platform.c revision 262566 
1/* $Id: platform.c,v 1.21 2014/01/21 01:59:29 tim Exp $ */
2
3/*
4 * Copyright (c) 2006 Darren Tucker.  All rights reserved.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include "includes.h"
20
21#include <sys/types.h>
22
23#include <stdarg.h>
24#include <unistd.h>
25
26#include "log.h"
27#include "buffer.h"
28#include "servconf.h"
29#include "key.h"
30#include "hostfile.h"
31#include "auth.h"
32#include "auth-pam.h"
33#include "platform.h"
34
35#include "openbsd-compat/openbsd-compat.h"
36
37extern int use_privsep;
38extern ServerOptions options;
39
40void
41platform_pre_listen(void)
42{
43#ifdef LINUX_OOM_ADJUST
44	/* Adjust out-of-memory killer so listening process is not killed */
45	oom_adjust_setup();
46#endif
47}
48
49void
50platform_pre_fork(void)
51{
52#ifdef USE_SOLARIS_PROCESS_CONTRACTS
53	solaris_contract_pre_fork();
54#endif
55}
56
57void
58platform_pre_restart(void)
59{
60#ifdef LINUX_OOM_ADJUST
61	oom_adjust_restore();
62#endif
63}
64
65void
66platform_post_fork_parent(pid_t child_pid)
67{
68#ifdef USE_SOLARIS_PROCESS_CONTRACTS
69	solaris_contract_post_fork_parent(child_pid);
70#endif
71}
72
73void
74platform_post_fork_child(void)
75{
76#ifdef USE_SOLARIS_PROCESS_CONTRACTS
77	solaris_contract_post_fork_child();
78#endif
79#ifdef LINUX_OOM_ADJUST
80	oom_adjust_restore();
81#endif
82}
83
84/* return 1 if we are running with privilege to swap UIDs, 0 otherwise */
85int
86platform_privileged_uidswap(void)
87{
88#ifdef HAVE_CYGWIN
89	/* uid 0 is not special on Cygwin so always try */
90	return 1;
91#else
92	return (getuid() == 0 || geteuid() == 0);
93#endif
94}
95
96/*
97 * This gets called before switching UIDs, and is called even when sshd is
98 * not running as root.
99 */
100void
101platform_setusercontext(struct passwd *pw)
102{
103#ifdef WITH_SELINUX
104	/* Cache selinux status for later use */
105	(void)ssh_selinux_enabled();
106#endif
107
108#ifdef USE_SOLARIS_PROJECTS
109	/* if solaris projects were detected, set the default now */
110	if (getuid() == 0 || geteuid() == 0)
111		solaris_set_default_project(pw);
112#endif
113
114#if defined(HAVE_LOGIN_CAP) && defined (__bsdi__)
115	if (getuid() == 0 || geteuid() == 0)
116		setpgid(0, 0);
117# endif
118
119#if defined(HAVE_LOGIN_CAP) && defined(USE_PAM)
120	/*
121	 * If we have both LOGIN_CAP and PAM, we want to establish creds
122	 * before calling setusercontext (in session.c:do_setusercontext).
123	 */
124	if (getuid() == 0 || geteuid() == 0) {
125		if (options.use_pam) {
126			do_pam_setcred(use_privsep);
127		}
128	}
129# endif /* USE_PAM */
130
131#if !defined(HAVE_LOGIN_CAP) && defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
132	if (getuid() == 0 || geteuid() == 0) {
133		/* Sets login uid for accounting */
134		if (getluid() == -1 && setluid(pw->pw_uid) == -1)
135			error("setluid: %s", strerror(errno));
136	}
137#endif
138}
139
140/*
141 * This gets called after we've established the user's groups, and is only
142 * called if sshd is running as root.
143 */
144void
145platform_setusercontext_post_groups(struct passwd *pw)
146{
147#if !defined(HAVE_LOGIN_CAP) && defined(USE_PAM)
148	/*
149	 * PAM credentials may take the form of supplementary groups.
150	 * These will have been wiped by the above initgroups() call.
151	 * Reestablish them here.
152	 */
153	if (options.use_pam) {
154		do_pam_setcred(use_privsep);
155	}
156#endif /* USE_PAM */
157
158#if !defined(HAVE_LOGIN_CAP) && (defined(WITH_IRIX_PROJECT) || \
159    defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY))
160	irix_setusercontext(pw);
161#endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
162
163#ifdef _AIX
164	aix_usrinfo(pw);
165#endif /* _AIX */
166
167#ifdef HAVE_SETPCRED
168	/*
169	 * If we have a chroot directory, we set all creds except real
170	 * uid which we will need for chroot.  If we don't have a
171	 * chroot directory, we don't override anything.
172	 */
173	{
174		char **creds = NULL, *chroot_creds[] =
175		    { "REAL_USER=root", NULL };
176
177		if (options.chroot_directory != NULL &&
178		    strcasecmp(options.chroot_directory, "none") != 0)
179			creds = chroot_creds;
180
181		if (setpcred(pw->pw_name, creds) == -1)
182			fatal("Failed to set process credentials");
183	}
184#endif /* HAVE_SETPCRED */
185#ifdef WITH_SELINUX
186	ssh_selinux_setup_exec_context(pw->pw_name);
187#endif
188}
189
190char *
191platform_krb5_get_principal_name(const char *pw_name)
192{
193#ifdef USE_AIX_KRB_NAME
194	return aix_krb5_get_principal_name(pw_name);
195#else
196	return NULL;
197#endif
198}
199
200/*
201 * return 1 if the specified uid is a uid that may own a system directory
202 * otherwise 0.
203 */
204int
205platform_sys_dir_uid(uid_t uid)
206{
207	if (uid == 0)
208		return 1;
209#ifdef PLATFORM_SYS_DIR_UID
210	if (uid == PLATFORM_SYS_DIR_UID)
211		return 1;
212#endif
213	return 0;
214}
215