1/* $NetBSD$ */
2
3/*-
4 * Copyright (c) 2012 Jared D. McNeill <jmcneill@invisible.ca>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD$");
31
32#include <sys/param.h>
33#include <sys/proc.h>
34#include <sys/systm.h>
35#include <sys/module.h>
36#include <sys/atomic.h>
37#include <sys/syscallvar.h>
38
39#include "syscallemu.h"
40
41#if !defined(__HAVE_SYSCALL_INTERN)
42#error syscallemu requires __HAVE_SYSCALL_INTERN
43#endif
44
45static specificdata_key_t syscallemu_data_key;
46static unsigned int syscallemu_refcnt;
47
48static const struct syscall_package syscallemu_syscalls[] = {
49	{ SYS_syscallemu,	0, (sy_call_t *)sys_syscallemu	},
50	{ 0, 0, NULL },
51};
52
53struct syscallemu_data *
54syscallemu_getsce(struct proc *p)
55{
56	return proc_getspecific(p, syscallemu_data_key);
57}
58
59void
60syscallemu_setsce(struct proc *p, struct syscallemu_data *sce)
61{
62	proc_setspecific(p, syscallemu_data_key, sce);
63}
64
65/*
66 * specificdata destructor
67 */
68static void
69syscallemu_dtor(void *priv)
70{
71	struct syscallemu_data *sce = priv;
72
73	kmem_free(sce, sizeof(*sce));
74	atomic_dec_uint(&syscallemu_refcnt);
75}
76
77/*
78 * Allocate private storage for the syscallemu parameters and stash it
79 * in process specificdata. This can only be called once per process.
80 *
81 * Returns EINVAL if the specified start address falls after the end.
82 * Returns EACCESS if syscallemu has already been configured for this process.
83 */
84int
85sys_syscallemu(lwp_t *l, const struct sys_syscallemu_args *uap,
86    register_t *retval)
87{
88	/* {
89		syscallarg(uintptr_t) user_start;
90		syscallarg(uintptr_t) user_end;
91	} */
92	vaddr_t user_start = (vaddr_t)SCARG(uap, user_start);
93	vaddr_t user_end = (vaddr_t)SCARG(uap, user_end);
94	struct syscallemu_data *sce;
95	struct proc *p = l->l_proc;
96
97	if (syscallemu_getsce(p) != NULL)
98		return EACCES;
99	if (user_start >= user_end)
100		return EINVAL;
101
102	sce = kmem_alloc(sizeof(*sce), KM_SLEEP);
103	sce->sce_user_start = user_start;
104	sce->sce_user_end = user_end;
105	sce->sce_md_syscall = md_syscallemu(p);
106	KASSERT(sce->sce_md_syscall != NULL);
107
108	atomic_inc_uint(&syscallemu_refcnt);
109	syscallemu_setsce(p, sce);
110
111#ifdef DEBUG
112	printf("syscallemu: enabled for pid %d\n", p->p_pid);
113#endif
114
115	return 0;
116}
117
118/*
119 * Initialize the syscallemu module
120 */
121static int
122syscallemu_init(void)
123{
124	int error;
125
126	syscallemu_refcnt = 0;
127
128	/* XXX workaround for kern/45781 */
129	if (emul_netbsd.e_sysent[SYS_syscallemu].sy_call == sys_nosys) {
130		printf("syscallemu: applying workaround for kern/45781\n");
131		emul_netbsd.e_sysent[SYS_syscallemu].sy_call = sys_nomodule;
132	}
133	emul_netbsd.e_sysent[SYS_syscallemu].sy_narg =
134	    sizeof(struct sys_syscallemu_args) / sizeof(register_t);
135	emul_netbsd.e_sysent[SYS_syscallemu].sy_argsize =
136	    sizeof(struct sys_syscallemu_args);
137
138	error = proc_specific_key_create(&syscallemu_data_key, syscallemu_dtor);
139	if (error) {
140		printf("syscallemu: couldn't create proc specific key (%d)\n",
141		    error);
142		return error;
143	}
144
145	error = syscall_establish(NULL, syscallemu_syscalls);
146	if (error) {
147		printf("syscallemu: couldn't establish syscalls\n");
148		proc_specific_key_delete(syscallemu_data_key);
149		return ENXIO;
150	}
151
152	return 0;
153}
154
155/*
156 * Finalize the syscallemu module
157 */
158static int
159syscallemu_fini(void)
160{
161	if (syscallemu_refcnt > 0)
162		return EBUSY;
163
164	syscall_disestablish(NULL, syscallemu_syscalls);
165	proc_specific_key_delete(syscallemu_data_key);
166	return 0;
167}
168
169/*
170 * Module glue
171 */
172MODULE(MODULE_CLASS_MISC, syscallemu, NULL);
173
174static int
175syscallemu_modcmd(modcmd_t cmd, void *arg)
176{
177	switch (cmd) {
178	case MODULE_CMD_INIT:
179		return syscallemu_init();
180	case MODULE_CMD_FINI:
181		return syscallemu_fini();
182	case MODULE_CMD_AUTOUNLOAD:
183		return EBUSY;
184	default:
185		return ENOTTY;
186	}
187}
188