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selftest/bpf: Add a test that reads various addresses.

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Add a function to bpf_testmod that returns invalid kernel and user addresses.
Then attach an fexit program to that function that tries to read
memory through these addresses.

This logic checks that bpf_probe_read_kernel and BPF_PROBE_MEM logic is sane.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Alexei Starovoitov
2021-12-15 12:35:34 -08:00
committed by Daniel Borkmann
parent 588a25e924
commit 7edc3fcbf9
2 changed files with 32 additions and 0 deletions
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12
tools/testing/selftests/bpf/progs/test_module_attach.c
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@@ -87,6 +87,18 @@ int BPF_PROG(handle_fexit,
return 0;
}
SEC("fexit/bpf_testmod_return_ptr")
int BPF_PROG(handle_fexit_ret, int arg, struct file *ret)
{
long buf = 0;
bpf_probe_read_kernel(&buf, 8, ret);
bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);
*(volatile long long *)ret;
*(volatile int *)&ret->f_mode;
return 0;
}
__u32 fmod_ret_read_sz = 0;
SEC("fmod_ret/bpf_testmod_test_read")