c6bde958a6
Currently key_size of hashtab is limited to MAX_BPF_STACK. As the key of hashtab can also be a value from a per cpu map it can be larger than MAX_BPF_STACK. The use-case for this patch originates to implement allow/disallow lists for files and file paths. The maximum length of file paths is defined by PATH_MAX with 4096 chars including nul. This limit exceeds MAX_BPF_STACK. Changelog: v5: - Fix cast overflow v4: - Utilize BPF skeleton in tests - Rebase v3: - Rebase v2: - Add a test for bpf side Signed-off-by: Florian Lehner <dev@der-flo.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201029201442.596690-1-dev@der-flo.net
45 lines
802 B
C
45 lines
802 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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char _license[] SEC("license") = "GPL";
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 2);
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__type(key, struct bigelement);
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__type(value, __u32);
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} hash_map SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__uint(max_entries, 1);
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__type(key, __u32);
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__type(value, struct bigelement);
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} key_map SEC(".maps");
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struct bigelement {
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int a;
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char b[4096];
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long long c;
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};
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SEC("raw_tracepoint/sys_enter")
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int bpf_hash_large_key_test(void *ctx)
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{
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int zero = 0, err = 1, value = 42;
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struct bigelement *key;
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key = bpf_map_lookup_elem(&key_map, &zero);
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if (!key)
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return 0;
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key->c = 1;
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if (bpf_map_update_elem(&hash_map, key, &value, BPF_ANY))
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return 0;
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return 0;
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}
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