mirror of https://gitee.com/openkylin/linux.git
bpf: Add bpf_get_attach_cookie() BPF helper to access bpf_cookie value
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs to get access to a user-provided bpf_cookie value, specified during BPF program attachment (BPF link creation) time. Naming is hard, though. With the concept being named "BPF cookie", I've considered calling the helper: - bpf_get_cookie() -- seems too unspecific and easily mistaken with socket cookie; - bpf_get_bpf_cookie() -- too much tautology; - bpf_get_link_cookie() -- would be ok, but while we create a BPF link to attach BPF program to BPF hook, it's still an "attachment" and the bpf_cookie is associated with BPF program attachment to a hook, not a BPF link itself. Technically, we could support bpf_cookie with old-style cgroup programs.So I ultimately rejected it in favor of bpf_get_attach_cookie(). Currently all perf_event-backed BPF program types support bpf_get_attach_cookie() helper. Follow-up patches will add support for fentry/fexit programs as well. While at it, mark bpf_tracing_func_proto() as static to make it obvious that it's only used from within the kernel/trace/bpf_trace.c. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
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@ -2102,9 +2102,6 @@ extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
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extern const struct bpf_func_proto bpf_sk_setsockopt_proto;
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extern const struct bpf_func_proto bpf_sk_getsockopt_proto;
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const struct bpf_func_proto *bpf_tracing_func_proto(
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enum bpf_func_id func_id, const struct bpf_prog *prog);
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const struct bpf_func_proto *tracing_prog_func_proto(
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enum bpf_func_id func_id, const struct bpf_prog *prog);
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@ -4856,6 +4856,21 @@ union bpf_attr {
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* Get address of the traced function (for tracing and kprobe programs).
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* Return
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* Address of the traced function.
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*
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* u64 bpf_get_attach_cookie(void *ctx)
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* Description
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* Get bpf_cookie value provided (optionally) during the program
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* attachment. It might be different for each individual
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* attachment, even if BPF program itself is the same.
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* Expects BPF program context *ctx* as a first argument.
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*
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* Supported for the following program types:
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* - kprobe/uprobe;
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* - tracepoint;
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* - perf_event.
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* Return
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* Value specified by user at BPF link creation/attachment time
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* or 0, if it was not specified.
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*/
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#define __BPF_FUNC_MAPPER(FN) \
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FN(unspec), \
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@ -5032,6 +5047,7 @@ union bpf_attr {
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FN(timer_start), \
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FN(timer_cancel), \
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FN(get_func_ip), \
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FN(get_attach_cookie), \
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/* */
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/* integer value in 'imm' field of BPF_CALL instruction selects which helper
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@ -975,7 +975,34 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
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.arg1_type = ARG_PTR_TO_CTX,
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};
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const struct bpf_func_proto *
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BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
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{
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struct bpf_trace_run_ctx *run_ctx;
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run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
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return run_ctx->bpf_cookie;
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}
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static const struct bpf_func_proto bpf_get_attach_cookie_proto_trace = {
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.func = bpf_get_attach_cookie_trace,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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};
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BPF_CALL_1(bpf_get_attach_cookie_pe, struct bpf_perf_event_data_kern *, ctx)
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{
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return ctx->event->bpf_cookie;
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}
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static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = {
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.func = bpf_get_attach_cookie_pe,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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};
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static const struct bpf_func_proto *
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bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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{
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switch (func_id) {
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@ -1109,6 +1136,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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#endif
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case BPF_FUNC_get_func_ip:
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return &bpf_get_func_ip_proto_kprobe;
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case BPF_FUNC_get_attach_cookie:
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return &bpf_get_attach_cookie_proto_trace;
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default:
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return bpf_tracing_func_proto(func_id, prog);
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}
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@ -1219,6 +1248,8 @@ tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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return &bpf_get_stackid_proto_tp;
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case BPF_FUNC_get_stack:
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return &bpf_get_stack_proto_tp;
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case BPF_FUNC_get_attach_cookie:
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return &bpf_get_attach_cookie_proto_trace;
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default:
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return bpf_tracing_func_proto(func_id, prog);
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}
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@ -1326,6 +1357,8 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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return &bpf_perf_prog_read_value_proto;
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case BPF_FUNC_read_branch_records:
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return &bpf_read_branch_records_proto;
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case BPF_FUNC_get_attach_cookie:
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return &bpf_get_attach_cookie_proto_pe;
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default:
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return bpf_tracing_func_proto(func_id, prog);
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}
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@ -4856,6 +4856,21 @@ union bpf_attr {
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* Get address of the traced function (for tracing and kprobe programs).
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* Return
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* Address of the traced function.
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*
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* u64 bpf_get_attach_cookie(void *ctx)
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* Description
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* Get bpf_cookie value provided (optionally) during the program
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* attachment. It might be different for each individual
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* attachment, even if BPF program itself is the same.
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* Expects BPF program context *ctx* as a first argument.
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*
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* Supported for the following program types:
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* - kprobe/uprobe;
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* - tracepoint;
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* - perf_event.
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* Return
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* Value specified by user at BPF link creation/attachment time
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* or 0, if it was not specified.
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*/
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#define __BPF_FUNC_MAPPER(FN) \
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FN(unspec), \
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@ -5032,6 +5047,7 @@ union bpf_attr {
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FN(timer_start), \
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FN(timer_cancel), \
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FN(get_func_ip), \
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FN(get_attach_cookie), \
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/* */
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/* integer value in 'imm' field of BPF_CALL instruction selects which helper
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