From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit fb1a59fae8baa3f3c69b72a87ff94fc4fa5683ec ]
Blacklist symbols in arch-defined probe-prohibited areas. With this change, user can see all symbols which are prohibited to probe in debugfs.
All archtectures which have custom prohibit areas should define its own arch_populate_kprobe_blacklist() function, but unless that, all symbols marked __kprobes are blacklisted.
Reported-by: Andrea Righi righi.andrea@gmail.com Tested-by: Andrea Righi righi.andrea@gmail.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: Andy Lutomirski luto@kernel.org Cc: Anil S Keshavamurthy anil.s.keshavamurthy@intel.com Cc: Borislav Petkov bp@alien8.de Cc: David S. Miller davem@davemloft.net Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Yonghong Song yhs@fb.com Link: http://lkml.kernel.org/r/154503485491.26176.15823229545155174796.stgit@devbo... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/kprobes.h | 3 ++ kernel/kprobes.c | 67 ++++++++++++++++++++++++++++++++--------- 2 files changed, 56 insertions(+), 14 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 32cae0f35b9d4..9adb92ad24d3f 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -243,10 +243,13 @@ extern int arch_init_kprobes(void); extern void show_registers(struct pt_regs *regs); extern void kprobes_inc_nmissed_count(struct kprobe *p); extern bool arch_within_kprobe_blacklist(unsigned long addr); +extern int arch_populate_kprobe_blacklist(void); extern bool arch_kprobe_on_func_entry(unsigned long offset); extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
extern bool within_kprobe_blacklist(unsigned long addr); +extern int kprobe_add_ksym_blacklist(unsigned long entry); +extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
struct kprobe_insn_cache { struct mutex mutex; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index b8efca9dc2cbb..c4f1acb2e7d20 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2090,6 +2090,47 @@ void dump_kprobe(struct kprobe *kp) } NOKPROBE_SYMBOL(dump_kprobe);
+int kprobe_add_ksym_blacklist(unsigned long entry) +{ + struct kprobe_blacklist_entry *ent; + unsigned long offset = 0, size = 0; + + if (!kernel_text_address(entry) || + !kallsyms_lookup_size_offset(entry, &size, &offset)) + return -EINVAL; + + ent = kmalloc(sizeof(*ent), GFP_KERNEL); + if (!ent) + return -ENOMEM; + ent->start_addr = entry; + ent->end_addr = entry + size; + INIT_LIST_HEAD(&ent->list); + list_add_tail(&ent->list, &kprobe_blacklist); + + return (int)size; +} + +/* Add all symbols in given area into kprobe blacklist */ +int kprobe_add_area_blacklist(unsigned long start, unsigned long end) +{ + unsigned long entry; + int ret = 0; + + for (entry = start; entry < end; entry += ret) { + ret = kprobe_add_ksym_blacklist(entry); + if (ret < 0) + return ret; + if (ret == 0) /* In case of alias symbol */ + ret = 1; + } + return 0; +} + +int __init __weak arch_populate_kprobe_blacklist(void) +{ + return 0; +} + /* * Lookup and populate the kprobe_blacklist. * @@ -2101,26 +2142,24 @@ NOKPROBE_SYMBOL(dump_kprobe); static int __init populate_kprobe_blacklist(unsigned long *start, unsigned long *end) { + unsigned long entry; unsigned long *iter; - struct kprobe_blacklist_entry *ent; - unsigned long entry, offset = 0, size = 0; + int ret;
for (iter = start; iter < end; iter++) { entry = arch_deref_entry_point((void *)*iter); - - if (!kernel_text_address(entry) || - !kallsyms_lookup_size_offset(entry, &size, &offset)) + ret = kprobe_add_ksym_blacklist(entry); + if (ret == -EINVAL) continue; - - ent = kmalloc(sizeof(*ent), GFP_KERNEL); - if (!ent) - return -ENOMEM; - ent->start_addr = entry; - ent->end_addr = entry + size; - INIT_LIST_HEAD(&ent->list); - list_add_tail(&ent->list, &kprobe_blacklist); + if (ret < 0) + return ret; } - return 0; + + /* Symbols in __kprobes_text are blacklisted */ + ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, + (unsigned long)__kprobes_text_end); + + return ret ? : arch_populate_kprobe_blacklist(); }
/* Module notifier call back, checking kprobes on the module */