Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2021-06-28

The following pull-request contains BPF updates for your *net-next* tree.

We've added 37 non-merge commits during the last 12 day(s) which contain
a total of 56 files changed, 394 insertions(+), 380 deletions(-).

The main changes are:

1) XDP driver RCU cleanups, from Toke Høiland-Jørgensen and Paul E. McKenney.

2) Fix bpf_skb_change_proto() IPv4/v6 GSO handling, from Maciej Żenczykowski.

3) Fix false positive kmemleak report for BPF ringbuf alloc, from Rustam Kovhaev.

4) Fix x86 JIT's extable offset calculation for PROBE_LDX NULL, from Ravi Bangoria.

5) Enable libbpf fallback probing with tracing under RHEL7, from Jonathan Edwards.

6) Clean up x86 JIT to remove unused cnt tracking from EMIT macro, from Jiri Olsa.

7) Netlink cleanups for libbpf to please Coverity, from Kumar Kartikeya Dwivedi.

8) Allow to retrieve ancestor cgroup id in tracing programs, from Namhyung Kim.

9) Fix lirc BPF program query to use user-provided prog_cnt, from Sean Young.

10) Add initial libbpf doc including generated kdoc for its API, from Grant Seltzer.

11) Make xdp_rxq_info_unreg_mem_model() more robust, from Jakub Kicinski.

12) Fix up bpfilter startup log-level to info level, from Gary Lin.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 73 insertions, 254 deletions

diff --git a/tools/lib/bpf/README.rst b/tools/lib/bpf/README.rst
deleted file mode 100644
index 8928f7787f2d..000000000000
--- a/tools/lib/bpf/README.rst
+++ /dev/null
@@ -1,168 +0,0 @@
-.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
-
-libbpf API naming convention
-============================
-
-libbpf API provides access to a few logically separated groups of
-functions and types. Every group has its own naming convention
-described here. It's recommended to follow these conventions whenever a
-new function or type is added to keep libbpf API clean and consistent.
-
-All types and functions provided by libbpf API should have one of the
-following prefixes: ``bpf_``, ``btf_``, ``libbpf_``, ``xsk_``,
-``perf_buffer_``.
-
-System call wrappers
---------------------
-
-System call wrappers are simple wrappers for commands supported by
-sys_bpf system call. These wrappers should go to ``bpf.h`` header file
-and map one-on-one to corresponding commands.
-
-For example ``bpf_map_lookup_elem`` wraps ``BPF_MAP_LOOKUP_ELEM``
-command of sys_bpf, ``bpf_prog_attach`` wraps ``BPF_PROG_ATTACH``, etc.
-
-Objects
--------
-
-Another class of types and functions provided by libbpf API is "objects"
-and functions to work with them. Objects are high-level abstractions
-such as BPF program or BPF map. They're represented by corresponding
-structures such as ``struct bpf_object``, ``struct bpf_program``,
-``struct bpf_map``, etc.
-
-Structures are forward declared and access to their fields should be
-provided via corresponding getters and setters rather than directly.
-
-These objects are associated with corresponding parts of ELF object that
-contains compiled BPF programs.
-
-For example ``struct bpf_object`` represents ELF object itself created
-from an ELF file or from a buffer, ``struct bpf_program`` represents a
-program in ELF object and ``struct bpf_map`` is a map.
-
-Functions that work with an object have names built from object name,
-double underscore and part that describes function purpose.
-
-For example ``bpf_object__open`` consists of the name of corresponding
-object, ``bpf_object``, double underscore and ``open`` that defines the
-purpose of the function to open ELF file and create ``bpf_object`` from
-it.
-
-Another example: ``bpf_program__load`` is named for corresponding
-object, ``bpf_program``, that is separated from other part of the name
-by double underscore.
-
-All objects and corresponding functions other than BTF related should go
-to ``libbpf.h``. BTF types and functions should go to ``btf.h``.
-
-Auxiliary functions
--------------------
-
-Auxiliary functions and types that don't fit well in any of categories
-described above should have ``libbpf_`` prefix, e.g.
-``libbpf_get_error`` or ``libbpf_prog_type_by_name``.
-
-AF_XDP functions
--------------------
-
-AF_XDP functions should have an ``xsk_`` prefix, e.g.
-``xsk_umem__get_data`` or ``xsk_umem__create``. The interface consists
-of both low-level ring access functions and high-level configuration
-functions. These can be mixed and matched. Note that these functions
-are not reentrant for performance reasons.
-
-Please take a look at Documentation/networking/af_xdp.rst in the Linux
-kernel source tree on how to use XDP sockets and for some common
-mistakes in case you do not get any traffic up to user space.
-
-libbpf ABI
-==========
-
-libbpf can be both linked statically or used as DSO. To avoid possible
-conflicts with other libraries an application is linked with, all
-non-static libbpf symbols should have one of the prefixes mentioned in
-API documentation above. See API naming convention to choose the right
-name for a new symbol.
-
-Symbol visibility
------------------
-
-libbpf follow the model when all global symbols have visibility "hidden"
-by default and to make a symbol visible it has to be explicitly
-attributed with ``LIBBPF_API`` macro. For example:
-
-.. code-block:: c
-
-        LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);
-
-This prevents from accidentally exporting a symbol, that is not supposed
-to be a part of ABI what, in turn, improves both libbpf developer- and
-user-experiences.
-
-ABI versionning
----------------
-
-To make future ABI extensions possible libbpf ABI is versioned.
-Versioning is implemented by ``libbpf.map`` version script that is
-passed to linker.
-
-Version name is ``LIBBPF_`` prefix + three-component numeric version,
-starting from ``0.0.1``.
-
-Every time ABI is being changed, e.g. because a new symbol is added or
-semantic of existing symbol is changed, ABI version should be bumped.
-This bump in ABI version is at most once per kernel development cycle.
-
-For example, if current state of ``libbpf.map`` is:
-
-.. code-block::
-        LIBBPF_0.0.1 {
-        	global:
-                        bpf_func_a;
-                        bpf_func_b;
-        	local:
-        		\*;
-        };
-
-, and a new symbol ``bpf_func_c`` is being introduced, then
-``libbpf.map`` should be changed like this:
-
-.. code-block::
-        LIBBPF_0.0.1 {
-        	global:
-                        bpf_func_a;
-                        bpf_func_b;
-        	local:
-        		\*;
-        };
-        LIBBPF_0.0.2 {
-                global:
-                        bpf_func_c;
-        } LIBBPF_0.0.1;
-
-, where new version ``LIBBPF_0.0.2`` depends on the previous
-``LIBBPF_0.0.1``.
-
-Format of version script and ways to handle ABI changes, including
-incompatible ones, described in details in [1].
-
-Stand-alone build
-=================
-
-Under https://github.com/libbpf/libbpf there is a (semi-)automated
-mirror of the mainline's version of libbpf for a stand-alone build.
-
-However, all changes to libbpf's code base must be upstreamed through
-the mainline kernel tree.
-
-License
-=======
-
-libbpf is dual-licensed under LGPL 2.1 and BSD 2-Clause.
-
-Links
-=====
-
-[1] https://www.akkadia.org/drepper/dsohowto.pdf
-    (Chapter 3. Maintaining APIs and ABIs).
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 48c0ade05ab1..1e04ce724240 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4001,6 +4001,10 @@ bpf_object__probe_loading(struct bpf_object *obj)
 
 	ret = bpf_load_program_xattr(&attr, NULL, 0);
 	if (ret < 0) {
+		attr.prog_type = BPF_PROG_TYPE_TRACEPOINT;
+		ret = bpf_load_program_xattr(&attr, NULL, 0);
+	}
+	if (ret < 0) {
 		ret = errno;
 		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
 		pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index cf9381f03b16..39f25e09b51e 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -154,7 +154,7 @@ done:
 	return ret;
 }
 
-static int libbpf_netlink_send_recv(struct nlmsghdr *nh,
+static int libbpf_netlink_send_recv(struct libbpf_nla_req *req,
 				    __dump_nlmsg_t parse_msg,
 				    libbpf_dump_nlmsg_t parse_attr,
 				    void *cookie)
@@ -166,15 +166,15 @@ static int libbpf_netlink_send_recv(struct nlmsghdr *nh,
 	if (sock < 0)
 		return sock;
 
-	nh->nlmsg_pid = 0;
-	nh->nlmsg_seq = time(NULL);
+	req->nh.nlmsg_pid = 0;
+	req->nh.nlmsg_seq = time(NULL);
 
-	if (send(sock, nh, nh->nlmsg_len, 0) < 0) {
+	if (send(sock, req, req->nh.nlmsg_len, 0) < 0) {
 		ret = -errno;
 		goto out;
 	}
 
-	ret = libbpf_netlink_recv(sock, nl_pid, nh->nlmsg_seq,
+	ret = libbpf_netlink_recv(sock, nl_pid, req->nh.nlmsg_seq,
 				  parse_msg, parse_attr, cookie);
 out:
 	libbpf_netlink_close(sock);
@@ -186,11 +186,7 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
 {
 	struct nlattr *nla;
 	int ret;
-	struct {
-		struct nlmsghdr  nh;
-		struct ifinfomsg ifinfo;
-		char             attrbuf[64];
-	} req;
+	struct libbpf_nla_req req;
 
 	memset(&req, 0, sizeof(req));
 	req.nh.nlmsg_len      = NLMSG_LENGTH(sizeof(struct ifinfomsg));
@@ -199,27 +195,26 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
 	req.ifinfo.ifi_family = AF_UNSPEC;
 	req.ifinfo.ifi_index  = ifindex;
 
-	nla = nlattr_begin_nested(&req.nh, sizeof(req), IFLA_XDP);
+	nla = nlattr_begin_nested(&req, IFLA_XDP);
 	if (!nla)
 		return -EMSGSIZE;
-	ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_FD, &fd, sizeof(fd));
+	ret = nlattr_add(&req, IFLA_XDP_FD, &fd, sizeof(fd));
 	if (ret < 0)
 		return ret;
 	if (flags) {
-		ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_FLAGS, &flags,
-				 sizeof(flags));
+		ret = nlattr_add(&req, IFLA_XDP_FLAGS, &flags, sizeof(flags));
 		if (ret < 0)
 			return ret;
 	}
 	if (flags & XDP_FLAGS_REPLACE) {
-		ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_EXPECTED_FD,
-				 &old_fd, sizeof(old_fd));
+		ret = nlattr_add(&req, IFLA_XDP_EXPECTED_FD, &old_fd,
+				 sizeof(old_fd));
 		if (ret < 0)
 			return ret;
 	}
-	nlattr_end_nested(&req.nh, nla);
+	nlattr_end_nested(&req, nla);
 
-	return libbpf_netlink_send_recv(&req.nh, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
 }
 
 int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,
@@ -314,14 +309,11 @@ int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
 	struct xdp_id_md xdp_id = {};
 	__u32 mask;
 	int ret;
-	struct {
-		struct nlmsghdr  nh;
-		struct ifinfomsg ifm;
-	} req = {
-		.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
-		.nh.nlmsg_type  = RTM_GETLINK,
-		.nh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
-		.ifm.ifi_family = AF_PACKET,
+	struct libbpf_nla_req req = {
+		.nh.nlmsg_len      = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.nh.nlmsg_type     = RTM_GETLINK,
+		.nh.nlmsg_flags    = NLM_F_DUMP | NLM_F_REQUEST,
+		.ifinfo.ifi_family = AF_PACKET,
 	};
 
 	if (flags & ~XDP_FLAGS_MASK || !info_size)
@@ -336,7 +328,7 @@ int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
 	xdp_id.ifindex = ifindex;
 	xdp_id.flags = flags;
 
-	ret = libbpf_netlink_send_recv(&req.nh, __dump_link_nlmsg,
+	ret = libbpf_netlink_send_recv(&req, __dump_link_nlmsg,
 				       get_xdp_info, &xdp_id);
 	if (!ret) {
 		size_t sz = min(info_size, sizeof(xdp_id.info));
@@ -376,15 +368,14 @@ int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
 	return libbpf_err(ret);
 }
 
-typedef int (*qdisc_config_t)(struct nlmsghdr *nh, struct tcmsg *t,
-			      size_t maxsz);
+typedef int (*qdisc_config_t)(struct libbpf_nla_req *req);
 
-static int clsact_config(struct nlmsghdr *nh, struct tcmsg *t, size_t maxsz)
+static int clsact_config(struct libbpf_nla_req *req)
 {
-	t->tcm_parent = TC_H_CLSACT;
-	t->tcm_handle = TC_H_MAKE(TC_H_CLSACT, 0);
+	req->tc.tcm_parent = TC_H_CLSACT;
+	req->tc.tcm_handle = TC_H_MAKE(TC_H_CLSACT, 0);
 
-	return nlattr_add(nh, maxsz, TCA_KIND, "clsact", sizeof("clsact"));
+	return nlattr_add(req, TCA_KIND, "clsact", sizeof("clsact"));
 }
 
 static int attach_point_to_config(struct bpf_tc_hook *hook,
@@ -431,11 +422,7 @@ static int tc_qdisc_modify(struct bpf_tc_hook *hook, int cmd, int flags)
 {
 	qdisc_config_t config;
 	int ret;
-	struct {
-		struct nlmsghdr nh;
-		struct tcmsg tc;
-		char buf[256];
-	} req;
+	struct libbpf_nla_req req;
 
 	ret = attach_point_to_config(hook, &config);
 	if (ret < 0)
@@ -448,11 +435,11 @@ static int tc_qdisc_modify(struct bpf_tc_hook *hook, int cmd, int flags)
 	req.tc.tcm_family  = AF_UNSPEC;
 	req.tc.tcm_ifindex = OPTS_GET(hook, ifindex, 0);
 
-	ret = config(&req.nh, &req.tc, sizeof(req));
+	ret = config(&req);
 	if (ret < 0)
 		return ret;
 
-	return libbpf_netlink_send_recv(&req.nh, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
 }
 
 static int tc_qdisc_create_excl(struct bpf_tc_hook *hook)
@@ -537,14 +524,14 @@ static int get_tc_info(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,
 	struct nlattr *tb[TCA_MAX + 1];
 
 	libbpf_nla_parse(tb, TCA_MAX,
-			 (struct nlattr *)((char *)tc + NLMSG_ALIGN(sizeof(*tc))),
+			 (struct nlattr *)((void *)tc + NLMSG_ALIGN(sizeof(*tc))),
 			 NLMSG_PAYLOAD(nh, sizeof(*tc)), NULL);
 	if (!tb[TCA_KIND])
 		return NL_CONT;
 	return __get_tc_info(cookie, tc, tb, nh->nlmsg_flags & NLM_F_ECHO);
 }
 
-static int tc_add_fd_and_name(struct nlmsghdr *nh, size_t maxsz, int fd)
+static int tc_add_fd_and_name(struct libbpf_nla_req *req, int fd)
 {
 	struct bpf_prog_info info = {};
 	__u32 info_len = sizeof(info);
@@ -555,7 +542,7 @@ static int tc_add_fd_and_name(struct nlmsghdr *nh, size_t maxsz, int fd)
 	if (ret < 0)
 		return ret;
 
-	ret = nlattr_add(nh, maxsz, TCA_BPF_FD, &fd, sizeof(fd));
+	ret = nlattr_add(req, TCA_BPF_FD, &fd, sizeof(fd));
 	if (ret < 0)
 		return ret;
 	len = snprintf(name, sizeof(name), "%s:[%u]", info.name, info.id);
@@ -563,7 +550,7 @@ static int tc_add_fd_and_name(struct nlmsghdr *nh, size_t maxsz, int fd)
 		return -errno;
 	if (len >= sizeof(name))
 		return -ENAMETOOLONG;
-	return nlattr_add(nh, maxsz, TCA_BPF_NAME, name, len + 1);
+	return nlattr_add(req, TCA_BPF_NAME, name, len + 1);
 }
 
 int bpf_tc_attach(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
@@ -571,12 +558,8 @@ int bpf_tc_attach(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 	__u32 protocol, bpf_flags, handle, priority, parent, prog_id, flags;
 	int ret, ifindex, attach_point, prog_fd;
 	struct bpf_cb_ctx info = {};
+	struct libbpf_nla_req req;
 	struct nlattr *nla;
-	struct {
-		struct nlmsghdr nh;
-		struct tcmsg tc;
-		char buf[256];
-	} req;
 
 	if (!hook || !opts ||
 	    !OPTS_VALID(hook, bpf_tc_hook) ||
@@ -618,25 +601,24 @@ int bpf_tc_attach(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 		return libbpf_err(ret);
 	req.tc.tcm_parent = parent;
 
-	ret = nlattr_add(&req.nh, sizeof(req), TCA_KIND, "bpf", sizeof("bpf"));
+	ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
 	if (ret < 0)
 		return libbpf_err(ret);
-	nla = nlattr_begin_nested(&req.nh, sizeof(req), TCA_OPTIONS);
+	nla = nlattr_begin_nested(&req, TCA_OPTIONS);
 	if (!nla)
 		return libbpf_err(-EMSGSIZE);
-	ret = tc_add_fd_and_name(&req.nh, sizeof(req), prog_fd);
+	ret = tc_add_fd_and_name(&req, prog_fd);
 	if (ret < 0)
 		return libbpf_err(ret);
 	bpf_flags = TCA_BPF_FLAG_ACT_DIRECT;
-	ret = nlattr_add(&req.nh, sizeof(req), TCA_BPF_FLAGS, &bpf_flags,
-			 sizeof(bpf_flags));
+	ret = nlattr_add(&req, TCA_BPF_FLAGS, &bpf_flags, sizeof(bpf_flags));
 	if (ret < 0)
 		return libbpf_err(ret);
-	nlattr_end_nested(&req.nh, nla);
+	nlattr_end_nested(&req, nla);
 
 	info.opts = opts;
 
-	ret = libbpf_netlink_send_recv(&req.nh, get_tc_info, NULL, &info);
+	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
 	if (ret < 0)
 		return libbpf_err(ret);
 	if (!info.processed)
@@ -650,11 +632,7 @@ static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
 {
 	__u32 protocol = 0, handle, priority, parent, prog_id, flags;
 	int ret, ifindex, attach_point, prog_fd;
-	struct {
-		struct nlmsghdr nh;
-		struct tcmsg tc;
-		char buf[256];
-	} req;
+	struct libbpf_nla_req req;
 
 	if (!hook ||
 	    !OPTS_VALID(hook, bpf_tc_hook) ||
@@ -701,13 +679,12 @@ static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
 	req.tc.tcm_parent = parent;
 
 	if (!flush) {
-		ret = nlattr_add(&req.nh, sizeof(req), TCA_KIND,
-				 "bpf", sizeof("bpf"));
+		ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
 		if (ret < 0)
 			return ret;
 	}
 
-	return libbpf_netlink_send_recv(&req.nh, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
 }
 
 int bpf_tc_detach(const struct bpf_tc_hook *hook,
@@ -727,11 +704,7 @@ int bpf_tc_query(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 	__u32 protocol, handle, priority, parent, prog_id, flags;
 	int ret, ifindex, attach_point, prog_fd;
 	struct bpf_cb_ctx info = {};
-	struct {
-		struct nlmsghdr nh;
-		struct tcmsg tc;
-		char buf[256];
-	} req;
+	struct libbpf_nla_req req;
 
 	if (!hook || !opts ||
 	    !OPTS_VALID(hook, bpf_tc_hook) ||
@@ -770,13 +743,13 @@ int bpf_tc_query(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 		return libbpf_err(ret);
 	req.tc.tcm_parent = parent;
 
-	ret = nlattr_add(&req.nh, sizeof(req), TCA_KIND, "bpf", sizeof("bpf"));
+	ret = nlattr_add(&req, TCA_KIND, "bpf", sizeof("bpf"));
 	if (ret < 0)
 		return libbpf_err(ret);
 
 	info.opts = opts;
 
-	ret = libbpf_netlink_send_recv(&req.nh, get_tc_info, NULL, &info);
+	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
 	if (ret < 0)
 		return libbpf_err(ret);
 	if (!info.processed)
diff --git a/tools/lib/bpf/nlattr.c b/tools/lib/bpf/nlattr.c
index b607fa9852b1..f57e77a6e40f 100644
--- a/tools/lib/bpf/nlattr.c
+++ b/tools/lib/bpf/nlattr.c
@@ -27,7 +27,7 @@ static struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 	int totlen = NLA_ALIGN(nla->nla_len);
 
 	*remaining -= totlen;
-	return (struct nlattr *) ((char *) nla + totlen);
+	return (struct nlattr *)((void *)nla + totlen);
 }
 
 static int nla_ok(const struct nlattr *nla, int remaining)
diff --git a/tools/lib/bpf/nlattr.h b/tools/lib/bpf/nlattr.h
index 3c780ab6d022..4d15ae2ff812 100644
--- a/tools/lib/bpf/nlattr.h
+++ b/tools/lib/bpf/nlattr.h
@@ -13,6 +13,7 @@
 #include <string.h>
 #include <errno.h>
 #include <linux/netlink.h>
+#include <linux/rtnetlink.h>
 
 /* avoid multiple definition of netlink features */
 #define __LINUX_NETLINK_H
@@ -52,6 +53,15 @@ struct libbpf_nla_policy {
 	uint16_t	maxlen;
 };
 
+struct libbpf_nla_req {
+	struct nlmsghdr nh;
+	union {
+		struct ifinfomsg ifinfo;
+		struct tcmsg tc;
+	};
+	char buf[128];
+};
+
 /**
  * @ingroup attr
  * Iterate over a stream of attributes
@@ -71,7 +81,7 @@ struct libbpf_nla_policy {
  */
 static inline void *libbpf_nla_data(const struct nlattr *nla)
 {
-	return (char *) nla + NLA_HDRLEN;
+	return (void *)nla + NLA_HDRLEN;
 }
 
 static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
@@ -108,47 +118,47 @@ int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
 
 static inline struct nlattr *nla_data(struct nlattr *nla)
 {
-	return (struct nlattr *)((char *)nla + NLA_HDRLEN);
+	return (struct nlattr *)((void *)nla + NLA_HDRLEN);
 }
 
-static inline struct nlattr *nh_tail(struct nlmsghdr *nh)
+static inline struct nlattr *req_tail(struct libbpf_nla_req *req)
 {
-	return (struct nlattr *)((char *)nh + NLMSG_ALIGN(nh->nlmsg_len));
+	return (struct nlattr *)((void *)req + NLMSG_ALIGN(req->nh.nlmsg_len));
 }
 
-static inline int nlattr_add(struct nlmsghdr *nh, size_t maxsz, int type,
+static inline int nlattr_add(struct libbpf_nla_req *req, int type,
 			     const void *data, int len)
 {
 	struct nlattr *nla;
 
-	if (NLMSG_ALIGN(nh->nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > maxsz)
+	if (NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > sizeof(*req))
 		return -EMSGSIZE;
 	if (!!data != !!len)
 		return -EINVAL;
 
-	nla = nh_tail(nh);
+	nla = req_tail(req);
 	nla->nla_type = type;
 	nla->nla_len = NLA_HDRLEN + len;
 	if (data)
 		memcpy(nla_data(nla), data, len);
-	nh->nlmsg_len = NLMSG_ALIGN(nh->nlmsg_len) + NLA_ALIGN(nla->nla_len);
+	req->nh.nlmsg_len = NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(nla->nla_len);
 	return 0;
 }
 
-static inline struct nlattr *nlattr_begin_nested(struct nlmsghdr *nh,
-						 size_t maxsz, int type)
+static inline struct nlattr *nlattr_begin_nested(struct libbpf_nla_req *req, int type)
 {
 	struct nlattr *tail;
 
-	tail = nh_tail(nh);
-	if (nlattr_add(nh, maxsz, type | NLA_F_NESTED, NULL, 0))
+	tail = req_tail(req);
+	if (nlattr_add(req, type | NLA_F_NESTED, NULL, 0))
 		return NULL;
 	return tail;
 }
 
-static inline void nlattr_end_nested(struct nlmsghdr *nh, struct nlattr *tail)
+static inline void nlattr_end_nested(struct libbpf_nla_req *req,
+				     struct nlattr *tail)
 {
-	tail->nla_len = (char *)nh_tail(nh) - (char *)tail;
+	tail->nla_len = (void *)req_tail(req) - (void *)tail;
 }
 
 #endif /* __LIBBPF_NLATTR_H */