add VTY option gtp/mockup, for VTY tests

To avoid actions that require cap_net_admin permissions on build
servers, add this option to "dry run" all kernel GTP actions. Same will
be added for netfilter rules.

On startup, osmo-upf opens sockets to GTP kernel module / NFT ctx.
However, on build servers, this would require giving cap_net_admin
permissions just to run the VTY tests.

Related: SYS#5599
Change-Id: I3b9c796186307fd8562abcff3f0ccfab0e88b6c8

doc/examples/osmo-upf/osmo-upf-mockup.cfg

@@ -0,0 +1,17 @@
+log stderr
+ logging filter all 1
+ logging color 1
+ logging print level 1
+ logging print category 1
+ logging print category-hex 0
+ logging print file basename last
+ logging print extended-timestamp 1
+ logging level set-all debug
+ logging level set-all notice
+ logging level set-all info
+
+timer pfcp x24 5000
+pfcp
+ local-addr 127.0.0.1
+gtp
+ mockup

include/osmocom/upf/upf.h

@@ -73,6 +73,9 @@ struct g_upf {
 		struct up_endpoint *ep;
 	} pfcp;
 	struct {
+		/* if true, don't actually send commands to the GTP kernel module, just return success. */
+		bool mockup;
+
 		/* GTP devices as in osmo-upf.cfg */
 		struct gtp_vty_cfg vty_cfg;
 

osmoappdesc.py

@@ -15,13 +15,13 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>
 
 app_configs = {
-    "osmo-upf": ["doc/examples/osmo-upf/osmo-upf.cfg"]
+    "osmo-upf": ["doc/examples/osmo-upf/osmo-upf-mockup.cfg"]
 }
 
 apps = [(4275, "src/osmo-upf/osmo-upf", "OsmoUPF", "osmo-upf")
         ]
 
 vty_command = ["./src/osmo-upf/osmo-upf", "-c",
-               "doc/examples/osmo-upf/osmo-upf.cfg"]
+               "doc/examples/osmo-upf/osmo-upf-mockup.cfg"]
 
 vty_app = apps[0]

src/osmo-upf/up_gtp_action.c

@@ -83,6 +83,12 @@ static int up_gtp_action_enable_disable(struct up_gtp_action *a, bool enable)
 
 	switch (a->kind) {
 	case UP_GTP_U_ENDECAPS:
+		if (g_upf->gtp.mockup) {
+			LOG_UP_GTP_ACTION(a, LOGL_NOTICE, "gtp/mockup active, skipping GTP action %s\n",
+					  enable ? "enable" : "disable");
+			return 0;
+		}
+
 		/* use the first available GTP device.
 		 * TODO: select by interface name?
 		 */

src/osmo-upf/upf_gtp.c

@@ -167,7 +167,14 @@ int upf_gtp_dev_open(const char *name, bool create_gtp_dev, const char *local_ad
 		},
 	};
 	int rc;
-	struct upf_gtp_dev *dev = upf_gtp_dev_alloc(name, local_addr);
+	struct upf_gtp_dev *dev;
+
+	if (g_upf->gtp.mockup) {
+		LOGP(DGTP, LOGL_NOTICE, "gtp/mockup active: not opening GTP device '%s'\n", name);
+		return 0;
+	}
+
+	dev = upf_gtp_dev_alloc(name, local_addr);
 	if (!dev)
 		return -EIO;
 
@@ -245,6 +252,11 @@ void upf_gtp_genl_close()
 /* Open an MNL socket which allows to create and remove GTP devices (requires CAP_NET_ADMIN). */
 int upf_gtp_genl_open()
 {
+	if (g_upf->gtp.mockup) {
+		LOGP(DGTP, LOGL_NOTICE, "gtp/mockup active: not opening mnl_socket\n");
+		return 0;
+	}
+
 	if (g_upf->gtp.nl && g_upf->gtp.genl_id >= 0)
 		return 0;
 

src/osmo-upf/upf_vty.c

@@ -96,6 +96,9 @@ static int config_write_gtp(struct vty *vty)
 	struct gtp_vty_cfg_dev *d;
 	vty_out(vty, "gtp%s", VTY_NEWLINE);
 
+	if (g_upf->gtp.mockup)
+		vty_out(vty, " mockup%s", VTY_NEWLINE);
+
 	llist_for_each_entry(d, &gtp_vty.devs, entry) {
 		if (d->create) {
 			vty_out(vty, " dev create %s", d->dev_name);
@@ -111,6 +114,23 @@ static int config_write_gtp(struct vty *vty)
 
 #define DEV_STR "Configure the GTP device to use for encaps/decaps.\n"
 
+DEFUN(cfg_gtp_mockup, cfg_gtp_mockup_cmd,
+      "mockup",
+      "don't actually send commands to the GTP kernel module, just return success\n")
+{
+	g_upf->gtp.mockup = true;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gtp_no_mockup, cfg_gtp_no_mockup_cmd,
+      "no mockup",
+      NO_STR
+      "operate GTP kernel module normally\n")
+{
+	g_upf->gtp.mockup = false;
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_gtp_dev_create, cfg_gtp_dev_create_cmd,
       "dev create DEVNAME [LISTEN_ADDR]",
       DEV_STR
@@ -279,6 +299,8 @@ void upf_vty_init()
 	install_node(&cfg_gtp_node, config_write_gtp);
 	install_element(CONFIG_NODE, &cfg_gtp_cmd);
 
+	install_element(GTP_NODE, &cfg_gtp_mockup_cmd);
+	install_element(GTP_NODE, &cfg_gtp_no_mockup_cmd);
 	install_element(GTP_NODE, &cfg_gtp_dev_create_cmd);
 	install_element(GTP_NODE, &cfg_gtp_dev_use_cmd);
 	install_element(GTP_NODE, &cfg_gtp_dev_del_cmd);

tests/Makefile.am

@@ -48,7 +48,7 @@ VTY_TEST ?= *.vty
 vty-test:
 	osmo_verify_transcript_vty.py -v \
 		-n OsmoUPF -p 4275 \
-		-r "$(top_builddir)/src/osmo-upf/osmo-upf -c $(top_srcdir)/doc/examples/osmo-upf/osmo-upf.cfg" \
+		-r "$(top_builddir)/src/osmo-upf/osmo-upf -c $(top_srcdir)/doc/examples/osmo-upf/osmo-upf-mockup.cfg" \
 		$(U) $(srcdir)/$(VTY_TEST)
 
 check-local: atconfig $(TESTSUITE)