From 376e242429bf8539ef39a080ac113c8799840b13 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 17 Apr 2014 17:17:05 +0900 Subject: kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Introduce NOKPROBE_SYMBOL() macro which builds a kprobes blacklist at kernel build time. The usage of this macro is similar to EXPORT_SYMBOL(), placed after the function definition: NOKPROBE_SYMBOL(function); Since this macro will inhibit inlining of static/inline functions, this patch also introduces a nokprobe_inline macro for static/inline functions. In this case, we must use NOKPROBE_SYMBOL() for the inline function caller. When CONFIG_KPROBES=y, the macro stores the given function address in the "_kprobe_blacklist" section. Since the data structures are not fully initialized by the macro (because there is no "size" information), those are re-initialized at boot time by using kallsyms. Signed-off-by: Masami Hiramatsu Link: http://lkml.kernel.org/r/20140417081705.26341.96719.stgit@ltc230.yrl.intra.hitachi.co.jp Cc: Alok Kataria Cc: Ananth N Mavinakayanahalli Cc: Andrew Morton Cc: Anil S Keshavamurthy Cc: Arnd Bergmann Cc: Christopher Li Cc: Chris Wright Cc: David S. Miller Cc: Jan-Simon Möller Cc: Jeremy Fitzhardinge Cc: Linus Torvalds Cc: Randy Dunlap Cc: Rusty Russell Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-sparse@vger.kernel.org Cc: virtualization@lists.linux-foundation.org Signed-off-by: Ingo Molnar --- kernel/kprobes.c | 100 +++++++++++++++++++++++++++------------------------- kernel/sched/core.c | 1 + 2 files changed, 53 insertions(+), 48 deletions(-) (limited to 'kernel') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 5b5ac76..5ffc687 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -86,18 +86,8 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) return &(kretprobe_table_locks[hash].lock); } -/* - * Normally, functions that we'd want to prohibit kprobes in, are marked - * __kprobes. But, there are cases where such functions already belong to - * a different section (__sched for preempt_schedule) - * - * For such cases, we now have a blacklist - */ -static struct kprobe_blackpoint kprobe_blacklist[] = { - {"preempt_schedule",}, - {"native_get_debugreg",}, - {NULL} /* Terminator */ -}; +/* Blacklist -- list of struct kprobe_blacklist_entry */ +static LIST_HEAD(kprobe_blacklist); #ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* @@ -1328,24 +1318,22 @@ bool __weak arch_within_kprobe_blacklist(unsigned long addr) addr < (unsigned long)__kprobes_text_end; } -static int __kprobes in_kprobes_functions(unsigned long addr) +static bool __kprobes within_kprobe_blacklist(unsigned long addr) { - struct kprobe_blackpoint *kb; + struct kprobe_blacklist_entry *ent; if (arch_within_kprobe_blacklist(addr)) - return -EINVAL; + return true; /* * If there exists a kprobe_blacklist, verify and * fail any probe registration in the prohibited area */ - for (kb = kprobe_blacklist; kb->name != NULL; kb++) { - if (kb->start_addr) { - if (addr >= kb->start_addr && - addr < (kb->start_addr + kb->range)) - return -EINVAL; - } + list_for_each_entry(ent, &kprobe_blacklist, list) { + if (addr >= ent->start_addr && addr < ent->end_addr) + return true; } - return 0; + + return false; } /* @@ -1436,7 +1424,7 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p, /* Ensure it is not in reserved area nor out of text */ if (!kernel_text_address((unsigned long) p->addr) || - in_kprobes_functions((unsigned long) p->addr) || + within_kprobe_blacklist((unsigned long) p->addr) || jump_label_text_reserved(p->addr, p->addr)) { ret = -EINVAL; goto out; @@ -2022,6 +2010,38 @@ void __kprobes dump_kprobe(struct kprobe *kp) kp->symbol_name, kp->addr, kp->offset); } +/* + * Lookup and populate the kprobe_blacklist. + * + * Unlike the kretprobe blacklist, we'll need to determine + * the range of addresses that belong to the said functions, + * since a kprobe need not necessarily be at the beginning + * of a function. + */ +static int __init populate_kprobe_blacklist(unsigned long *start, + unsigned long *end) +{ + unsigned long *iter; + struct kprobe_blacklist_entry *ent; + unsigned long offset = 0, size = 0; + + for (iter = start; iter < end; iter++) { + if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) { + pr_err("Failed to find blacklist %p\n", (void *)*iter); + continue; + } + + ent = kmalloc(sizeof(*ent), GFP_KERNEL); + if (!ent) + return -ENOMEM; + ent->start_addr = *iter; + ent->end_addr = *iter + size; + INIT_LIST_HEAD(&ent->list); + list_add_tail(&ent->list, &kprobe_blacklist); + } + return 0; +} + /* Module notifier call back, checking kprobes on the module */ static int __kprobes kprobes_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -2065,14 +2085,13 @@ static struct notifier_block kprobe_module_nb = { .priority = 0 }; +/* Markers of _kprobe_blacklist section */ +extern unsigned long __start_kprobe_blacklist[]; +extern unsigned long __stop_kprobe_blacklist[]; + static int __init init_kprobes(void) { int i, err = 0; - unsigned long offset = 0, size = 0; - char *modname, namebuf[KSYM_NAME_LEN]; - const char *symbol_name; - void *addr; - struct kprobe_blackpoint *kb; /* FIXME allocate the probe table, currently defined statically */ /* initialize all list heads */ @@ -2082,26 +2101,11 @@ static int __init init_kprobes(void) raw_spin_lock_init(&(kretprobe_table_locks[i].lock)); } - /* - * Lookup and populate the kprobe_blacklist. - * - * Unlike the kretprobe blacklist, we'll need to determine - * the range of addresses that belong to the said functions, - * since a kprobe need not necessarily be at the beginning - * of a function. - */ - for (kb = kprobe_blacklist; kb->name != NULL; kb++) { - kprobe_lookup_name(kb->name, addr); - if (!addr) - continue; - - kb->start_addr = (unsigned long)addr; - symbol_name = kallsyms_lookup(kb->start_addr, - &size, &offset, &modname, namebuf); - if (!symbol_name) - kb->range = 0; - else - kb->range = size; + err = populate_kprobe_blacklist(__start_kprobe_blacklist, + __stop_kprobe_blacklist); + if (err) { + pr_err("kprobes: failed to populate blacklist: %d\n", err); + pr_err("Please take care of using kprobes.\n"); } if (kretprobe_blacklist_size) { diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 268a45e..6863631 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2804,6 +2804,7 @@ asmlinkage void __sched notrace preempt_schedule(void) barrier(); } while (need_resched()); } +NOKPROBE_SYMBOL(preempt_schedule); EXPORT_SYMBOL(preempt_schedule); #endif /* CONFIG_PREEMPT */ -- cgit v1.1