xref: /titanic_44/usr/src/uts/common/syscall/sigqueue.c (revision 55434c770c89aa1b84474f2559a106803511aba0)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
28 
29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
30 
31 #include <sys/param.h>
32 #include <sys/types.h>
33 #include <sys/sysmacros.h>
34 #include <sys/systm.h>
35 #include <sys/errno.h>
36 #include <sys/proc.h>
37 #include <sys/procset.h>
38 #include <sys/fault.h>
39 #include <sys/signal.h>
40 #include <sys/siginfo.h>
41 #include <sys/debug.h>
42 
43 static int
44 sigqkill(pid_t pid, sigsend_t *sigsend)
45 {
46 	proc_t *p;
47 	int error;
48 
49 	if ((uint_t)sigsend->sig >= NSIG)
50 		return (EINVAL);
51 
52 	if (pid == -1) {
53 		procset_t set;
54 
55 		setprocset(&set, POP_AND, P_ALL, P_MYID, P_ALL, P_MYID);
56 		error = sigsendset(&set, sigsend);
57 	} else if (pid > 0) {
58 		mutex_enter(&pidlock);
59 		if ((p = prfind(pid)) == NULL || p->p_stat == SIDL)
60 			error = ESRCH;
61 		else {
62 			error = sigsendproc(p, sigsend);
63 			if (error == 0 && sigsend->perm == 0)
64 				error = EPERM;
65 		}
66 		mutex_exit(&pidlock);
67 	} else {
68 		int nfound = 0;
69 		pid_t pgid;
70 
71 		if (pid == 0)
72 			pgid = ttoproc(curthread)->p_pgrp;
73 		else
74 			pgid = -pid;
75 
76 		error = 0;
77 		mutex_enter(&pidlock);
78 		for (p = pgfind(pgid); p && !error; p = p->p_pglink) {
79 			if (p->p_stat != SIDL) {
80 				nfound++;
81 				error = sigsendproc(p, sigsend);
82 			}
83 		}
84 		mutex_exit(&pidlock);
85 		if (nfound == 0)
86 			error = ESRCH;
87 		else if (error == 0 && sigsend->perm == 0)
88 			error = EPERM;
89 	}
90 
91 	return (error);
92 }
93 
94 
95 /*
96  * for implementations that don't require binary compatibility,
97  * the kill system call may be made into a library call to the
98  * sigsend system call
99  */
100 int
101 kill(pid_t pid, int sig)
102 {
103 	int error;
104 	sigsend_t v;
105 
106 	bzero(&v, sizeof (v));
107 	v.sig = sig;
108 	v.checkperm = 1;
109 	v.sicode = SI_USER;
110 	if ((error = sigqkill(pid, &v)) != 0)
111 		return (set_errno(error));
112 	return (0);
113 }
114 
115 /*
116  * The handling of small unions, like the sigval argument to sigqueue,
117  * is architecture dependent.  We have adopted the convention that the
118  * value itself is passed in the storage which crosses the kernel
119  * protection boundary.  This procedure will accept a scalar argument,
120  * and store it in the appropriate value member of the sigsend_t structure.
121  */
122 int
123 sigqueue(pid_t pid, int sig, /* union sigval */ void *value,
124 	int si_code, int block)
125 {
126 	int error;
127 	sigsend_t v;
128 	sigqhdr_t *sqh;
129 	proc_t *p = curproc;
130 
131 	/* The si_code value must indicate the signal will be queued */
132 	if (pid <= 0 || !sigwillqueue(sig, si_code))
133 		return (set_errno(EINVAL));
134 
135 	if ((sqh = p->p_sigqhdr) == NULL) {
136 		/* Allocate sigqueue pool first time */
137 		sqh = sigqhdralloc(sizeof (sigqueue_t), _SIGQUEUE_MAX);
138 		mutex_enter(&p->p_lock);
139 		if (p->p_sigqhdr == NULL) {
140 			/* hang the pool head on proc */
141 			p->p_sigqhdr = sqh;
142 		} else {
143 			/* another lwp allocated the pool, free ours */
144 			sigqhdrfree(sqh);
145 			sqh = p->p_sigqhdr;
146 		}
147 		mutex_exit(&p->p_lock);
148 	}
149 
150 	do {
151 		bzero(&v, sizeof (v));
152 		v.sig = sig;
153 		v.checkperm = 1;
154 		v.sicode = si_code;
155 		v.value.sival_ptr = value;
156 		if ((error = sigqkill(pid, &v)) != EAGAIN || !block)
157 			break;
158 		/* block waiting for another chance to allocate a sigqueue_t */
159 		mutex_enter(&sqh->sqb_lock);
160 		while (sqh->sqb_count == 0) {
161 			if (!cv_wait_sig(&sqh->sqb_cv, &sqh->sqb_lock)) {
162 				error = EINTR;
163 				break;
164 			}
165 		}
166 		mutex_exit(&sqh->sqb_lock);
167 	} while (error == EAGAIN);
168 
169 	if (error)
170 		return (set_errno(error));
171 	return (0);
172 }
173 
174 #ifdef _SYSCALL32_IMPL
175 /*
176  * sigqueue32 - System call entry point for 32-bit callers on LP64 kernel,
177  * needed to handle the 32-bit sigvals as correctly as we can.  We always
178  * assume that a 32-bit caller is passing an int. A 64-bit recipient
179  * that expects an int will therefore get it correctly.  A 32-bit
180  * recipient will also get it correctly since siginfo_kto32() uses
181  * sival_int in the conversion.  Since a 32-bit pointer has the same
182  * size and address in the sigval, it also converts correctly so that
183  * two 32-bit apps can exchange a pointer value.  However, this means
184  * that a pointer sent by a 32-bit caller will be seen in the upper half
185  * by a 64-bit recipient, and only the upper half of a 64-bit pointer will
186  * be seen by a 32-bit recipient.  This is the best solution that does
187  * not require severe hacking of the sigval union.  Anyways, what it
188  * means to be sending pointers between processes with dissimilar
189  * models is unclear.
190  */
191 int
192 sigqueue32(pid_t pid, int sig, /* union sigval32 */ caddr32_t value,
193 	int si_code, int block)
194 {
195 	union sigval sv;
196 
197 	bzero(&sv, sizeof (sv));
198 	sv.sival_int = (int)value;
199 	return (sigqueue(pid, sig, sv.sival_ptr, si_code, block));
200 }
201 #endif
202