[PATCH bpf-next 09/17] bpf: Add support for tracing_multi link cookies

[Jiri Olsa <jolsa@kernel.org>]

Add support to specify cookies for tracing_multi link.

Cookies are provided in array where each value is paired with provided
BTF ID value with the same array index.

Such cookie can be retrieved by bpf program with bpf_get_attach_cookie
helper call.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h            |  1 +
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/trampoline.c        |  1 +
 kernel/trace/bpf_trace.c       | 18 ++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  1 +
 5 files changed, 22 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 00585693d31a..63a06c85103b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1901,6 +1901,7 @@ struct bpf_tracing_multi_node {
 
 struct bpf_tracing_multi_link {
 	struct bpf_link link;
+	u64 *cookies;
 	int nodes_cnt;
 	struct bpf_tracing_multi_node nodes[] __counted_by(nodes_cnt);
 };
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7f5c51f27a36..e28722ddeb5b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1866,6 +1866,7 @@ union bpf_attr {
 			} cgroup;
 			struct {
 				__aligned_u64	ids;
+				__aligned_u64	cookies;
 				__u32		cnt;
 			} tracing_multi;
 		};
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index c32205adfebe..516c27b89701 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -1546,6 +1546,7 @@ int bpf_trampoline_multi_attach(struct bpf_prog *prog, u32 *ids,
 
 		mnode->trampoline = tr;
 		mnode->node.link = &link->link;
+		mnode->node.cookie = link->cookies ? link->cookies[i] : 0;
 	}
 
 	trampoline_lock_all();
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index bfae9ec5d1b1..927fa622c5ea 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3609,6 +3609,7 @@ static void bpf_tracing_multi_link_dealloc(struct bpf_link *link)
 	struct bpf_tracing_multi_link *tr_link =
 		container_of(link, struct bpf_tracing_multi_link, link);
 
+	kvfree(tr_link->cookies);
 	kfree(tr_link);
 }
 
@@ -3622,6 +3623,8 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
 	struct bpf_tracing_multi_link *link = NULL;
 	struct bpf_link_primer link_primer;
 	u32 cnt, *ids = NULL;
+	u64 *cookies = NULL;
+	void __user *ucookies;
 	u32 __user *uids;
 	int err;
 
@@ -3642,6 +3645,19 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
 		goto error;
 	}
 
+	ucookies = u64_to_user_ptr(attr->link_create.tracing_multi.cookies);
+	if (ucookies) {
+		cookies = kvmalloc_array(cnt, sizeof(*cookies), GFP_KERNEL);
+		if (!cookies) {
+			err = -ENOMEM;
+			goto error;
+		}
+		if (copy_from_user(cookies, ucookies, cnt * sizeof(*cookies))) {
+			err = -EFAULT;
+			goto error;
+		}
+	}
+
 	link = kzalloc(struct_size(link, nodes, cnt), GFP_KERNEL);
 	if (!link) {
 		err = -ENOMEM;
@@ -3656,6 +3672,7 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
 		goto error;
 
 	link->nodes_cnt = cnt;
+	link->cookies = cookies;
 
 	err = bpf_trampoline_multi_attach(prog, ids, link);
 	kvfree(ids);
@@ -3666,6 +3683,7 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
 	return bpf_link_settle(&link_primer);
 
 error:
+	kvfree(cookies);
 	kvfree(ids);
 	kfree(link);
 	return err;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7f5c51f27a36..e28722ddeb5b 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1866,6 +1866,7 @@ union bpf_attr {
 			} cgroup;
 			struct {
 				__aligned_u64	ids;
+				__aligned_u64	cookies;
 				__u32		cnt;
 			} tracing_multi;
 		};
-- 
2.52.0