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kprobes: Blacklist symbols in arch-defined prohibited area

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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@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2018-12-17 17:20:55 +09:00 committed by Ingo Molnar
parent 76aea1eeb9
commit fb1a59fae8
2 changed files with 56 additions and 14 deletions
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3
include/linux/kprobes.h
View File

@ -242,10 +242,13 @@ extern int arch_init_kprobes(void);
extern void show_registers(struct pt_regs *regs); extern void show_registers(struct pt_regs *regs);
extern void kprobes_inc_nmissed_count(struct kprobe *p); extern void kprobes_inc_nmissed_count(struct kprobe *p);
extern bool arch_within_kprobe_blacklist(unsigned long addr); 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 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 kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
extern bool within_kprobe_blacklist(unsigned long addr); 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 kprobe_insn_cache {
struct mutex mutex; struct mutex mutex;

67
kernel/kprobes.c
View File

@ -2093,6 +2093,47 @@ void dump_kprobe(struct kprobe *kp)
} }
NOKPROBE_SYMBOL(dump_kprobe); 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. * Lookup and populate the kprobe_blacklist.
* *
@ -2104,26 +2145,24 @@ NOKPROBE_SYMBOL(dump_kprobe);
static int __init populate_kprobe_blacklist(unsigned long *start, static int __init populate_kprobe_blacklist(unsigned long *start,
unsigned long *end) unsigned long *end)
{ {
unsigned long entry;
unsigned long *iter; unsigned long *iter;
struct kprobe_blacklist_entry *ent; int ret;
unsigned long entry, offset = 0, size = 0;
for (iter = start; iter < end; iter++) { for (iter = start; iter < end; iter++) {
entry = arch_deref_entry_point((void *)*iter); entry = arch_deref_entry_point((void *)*iter);
ret = kprobe_add_ksym_blacklist(entry);
if (!kernel_text_address(entry) || if (ret == -EINVAL)
!kallsyms_lookup_size_offset(entry, &size, &offset))
continue; continue;
if (ret < 0)
ent = kmalloc(sizeof(*ent), GFP_KERNEL); return ret;
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 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 */ /* Module notifier call back, checking kprobes on the module */