popen.c revision 262435 
1/*
2 * Copyright (c) 1988, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software written by Ken Arnold and
6 * published in UNIX Review, Vol. 6, No. 8.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#ifndef lint
34#if 0
35static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 4/6/94";
36#endif
37#endif /* not lint */
38
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: stable/10/libexec/ftpd/popen.c 262435 2014-02-24 08:21:49Z brueffer $");
41
42#include <sys/types.h>
43#include <sys/wait.h>
44#include <netinet/in.h>
45
46#include <errno.h>
47#include <glob.h>
48#include <signal.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52#include <unistd.h>
53
54#include "extern.h"
55#include "pathnames.h"
56#include <syslog.h>
57#include <time.h>
58
59#define	MAXUSRARGS	100
60#define	MAXGLOBARGS	1000
61
62/*
63 * Special version of popen which avoids call to shell.  This ensures noone
64 * may create a pipe to a hidden program as a side effect of a list or dir
65 * command.
66 */
67static int *pids;
68static int fds;
69
70FILE *
71ftpd_popen(char *program, char *type)
72{
73	char *cp;
74	FILE *iop;
75	int argc, gargc, pdes[2], pid;
76	char **pop, *argv[MAXUSRARGS], *gargv[MAXGLOBARGS];
77
78	if (((*type != 'r') && (*type != 'w')) || type[1])
79		return (NULL);
80
81	if (!pids) {
82		if ((fds = getdtablesize()) <= 0)
83			return (NULL);
84		if ((pids = malloc(fds * sizeof(int))) == NULL)
85			return (NULL);
86		memset(pids, 0, fds * sizeof(int));
87	}
88	if (pipe(pdes) < 0)
89		return (NULL);
90
91	/* break up string into pieces */
92	for (argc = 0, cp = program; argc < MAXUSRARGS; cp = NULL) {
93		if (!(argv[argc++] = strtok(cp, " \t\n")))
94			break;
95	}
96	argv[argc - 1] = NULL;
97
98	/* glob each piece */
99	gargv[0] = argv[0];
100	for (gargc = argc = 1; argv[argc] && gargc < (MAXGLOBARGS-1); argc++) {
101		glob_t gl;
102		int flags = GLOB_BRACE|GLOB_NOCHECK|GLOB_TILDE;
103
104		memset(&gl, 0, sizeof(gl));
105		gl.gl_matchc = MAXGLOBARGS;
106		flags |= GLOB_LIMIT;
107		if (glob(argv[argc], flags, NULL, &gl))
108			gargv[gargc++] = strdup(argv[argc]);
109		else if (gl.gl_pathc > 0) {
110			for (pop = gl.gl_pathv; *pop && gargc < (MAXGLOBARGS-1);
111			     pop++)
112				gargv[gargc++] = strdup(*pop);
113		}
114		globfree(&gl);
115	}
116	gargv[gargc] = NULL;
117
118	iop = NULL;
119	fflush(NULL);
120	pid = (strcmp(gargv[0], _PATH_LS) == 0) ? fork() : vfork();
121	switch(pid) {
122	case -1:			/* error */
123		(void)close(pdes[0]);
124		(void)close(pdes[1]);
125		goto pfree;
126		/* NOTREACHED */
127	case 0:				/* child */
128		if (*type == 'r') {
129			if (pdes[1] != STDOUT_FILENO) {
130				dup2(pdes[1], STDOUT_FILENO);
131				(void)close(pdes[1]);
132			}
133			dup2(STDOUT_FILENO, STDERR_FILENO); /* stderr too! */
134			(void)close(pdes[0]);
135		} else {
136			if (pdes[0] != STDIN_FILENO) {
137				dup2(pdes[0], STDIN_FILENO);
138				(void)close(pdes[0]);
139			}
140			(void)close(pdes[1]);
141		}
142		/* Drop privileges before proceeding */
143		if (getuid() != geteuid() && setuid(geteuid()) < 0)
144			_exit(1);
145		if (strcmp(gargv[0], _PATH_LS) == 0) {
146			/* Reset getopt for ls_main() */
147			optreset = optind = optopt = 1;
148			/* Close syslogging to remove pwd.db missing msgs */
149			closelog();
150			/* Trigger to sense new /etc/localtime after chroot */
151			if (getenv("TZ") == NULL) {
152				setenv("TZ", "", 0);
153				tzset();
154				unsetenv("TZ");
155				tzset();
156			}
157			exit(ls_main(gargc, gargv));
158		}
159		execv(gargv[0], gargv);
160		_exit(1);
161	}
162	/* parent; assume fdopen can't fail...  */
163	if (*type == 'r') {
164		iop = fdopen(pdes[0], type);
165		(void)close(pdes[1]);
166	} else {
167		iop = fdopen(pdes[1], type);
168		(void)close(pdes[0]);
169	}
170	pids[fileno(iop)] = pid;
171
172pfree:	for (argc = 1; gargv[argc] != NULL; argc++)
173		free(gargv[argc]);
174
175	return (iop);
176}
177
178int
179ftpd_pclose(FILE *iop)
180{
181	int fdes, omask, status;
182	pid_t pid;
183
184	/*
185	 * pclose returns -1 if stream is not associated with a
186	 * `popened' command, or, if already `pclosed'.
187	 */
188	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
189		return (-1);
190	(void)fclose(iop);
191	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
192	while ((pid = waitpid(pids[fdes], &status, 0)) < 0 && errno == EINTR)
193		continue;
194	(void)sigsetmask(omask);
195	pids[fdes] = 0;
196	if (pid < 0)
197		return (pid);
198	if (WIFEXITED(status))
199		return (WEXITSTATUS(status));
200	return (1);
201}
202