To blacklist the functions in a module (e.g. user-defined
kprobe handler and the functions invoked from it), expand
blacklist support for modules.
With this change, users can use NOKPROBE_SYMBOL() macro in
their own modules.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
Documentation/kprobes.txt | 8 ++++++++
include/linux/module.h | 5 +++++
kernel/kprobes.c | 44 +++++++++++++++++++++++++++++++++++++++++---
kernel/module.c | 6 ++++++
4 files changed, 60 insertions(+), 3 deletions(-)
diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 7062631..c6634b3 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -512,6 +512,14 @@ int enable_jprobe(struct jprobe *jp);
Enables *probe which has been disabled by disable_*probe(). You must specify
the probe which has been registered.
+4.9 NOKPROBE_SYMBOL()
+
+#include <linux/kprobes.h>
+NOKPROBE_SYMBOL(FUNCTION);
+
+Protects given FUNCTION from other kprobes. This is useful for handler
+functions and functions called from the handlers.
+
5. Kprobes Features and Limitations
Kprobes allows multiple probes at the same address. Currently,
diff --git a/include/linux/module.h b/include/linux/module.h
index 05f2447..acb682b 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -16,6 +16,7 @@
#include <linux/kobject.h>
#include <linux/moduleparam.h>
#include <linux/tracepoint.h>
+#include <linux/kprobes.h>
#include <linux/export.h>
#include <linux/percpu.h>
@@ -360,6 +361,10 @@ struct module
unsigned int num_ftrace_callsites;
unsigned long *ftrace_callsites;
#endif
+#ifdef CONFIG_KPROBES
+ struct kprobe_blackpoint **kprobe_blacklist;
+ unsigned int num_kprobe_blacklist;
+#endif
#ifdef CONFIG_MODULE_UNLOAD
/* What modules depend on me? */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 007235e..4e8ce87 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -88,6 +88,7 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
/* Blacklist -- list of struct kprobe_blackpoint */
static LIST_HEAD(kprobe_blacklist);
+static DEFINE_MUTEX(kprobe_blacklist_mutex);
#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
/*
@@ -1416,6 +1417,7 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
#endif
}
+ mutex_lock(&kprobe_blacklist_mutex);
jump_label_lock();
preempt_disable();
@@ -1453,6 +1455,7 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
out:
preempt_enable();
jump_label_unlock();
+ mutex_unlock(&kprobe_blacklist_mutex);
return ret;
}
@@ -2007,6 +2010,11 @@ void __kprobes dump_kprobe(struct kprobe *kp)
kp->symbol_name, kp->addr, kp->offset);
}
+static void populate_kprobe_blacklist(struct kprobe_blackpoint **start,
+ struct kprobe_blackpoint **end);
+static void shrink_kprobe_blacklist(struct kprobe_blackpoint **start,
+ struct kprobe_blackpoint **end);
+
/* Module notifier call back, checking kprobes on the module */
static int __kprobes kprobes_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
@@ -2017,6 +2025,16 @@ static int __kprobes kprobes_module_callback(struct notifier_block *nb,
unsigned int i;
int checkcore = (val == MODULE_STATE_GOING);
+ /* Add/remove module blacklist */
+ if (val == MODULE_STATE_COMING)
+ populate_kprobe_blacklist(mod->kprobe_blacklist,
+ mod->kprobe_blacklist +
+ mod->num_kprobe_blacklist);
+ else if (val == MODULE_STATE_GOING)
+ shrink_kprobe_blacklist(mod->kprobe_blacklist,
+ mod->kprobe_blacklist +
+ mod->num_kprobe_blacklist);
+
if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
return NOTIFY_DONE;
@@ -2050,6 +2068,18 @@ static struct notifier_block kprobe_module_nb = {
.priority = 0
};
+/* Shrink the blacklist */
+static void shrink_kprobe_blacklist(struct kprobe_blackpoint **start,
+ struct kprobe_blackpoint **end)
+{
+ struct kprobe_blackpoint **iter;
+
+ mutex_lock(&kprobe_blacklist_mutex);
+ for (iter = start; (unsigned long)iter < (unsigned long)end; iter++)
+ list_del(&(*iter)->list);
+ mutex_unlock(&kprobe_blacklist_mutex);
+}
+
/*
* Lookup and populate the kprobe_blacklist.
*
@@ -2058,14 +2088,15 @@ static struct notifier_block kprobe_module_nb = {
* since a kprobe need not necessarily be at the beginning
* of a function.
*/
-static void __init populate_kprobe_blacklist(struct kprobe_blackpoint **start,
- struct kprobe_blackpoint **end)
+static void populate_kprobe_blacklist(struct kprobe_blackpoint **start,
+ struct kprobe_blackpoint **end)
{
struct kprobe_blackpoint **iter, *bp;
unsigned long offset = 0, size = 0;
char *modname, namebuf[128];
const char *symbol_name;
+ mutex_lock(&kprobe_blacklist_mutex);
for (iter = start; (unsigned long)iter < (unsigned long)end; iter++) {
bp = *iter;
symbol_name = kallsyms_lookup(bp->start_addr,
@@ -2077,6 +2108,7 @@ static void __init populate_kprobe_blacklist(struct kprobe_blackpoint **start,
INIT_LIST_HEAD(&bp->list);
list_add_tail(&bp->list, &kprobe_blacklist);
}
+ mutex_unlock(&kprobe_blacklist_mutex);
}
extern struct kprobe_blackpoint *__start_kprobe_blacklist[];
@@ -2227,6 +2259,7 @@ static const struct file_operations debugfs_kprobes_operations = {
/* kprobes/blacklist -- shows which functions can not be probed */
static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
{
+ mutex_lock(&kprobe_blacklist_mutex);
return seq_list_start(&kprobe_blacklist, *pos);
}
@@ -2235,6 +2268,11 @@ static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
return seq_list_next(v, &kprobe_blacklist, pos);
}
+static void *kprobe_blacklist_seq_stop(struct seq_file *m, loff_t *pos)
+{
+ mutex_unlock(&kprobe_blacklist_mutex);
+}
+
static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
{
struct kprobe_blackpoint *bp =
@@ -2248,7 +2286,7 @@ static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
static const struct seq_operations kprobe_blacklist_seq_ops = {
.start = kprobe_blacklist_seq_start,
.next = kprobe_blacklist_seq_next,
- .stop = kprobe_seq_stop, /* Reuse void function */
+ .stop = kprobe_blacklist_seq_stop,
.show = kprobe_blacklist_seq_show,
};
diff --git a/kernel/module.c b/kernel/module.c
index dc58274..4cc844c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -58,6 +58,7 @@
#include <linux/percpu.h>
#include <linux/kmemleak.h>
#include <linux/jump_label.h>
+#include <linux/kprobes.h>
#include <linux/pfn.h>
#include <linux/bsearch.h>
#include <linux/fips.h>
@@ -2796,6 +2797,11 @@ static void find_module_sections(struct module *mod, struct load_info *info)
sizeof(*mod->ftrace_callsites),
&mod->num_ftrace_callsites);
#endif
+#ifdef CONFIG_KPROBES
+ mod->kprobe_blacklist = section_objs(info, "_kprobe_blacklist",
+ sizeof(*mod->kprobe_blacklist),
+ &mod->num_kprobe_blacklist);
+#endif
mod->extable = section_objs(info, "__ex_table",
sizeof(*mod->extable), &mod->num_exentries);
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