1 /*
2 * Copyright (C) 2013 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <signal.h>
30 #include <string.h>
31
32 #include <platform/bionic/reserved_signals.h>
33
34 extern "C" void __restore_rt(void);
35 extern "C" void __restore(void);
36
37 #if defined(__LP64__)
38
39 extern "C" int __rt_sigaction(int, const struct __kernel_sigaction*, struct __kernel_sigaction*, size_t);
40
sigaction(int signal,const struct sigaction * bionic_new_action,struct sigaction * bionic_old_action)41 int sigaction(int signal, const struct sigaction* bionic_new_action, struct sigaction* bionic_old_action) {
42 __kernel_sigaction kernel_new_action = {};
43 if (bionic_new_action != nullptr) {
44 kernel_new_action.sa_flags = bionic_new_action->sa_flags;
45 kernel_new_action.sa_handler = bionic_new_action->sa_handler;
46 // Don't filter signals here; if the caller asked for everything to be blocked, we should obey.
47 kernel_new_action.sa_mask = bionic_new_action->sa_mask;
48 #if defined(__x86_64__)
49 // riscv64 doesn't have sa_restorer. For arm64 and 32-bit x86, unwinding
50 // works best if you just let the kernel supply the default restorer
51 // from [vdso]. gdb doesn't care, but libgcc needs the nop that the
52 // kernel includes before the actual code. (We could add that ourselves,
53 // but why bother?)
54 // TODO: why do arm32 and x86-64 need this to unwind through signal handlers?
55 kernel_new_action.sa_restorer = bionic_new_action->sa_restorer;
56 if (!(kernel_new_action.sa_flags & SA_RESTORER)) {
57 kernel_new_action.sa_flags |= SA_RESTORER;
58 kernel_new_action.sa_restorer = &__restore_rt;
59 }
60 #endif
61 }
62
63 __kernel_sigaction kernel_old_action;
64 int result = __rt_sigaction(signal,
65 (bionic_new_action != nullptr) ? &kernel_new_action : nullptr,
66 (bionic_old_action != nullptr) ? &kernel_old_action : nullptr,
67 sizeof(sigset_t));
68
69 if (bionic_old_action != nullptr) {
70 bionic_old_action->sa_flags = kernel_old_action.sa_flags;
71 bionic_old_action->sa_handler = kernel_old_action.sa_handler;
72 bionic_old_action->sa_mask = kernel_old_action.sa_mask;
73 #if defined(SA_RESTORER)
74 bionic_old_action->sa_restorer = kernel_old_action.sa_restorer;
75 #endif
76 }
77
78 return result;
79 }
80
81 __strong_alias(sigaction64, sigaction);
82
83 #else
84
85 extern "C" int __rt_sigaction(int, const struct sigaction64*, struct sigaction64*, size_t);
86
87 // sigaction and sigaction64 get interposed in ART: ensure that we don't end up calling
88 // sigchain sigaction -> bionic sigaction -> sigchain sigaction64 -> bionic sigaction64
89 // by extracting the implementation of sigaction64 to a static function.
__sigaction64(int signal,const struct sigaction64 * bionic_new,struct sigaction64 * bionic_old)90 static int __sigaction64(int signal, const struct sigaction64* bionic_new,
91 struct sigaction64* bionic_old) {
92 struct sigaction64 kernel_new = {};
93 if (bionic_new) {
94 kernel_new = *bionic_new;
95 #if defined(__arm__)
96 // (See sa_restorer comment in sigaction() above.)
97 if (!(kernel_new.sa_flags & SA_RESTORER)) {
98 kernel_new.sa_flags |= SA_RESTORER;
99 kernel_new.sa_restorer = (kernel_new.sa_flags & SA_SIGINFO) ? &__restore_rt : &__restore;
100 }
101 #endif
102 // Don't filter signals here; if the caller asked for everything to be blocked, we should obey.
103 kernel_new.sa_mask = kernel_new.sa_mask;
104 }
105
106 return __rt_sigaction(signal, bionic_new ? &kernel_new : nullptr, bionic_old,
107 sizeof(kernel_new.sa_mask));
108 }
109
sigaction(int signal,const struct sigaction * bionic_new,struct sigaction * bionic_old)110 int sigaction(int signal, const struct sigaction* bionic_new, struct sigaction* bionic_old) {
111 // The 32-bit ABI is broken. struct sigaction includes a too-small sigset_t,
112 // so we have to translate to struct sigaction64 first.
113 struct sigaction64 kernel_new = {};
114 if (bionic_new) {
115 kernel_new.sa_flags = bionic_new->sa_flags;
116 kernel_new.sa_handler = bionic_new->sa_handler;
117 #if defined(SA_RESTORER)
118 kernel_new.sa_restorer = bionic_new->sa_restorer;
119 #endif
120 // Don't filter signals here; if the caller asked for everything to be blocked, we should obey.
121 memcpy(&kernel_new.sa_mask, &bionic_new->sa_mask, sizeof(bionic_new->sa_mask));
122 }
123
124 struct sigaction64 kernel_old;
125 int result = __sigaction64(signal, bionic_new ? &kernel_new : nullptr, &kernel_old);
126 if (bionic_old) {
127 *bionic_old = {};
128 bionic_old->sa_flags = kernel_old.sa_flags;
129 bionic_old->sa_handler = kernel_old.sa_handler;
130 #if defined(SA_RESTORER)
131 bionic_old->sa_restorer = kernel_old.sa_restorer;
132 #endif
133 memcpy(&bionic_old->sa_mask, &kernel_old.sa_mask, sizeof(bionic_old->sa_mask));
134 }
135 return result;
136 }
137
sigaction64(int signal,const struct sigaction64 * bionic_new,struct sigaction64 * bionic_old)138 int sigaction64(int signal, const struct sigaction64* bionic_new, struct sigaction64* bionic_old) {
139 return __sigaction64(signal, bionic_new, bionic_old);
140 }
141
142 #endif
143