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      1 /*
      2  * Check decoding of signal delivery.
      3  *
      4  * Copyright (c) 2016-2018 The strace developers.
      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  * 3. The name of the author may not be used to endorse or promote products
     16  *    derived from this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include "tests.h"
     31 #include <signal.h>
     32 #include <stdio.h>
     33 #include <unistd.h>
     34 
     35 static volatile int s_sig, s_code, s_pid, s_uid;
     36 
     37 static void
     38 handler(int sig, siginfo_t *info, void *ucontext)
     39 {
     40 	s_sig = info->si_signo;
     41 	s_code = info->si_code;
     42 	s_pid = info->si_pid;
     43 	s_uid = info->si_uid;
     44 }
     45 
     46 int
     47 main(void)
     48 {
     49 	static const char prefix[] = "KERNEL BUG";
     50 	int printed = 0;
     51 
     52 	const int pid = getpid();
     53 	const int uid = geteuid();
     54 
     55 	for (int sig = 1; sig <= 31; ++sig) {
     56 		if (sig == SIGKILL || sig == SIGSTOP)
     57 			continue;
     58 
     59 		sigset_t mask;
     60 		sigemptyset(&mask);
     61 		sigaddset(&mask, sig);
     62 		if (sigprocmask(SIG_UNBLOCK, &mask, NULL))
     63 			perror_msg_and_fail("sigprocmask");
     64 
     65 		static const struct sigaction act = {
     66 			.sa_sigaction = handler,
     67 			.sa_flags = SA_SIGINFO
     68 		};
     69 		if (sigaction(sig, &act, NULL))
     70 			perror_msg_and_fail("sigaction: %d", sig);
     71 
     72 		if (kill(pid, sig) != 0)
     73 			perror_msg_and_fail("kill: %d", sig);
     74 
     75 #ifdef MPERS_IS_m32
     76 		/*
     77 		 * The tracee has received a compat siginfo_t but
     78 		 * the tracer has received a native siginfo_t.
     79 		 */
     80 		const int e_sig = sig;
     81 		const int e_pid = pid;
     82 		const int e_uid = uid;
     83 #else
     84 		/*
     85 		 * If the tracee is a native process,
     86 		 * then the tracer is also native.
     87 		 * If the tracee is a compat process,
     88 		 * then the tracer is also compat.
     89 		 * Anyway, both the tracee and the tracer
     90 		 * have received the same siginfo_t.
     91 		 */
     92 		const int e_sig = s_sig;
     93 		const int e_pid = s_pid;
     94 		const int e_uid = s_uid;
     95 #endif
     96 		printf("kill(%d, %s) = 0\n", pid, signal2name(sig));
     97 		printf("--- %s {si_signo=%s, si_code=SI_USER, si_pid=%d"
     98 		       ", si_uid=%d} ---\n",
     99 		       signal2name(sig), signal2name(e_sig), e_pid, e_uid);
    100 
    101 		if (s_code || sig != s_sig || pid != s_pid || uid != s_uid) {
    102 			/*
    103 			 * The kernel has failed to initialize siginfo_t
    104 			 * properly.  There is nothing that could be done
    105 			 * on the strace side to workaround the kernel bug,
    106 			 * so just print some useful diagnostics.
    107 			 */
    108 			if (!printed) {
    109 				printed = 1;
    110 				fprintf(stderr, "%s: siginfo_t\n", prefix);
    111 			}
    112 			fprintf(stderr,
    113 				"%s: expected: si_signo=%d, si_code=%d"
    114 				", si_pid=%d, si_uid=%d\n"
    115 				"%s: received: si_signo=%d, si_code=%d"
    116 				", si_pid=%d, si_uid=%d\n",
    117 				prefix, sig, SI_USER, pid, uid,
    118 				prefix, sig, s_code, s_pid, s_uid);
    119 		}
    120 	}
    121 
    122 	if (printed) {
    123 		fprintf(stderr, "%s: end of diagnostics\n"
    124 			"*** PLEASE FIX THE KERNEL ***\n", prefix);
    125 	}
    126 
    127 	puts("+++ exited with 0 +++");
    128 	return 0;
    129 }
    130