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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 | // 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; int task_storage_result = -1; struct local_storage { struct inode *exec_inode; __u32 value; }; 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_SK_STORAGE); __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE); __type(key, int); __type(value, struct local_storage); } sk_storage_map2 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"); 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_map2 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 bpf_local_storage *local_storage; struct local_storage *storage; struct task_struct *task; bool is_self_unlink; if (pid != monitored_pid) return 0; task = bpf_get_current_task_btf(); if (!task) return 0; task_storage_result = -1; storage = bpf_task_storage_get(&task_storage_map, task, 0, 0); if (!storage) return 0; /* Don't let an executable delete itself */ is_self_unlink = storage->exec_inode == victim->d_inode; storage = bpf_task_storage_get(&task_storage_map2, task, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (!storage || storage->value) return 0; if (bpf_task_storage_delete(&task_storage_map, task)) return 0; /* Ensure that the task_storage_map is disconnected from the storage. * The storage memory should not be freed back to the * bpf_mem_alloc. */ local_storage = task->bpf_storage; if (!local_storage || local_storage->smap) return 0; task_storage_result = 0; return is_self_unlink ? -EPERM : 0; } SEC("lsm.s/inode_rename") int BPF_PROG(inode_rename, struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) { struct local_storage *storage; int err; /* new_dentry->d_inode can be NULL when the inode is renamed to a file * that did not exist before. The helper should be able to handle this * NULL pointer. */ bpf_inode_storage_get(&inode_storage_map, new_dentry->d_inode, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); storage = bpf_inode_storage_get(&inode_storage_map, old_dentry->d_inode, 0, 0); if (!storage) return 0; if (storage->value != DUMMY_STORAGE_VALUE) inode_storage_result = -1; err = bpf_inode_storage_delete(&inode_storage_map, old_dentry->d_inode); if (!err) inode_storage_result = err; return 0; } SEC("lsm.s/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; if (pid != monitored_pid) return 0; storage = bpf_sk_storage_get(&sk_storage_map, sock->sk, 0, 0); if (!storage) return 0; sk_storage_result = -1; if (storage->value != DUMMY_STORAGE_VALUE) return 0; /* This tests that we can associate multiple elements * with the local storage. */ storage = bpf_sk_storage_get(&sk_storage_map2, sock->sk, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (!storage) return 0; if (bpf_sk_storage_delete(&sk_storage_map2, sock->sk)) return 0; storage = bpf_sk_storage_get(&sk_storage_map2, sock->sk, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (!storage) return 0; if (bpf_sk_storage_delete(&sk_storage_map, sock->sk)) return 0; /* Ensure that the sk_storage_map is disconnected from the storage. */ if (!sock->sk->sk_bpf_storage || sock->sk->sk_bpf_storage->smap) return 0; sk_storage_result = 0; return 0; } SEC("lsm.s/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; storage->value = DUMMY_STORAGE_VALUE; return 0; } /* This uses the local storage to remember the inode of the binary that a * process was originally executing. */ SEC("lsm.s/bprm_committed_creds") void BPF_PROG(exec, struct linux_binprm *bprm) { __u32 pid = bpf_get_current_pid_tgid() >> 32; struct local_storage *storage; if (pid != monitored_pid) return; storage = bpf_task_storage_get(&task_storage_map, bpf_get_current_task_btf(), 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (storage) storage->exec_inode = bprm->file->f_inode; storage = bpf_inode_storage_get(&inode_storage_map, bprm->file->f_inode, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); if (!storage) return; storage->value = DUMMY_STORAGE_VALUE; } |