On Fri, Jun 30, 2023 at 4:34 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding support to specify cookies array for uprobe_multi link.
>
> The cookies array share indexes and length with other uprobe_multi
> arrays (offsets/ref_ctr_offsets).
>
> The cookies[i] value defines cookie for i-the uprobe and will be
> returned by bpf_get_attach_cookie helper when called from ebpf
> program hooked to that specific uprobe.
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 1 +
> kernel/bpf/syscall.c | 2 +-
> kernel/trace/bpf_trace.c | 45 +++++++++++++++++++++++++++++++---
> tools/include/uapi/linux/bpf.h | 1 +
> 4 files changed, 44 insertions(+), 5 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index a236139f08ce..4103f395593b 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1592,6 +1592,7 @@ union bpf_attr {
> __aligned_u64 path;
> __aligned_u64 offsets;
> __aligned_u64 ref_ctr_offsets;
> + __aligned_u64 cookies;
Could you pls. explain why the 'cookies' is defined as a pointer ? Are
there real use cases to define different cookies for different probes
in a single uprobe_multi ? Why can't we just use one cookie for all
probes? Per my understanding, the cookie is used to identify the user
or the application, rather than each probe.
We also defined it the same way in kprobe_multi...
> } uprobe_multi;
> };
> } link_create;
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 3b0582a64ce4..affad356c603 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -4680,7 +4680,7 @@ static int bpf_map_do_batch(const union bpf_attr *attr,
> return err;
> }
>
> -#define BPF_LINK_CREATE_LAST_FIELD link_create.kprobe_multi.cookies
> +#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.cookies
> static int link_create(union bpf_attr *attr, bpfptr_t uattr)
> {
> struct bpf_prog *prog;
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index a0b9d034300f..4657df8f884e 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -87,6 +87,8 @@ static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
> static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx);
> static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx);
>
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx);
> +
> /**
> * trace_call_bpf - invoke BPF program
> * @call: tracepoint event
> @@ -1099,6 +1101,18 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto_kmulti = {
> .arg1_type = ARG_PTR_TO_CTX,
> };
>
> +BPF_CALL_1(bpf_get_attach_cookie_uprobe_multi, struct pt_regs *, regs)
> +{
> + return bpf_uprobe_multi_cookie(current->bpf_ctx);
> +}
> +
> +static const struct bpf_func_proto bpf_get_attach_cookie_proto_umulti = {
> + .func = bpf_get_attach_cookie_uprobe_multi,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
> {
> struct bpf_trace_run_ctx *run_ctx;
> @@ -1545,9 +1559,11 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> &bpf_get_func_ip_proto_kprobe_multi :
> &bpf_get_func_ip_proto_kprobe;
> case BPF_FUNC_get_attach_cookie:
> - return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
> - &bpf_get_attach_cookie_proto_kmulti :
> - &bpf_get_attach_cookie_proto_trace;
> + if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI)
> + return &bpf_get_attach_cookie_proto_kmulti;
> + if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI)
> + return &bpf_get_attach_cookie_proto_umulti;
> + return &bpf_get_attach_cookie_proto_trace;
> default:
> return bpf_tracing_func_proto(func_id, prog);
> }
> @@ -2930,6 +2946,7 @@ struct bpf_uprobe_multi_link;
> struct bpf_uprobe {
> struct bpf_uprobe_multi_link *link;
> loff_t offset;
> + u64 cookie;
> struct uprobe_consumer consumer;
> };
>
> @@ -2943,6 +2960,7 @@ struct bpf_uprobe_multi_link {
> struct bpf_uprobe_multi_run_ctx {
> struct bpf_run_ctx run_ctx;
> unsigned long entry_ip;
> + struct bpf_uprobe *uprobe;
> };
>
> static void bpf_uprobe_unregister(struct path *path, struct bpf_uprobe *uprobes,
> @@ -2986,6 +3004,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
> struct bpf_uprobe_multi_link *link = uprobe->link;
> struct bpf_uprobe_multi_run_ctx run_ctx = {
> .entry_ip = entry_ip,
> + .uprobe = uprobe,
> };
> struct bpf_prog *prog = link->link.prog;
> bool sleepable = prog->aux->sleepable;
> @@ -3032,6 +3051,14 @@ uprobe_multi_link_ret_handler(struct uprobe_consumer *con, unsigned long func, s
> return uprobe_prog_run(uprobe, func, regs);
> }
>
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
> +{
> + struct bpf_uprobe_multi_run_ctx *run_ctx;
> +
> + run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx, run_ctx);
> + return run_ctx->uprobe->cookie;
> +}
> +
> int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
> {
> struct bpf_uprobe_multi_link *link = NULL;
> @@ -3040,6 +3067,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> struct bpf_link_primer link_primer;
> struct bpf_uprobe *uprobes = NULL;
> unsigned long __user *uoffsets;
> + u64 __user *ucookies;
> void __user *upath;
> u32 flags, cnt, i;
> struct path path;
> @@ -3059,7 +3087,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>
> /*
> * path, offsets and cnt are mandatory,
> - * ref_ctr_offsets is optional
> + * ref_ctr_offsets and cookies are optional
> */
> upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
> uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
> @@ -3069,6 +3097,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> return -EINVAL;
>
> uref_ctr_offsets = u64_to_user_ptr(attr->link_create.uprobe_multi.ref_ctr_offsets);
> + ucookies = u64_to_user_ptr(attr->link_create.uprobe_multi.cookies);
>
> name = strndup_user(upath, PATH_MAX);
> if (IS_ERR(name)) {
> @@ -3101,6 +3130,10 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> }
>
> for (i = 0; i < cnt; i++) {
> + if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) {
> + err = -EFAULT;
> + goto error_free;
> + }
> if (uref_ctr_offsets && __get_user(ref_ctr_offsets[i], uref_ctr_offsets + i)) {
> err = -EFAULT;
> goto error_free;
> @@ -3158,4 +3191,8 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> {
> return -EOPNOTSUPP;
> }
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
> +{
> + return 0;
> +}
> #endif /* CONFIG_UPROBES */
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index a236139f08ce..4103f395593b 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1592,6 +1592,7 @@ union bpf_attr {
> __aligned_u64 path;
> __aligned_u64 offsets;
> __aligned_u64 ref_ctr_offsets;
> + __aligned_u64 cookies;
> } uprobe_multi;
> };
> } link_create;
> --
> 2.41.0
>
>
--
Regards
Yafang
