[tip: core/kprobes] kprobes: Support __kprobes blacklist in modules

tip-bot2 for Masami Hiramatsu
2020-05-12T15:19:04Z

The following commit has been merged into the core/kprobes branch of tip:

Commit-ID: 1e6769b0aece51ea7a3dc3117c37d4a5669e4a21
Gitweb: https://git.kernel.org/tip/1e6769b0aece51ea7a3dc3117c37d4a5669e4a21
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Thu, 26 Mar 2020 23:49:48 +09:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 12 May 2020 17:15:32 +02:00

kprobes: Support __kprobes blacklist in modules

Support __kprobes attribute for blacklist functions in modules. The
__kprobes attribute functions are stored in .kprobes.text section.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134059.678201813@linutronix.de

---
include/linux/module.h | 4 ++++-
kernel/kprobes.c | 42 +++++++++++++++++++++++++++++++++++++++++-
kernel/module.c | 4 ++++-
3 files changed, 50 insertions(+)

diff --git a/include/linux/module.h b/include/linux/module.h
index 1ad393e..369c354 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -489,6 +489,10 @@ struct module {
unsigned int num_ftrace_callsites;
unsigned long *ftrace_callsites;
#endif
+#ifdef CONFIG_KPROBES
+ void *kprobes_text_start;
+ unsigned int kprobes_text_size;
+#endif

#ifdef CONFIG_LIVEPATCH
bool klp; /* Is this a livepatch module? */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 570d608..b754999 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2179,6 +2179,19 @@ 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);
+ }
+}
+
int __init __weak arch_populate_kprobe_blacklist(void)
{
return 0;
@@ -2215,6 +2228,28 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
return ret ? : arch_populate_kprobe_blacklist();
}

+static void add_module_kprobe_blacklist(struct module *mod)
+{
+ unsigned long start, end;
+
+ start = (unsigned long)mod->kprobes_text_start;
+ if (start) {
+ end = start + mod->kprobes_text_size;
+ kprobe_add_area_blacklist(start, end);
+ }
+}
+
+static void remove_module_kprobe_blacklist(struct module *mod)
+{
+ unsigned long start, end;
+
+ start = (unsigned long)mod->kprobes_text_start;
+ if (start) {
+ end = start + mod->kprobes_text_size;
+ kprobe_remove_area_blacklist(start, end);
+ }
+}
+
/* Module notifier call back, checking kprobes on the module */
static int kprobes_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
@@ -2225,6 +2260,11 @@ static int kprobes_module_callback(struct notifier_block *nb,
unsigned int i;
int checkcore = (val == MODULE_STATE_GOING);

+ if (val == MODULE_STATE_COMING) {
+ mutex_lock(&kprobe_mutex);
+ add_module_kprobe_blacklist(mod);
+ mutex_unlock(&kprobe_mutex);
+ }
if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
return NOTIFY_DONE;

@@ -2255,6 +2295,8 @@ static int kprobes_module_callback(struct notifier_block *nb,
kill_kprobe(p);
}
}
+ if (val == MODULE_STATE_GOING)
+ remove_module_kprobe_blacklist(mod);
mutex_unlock(&kprobe_mutex);
return NOTIFY_DONE;
}
diff --git a/kernel/module.c b/kernel/module.c
index 646f1e2..978f3fa 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3194,6 +3194,10 @@ static int find_module_sections(struct module *mod, struct load_info *info)
sizeof(*mod->ei_funcs),
&mod->num_ei_funcs);
#endif
+#ifdef CONFIG_KPROBES
+ mod->kprobes_text_start = section_objs(info, ".kprobes.text", 1,
+ &mod->kprobes_text_size);
+#endif
mod->extable = section_objs(info, "__ex_table",
sizeof(*mod->extable), &mod->num_exentries);