kern_loginclass.c revision 302229 
1/*-
2 * Copyright (c) 2011 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Edward Tomasz Napierala under sponsorship
6 * from the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: stable/10/sys/kern/kern_loginclass.c 302229 2016-06-27 21:25:01Z bdrewery $
30 */
31
32/*
33 * Processes may set login class name using setloginclass(2).  This
34 * is usually done through call to setusercontext(3), by programs
35 * such as login(1), based on information from master.passwd(5).  Kernel
36 * uses this information to enforce per-class resource limits.  Current
37 * login class can be determined using id(1).  Login class is inherited
38 * from the parent process during fork(2).  If not set, it defaults
39 * to "default".
40 *
41 * Code in this file implements setloginclass(2) and getloginclass(2)
42 * system calls, and maintains class name storage and retrieval.
43 */
44
45#include <sys/cdefs.h>
46__FBSDID("$FreeBSD: stable/10/sys/kern/kern_loginclass.c 302229 2016-06-27 21:25:01Z bdrewery $");
47
48#include <sys/param.h>
49#include <sys/eventhandler.h>
50#include <sys/kernel.h>
51#include <sys/lock.h>
52#include <sys/loginclass.h>
53#include <sys/malloc.h>
54#include <sys/mutex.h>
55#include <sys/types.h>
56#include <sys/priv.h>
57#include <sys/proc.h>
58#include <sys/queue.h>
59#include <sys/racct.h>
60#include <sys/refcount.h>
61#include <sys/sysproto.h>
62#include <sys/systm.h>
63
64static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
65
66LIST_HEAD(, loginclass)	loginclasses;
67
68/*
69 * Lock protecting loginclasses list.
70 */
71static struct mtx loginclasses_lock;
72MTX_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock", MTX_DEF);
73
74void
75loginclass_hold(struct loginclass *lc)
76{
77
78	refcount_acquire(&lc->lc_refcount);
79}
80
81void
82loginclass_free(struct loginclass *lc)
83{
84	int old;
85
86	old = lc->lc_refcount;
87	if (old > 1 && atomic_cmpset_int(&lc->lc_refcount, old, old - 1))
88		return;
89
90	mtx_lock(&loginclasses_lock);
91	if (refcount_release(&lc->lc_refcount)) {
92		racct_destroy(&lc->lc_racct);
93		LIST_REMOVE(lc, lc_next);
94		mtx_unlock(&loginclasses_lock);
95		free(lc, M_LOGINCLASS);
96
97		return;
98	}
99	mtx_unlock(&loginclasses_lock);
100}
101
102/*
103 * Return loginclass structure with a corresponding name.  Not
104 * performance critical, as it's used mainly by setloginclass(2),
105 * which happens once per login session.  Caller has to use
106 * loginclass_free() on the returned value when it's no longer
107 * needed.
108 */
109struct loginclass *
110loginclass_find(const char *name)
111{
112	struct loginclass *lc, *newlc;
113
114	if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
115		return (NULL);
116
117	newlc = malloc(sizeof(*newlc), M_LOGINCLASS, M_ZERO | M_WAITOK);
118	racct_create(&newlc->lc_racct);
119
120	mtx_lock(&loginclasses_lock);
121	LIST_FOREACH(lc, &loginclasses, lc_next) {
122		if (strcmp(name, lc->lc_name) != 0)
123			continue;
124
125		/* Found loginclass with a matching name? */
126		loginclass_hold(lc);
127		mtx_unlock(&loginclasses_lock);
128		racct_destroy(&newlc->lc_racct);
129		free(newlc, M_LOGINCLASS);
130		return (lc);
131	}
132
133	/* Add new loginclass. */
134	strcpy(newlc->lc_name, name);
135	refcount_init(&newlc->lc_refcount, 1);
136	LIST_INSERT_HEAD(&loginclasses, newlc, lc_next);
137	mtx_unlock(&loginclasses_lock);
138
139	return (newlc);
140}
141
142/*
143 * Get login class name.
144 */
145#ifndef _SYS_SYSPROTO_H_
146struct getloginclass_args {
147	char	*namebuf;
148	size_t	namelen;
149};
150#endif
151/* ARGSUSED */
152int
153sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
154{
155	int error = 0;
156	size_t lcnamelen;
157	struct proc *p;
158	struct loginclass *lc;
159
160	p = td->td_proc;
161	PROC_LOCK(p);
162	lc = p->p_ucred->cr_loginclass;
163	loginclass_hold(lc);
164	PROC_UNLOCK(p);
165
166	lcnamelen = strlen(lc->lc_name) + 1;
167	if (lcnamelen > uap->namelen)
168		error = ERANGE;
169	if (error == 0)
170		error = copyout(lc->lc_name, uap->namebuf, lcnamelen);
171	loginclass_free(lc);
172	return (error);
173}
174
175/*
176 * Set login class name.
177 */
178#ifndef _SYS_SYSPROTO_H_
179struct setloginclass_args {
180	const char	*namebuf;
181};
182#endif
183/* ARGSUSED */
184int
185sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
186{
187	struct proc *p = td->td_proc;
188	int error;
189	char lcname[MAXLOGNAME];
190	struct loginclass *newlc;
191	struct ucred *newcred, *oldcred;
192
193	error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
194	if (error != 0)
195		return (error);
196	error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
197	if (error != 0)
198		return (error);
199
200	newlc = loginclass_find(lcname);
201	if (newlc == NULL)
202		return (EINVAL);
203	newcred = crget();
204
205	PROC_LOCK(p);
206	oldcred = crcopysafe(p, newcred);
207	newcred->cr_loginclass = newlc;
208	proc_set_cred(p, newcred);
209	PROC_UNLOCK(p);
210#ifdef RACCT
211	racct_proc_ucred_changed(p, oldcred, newcred);
212#endif
213	loginclass_free(oldcred->cr_loginclass);
214	crfree(oldcred);
215
216	return (0);
217}
218
219void
220loginclass_racct_foreach(void (*callback)(struct racct *racct,
221    void *arg2, void *arg3), void *arg2, void *arg3)
222{
223	struct loginclass *lc;
224
225	mtx_lock(&loginclasses_lock);
226	LIST_FOREACH(lc, &loginclasses, lc_next)
227		(callback)(lc->lc_racct, arg2, arg3);
228	mtx_unlock(&loginclasses_lock);
229}
230