49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
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#include "vmlinux.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_kfuncs.h"
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char _license[] SEC("license") = "GPL";
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#ifndef SHA256_DIGEST_SIZE
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#define SHA256_DIGEST_SIZE 32
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#endif
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#define SIZEOF_STRUCT_FSVERITY_DIGEST 4 /* sizeof(struct fsverity_digest) */
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char expected_digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE];
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char digest[SIZEOF_STRUCT_FSVERITY_DIGEST + SHA256_DIGEST_SIZE];
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__u32 monitored_pid;
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__u32 got_fsverity;
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__u32 digest_matches;
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SEC("lsm.s/file_open")
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int BPF_PROG(test_file_open, struct file *f)
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{
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struct bpf_dynptr digest_ptr;
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__u32 pid;
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int ret;
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int i;
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pid = bpf_get_current_pid_tgid() >> 32;
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if (pid != monitored_pid)
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return 0;
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bpf_dynptr_from_mem(digest, sizeof(digest), 0, &digest_ptr);
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ret = bpf_get_fsverity_digest(f, &digest_ptr);
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if (ret < 0)
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return 0;
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got_fsverity = 1;
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for (i = 0; i < (int)sizeof(digest); i++) {
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if (digest[i] != expected_digest[i])
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return 0;
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}
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digest_matches = 1;
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return 0;
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}
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