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authorKees Cook <kees+treewide@kernel.org>2026-09-02 15:31:14 -0700
committerKees Cook <kees@kernel.org>2026-09-04 21:37:00 -0700
commit3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch)
treec65086f9bdcd48c6360fb7cb4598bca084da1f32 /samples/livepatch/livepatch-callbacks-demo.c
downloadlinux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz
linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'samples/livepatch/livepatch-callbacks-demo.c')
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diff --git a/samples/livepatch/livepatch-callbacks-demo.c b/samples/livepatch/livepatch-callbacks-demo.c
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+++ b/samples/livepatch/livepatch-callbacks-demo.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
+ */
+
+/*
+ * livepatch-callbacks-demo.c - (un)patching callbacks livepatch demo
+ *
+ *
+ * Purpose
+ * -------
+ *
+ * Demonstration of registering livepatch (un)patching callbacks.
+ *
+ *
+ * Usage
+ * -----
+ *
+ * Step 1 - load the simple module
+ *
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ *
+ *
+ * Step 2 - load the demonstration livepatch (with callbacks)
+ *
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ *
+ * Step 3 - cleanup
+ *
+ * echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
+ * rmmod livepatch_callbacks_demo
+ * rmmod livepatch_callbacks_mod
+ *
+ * Watch dmesg output to see livepatch enablement, callback execution
+ * and patching operations for both vmlinux and module targets.
+ *
+ * NOTE: swap the insmod order of livepatch-callbacks-mod.ko and
+ * livepatch-callbacks-demo.ko to observe what happens when a
+ * target module is loaded after a livepatch with callbacks.
+ *
+ * NOTE: 'pre_patch_ret' is a module parameter that sets the pre-patch
+ * callback return status. Try setting up a non-zero status
+ * such as -19 (-ENODEV):
+ *
+ * # Load demo livepatch, vmlinux is patched
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ * # Setup next pre-patch callback to return -ENODEV
+ * echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
+ *
+ * # Module loader refuses to load the target module
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ * insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko: No such device
+ *
+ * NOTE: There is a second target module,
+ * livepatch-callbacks-busymod.ko, available for experimenting
+ * with livepatch (un)patch callbacks. This module contains
+ * a 'sleep_secs' parameter that parks the module on one of the
+ * functions that the livepatch demo module wants to patch.
+ * Modifying this value and tweaking the order of module loads can
+ * effectively demonstrate stalled patch transitions:
+ *
+ * # Load a target module, let it park on 'busymod_work_func' for
+ * # thirty seconds
+ * insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
+ *
+ * # Meanwhile load the livepatch
+ * insmod samples/livepatch/livepatch-callbacks-demo.ko
+ *
+ * # ... then load and unload another target module while the
+ * # transition is in progress
+ * insmod samples/livepatch/livepatch-callbacks-mod.ko
+ * rmmod samples/livepatch/livepatch-callbacks-mod.ko
+ *
+ * # Finally cleanup
+ * echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
+ * rmmod samples/livepatch/livepatch-callbacks-demo.ko
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+static int pre_patch_ret;
+module_param(pre_patch_ret, int, 0644);
+MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret (default=0)");
+
+static const char *const module_state[] = {
+ [MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",
+ [MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",
+ [MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",
+ [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
+};
+
+static void callback_info(const char *callback, struct klp_object *obj)
+{
+ if (obj->mod)
+ pr_info("%s: %s -> %s\n", callback, obj->mod->name,
+ module_state[obj->mod->state]);
+ else
+ pr_info("%s: vmlinux\n", callback);
+}
+
+/* Executed on object patching (ie, patch enablement) */
+static int pre_patch_callback(struct klp_object *obj)
+{
+ callback_info(__func__, obj);
+ return pre_patch_ret;
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_patch_callback(struct klp_object *obj)
+{
+ callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void pre_unpatch_callback(struct klp_object *obj)
+{
+ callback_info(__func__, obj);
+}
+
+/* Executed on object unpatching (ie, patch disablement) */
+static void post_unpatch_callback(struct klp_object *obj)
+{
+ callback_info(__func__, obj);
+}
+
+static void patched_work_func(struct work_struct *work)
+{
+ pr_info("%s\n", __func__);
+}
+
+static struct klp_func no_funcs[] = {
+ { }
+};
+
+static struct klp_func busymod_funcs[] = {
+ {
+ .old_name = "busymod_work_func",
+ .new_func = patched_work_func,
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ .name = NULL, /* vmlinux */
+ .funcs = no_funcs,
+ .callbacks = {
+ .pre_patch = pre_patch_callback,
+ .post_patch = post_patch_callback,
+ .pre_unpatch = pre_unpatch_callback,
+ .post_unpatch = post_unpatch_callback,
+ },
+ }, {
+ .name = "livepatch_callbacks_mod",
+ .funcs = no_funcs,
+ .callbacks = {
+ .pre_patch = pre_patch_callback,
+ .post_patch = post_patch_callback,
+ .pre_unpatch = pre_unpatch_callback,
+ .post_unpatch = post_unpatch_callback,
+ },
+ }, {
+ .name = "livepatch_callbacks_busymod",
+ .funcs = busymod_funcs,
+ .callbacks = {
+ .pre_patch = pre_patch_callback,
+ .post_patch = post_patch_callback,
+ .pre_unpatch = pre_unpatch_callback,
+ .post_unpatch = post_unpatch_callback,
+ },
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int livepatch_callbacks_demo_init(void)
+{
+ return klp_enable_patch(&patch);
+}
+
+static void livepatch_callbacks_demo_exit(void)
+{
+}
+
+module_init(livepatch_callbacks_demo_init);
+module_exit(livepatch_callbacks_demo_exit);
+MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks");
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");