, sp) < 0) { perror("rcmdsh: socketpair"); return(-1); } cpid = fork(); if (cpid < 0) { perror("rcmdsh: fork failed"); return(-1); } else if (cpid == 0) { /* * Child. We use sp[1] to be stdin/stdout, and close sp[0]. */ (void) close(sp[0]); if (dup2(sp[1], 0) < 0 || dup2(0, 1) < 0) { perror("rcmdsh: dup2 failed"); _exit(255); } /* Fork again to lose parent. */ cpid = fork(); if (cpid < 0) { perror("rcmdsh: fork to lose parent failed"); _exit(255); } if (cpid > 0) _exit(0); /* In grandchild here. Become local user for rshprog. */ if (setuid(pw->pw_uid)) { (void) fprintf(stderr, "rcmdsh: setuid(%u): %s\n", pw->pw_uid, strerror(errno)); _exit(255); } /* * If remote host is "localhost" and local and remote user * are the same, avoid running remote shell for efficiency. */ if (!strcmp(*ahost, "localhost") && !strcmp(locuser, remuser)) { if (pw->pw_shell[0] == '\0') rshprog = _PATH_BSHELL; else rshprog = pw->pw_shell; p = strrchr(rshprog, '/'); execlp(rshprog, p ? p+1 : rshprog, "-c", cmd, (char *) NULL); } else { p = strrchr(rshprog, '/'); execlp(rshprog, p ? p+1 : rshprog, *ahost, "-l", remuser, cmd, (char *) NULL); } (void) fprintf(stderr, "rcmdsh: execlp %s failed: %s\n", rshprog, strerror(errno)); _exit(255); } else { /* Parent. close sp[1], return sp[0]. */ (void) close(sp[1]); /* Reap child. */ (void) wait(NULL); return(sp[0]); } /* NOTREACHED */ }