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 int task_storage_result = -1; 20 21 struct local_storage { 22 struct inode *exec_inode; 23 __u32 value; 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_SK_STORAGE); 42 __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE); 43 __type(key, int); 44 __type(value, struct local_storage); 45 } sk_storage_map2 SEC(".maps"); 46 47 struct { 48 __uint(type, BPF_MAP_TYPE_TASK_STORAGE); 49 __uint(map_flags, BPF_F_NO_PREALLOC); 50 __type(key, int); 51 __type(value, struct local_storage); 52 } task_storage_map SEC(".maps"); 53 54 struct { 55 __uint(type, BPF_MAP_TYPE_TASK_STORAGE); 56 __uint(map_flags, BPF_F_NO_PREALLOC); 57 __type(key, int); 58 __type(value, struct local_storage); 59 } task_storage_map2 SEC(".maps"); 60 61 SEC("lsm/inode_unlink") 62 int BPF_PROG(unlink_hook, struct inode *dir, struct dentry *victim) 63 { 64 __u32 pid = bpf_get_current_pid_tgid() >> 32; 65 struct bpf_local_storage *local_storage; 66 struct local_storage *storage; 67 struct task_struct *task; 68 bool is_self_unlink; 69 70 if (pid != monitored_pid) 71 return 0; 72 73 task = bpf_get_current_task_btf(); 74 if (!task) 75 return 0; 76 77 task_storage_result = -1; 78 79 storage = bpf_task_storage_get(&task_storage_map, task, 0, 0); 80 if (!storage) 81 return 0; 82 83 /* Don't let an executable delete itself */ 84 is_self_unlink = storage->exec_inode == victim->d_inode; 85 86 storage = bpf_task_storage_get(&task_storage_map2, task, 0, 87 BPF_LOCAL_STORAGE_GET_F_CREATE); 88 if (!storage || storage->value) 89 return 0; 90 91 if (bpf_task_storage_delete(&task_storage_map, task)) 92 return 0; 93 94 /* Ensure that the task_storage_map is disconnected from the storage. 95 * The storage memory should not be freed back to the 96 * bpf_mem_alloc. 97 */ 98 local_storage = task->bpf_storage; 99 if (!local_storage || local_storage->smap) 100 return 0; 101 102 task_storage_result = 0; 103 104 return is_self_unlink ? -EPERM : 0; 105 } 106 107 SEC("lsm.s/inode_rename") 108 int BPF_PROG(inode_rename, struct inode *old_dir, struct dentry *old_dentry, 109 struct inode *new_dir, struct dentry *new_dentry, 110 unsigned int flags) 111 { 112 struct local_storage *storage; 113 int err; 114 115 /* new_dentry->d_inode can be NULL when the inode is renamed to a file 116 * that did not exist before. The helper should be able to handle this 117 * NULL pointer. 118 */ 119 bpf_inode_storage_get(&inode_storage_map, new_dentry->d_inode, 0, 120 BPF_LOCAL_STORAGE_GET_F_CREATE); 121 122 storage = bpf_inode_storage_get(&inode_storage_map, old_dentry->d_inode, 123 0, 0); 124 if (!storage) 125 return 0; 126 127 if (storage->value != DUMMY_STORAGE_VALUE) 128 inode_storage_result = -1; 129 130 err = bpf_inode_storage_delete(&inode_storage_map, old_dentry->d_inode); 131 if (!err) 132 inode_storage_result = err; 133 134 return 0; 135 } 136 137 SEC("lsm.s/socket_bind") 138 int BPF_PROG(socket_bind, struct socket *sock, struct sockaddr *address, 139 int addrlen) 140 { 141 __u32 pid = bpf_get_current_pid_tgid() >> 32; 142 struct local_storage *storage; 143 struct sock *sk = sock->sk; 144 145 if (pid != monitored_pid || !sk) 146 return 0; 147 148 storage = bpf_sk_storage_get(&sk_storage_map, sk, 0, 0); 149 if (!storage) 150 return 0; 151 152 sk_storage_result = -1; 153 if (storage->value != DUMMY_STORAGE_VALUE) 154 return 0; 155 156 /* This tests that we can associate multiple elements 157 * with the local storage. 158 */ 159 storage = bpf_sk_storage_get(&sk_storage_map2, sk, 0, 160 BPF_LOCAL_STORAGE_GET_F_CREATE); 161 if (!storage) 162 return 0; 163 164 if (bpf_sk_storage_delete(&sk_storage_map2, sk)) 165 return 0; 166 167 storage = bpf_sk_storage_get(&sk_storage_map2, sk, 0, 168 BPF_LOCAL_STORAGE_GET_F_CREATE); 169 if (!storage) 170 return 0; 171 172 if (bpf_sk_storage_delete(&sk_storage_map, sk)) 173 return 0; 174 175 /* Ensure that the sk_storage_map is disconnected from the storage. */ 176 if (!sk->sk_bpf_storage || sk->sk_bpf_storage->smap) 177 return 0; 178 179 sk_storage_result = 0; 180 return 0; 181 } 182 183 SEC("lsm.s/socket_post_create") 184 int BPF_PROG(socket_post_create, struct socket *sock, int family, int type, 185 int protocol, int kern) 186 { 187 __u32 pid = bpf_get_current_pid_tgid() >> 32; 188 struct local_storage *storage; 189 struct sock *sk = sock->sk; 190 191 if (pid != monitored_pid || !sk) 192 return 0; 193 194 storage = bpf_sk_storage_get(&sk_storage_map, sk, 0, 195 BPF_LOCAL_STORAGE_GET_F_CREATE); 196 if (!storage) 197 return 0; 198 199 storage->value = DUMMY_STORAGE_VALUE; 200 201 return 0; 202 } 203 204 /* This uses the local storage to remember the inode of the binary that a 205 * process was originally executing. 206 */ 207 SEC("lsm.s/bprm_committed_creds") 208 void BPF_PROG(exec, struct linux_binprm *bprm) 209 { 210 __u32 pid = bpf_get_current_pid_tgid() >> 32; 211 struct local_storage *storage; 212 213 if (pid != monitored_pid) 214 return; 215 216 storage = bpf_task_storage_get(&task_storage_map, 217 bpf_get_current_task_btf(), 0, 218 BPF_LOCAL_STORAGE_GET_F_CREATE); 219 if (storage) 220 storage->exec_inode = bprm->file->f_inode; 221 222 storage = bpf_inode_storage_get(&inode_storage_map, bprm->file->f_inode, 223 0, BPF_LOCAL_STORAGE_GET_F_CREATE); 224 if (!storage) 225 return; 226 227 storage->value = DUMMY_STORAGE_VALUE; 228 } 229