1 // SPDX-License-Identifier: GPL-2.0
2 
3 /*
4  * Copyright (C) 2020 Google LLC.
5  */
6 
7 #include <test_progs.h>
8 #include <sys/mman.h>
9 #include <sys/wait.h>
10 #include <unistd.h>
11 #include <malloc.h>
12 #include <stdlib.h>
13 
14 #include "lsm.skel.h"
15 
16 char *CMD_ARGS[] = {"true", NULL};
17 
18 #define GET_PAGE_ADDR(ADDR, PAGE_SIZE)					\
19 	(char *)(((unsigned long) (ADDR + PAGE_SIZE)) & ~(PAGE_SIZE-1))
20 
stack_mprotect(void)21 int stack_mprotect(void)
22 {
23 	void *buf;
24 	long sz;
25 	int ret;
26 
27 	sz = sysconf(_SC_PAGESIZE);
28 	if (sz < 0)
29 		return sz;
30 
31 	buf = alloca(sz * 3);
32 	ret = mprotect(GET_PAGE_ADDR(buf, sz), sz,
33 		       PROT_READ | PROT_WRITE | PROT_EXEC);
34 	return ret;
35 }
36 
exec_cmd(int * monitored_pid)37 int exec_cmd(int *monitored_pid)
38 {
39 	int child_pid, child_status;
40 
41 	child_pid = fork();
42 	if (child_pid == 0) {
43 		*monitored_pid = getpid();
44 		execvp(CMD_ARGS[0], CMD_ARGS);
45 		return -EINVAL;
46 	} else if (child_pid > 0) {
47 		waitpid(child_pid, &child_status, 0);
48 		return child_status;
49 	}
50 
51 	return -EINVAL;
52 }
53 
test_lsm(struct lsm * skel)54 static int test_lsm(struct lsm *skel)
55 {
56 	struct bpf_link *link;
57 	int buf = 1234;
58 	int err;
59 
60 	err = lsm__attach(skel);
61 	if (!ASSERT_OK(err, "attach"))
62 		return err;
63 
64 	/* Check that already linked program can't be attached again. */
65 	link = bpf_program__attach(skel->progs.test_int_hook);
66 	if (!ASSERT_ERR_PTR(link, "attach_link"))
67 		return -1;
68 
69 	err = exec_cmd(&skel->bss->monitored_pid);
70 	if (!ASSERT_OK(err, "exec_cmd"))
71 		return err;
72 
73 	ASSERT_EQ(skel->bss->bprm_count, 1, "bprm_count");
74 
75 	skel->bss->monitored_pid = getpid();
76 
77 	err = stack_mprotect();
78 	if (!ASSERT_EQ(errno, EPERM, "stack_mprotect"))
79 		return err;
80 
81 	ASSERT_EQ(skel->bss->mprotect_count, 1, "mprotect_count");
82 
83 	syscall(__NR_setdomainname, &buf, -2L);
84 	syscall(__NR_setdomainname, 0, -3L);
85 	syscall(__NR_setdomainname, ~0L, -4L);
86 
87 	ASSERT_EQ(skel->bss->copy_test, 3, "copy_test");
88 
89 	lsm__detach(skel);
90 
91 	skel->bss->copy_test = 0;
92 	skel->bss->bprm_count = 0;
93 	skel->bss->mprotect_count = 0;
94 	return 0;
95 }
96 
test_test_lsm(void)97 void test_test_lsm(void)
98 {
99 	struct lsm *skel = NULL;
100 	int err;
101 
102 	skel = lsm__open_and_load();
103 	if (!ASSERT_OK_PTR(skel, "lsm_skel_load"))
104 		goto close_prog;
105 
106 	err = test_lsm(skel);
107 	if (!ASSERT_OK(err, "test_lsm_first_attach"))
108 		goto close_prog;
109 
110 	err = test_lsm(skel);
111 	ASSERT_OK(err, "test_lsm_second_attach");
112 
113 close_prog:
114 	lsm__destroy(skel);
115 }
116