netdev - Re: [bpf-next PATCH v2 2/7] bpf: add sendmsg option for testing BPF programs

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Date:   Thu, 11 Jan 2018 02:28:24 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     John Fastabend <john.fastabend@...il.com>, borkmann@...earbox.net,
        ast@...nel.org
Cc:     netdev@...r.kernel.org
Subject: Re: [bpf-next PATCH v2 2/7] bpf: add sendmsg option for testing BPF
 programs

On 01/10/2018 07:39 PM, John Fastabend wrote:
> When testing BPF programs using sockmap I often want to have more
> control over how sendmsg is exercised. This becomes even more useful
> as new sockmap program types are added.
> 
> This adds a test type option to select type of test to run. Currently,
> only "ping" and "sendmsg" are supported, but more can be added as
> needed.
> 
> The new help argument gives the following,
> 
>  Usage: ./sockmap --cgroup <cgroup_path>
>  options:
>  --help         -h
>  --cgroup       -c
>  --rate         -r
>  --verbose      -v
>  --iov_count    -i
>  --length       -l
>  --test         -t
> 
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> ---
>  samples/sockmap/sockmap_user.c |  143 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 140 insertions(+), 3 deletions(-)
> 
> diff --git a/samples/sockmap/sockmap_user.c b/samples/sockmap/sockmap_user.c
> index 5cbe7a5..2d51672 100644
> --- a/samples/sockmap/sockmap_user.c
> +++ b/samples/sockmap/sockmap_user.c
> @@ -56,6 +56,9 @@
>  	{"cgroup",	required_argument,	NULL, 'c' },
>  	{"rate",	required_argument,	NULL, 'r' },
>  	{"verbose",	no_argument,		NULL, 'v' },
> +	{"iov_count",	required_argument,	NULL, 'i' },
> +	{"length",	required_argument,	NULL, 'l' },
> +	{"test",	required_argument,	NULL, 't' },
>  	{0, 0, NULL, 0 }
>  };
>  
> @@ -184,6 +187,113 @@ static int sockmap_init_sockets(void)
>  	return err;
>  }
>  
> +struct msg_stats {
> +	size_t bytes_sent;
> +	size_t bytes_recvd;
> +};
> +
> +static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
> +		    struct msg_stats *s, bool tx)
> +{
> +	struct msghdr msg = {0};
> +	struct iovec *iov;
> +	int i, flags = 0;
> +
> +	iov = calloc(iov_count, sizeof(struct iovec));
> +	if (!iov)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < iov_count; i++) {
> +		char *d = calloc(iov_length, sizeof(char));
> +
> +		if (!d) {
> +			fprintf(stderr, "iov_count %i/%i OOM\n", i, iov_count);
> +			free(iov);

Here, we free() iov, but not prior allocated iov_base from the loop.

> +			return -ENOMEM;
> +		}
> +		iov[i].iov_base = d;
> +		iov[i].iov_len = iov_length;
> +	}
> +
> +	msg.msg_iov = iov;
> +	msg.msg_iovlen = iov_count;
> +
> +	if (tx) {
> +		for (i = 0; i < cnt; i++) {
> +			int sent = sendmsg(fd, &msg, flags);
> +
> +			if (sent < 0) {
> +				perror("send loop error:");
> +				return sent;

And here as well as other places where we bail out, we don't free anything.

> +			}
> +			s->bytes_sent += sent;
> +		}
> +	} else {
> +		int slct, recv, max_fd = fd;
> +		struct timeval timeout;
> +		float total_bytes;
> +		fd_set w;
> +
> +		total_bytes = (float)iov_count * (float)iov_length * (float)cnt;
> +		while (s->bytes_recvd < total_bytes) {
> +			timeout.tv_sec = 1;
> +			timeout.tv_usec = 0;
> +
> +			/* FD sets */
> +			FD_ZERO(&w);
> +			FD_SET(fd, &w);
> +
> +			slct = select(max_fd + 1, &w, NULL, NULL, &timeout);
> +			if (slct == -1) {
> +				perror("select()");
> +				return slct;
> +			} else if (!slct) {
> +				fprintf(stderr, "unexpected timeout\n");
> +				return slct;
> +			}
> +
> +			recv = recvmsg(fd, &msg, flags);
> +			if (recv < 0) {
> +				if (errno != EWOULDBLOCK) {
> +					perror("recv failed()\n");
> +					return errno;
> +				}
> +			}
> +
> +			s->bytes_recvd += recv;
> +		}
> +	}
> +
> +	for (i = 0; i < iov_count; i++)
> +		free(iov[i].iov_base);
> +	free(iov);
> +	return 0;
> +}