diff options
| -rw-r--r-- | include/linux/kprobes.h | 3 | ||||
| -rw-r--r-- | kernel/kprobes.c | 42 |
2 files changed, 35 insertions, 10 deletions
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 10005bc92a31..669756bc20a2 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -68,6 +68,9 @@ struct kprobe { /* list of kprobes for multi-handler support */ struct list_head list; + /* Indicates that the corresponding module has been ref counted */ + unsigned int mod_refcounted; + /*count the number of times this probe was temporarily disarmed */ unsigned long nmissed; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 34a885bb82e0..3ea6325228da 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -449,19 +449,32 @@ static int __kprobes in_kprobes_functions(unsigned long addr) return 0; } -int __kprobes register_kprobe(struct kprobe *p) +static int __kprobes __register_kprobe(struct kprobe *p, + unsigned long called_from) { int ret = 0; struct kprobe *old_p; - struct module *mod; + struct module *probed_mod; if ((!kernel_text_address((unsigned long) p->addr)) || in_kprobes_functions((unsigned long) p->addr)) return -EINVAL; - if ((mod = module_text_address((unsigned long) p->addr)) && - (unlikely(!try_module_get(mod)))) - return -EINVAL; + p->mod_refcounted = 0; + /* Check are we probing a module */ + if ((probed_mod = module_text_address((unsigned long) p->addr))) { + struct module *calling_mod = module_text_address(called_from); + /* We must allow modules to probe themself and + * in this case avoid incrementing the module refcount, + * so as to allow unloading of self probing modules. + */ + if (calling_mod && (calling_mod != probed_mod)) { + if (unlikely(!try_module_get(probed_mod))) + return -EINVAL; + p->mod_refcounted = 1; + } else + probed_mod = NULL; + } p->nmissed = 0; down(&kprobe_mutex); @@ -483,11 +496,17 @@ int __kprobes register_kprobe(struct kprobe *p) out: up(&kprobe_mutex); - if (ret && mod) - module_put(mod); + if (ret && probed_mod) + module_put(probed_mod); return ret; } +int __kprobes register_kprobe(struct kprobe *p) +{ + return __register_kprobe(p, + (unsigned long)__builtin_return_address(0)); +} + void __kprobes unregister_kprobe(struct kprobe *p) { struct module *mod; @@ -524,7 +543,8 @@ valid_p: up(&kprobe_mutex); synchronize_sched(); - if ((mod = module_text_address((unsigned long)p->addr))) + if (p->mod_refcounted && + (mod = module_text_address((unsigned long)p->addr))) module_put(mod); if (cleanup_p) { @@ -547,7 +567,8 @@ int __kprobes register_jprobe(struct jprobe *jp) jp->kp.pre_handler = setjmp_pre_handler; jp->kp.break_handler = longjmp_break_handler; - return register_kprobe(&jp->kp); + return __register_kprobe(&jp->kp, + (unsigned long)__builtin_return_address(0)); } void __kprobes unregister_jprobe(struct jprobe *jp) @@ -587,7 +608,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp) rp->nmissed = 0; /* Establish function entry probe point */ - if ((ret = register_kprobe(&rp->kp)) != 0) + if ((ret = __register_kprobe(&rp->kp, + (unsigned long)__builtin_return_address(0))) != 0) free_rp_inst(rp); return ret; } |