popen.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1988, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software written by Ken Arnold and
8 * published in UNIX Review, Vol. 6, No. 8.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#ifndef lint
36#if 0
37static char sccsid[] = "@(#)popen.c	8.3 (Berkeley) 4/6/94";
38#endif
39#endif /* not lint */
40
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: stable/11/libexec/ftpd/popen.c 330897 2018-03-14 03:19:51Z eadler $");
43
44#include <sys/types.h>
45#include <sys/wait.h>
46#include <netinet/in.h>
47
48#include <errno.h>
49#include <glob.h>
50#include <signal.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <unistd.h>
55
56#include "extern.h"
57#include "pathnames.h"
58#include <syslog.h>
59#include <time.h>
60
61#define	MAXUSRARGS	100
62#define	MAXGLOBARGS	1000
63
64/*
65 * Special version of popen which avoids call to shell.  This ensures no one
66 * may create a pipe to a hidden program as a side effect of a list or dir
67 * command.
68 */
69static int *pids;
70static int fds;
71
72FILE *
73ftpd_popen(char *program, char *type)
74{
75	char *cp;
76	FILE *iop;
77	int argc, gargc, pdes[2], pid;
78	char **pop, *argv[MAXUSRARGS], *gargv[MAXGLOBARGS];
79
80	if (((*type != 'r') && (*type != 'w')) || type[1])
81		return (NULL);
82
83	if (!pids) {
84		if ((fds = getdtablesize()) <= 0)
85			return (NULL);
86		if ((pids = calloc(fds, sizeof(int))) == NULL)
87			return (NULL);
88	}
89	if (pipe(pdes) < 0)
90		return (NULL);
91
92	/* break up string into pieces */
93	for (argc = 0, cp = program; argc < MAXUSRARGS; cp = NULL) {
94		if (!(argv[argc++] = strtok(cp, " \t\n")))
95			break;
96	}
97	argv[argc - 1] = NULL;
98
99	/* glob each piece */
100	gargv[0] = argv[0];
101	for (gargc = argc = 1; argv[argc] && gargc < (MAXGLOBARGS-1); argc++) {
102		glob_t gl;
103		int flags = GLOB_BRACE|GLOB_NOCHECK|GLOB_TILDE;
104
105		memset(&gl, 0, sizeof(gl));
106		gl.gl_matchc = MAXGLOBARGS;
107		flags |= GLOB_LIMIT;
108		if (glob(argv[argc], flags, NULL, &gl))
109			gargv[gargc++] = strdup(argv[argc]);
110		else if (gl.gl_pathc > 0) {
111			for (pop = gl.gl_pathv; *pop && gargc < (MAXGLOBARGS-1);
112			     pop++)
113				gargv[gargc++] = strdup(*pop);
114		}
115		globfree(&gl);
116	}
117	gargv[gargc] = NULL;
118
119	iop = NULL;
120	fflush(NULL);
121	pid = (strcmp(gargv[0], _PATH_LS) == 0) ? fork() : vfork();
122	switch(pid) {
123	case -1:			/* error */
124		(void)close(pdes[0]);
125		(void)close(pdes[1]);
126		goto pfree;
127		/* NOTREACHED */
128	case 0:				/* child */
129		if (*type == 'r') {
130			if (pdes[1] != STDOUT_FILENO) {
131				dup2(pdes[1], STDOUT_FILENO);
132				(void)close(pdes[1]);
133			}
134			dup2(STDOUT_FILENO, STDERR_FILENO); /* stderr too! */
135			(void)close(pdes[0]);
136		} else {
137			if (pdes[0] != STDIN_FILENO) {
138				dup2(pdes[0], STDIN_FILENO);
139				(void)close(pdes[0]);
140			}
141			(void)close(pdes[1]);
142		}
143		/* Drop privileges before proceeding */
144		if (getuid() != geteuid() && setuid(geteuid()) < 0)
145			_exit(1);
146		if (strcmp(gargv[0], _PATH_LS) == 0) {
147			/* Reset getopt for ls_main() */
148			optreset = optind = optopt = 1;
149			/* Close syslogging to remove pwd.db missing msgs */
150			closelog();
151			/* Trigger to sense new /etc/localtime after chroot */
152			if (getenv("TZ") == NULL) {
153				setenv("TZ", "", 0);
154				tzset();
155				unsetenv("TZ");
156				tzset();
157			}
158			exit(ls_main(gargc, gargv));
159		}
160		execv(gargv[0], gargv);
161		_exit(1);
162	}
163	/* parent; assume fdopen can't fail...  */
164	if (*type == 'r') {
165		iop = fdopen(pdes[0], type);
166		(void)close(pdes[1]);
167	} else {
168		iop = fdopen(pdes[1], type);
169		(void)close(pdes[0]);
170	}
171	pids[fileno(iop)] = pid;
172
173pfree:	for (argc = 1; gargv[argc] != NULL; argc++)
174		free(gargv[argc]);
175
176	return (iop);
177}
178
179int
180ftpd_pclose(FILE *iop)
181{
182	int fdes, omask, status;
183	pid_t pid;
184
185	/*
186	 * pclose returns -1 if stream is not associated with a
187	 * `popened' command, or, if already `pclosed'.
188	 */
189	if (pids == NULL || pids[fdes = fileno(iop)] == 0)
190		return (-1);
191	(void)fclose(iop);
192	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
193	while ((pid = waitpid(pids[fdes], &status, 0)) < 0 && errno == EINTR)
194		continue;
195	(void)sigsetmask(omask);
196	pids[fdes] = 0;
197	if (pid < 0)
198		return (pid);
199	if (WIFEXITED(status))
200		return (WEXITSTATUS(status));
201	return (1);
202}
203