bsd-cygwin_util.c revision 113908 
1/*
2 * cygwin_util.c
3 *
4 * Copyright (c) 2000, 2001, Corinna Vinschen <vinschen@cygnus.com>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * Created: Sat Sep 02 12:17:00 2000 cv
27 *
28 * This file contains functions for forcing opened file descriptors to
29 * binary mode on Windows systems.
30 */
31
32#include "includes.h"
33
34RCSID("$Id: bsd-cygwin_util.c,v 1.9 2002/11/09 15:59:29 mouring Exp $");
35
36#ifdef HAVE_CYGWIN
37
38#include <fcntl.h>
39#include <stdlib.h>
40#include <sys/utsname.h>
41#include <sys/vfs.h>
42#include <windows.h>
43#define is_winnt       (GetVersion() < 0x80000000)
44
45#define ntsec_on(c)	((c) && strstr((c),"ntsec") && !strstr((c),"nontsec"))
46#define ntsec_off(c)	((c) && strstr((c),"nontsec"))
47#define ntea_on(c)	((c) && strstr((c),"ntea") && !strstr((c),"nontea"))
48
49#if defined(open) && open == binary_open
50# undef open
51#endif
52#if defined(pipe) && open == binary_pipe
53# undef pipe
54#endif
55
56int binary_open(const char *filename, int flags, ...)
57{
58	va_list ap;
59	mode_t mode;
60
61	va_start(ap, flags);
62	mode = va_arg(ap, mode_t);
63	va_end(ap);
64	return open(filename, flags | O_BINARY, mode);
65}
66
67int binary_pipe(int fd[2])
68{
69	int ret = pipe(fd);
70
71	if (!ret) {
72		setmode (fd[0], O_BINARY);
73		setmode (fd[1], O_BINARY);
74	}
75	return ret;
76}
77
78#define HAS_CREATE_TOKEN 1
79#define HAS_NTSEC_BY_DEFAULT 2
80
81static int has_capability(int what)
82{
83	/* has_capability() basically calls uname() and checks if
84	   specific capabilities of Cygwin can be evaluated from that.
85	   This simplifies the calling functions which only have to ask
86	   for a capability using has_capability() instead of having
87	   to figure that out by themselves. */
88	static int inited;
89	static int has_create_token;
90	static int has_ntsec_by_default;
91
92	if (!inited) {
93		struct utsname uts;
94		char *c;
95
96		if (!uname(&uts)) {
97			int major_high = 0;
98			int major_low = 0;
99			int minor = 0;
100			int api_major_version = 0;
101			int api_minor_version = 0;
102			char *c;
103
104			sscanf(uts.release, "%d.%d.%d", &major_high,
105			       &major_low, &minor);
106			c = strchr(uts.release, '(');
107			if (c)
108				sscanf(c + 1, "%d.%d", &api_major_version,
109				       &api_minor_version);
110			if (major_high > 1 ||
111			    (major_high == 1 && (major_low > 3 ||
112			     (major_low == 3 && minor >= 2))))
113				has_create_token = 1;
114			if (api_major_version > 0 || api_minor_version >= 56)
115				has_ntsec_by_default = 1;
116			inited = 1;
117		}
118	}
119	switch (what) {
120	case HAS_CREATE_TOKEN:
121		return has_create_token;
122	case HAS_NTSEC_BY_DEFAULT:
123		return has_ntsec_by_default;
124	}
125	return 0;
126}
127
128int check_nt_auth(int pwd_authenticated, struct passwd *pw)
129{
130	/*
131	* The only authentication which is able to change the user
132	* context on NT systems is the password authentication. So
133	* we deny all requsts for changing the user context if another
134	* authentication method is used.
135	*
136	* This doesn't apply to Cygwin versions >= 1.3.2 anymore which
137	* uses the undocumented NtCreateToken() call to create a user
138	* token if the process has the appropriate privileges and if
139	* CYGWIN ntsec setting is on.
140	*/
141	static int has_create_token = -1;
142
143	if (pw == NULL)
144		return 0;
145	if (is_winnt) {
146		if (has_create_token < 0) {
147			char *cygwin = getenv("CYGWIN");
148
149			has_create_token = 0;
150			if (has_capability(HAS_CREATE_TOKEN) &&
151			    (ntsec_on(cygwin) ||
152			     (has_capability(HAS_NTSEC_BY_DEFAULT) &&
153			      !ntsec_off(cygwin))))
154				has_create_token = 1;
155		}
156		if (has_create_token < 1 &&
157		    !pwd_authenticated && geteuid() != pw->pw_uid)
158			return 0;
159	}
160	return 1;
161}
162
163int check_ntsec(const char *filename)
164{
165	char *cygwin;
166	int allow_ntea = 0;
167	int allow_ntsec = 0;
168	struct statfs fsstat;
169
170	/* Windows 95/98/ME don't support file system security at all. */
171	if (!is_winnt)
172		return 0;
173
174	/* Evaluate current CYGWIN settings. */
175	cygwin = getenv("CYGWIN");
176	allow_ntea = ntea_on(cygwin);
177	allow_ntsec = ntsec_on(cygwin) ||
178		      (has_capability(HAS_NTSEC_BY_DEFAULT) &&
179		       !ntsec_off(cygwin));
180
181	/*
182	 * `ntea' is an emulation of POSIX attributes. It doesn't support
183	 * real file level security as ntsec on NTFS file systems does
184	 * but it supports FAT filesystems. `ntea' is minimum requirement
185	 * for security checks.
186	 */
187	if (allow_ntea)
188		return 1;
189
190	/*
191	 * Retrieve file system flags. In Cygwin, file system flags are
192	 * copied to f_type which has no meaning in Win32 itself.
193	 */
194	if (statfs(filename, &fsstat))
195		return 1;
196
197	/*
198	 * Only file systems supporting ACLs are able to set permissions.
199	 * `ntsec' is the setting in Cygwin which switches using of NTFS
200	 * ACLs to support POSIX permissions on files.
201	 */
202	if (fsstat.f_type & FS_PERSISTENT_ACLS)
203		return allow_ntsec;
204
205	return 0;
206}
207
208void register_9x_service(void)
209{
210        HINSTANCE kerneldll;
211        DWORD (*RegisterServiceProcess)(DWORD, DWORD);
212
213	/* The service register mechanism in 9x/Me is pretty different from
214	 * NT/2K/XP.  In NT/2K/XP we're using a special service starter
215	 * application to register and control sshd as service.  This method
216	 * doesn't play nicely with 9x/Me.  For that reason we register here
217	 * as service when running under 9x/Me.  This function is only called
218	 * by the child sshd when it's going to daemonize.
219	 */
220	if (is_winnt)
221		return;
222	if (! (kerneldll = LoadLibrary("KERNEL32.DLL")))
223		return;
224	if (! (RegisterServiceProcess = (DWORD (*)(DWORD, DWORD))
225			  GetProcAddress(kerneldll, "RegisterServiceProcess")))
226		return;
227	RegisterServiceProcess(0, 1);
228}
229
230#endif /* HAVE_CYGWIN */
231