bpf: Add cookies support for uprobe_multi link

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>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230809083440.3209381-5-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

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;

kernel/bpf/syscall.c

@@ -4882,7 +4882,7 @@ 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;

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
@@ -1104,6 +1106,18 @@ 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;
@@ -1550,9 +1564,11 @@ 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);
 	}
@@ -2978,6 +2994,7 @@ struct bpf_uprobe_multi_link;
 struct bpf_uprobe {
 	struct bpf_uprobe_multi_link *link;
 	loff_t offset;
+	u64 cookie;
 	struct uprobe_consumer consumer;
 };
 
@@ -2991,6 +3008,7 @@ 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,
@@ -3034,6 +3052,7 @@ 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;
@@ -3078,6 +3097,14 @@ 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;
@@ -3086,6 +3113,7 @@ 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;
@@ -3105,7 +3133,7 @@ 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);
@@ -3115,6 +3143,7 @@ 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)) {
@@ -3147,6 +3176,10 @@ 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;
@@ -3202,4 +3235,8 @@ 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 */

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;