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printsiginfo.c: add a comment about personality detection for SIGSYS
[strace] / printsiginfo.c
1 /*
2  * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
3  * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
4  * Copyright (c) 1993-1996 Rick Sladkey <jrs@world.std.com>
5  * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
6  * Copyright (c) 2001 John Hughes <john@Calva.COM>
7  * Copyright (c) 2013 Denys Vlasenko <vda.linux@googlemail.com>
8  * Copyright (c) 2011-2015 Dmitry V. Levin <ldv@altlinux.org>
9  * Copyright (c) 2015 Elvira Khabirova <lineprinter0@gmail.com>
10  * Copyright (c) 2015-2017 The strace developers.
11  * All rights reserved.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. The name of the author may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35
36 #include "defs.h"
37
38 #include DEF_MPERS_TYPE(siginfo_t)
39
40 #include <signal.h>
41 #include <linux/audit.h>
42
43 #include MPERS_DEFS
44
45 #ifndef IN_MPERS
46 #include "printsiginfo.h"
47 #endif
48
49 #include "xlat/audit_arch.h"
50 #include "xlat/sigbus_codes.h"
51 #include "xlat/sigchld_codes.h"
52 #include "xlat/sigfpe_codes.h"
53 #include "xlat/sigill_codes.h"
54 #include "xlat/siginfo_codes.h"
55 #include "xlat/sigpoll_codes.h"
56 #include "xlat/sigprof_codes.h"
57 #include "xlat/sigsegv_codes.h"
58 #include "xlat/sigsys_codes.h"
59 #include "xlat/sigtrap_codes.h"
60
61 #ifdef SIGEMT
62 # include "xlat/sigemt_codes.h"
63 #endif
64
65 #ifndef SI_FROMUSER
66 # define SI_FROMUSER(sip)       ((sip)->si_code <= 0)
67 #endif
68
69 static void
70 printsigsource(const siginfo_t *sip)
71 {
72         tprintf(", si_pid=%u, si_uid=%u",
73                 (unsigned int) sip->si_pid,
74                 (unsigned int) sip->si_uid);
75 }
76
77 static void
78 printsigval(const siginfo_t *sip)
79 {
80         tprintf(", si_value={int=%d, ptr=", sip->si_int);
81         printaddr(ptr_to_kulong(sip->si_ptr));
82         tprints("}");
83 }
84
85 static void
86 print_si_code(int si_signo, unsigned int si_code)
87 {
88         const char *code = xlookup(siginfo_codes, si_code);
89
90         if (!code) {
91                 switch (si_signo) {
92                 case SIGTRAP:
93                         code = xlookup(sigtrap_codes, si_code);
94                         break;
95                 case SIGCHLD:
96                         code = xlookup(sigchld_codes, si_code);
97                         break;
98                 case SIGPOLL:
99                         code = xlookup(sigpoll_codes, si_code);
100                         break;
101                 case SIGPROF:
102                         code = xlookup(sigprof_codes, si_code);
103                         break;
104                 case SIGILL:
105                         code = xlookup(sigill_codes, si_code);
106                         break;
107 #ifdef SIGEMT
108                 case SIGEMT:
109                         code = xlookup(sigemt_codes, si_code);
110                         break;
111 #endif
112                 case SIGFPE:
113                         code = xlookup(sigfpe_codes, si_code);
114                         break;
115                 case SIGSEGV:
116                         code = xlookup(sigsegv_codes, si_code);
117                         break;
118                 case SIGBUS:
119                         code = xlookup(sigbus_codes, si_code);
120                         break;
121                 case SIGSYS:
122                         code = xlookup(sigsys_codes, si_code);
123                         break;
124                 }
125         }
126
127         if (code)
128                 tprints(code);
129         else
130                 tprintf("%#x", si_code);
131 }
132
133 static void
134 print_si_info(const siginfo_t *sip)
135 {
136         if (sip->si_errno) {
137                 tprints(", si_errno=");
138                 if ((unsigned) sip->si_errno < nerrnos
139                     && errnoent[sip->si_errno])
140                         tprints(errnoent[sip->si_errno]);
141                 else
142                         tprintf("%d", sip->si_errno);
143         }
144
145         if (SI_FROMUSER(sip)) {
146                 switch (sip->si_code) {
147                 case SI_USER:
148                         printsigsource(sip);
149                         break;
150                 case SI_TKILL:
151                         printsigsource(sip);
152                         break;
153 #if defined HAVE_SIGINFO_T_SI_TIMERID && defined HAVE_SIGINFO_T_SI_OVERRUN
154                 case SI_TIMER:
155                         tprintf(", si_timerid=%#x, si_overrun=%d",
156                                 sip->si_timerid, sip->si_overrun);
157                         printsigval(sip);
158                         break;
159 #endif
160                 default:
161                         printsigsource(sip);
162                         if (sip->si_ptr)
163                                 printsigval(sip);
164                         break;
165                 }
166         } else {
167                 switch (sip->si_signo) {
168                 case SIGCHLD:
169                         printsigsource(sip);
170                         tprints(", si_status=");
171                         if (sip->si_code == CLD_EXITED)
172                                 tprintf("%d", sip->si_status);
173                         else
174                                 printsignal(sip->si_status);
175                         tprintf(", si_utime=%llu, si_stime=%llu",
176                                 zero_extend_signed_to_ull(sip->si_utime),
177                                 zero_extend_signed_to_ull(sip->si_stime));
178                         break;
179                 case SIGILL: case SIGFPE:
180                 case SIGSEGV: case SIGBUS:
181                         tprints(", si_addr=");
182                         printaddr(ptr_to_kulong(sip->si_addr));
183                         break;
184                 case SIGPOLL:
185                         switch (sip->si_code) {
186                         case POLL_IN: case POLL_OUT: case POLL_MSG:
187                                 tprintf(", si_band=%ld",
188                                         (long) sip->si_band);
189                                 break;
190                         }
191                         break;
192 #ifdef HAVE_SIGINFO_T_SI_SYSCALL
193                 case SIGSYS: {
194                         /*
195                          * Note that we can safely use the personlity set in
196                          * current_personality  here (and don't have to guess it
197                          * based on X32_SYSCALL_BIT and si_arch, for example):
198                          *  - The signal is delivered as a result of seccomp
199                          *    filtering to the process executing forbidden
200                          *    syscall.
201                          *  - We have set the personality for the tracee during
202                          *    the syscall entering.
203                          *  - The current_personality is reliably switched in
204                          *    the next_event routine, it is set to the
205                          *    personality of the last call made (the one that
206                          *    triggered the signal delivery).
207                          *  - Looks like there are no other cases where SIGSYS
208                          *    is delivered from the kernel so far.
209                          */
210                         const char *scname =
211                                 syscall_name((unsigned) sip->si_syscall);
212
213                         tprints(", si_call_addr=");
214                         printaddr(ptr_to_kulong(sip->si_call_addr));
215                         tprints(", si_syscall=");
216                         if (scname)
217                                 tprintf("__NR_%s", scname);
218                         else
219                                 tprintf("%u", (unsigned) sip->si_syscall);
220                         tprints(", si_arch=");
221                         printxval(audit_arch, sip->si_arch, "AUDIT_ARCH_???");
222                         break;
223                 }
224 #endif
225                 default:
226                         if (sip->si_pid || sip->si_uid)
227                                 printsigsource(sip);
228                         if (sip->si_ptr)
229                                 printsigval(sip);
230                 }
231         }
232 }
233
234 #ifdef IN_MPERS
235 static
236 #endif
237 void
238 printsiginfo(const siginfo_t *sip)
239 {
240         if (sip->si_signo == 0) {
241                 tprints("{}");
242                 return;
243         }
244         tprints("{si_signo=");
245         printsignal(sip->si_signo);
246
247         tprints(", si_code=");
248         print_si_code(sip->si_signo, sip->si_code);
249
250 #ifdef SI_NOINFO
251         if (sip->si_code != SI_NOINFO)
252 #endif
253                 print_si_info(sip);
254
255         tprints("}");
256 }
257
258 MPERS_PRINTER_DECL(void, printsiginfo_at,
259                    struct tcb *const tcp, const kernel_ulong_t addr)
260 {
261         siginfo_t si;
262
263         if (!umove_or_printaddr(tcp, addr, &si))
264                 printsiginfo(&si);
265 }
266
267 static bool
268 print_siginfo_t(struct tcb *tcp, void *elem_buf, size_t elem_size, void *data)
269 {
270         printsiginfo((const siginfo_t *) elem_buf);
271         return true;
272 }
273
274 MPERS_PRINTER_DECL(void, print_siginfo_array, struct tcb *const tcp,
275                    const kernel_ulong_t addr, const kernel_ulong_t len)
276 {
277         siginfo_t si;
278
279         print_array(tcp, addr, len, &si, sizeof(si),
280                     umoven_or_printaddr, print_siginfo_t, 0);
281 }