[new] livepatch/selftests: add klp-convert

Add a simple klp-convert livepatch selftest that exercises various
symbol homonym sympos scenarios.

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>

lib/livepatch/Makefile

@@ -5,16 +5,26 @@
 LIVEPATCH_test_klp_atomic_replace.o := y
 LIVEPATCH_test_klp_callbacks_demo.o := y
 LIVEPATCH_test_klp_callbacks_demo2.o := y
+LIVEPATCH_test_klp_convert1.o := y
+LIVEPATCH_test_klp_convert2.o := y
 LIVEPATCH_test_klp_livepatch.o := y
 
 obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
 				test_klp_callbacks_demo.o \
 				test_klp_callbacks_demo2.o \
 				test_klp_callbacks_busy.o \
 				test_klp_callbacks_mod.o \
+				test_klp_convert1.o \
+				test_klp_convert2.o \
+				test_klp_convert_mod.o \
 				test_klp_livepatch.o \
 				test_klp_shadow_vars.o
 
+test_klp_convert_mod-y := \
+	test_klp_convert_mod_a.o \
+	test_klp_convert_mod_b.o
+
 # Target modules to be livepatched require CC_FLAGS_FTRACE
 CFLAGS_test_klp_callbacks_busy.o	+= $(CC_FLAGS_FTRACE)
 CFLAGS_test_klp_callbacks_mod.o		+= $(CC_FLAGS_FTRACE)
+CFLAGS_test_klp_convert_mod.o		+= $(CC_FLAGS_FTRACE)

lib/livepatch/test_klp_convert1.c

@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+/* klp-convert symbols - vmlinux */
+extern char *saved_command_line;
+/* klp-convert symbols - test_klp_convert_mod.ko */
+extern char driver_name[];
+extern char homonym_string[];
+extern const char *get_homonym_string(void);
+extern const char *get_driver_name(void);
+
+void print_saved_command_line(void)
+{
+	pr_info("saved_command_line, 0: %s\n", saved_command_line);
+}
+
+void print_driver_name(void)
+{
+	pr_info("driver_name, 0: %s\n", driver_name);
+	pr_info("get_driver_name(), 0: %s\n", get_driver_name());
+}
+
+void print_homonym_string(void)
+{
+	pr_info("homonym_string, 1: %s\n", homonym_string);
+	pr_info("get_homonym_string(), 1: %s\n", get_homonym_string());
+}
+
+/*
+ * saved_command_line is a unique symbol, so the sympos annotation is
+ * optional.  Provide to test that sympos=0 works correctly.
+ */
+KLP_MODULE_RELOC(vmlinux) vmlinux_relocs[] = {
+	KLP_SYMPOS(saved_command_line, 0)
+};
+
+/*
+ * driver_name symbols can be found in vmlinux (multiple) and also
+ * test_klp_convert_mod, therefore the annotation is required to
+ * clarify that we want the one from test_klp_convert_mod.
+ *
+ * test_klp_convert_mod contains multiple homonym_string and
+ * get_homonym_string symbols, test resolving the first set here and
+ *  the others in test_klp_convert2.c
+ *
+ * get_driver_name is a uniquely named symbol, test that sympos=0
+ * work correctly.
+ */
+KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
+	KLP_SYMPOS(driver_name, 0)
+	KLP_SYMPOS(homonym_string, 1)
+	KLP_SYMPOS(get_homonym_string, 1)
+	KLP_SYMPOS(get_driver_name, 0)
+};
+
+static struct klp_func funcs[] = {
+	{
+	}, { }
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	},
+	{
+		.name = "test_klp_convert_mod",
+		.funcs = funcs,
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int test_klp_convert_init(void)
+{
+	int ret;
+
+	ret = klp_enable_patch(&patch);
+	if (ret)
+		return ret;
+
+	print_saved_command_line();
+	print_driver_name();
+	print_homonym_string();
+
+	return 0;
+}
+
+static void test_klp_convert_exit(void)
+{
+}
+
+module_init(test_klp_convert_init);
+module_exit(test_klp_convert_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert1");

lib/livepatch/test_klp_convert2.c

@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+/* klp-convert symbols - vmlinux */
+extern char *saved_command_line;
+/* klp-convert symbols - test_klp_convert_mod.ko */
+extern char driver_name[];
+extern char homonym_string[];
+extern const char *get_homonym_string(void);
+extern const char *get_driver_name(void);
+
+void print_saved_command_line(void)
+{
+	pr_info("saved_command_line (auto): %s\n", saved_command_line);
+}
+
+void print_driver_name(void)
+{
+	pr_info("driver_name, 0: %s\n", driver_name);
+	pr_info("get_driver_name(), (auto): %s\n", get_driver_name());
+}
+
+void print_homonym_string(void)
+{
+	pr_info("homonym_string, 2: %s\n", homonym_string);
+	pr_info("get_homonym_string(), 2: %s\n", get_homonym_string());
+}
+
+/*
+ * saved_command_line is a uniquely named symbol, so the sympos
+ * annotation is optional.  Skip it and test that klp-convert can
+ * resolve the symbol on its own.
+ */
+
+/*
+ * driver_name symbols can be found in vmlinux (multiple) and also
+ * test_klp_convert_mod, therefore the annotation is required to
+ * clarify that we want the one from test_klp_convert_mod.
+ *
+ * test_klp_convert_mod contains multiple homonym_string symbols,
+ * test_klp_convert1.c resolved to the first one, resolve to the
+ * second one here.
+ *
+ * get_driver_name is a uniquely named symbol, test klp-convert can
+ * resolve it automatically.
+ */
+KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
+	KLP_SYMPOS(driver_name, 0)
+	KLP_SYMPOS(homonym_string, 2)
+	KLP_SYMPOS(get_homonym_string, 2)
+};
+
+static struct klp_func funcs[] = {
+	{
+	}, { }
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	},
+	{
+		.name = "test_klp_convert_mod",
+		.funcs = funcs,
+	}, { }
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int test_klp_convert_init(void)
+{
+	int ret;
+
+	ret = klp_enable_patch(&patch);
+	if (ret)
+		return ret;
+
+	print_saved_command_line();
+	print_driver_name();
+	print_homonym_string();
+
+	return 0;
+}
+
+static void test_klp_convert_exit(void)
+{
+}
+
+module_init(test_klp_convert_init);
+module_exit(test_klp_convert_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert2");

lib/livepatch/test_klp_convert_mod_a.c

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+/* Unique symbols that don't need sympos annotation */
+static const char driver_name[] = KBUILD_MODNAME;
+__used static const char *get_driver_name(void)
+{
+	return driver_name;
+}
+
+/* Common symbol names that need sympos */
+static const char homonym_string[] = "homonym string A";
+__used static const char *get_homonym_string(void)
+{
+	return homonym_string;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert module");

lib/livepatch/test_klp_convert_mod_b.c

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+/*
+ * A second compilation unit to provide another set of similarly named
+ * symbols, forcing a livepatch to use sympos annotations.
+ */
+
+static char homonym_string[] = "homonym string B";
+__used static char *get_homonym_string(void)
+{
+	return homonym_string;
+}

tools/testing/selftests/livepatch/test-livepatch.sh

@@ -6,6 +6,9 @@
 
 MOD_LIVEPATCH=test_klp_livepatch
 MOD_REPLACE=test_klp_atomic_replace
+MOD_KLP_CONVERT_MOD=test_klp_convert_mod
+MOD_KLP_CONVERT1=test_klp_convert1
+MOD_KLP_CONVERT2=test_klp_convert2
 
 set_dynamic_debug
 
@@ -165,4 +168,65 @@ livepatch: '$MOD_REPLACE': unpatching complete
 % rmmod $MOD_REPLACE"
 
 
+# TEST: klp-convert symbols
+# - load a livepatch that modifies the output from /proc/cmdline
+#   including a reference to vmlinux-local symbol that klp-convert
+#   will process
+# - verify correct behavior
+# - unload the livepatch and make sure the patch was removed
+
+echo -n "TEST: klp-convert symbols ... "
+dmesg -C
+
+saved_cmdline=$(cat /proc/cmdline)
+
+load_mod $MOD_KLP_CONVERT_MOD
+
+load_lp $MOD_KLP_CONVERT1
+disable_lp $MOD_KLP_CONVERT1
+unload_lp $MOD_KLP_CONVERT1
+
+load_lp $MOD_KLP_CONVERT2
+disable_lp $MOD_KLP_CONVERT2
+unload_lp $MOD_KLP_CONVERT2
+
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_MOD
+% modprobe $MOD_KLP_CONVERT1
+livepatch: enabling patch '$MOD_KLP_CONVERT1'
+livepatch: '$MOD_KLP_CONVERT1': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT1': starting patching transition
+$MOD_KLP_CONVERT1: saved_command_line, 0: $saved_cmdline
+$MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
+$MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
+livepatch: '$MOD_KLP_CONVERT1': completing patching transition
+livepatch: '$MOD_KLP_CONVERT1': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
+livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': unpatching complete
+% rmmod $MOD_KLP_CONVERT1
+% modprobe $MOD_KLP_CONVERT2
+livepatch: enabling patch '$MOD_KLP_CONVERT2'
+livepatch: '$MOD_KLP_CONVERT2': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT2': starting patching transition
+$MOD_KLP_CONVERT2: saved_command_line (auto): $saved_cmdline
+$MOD_KLP_CONVERT2: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: get_driver_name(), (auto): $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: homonym_string, 2: homonym string B
+$MOD_KLP_CONVERT2: get_homonym_string(), 2: homonym string B
+livepatch: '$MOD_KLP_CONVERT2': completing patching transition
+livepatch: '$MOD_KLP_CONVERT2': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT2/enabled
+livepatch: '$MOD_KLP_CONVERT2': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': unpatching complete
+% rmmod $MOD_KLP_CONVERT2
+% rmmod $MOD_KLP_CONVERT_MOD"
+
 exit 0