1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * Copyright (C) 2020 Google LLC.
5 */
6
7 #include <asm-generic/errno-base.h>
8 #include <sys/stat.h>
9 #include <test_progs.h>
10 #include <linux/limits.h>
11
12 #include "local_storage.skel.h"
13 #include "network_helpers.h"
14 #include "task_local_storage_helpers.h"
15
16 #define TEST_STORAGE_VALUE 0xbeefdead
17
18 struct storage {
19 void *inode;
20 unsigned int value;
21 };
22
23 /* Fork and exec the provided rm binary and return the exit code of the
24 * forked process and its pid.
25 */
run_self_unlink(struct local_storage * skel,const char * rm_path)26 static int run_self_unlink(struct local_storage *skel, const char *rm_path)
27 {
28 int child_pid, child_status, ret;
29 int null_fd;
30
31 child_pid = fork();
32 if (child_pid == 0) {
33 null_fd = open("/dev/null", O_WRONLY);
34 dup2(null_fd, STDOUT_FILENO);
35 dup2(null_fd, STDERR_FILENO);
36 close(null_fd);
37
38 skel->bss->monitored_pid = getpid();
39 /* Use the copied /usr/bin/rm to delete itself
40 * /tmp/copy_of_rm /tmp/copy_of_rm.
41 */
42 ret = execlp(rm_path, rm_path, rm_path, NULL);
43 if (ret)
44 exit(errno);
45 } else if (child_pid > 0) {
46 waitpid(child_pid, &child_status, 0);
47 ASSERT_EQ(skel->data->task_storage_result, 0, "task_storage_result");
48 return WEXITSTATUS(child_status);
49 }
50
51 return -EINVAL;
52 }
53
check_syscall_operations(int map_fd,int obj_fd)54 static bool check_syscall_operations(int map_fd, int obj_fd)
55 {
56 struct storage val = { .value = TEST_STORAGE_VALUE },
57 lookup_val = { .value = 0 };
58 int err;
59
60 /* Looking up an existing element should fail initially */
61 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
62 if (!ASSERT_EQ(err, -ENOENT, "bpf_map_lookup_elem"))
63 return false;
64
65 /* Create a new element */
66 err = bpf_map_update_elem(map_fd, &obj_fd, &val, BPF_NOEXIST);
67 if (!ASSERT_OK(err, "bpf_map_update_elem"))
68 return false;
69
70 /* Lookup the newly created element */
71 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
72 if (!ASSERT_OK(err, "bpf_map_lookup_elem"))
73 return false;
74
75 /* Check the value of the newly created element */
76 if (!ASSERT_EQ(lookup_val.value, val.value, "bpf_map_lookup_elem"))
77 return false;
78
79 err = bpf_map_delete_elem(map_fd, &obj_fd);
80 if (!ASSERT_OK(err, "bpf_map_delete_elem()"))
81 return false;
82
83 /* The lookup should fail, now that the element has been deleted */
84 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
85 if (!ASSERT_EQ(err, -ENOENT, "bpf_map_lookup_elem"))
86 return false;
87
88 return true;
89 }
90
test_test_local_storage(void)91 void test_test_local_storage(void)
92 {
93 char tmp_dir_path[] = "/tmp/local_storageXXXXXX";
94 int err, serv_sk = -1, task_fd = -1, rm_fd = -1;
95 struct local_storage *skel = NULL;
96 char tmp_exec_path[64];
97 char cmd[256];
98
99 skel = local_storage__open_and_load();
100 if (!ASSERT_OK_PTR(skel, "skel_load"))
101 goto close_prog;
102
103 err = local_storage__attach(skel);
104 if (!ASSERT_OK(err, "attach"))
105 goto close_prog;
106
107 task_fd = sys_pidfd_open(getpid(), 0);
108 if (!ASSERT_GE(task_fd, 0, "pidfd_open"))
109 goto close_prog;
110
111 if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map),
112 task_fd))
113 goto close_prog;
114
115 if (!ASSERT_OK_PTR(mkdtemp(tmp_dir_path), "mkdtemp"))
116 goto close_prog;
117
118 snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
119 tmp_dir_path);
120 snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path);
121 if (!ASSERT_OK(system(cmd), "system(cp)"))
122 goto close_prog_rmdir;
123
124 rm_fd = open(tmp_exec_path, O_RDONLY);
125 if (!ASSERT_GE(rm_fd, 0, "open(tmp_exec_path)"))
126 goto close_prog_rmdir;
127
128 if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map),
129 rm_fd))
130 goto close_prog_rmdir;
131
132 /* Sets skel->bss->monitored_pid to the pid of the forked child
133 * forks a child process that executes tmp_exec_path and tries to
134 * unlink its executable. This operation should be denied by the loaded
135 * LSM program.
136 */
137 err = run_self_unlink(skel, tmp_exec_path);
138 if (!ASSERT_EQ(err, EPERM, "run_self_unlink"))
139 goto close_prog_rmdir;
140
141 /* Set the process being monitored to be the current process */
142 skel->bss->monitored_pid = getpid();
143
144 /* Move copy_of_rm to a new location so that it triggers the
145 * inode_rename LSM hook with a new_dentry that has a NULL inode ptr.
146 */
147 snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr",
148 tmp_dir_path, tmp_dir_path);
149 if (!ASSERT_OK(system(cmd), "system(mv)"))
150 goto close_prog_rmdir;
151
152 ASSERT_EQ(skel->data->inode_storage_result, 0, "inode_storage_result");
153
154 serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
155 if (!ASSERT_GE(serv_sk, 0, "start_server"))
156 goto close_prog_rmdir;
157
158 ASSERT_EQ(skel->data->sk_storage_result, 0, "sk_storage_result");
159
160 if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map),
161 serv_sk))
162 goto close_prog_rmdir;
163
164 close_prog_rmdir:
165 snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path);
166 system(cmd);
167 close_prog:
168 close(serv_sk);
169 close(rm_fd);
170 close(task_fd);
171 local_storage__destroy(skel);
172 }
173