On Mon, Jun 12, 2023 at 03:15:59PM +0000, Yafang Shao wrote:
SNIP
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 2bc41e6..742047c 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2548,9 +2548,36 @@ static void bpf_kprobe_multi_link_dealloc(struct bpf_link *link)
> kfree(kmulti_link);
> }
>
> +static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
> + struct bpf_link_info *info)
> +{
> + u64 __user *uaddrs = u64_to_user_ptr(info->kprobe_multi.addrs);
> + struct bpf_kprobe_multi_link *kmulti_link;
> + u32 ucount = info->kprobe_multi.count;
> +
> + if (!uaddrs ^ !ucount)
> + return -EINVAL;
> +
> + kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
> + if (!uaddrs) {
> + info->kprobe_multi.count = kmulti_link->cnt;
> + return 0;
> + }
> +
> + if (ucount < kmulti_link->cnt)
> + return -EINVAL;
> + info->kprobe_multi.flags = kmulti_link->fp.flags;
> + if (!kallsyms_show_value(current_cred()))
> + return 0;
> + if (copy_to_user(uaddrs, kmulti_link->addrs, ucount * sizeof(u64)))
> + return -EFAULT;
> + return 0;
> +}
> +
> static const struct bpf_link_ops bpf_kprobe_multi_link_lops = {
> .release = bpf_kprobe_multi_link_release,
> .dealloc = bpf_kprobe_multi_link_dealloc,
> + .fill_link_info = bpf_kprobe_multi_link_fill_link_info,
> };
>
> static void bpf_kprobe_multi_cookie_swap(void *a, void *b, int size, const void *priv)
> @@ -2890,6 +2917,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> return err;
> }
>
> + link->fp.flags = flags;
hum this looks wrong, we can't use fprobe flags to store our flags
you should add flags to bpf_kprobe_multi_link
jirka
> return bpf_link_settle(&link_primer);
>
> error:
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index a7b5e91..23691ea 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -6438,6 +6438,11 @@ struct bpf_link_info {
> __s32 priority;
> __u32 flags;
> } netfilter;
> + struct {
> + __aligned_u64 addrs; /* in/out: addresses buffer ptr */
> + __u32 count;
> + __u32 flags;
> + } kprobe_multi;
> };
> } __attribute__((aligned(8)));
>
> --
> 1.8.3.1
>
