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1// SPDX-License-Identifier: GPL-2.02 3/*4 * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH5 *6 * Author: Roberto Sassu <roberto.sassu@huawei.com>7 */8 9#include "vmlinux.h"10#include <errno.h>11#include <bpf/bpf_helpers.h>12#include <bpf/bpf_tracing.h>13#include "bpf_misc.h"14 15extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;16extern void bpf_key_put(struct bpf_key *key) __ksym;17extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,18 struct bpf_dynptr *sig_ptr,19 struct bpf_key *trusted_keyring) __ksym;20 21struct {22 __uint(type, BPF_MAP_TYPE_RINGBUF);23 __uint(max_entries, 4096);24} ringbuf SEC(".maps");25 26struct {27 __uint(type, BPF_MAP_TYPE_ARRAY);28 __uint(max_entries, 1);29 __type(key, __u32);30 __type(value, __u32);31} array_map SEC(".maps");32 33int err, pid;34 35char _license[] SEC("license") = "GPL";36 37SEC("?lsm.s/bpf")38__failure __msg("cannot pass in dynptr at an offset=-8")39int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)40{41 unsigned long val;42 43 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,44 (struct bpf_dynptr *)&val, NULL);45}46 47SEC("?lsm.s/bpf")48__failure __msg("arg#1 expected pointer to stack or const struct bpf_dynptr")49int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size)50{51 unsigned long val = 0;52 53 return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,54 (struct bpf_dynptr *)val, NULL);55}56 57SEC("lsm.s/bpf")58int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)59{60 struct bpf_key *trusted_keyring;61 struct bpf_dynptr ptr;62 __u32 *value;63 int ret, zero = 0;64 65 if (bpf_get_current_pid_tgid() >> 32 != pid)66 return 0;67 68 value = bpf_map_lookup_elem(&array_map, &zero);69 if (!value)70 return 0;71 72 /* Pass invalid flags. */73 ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);74 if (ret != -EINVAL)75 return 0;76 77 trusted_keyring = bpf_lookup_system_key(0);78 if (!trusted_keyring)79 return 0;80 81 err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);82 83 bpf_key_put(trusted_keyring);84 85 return 0;86}87