From 49e7c0e7c8c9a982fd3aa69bbed4e306a1dcb331 Mon Sep 17 00:00:00 2001

From: Hangbin Liu <haliu@redhat.com>

Date: Wed, 8 Nov 2017 14:39:12 +0800

Subject: [PATCH] lib/libnetlink: re malloc buff if size is not enough

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

Upstream Status: iproute2.git net-next commit 2d34851cd341

commit 2d34851cd341f0e1b3fc17ca3e6e874229f3a1f8

Author: Hangbin Liu <liuhangbin@gmail.com>

Date:   Thu Oct 26 09:41:46 2017 +0800

    lib/libnetlink: re malloc buff if size is not enough

    With commit 72b365e8e0fd ("libnetlink: Double the dump buffer size")

    we doubled the buffer size to support more VFs. But the VFs number is

    increasing all the time. Some customers even use more than 200 VFs now.

    We could not double it everytime when the buffer is not enough. Let's just

    not hard code the buffer size and malloc the correct number when running.

    Introduce function rtnl_recvmsg() to always return a newly allocated buffer.

    The caller need to free it after using.

    Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>

    Signed-off-by: Phil Sutter <phil@nwl.cc>

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

---

 lib/libnetlink.c | 114 +++++++++++++++++++++++++++++++++--------------

 1 file changed, 80 insertions(+), 34 deletions(-)

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

index a0578312e83f8..446c9605ba19b 100644

--- a/lib/libnetlink.c

+++ b/lib/libnetlink.c

@@ -386,6 +386,64 @@ static void rtnl_dump_error(const struct rtnl_handle *rth,

 	}

 }

+static int __rtnl_recvmsg(int fd, struct msghdr *msg, int flags)

+{

+	int len;

+

+	do {

+		len = recvmsg(fd, msg, flags);

+	} while (len < 0 && (errno == EINTR || errno == EAGAIN));

+

+	if (len < 0) {

+		fprintf(stderr, "netlink receive error %s (%d)\n",

+			strerror(errno), errno);

+		return -errno;

+	}

+

+	if (len == 0) {

+		fprintf(stderr, "EOF on netlink\n");

+		return -ENODATA;

+	}

+

+	return len;

+}

+

+static int rtnl_recvmsg(int fd, struct msghdr *msg, char **answer)

+{

+	struct iovec *iov = msg->msg_iov;

+	char *buf;

+	int len;

+

+	iov->iov_base = NULL;

+	iov->iov_len = 0;

+

+	len = __rtnl_recvmsg(fd, msg, MSG_PEEK | MSG_TRUNC);

+	if (len < 0)

+		return len;

+

+	buf = malloc(len);

+	if (!buf) {

+		fprintf(stderr, "malloc error: not enough buffer\n");

+		return -ENOMEM;

+	}

+

+	iov->iov_base = buf;

+	iov->iov_len = len;

+

+	len = __rtnl_recvmsg(fd, msg, 0);

+	if (len < 0) {

+		free(buf);

+		return len;

+	}

+

+	if (answer)

+		*answer = buf;

+	else

+		free(buf);

+

+	return len;

+}

+

 int rtnl_dump_filter_l(struct rtnl_handle *rth,

 		       const struct rtnl_dump_filter_arg *arg)

 {

@@ -397,31 +455,18 @@ int rtnl_dump_filter_l(struct rtnl_handle *rth,

 		.msg_iov = &iov,

 		.msg_iovlen = 1,

 	};

-	char buf[32768];

+	char *buf;

 	int dump_intr = 0;

-	iov.iov_base = buf;

 	while (1) {

 		int status;

 		const struct rtnl_dump_filter_arg *a;

 		int found_done = 0;

 		int msglen = 0;

-		iov.iov_len = sizeof(buf);

-		status = recvmsg(rth->fd, &msg, 0);

-

-		if (status < 0) {

-			if (errno == EINTR || errno == EAGAIN)

-				continue;

-			fprintf(stderr, "netlink receive error %s (%d)\n",

-				strerror(errno), errno);

-			return -1;

-		}

-

-		if (status == 0) {

-			fprintf(stderr, "EOF on netlink\n");

-			return -1;

-		}

+		status = rtnl_recvmsg(rth->fd, &msg, &buf;;

+		if (status < 0)

+			return status;

 		if (rth->dump_fp)

 			fwrite(buf, 1, NLMSG_ALIGN(status), rth->dump_fp);

@@ -446,8 +491,10 @@ int rtnl_dump_filter_l(struct rtnl_handle *rth,

 				if (h->nlmsg_type == NLMSG_DONE) {

 					err = rtnl_dump_done(h);

-					if (err < 0)

+					if (err < 0) {

+						free(buf);

 						return -1;

+					}

 					found_done = 1;

 					break; /* process next filter */

@@ -455,19 +502,23 @@ int rtnl_dump_filter_l(struct rtnl_handle *rth,

 				if (h->nlmsg_type == NLMSG_ERROR) {

 					rtnl_dump_error(rth, h);

+					free(buf);

 					return -1;

 				}

 				if (!rth->dump_fp) {

 					err = a->filter(&nladdr, h, a->arg1);

-					if (err < 0)

+					if (err < 0) {

+						free(buf);

 						return err;

+					}

 				}

 skip_it:

 				h = NLMSG_NEXT(h, msglen);

 			}

 		}

+		free(buf);

 		if (found_done) {

 			if (dump_intr)

@@ -527,7 +578,7 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 		.msg_iov = &iov,

 		.msg_iovlen = 1,

 	};

-	char   buf[32768] = {};

+	char *buf;

 	n->nlmsg_seq = seq = ++rtnl->seq;

@@ -540,22 +591,12 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 		return -1;

 	}

-	iov.iov_base = buf;

 	while (1) {

-		iov.iov_len = sizeof(buf);

-		status = recvmsg(rtnl->fd, &msg, 0);

+		status = rtnl_recvmsg(rtnl->fd, &msg, &buf;;

+

+		if (status < 0)

+			return status;

-		if (status < 0) {

-			if (errno == EINTR || errno == EAGAIN)

-				continue;

-			fprintf(stderr, "netlink receive error %s (%d)\n",

-				strerror(errno), errno);

-			return -1;

-		}

-		if (status == 0) {

-			fprintf(stderr, "EOF on netlink\n");

-			return -1;

-		}

 		if (msg.msg_namelen != sizeof(nladdr)) {

 			fprintf(stderr,

 				"sender address length == %d\n",

@@ -569,6 +610,7 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 			if (l < 0 || len > status) {

 				if (msg.msg_flags & MSG_TRUNC) {

 					fprintf(stderr, "Truncated message\n");

+					free(buf);

 					return -1;

 				}

 				fprintf(stderr,

@@ -595,6 +637,7 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 					if (answer)

 						memcpy(answer, h,

 						       MIN(maxlen, h->nlmsg_len));

+					free(buf);

 					return 0;

 				}

@@ -603,12 +646,14 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 					rtnl_talk_error(h, err, errfn);

 				errno = -err->error;

+				free(buf);

 				return -1;

 			}

 			if (answer) {

 				memcpy(answer, h,

 				       MIN(maxlen, h->nlmsg_len));

+				free(buf);

 				return 0;

 			}

@@ -617,6 +662,7 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,

 			status -= NLMSG_ALIGN(len);

 			h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));

 		}

+		free(buf);

 		if (msg.msg_flags & MSG_TRUNC) {

 			fprintf(stderr, "Message truncated\n");

-- 

2.21.0