From a9f81b704c4e883a996927e77afdb960a7f47fd9 Mon Sep 17 00:00:00 2001

From: Hangbin Liu <haliu@redhat.com>

Date: Wed, 8 Nov 2017 14:39:09 +0800

Subject: [PATCH] iproute: Add support for extended ack to rtnl_talk

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1380803

Upstream Status: iproute2.git commit b6432e68ac2f

Conflicts: Manually added NETLINK_EXT_ACK define to linux headers.

commit b6432e68ac2f1f6b4ea50aa0d6d47e72c445c71c

Author: Stephen Hemminger <stephen@networkplumber.org>

Date:   Fri Aug 4 09:52:15 2017 -0700

    iproute: Add support for extended ack to rtnl_talk

    Add support for extended ack error reporting via libmnl.

    Add a new function rtnl_talk_extack that takes a callback as an input

    arg. If a netlink response contains extack attributes, the callback is

    is invoked with the the err string, offset in the message and a pointer

    to the message returned by the kernel.

    If iproute2 is built without libmnl, it will still work but

    extended error reports from kernel will not be available.

    Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Signed-off-by: Hangbin Liu <haliu@redhat.com>

squash! iproute: Add support for extended ack to rtnl_talk

---

 include/libnetlink.h    |   6 +++

 include/linux/netlink.h |   1 +

 lib/Makefile            |   7 +++

 lib/libnetlink.c        | 109 +++++++++++++++++++++++++++++++++++++---

 4 files changed, 116 insertions(+), 7 deletions(-)

diff --git a/include/libnetlink.h b/include/libnetlink.h

index bd0267dfcc02a..654aebc0f7632 100644

--- a/include/libnetlink.h

+++ b/include/libnetlink.h

@@ -65,6 +65,9 @@ typedef int (*rtnl_listen_filter_t)(const struct sockaddr_nl *,

 				    struct rtnl_ctrl_data *,

 				    struct nlmsghdr *n, void *);

+typedef int (*nl_ext_ack_fn_t)(const char *errmsg, uint32_t off,

+			       const struct nlmsghdr *inner_nlh);

+

 struct rtnl_dump_filter_arg {

 	rtnl_filter_t filter;

 	void *arg1;

@@ -81,6 +84,9 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,

 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 	      struct nlmsghdr *answer, size_t len)

 	__attribute__((warn_unused_result));

+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,

+	      struct nlmsghdr *answer, size_t len, nl_ext_ack_fn_t errfn)

+	__attribute__((warn_unused_result));

 int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 				   struct nlmsghdr *answer, size_t len)

 	__attribute__((warn_unused_result));

diff --git a/include/linux/netlink.h b/include/linux/netlink.h

index a982b3c004395..d1e26a2bcdcbb 100644

--- a/include/linux/netlink.h

+++ b/include/linux/netlink.h

@@ -113,6 +113,7 @@ struct nlmsgerr {

 #define NETLINK_LISTEN_ALL_NSID		8

 #define NETLINK_LIST_MEMBERSHIPS	9

 #define NETLINK_CAP_ACK			10

+#define NETLINK_EXT_ACK			11

 struct nl_pktinfo {

 	__u32	group;

diff --git a/lib/Makefile b/lib/Makefile

index 1d24ca24b9a39..f81888cca974f 100644

--- a/lib/Makefile

+++ b/lib/Makefile

@@ -4,6 +4,13 @@ ifeq ($(IP_CONFIG_SETNS),y)

 	CFLAGS += -DHAVE_SETNS

 endif

+ifeq ($(HAVE_MNL),y)

+	CFLAGS += $(shell $(PKG_CONFIG) libmnl --cflags)

+	LDLIBS += $(shell $(PKG_CONFIG) libmnl --libs)

+else

+@warn "libmnl required for error support"

+endif

+

 CFLAGS += -fPIC

 UTILOBJ = utils.o rt_names.o ll_types.o ll_proto.o ll_addr.o \

diff --git a/lib/libnetlink.c b/lib/libnetlink.c

index b08518d81f2dd..a0578312e83f8 100644

--- a/lib/libnetlink.c

+++ b/lib/libnetlink.c

@@ -36,6 +36,79 @@

 int rcvbuf = 1024 * 1024;

+#ifdef HAVE_LIBMNL

+#include <libmnl/libmnl.h>

+

+static const enum mnl_attr_data_type extack_policy[NLMSGERR_ATTR_MAX + 1] = {

+	[NLMSGERR_ATTR_MSG]	= MNL_TYPE_NUL_STRING,

+	[NLMSGERR_ATTR_OFFS]	= MNL_TYPE_U32,

+};

+

+static int err_attr_cb(const struct nlattr *attr, void *data)

+{

+	const struct nlattr **tb = data;

+	uint16_t type;

+

+	if (mnl_attr_type_valid(attr, NLMSGERR_ATTR_MAX) < 0)

+		return MNL_CB_ERROR;

+

+	type = mnl_attr_get_type(attr);

+	if (mnl_attr_validate(attr, extack_policy[type]) < 0)

+		return MNL_CB_ERROR;

+

+

+	tb[type] = attr;

+	return MNL_CB_OK;

+}

+

+

+/* dump netlink extended ack error message */

+static int nl_dump_ext_err(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)

+{

+	struct nlattr *tb[NLMSGERR_ATTR_MAX + 1];

+	const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);

+	const struct nlmsghdr *err_nlh = NULL;

+	unsigned int hlen = sizeof(*err);

+	const char *errmsg = NULL;

+	uint32_t off = 0;

+

+	if (!errfn)

+		return 0;

+

+	/* no TLVs, nothing to do here */

+	if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))

+		return 0;

+

+	/* if NLM_F_CAPPED is set then the inner err msg was capped */

+	if (!(nlh->nlmsg_flags & NLM_F_CAPPED))

+		hlen += mnl_nlmsg_get_payload_len(&err->msg);

+

+	mnl_attr_parse(nlh, hlen, err_attr_cb, tb);

+

+	if (tb[NLMSGERR_ATTR_MSG])

+		errmsg = mnl_attr_get_str(tb[NLMSGERR_ATTR_MSG]);

+

+	if (tb[NLMSGERR_ATTR_OFFS]) {

+		off = mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]);

+

+		if (off > nlh->nlmsg_len) {

+			fprintf(stderr,

+				"Invalid offset for NLMSGERR_ATTR_OFFS\n");

+			off = 0;

+		} else if (!(nlh->nlmsg_flags & NLM_F_CAPPED))

+			err_nlh = &err->msg;

+	}

+

+	return errfn(errmsg, off, err_nlh);

+}

+#else

+/* No extended error ack without libmnl */

+static int nl_dump_ext_err(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)

+{

+	return 0;

+}

+#endif

+

 void rtnl_close(struct rtnl_handle *rth)

 {

 	if (rth->fd >= 0) {

@@ -49,6 +122,7 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,

 {

 	socklen_t addr_len;

 	int sndbuf = 32768;

+	int one = 1;

 	memset(rth, 0, sizeof(*rth));

@@ -71,6 +145,10 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,

 		return -1;

 	}

+	/* Older kernels may no support extended ACK reporting */

+	setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,

+		   &one, sizeof(one));

+

 	memset(&rth->local, 0, sizeof(rth->local));

 	rth->local.nl_family = AF_NETLINK;

 	rth->local.nl_groups = subscriptions;

@@ -421,9 +499,19 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,

 	return rtnl_dump_filter_l(rth, a);

 }

+static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,

+			    nl_ext_ack_fn_t errfn)

+{

+	if (nl_dump_ext_err(h, errfn))

+		return;

+

+	fprintf(stderr, "RTNETLINK answers: %s\n",

+		strerror(-err->error));

+}

+

 static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 		       struct nlmsghdr *answer, size_t maxlen,

-		       bool show_rtnl_err)

+		       bool show_rtnl_err, nl_ext_ack_fn_t errfn)

 {

 	int status;

 	unsigned int seq;

@@ -510,10 +598,10 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 					return 0;

 				}

-				if (rtnl->proto != NETLINK_SOCK_DIAG && show_rtnl_err)

-					fprintf(stderr,

-						"RTNETLINK answers: %s\n",

-						strerror(-err->error));

+				if (rtnl->proto != NETLINK_SOCK_DIAG &&

+				    show_rtnl_err)

+					rtnl_talk_error(h, err, errfn);

+

 				errno = -err->error;

 				return -1;

 			}

@@ -545,13 +633,20 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 	      struct nlmsghdr *answer, size_t maxlen)

 {

-	return __rtnl_talk(rtnl, n, answer, maxlen, true);

+	return __rtnl_talk(rtnl, n, answer, maxlen, true, NULL);

+}

+

+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,

+		     struct nlmsghdr *answer, size_t maxlen,

+		     nl_ext_ack_fn_t errfn)

+{

+	return __rtnl_talk(rtnl, n, answer, maxlen, true, errfn);

 }

 int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 				   struct nlmsghdr *answer, size_t maxlen)

 {

-	return __rtnl_talk(rtnl, n, answer, maxlen, false);

+	return __rtnl_talk(rtnl, n, answer, maxlen, false, NULL);

 }

 int rtnl_listen_all_nsid(struct rtnl_handle *rth)

-- 

2.21.0