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 static unsigned int duration;
17
18 #define TEST_STORAGE_VALUE 0xbeefdead
19
20 struct storage {
21 void *inode;
22 unsigned int value;
23 };
24
25 /* Fork and exec the provided rm binary and return the exit code of the
26 * forked process and its pid.
27 */
run_self_unlink(int * monitored_pid,const char * rm_path)28 static int run_self_unlink(int *monitored_pid, const char *rm_path)
29 {
30 int child_pid, child_status, ret;
31 int null_fd;
32
33 child_pid = fork();
34 if (child_pid == 0) {
35 null_fd = open("/dev/null", O_WRONLY);
36 dup2(null_fd, STDOUT_FILENO);
37 dup2(null_fd, STDERR_FILENO);
38 close(null_fd);
39
40 *monitored_pid = getpid();
41 /* Use the copied /usr/bin/rm to delete itself
42 * /tmp/copy_of_rm /tmp/copy_of_rm.
43 */
44 ret = execlp(rm_path, rm_path, rm_path, NULL);
45 if (ret)
46 exit(errno);
47 } else if (child_pid > 0) {
48 waitpid(child_pid, &child_status, 0);
49 return WEXITSTATUS(child_status);
50 }
51
52 return -EINVAL;
53 }
54
check_syscall_operations(int map_fd,int obj_fd)55 static bool check_syscall_operations(int map_fd, int obj_fd)
56 {
57 struct storage val = { .value = TEST_STORAGE_VALUE },
58 lookup_val = { .value = 0 };
59 int err;
60
61 /* Looking up an existing element should fail initially */
62 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
63 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem",
64 "err:%d errno:%d\n", err, errno))
65 return false;
66
67 /* Create a new element */
68 err = bpf_map_update_elem(map_fd, &obj_fd, &val, BPF_NOEXIST);
69 if (CHECK(err < 0, "bpf_map_update_elem", "err:%d errno:%d\n", err,
70 errno))
71 return false;
72
73 /* Lookup the newly created element */
74 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
75 if (CHECK(err < 0, "bpf_map_lookup_elem", "err:%d errno:%d", err,
76 errno))
77 return false;
78
79 /* Check the value of the newly created element */
80 if (CHECK(lookup_val.value != val.value, "bpf_map_lookup_elem",
81 "value got = %x errno:%d", lookup_val.value, val.value))
82 return false;
83
84 err = bpf_map_delete_elem(map_fd, &obj_fd);
85 if (CHECK(err, "bpf_map_delete_elem()", "err:%d errno:%d\n", err,
86 errno))
87 return false;
88
89 /* The lookup should fail, now that the element has been deleted */
90 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val, 0);
91 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem",
92 "err:%d errno:%d\n", err, errno))
93 return false;
94
95 return true;
96 }
97
test_test_local_storage(void)98 void test_test_local_storage(void)
99 {
100 char tmp_dir_path[] = "/tmp/local_storageXXXXXX";
101 int err, serv_sk = -1, task_fd = -1, rm_fd = -1;
102 struct local_storage *skel = NULL;
103 char tmp_exec_path[64];
104 char cmd[256];
105
106 skel = local_storage__open_and_load();
107 if (CHECK(!skel, "skel_load", "lsm skeleton failed\n"))
108 goto close_prog;
109
110 err = local_storage__attach(skel);
111 if (CHECK(err, "attach", "lsm attach failed: %d\n", err))
112 goto close_prog;
113
114 task_fd = sys_pidfd_open(getpid(), 0);
115 if (CHECK(task_fd < 0, "pidfd_open",
116 "failed to get pidfd err:%d, errno:%d", task_fd, errno))
117 goto close_prog;
118
119 if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map),
120 task_fd))
121 goto close_prog;
122
123 if (CHECK(!mkdtemp(tmp_dir_path), "mkdtemp",
124 "unable to create tmpdir: %d\n", errno))
125 goto close_prog;
126
127 snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
128 tmp_dir_path);
129 snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path);
130 if (CHECK_FAIL(system(cmd)))
131 goto close_prog_rmdir;
132
133 rm_fd = open(tmp_exec_path, O_RDONLY);
134 if (CHECK(rm_fd < 0, "open", "failed to open %s err:%d, errno:%d",
135 tmp_exec_path, rm_fd, errno))
136 goto close_prog_rmdir;
137
138 if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map),
139 rm_fd))
140 goto close_prog_rmdir;
141
142 /* Sets skel->bss->monitored_pid to the pid of the forked child
143 * forks a child process that executes tmp_exec_path and tries to
144 * unlink its executable. This operation should be denied by the loaded
145 * LSM program.
146 */
147 err = run_self_unlink(&skel->bss->monitored_pid, tmp_exec_path);
148 if (CHECK(err != EPERM, "run_self_unlink", "err %d want EPERM\n", err))
149 goto close_prog_rmdir;
150
151 /* Set the process being monitored to be the current process */
152 skel->bss->monitored_pid = getpid();
153
154 /* Move copy_of_rm to a new location so that it triggers the
155 * inode_rename LSM hook with a new_dentry that has a NULL inode ptr.
156 */
157 snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr",
158 tmp_dir_path, tmp_dir_path);
159 if (CHECK_FAIL(system(cmd)))
160 goto close_prog_rmdir;
161
162 CHECK(skel->data->inode_storage_result != 0, "inode_storage_result",
163 "inode_local_storage not set\n");
164
165 serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
166 if (CHECK(serv_sk < 0, "start_server", "failed to start server\n"))
167 goto close_prog_rmdir;
168
169 CHECK(skel->data->sk_storage_result != 0, "sk_storage_result",
170 "sk_local_storage not set\n");
171
172 if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map),
173 serv_sk))
174 goto close_prog_rmdir;
175
176 close_prog_rmdir:
177 snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path);
178 system(cmd);
179 close_prog:
180 close(serv_sk);
181 close(rm_fd);
182 close(task_fd);
183 local_storage__destroy(skel);
184 }
185