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// 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_misc.h"
extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
extern void bpf_key_put(struct bpf_key *key) __ksym;
extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
struct bpf_dynptr *sig_ptr,
struct bpf_key *trusted_keyring) __ksym;
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 4096);
} ringbuf SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, __u32);
} array_map SEC(".maps");
int err, pid;
char _license[] SEC("license") = "GPL";
SEC("?lsm.s/bpf")
__failure __msg("cannot pass in dynptr at an offset=-8")
int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size)
{
unsigned long val;
return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,
(struct bpf_dynptr *)&val, NULL);
}
SEC("?lsm.s/bpf")
__failure __msg("arg#0 expected pointer to stack or const struct bpf_dynptr")
int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size)
{
unsigned long val = 0;
return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,
(struct bpf_dynptr *)val, NULL);
}
SEC("lsm.s/bpf")
int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)
{
struct bpf_key *trusted_keyring;
struct bpf_dynptr ptr;
__u32 *value;
int ret, zero = 0;
if (bpf_get_current_pid_tgid() >> 32 != pid)
return 0;
value = bpf_map_lookup_elem(&array_map, &zero);
if (!value)
return 0;
/* Pass invalid flags. */
ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);
if (ret != -EINVAL)
return 0;
trusted_keyring = bpf_lookup_system_key(0);
if (!trusted_keyring)
return 0;
err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);
bpf_key_put(trusted_keyring);
return 0;
}
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