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// SPDX-License-Identifier: GPL-2.0-only
#include "vmlinux.h"
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
char _license[] SEC("license") = "GPL";
#define EPERM 1 /* Operation not permitted */
/* From include/linux/mm.h. */
#define FMODE_WRITE 0x2
struct map;
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, __u32);
__type(value, __u32);
__uint(max_entries, 1);
} prot_status_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, __u32);
__type(value, __u32);
__uint(max_entries, 3);
} prot_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, __u32);
__type(value, __u32);
__uint(max_entries, 3);
} not_prot_map SEC(".maps");
SEC("fmod_ret/security_bpf_map")
int BPF_PROG(fmod_bpf_map, struct bpf_map *map, int fmode)
{
__u32 key = 0;
__u32 *status_ptr = bpf_map_lookup_elem(&prot_status_map, &key);
if (!status_ptr || !*status_ptr)
return 0;
if (map == &prot_map) {
/* Allow read-only access */
if (fmode & FMODE_WRITE)
return -EPERM;
}
return 0;
}
/*
* This program keeps references to maps. This is needed to prevent
* optimizing them out.
*/
SEC("fentry/bpf_fentry_test1")
int BPF_PROG(fentry_dummy1, int a)
{
__u32 key = 0;
__u32 val1 = a;
__u32 val2 = a + 1;
bpf_map_update_elem(&prot_map, &key, &val1, BPF_ANY);
bpf_map_update_elem(¬_prot_map, &key, &val2, BPF_ANY);
return 0;
}
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