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 #ifndef HAVE_CLOSEFROM
20 
21 #include <sys/types.h>
22 #include <sys/param.h>
23 #include <unistd.h>
24 #include <stdio.h>
25 #ifdef HAVE_FCNTL_H
26 # include <fcntl.h>
27 #endif
28 #include <limits.h>
29 #include <stdlib.h>
30 #include <stddef.h>
31 #include <string.h>
32 #include <unistd.h>
33 #ifdef HAVE_DIRENT_H
34 # include <dirent.h>
35 # define NAMLEN(dirent) strlen((dirent)->d_name)
36 #else
37 # define dirent direct
38 # define NAMLEN(dirent) (dirent)->d_namlen
39 # ifdef HAVE_SYS_NDIR_H
40 #  include <sys/ndir.h>
41 # endif
42 # ifdef HAVE_SYS_DIR_H
43 #  include <sys/dir.h>
44 # endif
45 # ifdef HAVE_NDIR_H
46 #  include <ndir.h>
47 # endif
48 #endif
49 #if defined(HAVE_LIBPROC_H)
50 # include <libproc.h>
51 #endif
52 
53 #ifndef OPEN_MAX
54 # define OPEN_MAX	256
55 #endif
56 
57 #if 0
58 __unused static const char rcsid[] = "$Sudo: closefrom.c,v 1.11 2006/08/17 15:26:54 millert Exp $";
59 #endif /* lint */
60 
61 #ifndef HAVE_FCNTL_CLOSEM
62 /*
63  * Close all file descriptors greater than or equal to lowfd.
64  */
65 static void
66 closefrom_fallback(int lowfd)
67 {
68 	long fd, maxfd;
69 
70 	/*
71 	 * Fall back on sysconf() or getdtablesize().  We avoid checking
72 	 * resource limits since it is possible to open a file descriptor
73 	 * and then drop the rlimit such that it is below the open fd.
74 	 */
75 #ifdef HAVE_SYSCONF
76 	maxfd = sysconf(_SC_OPEN_MAX);
77 #else
78 	maxfd = getdtablesize();
79 #endif /* HAVE_SYSCONF */
80 	if (maxfd < 0)
81 		maxfd = OPEN_MAX;
82 
83 	for (fd = lowfd; fd < maxfd; fd++)
84 		(void) close((int) fd);
85 }
86 #endif /* HAVE_FCNTL_CLOSEM */
87 
88 #ifdef HAVE_FCNTL_CLOSEM
89 void
90 closefrom(int lowfd)
91 {
92     (void) fcntl(lowfd, F_CLOSEM, 0);
93 }
94 #elif defined(HAVE_LIBPROC_H) && defined(HAVE_PROC_PIDINFO)
95 void
96 closefrom(int lowfd)
97 {
98 	int i, r, sz;
99 	pid_t pid = getpid();
100 	struct proc_fdinfo *fdinfo_buf = NULL;
101 
102 	sz = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
103 	if (sz == 0)
104 		return; /* no fds, really? */
105 	else if (sz == -1)
106 		goto fallback;
107 	if ((fdinfo_buf = malloc(sz)) == NULL)
108 		goto fallback;
109 	r = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, fdinfo_buf, sz);
110 	if (r < 0 || r >= sz)
111 		goto fallback;
112 	for (i = 0; i < sz / (int)PROC_PIDLISTFD_SIZE; i++) {
113 		if (fdinfo_buf[i].proc_fd >= lowfd)
114 			close(fdinfo_buf[i].proc_fd);
115 	}
116 	free(fdinfo_buf);
117 	return;
118  fallback:
119 	free(fdinfo_buf);
120 	closefrom_fallback(lowfd);
121 	return;
122 }
123 #elif defined(HAVE_DIRFD) && defined(HAVE_PROC_PID)
124 void
125 closefrom(int lowfd)
126 {
127     long fd;
128     char fdpath[PATH_MAX], *endp;
129     struct dirent *dent;
130     DIR *dirp;
131     int len;
132 
133     /* Check for a /proc/$$/fd directory. */
134     len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
135     if (len > 0 && (size_t)len < sizeof(fdpath) && (dirp = opendir(fdpath))) {
136 	while ((dent = readdir(dirp)) != NULL) {
137 	    fd = strtol(dent->d_name, &endp, 10);
138 	    if (dent->d_name != endp && *endp == '\0' &&
139 		fd >= 0 && fd < INT_MAX && fd >= lowfd && fd != dirfd(dirp))
140 		(void) close((int) fd);
141 	}
142 	(void) closedir(dirp);
143 	return;
144     }
145     /* /proc/$$/fd strategy failed, fall back to brute force closure */
146     closefrom_fallback(lowfd);
147 }
148 #else
149 void
150 closefrom(int lowfd)
151 {
152 	closefrom_fallback(lowfd);
153 }
154 #endif /* !HAVE_FCNTL_CLOSEM */
155 #endif /* HAVE_CLOSEFROM */
156