1/*
2 * Copyright (c) 2004-2005 Todd C. Miller <Todd.Miller@courtesan.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16
17#include "includes.h"
18
19#if !defined(HAVE_CLOSEFROM) || defined(BROKEN_CLOSEFROM)
20
21#include <sys/types.h>
22#include <unistd.h>
23#include <stdio.h>
24#ifdef HAVE_FCNTL_H
25# include <fcntl.h>
26#endif
27#include <limits.h>
28#include <stdlib.h>
29#include <stddef.h>
30#include <string.h>
31#ifdef HAVE_DIRENT_H
32# include <dirent.h>
33# define NAMLEN(dirent) strlen((dirent)->d_name)
34#else
35# define dirent direct
36# define NAMLEN(dirent) (dirent)->d_namlen
37# ifdef HAVE_SYS_NDIR_H
38#  include <sys/ndir.h>
39# endif
40# ifdef HAVE_SYS_DIR_H
41#  include <sys/dir.h>
42# endif
43# ifdef HAVE_NDIR_H
44#  include <ndir.h>
45# endif
46#endif
47#if defined(HAVE_LIBPROC_H)
48# include <libproc.h>
49#endif
50
51#ifndef OPEN_MAX
52# define OPEN_MAX	256
53#endif
54
55#if 0
56__unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
57#endif /* lint */
58
59#ifndef HAVE_FCNTL_CLOSEM
60/*
61 * Close all file descriptors greater than or equal to lowfd.
62 */
63static void
64closefrom_fallback(int lowfd)
65{
66	long fd, maxfd;
67
68	/*
69	 * Fall back on sysconf() or getdtablesize().  We avoid checking
70	 * resource limits since it is possible to open a file descriptor
71	 * and then drop the rlimit such that it is below the open fd.
72	 */
73#ifdef HAVE_SYSCONF
74	maxfd = sysconf(_SC_OPEN_MAX);
75#else
76	maxfd = getdtablesize();
77#endif /* HAVE_SYSCONF */
78	if (maxfd < 0)
79		maxfd = OPEN_MAX;
80
81	for (fd = lowfd; fd < maxfd; fd++)
82		(void) close((int) fd);
83}
84#endif /* HAVE_FCNTL_CLOSEM */
85
86#ifdef HAVE_FCNTL_CLOSEM
87void
88closefrom(int lowfd)
89{
90    (void) fcntl(lowfd, F_CLOSEM, 0);
91}
92#elif defined(HAVE_LIBPROC_H) && defined(HAVE_PROC_PIDINFO)
93void
94closefrom(int lowfd)
95{
96	int i, r, sz;
97	pid_t pid = getpid();
98	struct proc_fdinfo *fdinfo_buf = NULL;
99
100	sz = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
101	if (sz == 0)
102		return; /* no fds, really? */
103	else if (sz == -1)
104		goto fallback;
105	if ((fdinfo_buf = malloc(sz)) == NULL)
106		goto fallback;
107	r = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, fdinfo_buf, sz);
108	if (r < 0 || r > sz)
109		goto fallback;
110	for (i = 0; i < r / (int)PROC_PIDLISTFD_SIZE; i++) {
111		if (fdinfo_buf[i].proc_fd >= lowfd)
112			close(fdinfo_buf[i].proc_fd);
113	}
114	free(fdinfo_buf);
115	return;
116 fallback:
117	free(fdinfo_buf);
118	closefrom_fallback(lowfd);
119	return;
120}
121#elif defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
122void
123closefrom(int lowfd)
124{
125    long fd;
126    char fdpath[PATH_MAX], *endp;
127    struct dirent *dent;
128    DIR *dirp;
129    int len;
130
131#ifdef HAVE_CLOSE_RANGE
132	if (close_range(lowfd, INT_MAX, 0) == 0)
133		return;
134#endif
135
136    /* Check for a /proc/$$/fd directory. */
137    len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
138    if (len > 0 && (size_t)len < sizeof(fdpath) && (dirp = opendir(fdpath))) {
139	while ((dent = readdir(dirp)) != NULL) {
140	    fd = strtol(dent->d_name, &endp, 10);
141	    if (dent->d_name != endp && *endp == '\0' &&
142		fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
143		(void) close((int) fd);
144	}
145	(void) closedir(dirp);
146	return;
147    }
148    /* /proc/$$/fd strategy failed, fall back to brute force closure */
149    closefrom_fallback(lowfd);
150}
151#else
152void
153closefrom(int lowfd)
154{
155	closefrom_fallback(lowfd);
156}
157#endif /* !HAVE_FCNTL_CLOSEM */
158#endif /* HAVE_CLOSEFROM */
159