kern_loginclass.c revision 220137 
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: head/sys/kern/kern_loginclass.c 220137 2011-03-29 17:47:25Z trasz $
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: head/sys/kern/kern_loginclass.c 220137 2011-03-29 17:47:25Z trasz $");
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;
72
73static void lc_init(void);
74SYSINIT(loginclass, SI_SUB_CPU, SI_ORDER_FIRST, lc_init, NULL);
75
76void
77loginclass_hold(struct loginclass *lc)
78{
79
80	refcount_acquire(&lc->lc_refcount);
81}
82
83void
84loginclass_free(struct loginclass *lc)
85{
86	int old;
87
88	old = lc->lc_refcount;
89	if (old > 1 && atomic_cmpset_int(&lc->lc_refcount, old, old - 1))
90		return;
91
92	mtx_lock(&loginclasses_lock);
93	if (refcount_release(&lc->lc_refcount)) {
94		racct_destroy(&lc->lc_racct);
95		LIST_REMOVE(lc, lc_next);
96		mtx_unlock(&loginclasses_lock);
97		free(lc, M_LOGINCLASS);
98
99		return;
100	}
101	mtx_unlock(&loginclasses_lock);
102}
103
104/*
105 * Return loginclass structure with a corresponding name.  Not
106 * performance critical, as it's used mainly by setloginclass(2),
107 * which happens once per login session.  Caller has to use
108 * loginclass_free() on the returned value when it's no longer
109 * needed.
110 */
111struct loginclass *
112loginclass_find(const char *name)
113{
114	struct loginclass *lc, *newlc;
115
116	if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
117		return (NULL);
118
119	newlc = malloc(sizeof(*newlc), M_LOGINCLASS, M_ZERO | M_WAITOK);
120	racct_create(&newlc->lc_racct);
121
122	mtx_lock(&loginclasses_lock);
123	LIST_FOREACH(lc, &loginclasses, lc_next) {
124		if (strcmp(name, lc->lc_name) != 0)
125			continue;
126
127		/* Found loginclass with a matching name? */
128		loginclass_hold(lc);
129		mtx_unlock(&loginclasses_lock);
130		racct_destroy(&newlc->lc_racct);
131		free(newlc, M_LOGINCLASS);
132		return (lc);
133	}
134
135	/* Add new loginclass. */
136	strcpy(newlc->lc_name, name);
137	refcount_init(&newlc->lc_refcount, 1);
138	LIST_INSERT_HEAD(&loginclasses, newlc, lc_next);
139	mtx_unlock(&loginclasses_lock);
140
141	return (newlc);
142}
143
144/*
145 * Get login class name.
146 */
147#ifndef _SYS_SYSPROTO_H_
148struct getloginclass_args {
149	char	*namebuf;
150	size_t	namelen;
151};
152#endif
153/* ARGSUSED */
154int
155getloginclass(struct thread *td, struct getloginclass_args *uap)
156{
157	int error = 0;
158	size_t lcnamelen;
159	struct proc *p;
160	struct loginclass *lc;
161
162	p = td->td_proc;
163	PROC_LOCK(p);
164	lc = p->p_ucred->cr_loginclass;
165	loginclass_hold(lc);
166	PROC_UNLOCK(p);
167
168	lcnamelen = strlen(lc->lc_name) + 1;
169	if (lcnamelen > uap->namelen)
170		error = ERANGE;
171	if (error == 0)
172		error = copyout(lc->lc_name, uap->namebuf, lcnamelen);
173	loginclass_free(lc);
174	return (error);
175}
176
177/*
178 * Set login class name.
179 */
180#ifndef _SYS_SYSPROTO_H_
181struct setloginclass_args {
182	const char	*namebuf;
183};
184#endif
185/* ARGSUSED */
186int
187setloginclass(struct thread *td, struct setloginclass_args *uap)
188{
189	struct proc *p = td->td_proc;
190	int error;
191	char lcname[MAXLOGNAME];
192	struct loginclass *newlc;
193	struct ucred *newcred, *oldcred;
194
195	error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
196	if (error != 0)
197		return (error);
198	error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
199	if (error != 0)
200		return (error);
201
202	newlc = loginclass_find(lcname);
203	if (newlc == NULL)
204		return (EINVAL);
205	newcred = crget();
206
207	PROC_LOCK(p);
208	oldcred = crcopysafe(p, newcred);
209	newcred->cr_loginclass = newlc;
210	p->p_ucred = newcred;
211	PROC_UNLOCK(p);
212#ifdef RACCT
213	racct_proc_ucred_changed(p, oldcred, newcred);
214#endif
215	loginclass_free(oldcred->cr_loginclass);
216	crfree(oldcred);
217
218	return (0);
219}
220
221void
222loginclass_racct_foreach(void (*callback)(struct racct *racct,
223    void *arg2, void *arg3), void *arg2, void *arg3)
224{
225	struct loginclass *lc;
226
227	mtx_lock(&loginclasses_lock);
228	LIST_FOREACH(lc, &loginclasses, lc_next)
229		(callback)(lc->lc_racct, arg2, arg3);
230	mtx_unlock(&loginclasses_lock);
231}
232
233static void
234lc_init(void)
235{
236
237	mtx_init(&loginclasses_lock, "loginclasses lock", NULL, MTX_DEF);
238}
239