1/*-
2 * Copyright (c) 2023 The FreeBSD Foundation
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 *
6 * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
7 * under sponsorship from the FreeBSD Foundation.
8 */
9
10#include <sys/param.h>
11#include <sys/syscall.h>
12#include <sys/sysctl.h>
13
14#include <atf-c.h>
15#include <errno.h>
16#include <signal.h>
17#include <stdatomic.h>
18#include <stdbool.h>
19#include <stdio.h>
20
21static sig_atomic_t sigsys_cnt;
22
23#define	SAVEDVALUE	"savedsignosys"
24
25static void
26sigsys_handler(int signo, siginfo_t *si, void *ucp)
27{
28	sigsys_cnt++;
29}
30
31static void
32sigsys_test(int knob)
33{
34	struct sigaction sa;
35
36	memset(&sa, 0, sizeof(sa));
37	sa.sa_sigaction = sigsys_handler;
38	sa.sa_flags = SA_SIGINFO;
39	ATF_REQUIRE(sigaction(SIGSYS, &sa, NULL) == 0);
40
41	ATF_REQUIRE(syscall(273) == -1);	/* reserved */
42	ATF_CHECK_ERRNO(ENOSYS, true);
43	atomic_signal_fence(memory_order_seq_cst);
44	ATF_CHECK_EQ(1 * knob, sigsys_cnt);
45
46	ATF_REQUIRE(syscall(440) == -1);	/* SYS_kse_switchin */
47	ATF_CHECK_ERRNO(ENOSYS, true);
48	atomic_signal_fence(memory_order_seq_cst);
49	ATF_CHECK_EQ(2 * knob, sigsys_cnt);
50
51	/* Hope this is enough for say next two months */
52	ATF_REQUIRE(syscall(3000000) == -1);
53	ATF_CHECK_ERRNO(ENOSYS, true);
54	atomic_signal_fence(memory_order_seq_cst);
55	ATF_CHECK_EQ(3 * knob, sigsys_cnt);
56
57	ATF_REQUIRE(syscall(SYS_afs3_syscall) == -1);
58	ATF_CHECK_ERRNO(ENOSYS, true);
59	atomic_signal_fence(memory_order_seq_cst);
60	ATF_CHECK_EQ(4 * knob, sigsys_cnt);
61}
62
63static void
64sysctlset(const char *name, int val)
65{
66	size_t oldlen = sizeof(int);
67	int oldval;
68	char buf[80];
69
70	ATF_REQUIRE(sysctlbyname(name, &oldval, &oldlen, NULL, 0) == 0);
71
72	/* Store old %name in a symlink for cleanup */
73	snprintf(buf, sizeof(buf), "%d", oldval);
74	ATF_REQUIRE(symlink(buf, SAVEDVALUE) == 0);
75
76	ATF_REQUIRE(sysctlbyname(name, NULL, NULL, &val, sizeof(val)) == 0);
77}
78
79static void
80sysctlcleanup(const char *name)
81{
82	size_t oldlen;
83	int n, oldval;
84	char buf[80];
85
86	if ((n = readlink(SAVEDVALUE, buf, sizeof(buf))) > 0) {
87		buf[MIN((size_t)n, sizeof(buf) - 1)] = '\0';
88		if (sscanf(buf, "%d", &oldval) == 1) {
89			oldlen = sizeof(oldval);
90			(void)sysctlbyname(name, NULL, 0,
91			    &oldval, oldlen);
92		}
93	}
94	(void)unlink(SAVEDVALUE);
95}
96
97ATF_TC_WITH_CLEANUP(sigsys_test_on);
98ATF_TC_HEAD(sigsys_test_on, tc)
99{
100	atf_tc_set_md_var(tc, "require.user", "root");
101	atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
102	atf_tc_set_md_var(tc, "descr",
103	    "Testing delivery of SIGSYS on invalid syscalls");
104}
105
106ATF_TC_BODY(sigsys_test_on, tc)
107{
108	sysctlset("kern.signosys", 1);
109	sigsys_test(1);
110}
111
112ATF_TC_CLEANUP(sigsys_test_on, tc)
113{
114	sysctlcleanup("kern.signosys");
115}
116
117ATF_TC_WITH_CLEANUP(sigsys_test_off);
118ATF_TC_HEAD(sigsys_test_off, tc)
119{
120	atf_tc_set_md_var(tc, "require.user", "root");
121	atf_tc_set_md_var(tc, "require.config", "allow_sysctl_side_effects");
122	atf_tc_set_md_var(tc, "descr",
123	    "Testing SIGSYS silence on invalid syscalls");
124}
125
126ATF_TC_BODY(sigsys_test_off, tc)
127{
128	sysctlset("kern.signosys", 0);
129	sigsys_test(0);
130}
131
132ATF_TC_CLEANUP(sigsys_test_off, tc)
133{
134	sysctlcleanup("kern.signosys");
135}
136
137ATF_TP_ADD_TCS(tp)
138{
139	ATF_TP_ADD_TC(tp, sigsys_test_on);
140	ATF_TP_ADD_TC(tp, sigsys_test_off);
141	return (atf_no_error());
142}
143