1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 The FreeBSD Foundation
5 *
6 * This software was developed by Edward Tomasz Napierala under sponsorship
7 * from the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31/*
32 * Processes may set login class name using setloginclass(2).  This
33 * is usually done through call to setusercontext(3), by programs
34 * such as login(1), based on information from master.passwd(5).  Kernel
35 * uses this information to enforce per-class resource limits.  Current
36 * login class can be determined using id(1).  Login class is inherited
37 * from the parent process during fork(2).  If not set, it defaults
38 * to "default".
39 *
40 * Code in this file implements setloginclass(2) and getloginclass(2)
41 * system calls, and maintains class name storage and retrieval.
42 */
43
44#include <sys/param.h>
45#include <sys/eventhandler.h>
46#include <sys/kernel.h>
47#include <sys/lock.h>
48#include <sys/loginclass.h>
49#include <sys/malloc.h>
50#include <sys/types.h>
51#include <sys/priv.h>
52#include <sys/proc.h>
53#include <sys/queue.h>
54#include <sys/racct.h>
55#include <sys/rctl.h>
56#include <sys/refcount.h>
57#include <sys/rwlock.h>
58#include <sys/sysproto.h>
59#include <sys/systm.h>
60
61static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
62
63LIST_HEAD(, loginclass)	loginclasses;
64
65/*
66 * Lock protecting loginclasses list.
67 */
68static struct rwlock loginclasses_lock;
69RW_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock");
70
71void
72loginclass_hold(struct loginclass *lc)
73{
74
75	refcount_acquire(&lc->lc_refcount);
76}
77
78void
79loginclass_free(struct loginclass *lc)
80{
81
82	if (refcount_release_if_not_last(&lc->lc_refcount))
83		return;
84
85	rw_wlock(&loginclasses_lock);
86	if (!refcount_release(&lc->lc_refcount)) {
87		rw_wunlock(&loginclasses_lock);
88		return;
89	}
90
91	racct_destroy(&lc->lc_racct);
92	LIST_REMOVE(lc, lc_next);
93	rw_wunlock(&loginclasses_lock);
94
95	free(lc, M_LOGINCLASS);
96}
97
98/*
99 * Look up a loginclass struct for the parameter name.
100 * loginclasses_lock must be locked.
101 * Increase refcount on loginclass struct returned.
102 */
103static struct loginclass *
104loginclass_lookup(const char *name)
105{
106	struct loginclass *lc;
107
108	rw_assert(&loginclasses_lock, RA_LOCKED);
109	LIST_FOREACH(lc, &loginclasses, lc_next)
110		if (strcmp(name, lc->lc_name) == 0) {
111			loginclass_hold(lc);
112			break;
113		}
114
115	return (lc);
116}
117
118/*
119 * Return loginclass structure with a corresponding name.  Not
120 * performance critical, as it's used mainly by setloginclass(2),
121 * which happens once per login session.  Caller has to use
122 * loginclass_free() on the returned value when it's no longer
123 * needed.
124 */
125struct loginclass *
126loginclass_find(const char *name)
127{
128	struct loginclass *lc, *new_lc;
129
130	if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
131		return (NULL);
132
133	lc = curthread->td_ucred->cr_loginclass;
134	if (strcmp(name, lc->lc_name) == 0) {
135		loginclass_hold(lc);
136		return (lc);
137	}
138
139	rw_rlock(&loginclasses_lock);
140	lc = loginclass_lookup(name);
141	rw_runlock(&loginclasses_lock);
142	if (lc != NULL)
143		return (lc);
144
145	new_lc = malloc(sizeof(*new_lc), M_LOGINCLASS, M_ZERO | M_WAITOK);
146	racct_create(&new_lc->lc_racct);
147	refcount_init(&new_lc->lc_refcount, 1);
148	strcpy(new_lc->lc_name, name);
149
150	rw_wlock(&loginclasses_lock);
151	/*
152	 * There's a chance someone created our loginclass while we
153	 * were in malloc and not holding the lock, so we have to
154	 * make sure we don't insert a duplicate loginclass.
155	 */
156	if ((lc = loginclass_lookup(name)) == NULL) {
157		LIST_INSERT_HEAD(&loginclasses, new_lc, lc_next);
158		rw_wunlock(&loginclasses_lock);
159		lc = new_lc;
160	} else {
161		rw_wunlock(&loginclasses_lock);
162		racct_destroy(&new_lc->lc_racct);
163		free(new_lc, M_LOGINCLASS);
164	}
165
166	return (lc);
167}
168
169/*
170 * Get login class name.
171 */
172#ifndef _SYS_SYSPROTO_H_
173struct getloginclass_args {
174	char	*namebuf;
175	size_t	namelen;
176};
177#endif
178/* ARGSUSED */
179int
180sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
181{
182	struct loginclass *lc;
183	size_t lcnamelen;
184
185	lc = td->td_ucred->cr_loginclass;
186	lcnamelen = strlen(lc->lc_name) + 1;
187	if (lcnamelen > uap->namelen)
188		return (ERANGE);
189	return (copyout(lc->lc_name, uap->namebuf, lcnamelen));
190}
191
192/*
193 * Set login class name.
194 */
195#ifndef _SYS_SYSPROTO_H_
196struct setloginclass_args {
197	const char	*namebuf;
198};
199#endif
200/* ARGSUSED */
201int
202sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
203{
204	struct proc *p = td->td_proc;
205	int error;
206	char lcname[MAXLOGNAME];
207	struct loginclass *newlc;
208	struct ucred *newcred, *oldcred;
209
210	error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
211	if (error != 0)
212		return (error);
213	error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
214	if (error != 0)
215		return (error);
216
217	newlc = loginclass_find(lcname);
218	if (newlc == NULL)
219		return (EINVAL);
220	newcred = crget();
221
222	PROC_LOCK(p);
223	oldcred = crcopysafe(p, newcred);
224	newcred->cr_loginclass = newlc;
225	proc_set_cred(p, newcred);
226#ifdef RACCT
227	racct_proc_ucred_changed(p, oldcred, newcred);
228	crhold(newcred);
229#endif
230	PROC_UNLOCK(p);
231#ifdef RCTL
232	rctl_proc_ucred_changed(p, newcred);
233	crfree(newcred);
234#endif
235	loginclass_free(oldcred->cr_loginclass);
236	crfree(oldcred);
237
238	return (0);
239}
240
241void
242loginclass_racct_foreach(void (*callback)(struct racct *racct,
243    void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
244    void *arg2, void *arg3)
245{
246	struct loginclass *lc;
247
248	rw_rlock(&loginclasses_lock);
249	if (pre != NULL)
250		(pre)();
251	LIST_FOREACH(lc, &loginclasses, lc_next)
252		(callback)(lc->lc_racct, arg2, arg3);
253	if (post != NULL)
254		(post)();
255	rw_runlock(&loginclasses_lock);
256}
257