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
15 #ifndef __NR_pidfd_open
16 #define __NR_pidfd_open 434
17 #endif
18
sys_pidfd_open(pid_t pid,unsigned int flags)19 static inline int sys_pidfd_open(pid_t pid, unsigned int flags)
20 {
21 return syscall(__NR_pidfd_open, pid, flags);
22 }
23
24 static unsigned int duration;
25
26 #define TEST_STORAGE_VALUE 0xbeefdead
27
28 struct storage {
29 void *inode;
30 unsigned int value;
31 /* Lock ensures that spin locked versions of local stoage operations
32 * also work, most operations in this tests are still single threaded
33 */
34 struct bpf_spin_lock lock;
35 };
36
37 /* Fork and exec the provided rm binary and return the exit code of the
38 * forked process and its pid.
39 */
run_self_unlink(int * monitored_pid,const char * rm_path)40 static int run_self_unlink(int *monitored_pid, const char *rm_path)
41 {
42 int child_pid, child_status, ret;
43 int null_fd;
44
45 child_pid = fork();
46 if (child_pid == 0) {
47 null_fd = open("/dev/null", O_WRONLY);
48 dup2(null_fd, STDOUT_FILENO);
49 dup2(null_fd, STDERR_FILENO);
50 close(null_fd);
51
52 *monitored_pid = getpid();
53 /* Use the copied /usr/bin/rm to delete itself
54 * /tmp/copy_of_rm /tmp/copy_of_rm.
55 */
56 ret = execlp(rm_path, rm_path, rm_path, NULL);
57 if (ret)
58 exit(errno);
59 } else if (child_pid > 0) {
60 waitpid(child_pid, &child_status, 0);
61 return WEXITSTATUS(child_status);
62 }
63
64 return -EINVAL;
65 }
66
check_syscall_operations(int map_fd,int obj_fd)67 static bool check_syscall_operations(int map_fd, int obj_fd)
68 {
69 struct storage val = { .value = TEST_STORAGE_VALUE, .lock = { 0 } },
70 lookup_val = { .value = 0, .lock = { 0 } };
71 int err;
72
73 /* Looking up an existing element should fail initially */
74 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val,
75 BPF_F_LOCK);
76 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem",
77 "err:%d errno:%d\n", err, errno))
78 return false;
79
80 /* Create a new element */
81 err = bpf_map_update_elem(map_fd, &obj_fd, &val,
82 BPF_NOEXIST | BPF_F_LOCK);
83 if (CHECK(err < 0, "bpf_map_update_elem", "err:%d errno:%d\n", err,
84 errno))
85 return false;
86
87 /* Lookup the newly created element */
88 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val,
89 BPF_F_LOCK);
90 if (CHECK(err < 0, "bpf_map_lookup_elem", "err:%d errno:%d", err,
91 errno))
92 return false;
93
94 /* Check the value of the newly created element */
95 if (CHECK(lookup_val.value != val.value, "bpf_map_lookup_elem",
96 "value got = %x errno:%d", lookup_val.value, val.value))
97 return false;
98
99 err = bpf_map_delete_elem(map_fd, &obj_fd);
100 if (CHECK(err, "bpf_map_delete_elem()", "err:%d errno:%d\n", err,
101 errno))
102 return false;
103
104 /* The lookup should fail, now that the element has been deleted */
105 err = bpf_map_lookup_elem_flags(map_fd, &obj_fd, &lookup_val,
106 BPF_F_LOCK);
107 if (CHECK(!err || errno != ENOENT, "bpf_map_lookup_elem",
108 "err:%d errno:%d\n", err, errno))
109 return false;
110
111 return true;
112 }
113
test_test_local_storage(void)114 void test_test_local_storage(void)
115 {
116 char tmp_dir_path[] = "/tmp/local_storageXXXXXX";
117 int err, serv_sk = -1, task_fd = -1, rm_fd = -1;
118 struct local_storage *skel = NULL;
119 char tmp_exec_path[64];
120 char cmd[256];
121
122 skel = local_storage__open_and_load();
123 if (CHECK(!skel, "skel_load", "lsm skeleton failed\n"))
124 goto close_prog;
125
126 err = local_storage__attach(skel);
127 if (CHECK(err, "attach", "lsm attach failed: %d\n", err))
128 goto close_prog;
129
130 task_fd = sys_pidfd_open(getpid(), 0);
131 if (CHECK(task_fd < 0, "pidfd_open",
132 "failed to get pidfd err:%d, errno:%d", task_fd, errno))
133 goto close_prog;
134
135 if (!check_syscall_operations(bpf_map__fd(skel->maps.task_storage_map),
136 task_fd))
137 goto close_prog;
138
139 if (CHECK(!mkdtemp(tmp_dir_path), "mkdtemp",
140 "unable to create tmpdir: %d\n", errno))
141 goto close_prog;
142
143 snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
144 tmp_dir_path);
145 snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path);
146 if (CHECK_FAIL(system(cmd)))
147 goto close_prog_rmdir;
148
149 rm_fd = open(tmp_exec_path, O_RDONLY);
150 if (CHECK(rm_fd < 0, "open", "failed to open %s err:%d, errno:%d",
151 tmp_exec_path, rm_fd, errno))
152 goto close_prog_rmdir;
153
154 if (!check_syscall_operations(bpf_map__fd(skel->maps.inode_storage_map),
155 rm_fd))
156 goto close_prog_rmdir;
157
158 /* Sets skel->bss->monitored_pid to the pid of the forked child
159 * forks a child process that executes tmp_exec_path and tries to
160 * unlink its executable. This operation should be denied by the loaded
161 * LSM program.
162 */
163 err = run_self_unlink(&skel->bss->monitored_pid, tmp_exec_path);
164 if (CHECK(err != EPERM, "run_self_unlink", "err %d want EPERM\n", err))
165 goto close_prog_rmdir;
166
167 /* Set the process being monitored to be the current process */
168 skel->bss->monitored_pid = getpid();
169
170 /* Move copy_of_rm to a new location so that it triggers the
171 * inode_rename LSM hook with a new_dentry that has a NULL inode ptr.
172 */
173 snprintf(cmd, sizeof(cmd), "mv %s/copy_of_rm %s/check_null_ptr",
174 tmp_dir_path, tmp_dir_path);
175 if (CHECK_FAIL(system(cmd)))
176 goto close_prog_rmdir;
177
178 CHECK(skel->data->inode_storage_result != 0, "inode_storage_result",
179 "inode_local_storage not set\n");
180
181 serv_sk = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
182 if (CHECK(serv_sk < 0, "start_server", "failed to start server\n"))
183 goto close_prog_rmdir;
184
185 CHECK(skel->data->sk_storage_result != 0, "sk_storage_result",
186 "sk_local_storage not set\n");
187
188 if (!check_syscall_operations(bpf_map__fd(skel->maps.sk_storage_map),
189 serv_sk))
190 goto close_prog_rmdir;
191
192 close_prog_rmdir:
193 snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir_path);
194 system(cmd);
195 close_prog:
196 close(serv_sk);
197 close(rm_fd);
198 close(task_fd);
199 local_storage__destroy(skel);
200 }
201