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: releng/11.1/sys/kern/kern_loginclass.c 290857 2015-11-15 12:10:51Z 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: releng/11.1/sys/kern/kern_loginclass.c 290857 2015-11-15 12:10:51Z 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/types.h>
55 #include <sys/priv.h>
56 #include <sys/proc.h>
57 #include <sys/queue.h>
58 #include <sys/racct.h>
59 #include <sys/refcount.h>
60 #include <sys/rwlock.h>
61 #include <sys/sysproto.h>
62 #include <sys/systm.h>
63
64 static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
65
66 LIST_HEAD(, loginclass) loginclasses;
67
68 /*
69 * Lock protecting loginclasses list.
70 */
71 static struct rwlock loginclasses_lock;
72 RW_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock");
73
74 void
75 loginclass_hold(struct loginclass *lc)
76 {
77
78 refcount_acquire(&lc->lc_refcount);
79 }
80
81 void
82 loginclass_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 rw_wlock(&loginclasses_lock);
91 if (!refcount_release(&lc->lc_refcount)) {
92 rw_wunlock(&loginclasses_lock);
93 return;
94 }
95
96 racct_destroy(&lc->lc_racct);
97 LIST_REMOVE(lc, lc_next);
98 rw_wunlock(&loginclasses_lock);
99
100 free(lc, M_LOGINCLASS);
101 }
102
103 /*
104 * Look up a loginclass struct for the parameter name.
105 * loginclasses_lock must be locked.
106 * Increase refcount on loginclass struct returned.
107 */
108 static struct loginclass *
109 loginclass_lookup(const char *name)
110 {
111 struct loginclass *lc;
112
113 rw_assert(&loginclasses_lock, RA_LOCKED);
114 LIST_FOREACH(lc, &loginclasses, lc_next)
115 if (strcmp(name, lc->lc_name) == 0) {
116 loginclass_hold(lc);
117 break;
118 }
119
120 return (lc);
121 }
122
123 /*
124 * Return loginclass structure with a corresponding name. Not
125 * performance critical, as it's used mainly by setloginclass(2),
126 * which happens once per login session. Caller has to use
127 * loginclass_free() on the returned value when it's no longer
128 * needed.
129 */
130 struct loginclass *
131 loginclass_find(const char *name)
132 {
133 struct loginclass *lc, *new_lc;
134
135 if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
136 return (NULL);
137
138 rw_rlock(&loginclasses_lock);
139 lc = loginclass_lookup(name);
140 rw_runlock(&loginclasses_lock);
141 if (lc != NULL)
142 return (lc);
143
144 new_lc = malloc(sizeof(*new_lc), M_LOGINCLASS, M_ZERO | M_WAITOK);
145 racct_create(&new_lc->lc_racct);
146 refcount_init(&new_lc->lc_refcount, 1);
147 strcpy(new_lc->lc_name, name);
148
149 rw_wlock(&loginclasses_lock);
150 /*
151 * There's a chance someone created our loginclass while we
152 * were in malloc and not holding the lock, so we have to
153 * make sure we don't insert a duplicate loginclass.
154 */
155 if ((lc = loginclass_lookup(name)) == NULL) {
156 LIST_INSERT_HEAD(&loginclasses, new_lc, lc_next);
157 rw_wunlock(&loginclasses_lock);
158 lc = new_lc;
159 } else {
160 rw_wunlock(&loginclasses_lock);
161 racct_destroy(&new_lc->lc_racct);
162 free(new_lc, M_LOGINCLASS);
163 }
164
165 return (lc);
166 }
167
168 /*
169 * Get login class name.
170 */
171 #ifndef _SYS_SYSPROTO_H_
172 struct getloginclass_args {
173 char *namebuf;
174 size_t namelen;
175 };
176 #endif
177 /* ARGSUSED */
178 int
179 sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
180 {
181 struct loginclass *lc;
182 size_t lcnamelen;
183
184 lc = td->td_ucred->cr_loginclass;
185 lcnamelen = strlen(lc->lc_name) + 1;
186 if (lcnamelen > uap->namelen)
187 return (ERANGE);
188 return (copyout(lc->lc_name, uap->namebuf, lcnamelen));
189 }
190
191 /*
192 * Set login class name.
193 */
194 #ifndef _SYS_SYSPROTO_H_
195 struct setloginclass_args {
196 const char *namebuf;
197 };
198 #endif
199 /* ARGSUSED */
200 int
201 sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
202 {
203 struct proc *p = td->td_proc;
204 int error;
205 char lcname[MAXLOGNAME];
206 struct loginclass *newlc;
207 struct ucred *newcred, *oldcred;
208
209 error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
210 if (error != 0)
211 return (error);
212 error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
213 if (error != 0)
214 return (error);
215
216 newlc = loginclass_find(lcname);
217 if (newlc == NULL)
218 return (EINVAL);
219 newcred = crget();
220
221 PROC_LOCK(p);
222 oldcred = crcopysafe(p, newcred);
223 newcred->cr_loginclass = newlc;
224 proc_set_cred(p, newcred);
225 PROC_UNLOCK(p);
226 #ifdef RACCT
227 racct_proc_ucred_changed(p, oldcred, newcred);
228 #endif
229 loginclass_free(oldcred->cr_loginclass);
230 crfree(oldcred);
231
232 return (0);
233 }
234
235 void
236 loginclass_racct_foreach(void (*callback)(struct racct *racct,
237 void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
238 void *arg2, void *arg3)
239 {
240 struct loginclass *lc;
241
242 rw_rlock(&loginclasses_lock);
243 if (pre != NULL)
244 (pre)();
245 LIST_FOREACH(lc, &loginclasses, lc_next)
246 (callback)(lc->lc_racct, arg2, arg3);
247 if (post != NULL)
248 (post)();
249 rw_runlock(&loginclasses_lock);
250 }
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