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1 /*
2  * Check decoding of kcmp syscall.
3  *
4  * Copyright (c) 2016-2017 Eugene Syromyatnikov <evgsyr@gmail.com>
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 
32 #include <asm/unistd.h>
33 #include "scno.h"
34 
35 #ifdef __NR_kcmp
36 
37 # include <fcntl.h>
38 # include <stdarg.h>
39 # include <stdint.h>
40 # include <stdio.h>
41 # include <string.h>
42 # include <unistd.h>
43 
44 # ifndef VERBOSE_FD
45 #  define VERBOSE_FD 0
46 # endif
47 
48 /*
49  * We prefer to use system headers in order to catch some possible deviations in
50  * system's headers from our perception of reality, but happy to include our own
51  * definitions as well.
52  */
53 # ifdef HAVE_LINUX_KCMP_H
54 #  include <linux/kcmp.h>
55 # else
56 #  define KCMP_FILE	0
57 #  define KCMP_VM	1
58 #  define KCMP_FILES	2
59 #  define KCMP_FS	3
60 #  define KCMP_SIGHAND	4
61 #  define KCMP_IO	5
62 #  define KCMP_SYSVSEM	6
63 # endif
64 
65 /* All other kcmp types have been added atomically */
66 # define KCMP_EPOLL_TFD	7
67 
68 # ifndef HAVE_STRUCT_KCMP_EPOLL_SLOT
69 struct kcmp_epoll_slot {
70 	uint32_t efd;
71 	uint32_t tfd;
72 	uint32_t toff;
73 };
74 # endif
75 
76 static const kernel_ulong_t kcmp_max_type = KCMP_EPOLL_TFD;
77 
78 static const char null_path[] = "/dev/null";
79 static const char zero_path[] = "/dev/zero";
80 
81 # define NULL_FD 23
82 # define ZERO_FD 42
83 
84 static void
printpidfd(const char * prefix,pid_t pid,unsigned fd)85 printpidfd(const char *prefix, pid_t pid, unsigned fd)
86 {
87 	printf("%s%d", prefix, fd);
88 }
89 
90 /*
91  * Last argument is optional and is used as follows:
92  *  * When type is KCMP_EPOLL_TFD, it signalises whether idx2 is a valid
93  *    pointer.
94  */
95 static void
do_kcmp(kernel_ulong_t pid1,kernel_ulong_t pid2,kernel_ulong_t type,const char * type_str,kernel_ulong_t idx1,kernel_ulong_t idx2,...)96 do_kcmp(kernel_ulong_t pid1, kernel_ulong_t pid2, kernel_ulong_t type,
97 	const char *type_str, kernel_ulong_t idx1, kernel_ulong_t idx2, ...)
98 {
99 	long rc;
100 	const char *errstr;
101 
102 	rc = syscall(__NR_kcmp, pid1, pid2, type, idx1, idx2);
103 	errstr = sprintrc(rc);
104 
105 	printf("kcmp(%d, %d, ", (int) pid1, (int) pid2);
106 
107 	if (type_str)
108 		printf("%s", type_str);
109 	else
110 		printf("%#x /* KCMP_??? */", (int) type);
111 
112 	if (type == KCMP_FILE) {
113 		printpidfd(", ", pid1, idx1);
114 		printpidfd(", ", pid2, idx2);
115 	} else if (type == KCMP_EPOLL_TFD) {
116 		va_list ap;
117 		int valid_ptr;
118 
119 		va_start(ap, idx2);
120 		valid_ptr = va_arg(ap, int);
121 		va_end(ap);
122 
123 		printpidfd(", ", pid1, idx1);
124 		printf(", ");
125 
126 		if (valid_ptr) {
127 			struct kcmp_epoll_slot *slot =
128 				(struct kcmp_epoll_slot *) (uintptr_t) idx2;
129 
130 			printpidfd("{efd=", pid2, slot->efd);
131 			printpidfd(", tfd=", pid2, slot->tfd);
132 			printf(", toff=%llu}", (unsigned long long) slot->toff);
133 		} else {
134 			if (idx2)
135 				printf("%#llx", (unsigned long long) idx2);
136 			else
137 				printf("NULL");
138 		}
139 	} else if (type > kcmp_max_type) {
140 		printf(", %#llx, %#llx",
141 		       (unsigned long long) idx1, (unsigned long long) idx2);
142 	}
143 
144 	printf(") = %s\n", errstr);
145 }
146 
147 int
main(void)148 main(void)
149 {
150 	static const kernel_ulong_t bogus_pid1 =
151 		(kernel_ulong_t) 0xdeadca75face1057ULL;
152 	static const kernel_ulong_t bogus_pid2 =
153 		(kernel_ulong_t) 0xdefaced1defaced2ULL;
154 	static const kernel_ulong_t bogus_type =
155 		(kernel_ulong_t) 0xbadc0dedda7adeadULL;
156 	static const kernel_ulong_t bogus_idx1 =
157 		(kernel_ulong_t) 0xdec0ded3dec0ded4ULL;
158 	static const kernel_ulong_t bogus_idx2 =
159 		(kernel_ulong_t) 0xba5e1e55deadc0deULL;
160 	static const struct kcmp_epoll_slot slot_data[] = {
161 		{ 0xdeadc0de, 0xfacef157, 0xbadc0ded },
162 		{ NULL_FD, ZERO_FD, 0 },
163 		{ 0, 0, 0 },
164 	};
165 	static kernel_ulong_t ptr_check =
166 		F8ILL_KULONG_SUPPORTED ? F8ILL_KULONG_MASK : 0;
167 
168 	int fd;
169 	unsigned i;
170 	struct kcmp_epoll_slot *slot = tail_alloc(sizeof(*slot));
171 
172 	/* Open some files to test printpidfd */
173 	fd = open(null_path, O_RDONLY);
174 	if (fd < 0)
175 		perror_msg_and_fail("open(\"%s\")", null_path);
176 	if (fd != NULL_FD) {
177 		if (dup2(fd, NULL_FD) < 0)
178 			perror_msg_and_fail("dup2(fd, NULL_FD)");
179 		close(fd);
180 	}
181 
182 	fd = open(zero_path, O_RDONLY);
183 	if (fd < 0)
184 		perror_msg_and_fail("open(\"%s\")", zero_path);
185 	if (fd != ZERO_FD) {
186 		if (dup2(fd, ZERO_FD) < 0)
187 			perror_msg_and_fail("dup2(fd, ZERO_FD)");
188 		close(fd);
189 	}
190 
191 	close(0);
192 
193 	/* Invalid values */
194 	do_kcmp(bogus_pid1, bogus_pid2, bogus_type, NULL, bogus_idx1,
195 		bogus_idx2);
196 	do_kcmp(F8ILL_KULONG_MASK, F8ILL_KULONG_MASK, kcmp_max_type + 1, NULL,
197 		0, 0);
198 
199 	/* KCMP_FILE is the only type which has additional args */
200 	do_kcmp(3141592653U, 2718281828U, ARG_STR(KCMP_FILE), bogus_idx1,
201 		bogus_idx2);
202 	do_kcmp(-1, -1, ARG_STR(KCMP_FILE), NULL_FD, ZERO_FD);
203 
204 	/* Types without additional args */
205 	do_kcmp(-1, -1, ARG_STR(KCMP_VM), bogus_idx1, bogus_idx2);
206 	do_kcmp(-1, -1, ARG_STR(KCMP_FILES), bogus_idx1, bogus_idx2);
207 	do_kcmp(-1, -1, ARG_STR(KCMP_FS), bogus_idx1, bogus_idx2);
208 	do_kcmp(-1, -1, ARG_STR(KCMP_SIGHAND), bogus_idx1, bogus_idx2);
209 	do_kcmp(-1, -1, ARG_STR(KCMP_IO), bogus_idx1, bogus_idx2);
210 	do_kcmp(-1, -1, ARG_STR(KCMP_SYSVSEM), bogus_idx1, bogus_idx2);
211 
212 	/* KCMP_EPOLL_TFD checks */
213 	do_kcmp(-1, -1, ARG_STR(KCMP_EPOLL_TFD),
214 		F8ILL_KULONG_MASK | 2718281828U, ptr_check, 0);
215 	do_kcmp(-1, -1, ARG_STR(KCMP_EPOLL_TFD),
216 		3141592653U, (uintptr_t) slot + 1, 0);
217 
218 	for (i = 0; i < ARRAY_SIZE(slot_data); i++) {
219 		memcpy(slot, slot_data + i, sizeof(*slot));
220 
221 		do_kcmp(getpid(), getppid(), ARG_STR(KCMP_EPOLL_TFD), NULL_FD,
222 			(uintptr_t) slot, 1);
223 	}
224 
225 	puts("+++ exited with 0 +++");
226 
227 	return 0;
228 }
229 
230 #else
231 
232 SKIP_MAIN_UNDEFINED("__NR_kcmp");
233 
234 #endif
235