1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * Copyright 2020 Google LLC. 5 */ 6 7 #include "vmlinux.h" 8 #include <errno.h> 9 #include <bpf/bpf_helpers.h> 10 #include <bpf/bpf_tracing.h> 11 12 char _license[] SEC("license") = "GPL"; 13 14 #define DUMMY_STORAGE_VALUE 0xdeadbeef 15 16 int monitored_pid = 0; 17 int inode_storage_result = -1; 18 int sk_storage_result = -1; 19 20 struct local_storage { 21 struct inode *exec_inode; 22 __u32 value; 23 struct bpf_spin_lock lock; 24 }; 25 26 struct { 27 __uint(type, BPF_MAP_TYPE_INODE_STORAGE); 28 __uint(map_flags, BPF_F_NO_PREALLOC); 29 __type(key, int); 30 __type(value, struct local_storage); 31 } inode_storage_map SEC(".maps"); 32 33 struct { 34 __uint(type, BPF_MAP_TYPE_SK_STORAGE); 35 __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE); 36 __type(key, int); 37 __type(value, struct local_storage); 38 } sk_storage_map SEC(".maps"); 39 40 struct { 41 __uint(type, BPF_MAP_TYPE_TASK_STORAGE); 42 __uint(map_flags, BPF_F_NO_PREALLOC); 43 __type(key, int); 44 __type(value, struct local_storage); 45 } task_storage_map SEC(".maps"); 46 47 SEC("lsm/inode_unlink") 48 int BPF_PROG(unlink_hook, struct inode *dir, struct dentry *victim) 49 { 50 __u32 pid = bpf_get_current_pid_tgid() >> 32; 51 struct local_storage *storage; 52 bool is_self_unlink; 53 int err; 54 55 if (pid != monitored_pid) 56 return 0; 57 58 storage = bpf_task_storage_get(&task_storage_map, 59 bpf_get_current_task_btf(), 0, 0); 60 if (storage) { 61 /* Don't let an executable delete itself */ 62 bpf_spin_lock(&storage->lock); 63 is_self_unlink = storage->exec_inode == victim->d_inode; 64 bpf_spin_unlock(&storage->lock); 65 if (is_self_unlink) 66 return -EPERM; 67 } 68 69 storage = bpf_inode_storage_get(&inode_storage_map, victim->d_inode, 0, 70 BPF_LOCAL_STORAGE_GET_F_CREATE); 71 if (!storage) 72 return 0; 73 74 bpf_spin_lock(&storage->lock); 75 if (storage->value != DUMMY_STORAGE_VALUE) 76 inode_storage_result = -1; 77 bpf_spin_unlock(&storage->lock); 78 79 err = bpf_inode_storage_delete(&inode_storage_map, victim->d_inode); 80 if (!err) 81 inode_storage_result = err; 82 83 return 0; 84 } 85 86 SEC("lsm/socket_bind") 87 int BPF_PROG(socket_bind, struct socket *sock, struct sockaddr *address, 88 int addrlen) 89 { 90 __u32 pid = bpf_get_current_pid_tgid() >> 32; 91 struct local_storage *storage; 92 int err; 93 94 if (pid != monitored_pid) 95 return 0; 96 97 storage = bpf_sk_storage_get(&sk_storage_map, sock->sk, 0, 98 BPF_LOCAL_STORAGE_GET_F_CREATE); 99 if (!storage) 100 return 0; 101 102 bpf_spin_lock(&storage->lock); 103 if (storage->value != DUMMY_STORAGE_VALUE) 104 sk_storage_result = -1; 105 bpf_spin_unlock(&storage->lock); 106 107 err = bpf_sk_storage_delete(&sk_storage_map, sock->sk); 108 if (!err) 109 sk_storage_result = err; 110 111 return 0; 112 } 113 114 SEC("lsm/socket_post_create") 115 int BPF_PROG(socket_post_create, struct socket *sock, int family, int type, 116 int protocol, int kern) 117 { 118 __u32 pid = bpf_get_current_pid_tgid() >> 32; 119 struct local_storage *storage; 120 121 if (pid != monitored_pid) 122 return 0; 123 124 storage = bpf_sk_storage_get(&sk_storage_map, sock->sk, 0, 125 BPF_LOCAL_STORAGE_GET_F_CREATE); 126 if (!storage) 127 return 0; 128 129 bpf_spin_lock(&storage->lock); 130 storage->value = DUMMY_STORAGE_VALUE; 131 bpf_spin_unlock(&storage->lock); 132 133 return 0; 134 } 135 136 SEC("lsm/file_open") 137 int BPF_PROG(file_open, struct file *file) 138 { 139 __u32 pid = bpf_get_current_pid_tgid() >> 32; 140 struct local_storage *storage; 141 142 if (pid != monitored_pid) 143 return 0; 144 145 if (!file->f_inode) 146 return 0; 147 148 storage = bpf_inode_storage_get(&inode_storage_map, file->f_inode, 0, 149 BPF_LOCAL_STORAGE_GET_F_CREATE); 150 if (!storage) 151 return 0; 152 153 bpf_spin_lock(&storage->lock); 154 storage->value = DUMMY_STORAGE_VALUE; 155 bpf_spin_unlock(&storage->lock); 156 return 0; 157 } 158 159 /* This uses the local storage to remember the inode of the binary that a 160 * process was originally executing. 161 */ 162 SEC("lsm/bprm_committed_creds") 163 void BPF_PROG(exec, struct linux_binprm *bprm) 164 { 165 struct local_storage *storage; 166 167 storage = bpf_task_storage_get(&task_storage_map, 168 bpf_get_current_task_btf(), 0, 169 BPF_LOCAL_STORAGE_GET_F_CREATE); 170 if (storage) { 171 bpf_spin_lock(&storage->lock); 172 storage->exec_inode = bprm->file->f_inode; 173 bpf_spin_unlock(&storage->lock); 174 } 175 } 176