bpf: Store cookies in kprobe_multi bpf_link_info data

Storing cookies in kprobe_multi bpf_link_info data. The cookies
field is optional and if provided it needs to be an array of
__u64 with kprobe_multi.count length.

Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 181e74433272915f64305631e6d483161d00e44a..287d05732668fc8c442f631c90d7227bc77751af 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6563,6 +6563,7 @@ struct bpf_link_info {
                        __u32 count; /* in/out: kprobe_multi function count */
                        __u32 flags;
                        __u64 missed;
+                       __aligned_u64 cookies;
                } kprobe_multi;
                struct {
                        __aligned_u64 path;

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 7ac6c52b25ebc8dcb93df83844f5e796740b8206..c98c20abaf99d2dc49064ea37ca03c80d07f26d2 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2679,6 +2679,7 @@ static void bpf_kprobe_multi_link_dealloc(struct bpf_link *link)
 static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
                                                struct bpf_link_info *info)
 {
+       u64 __user *ucookies = u64_to_user_ptr(info->kprobe_multi.cookies);
        u64 __user *uaddrs = u64_to_user_ptr(info->kprobe_multi.addrs);
        struct bpf_kprobe_multi_link *kmulti_link;
        u32 ucount = info->kprobe_multi.count;
@@ -2686,6 +2687,8 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 
        if (!uaddrs ^ !ucount)
                return -EINVAL;
+       if (ucookies && !ucount)
+               return -EINVAL;
 
        kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
        info->kprobe_multi.count = kmulti_link->cnt;
@@ -2699,6 +2702,18 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
        else
                ucount = kmulti_link->cnt;
 
+       if (ucookies) {
+               if (kmulti_link->cookies) {
+                       if (copy_to_user(ucookies, kmulti_link->cookies, ucount * sizeof(u64)))
+                               return -EFAULT;
+               } else {
+                       for (i = 0; i < ucount; i++) {
+                               if (put_user(0, ucookies + i))
+                                       return -EFAULT;
+                       }
+               }
+       }
+
        if (kallsyms_show_value(current_cred())) {
                if (copy_to_user(uaddrs, kmulti_link->addrs, ucount * sizeof(u64)))
                        return -EFAULT;

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 181e74433272915f64305631e6d483161d00e44a..287d05732668fc8c442f631c90d7227bc77751af 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6563,6 +6563,7 @@ struct bpf_link_info {
                        __u32 count; /* in/out: kprobe_multi function count */
                        __u32 flags;
                        __u64 missed;
+                       __aligned_u64 cookies;
                } kprobe_multi;
                struct {
                        __aligned_u64 path;