xref: /linux/tools/testing/selftests/bpf/prog_tests/d_path.c (revision 981368e1440b76f68b1ac8f5fb14e739f80ecc4e)
1 // SPDX-License-Identifier: GPL-2.0
2 #define _GNU_SOURCE
3 #include <test_progs.h>
4 #include <sys/stat.h>
5 #include <linux/sched.h>
6 #include <sys/syscall.h>
7 
8 #define MAX_PATH_LEN		128
9 #define MAX_FILES		7
10 
11 #include "test_d_path.skel.h"
12 #include "test_d_path_check_rdonly_mem.skel.h"
13 #include "test_d_path_check_types.skel.h"
14 
15 /* sys_close_range is not around for long time, so let's
16  * make sure we can call it on systems with older glibc
17  */
18 #ifndef __NR_close_range
19 #ifdef __alpha__
20 #define __NR_close_range 546
21 #else
22 #define __NR_close_range 436
23 #endif
24 #endif
25 
26 static int duration;
27 
28 static struct {
29 	__u32 cnt;
30 	char paths[MAX_FILES][MAX_PATH_LEN];
31 } src;
32 
33 static int set_pathname(int fd, pid_t pid)
34 {
35 	char buf[MAX_PATH_LEN];
36 
37 	snprintf(buf, MAX_PATH_LEN, "/proc/%d/fd/%d", pid, fd);
38 	return readlink(buf, src.paths[src.cnt++], MAX_PATH_LEN);
39 }
40 
41 static int trigger_fstat_events(pid_t pid)
42 {
43 	int sockfd = -1, procfd = -1, devfd = -1;
44 	int localfd = -1, indicatorfd = -1;
45 	int pipefd[2] = { -1, -1 };
46 	struct stat fileStat;
47 	int ret = -1;
48 
49 	/* unmountable pseudo-filesystems */
50 	if (CHECK(pipe(pipefd) < 0, "trigger", "pipe failed\n"))
51 		return ret;
52 	/* unmountable pseudo-filesystems */
53 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
54 	if (CHECK(sockfd < 0, "trigger", "socket failed\n"))
55 		goto out_close;
56 	/* mountable pseudo-filesystems */
57 	procfd = open("/proc/self/comm", O_RDONLY);
58 	if (CHECK(procfd < 0, "trigger", "open /proc/self/comm failed\n"))
59 		goto out_close;
60 	devfd = open("/dev/urandom", O_RDONLY);
61 	if (CHECK(devfd < 0, "trigger", "open /dev/urandom failed\n"))
62 		goto out_close;
63 	localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY, 0644);
64 	if (CHECK(localfd < 0, "trigger", "open /tmp/d_path_loadgen.txt failed\n"))
65 		goto out_close;
66 	/* bpf_d_path will return path with (deleted) */
67 	remove("/tmp/d_path_loadgen.txt");
68 	indicatorfd = open("/tmp/", O_PATH);
69 	if (CHECK(indicatorfd < 0, "trigger", "open /tmp/ failed\n"))
70 		goto out_close;
71 
72 	ret = set_pathname(pipefd[0], pid);
73 	if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[0]\n"))
74 		goto out_close;
75 	ret = set_pathname(pipefd[1], pid);
76 	if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[1]\n"))
77 		goto out_close;
78 	ret = set_pathname(sockfd, pid);
79 	if (CHECK(ret < 0, "trigger", "set_pathname failed for socket\n"))
80 		goto out_close;
81 	ret = set_pathname(procfd, pid);
82 	if (CHECK(ret < 0, "trigger", "set_pathname failed for proc\n"))
83 		goto out_close;
84 	ret = set_pathname(devfd, pid);
85 	if (CHECK(ret < 0, "trigger", "set_pathname failed for dev\n"))
86 		goto out_close;
87 	ret = set_pathname(localfd, pid);
88 	if (CHECK(ret < 0, "trigger", "set_pathname failed for file\n"))
89 		goto out_close;
90 	ret = set_pathname(indicatorfd, pid);
91 	if (CHECK(ret < 0, "trigger", "set_pathname failed for dir\n"))
92 		goto out_close;
93 
94 	/* triggers vfs_getattr */
95 	fstat(pipefd[0], &fileStat);
96 	fstat(pipefd[1], &fileStat);
97 	fstat(sockfd, &fileStat);
98 	fstat(procfd, &fileStat);
99 	fstat(devfd, &fileStat);
100 	fstat(localfd, &fileStat);
101 	fstat(indicatorfd, &fileStat);
102 
103 out_close:
104 	/* sys_close no longer triggers filp_close, but we can
105 	 * call sys_close_range instead which still does
106 	 */
107 #define close(fd) syscall(__NR_close_range, fd, fd, 0)
108 
109 	close(pipefd[0]);
110 	close(pipefd[1]);
111 	close(sockfd);
112 	close(procfd);
113 	close(devfd);
114 	close(localfd);
115 	close(indicatorfd);
116 
117 #undef close
118 	return ret;
119 }
120 
121 static void test_d_path_basic(void)
122 {
123 	struct test_d_path__bss *bss;
124 	struct test_d_path *skel;
125 	int err;
126 
127 	skel = test_d_path__open_and_load();
128 	if (CHECK(!skel, "setup", "d_path skeleton failed\n"))
129 		goto cleanup;
130 
131 	err = test_d_path__attach(skel);
132 	if (CHECK(err, "setup", "attach failed: %d\n", err))
133 		goto cleanup;
134 
135 	bss = skel->bss;
136 	bss->my_pid = getpid();
137 
138 	err = trigger_fstat_events(bss->my_pid);
139 	if (err < 0)
140 		goto cleanup;
141 
142 	if (CHECK(!bss->called_stat,
143 		  "stat",
144 		  "trampoline for security_inode_getattr was not called\n"))
145 		goto cleanup;
146 
147 	if (CHECK(!bss->called_close,
148 		  "close",
149 		  "trampoline for filp_close was not called\n"))
150 		goto cleanup;
151 
152 	for (int i = 0; i < MAX_FILES; i++) {
153 		CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN),
154 		      "check",
155 		      "failed to get stat path[%d]: %s vs %s\n",
156 		      i, src.paths[i], bss->paths_stat[i]);
157 		CHECK(strncmp(src.paths[i], bss->paths_close[i], MAX_PATH_LEN),
158 		      "check",
159 		      "failed to get close path[%d]: %s vs %s\n",
160 		      i, src.paths[i], bss->paths_close[i]);
161 		/* The d_path helper returns size plus NUL char, hence + 1 */
162 		CHECK(bss->rets_stat[i] != strlen(bss->paths_stat[i]) + 1,
163 		      "check",
164 		      "failed to match stat return [%d]: %d vs %zd [%s]\n",
165 		      i, bss->rets_stat[i], strlen(bss->paths_stat[i]) + 1,
166 		      bss->paths_stat[i]);
167 		CHECK(bss->rets_close[i] != strlen(bss->paths_stat[i]) + 1,
168 		      "check",
169 		      "failed to match stat return [%d]: %d vs %zd [%s]\n",
170 		      i, bss->rets_close[i], strlen(bss->paths_close[i]) + 1,
171 		      bss->paths_stat[i]);
172 	}
173 
174 cleanup:
175 	test_d_path__destroy(skel);
176 }
177 
178 static void test_d_path_check_rdonly_mem(void)
179 {
180 	struct test_d_path_check_rdonly_mem *skel;
181 
182 	skel = test_d_path_check_rdonly_mem__open_and_load();
183 	ASSERT_ERR_PTR(skel, "unexpected_load_overwriting_rdonly_mem");
184 
185 	test_d_path_check_rdonly_mem__destroy(skel);
186 }
187 
188 static void test_d_path_check_types(void)
189 {
190 	struct test_d_path_check_types *skel;
191 
192 	skel = test_d_path_check_types__open_and_load();
193 	ASSERT_ERR_PTR(skel, "unexpected_load_passing_wrong_type");
194 
195 	test_d_path_check_types__destroy(skel);
196 }
197 
198 void test_d_path(void)
199 {
200 	if (test__start_subtest("basic"))
201 		test_d_path_basic();
202 
203 	if (test__start_subtest("check_rdonly_mem"))
204 		test_d_path_check_rdonly_mem();
205 
206 	if (test__start_subtest("check_alloc_mem"))
207 		test_d_path_check_types();
208 }
209