1 files changed, 154 insertions, 1 deletions

diff --git a/tools/testing/selftests/net/netlink-dumps.c b/tools/testing/selftests/net/netlink-dumps.c
index 84e29b7dffb6..51129c564d0a 100644
--- a/tools/testing/selftests/net/netlink-dumps.c
+++ b/tools/testing/selftests/net/netlink-dumps.c
@@ -12,10 +12,163 @@
 #include <unistd.h>
 
 #include <linux/genetlink.h>
+#include <linux/neighbour.h>
+#include <linux/netdevice.h>
 #include <linux/netlink.h>
 #include <linux/mqueue.h>
+#include <linux/rtnetlink.h>
 
-#include "../kselftest_harness.h"
+#include "kselftest_harness.h"
+
+#include <ynl.h>
+
+struct ext_ack {
+	int err;
+
+	__u32 attr_offs;
+	__u32 miss_type;
+	__u32 miss_nest;
+	const char *str;
+};
+
+enum get_ea_ret {
+	ERROR = -1,
+	NO_CTRL = 0,
+	FOUND_DONE,
+	FOUND_ERR,
+	FOUND_EXTACK,
+};
+
+static enum get_ea_ret
+nl_get_extack(char *buf, size_t n, struct ext_ack *ea)
+{
+	enum get_ea_ret ret = NO_CTRL;
+	const struct nlmsghdr *nlh;
+	const struct nlattr *attr;
+	ssize_t rem;
+
+	for (rem = n; rem > 0; NLMSG_NEXT(nlh, rem)) {
+		nlh = (struct nlmsghdr *)&buf[n - rem];
+		if (!NLMSG_OK(nlh, rem))
+			return ERROR;
+
+		if (nlh->nlmsg_type == NLMSG_ERROR)
+			ret = FOUND_ERR;
+		else if (nlh->nlmsg_type == NLMSG_DONE)
+			ret = FOUND_DONE;
+		else
+			continue;
+
+		ea->err = -*(int *)NLMSG_DATA(nlh);
+
+		if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+			return ret;
+
+		ynl_attr_for_each(attr, nlh, sizeof(int)) {
+			switch (ynl_attr_type(attr)) {
+			case NLMSGERR_ATTR_OFFS:
+				ea->attr_offs = ynl_attr_get_u32(attr);
+				break;
+			case NLMSGERR_ATTR_MISS_TYPE:
+				ea->miss_type = ynl_attr_get_u32(attr);
+				break;
+			case NLMSGERR_ATTR_MISS_NEST:
+				ea->miss_nest = ynl_attr_get_u32(attr);
+				break;
+			case NLMSGERR_ATTR_MSG:
+				ea->str = ynl_attr_get_str(attr);
+				break;
+			}
+		}
+
+		return FOUND_EXTACK;
+	}
+
+	return ret;
+}
+
+static const struct {
+	struct nlmsghdr nlhdr;
+	struct ndmsg ndm;
+	struct nlattr ahdr;
+	__u32 val;
+} dump_neigh_bad = {
+	.nlhdr = {
+		.nlmsg_len	= sizeof(dump_neigh_bad),
+		.nlmsg_type	= RTM_GETNEIGH,
+		.nlmsg_flags	= NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP,
+		.nlmsg_seq	= 1,
+	},
+	.ndm = {
+		.ndm_family	= 123,
+	},
+	.ahdr = {
+		.nla_len	= 4 + 4,
+		.nla_type	= NDA_FLAGS_EXT,
+	},
+	.val = -1, // should fail MASK validation
+};
+
+TEST(dump_extack)
+{
+	int netlink_sock;
+	int i, cnt, ret;
+	char buf[8192];
+	int one = 1;
+	ssize_t n;
+
+	netlink_sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	ASSERT_GE(netlink_sock, 0);
+
+	n = setsockopt(netlink_sock, SOL_NETLINK, NETLINK_CAP_ACK,
+		       &one, sizeof(one));
+	ASSERT_EQ(n, 0);
+	n = setsockopt(netlink_sock, SOL_NETLINK, NETLINK_EXT_ACK,
+		       &one, sizeof(one));
+	ASSERT_EQ(n, 0);
+	n = setsockopt(netlink_sock, SOL_NETLINK, NETLINK_GET_STRICT_CHK,
+		       &one, sizeof(one));
+	ASSERT_EQ(n, 0);
+
+	/* Dump so many times we fill up the buffer */
+	cnt = 80;
+	for (i = 0; i < cnt; i++) {
+		n = send(netlink_sock, &dump_neigh_bad,
+			 sizeof(dump_neigh_bad), 0);
+		ASSERT_EQ(n, sizeof(dump_neigh_bad));
+	}
+
+	/* Read out the ENOBUFS */
+	n = recv(netlink_sock, buf, sizeof(buf), MSG_DONTWAIT);
+	EXPECT_EQ(n, -1);
+	EXPECT_EQ(errno, ENOBUFS);
+
+	ret = NO_CTRL;
+	for (i = 0; i < cnt; i++) {
+		struct ext_ack ea = {};
+
+		n = recv(netlink_sock, buf, sizeof(buf), MSG_DONTWAIT);
+		if (n < 0) {
+			ASSERT_GE(i, 10);
+			break;
+		}
+		ASSERT_GE(n, (ssize_t)sizeof(struct nlmsghdr));
+
+		ret = nl_get_extack(buf, n, &ea);
+		/* Once we fill the buffer we'll see one ENOBUFS followed
+		 * by a number of EBUSYs. Then the last recv() will finally
+		 * trigger and complete the dump.
+		 */
+		if (ret == FOUND_ERR && (ea.err == ENOBUFS || ea.err == EBUSY))
+			continue;
+		EXPECT_EQ(ret, FOUND_EXTACK);
+		EXPECT_EQ(ea.err, EINVAL);
+		EXPECT_EQ(ea.attr_offs,
+			  sizeof(struct nlmsghdr) + sizeof(struct ndmsg));
+	}
+	/* Make sure last message was a full DONE+extack */
+	EXPECT_EQ(ret, FOUND_EXTACK);
+}
 
 static const struct {
 	struct nlmsghdr nlhdr;