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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2020 Google LLC.
*/
#include "vmlinux.h"
#include <errno.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
u32 monitored_pid = 0;
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 1 << 12);
} ringbuf SEC(".maps");
char _license[] SEC("license") = "GPL";
bool use_ima_file_hash;
bool enable_bprm_creds_for_exec;
bool enable_kernel_read_file;
bool test_deny;
static void ima_test_common(struct file *file)
{
u64 ima_hash = 0;
u64 *sample;
int ret;
u32 pid;
pid = bpf_get_current_pid_tgid() >> 32;
if (pid == monitored_pid) {
if (!use_ima_file_hash)
ret = bpf_ima_inode_hash(file->f_inode, &ima_hash,
sizeof(ima_hash));
else
ret = bpf_ima_file_hash(file, &ima_hash,
sizeof(ima_hash));
if (ret < 0 || ima_hash == 0)
return;
sample = bpf_ringbuf_reserve(&ringbuf, sizeof(u64), 0);
if (!sample)
return;
*sample = ima_hash;
bpf_ringbuf_submit(sample, 0);
}
return;
}
static int ima_test_deny(void)
{
u32 pid;
pid = bpf_get_current_pid_tgid() >> 32;
if (pid == monitored_pid && test_deny)
return -EPERM;
return 0;
}
SEC("lsm.s/bprm_committed_creds")
void BPF_PROG(bprm_committed_creds, struct linux_binprm *bprm)
{
ima_test_common(bprm->file);
}
SEC("lsm.s/bprm_creds_for_exec")
int BPF_PROG(bprm_creds_for_exec, struct linux_binprm *bprm)
{
if (!enable_bprm_creds_for_exec)
return 0;
ima_test_common(bprm->file);
return 0;
}
SEC("lsm.s/kernel_read_file")
int BPF_PROG(kernel_read_file, struct file *file, enum kernel_read_file_id id,
bool contents)
{
int ret;
if (!enable_kernel_read_file)
return 0;
if (!contents)
return 0;
if (id != READING_POLICY)
return 0;
ret = ima_test_deny();
if (ret < 0)
return ret;
ima_test_common(file);
return 0;
}
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