1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2020 Google LLC.
*/
#include "vmlinux.h"
#include <errno.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
char _license[] SEC("license") = "GPL";
#define DUMMY_STORAGE_VALUE 0xdeadbeef
int monitored_pid = 0;
int inode_storage_result = -1;
int sk_storage_result = -1;
struct local_storage {
struct inode *exec_inode;
__u32 value;
struct bpf_spin_lock lock;
};
struct {
__uint(type, BPF_MAP_TYPE_INODE_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, struct local_storage);
} inode_storage_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_SK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
__type(key, int);
__type(value, struct local_storage);
} sk_storage_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, struct local_storage);
} task_storage_map SEC(".maps");
SEC("lsm/inode_unlink")
int BPF_PROG(unlink_hook, struct inode *dir, struct dentry *victim)
{
__u32 pid = bpf_get_current_pid_tgid() >> 32;
struct local_storage *storage;
bool is_self_unlink;
int err;
if (pid != monitored_pid)
return 0;
storage = bpf_task_storage_get(&task_storage_map,
bpf_get_current_task_btf(), 0, 0);
if (storage) {
/* Don't let an executable delete itself */
bpf_spin_lock(&storage->lock);
is_self_unlink = storage->exec_inode == victim->d_inode;
bpf_spin_unlock(&storage->lock);
if (is_self_unlink)
return -EPERM;
}
storage = bpf_inode_storage_get(&inode_storage_map, victim->d_inode, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!storage)
return 0;
bpf_spin_lock(&storage->lock);
if (storage->value != DUMMY_STORAGE_VALUE)
inode_storage_result = -1;
bpf_spin_unlock(&storage->lock);
err = bpf_inode_storage_delete(&inode_storage_map, victim->d_inode);
if (!err)
inode_storage_result = err;
return 0;
}
SEC("lsm/socket_bind")
int BPF_PROG(socket_bind, struct socket *sock, struct sockaddr *address,
int addrlen)
{
__u32 pid = bpf_get_current_pid_tgid() >> 32;
struct local_storage *storage;
int err;
if (pid != monitored_pid)
return 0;
storage = bpf_sk_storage_get(&sk_storage_map, sock->sk, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!storage)
return 0;
bpf_spin_lock(&storage->lock);
if (storage->value != DUMMY_STORAGE_VALUE)
sk_storage_result = -1;
bpf_spin_unlock(&storage->lock);
err = bpf_sk_storage_delete(&sk_storage_map, sock->sk);
if (!err)
sk_storage_result = err;
return 0;
}
SEC("lsm/socket_post_create")
int BPF_PROG(socket_post_create, struct socket *sock, int family, int type,
int protocol, int kern)
{
__u32 pid = bpf_get_current_pid_tgid() >> 32;
struct local_storage *storage;
if (pid != monitored_pid)
return 0;
storage = bpf_sk_storage_get(&sk_storage_map, sock->sk, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!storage)
return 0;
bpf_spin_lock(&storage->lock);
storage->value = DUMMY_STORAGE_VALUE;
bpf_spin_unlock(&storage->lock);
return 0;
}
SEC("lsm/file_open")
int BPF_PROG(file_open, struct file *file)
{
__u32 pid = bpf_get_current_pid_tgid() >> 32;
struct local_storage *storage;
if (pid != monitored_pid)
return 0;
if (!file->f_inode)
return 0;
storage = bpf_inode_storage_get(&inode_storage_map, file->f_inode, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!storage)
return 0;
bpf_spin_lock(&storage->lock);
storage->value = DUMMY_STORAGE_VALUE;
bpf_spin_unlock(&storage->lock);
return 0;
}
/* This uses the local storage to remember the inode of the binary that a
* process was originally executing.
*/
SEC("lsm/bprm_committed_creds")
void BPF_PROG(exec, struct linux_binprm *bprm)
{
struct local_storage *storage;
storage = bpf_task_storage_get(&task_storage_map,
bpf_get_current_task_btf(), 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (storage) {
bpf_spin_lock(&storage->lock);
storage->exec_inode = bprm->file->f_inode;
bpf_spin_unlock(&storage->lock);
}
}
|
