xref: /freebsd/crypto/openssh/openbsd-compat/bsd-closefrom.c (revision edf8578117e8844e02c0121147f45e4609b30680)
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  */
63 static void
closefrom_fallback(int lowfd)64 closefrom_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
87 void
closefrom(int lowfd)88 closefrom(int lowfd)
89 {
90     (void) fcntl(lowfd, F_CLOSEM, 0);
91 }
92 #elif defined(HAVE_LIBPROC_H) && defined(HAVE_PROC_PIDINFO)
93 void
closefrom(int lowfd)94 closefrom(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)
122 void
closefrom(int lowfd)123 closefrom(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
152 void
closefrom(int lowfd)153 closefrom(int lowfd)
154 {
155 	closefrom_fallback(lowfd);
156 }
157 #endif /* !HAVE_FCNTL_CLOSEM */
158 #endif /* HAVE_CLOSEFROM */
159