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91e8fa254d
Verify that bpf_ima_inode_hash() returns a non-fresh digest after a file write, and that bpf_ima_file_hash() returns a fresh digest. Verification is done by requesting the digest from the bprm_creds_for_exec hook, called before ima_bprm_check(). Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220302111404.193900-7-roberto.sassu@huawei.com
67 lines
1.2 KiB
C
67 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright 2020 Google LLC.
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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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u32 monitored_pid = 0;
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struct {
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__uint(type, BPF_MAP_TYPE_RINGBUF);
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__uint(max_entries, 1 << 12);
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} ringbuf SEC(".maps");
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char _license[] SEC("license") = "GPL";
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bool use_ima_file_hash;
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bool enable_bprm_creds_for_exec;
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static void ima_test_common(struct file *file)
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{
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u64 ima_hash = 0;
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u64 *sample;
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int ret;
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u32 pid;
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pid = bpf_get_current_pid_tgid() >> 32;
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if (pid == monitored_pid) {
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if (!use_ima_file_hash)
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ret = bpf_ima_inode_hash(file->f_inode, &ima_hash,
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sizeof(ima_hash));
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else
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ret = bpf_ima_file_hash(file, &ima_hash,
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sizeof(ima_hash));
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if (ret < 0 || ima_hash == 0)
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return;
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sample = bpf_ringbuf_reserve(&ringbuf, sizeof(u64), 0);
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if (!sample)
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return;
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*sample = ima_hash;
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bpf_ringbuf_submit(sample, 0);
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}
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return;
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}
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SEC("lsm.s/bprm_committed_creds")
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void BPF_PROG(bprm_committed_creds, struct linux_binprm *bprm)
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{
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ima_test_common(bprm->file);
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}
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SEC("lsm.s/bprm_creds_for_exec")
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int BPF_PROG(bprm_creds_for_exec, struct linux_binprm *bprm)
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{
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if (!enable_bprm_creds_for_exec)
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return 0;
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ima_test_common(bprm->file);
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return 0;
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}
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