// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH * * Author: Roberto Sassu <roberto.sassu@huawei.com> */ #include "vmlinux.h" #include <errno.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> #include "bpf_kfuncs.h" #define MAX_DATA_SIZE (1024 * 1024) #define MAX_SIG_SIZE 1024 __u32 monitored_pid; __u32 user_keyring_serial; __u64 system_keyring_id; struct data { __u8 data[MAX_DATA_SIZE]; __u32 data_len; __u8 sig[MAX_SIG_SIZE]; __u32 sig_len; }; struct { __uint(type, BPF_MAP_TYPE_ARRAY); __uint(max_entries, 1); __type(key, __u32); __type(value, struct data); } data_input SEC(".maps"); char _license[] SEC("license") = "GPL"; SEC("lsm.s/bpf") int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size) { struct bpf_dynptr data_ptr, sig_ptr; struct data *data_val; struct bpf_key *trusted_keyring; __u32 pid; __u64 value; int ret, zero = 0; pid = bpf_get_current_pid_tgid() >> 32; if (pid != monitored_pid) return 0; data_val = bpf_map_lookup_elem(&data_input, &zero); if (!data_val) return 0; ret = bpf_probe_read_kernel(&value, sizeof(value), &attr->value); if (ret) return ret; ret = bpf_copy_from_user(data_val, sizeof(struct data), (void *)(unsigned long)value); if (ret) return ret; if (data_val->data_len > sizeof(data_val->data)) return -EINVAL; bpf_dynptr_from_mem(data_val->data, data_val->data_len, 0, &data_ptr); if (data_val->sig_len > sizeof(data_val->sig)) return -EINVAL; bpf_dynptr_from_mem(data_val->sig, data_val->sig_len, 0, &sig_ptr); if (user_keyring_serial) trusted_keyring = bpf_lookup_user_key(user_keyring_serial, 0); else trusted_keyring = bpf_lookup_system_key(system_keyring_id); if (!trusted_keyring) return -ENOENT; ret = bpf_verify_pkcs7_signature(&data_ptr, &sig_ptr, trusted_keyring); bpf_key_put(trusted_keyring); return ret; }