Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

Pull livepatching fixes from Jiri Kosina:

 - symbol lookup locking fix, from Miroslav Benes

 - error handling improvements in case of failure of the module coming
   notifier, from Minfei Huang

 - we were too pessimistic when kASLR has been enabled on x86 and were
   dropping address hints on the floor unnecessarily in such case.  Fix
   from Jiri Kosina

 - a few other small fixes and cleanups

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: add module locking around kallsyms calls
  livepatch: annotate klp_init() with __init
  livepatch: introduce patch/func-walking helpers
  livepatch: make kobject in klp_object statically allocated
  livepatch: Prevent patch inconsistencies if the coming module notifier fails
  livepatch: match return value to function signature
  x86: kaslr: fix build due to missing ALIGN definition
  livepatch: x86: make kASLR logic more accurate
  x86: introduce kaslr_offset()

6 files changed, 79 insertions, 38 deletions

diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h
index 2d29197bd2fb..19c099afa861 100644
--- a/arch/x86/include/asm/livepatch.h
+++ b/arch/x86/include/asm/livepatch.h
@@ -21,6 +21,7 @@
 #ifndef _ASM_X86_LIVEPATCH_H
 #define _ASM_X86_LIVEPATCH_H
 
+#include <asm/setup.h>
 #include <linux/module.h>
 #include <linux/ftrace.h>
 
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f69e06b283fb..11af24e09c8a 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -60,17 +60,24 @@ static inline void x86_ce4100_early_setup(void) { }
 #ifndef _SETUP
 
 #include <asm/espfix.h>
+#include <linux/kernel.h>
 
 /*
  * This is set up by the setup-routine at boot-time
  */
 extern struct boot_params boot_params;
+extern char _text[];
 
 static inline bool kaslr_enabled(void)
 {
         return !!(boot_params.hdr.loadflags & KASLR_FLAG);
 }
 
+static inline unsigned long kaslr_offset(void)
+{
+        return (unsigned long)&_text - __START_KERNEL;
+}
+
 /*
  * Do NOT EVER look at the BIOS memory size location.
  * It does not work on many machines.
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 11546b462fa6..819ab3f9c9c7 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -26,6 +26,7 @@
 #include <asm/io_apic.h>
 #include <asm/debugreg.h>
 #include <asm/kexec-bzimage64.h>
+#include <asm/setup.h>
 
 #ifdef CONFIG_KEXEC_FILE
 static struct kexec_file_ops *kexec_file_loaders[] = {
@@ -335,7 +336,7 @@ void arch_crash_save_vmcoreinfo(void)
         VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 #endif
         vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
-                              (unsigned long)&_text - __START_KERNEL);
+                              kaslr_offset());
 }
 
 /* arch-dependent functionality related to kexec file-based syscall */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 265a6fdea8b7..39ca113676fe 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -836,7 +836,7 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 {
         if (kaslr_enabled()) {
                 pr_emerg("Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx)\n",
-                         (unsigned long)&_text - __START_KERNEL,
+                         kaslr_offset(),
                          __START_KERNEL,
                          __START_KERNEL_map,
                          MODULES_VADDR-1);
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index ee6dbb39a809..31db7a05dd36 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -99,7 +99,7 @@ struct klp_object {
         struct klp_func *funcs;
 
         /* internal */
-        struct kobject *kobj;
+        struct kobject kobj;
         struct module *mod;
         enum klp_state state;
 };
@@ -123,6 +123,12 @@ struct klp_patch {
         enum klp_state state;
 };
 
+#define klp_for_each_object(patch, obj) \
+        for (obj = patch->objs; obj->funcs; obj++)
+
+#define klp_for_each_func(obj, func) \
+        for (func = obj->funcs; func->old_name; func++)
+
 int klp_register_patch(struct klp_patch *);
 int klp_unregister_patch(struct klp_patch *);
 int klp_enable_patch(struct klp_patch *);
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 284e2691e380..c40ebcca0495 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -128,7 +128,7 @@ static bool klp_is_patch_registered(struct klp_patch *patch)
 
 static bool klp_initialized(void)
 {
-        return klp_root_kobj;
+        return !!klp_root_kobj;
 }
 
 struct klp_find_arg {
@@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name,
                 .count = 0
         };
 
+        mutex_lock(&module_mutex);
         kallsyms_on_each_symbol(klp_find_callback, &args);
+        mutex_unlock(&module_mutex);
 
         if (args.count == 0)
                 pr_err("symbol '%s' not found in symbol table\n", name);
@@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
                 .name = name,
                 .addr = addr,
         };
+        int ret;
 
-        if (kallsyms_on_each_symbol(klp_verify_callback, &args))
-                return 0;
+        mutex_lock(&module_mutex);
+        ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
+        mutex_unlock(&module_mutex);
 
-        pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
-                name, addr);
-        return -EINVAL;
+        if (!ret) {
+                pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
+                        name, addr);
+                return -EINVAL;
+        }
+
+        return 0;
 }
 
 static int klp_find_verify_func_addr(struct klp_object *obj,
@@ -234,8 +242,9 @@ static int klp_find_verify_func_addr(struct klp_object *obj,
         int ret;
 
 #if defined(CONFIG_RANDOMIZE_BASE)
-        /* KASLR is enabled, disregard old_addr from user */
-        func->old_addr = 0;
+        /* If KASLR has been enabled, adjust old_addr accordingly */
+        if (kaslr_enabled() && func->old_addr)
+                func->old_addr += kaslr_offset();
 #endif
 
         if (!func->old_addr || klp_is_module(obj))
@@ -422,7 +431,7 @@ static void klp_disable_object(struct klp_object *obj)
 {
         struct klp_func *func;
 
-        for (func = obj->funcs; func->old_name; func++)
+        klp_for_each_func(obj, func)
                 if (func->state == KLP_ENABLED)
                         klp_disable_func(func);
 
@@ -440,7 +449,7 @@ static int klp_enable_object(struct klp_object *obj)
         if (WARN_ON(!klp_is_object_loaded(obj)))
                 return -EINVAL;
 
-        for (func = obj->funcs; func->old_name; func++) {
+        klp_for_each_func(obj, func) {
                 ret = klp_enable_func(func);
                 if (ret) {
                         klp_disable_object(obj);
@@ -463,7 +472,7 @@ static int __klp_disable_patch(struct klp_patch *patch)
 
         pr_notice("disabling patch '%s'\n", patch->mod->name);
 
-        for (obj = patch->objs; obj->funcs; obj++) {
+        klp_for_each_object(patch, obj) {
                 if (obj->state == KLP_ENABLED)
                         klp_disable_object(obj);
         }
@@ -523,7 +532,7 @@ static int __klp_enable_patch(struct klp_patch *patch)
 
         pr_notice("enabling patch '%s'\n", patch->mod->name);
 
-        for (obj = patch->objs; obj->funcs; obj++) {
+        klp_for_each_object(patch, obj) {
                 if (!klp_is_object_loaded(obj))
                         continue;
 
@@ -651,6 +660,15 @@ static struct kobj_type klp_ktype_patch = {
         .default_attrs = klp_patch_attrs,
 };
 
+static void klp_kobj_release_object(struct kobject *kobj)
+{
+}
+
+static struct kobj_type klp_ktype_object = {
+        .release = klp_kobj_release_object,
+        .sysfs_ops = &kobj_sysfs_ops,
+};
+
 static void klp_kobj_release_func(struct kobject *kobj)
 {
 }
@@ -680,7 +698,7 @@ static void klp_free_object_loaded(struct klp_object *obj)
 
         obj->mod = NULL;
 
-        for (func = obj->funcs; func->old_name; func++)
+        klp_for_each_func(obj, func)
                 func->old_addr = 0;
 }
 
@@ -695,7 +713,7 @@ static void klp_free_objects_limited(struct klp_patch *patch,
 
         for (obj = patch->objs; obj->funcs && obj != limit; obj++) {
                 klp_free_funcs_limited(obj, NULL);
-                kobject_put(obj->kobj);
+                kobject_put(&obj->kobj);
         }
 }
 
@@ -713,7 +731,7 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
         func->state = KLP_DISABLED;
 
         return kobject_init_and_add(&func->kobj, &klp_ktype_func,
-                                    obj->kobj, "%s", func->old_name);
+                                    &obj->kobj, "%s", func->old_name);
 }
 
 /* parts of the initialization that is done only when the object is loaded */
@@ -729,7 +747,7 @@ static int klp_init_object_loaded(struct klp_patch *patch,
                         return ret;
         }
 
-        for (func = obj->funcs; func->old_name; func++) {
+        klp_for_each_func(obj, func) {
                 ret = klp_find_verify_func_addr(obj, func);
                 if (ret)
                         return ret;
@@ -753,11 +771,12 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
         klp_find_object_module(obj);
 
         name = klp_is_module(obj) ? obj->name : "vmlinux";
-        obj->kobj = kobject_create_and_add(name, &patch->kobj);
-        if (!obj->kobj)
-                return -ENOMEM;
+        ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object,
+                                   &patch->kobj, "%s", name);
+        if (ret)
+                return ret;
 
-        for (func = obj->funcs; func->old_name; func++) {
+        klp_for_each_func(obj, func) {
                 ret = klp_init_func(obj, func);
                 if (ret)
                         goto free;
@@ -773,7 +792,7 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
 
 free:
         klp_free_funcs_limited(obj, func);
-        kobject_put(obj->kobj);
+        kobject_put(&obj->kobj);
         return ret;
 }
 
@@ -794,7 +813,7 @@ static int klp_init_patch(struct klp_patch *patch)
         if (ret)
                 goto unlock;
 
-        for (obj = patch->objs; obj->funcs; obj++) {
+        klp_for_each_object(patch, obj) {
                 ret = klp_init_object(patch, obj);
                 if (ret)
                         goto free;
@@ -883,7 +902,7 @@ int klp_register_patch(struct klp_patch *patch)
 }
 EXPORT_SYMBOL_GPL(klp_register_patch);
 
-static void klp_module_notify_coming(struct klp_patch *patch,
+static int klp_module_notify_coming(struct klp_patch *patch,
                                      struct klp_object *obj)
 {
         struct module *pmod = patch->mod;
@@ -891,22 +910,23 @@ static void klp_module_notify_coming(struct klp_patch *patch,
         int ret;
 
         ret = klp_init_object_loaded(patch, obj);
-        if (ret)
-                goto err;
+        if (ret) {
+                pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+                        pmod->name, mod->name, ret);
+                return ret;
+        }
 
         if (patch->state == KLP_DISABLED)
-                return;
+                return 0;
 
         pr_notice("applying patch '%s' to loading module '%s'\n",
                   pmod->name, mod->name);
 
         ret = klp_enable_object(obj);
-        if (!ret)
-                return;
-
-err:
-        pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
-                pmod->name, mod->name, ret);
+        if (ret)
+                pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+                        pmod->name, mod->name, ret);
+        return ret;
 }
 
 static void klp_module_notify_going(struct klp_patch *patch,
@@ -930,6 +950,7 @@ disabled:
 static int klp_module_notify(struct notifier_block *nb, unsigned long action,
                              void *data)
 {
+        int ret;
         struct module *mod = data;
         struct klp_patch *patch;
         struct klp_object *obj;
@@ -949,13 +970,18 @@ static int klp_module_notify(struct notifier_block *nb, unsigned long action,
                 mod->klp_alive = false;
 
         list_for_each_entry(patch, &klp_patches, list) {
-                for (obj = patch->objs; obj->funcs; obj++) {
+                klp_for_each_object(patch, obj) {
                         if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
                                 continue;
 
                         if (action == MODULE_STATE_COMING) {
                                 obj->mod = mod;
-                                klp_module_notify_coming(patch, obj);
+                                ret = klp_module_notify_coming(patch, obj);
+                                if (ret) {
+                                        obj->mod = NULL;
+                                        pr_warn("patch '%s' is in an inconsistent state!\n",
+                                                patch->mod->name);
+                                }
                         } else /* MODULE_STATE_GOING */
                                 klp_module_notify_going(patch, obj);
 
@@ -973,7 +999,7 @@ static struct notifier_block klp_module_nb = {
         .priority = INT_MIN+1, /* called late but before ftrace notifier */
 };
 
-static int klp_init(void)
+static int __init klp_init(void)
 {
         int ret;