From 7582b7be16d0ba90e3dbd9575a730cabd9eb852a Mon Sep 17 00:00:00 2001 From: "Mike Rapoport (IBM)" Date: Sun, 5 May 2024 19:06:27 +0300 Subject: [PATCH] kprobes: remove dependency on CONFIG_MODULES kprobes depended on CONFIG_MODULES because it has to allocate memory for code. Since code allocations are now implemented with execmem, kprobes can be enabled in non-modular kernels. Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the dependency of CONFIG_KPROBES on CONFIG_MODULES. Signed-off-by: Mike Rapoport (IBM) Acked-by: Masami Hiramatsu (Google) [mcgrof: rebase in light of NEED_TASKS_RCU ] Signed-off-by: Luis Chamberlain --- arch/Kconfig | 2 +- include/linux/module.h | 9 ++++++ kernel/kprobes.c | 55 +++++++++++++++++++++++-------------- kernel/trace/trace_kprobe.c | 20 +++++++++++++- 4 files changed, 63 insertions(+), 23 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index ee1ccbde50ef..b34946d90e4b 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -60,9 +60,9 @@ config GENERIC_ENTRY config KPROBES bool "Kprobes" - depends on MODULES depends on HAVE_KPROBES select KALLSYMS + select EXECMEM select NEED_TASKS_RCU help Kprobes allows you to trap at almost any kernel address and diff --git a/include/linux/module.h b/include/linux/module.h index 1153b0d99a80..ffa1c603163c 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -605,6 +605,11 @@ static inline bool module_is_live(struct module *mod) return mod->state != MODULE_STATE_GOING; } +static inline bool module_is_coming(struct module *mod) +{ + return mod->state == MODULE_STATE_COMING; +} + struct module *__module_text_address(unsigned long addr); struct module *__module_address(unsigned long addr); bool is_module_address(unsigned long addr); @@ -857,6 +862,10 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr) return ptr; } +static inline bool module_is_coming(struct module *mod) +{ + return false; +} #endif /* CONFIG_MODULES */ #ifdef CONFIG_SYSFS diff --git a/kernel/kprobes.c b/kernel/kprobes.c index ddd7cdc16edf..ca2c6cbd42d2 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1588,7 +1588,7 @@ static int check_kprobe_address_safe(struct kprobe *p, } /* Get module refcount and reject __init functions for loaded modules. */ - if (*probed_mod) { + if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) { /* * We must hold a refcount of the probed module while updating * its code to prohibit unexpected unloading. @@ -1603,12 +1603,13 @@ static int check_kprobe_address_safe(struct kprobe *p, * kprobes in there. */ if (within_module_init((unsigned long)p->addr, *probed_mod) && - (*probed_mod)->state != MODULE_STATE_COMING) { + !module_is_coming(*probed_mod)) { module_put(*probed_mod); *probed_mod = NULL; ret = -ENOENT; } } + out: preempt_enable(); jump_label_unlock(); @@ -2488,24 +2489,6 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) return 0; } -/* Remove all symbols in given area from kprobe blacklist */ -static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) -{ - struct kprobe_blacklist_entry *ent, *n; - - list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { - if (ent->start_addr < start || ent->start_addr >= end) - continue; - list_del(&ent->list); - kfree(ent); - } -} - -static void kprobe_remove_ksym_blacklist(unsigned long entry) -{ - kprobe_remove_area_blacklist(entry, entry + 1); -} - int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, char *type, char *sym) { @@ -2570,6 +2553,25 @@ static int __init populate_kprobe_blacklist(unsigned long *start, return ret ? : arch_populate_kprobe_blacklist(); } +#ifdef CONFIG_MODULES +/* Remove all symbols in given area from kprobe blacklist */ +static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) +{ + struct kprobe_blacklist_entry *ent, *n; + + list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { + if (ent->start_addr < start || ent->start_addr >= end) + continue; + list_del(&ent->list); + kfree(ent); + } +} + +static void kprobe_remove_ksym_blacklist(unsigned long entry) +{ + kprobe_remove_area_blacklist(entry, entry + 1); +} + static void add_module_kprobe_blacklist(struct module *mod) { unsigned long start, end; @@ -2672,6 +2674,17 @@ static struct notifier_block kprobe_module_nb = { .priority = 0 }; +static int kprobe_register_module_notifier(void) +{ + return register_module_notifier(&kprobe_module_nb); +} +#else +static int kprobe_register_module_notifier(void) +{ + return 0; +} +#endif /* CONFIG_MODULES */ + void kprobe_free_init_mem(void) { void *start = (void *)(&__init_begin); @@ -2731,7 +2744,7 @@ static int __init init_kprobes(void) if (!err) err = register_die_notifier(&kprobe_exceptions_nb); if (!err) - err = register_module_notifier(&kprobe_module_nb); + err = kprobe_register_module_notifier(); kprobes_initialized = (err == 0); kprobe_sysctls_init(); diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 14099cc17fc9..2cb2a3951b4f 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -111,6 +111,7 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk, return strncmp(module_name(mod), name, len) == 0 && name[len] == ':'; } +#ifdef CONFIG_MODULES static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) { char *p; @@ -129,6 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) return ret; } +#else +static inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) +{ + return false; +} +#endif static bool trace_kprobe_is_busy(struct dyn_event *ev) { @@ -670,6 +677,7 @@ end: return ret; } +#ifdef CONFIG_MODULES /* Module notifier call back, checking event on the module */ static int trace_kprobe_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -704,6 +712,16 @@ static struct notifier_block trace_kprobe_module_nb = { .notifier_call = trace_kprobe_module_callback, .priority = 1 /* Invoked after kprobe module callback */ }; +static int trace_kprobe_register_module_notifier(void) +{ + return register_module_notifier(&trace_kprobe_module_nb); +} +#else +static int trace_kprobe_register_module_notifier(void) +{ + return 0; +} +#endif /* CONFIG_MODULES */ static int count_symbols(void *data, unsigned long unused) { @@ -1933,7 +1951,7 @@ static __init int init_kprobe_trace_early(void) if (ret) return ret; - if (register_module_notifier(&trace_kprobe_module_nb)) + if (trace_kprobe_register_module_notifier()) return -EINVAL; return 0;