bpf: sockmap, add sample option to test apply_bytes helper

This adds an option to test the apply_bytes helper. This option lets
the user specify an int on the command line specifying how much data
each verdict should apply to.

When this is set a map entry is set with the bytes input by the user
and then the specified program --txmsg or --txmsg_redir will use the
value and set the applied data. If no other option is set then a
default --txmsg_apply program is run. This program will drop pkts
if an error is detected on the bytes map lookup. Useful to verify
the map lookup and apply helper are working and causing a hard
error if it is not.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 18 insertions, 1 deletions

diff --git a/samples/sockmap/sockmap_user.c b/samples/sockmap/sockmap_user.c
index 8017ad7afea9..41774ec0f0b3 100644
--- a/samples/sockmap/sockmap_user.c
+++ b/samples/sockmap/sockmap_user.c
@@ -59,6 +59,7 @@ int txmsg_pass;
 int txmsg_noisy;
 int txmsg_redir;
 int txmsg_redir_noisy;
+int txmsg_apply;
 
 static const struct option long_options[] = {
 	{"help",	no_argument,		NULL, 'h' },
@@ -73,6 +74,7 @@ static const struct option long_options[] = {
 	{"txmsg_noisy",		no_argument,	&txmsg_noisy, 1  },
 	{"txmsg_redir",		no_argument,	&txmsg_redir, 1  },
 	{"txmsg_redir_noisy",	no_argument,	&txmsg_redir_noisy, 1},
+	{"txmsg_apply",	required_argument,	NULL, 'a'},
 	{0, 0, NULL, 0 }
 };
 
@@ -546,7 +548,9 @@ int main(int argc, char **argv)
 	while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
-		/* Cgroup configuration */
+		case 'a':
+			txmsg_apply = atoi(optarg);
+			break;
 		case 'c':
 			cg_fd = open(optarg, O_DIRECTORY, O_RDONLY);
 			if (cg_fd < 0) {
@@ -665,6 +669,8 @@ run:
 		tx_prog_fd = prog_fd[5];
 	else if (txmsg_redir_noisy)
 		tx_prog_fd = prog_fd[6];
+	else if (txmsg_apply)
+		tx_prog_fd = prog_fd[7];
 	else
 		tx_prog_fd = 0;
 
@@ -699,6 +705,17 @@ run:
 				err, strerror(errno));
 			return err;
 		}
+
+		if (txmsg_apply) {
+			err = bpf_map_update_elem(map_fd[3],
+						  &i, &txmsg_apply, BPF_ANY);
+			if (err) {
+				fprintf(stderr,
+					"ERROR: bpf_map_update_elem (apply_bytes):  %d (%s\n",
+					err, strerror(errno));
+				return err;
+			}
+		}
 	}
 	if (test == PING_PONG)
 		err = forever_ping_pong(rate, &options);