Re: [PATCHv5 bpf-next 04/28] bpf: Add cookies support for uprobe_multi link

Yafang Shao
2023-07-31T03:33:42Z

On Sun, Jul 30, 2023 at 9:43 PM Jiri Olsa <jolsa@kernel.org> 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@kernel.org>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

LGTM!
Acked-by: Yafang Shao <laoar.shao@gmail.com>

> ---
> 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 f112a0b948f3..2b6cd7d1c165 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1639,6 +1639,7 @@ union bpf_attr {
> __aligned_u64 path;
> __aligned_u64 offsets;
> __aligned_u64 ref_ctr_offsets;
> + __aligned_u64 cookies;
> __u32 cnt;
> __u32 flags;
> } uprobe_multi;
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 75c83300339e..98459fb34ff7 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -4883,7 +4883,7 @@ 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.flags
> 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 10284fd46f98..d73a47bd2bbd 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);
> }
> @@ -2973,6 +2989,7 @@ struct bpf_uprobe_multi_link;
> struct bpf_uprobe {
> struct bpf_uprobe_multi_link *link;
> loff_t offset;
> + u64 cookie;
> struct uprobe_consumer consumer;
> };
>
> @@ -2986,6 +3003,7 @@ 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,
> @@ -3029,6 +3047,7 @@ 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;
> @@ -3075,6 +3094,14 @@ 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;
> @@ -3083,6 +3110,7 @@ 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;
> @@ -3102,7 +3130,7 @@ 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);
> @@ -3112,6 +3140,7 @@ 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)) {
> @@ -3144,6 +3173,10 @@ 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;
> @@ -3201,4 +3234,8 @@ 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 f112a0b948f3..2b6cd7d1c165 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1639,6 +1639,7 @@ union bpf_attr {
> __aligned_u64 path;
> __aligned_u64 offsets;
> __aligned_u64 ref_ctr_offsets;
> + __aligned_u64 cookies;
> __u32 cnt;
> __u32 flags;
> } uprobe_multi;
> --
> 2.41.0
>

--
Regards
Yafang