1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 * $FreeBSD$
31 */
32
33 /*
34 * Processes may set login class name using setloginclass(2). This
35 * is usually done through call to setusercontext(3), by programs
36 * such as login(1), based on information from master.passwd(5). Kernel
37 * uses this information to enforce per-class resource limits. Current
38 * login class can be determined using id(1). Login class is inherited
39 * from the parent process during fork(2). If not set, it defaults
40 * to "default".
41 *
42 * Code in this file implements setloginclass(2) and getloginclass(2)
43 * system calls, and maintains class name storage and retrieval.
44 */
45
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
48
49 #include <sys/param.h>
50 #include <sys/eventhandler.h>
51 #include <sys/kernel.h>
52 #include <sys/lock.h>
53 #include <sys/loginclass.h>
54 #include <sys/malloc.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/rctl.h>
61 #include <sys/refcount.h>
62 #include <sys/rwlock.h>
63 #include <sys/sysproto.h>
64 #include <sys/systm.h>
65
66 static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
67
68 LIST_HEAD(, loginclass) loginclasses;
69
70 /*
71 * Lock protecting loginclasses list.
72 */
73 static struct rwlock loginclasses_lock;
74 RW_SYSINIT(loginclasses_init, &loginclasses_lock, "loginclasses lock");
75
76 void
77 loginclass_hold(struct loginclass *lc)
78 {
79
80 refcount_acquire(&lc->lc_refcount);
81 }
82
83 void
84 loginclass_free(struct loginclass *lc)
85 {
86
87 if (refcount_release_if_not_last(&lc->lc_refcount))
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 lc = curthread->td_ucred->cr_loginclass;
139 if (strcmp(name, lc->lc_name) == 0) {
140 loginclass_hold(lc);
141 return (lc);
142 }
143
144 rw_rlock(&loginclasses_lock);
145 lc = loginclass_lookup(name);
146 rw_runlock(&loginclasses_lock);
147 if (lc != NULL)
148 return (lc);
149
150 new_lc = malloc(sizeof(*new_lc), M_LOGINCLASS, M_ZERO | M_WAITOK);
151 racct_create(&new_lc->lc_racct);
152 refcount_init(&new_lc->lc_refcount, 1);
153 strcpy(new_lc->lc_name, name);
154
155 rw_wlock(&loginclasses_lock);
156 /*
157 * There's a chance someone created our loginclass while we
158 * were in malloc and not holding the lock, so we have to
159 * make sure we don't insert a duplicate loginclass.
160 */
161 if ((lc = loginclass_lookup(name)) == NULL) {
162 LIST_INSERT_HEAD(&loginclasses, new_lc, lc_next);
163 rw_wunlock(&loginclasses_lock);
164 lc = new_lc;
165 } else {
166 rw_wunlock(&loginclasses_lock);
167 racct_destroy(&new_lc->lc_racct);
168 free(new_lc, M_LOGINCLASS);
169 }
170
171 return (lc);
172 }
173
174 /*
175 * Get login class name.
176 */
177 #ifndef _SYS_SYSPROTO_H_
178 struct getloginclass_args {
179 char *namebuf;
180 size_t namelen;
181 };
182 #endif
183 /* ARGSUSED */
184 int
185 sys_getloginclass(struct thread *td, struct getloginclass_args *uap)
186 {
187 struct loginclass *lc;
188 size_t lcnamelen;
189
190 lc = td->td_ucred->cr_loginclass;
191 lcnamelen = strlen(lc->lc_name) + 1;
192 if (lcnamelen > uap->namelen)
193 return (ERANGE);
194 return (copyout(lc->lc_name, uap->namebuf, lcnamelen));
195 }
196
197 /*
198 * Set login class name.
199 */
200 #ifndef _SYS_SYSPROTO_H_
201 struct setloginclass_args {
202 const char *namebuf;
203 };
204 #endif
205 /* ARGSUSED */
206 int
207 sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
208 {
209 struct proc *p = td->td_proc;
210 int error;
211 char lcname[MAXLOGNAME];
212 struct loginclass *newlc;
213 struct ucred *newcred, *oldcred;
214
215 error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
216 if (error != 0)
217 return (error);
218 error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
219 if (error != 0)
220 return (error);
221
222 newlc = loginclass_find(lcname);
223 if (newlc == NULL)
224 return (EINVAL);
225 newcred = crget();
226
227 PROC_LOCK(p);
228 oldcred = crcopysafe(p, newcred);
229 newcred->cr_loginclass = newlc;
230 proc_set_cred(p, newcred);
231 #ifdef RACCT
232 racct_proc_ucred_changed(p, oldcred, newcred);
233 crhold(newcred);
234 #endif
235 PROC_UNLOCK(p);
236 #ifdef RCTL
237 rctl_proc_ucred_changed(p, newcred);
238 crfree(newcred);
239 #endif
240 loginclass_free(oldcred->cr_loginclass);
241 crfree(oldcred);
242
243 return (0);
244 }
245
246 void
247 loginclass_racct_foreach(void (*callback)(struct racct *racct,
248 void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
249 void *arg2, void *arg3)
250 {
251 struct loginclass *lc;
252
253 rw_rlock(&loginclasses_lock);
254 if (pre != NULL)
255 (pre)();
256 LIST_FOREACH(lc, &loginclasses, lc_next)
257 (callback)(lc->lc_racct, arg2, arg3);
258 if (post != NULL)
259 (post)();
260 rw_runlock(&loginclasses_lock);
261 }
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