87 lines
2.0 KiB
C
87 lines
2.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
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*
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* Author: Roberto Sassu <roberto.sassu@huawei.com>
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*/
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#include "vmlinux.h"
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#include <errno.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "bpf_misc.h"
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extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
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extern void bpf_key_put(struct bpf_key *key) __ksym;
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extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
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struct bpf_dynptr *sig_ptr,
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struct bpf_key *trusted_keyring) __ksym;
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struct {
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__uint(type, BPF_MAP_TYPE_RINGBUF);
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__uint(max_entries, 4096);
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} ringbuf SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__uint(max_entries, 1);
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__type(key, __u32);
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__type(value, __u32);
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} array_map SEC(".maps");
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int err, pid;
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char _license[] SEC("license") = "GPL";
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SEC("?lsm.s/bpf")
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__failure __msg("cannot pass in dynptr at an offset=-8")
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int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)
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{
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unsigned long val;
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return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,
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(struct bpf_dynptr *)&val, NULL);
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}
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SEC("?lsm.s/bpf")
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__failure __msg("arg#0 expected pointer to stack or dynptr_ptr")
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int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size)
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{
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unsigned long val;
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return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,
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(struct bpf_dynptr *)val, NULL);
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}
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SEC("lsm.s/bpf")
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int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)
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{
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struct bpf_key *trusted_keyring;
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struct bpf_dynptr ptr;
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__u32 *value;
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int ret, zero = 0;
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return 0;
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value = bpf_map_lookup_elem(&array_map, &zero);
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if (!value)
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return 0;
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/* Pass invalid flags. */
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ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);
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if (ret != -EINVAL)
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return 0;
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trusted_keyring = bpf_lookup_system_key(0);
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if (!trusted_keyring)
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return 0;
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err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);
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bpf_key_put(trusted_keyring);
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return 0;
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}
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